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STORMWATER MANAGEMENT PLAN
THE LANDING AT LEMAY
FORT COLLINS, CO
November 1, 2023
AVANT CIVIL GROUP, LLC
FORT COLLINS, CO 80524
(970)286-7995
_____________________________________________________________________________________________________________________________
AVANT CIVIL GROUP, LLC SWMP: THE LANDING AT LEMAY
1337 RIVERSIDE AVE. #2, FORT COLLINS, CO 80524
November 1, 2023
City of Fort Collins
Stormwater Development Review
700 Wood Street
Fort Collins, CO 80521
RE: STORMWATER MANAGEMENT PLAN
THE LANDING AT LEMAY
To Whom It May Concern:
Avant Civil Group (Avant) is pleased to submit this Stormwater Management Plan for The Landing at
Lemay project. This report outlines Best Management Practices (BMPs) to be implemented with the
proposed construction to minimize potential pollutants in stormwater discharges.
We have prepared this report to accompany the Colorado Department of Public Health and Environment
General Permit for Stormwater Discharge Associated with Construction Activities (aka, Stormwater
Discharge Permit or SDP). The General Permit No. for this SDP is (to be filled-in by permittee), and the
Certification No. for this SDP is (to be filled-in by permittee). The Permit Certification is effective beginning
(to be filled-in by permittee), and initial certification expires (to be filled-in by permittee). A copy of the
issuance cover letter can be found in Appendix D of this document (to be filled-in by permittee).
Please note this Stormwater Management plan (including the Site Maps) is not a static document. It is a
dynamic device that should be kept current and logged as construction occurs. As such, this version was
prepared to facilitate initial plan approvals and permits but does not necessarily reflect the final version or
the transitions throughout the construction process. As the site develops and changes, the contractor is
expected and encouraged to change the content, so the SWMP works as effectively and efficiently as
possible. It shall be the responsibility of the SWMP Administrator and/or the permit holder (or applicant
thereof) to ensure the plan is properly maintained and followed.
If you should have any questions or comments as you review this report, please feel free to contact us at
your convenience.
Sincerely,
AVANT CIVIL GROUP, LLC
DANNY WEBER, PE
Principal
TABLE OF CONTENTS`
_____________________________________________________________________________________________________________________________
AVANT CIVIL GROUP, LLC SWMP: THE LANDING AT LEMAY
1337 RIVERSIDE AVE. #2, FORT COLLINS, CO 80524
1.0 CONTENTS
2.0 PROJECT DESCRIPTIONS AND NATURE OF CONSTRUCTION ......................................... 1
2.1 EXISTING SITE DESCRIPTION .................................................................................................................................. 1
2.2 NATURE OF CONSTRUCTION ACTIVITY ............................................................................................................. 1
2.3 SITE DISTURBANCE ..................................................................................................................................................... 2
2.4 EXISTING TOPOGRAPHIC AND SOIL DATA ...................................................................................................... 2
2.5 RECEIVING WATERS ................................................................................................................................................... 2
2.6 EXISTING SITE CONDITIONS AND VEGETATION ............................................................................................ 3
2.7 EXISTING GROUNDWATER ...................................................................................................................................... 3
2.8 EXISTING GROUND CONTAMINATION .............................................................................................................. 3
3.0 PROPOSED CONSTRUCTION ACTIVITIES ........................................................................... 3
3.1 SEQUENCE OF MAJOR ACTIVITIES ....................................................................................................................... 3
4.0 GENERAL REQUIREMENTS .................................................................................................. 4
4.1 OBJECTIVES .................................................................................................................................................................... 4
4.2 SMWP AVAILABILITY .................................................................................................................................................. 4
4.3 DEFINITIONS ................................................................................................................................................................. 4
4.4 ADDITIONAL PERMITTING ....................................................................................................................................... 4
5.0 ENVIRONMENTAL IMPACT ................................................................................................. 5
6.0 POTENTIAL POLLUTION SOURCES ..................................................................................... 5
6.1 DISTURBED AND STORED SOILS........................................................................................................................... 5
6.2 VEHICLE TRACKING OF SEDIMENT ...................................................................................................................... 6
6.3 MANAGEMENT OF CONTAMINATED SOILS .................................................................................................... 6
6.4 LOADING AND UNLOADING OPERATIONS ..................................................................................................... 6
6.5 OUTDOOR STORAGE OF CONSTRUCTION SITE MATERIALS, BUILDING MATERIALS,
CHEMICALS, ETC. ......................................................................................................................................................... 7
6.6 BULK STORAGE OF MATERIALS ............................................................................................................................. 7
6.7 VEHICLE AND EQUIPMENT MAINTENANCE AND FUELING....................................................................... 7
6.8 SIGNIFICANT DUST OR PARTICULATE GENERATING PROCESSES .......................................................... 7
6.9 ROUTING MAINTENANCE ACTIVITIES INVOLVING FERTILIZER, PESTICIDES, DETERGENTS,
FUELS, SOLVENTS, OILS ............................................................................................................................................ 8
6.10 ON-SITE WASTE MANAGEMENT PRACTICES................................................................................................... 8
6.11 CONCRETE TRUCK/EQUIPMENT WASHING ..................................................................................................... 9
6.12 DEDICATED ASPHALT AND CONCRETE BATCH PLANTS ............................................................................ 9
6.13 NON-INDUSTRIAL WASTE SOURCES SUCH AS WORKER TRASH AND PORTABLE TOILETS ........ 9
6.14 SAW CUTTING AND GRINDING ......................................................................................................................... 10
6.15 MATERIAL HANDLING AND SPILL PREVENTION ......................................................................................... 10
6.16 NON-STORMWATER DISCHARGES, INCLUDING CONSTRUCTION DEWATERING NOT
COVERED UNDER THE CONSTRUCTION DEWATERING DISCHARGES GENERAL PERMIT AND
WASH WATER THAT MAY CONTRIBUTE TO POLLUTANTS TO THE MS4 .......................................... 11
7.0 STORMWATER MANAGEMENT CONTROLS ............... ERROR! BOOKMARK NOT DEFINED.
7.1 SWMP ADMINISTRATOR ....................................................................................................................................... 11
7.2 OWNER INFORMATION ................................................................. ERROR! BOOKMARK NOT DEFINED.
7.3 BEST MANAGEMENT PRACTICES (BMPS) FOR STORMWATER POLLUTION PREVENTION ........ 12
TABLE OF CONTENTS`
_____________________________________________________________________________________________________________________________
AVANT CIVIL GROUP, LLC SWMP: THE LANDING AT LEMAY
1337 RIVERSIDE AVE. #2, FORT COLLINS, CO 80524
7.4 STRUCTURAL PRACTICES FOR EROSION AND SEDIMENT CONTROL ................................................ 13
7.5 NON-STRUCTURAL PRACTICES FOR EROSION AND SEDIMENT CONTROL .................................... 16
7.6 PHASED BMP INSTALLATION .............................................................................................................................. 18
7.7 BMP INSPECTION ..................................................................................................................................................... 19
7.8 BMP MAINTENANCE ............................................................................................................................................... 20
7.9 RECORD KEEPING ..................................................................................................................................................... 20
8.0 FINAL STABILIZATION AND LONG-TERM STORMWATER MANAGEMENT ................. 21
8.1 FINAL STABILIZATION ............................................................................................................................................ 21
8.2 LONG-TERM STORMWATER MANAGEMENT ............................................................................................... 22
9.0 ADDITIONAL SWMP AND BMP RESOURCES ................................................................... 24
10.0 REFERENCES ........................................................................................................................ 24
APPENDIX C – LANDSCAPE PLAN
APPENDIX D – COPIES OF PERMITS/APPLICATIONS
APPENDIX E – INSPECTION LOGS
APPENDIX F – CONTRACTOR INSERTS (AS NEEDED)
APPENDIX G – CONTRACTOR INSERTS (AS NEEDED)
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2.0 PROJECT DESCRIPTIONS AND NATURE OF CONSTRUCTION
2.1 EXISTING SITE DESCRIPTION
A tract of land located in the northwest quarter of Section 7, Township 7 North, Range 68 West of
the 6th P.M., City of Fort Collins, County of Larimer, State of Colorado. More specifically it is 28.187-
acres, roughly 19.3 of which is being developed, southeast of the Lemay Ave overpass of Vine Dr.
2.2 NATURE OF CONSTRUCTION ACTIVITY
The project includes construction of a portion of a 2-lane arterial road that will run along the
eastern property line. There are two access points into the development, one being north bound
off existing Duff Drive, and the second being east bound at the constructed intersection of Link
Lane and Cordova Road. The development will include 9 large multifamily buildings and 8 Carraige
Houses, along with a maintenance shed, a private fitness facility, and a clubhouse.
Figure 1 – Vicinity Map
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2.3 SITE DISTURBANCE
The site disturbance will occur across roughly 28.2 acres. It is recommended that existing site
condition photos be taken prior to the demolition.
CALCULATIONS CHART
TOTAL DISTURBED PROJECT AREA 28.2 ACRES
TOTAL "ONSITE" AREA OF DISTURBANCE 19.6 ACRES
TOTAL "OFFSITE" AREA OF DISTURBANCE .13 ACRES
TOTAL STORAGE/STAGING AREA 0 ACRES
TOTAL HAUL ROADS AREA N/A
CONSTRUCTION VEHICLE TRAFFIC AREA N/A
EST. PERCENT OF PROJECT AREA EXPOSED 69.5%
EST. PERCENT VEGETATIVE COVER ~2.5% DENSITY
EXISTING SOIL TYPE D
CLAY
LOAM
APPROX. GROUNDWATER DEPTH 6-9 FEET
NUMBER OF PHASES W/ PROJECT N/A
TOTAL VOLUME OF IMPORTED (+) / EXPORTED (-) MATERIALS 70,000 CUB. YD.
TOTAL AREA OF STOCKPILING OF FILL OR BORROW AREAS OFF SITE 0 SQ. FEET
STEEPEST SLOPE 4:1 H:V
DISTANCE FROM A RIPARIAN AREA OR SENSITIVE AREA N/A FEET
2.4 EXISTING TOPOGRAPHIC AND SOIL DATA
In order to complete the associated construction plans, a topographical survey of the site was
completed. This survey consisted of field measurements made by Kumar and Associates in July of
2022.
A NRCS Custom Soil Resource Report of the property indicates that the soil on site is composed of
83.7% Caruso clay loam, and 52.4% Nunn clay loam. Caruso clay loam is considered somewhat
poorly drained and is in hydrologic Soil Group D. Nunn Clay loam is considered well drained and is
hydrologic Soil Group C.
NRCS indicates a wind erodibility rating of 6 (of a scale of 1 to 8, 1 is most susceptible to erosion).
As such this site does not have a high potential for wind erosion. NRCS indicates an erosion factor,
K, of 0.24 – 0.32 (range of 0.02-0.69, 0.69 being more susceptible to sheet and rill erosion). As
such, this site has a moderate susceptibility to sheet and rill erosion.
The topography generally slopes from the west to the east. The site slopes with a mild to moderate
grade (i.e., 0.5 - 1±%) through the interior to a low point located at the northeast of the site.
2.5 RECEIVING WATERS
The property historically drains via overland flow from west to east until it is intercepted by an
abandoned irrigation ditch running along the western third of the site. The ditch flows south, but is
eroded and creates overland flow towards the southeast corner. The remaining uncaptured flow
Table 1 – Construction Activities
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moves west to east until flowing off site or is intercepted by existing drainage in the surrounding
properties. Flows from these properties eventually discharge into the Cache La Poudre River. These
drainage ways will continue to be used as the major receiving waters upon completion of The
Landing at Lemay.
2.6 EXISTING SITE CONDITIONS AND VEGETATION
The existing site consists of existing farm fields and existing drainage channels including an
abandoned irrigation ditch.
There is not a significant amount of grade change on the site.
The existing site vegetation consists of native grasses and invasive weeds. Majority of the site is
exposed farm soil. The existing site does not contain any area of impervious surface. It is highly
recommended that pre-construction photos be taken to clearly document vegetative conditions
prior any disturbance activities.
2.7 EXISTING GROUNDWATER
Groundwater depth was measured onsite in July of 2022 by Kumar & Associates, Inc. with 27
borings and the digging of 6 exploratory test pits at various locations spread throughout the
property (see attached Geotechnical Report). At the time of the last measurement (July, 2022),
groundwater ranged from 7’ to 7.5’ below existing elevations.
2.8 EXISTING GROUND CONTAMINATION
No existing soil or groundwater contamination has been identified at this time.
3.0 PROPOSED CONSTRUCTION ACTIVITIES
3.1 SEQUENCE OF MAJOR ACTIVITIES
To complete the project, many basic categories of construction activity will take place. The first
part will be the removal of the existing concrete and asphalt pavement within the construction
limits of the existing road. Once the existing pavements marked for demo have been removed the
topsoil and native grasses that are currently on-site will be removed. Following topsoil stripping,
rough grading of the proposed roadways and detention/irrigation ponds along with drainage
swales will commence. Next, utility installation including sanitary sewer, water main and storm
sewer. Vertical construction of the bridge will commence after the rough grading and any
stabilization efforts at the of onsite detention ponds has been completed and inspected. New
curb/gutter, paving, and sidewalks are expected to begin after the storm sewer is in place. The
final stages of site construction will be fine grading of the areas mentioned above, and the
installation of landscaping/seeding throughout the project. The aforementioned sequencing is an
initial best guess and is subject to change at the Contractor’s discretion.
This project is proposed to be built in one phase.
Earthwork import to the site is expected to be significant. The site is expected to import fill dirt of
similar geotechnical qualities.
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4.0 GENERAL REQUIREMENTS
4.1 OBJECTIVES
The objective of a Stormwater Management Plan (SWMP) is to identify all potential sources of
pollution likely to occur as a result of construction activity associated with the site construction and
to describe the practices that will be used to reduce the pollutants in stormwater discharges from
the site. The SWMP must be completed and implemented at the time the project breaks ground
and revised as necessary as construction proceeds to accurately reflect the conditions and
practices at the site.
This report summarizes the Stormwater Management Plan for the construction activity that will
occur with The Landing At Lemay in Fort Collins, CO. This plan has been prepared according to
regulations of the Colorado Department of Public Health and Environment (CDPHE), Water Quality
Control Division. This report has been provided to meet the requirements of the City of Fort
Collins Municipal Code §26-498 on water quality control.
4.2 SMWP AVAILABILITY
This report is intended to remain on the construction site to allow for maintenance and inspection
updates and for review during inspection.
4.3 DEFINITIONS
BMP – Best Management Practice encompassing a wide range of erosion and sediment control
practices, both structural and non-structural in nature, intended to reduce or eliminate any
possible water quality impacts from stormwater leaving a construction site.
Erosion Control BMPs – Practices that PREVENT the erosion of soil, such as minimizing the amount
of disturbed area through phasing, temporary stabilization, and preserving existing vegetation.
Sediment Control BMPs – Practices to REMOVE sediment from run-off, such as sediment basins,
silt fence, or inlet protection.
Non-structural BMPs – The implementation of methods, practices, and procedures to minimize
water quality impacts, such as the preservation of natural vegetation, preventive maintenance, and
spill response procedures.
Structural BMPs – Physical devices that prevent or minimize water quality impacts, such as
sediment basins, inlet protection, or silt fence.
4.4 ADDITIONAL PERMITTING
As mentioned above, this Stormwater Management Plan is associated with the Colorado
Department of Public Health and Environment Stormwater Permit that is issued by the Water
Quality Control Division of the CDPHE. Additional Environmental permitting not described in this
report may be required as a part of this project. An example is the Construction Dewatering
Permit for groundwater. Another example is the Air Pollution Emission Notice (APEN). The CDPHE
website contains links to both of these permits, as well as many other potential permits. The
Contractor is responsible for ensuring the proper permits are acquired.
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5.0 ENVIRONMENTAL IMPACT
There are no known environmental impacts to endangered species or other environmentally
sensitive features that have been identified in this project area.
Stormwater outfalls are unlikely to impact wetlands.
6.0 POTENTIAL POLLUTION SOURCES
As is typical with most construction sites, there are several potential pollution sources that could
affect water quality. It is not possible for this report to identify all materials used or stored on the
construction site. It is the sole responsibility of the contractor to identify and properly handle all
materials that are potential pollution sources. Likely pollution sources are marked “YES,” unlikely
pollution sources are marked “NO.” Detailed descriptions of each source are also provided for
additional reference. Please note that not all items with a detailed description are present in the
project, and there could be additional pollution sources that are not listed that must be addressed
by the Contractor.
· YES - Disturbed and stored soils
· YES - Vehicle tracking of soils and sediment
· NO - Management of contaminated soils
· YES - Loading and unloading operations
· YES - Outdoor storage of construction site materials, building materials, fertilizers, chemicals,
etc.
· NO - Bulk Storage of Materials
· YES - Vehicle and equipment maintenance and fueling
· YES - Significant dust or particulate generating processes
· YES - Routine maintenance activities involving fertilizers, pesticides, detergents, fuels,
solvents, oils, etc.
· YES - On-site waste management practices (waste piles, dumpsters, etc.)
· YES - Concrete truck/equipment washing
· NO - Dedicated asphalt and concrete batch plants
· YES - Non-industrial waste sources, such as worker trash and portable toilets
· YES - Saw Cutting and Grinding
· NO - Material Handling and Spill Prevention
· NO - Non-Stormwater Discharges including construction dewatering not covered under the
Construction Dewatering Discharges general permit and wash water that may contribute to
pollutants to the MS4
6.1 DISTURBED AND STORED SOILS
Approximately 19.6 acre of the site will be disturbed with the Construction Activities. Once soils
have been disturbed they do not retain the same compaction as in their native state, therefore
surface runoff can cause more soil erosion than was historically observed. In the event that these
erosion control practices do not keep sediment on site a structural barrier (silt fence) will be used
and is called out for on the perimeter. If soil manages to migrate from the disturbed areas onto the
hard surfaces it will be swept or scraped (street sweeping) to prevent the migration of sediment. In
case that sediment is washed away too quickly the curb inlets will need protection (rock sock style
inlet protection).
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Soil stockpiles are expected on this site. Stockpiles in the same respect do not retain the same
compaction and are more susceptible to soil erosion. Stockpiles on this site shall be placed in or
near the center of the site and away from any drainage swales to not require perimeter run off
controls (Materials/Site Management Control). The stock pile will be kept loose, not compacted,
and watered as needed to prevent dust issues (site watering). The stockpile will be monitored for
signs of erosion displacement and sediment accumulation and if conditions warrant it, the
stockpile will be structurally covered or if it is going to sit a long while will be reseeded (temporary
seeding).
6.2 VEHICLE TRACKING OF SEDIMENT
Vehicle tracking of sediment may occur throughout the construction process and along all areas
where the pavement meets the disturbed dirt. This occurs most often after any melt off or rain
conditions when mud collects on vehicles tires and is tracked out onto the road consequently
leaving site. This increases the possibility of sediment discharging to the storm system. To prevent
tracking, access to the site will be limited to construction entrances (vehicle tracking pads to be
installed) on the southwest side of the site and northeast side of the site. Vehicle access will be
limited on muddy days (site management control), in this case parking will be kept to the stabilized
staging area. The tracking pad will be monitored visually every day and if track-out becomes a
significant problem a larger or more robust tracking pad may be installed. Otherwise, all track-out
that reaches the street will be scraped and swept (street sweeping). Secondary controls at the
closest affected inlets will have protection (inlet protection) to capture sediment not swept up in a
timely manner.
Additional measures can be taken to minimize and control sediment discharges from the site due
to vehicle tracking. These measures can include fencing around the site to control access points.
The use of gravel parking areas and wash racks can also be implemented to ensure minimal vehicle
tracking from the site.
6.3 MANAGEMENT OF CONTAMINATED SOILS
All data about the site shows that there is no known contamination on the site. If encountered, the
contractor will have the material stored in a covered area (materials management control) as to not
mix with the stormwater until the material can be identified and proper classification and disposal
methods can be determined in accordance with the various waste laws and with good construction
safety and practices.
6.4 LOADING AND UNLOADING OPERATIONS
There is not anticipated to be a significant amount of export leaving the site.
During this project there will be a diverse amount of loading and unloading. The foundation
workers will have to deliver forms to the site and deliver premixed concrete. Landscapers will have
to pile the materials on site to complete the landscape work. Though the loading and loading
vehicles will be contributing to the track out of materials, depending on the material being
delivered to the site they may have a significant spill potential. Where the trailers must access the
site an attempt will be made to keep the vehicle on the VTC or other stabilized storage areas.
When loading and unloading is occurring, depending on the materials, there may be an increased
problem of containers being dropped, punctured, or broken. These off-loading activities will be
located away from storm drains and will have nearby spill kits accessible. Spills on site will be
addressed using spill prevention and response procedures.
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6.5 OUTDOOR STORAGE OF CONSTRUCTION SITE MATERIALS, BUILDING MATERIALS,
CHEMICALS, ETC.
It is anticipated that inert material like wood, tiles, and stone will be stored on site and outside in
the elements. It is also anticipated that materials that do not weather well (cement, mortar, etc.)
will also be located outside. Chemicals are not anticipated to be left outside. As the inert materials
have a lower potential to leave the site they will be monitored during inspection to make sure they
are not being impacted by the exposure to the elements (site management control). The materials
that will need added attention are the cements and mortars as they quickly mix with water and
cause pollution issues. These materials when not stored inside will be placed on pallets to get
above potential surface runoff and covered with tarps or plastic to prevent mixing with stormwater
(materials management control). Very small quantities of chemical are needed to contaminate
stormwater so the fertilizers, paints, form oils, petroleum products, and other typical chemicals, will
be stored in the construction connex box, trailers, vehicles, or the like out of contact with
precipitation (materials management control). If not stored in a location as described, secondary
containment will be required. The contractor shall clearly designate site areas for staging and
storage of building materials.
6.6 BULK STORAGE OF MATERIALS
This site is not expected to store bulk liquid chemicals of more than 55 gallon drums. If this site
does have the need to store liquid chemicals the following procedure should be followed.
These materials should be stored in an area that if a rupture would occur, it would be contained.
The area will need to be located away from the drainage areas and area inlets (site management /
materials management). The containers will be stored in secondary containment area with a fence
so that if a spill were to happen, it would pool in the bottom of the area and be contained.
6.7 VEHICLE AND EQUIPMENT MAINTENANCE AND FUELING
Based on the size of the site and the duration of activities vehicle fueling and vehicle maintenance
is highly likely. As fueling and equipment maintenance usually result in small spills of petroleum
products it is important to monitor these activities carefully. (site management control) Some
grading companies will employee a fuel truck to fill the heavy equipment on site or require the
maintenance of a broken machine. In those cases where the vehicle is not able to be maintained
off site, these activities will be done in the least detrimental way possible. The maintenance and
fueling will be located as far from stormwater features as possible and at least 50 feet from a
stormwater feature (site management/materials management). The fueling activity will have spill
materials nearby and a bucket or other container and shovel located nearby to hang a hose after
filling to catch drips, and to scoop up any dirt that inadvertently mixed with the soil (materials
management). That container will have a lid and be disposed of when the activity is completed.
The maintenance work will be done on a tarp or other material to prevent the residual oils and
greases from mixing with the dirt (materials management). A clearly designated on-site fueling
and maintenance area is suggested
6.8 SIGNIFICANT DUST OR PARTICULATE GENERATING PROCESSES
This project will result in earth moving activities, street sweeping, and track-out and carry out, bulk
materials transport, and saw cutting. As these activities will result in offsite transport of
atmospheric pollution reasonable precautions shall be taken. The project will follow all required
“BMPs” articulated in the Fugitive Dust Manual and a least one additional BMP included during
each of the identified activities in accordance with City Ordinance No. 044 2016. Also a copy of the
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Dust Control Manual will be kept in the trailer during construction for reference. Such activities will
include but not limited to watering the site, covering trucks, slower site speeds and vehicle tracking
mentioned above.
6.9 ROUTING MAINTENANCE ACTIVITIES INVOLVING FERTILIZER, PESTICIDES,
DETERGENTS, FUELS, SOLVENTS, OILS
Fertilizers and Pesticides will be used during the later phases of the project when trying to
establish a healthy vegetation. These chemicals are highly water soluble and are easily and
unnoticeably carried in the stormwater. Proper application rates and recommended timing of
application will be strictly followed and not on days, or the next day, where the weather is calling
for precipitation (materials management control). As most of these types of chemicals will be
brought on by the landscaper they will be required to keep these products in their vehicles until
time of application and not be allowed to leave these materials on the site (site management
control). If these materials are stored on site they shall be kept inside or outside covered and
above the ground to prevent the materials from mixing with water and runoff (materials
management control). Detergents, paints, acids, cement, grout, and solvents will be prevalent in
the interior work of the building (materials management). These materials also are typically easily
mixed with water yet are typically noticeable by discolored, cloudy, or sudsy water. As such, the
contractor will always keep an eye out for these types of differences in water around the site (site
management control). However these materials are to be handled, operated, and cleaned up all
within the inside of the structure, where external use is concerned these materials will be stored in
the construction connex box, trailers, vehicles, or the like out of contact with precipitation
(materials management). If not stored in a location as described secondary containment will be
required (materials management). Fuels and oils might be associated with the smaller equipment
used on site, chainsaws, pumps, generators, etc. As petroleum products are easily suspended in
water and are spread across the top of the water surface. These products when located in water
have rainbow sheen on them. They are also monitored during construction (site management
controls). These products will be stored in the construction connex box, trailers, vehicles, or similar
structure that will minimize contact with precipitation (materials maintenance controls). If not
stored in a location as described secondary containment will be required (materials maintenance).
Any untreated runoff from these activities can be detrimental to wildlife if not cleaned up.
6.10 ON-SITE WASTE MANAGEMENT PRACTICES
All large and heavy weighted waste piles (concrete chunks, excavated pipes, etc.) will be kept in a
neatly grouped pile until the material is to be disposed of properly. These piles will only be stored
the shortest duration possible and will be kept 50 feet from any drainage course or inlet
(Administrative Control). All dry wastes will be maintained through dumpsters and monthly hauler
removal (hauler will be notified if dumpster becomes full and hauled off as needed). Where
available by the hauling company the dumpster will be covered. If not practical or available by the
haul company, an increased removal schedule will be followed and the “Max fill line” on the
dumpster will be strictly followed. Corners of the dumpsters will be monitored for “Dumpster Juice”
leaking into the soil in dry conditions and rain/melt off conditions looking for it mixing with the
runoff. Dumpsters, like the waste piles, will be located at least 50 feet from any drainage course or
inlet. Workers will be sent around at the end of the day to collect trash to prevent trash being left
out overnight. No construction debris (including broken concrete) will be buried on site.
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6.11 CONCRETE TRUCK/EQUIPMENT WASHING
Concrete will be a portion of this project. It is anticipated that it will be used with the joints around
the manholes, pour in place inlets, curb and gutter installation, sidewalks and bridge construction.
Pre mixed concrete trucks will be used in this process and will be delivered to the site and when
pouring the bridge components. Washing of the concrete equipment will be required to maintain
the concrete equipment. This concrete wash water has a high alkaline content which is hazardous
material to terrestrial and aquatic wildlife. A section of dirt near the entrance will be excavated and
compacted around the sides formed to retain the concrete wash water on site (as an acceptable
practice by the State) so long as the wash water is kept in the washout (concrete washout). There
will be a rock pad for the truck to park on while washing as to prevent tracking from this washout
(VTC). The placement of this washout will be located at least 50 feet from any drainage course or
inlet. Later in the project after the parking lots curb and gutter has been poured the use of a
mobile washout facility will be used on site in a similar location and after the ground has been
leveled (concrete washout – mobile). The contractor (including all masonry and concrete
tradesmen) shall clean out equipment within the washout area so that the runoff is not allowed to
leave the washout. The only exception would be for them to wash in the next day’s pour location.
All concrete workers will be made aware of the where they are to wash (site management controls
& education). If there is a significant amount of spillage when the transfer from concrete truck to
pump truck occurs, a tarp or other ground cloth should be used to collect spillage. (ground cover
control).
6.12 DEDICATED ASPHALT AND CONCRETE BATCH PLANTS
There will be no dedicated asphalt or concrete batch plants erected onsite for this project.
Premixed concrete and paving materials will be delivered to the site and placed.
In the event that a plant is needed, the Contractor should be aware that additional permitting will
be required. In particular, an Air Pollutant Emission Notice (APEN) will need to be obtained from
the CDPHE.
6.13 NON-INDUSTRIAL WASTE SOURCES SUCH AS WORKER TRASH AND PORTABLE
TOILETS
Since facilities are not located nearby for workers to use, trash and sanitary facilities will be
required on the site.
Worker trash will be comingled with the industrial trash and will follow the same controls with the
caveat that a trashcan will be located near the entrance of the site as the contractor will need to
dump their trash from lunch, etc. and this will be emptied weekly or more frequently, if needed.
Designate trash and bulk waste collection areas on-site. Dumpsters should be located near site
entrances to minimize traffic on disturbed soils, and they should be placed on a level soil surface.
When possible, materials should be recycled. Hazardous material waste should be segregated
from other solid waste.
If tipped over and when being cleaned, portable toilet facilities become a potential discharge if not
cleaned up. If human waste is spilled, it will need to be treated as a biological hazard of untreated
sewage and will need to be cleaned up in accordance with Larimer County Health Department
Guidance. The toilets will be staked in a way to prevent tipping on a dirt surface and located at
least 50 feet from a drainage course or inlet. If the site cannot accommodate a portable toilet on
dirt, a containment pan or other secondary containment will be provided. They will also be
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anchored prevent from tipping. All materials shall be properly disposed of in accordance with the
law.
6.14 SAW CUTTING AND GRINDING
The trench work and street connections will require cutting into the City street. This project will
need the use of hardened saws. These saws generate a significant amount of dust. Watering the
cutting surface to prevent airborne particulates (BMP in the City’s Fugitive Dust Manual) is
required. The cutting slurry has a high content of fine particulates (Silica Dust, Metals, etc.) that is
not allowed to discharge as runoff from the site. To prevent slurry from discharging offsite,
contractors will use the minimum amount of water needed to prevent dust and blades from
overheating (site management control). Cutting slurry will be collected via vacuum or allowed to
dry out and be scraped and swept up after the cutting has finished (saw cutting).
The following protocol is recommended to prevent dust and slurry from asphalt and concrete saw
cutting activities from migrating into the existing storm drain system.
· Slurry and cuttings shall be vacuumed during cutting and surfacing operations
· Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight
· Slurry and cuttings shall not drain to any natural or constructed drainage conveyance
· Collected slurry and cuttings shall be disposed of in a manner that does not violate
groundwater or surface water standards
6.15 MATERIAL HANDLING AND SPILL PREVENTION
Potential pollution sources, as discussed in earlier sections, are to be identified by the contractor.
Spill prevention procedures are to be determined and put in place before construction by the
contractor. A spill and flooding response procedure must also be determined and put in place
before construction by the contractor. Additionally, steps should be taken to reduce the potential
for leaks and spills to come in contact with stormwater run-off, such as storing and handling toxic
materials in covered areas or storing chemicals within berms or other secondary containment
devices.
A notification procedure must be put in place by the contractor, by which workers would first
notify the site construction superintendent, who would then notify the SWMP Administrator.
Depending on the severity of the spill, the site construction superintendent and SWMP
Administrator would possibly notify the Colorado Department of Public Health and Environment -
Water Quality Control Division, downstream water users, or other appropriate agencies. The
release of any chemical, oil, petroleum product, sewage, etc., which enter waters of the State
of Colorado (which include surface water, groundwater, and dry gullies or storm sewers
leading to surface water) must be reported immediately to the Division’s emergency spill
reporting line at (877) 518-5608. All spills requiring cleanup, even if the spill is minor and does
not need to be reported to the State, should still be reported to the City of Fort Collins Utilities
office at 970-221-6700.
It will be the responsibility of the Contractor to designate a fueling area and take the necessary
precautions to ensure that no stormwater pollution occurs in the event that a fueling area is
needed. Fueling areas shall be located a minimum 100 feet from all drainage courses. A 12-inch
high compacted earthen ridge capable of retaining potential spills shall enclose fueling areas.
Other secondary containment devices can be used instead of the earthen ridge. The area shall be
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covered with a non-porous lining to prevent soil contamination. Printed instructions for cleanup
procedures shall be posted in the fueling area and appropriate fuel absorbents shall be available
along with containers for used absorbents within the fueling area.
6.16 NON-STORMWATER DISCHARGES, INCLUDING CONSTRUCTION DEWATERING NOT
COVERED UNDER THE CONSTRUCTION DEWATERING DISCHARGES GENERAL
PERMIT AND WASH WATER THAT MAY CONTRIBUTE TO POLLUTANTS TO THE MS4
The Stormwater Construction Permit only covers discharges composed entirely of stormwater. The
discharge of pumped stormwater, ONLY, from excavations, ponds, depressions, etc. to surface
waters, or to a municipal storm sewer system is allowed by the Stormwater Construction Permit, as
long as the dewatering activity and associated BMPs are identified in the Stormwater Management
Plan (SWMP) and are implemented in accordance with the SWMP.
Aside from the exceptions noted above, non-stormwater discharges must be addressed in a
separate permit issued for that discharge. If groundwater is encountered, and dewatering is
required, a Construction Dewatering Permit must be acquired from the Colorado Department of
Public Health and Environment.
Based upon a subsurface exploration report done in 2022 by Kumar & Associates, Inc., ground
water levels indicate that it may be present during construction of sanitary sewer at 6-9’ deep. If
encountered, dewatering activities may be required. Groundwater has in most excavations mixed
with the dirt and as they are pumped, they will add an increased velocity coming out of the out
flow end contributing to erosion and speeding the transport of the suspended sediment particles.
Also, construction dewatering activities must be identified in the Erosion Control Report if they are
to be infiltrated on site. If the material is anticipated to be pumped to a stormwater conveyance
the proper Construction Dewatering Permit must be pulled from the State of Colorado. If pumping
activities are to occur on the site, the use of rock packs on the intake end of the pump will be used
and a silt bag will be used on the outflow end of the pump to reduce the silt and sediment from
leaving the activity (dewatering Control Measure). If this will be under a Dewatering Permit water
samples will be collected in accordance with that permit.
7.0 CONTROL MEASURES
7.1 SWMP ADMINISTRATOR
A SWMP Administrator must be designated in conjunction with the Stormwater Permit. This person
shall be responsible for developing, implementing, maintaining, and revising the SWMP. The
SWMP Administrator will also be the contact for all SWMP-related issues and will be the person
responsible for the accuracy, completeness, and implementation of the SWMP. The Administrator
should be a person with the authority to adequately manage and direct day-to-day stormwater
quality management activities at the site.
The Landowner of this site is:
Name: (to be filled in by permittee)
Company: (to be filled in by permittee)
Phone: (to be filled in by permittee)
E-mail: (to be filled in by permittee)
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The SWMP Administrator for this site is:
Name: (to be filled in by permittee)
Company: (to be filled in by permittee)
Phone: (to be filled in by permittee)
E-mail: (to be filled in by permittee)
The Contractor for this site is:
Name: (to be filled in by permittee)
Company: (to be filled in by permittee)
Phone: (to be filled in by permittee)
E-mail: (to be filled in by permittee)
The Developer for this site is:
Name: (to be filled in by permittee)
Company: (to be filled in by permittee)
Phone: (to be filled in by permittee)
E-mail: (to be filled in by permittee)
The Erosion Control Administrator for this site is:
Name: (to be filled in by permittee)
Company: (to be filled in by permittee)
Phone: (to be filled in by permittee)
E-mail: (to be filled in by permittee)
7.2 BEST MANAGEMENT PRACTICES (BMPS) FOR STORMWATER POLLUTION
PREVENTION
Beginning from mobilization, and throughout the entire construction of the project, erosion
control devices shall be installed to ensure minimal pollutant migration. These erosion control
devices may be installed in phases, or not at all, depending on actual conditions encountered at
the site. It is the responsibility of the Contractor to make the determination as to what practices
should be employed and when. In the event that a review agency deems BMPs to be insufficient, it
shall be the responsibility of the contractor to implement modifications as directed.
Best Management Practices (BMPs) are loosely defined as a method, activity, maintenance
procedure, or other management practice for reducing the amount of pollution entering a water
body. The term originated from rules and regulations in Section 208 of the Clean Water Act.
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Details for Structural and Non-Structural BMPs have been included in Appendix B. These details
should be used for additional information on installation and maintenance of BMPs specified in
this report. It is also intended to serve as a resource for additional BMPs that may be appropriate
for the site that have not specifically been mentioned in the report.
7.3 STRUCTURAL PRACTICES FOR EROSION AND SEDIMENT CONTROL
Structural BMPs are physical devices that are implemented to prevent erosion from happening or
to limit erosion once it occurs. These devices can be temporary or permanent, and installation of
individual components will vary depending on the stage of construction.
A table depicting construction sequence and BMP application/removal has been placed on the
“Dynamic Site Plan” to help document the implementation of these BMPs. Refer to the
Stormwater Management Plan Static Site Plan in the Appendix for the assumed location of all
BMPs. Construction Details for Temporary BMPs are located in the Appendix for reference.
Again, the final determination for which BMP’s will be installed, where they will be located, and
when they will be installed shall be made by the Contractor, along with all documentation
throughout the construction process.
Silt Fencing (Phase I)
Silt fencing shall be provided to prevent migration of sediment off-site or into adjacent properties.
All silt fencing shall be installed prior to any land disturbing activity (demolition, stockpiling,
stripping, grading, etc.). Silt fencing is to be installed prior to site excavation or earthwork
activities.
Inspections of the silt fence should identify tears or holes in the material and should check for
slumping fence or undercut areas that allow flows to bypass the fencing. Damaged sections of the
silt fence should be removed to maintain BMP effectiveness, typically before it reaches a depth of 6
inches.
It is suggested that silt fencing be located along the North and East bounds of the disturbed areas
of the site, with an exception for the existing road (Link Lane) intersection at the northeast corner
of the disturbed areas. Refer to the Erosion Control Plan (Sheet C 300 through C 304) for additional
clarification.
Sediment Control Log – aka “Straw Wattles” (Phase I)
A Sediment Control Log is a linear roll made of natural materials, such as straw, coconut fiber, or
other fibrous material trenched into the ground and held with a wooden stake. Sediment Control
Logs can be used in many instances. Examples include perimeter control for stockpiles, as part of
inlet protection designs, as check dams in small drainage ways, on disturbed slopes to shorten flow
lengths, or in lieu of silt fencing (where appropriate).
Sediment Control Logs should be inspected for excess sediment accumulation. Sediment should
be removed prior to reaching half the height of the log.
At a minimum, Sediment Control Logs should be used around soil stockpiles (including landscape
material) and at all stormwater discharge locations other than inlets. All proposed landscape
swales, including ones discharging into detention ponds shall have a straw wattle installed
perpendicular to flow every 4” of elevation difference. Refer to the Erosion Control Plan (Sheet C
300 through C 304) for additional clarification.
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Vehicle Tracking Control Pads (Phase I)
Vehicle tracking control pads shall be provided to minimize tracking of mud and sediment onto
paved surfaces and neighboring roadways. All vehicle tracking control pads shall be installed prior
to any land disturbing activity (demolition – as necessary, stockpiling, stripping, grading, etc.).
Location of vehicle tracking control pads will be located at any and all existing and future vehicle
accesses being used during any of the construction phases. These locations will primarily be
dictated by gates or openings in the temporary construction fencing that is expected to be
installed. Vehicle tracking control pads are to be installed prior to demolition (as appropriate), site
excavation or earthwork activities.
Vehicle tracking pads should be inspected for degradation and aggregate material should be
replaced as needed. If the area becomes clogged with water, excess sediment should be removed.
Aggregate material should remain rough, and at no point should aggregate be allowed to
compact in a manner that causes the tracking pad to stop working as intended.
Suggested location for vehicle tracking pad is at the proposed access on the south of the site off
Duff Drive. Refer to the Erosion Control Plan (Sheet C 300 through C 304) for additional
clarification.
Inlet Protection (Phase I & II)
Inlet protection shall be provided for existing inlets to prevent sediment transport from adjacent
earthwork disturbance. Installation of these filters shall occur before adjacent earth disturbing
activities (Phase I implementation). Wattle type filters are to be implemented for new and existing
inlets where asphalt does not exist. For these inlets, if pavement is constructed adjacent to the
structure or if the area adjacent to the inlet is changed such that the wattle type filter is no longer
effective, it shall be the responsibility of the Contractor to ensure that an appropriate method is
used instead. For example, the wattle filter could be reused, or a gravel-block inlet filter may be
installed. It will be left to the discretion of the Contractor as to whether replacement of any inlet
filter is necessary.
Inlet protection should be inspected regularly for tears that can result in sediment entering an
inlet. Inlet protection should also be inspected for sediment accumulation upstream of the inlet,
and sediment should be removed when the less than half of the capacity is available, or per
manufacturer specifications.
All proposed curb inlets along proposed roadways and upstream flared end sections shall have
inlet protection. Refer to the Erosion Control Plan (Sheet C 300 through C 304) for additional
clarification.
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Turf Reinforcement Mat (Phase II)
Turf Reinforcement Mats are utilized at the end of storm drain flared end sections to prevent
scouring and erosion of the soils at the edges of the pipe. Turf Mats will be installed after seeding
of the surrounding areas to allow for grass to take root and ensure easy anchoring of the mats.
Turf Reinforcement Mats should be inspected regularly and replaced if becoming too worn down
to calm flows through the drainage. Turf Reinforcement Mats shall be sized according to the
specifications of the manufacturer as listed in the table on sheet C 304 of the Erosion Control Plan.
Refer to the Erosion Control Plan (Sheet C 300 through C 304) for details regarding specific
placement and specifications for Turf Reinforcement Mats.
Erosion Control Blankets (Phase II)
A temporary degradable rolled erosion control product composed of natural flexible fibers shall be
used on all seeded slopes 4:1 and greater (excluding mulched shrub bed areas). Erosion control
blankets should be utilized to provide erosion control and to facilitate vegetation establishment.
During installation, it is important to ensure that no gaps or voids exist under the material and that
all corners of the material are secured using stakes and trenching. Stakes should be made of
materials that are biodegradable. Continuous contact between the product and the soil is
necessary to avoid failure.
Erosion Control Blankets should be inspected regularly for signs of erosion, including beneath the
mat. If voids are apparent, they should be filled with suitable soil. Inspections should also identify
loose or damaged stakes, as well as loose portions of the blanket. If deficiencies are found, they
should be repaired or replaced.
Concrete Washout Area (Phase II)
A concrete washout should be provided on the site. The washout can be lined or unlined
excavated pits in the ground, commercially manufactured prefabricated containers, or
aboveground holding areas. The concrete washout must be located a minimum of 400 feet from
any natural drainage way or body of water, and at least 1000 feet from any wells or drinking water
sources. Washout areas should not be located in an area where shallow groundwater may be
present. Contractor shall clearly show the desired location and access to the Concrete Washout
Area on the Stormwater Management Plan - Dynamic Site Plan. Contractor shall place a Vehicle
Tracking Pad if the selected location for the Concrete Washout Area is detached from pavement.
Clear signage identifying the concrete washout should also be provided.
The Concrete Washout Area should be inspected regularly. Particular attention should be paid to
signage to ensure that the area is clearly marked. Confirmation that the washout is being used
should also be noted to ensure that other undesignated areas of the site are not being used
incorrectly as a concrete washout.
It is suggested the Contractor build a concrete wash out pit for this project. It is recommended that
the concrete wash out pit be placed north to the vehicle tracking pad at the southwestern most
entrance to the site. This location is to ensure minimum distance from wash out to exiting the site
while maintaining a minimum of 400’ from any inlets to existing storm drains or constructed
connections to the existing storm drains. The location shown in the Erosion Control Plan (Sheet C
302) is only a suggestion and can be relocated at the discretion of the Contractor.
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Permanent/Established Vegetation (Phase IV)
Permanent or established vegetation and landscaping is considered a permanent form of sediment
and erosion control for common open spaces, steep slopes and areas not exposed to prolonged
scour velocities, or acute incipient motion bed shear stresses that will create soil erosion, rill
formation and subsequent sediment transport. Areas where the previous conditions apply will
contain sufficient permanent BMPs, such as riprap or cobble mulch. Permanent vegetation shall
conform to the approved Landscape Plan prepared by Ripley Design Inc. Permanent/Established
vegetation and hardscape defines Phase IV of development.
7.4 NON-STRUCTURAL PRACTICES FOR EROSION AND SEDIMENT CONTROL
Non-Structural BMPs are practices or activities that are implemented to prevent erosion from
happening or to limit erosion once it occurs. These BMPs can be a practice resulting in physical
change to the site, such as mulching or slope stabilization. They can also result in behavioral
changes on the site, such as changes to construction phasing to minimize exposure to weather
elements, or increased employee awareness gained through training.
Protection of Existing Vegetation (Phases I-IV)
Protection of existing vegetation on a construction site can be accomplished through installation
of a construction fence around the area requiring protection. In cases where up-gradient areas are
disturbed, it may also be necessary to install perimeter controls to minimize sediment loading to
sensitive areas such as wetlands.
Trees that are to remain after construction is complete must be protected. Most tree roots grow
within the top 12”-18” of soil, and soil compaction is a significant threat to tree health. As such,
particular care should be taken to avoid activities within the drip-line of the tree. Direct equipment
damage should also be prevented. The most effective way to ensure the health of trees is to
establish a protection zone at the drip-line of the tree to prevent unintended activity in the area
directly surrounding the tree.
Fencing should be inspected and repaired when needed. If damage occurs to a tree, an arborist
should be consulted on how to care for the tree. If a tree is damage beyond repair, the City
Forester should be consulted on remediation measures.
At a minimum, protection to all trees identified for retention on the plans by Ripley Design Inc.
Stockpile Management (Phases I-III)
Stockpile management should be utilized to minimize erosion and sediment transport from soil
stockpiles. In general, soil stockpiles should be located a minimum of 100 feet from any drainage
way and 50 feet from any storm sewer inlets. Where practical, choose a stockpile location that will
remain undisturbed for the longest period of time as the phases of construction progress.
Sediment control BMPs should be placed around the perimeter of the stockpile, and a designated
access point on the upstream side of the stockpile should be identified. BMPs such as surface
roughening, temporary seeding, mulching, erosion control blankets, or soil binders should be used
to stabilize the stockpile surface.
As a part of stockpile management, regular inspections of the perimeter controls should be
completed. If BMPs have been utilized to stabilize the surface of the stockpile, they should be
inspected and repaired as needed.
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While soil stockpiles are not expected with this project, it is possible that foundation excavation or
the delivery landscaping material may generate temporary stockpiles. The location of any such
stockpiles shall be the responsibility of the SWMP Administrator.
Mulching (Phase I-III)
Mulching helps reduce erosion by protecting bare soil from rainfall impact, increasing infiltration,
and reducing runoff. Although often applied in conjunction with temporary or permanent seeding,
it can also be used for temporary stabilization of areas that cannot be reseeded due to seasonal
constraints. The most common type of mulch used is hay or grass that is crimped into the soil to
keep it secure. However, crimping may not be practical on slopes steeper than three to one
(3H:1V).
The Contractor shall mulch all planted areas within twenty-four (24) hours after planting. Only
weed-free and seed-free straw mulch may be used. Straw mulch should be applied at two (2) tons
per acre, and shall be adequately secured by crimping, tackifier, netting or blankets. Hydraulic
mulching may also be used on steep slopes or where access is limited. In the case that hydraulic
mulching is utilized, the Contractor shall use wood cellulose fibers mixed with water at two
thousands to two thousand five hundred (2,000-2,500) pounds per acre and organic tackifier at
one hundred to four hundred (100-400) pounds per acre.
The Contractor is responsible in applying wood chip mulch to all planted trees and shrubs as
shown on the Landscape Plan prepared by Ripley Design Inc.
Wind Erosion/Dust Control (Phase I-IV)
Wind Erosion and Dust Control BMP’s help to keep soil particles from entering the air as a result of
land disturbing construction activities. Attached at the end of the Appendix B is the Fort Collins
Dust Prevention and Control Manual. The purpose of this manual is to establish minimum
requirements consistent with nationally recognize BMP’s for controlling fugitive dust emissions and
to describe applicable best management practices to prevent, minimize, and mitigate off-property
transport or off-vehicle transport of fugitive dust emissions pursuant to Chapter 12, Article X of the
Fort Collins City Code (§12-150 et. seq) for specific dust generating activities and sources. Examples
include use of a water truck or irrigation/sprinkler system to wet the top layer of disturbed soil,
seeding and mulching, soil binders, or wind fences.
Please refer to the last three pages of Appendix B for the Dust Control Plan. A Dust Control Plan is
required for all development projects or construction sites with greater than five (5) acres in size.
Street Sweeping (Phases I -IV)
Street sweeping should be used to remove sediment that has been tracked onto adjacent
roadways. Roadways should be inspected at least once a day, and sediment should be removed as
needed. A check of the area inlet protection should be completed after sweeping to ensure
nothing was displaced during sweeping operations. Street sweeping can reduce the sediment
washed into the existing storm drain system. Street sweeping may be necessary on the existing
hardscape areas which receive runoff from the disturbed areas.
Good Housekeeping Practices (All phases)
Good housekeeping practices that will prevent pollution associated with solid, liquid, and
hazardous construction-related materials and wastes should be implemented throughout the
project. Examples of good housekeeping include providing an appropriate location for waste
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management containers, establishing proper building material staging areas, designating paint
and concrete washout areas, establishing proper equipment/vehicle fueling and maintenance
practices. Development of a spill prevention and response plan is another example of Good
Housekeeping practices that should be used on the project. The following items are detailed
examples of some of the good housekeeping practices that should be utilized throughout the
project. It should be noted that a complete list of practices and detailed discussion regarding
good housekeeping has been included within the Potential Pollution Sources section of this report.
Street Sweeping and Vacuuming – Street sweeping and vacuuming should be used to remove
sediment that has been tracked onto adjacent roadways. Roadways should be inspected at least
once a day, and sediment should be removed as needed. A check of inlet protection should be
completed after sweeping to ensure nothing was displaced during sweeping operations.
Waste Management – Designate trash and bulk waste collection areas on-site. When possible,
materials should be recycled. Hazardous material waste should be segregated from other solid
waste. Waste collection areas should be located away from streets, gutters, watercourses, and
storm drains. Dumpsters should be located near site entrances to minimize traffic on disturbed
soils, and they should be placed on a level soil surface.
Establish Proper Building Material Handling and Staging areas – Clearly designate site areas for
staging and storage of building materials. Provide appropriate BMPs to ensure that spills or leaks
are contained.
Establish Proper Equipment/Vehicle Fueling and Maintenance Practices – If needed, create a clearly
designated on-site fueling and maintenance area that is clean and dry. Provide appropriate BMPs
to ensure that spills or leaks are contained.
7.5 PHASED BMP INSTALLATION AND REMOVAL
It is important to recognize the four (4) major Development Phases as defined by the State of
Colorado’s Stormwater Discharge Permit (SDP). These four development phases (referred to as
Sequencing by the City of Fort Collins) have been distinguished to aid in the appropriate timing of
installation/ implementation of BMPs at different stages of the construction process. These phases
are described as follows:
Phase I – Demolition Stage; BMPs for initial installation of perimeter controls
Phase II – Infrastructure Stage; BMPs for utility, paving, and curb installation
Phase III – Vertical Construction Stage; BMPs for individual building construction.
Phase IV – Permanent BMPs and final site stabilization.
The following is a rough estimate of the anticipated construction sequence for site improvements.
The schedule outlined below is subject to change as the project progresses and as determined by
the General Contractor.
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Table 2 – Preliminary Permit and Construction Schedule
Included in the back map pockets are two Site Plans: a “Static” Site Plan and a “Dynamic” Site Plan.
The “Static” plan serves to display the overall management plan all at once. However, proper
implementation of BMPs does not occur at once, and certain BMPs may move location in the
construction process; therefore, the “Dynamic” Site Plan is intended for the contractor to write in
the BMP symbols to document the location and time the BMPs are installed and maintained
throughout the entire construction process.
BMP Removal shall be in accordance with Table 3 detailing each stage an individual BMP will be
used when applicable and in which stage it should be removed. Some BMPs are simply practices
and should be observed and followed during the duration of the project, such as dust reduction.
Table 3 – Construction Sequence and BMP Application
7.6 BMP INSPECTION
All temporary erosion control facilities shall be inspected at a minimum of once every two (2)
weeks and after each significant storm event or snowmelt. Repairs or reconstruction of BMPs, as
necessary, shall occur as soon as possible to ensure the continued performance of their intended
function. It is the responsibility of the SWMP Administrator to conduct bi-weekly inspections,
TASK
BEGINNING
DATE ENDING DATE "BMP-PHASE OF
DEVELOPMENT"
Development Construction Permit
Issued by City of Fort Collins I
Overlot Grading (Demolition) I
Utility Installation II
Road Construction III
Final Stabilization IV
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maintain BMPs if needed, keep records of site conditions and inspections, and update the SWMP
as necessary.
The construction site perimeter, disturbed areas, all applicable/installed erosion and sediment
control measures, and areas used for material storage exposed to precipitation shall be inspected
for evidence of, or the potential for, pollutants entering the drainage system. Erosion and sediment
control measures identified in the SWMP shall be observed to ensure they are operating correctly.
Attention should be paid to areas with a significant potential for stormwater pollution, such as
demolition areas, concrete washout locations, and vehicle entries to the site. The inspection must
be documented to ensure compliance with the permit requirements.
7.7 BMP MAINTENANCE
Any BMPs not operating in accordance with the SWMP must be addressed as soon as possible,
immediately in most cases, to prevent the discharge of pollutants. If modifications are necessary,
such modifications shall be documented so that the SWMP accurately reflects on-site conditions.
The SWMP needs to accurately represent field conditions at all times.
Uncontrolled releases of mud, muddy water, or measurable amounts of sediment found offsite will
be recorded with a brief explanation of the measures taken to clean up the sediment that has left
the site, as well as the measures are taken to prevent future releases. This record shall be made
available to the appropriate public agencies (Colorado Department of Public Health and
Environment, Water Quality Control Division; Environmental Protection Agency; City of Fort Collins;
etc.) upon request.
Preventative maintenance of all temporary and permanent erosion control BMPs shall be provided
to ensure the continued performance of their intended function. Temporary erosion control
measures are to be removed after the site has been sufficiently stabilized, as determined by the
City of Fort Collins. Maintenance activities and actions to correct problems shall be noted and
recorded during inspections.
Inspection and maintenance procedures specific to each BMP identified with this SWMP are
discussed in Section 3. Details have also been included in Appendix B.
7.8 RECORD KEEPING
Documentation of site inspections must be maintained. The following items are to be recorded
and kept with the SWMP:
· Date of Inspection
· Name(s) and title(s) of personnel making the inspection
· Location(s) of sediment discharges or other pollutants from the site
· Location(s) of BMPs that need to be maintained
· Location(s) of BMPs that failed to operate as designed or proved inadequate
· Locations(s) where additional BMPs are needed that were not in place at the time of
inspection
· Deviations from the minimum inspection schedule
· Descriptions of corrective action taken to remedy deficiencies that have been identified
· The report shall contain a signed statement indicating the site is in compliance with the
permit to the best of the signer’s knowledge and belief after corrective actions have been
taken.
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Provided within Appendix E of this SWMP is an Example Inspection Log to aid in the record
keeping of BMP inspections and maintenance. Photographs, field notebooks, drawings, and maps
should be included by the SWMP Administrator when appropriate.
In addition to the Inspection Log, records should be kept documenting:
· BMP maintenance and operation
· Stormwater contamination
· Contacts with suppliers
· Notes on the need for and performance of preventive maintenance and other repairs
· Implementation of specific items in the SWMP
· Training events (given or attended)
· Events involving materials handling and storage
· Contacts with regulatory agencies and personnel
· Notes of employee activities, contact, notifications, etc.
Records of spills, leaks, or overflows that result in the discharge of pollutants must be documented
and maintained. A record of other spills responded to, even if they do not result in a discharge of
pollutants, should be made. Information that should be recorded for all occurrences includes the
time and date, weather conditions, reasons for the spill, etc. Some spills may need to be reported
to authorities immediately. Specifically, a release of any chemical, oil, petroleum product, sewage,
etc., which may enter waters of the State of Colorado (which include surface water, groundwater,
and dry gullies or storm sewers leading to surface water) must be reported to the CDPHE.
Additionally, the “Dynamic Site Plan” is intended to be a “living” document where the SWMP
Administrator can handwrite the location of BMPs as they are installed to appropriately reflect the
current site conditions. Also on the “Dynamic Site Plan” is a “Table of Construction Sequence and
BMP Application/Removal” the SWMP Administrator can use to document when BMPs were
installed or removed in conjunction with construction activities. These items have been included as
an aid to the SWMP Administrator, and other methods of record keeping are at his or her
discretion.
This Stormwater Management Plan (both the text and map) is not a static document. It is a
dynamic device intended to be kept current and logged as construction occurs. It shall be
the responsibility of the SWMP Administrator and/or the permit holder (or applicant
thereof) to ensure the plan is properly maintained and followed. Diligent administration is
critical, including processing the Notice to Proceed and noting on the Stormwater
Management Plan the dates that various construction activities occur and respective BMPs
are installed and/or removed.
8.0 FINAL STABILIZATION AND LONG-TERM STORMWATER MANAGEMENT
8.1 FINAL VEGETATION AND STABILIZATION
Final stabilization of the site will be achieved by either leaving a gravel surface in place of the
existing asphalt roadway or by reseeding. If reseeding is to be used, all disturbed areas will be
seeded, crimped, and mulched within 24 hours of seeding per the FCDCM Chapter 2 Section
6.1.4.9.
`
22
Soil amendments such as compost, peat, aged manure, or other similar materials shall also be
utilized. Soil amendments shall be tilled into the soil to a minimum depth of 6” and should comply
with the requirements found in City Code Section 12-132 (also refer to Land Use Code 3.8.21).
According to CDOT, reseeding shall occur either in the spring or fall, dependent on completion
date. Spring seeding shall occur between spring thaw and May 15th, while Fall seeding occurs
between September 30th until the ground is consistently frozen. If Fall seeding occurs, appropriate
measures to prevent erosion shall be taken, consistent with the BMPs established in this report.
A native seed mix shall be installed per the Landscape plan seed mix and installation instructions. If
a seed mix is not specified, a Fort Collins approved seed mix shall be used. The Seed shall be drill
seeded to a depth as specified by the manufacturer.
Table 3 - Native Grass Seed Mix
Non-seed stabilization is expected to be completed soon after hardscape construction is complete.
Seeded areas will require more time to establish and may need to be irrigated to establish growth.
As defined by the Colorado Department of Public Health and Environment (CDPHE) in the General
Permit Application for Stormwater Discharges, “Final stabilization is reached when all soil
disturbing activities at the site have been completed, and uniform vegetative cover has been
established with a density of at least 70 percent of pre-disturbance levels or equivalent permanent,
physical erosion reduction methods have been employed.” Establishment of 70 percent is required
for a determination for project closure by the City of Fort Collins.
The timeline for completion of stabilization will largely be dictated by the season that the project
ends in. If the project is completed in the summer or fall, final stabilization will occur after the
seeding that occurs in the fall takes root and grows the following spring. If the project is
completed in the winter or spring, final stabilization will occur immediately following the spring
seeding and growing season.
8.2 LONG-TERM STORMWATER MANAGEMENT
The primary method of long-term stormwater management will be bio-retention basins. The bio-
retention basins will remove suspended sediment and pollutants from developed run-off before
entering drainage facilities downstream of the site.
`
23
After stabilization, before project closure, all sediment shall be removed from storm piping per
FCDCM Chapter 2 Section 6.1.4.9.
All disturbed areas will receive permanent paving or be vegetated per the Landscape Plan. Low
Impact Development (LID) treatment will provide significant water quality enhancement and will
serve the long-term stormwater management goals for this project.
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24
9.0 ADDITIONAL SWMP AND BMP RESOURCES
Mile High Flood District
Urban Storm Drainage Criteria Manual - Volume 3 “Best Management Practices”
Colorado Department of Transportation
Erosion Control and Stormwater Quality Guide
BMP Field Academy
EPA Menu of BMPs
Construction Site Storm Water Runoff Control
International Stormwater Best Management (BMP) Database
Rocky Mountain Education Center
Rocky Mountain Education Center
Red Rocks Community College, Lakewood
Keep It Clean Partnership
Boulder
10.0 REFERENCES
1. Drainage Report for The Landing at Lemay, Avant Civil Group, September 27, 2023 (ACG Project
No. 1791-003)
2. City of Fort Collins Landscape Design Guidelines for Stormwater and Detention Facilities,
November 5, 2009, BHA Design, Inc. with City of Fort Collins Utility Services.
3. Fort Collins Stormwater Criteria Manual, City of Fort Collins, Colorado, adopted December 2018,
and referenced in Section 26-500 (c) of the City of Fort Collins Municipal Code
4. Larimer County Urban Area Street Standards, Adopted January 2, 2001, Repealed and Reenacted,
Effective October 1, 2002, Repealed and Reenacted, Effective April 1, 2007, Repealed and
Reenacted, Effective August 1, 2021
5. Soil Resource Report for Larimer County Area, Colorado, Natural Resources Conservation Service,
United States Department of Agriculture.
6. Urban Storm Drainage Criteria Manual, Volumes 1-3, Mile High Flood Control District,
Wright-McLaughlin Engineers, Denver, Colorado, Revised January 2021.
`
APPENDIX A
SITE MAPS
`
APPENDIX B
EROSION CONTROL DETAILS
Extended Detention Basin (EDB) T-5
November 2015 Urban Drainage and Flood Control District EDB-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph EDB-1: This EDB includes a concrete trickle channel and a
micropool with a concrete bottom and grouted boulder sideslopes. The
vegetation growing in the sediment of the micropool adds to the natural look
of this facility and ties into the surrounding landscape.
Description
An extended detention basin (EDB) is a
sedimentation basin designed to detain
stormwater for many hours after storm
runoff ends. This BMP is similar to a
detention basin used for flood control,
however; the EDB uses a much smaller
outlet that extends the emptying time of
the more frequently occurring runoff
events to facilitate pollutant removal.
The EDB's 40-hour drain time for the
water quality capture volume (WQCV) is
recommended to remove a significant
portion of total suspended solids (TSS).
Soluble pollutant removal is enhanced by
providing a small wetland marsh or
"micropool" at the outlet to promote
biological uptake. The basins are
sometimes called "dry ponds" because
they are designed not to have a significant permanent pool of
water remaining between storm runoff events.
Site Selection
EDBs are well suited for watersheds with at least five impervious
acres up to approximately one square mile of watershed. Smaller
watersheds can result in an orifice size prone to clogging. Larger
watersheds and watersheds with baseflows can complicate the
design and reduce the level of treatment provided. EDBs are also
well suited where flood detention is incorporated into the same
basin. The depth of groundwater should be investigated.
Groundwater depth should be 2 or more feet below the bottom of
the basin in order to keep this area dry and maintainable.
Extended Detention Basin
Functions
LID/Volume Red. Somewhat
WQCV Capture Yes
WQCV+Flood Control Yes
Fact Sheet Includes
EURV Guidance Yes
Typical Effectiveness for Targeted
Pollutants3
Sediment/Solids Good
Nutrients Moderate
Total Metals Moderate
Bacteria Poor
Other Considerations
Life-cycle Costs4 Moderate
3 Based primarily on data from the
International Stormwater BMP Database
(www.bmpdatabase.org).
4 Based primarily on BMP-REALCOST
available at www.udfcd.org. Analysis based
on a single installation (not based on the
maximum recommended watershed
tributary to each BMP).
T-5 Extended Detention Basin (EDB)
EDB-2 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Benefits
The relatively simple design can
make EDBs less expensive to
construct than other BMPs,
especially for larger basins.
Maintenance requirements are
straightforward.
The facility can be designed for
multiple uses.
Limitations
Ponding time and depths may
generate safety concerns.
Best suited for tributary areas of
5 impervious acres or more.
EDBs are not recommended for
sites less than 2 impervious
acres.
Although ponds do not require
more total area compared to other
BMPs, they typically require a
relatively large continuous area.
EDBs providing combined water quality and flood control functions can serve multiple uses such as
playing fields or picnic areas. These uses are best located at higher elevation within the basin, above
the WQCV pool level.
Designing for Maintenance
Recommended maintenance practices for all BMPs are
provided in the BMP Maintenance chapter of this manual.
During design, the following should be considered to ensure
ease of maintenance over the long-term:
Always provide a micropool (see step 7).
Provide a design slope of at least 3% in the vegetated
bottom of the basin (either toward the trickle channel or
toward the micropool). This will help maintain the
appearance of the turf grass in the bottom of the basin and
reduce the possibility of saturated areas that may produce
unwanted species of vegetation and mosquito breeding
conditions. Verify slopes during construction, prior to
vegetation.
Follow trash rack sizing recommendations to determine
the minimum area for the trash rack (see design step 9).
Provide adequate initial surcharge volume for frequent
inundation (see design step 3).
Provide stabilized access to the forebay, outlet, spillway,
and micropool for maintenance purposes.
Provide access to the well screen. The well screen
requires maintenance more often than any other EDB
component. Ensure that the screen can be reached from a
point outside of the micropool. When the well screen is
located inside the outlet structure, provide an access port
within the trash rack or use a sloped trash rack that consists of bearing bars (not horizontal) that create
openings no more than five inches clear.
Provide a hard-bottom forebay that allows for removal of sediment.
Where baseflows are anticipated, consider providing a flow-measuring device (e.g. weir or flume
with staff gage and rating curve) at the forebay to assist with future modifications of the water quality
plate. Typically, the baseflow will increase as the watershed develops. It is important that the water
quality plate continue to function, passing the baseflow while draining the WQCV over
approximately 40 hours. Measuring the actual baseflow can be helpful in determining if and when
the orifice place should be replaced.
Extended Detention Basin (EDB) T-5
November 2015 Urban Drainage and Flood Control District EDB-3
Urban Storm Drainage Criteria Manual Volume 3
Design Procedure and Criteria
The following steps outline the design procedure and criteria for an EDB and Figure EDB-3 shows a
typical configuration. UD-BMP, available at www.udfcd.org, is an Excel based workbook that can be
used to perform some of the below calculations and ensure conformance to these criteria. UD-Detention,
another workbook developed by UDFCD can be used to develop and route a storm hydrograph through an
EDB and design the outlet structure.
1. Basin Storage Volume: Provide a design volume equal to the WQCV or the EURV. This volume
begins at the lowest orifice in the outlet structure.
Determine the imperviousness of the watershed (or effective imperviousness where LID elements
are used upstream).
Find the required storage volume. Determine the required WQCV or EURV (watershed inches of
runoff) using Figure 3-2 located in Chapter 3 of this manual (for WQCV) or equations provided
in the Storage chapter of Volume 2 (for EURV).
Calculate the design volume as follows:
For WQCV: 𝑉= �WQCV 12 �𝐴 Equation EDB-1
For EURV: 𝑉= �EURV 12 �𝐴 Equation EDB-2
Where:
V = design volume (acre ft)
A = watershed area tributary to the extended detention basin (acres)
2. Basin Shape: Always maximize the distance between the inlet and the outlet. It is best to have a
basin length (measured along the flow path from inlet to outlet) to width ratio of at least 2:1. A
longer flow path from inlet to outlet will minimize short circuiting and improve reduction of TSS. To
achieve this ratio, it may be necessary to modify the inlet and outlet points through the use of pipes or
swales.
3. Basin Side Slopes: Basin side slopes should be stable and gentle to facilitate maintenance and
access. Slopes that are 4:1or flatter should be used to allow for conventional maintenance equipment
and for improved safety, maintenance, and aesthetics. Side slopes should be no steeper than 3:1. The
use of walls is highly discouraged due to maintenance constraints.
4. Inlet: Dissipate flow energy at concentrated points of inflow. This will limit erosion and promote
particle sedimentation. Inlets should be designed in accordance with UDFCD drop structure criteria
for inlets above the invert of the forebay, impact basin outlet details for at grade inlets, or other types
of energy dissipating structures.
T-5 Extended Detention Basin (EDB)
EDB-4 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
5. Forebay Design: The forebay provides an opportunity for larger particles to settle out in an area that
can be easily maintained. The length of the flow path through the forebay should be maximized, and
the slope minimized to encourage settling. The appropriate size of the forebay may be as much a
function of the level of development in the tributary area as it is a percentage of the WQCV. When
portions of the watershed may remain disturbed for an extended period of time, the forebay size will
need to be increased due to the potentially high sediment load. Refer to Table EDB-4 for a design
criteria summary. When using this table, the designer should consider increasing the size of the
forebay if the watershed is not fully developed.
The forebay outlet should be sized to release 2% of the undetained peak 100-year discharge. A soil
riprap berm with 3:1 sideslopes (or flatter) and a pipe outlet or a concrete wall with a notch outlet
should be constructed between the forebay and the main EDB. It is recommended that the berm/pipe
configuration be reserved for watersheds in excess of 20 impervious acres to accommodate the
minimum recommended pipe diameter of 8 inches. When using the berm/pipe configuration, round
up to the nearest standard pipe size and use a minimum diameter of 8 inches. The floor of the forebay
should be concrete or lined with grouted boulders to define sediment removal limits. With either
configuration, soil riprap should also be provided on the downstream side of the forebay berm or wall
if the downstream grade is lower than the top of the berm or wall. The forebay will overtop
frequently so this protection is necessary for erosion control. All soil riprap in the area of the forebay
should be seeded and erosion control fabric should be placed to retain the seed in this high flow area.
6. Trickle Channel: Convey low flows from the forebay to the micropool with a trickle channel. The
trickle channel should have a minimum flow capacity equal to the maximum release from the forebay
outlet.
Concrete Trickle Channels: A concrete trickle channel will help to establish the bottom of the
basin long-term and may also facilitate regular sediment removal. It can be a "V" shaped
concrete drain pan or a concrete channel with curbs. A flat-bottom channel facilitates
maintenance. A slope between 0.4% - 1% is recommended to encourage settling while reducing
the potential for low points within the pan.
Soft-bottom Trickle Channels: When designed and maintained properly, soft-bottom trickle
channels can allow for an attractive alternative to concrete. They can also improve water quality.
However, they are not appropriate for all sites. Be aware, maintenance of soft bottom trickle
channels requires mechanical removal of sediment and vegetation. Additionally, this option
provides mosquito habitat. For this reason, UDFCD recommends that they be considered on a
case-by-case basis and with the approval of the local jurisdiction. It is recommended that soft
bottom trickle channels be designed with a consistent longitudinal slope from forebay to
micropool and that they not meander. This geometry will allow for reconstruction of the original
design when sediment removal in the trickle channel is necessary. The trickle channel may also
be located along the toe of the slope if a straight channel is not desired. The recommended
minimum depth of a soft bottom trickle channel is 1.5 feet. This depth will help limit potential
wetland growth to the trickle channel, preserving the bottom of the basin.
Riprap and soil riprap lined trickle channels are not recommended due to past maintenance
experiences, where the riprap was inadvertently removed along with the sediment during
maintenance.
Extended Detention Basin (EDB) T-5
November 2015 Urban Drainage and Flood Control District EDB-5
Urban Storm Drainage Criteria Manual Volume 3
Basins with micropools
have fewer mosquitoes.
Micropools reduce shallow
wet areas where breeding is
most favorable.
7. Micropool and Outlet Structure: Locate the outlet structure in the embankment of the EDB and
provide a permanent micropool directly in front of the structure. Submerge the well screen to the
bottom of the micropool. This will reduce clogging of the well screen because it allows water to flow
though the well screen below the elevation of the lowest orifice even when the screen above the water
surface is plugged. This will prevent shallow ponding in
front of the structure, which provides a breeding ground for
mosquitoes (large shallow puddles tend to produce more
mosquitoes than a smaller, deeper permanent pond).
Micropool side slopes may be vertical walls or stabilized
slopes of 3:1 (horizontal:vertical). For watersheds with less
than 5 impervious acres, the micropool can be located
inside the outlet structure (refer to Figures OS-7 and OS-8
provided in Fact Sheet T-12). The micropool should be at
least 2.5 feet in depth with a minimum surface area of 10
square feet. The bottom should be concrete unless a
baseflow is present or anticipated or if groundwater is
anticipated. Riprap is not recommended because it
complicates maintenance operations.
Where possible, place the outlet in an inconspicuous
location as shown in Photo EDB-3. This urban EDB utilizes landscaped parking lot islands
connected by a series of culverts (shown in Photo EDB-4) to provide the required water quality and
flood control volumes.
The outlet should be designed to release the WQCV over a 40-hour period. Draining a volume of
water over a specified time can be done through an orifice plate as detailed in Fact Sheet T-12. Use
reservoir routing calculations as discussed in the Storage Chapter of Volume 2 to assist in the design.
Two workbooks tools have been developed by UDFCD for this purpose, UD-FSD and UD-Detention.
Both are available at www.udfcd.org. UD-FSD is recommended for a typical EDB full spectrum
detention design. UD-Detention uses the same methodology and can be used for a full spectrum
detention basin or a WQCV only design. It also allows for a wider range of outlet controls should the
user want to specify something beyond what is shown in Fact Sheet T-12.
Refer to BMP Fact Sheet T-12 for schematics pertaining to structure geometry, grates, trash racks,
orifice plate, and all other necessary components.
The outlet may have flared or parallel wing walls as shown in Figures EDB-1 and EDB-2,
respectively. Either configuration should be recessed into the embankment to minimize its profile.
Additionally, the trash rack should be sloped with the basin side-slopes.
T-5 Extended Detention Basin (EDB)
EDB-6 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Photograph EDB-2. The initial surcharge volume of this EDB
is contained within the boulders that surround the micropool.
8. Initial Surcharge Volume: Providing a
surcharge volume above the micropool
for frequently occurring runoff
minimizes standing water and sediment
deposition in the remainder of the basin.
This is critical to turf maintenance and
mosquito abatement in the basin bottom.
The initial surcharge volume is not
provided in the micropool nor does it
include the micropool volume. It is the
available storage volume that begins at
the water surface elevation of the
micropool and extends upward to a
grade break within the basin (typically
the invert of the trickle channel).
Photograph EDB-3. Although walls may complicate maintenance
access, this outlet structure is relatively hidden from public view.
This photo was taken shortly following a storm event.
Extended Detention Basin (EDB) T-5
November 2015 Urban Drainage and Flood Control District EDB-7
Urban Storm Drainage Criteria Manual Volume 3
The area of the initial surcharge
volume, when full, is typically
the same or slightly larger than
that of the micropool. The initial
surcharge volume should have a
depth of at least 4 inches. For
watersheds of at least 5
impervious acres, the initial
surcharge volume should also be
at least 0.3% of the WQCV. The
initial surcharge volume is
considered a part of the WQCV
and does not need to be provided
in addition to the WQCV. It is
recommended that this area be
shown on the grading plan or in a
profile for the EDB. When
baseflows are anticipated, it is
recommended that the initial
surcharge volume be increased.
See the inset on page EDB-9 for
additional guidelines for designing for baseflows.
9. Trash Rack: Provide a trash rack (or screen) of sufficient size at the outlet to provide hydraulic
capacity while the rack is partially clogged. Openings should be small enough to limit clogging of
the individual orifices. Size any overflow safety grate so it does not interfere with the hydraulic
capacity of the outlet pipe. See BMP Fact Sheet T-12 for detailed trash rack and safety grate design
guidance.
Photograph EDB-4. A series of landscape islands connected by culverts
provide water quality and flood control for this site.
T-5 Extended Detention Basin (EDB)
EDB-8 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Figure EDB-1. Flared wall outlet structure configuration. Graphic by Adia Davis.
Figure EDB-2. Parallel wall outlet structure configuration. Graphic by Adia Davis.
Extended Detention Basin (EDB) T-5
November 2015 Urban Drainage and Flood Control District EDB-9
Urban Storm Drainage Criteria Manual Volume 3
Designing for Baseflows
Baseflows should be anticipated for large
tributary areas and can be accommodated in
a variety of ways. Consider the following:
If water rights are available, consider
alternate BMPs such as a constructed
wetland pond or retention pond.
Anticipate future modifications to the
outlet structure. Following construction,
baseflows should be monitored
periodically. Intermittent flows can
become perennial and perennial flows
can increase over time. It may be
determined that outlet modifications are
necessary long after construction of the
BMP is complete.
Design foundation drains and other
groundwater drains to bypass the water
quality plate directing these drains to a
conveyance element downstream of the
EDB. This will reduce baseflows and
help preserve storage for the WQCV.
When the basin is fully developed and
an existing baseflow can be
approximated prior to design, the water
quality orifices should be increased to
drain the WQCV in 40 hours while also
draining the baseflow. This requires
reservoir routing using an inflow
hydrograph that includes the baseflow.
The UD-Detention workbook available
at www.udfcd.org may be used for this
purpose.
Increase the initial surcharge volume of
the pond to provide some flexibility
when baseflows are known or
anticipated. Baseflows are difficult to
approximate and will continue to
increase as the watershed develops.
Increasing the initial surcharge volume
will accommodate a broader range of
flows.
10. Overflow Embankment: Design the
embankment to withstand the 100-year storm at a
minimum. If the embankment falls under the
jurisdiction of the State Engineer's Office, it must
be designed to meet the requirements of the State
Engineer's Office. The overflow should be
located at a point where waters can best be
conveyed downstream. Slopes that are 4:1 or
flatter should be used to allow for conventional
maintenance equipment and for improved safety,
maintenance, and aesthetics. Side slopes should
be no steeper than 3:1 and should be planted with
turf forming grasses. Poorly compacted native
soils should be excavated and replaced.
Embankment soils should be compacted to 95% of
maximum dry density for ASTM D698 (Standard
Proctor) or 90% for ASTM D1557 (Modified
Proctor). Spillway structures and overflows
should be designed in accordance with the Storage
Chapter of Volume 2 as well as any local drainage
criteria. Buried soil riprap or reinforced turf mats
installed per manufacturer's recommendations can
provide an attractive and less expensive
alternative to concrete.
11. Vegetation: Vegetation provides erosion control
and sediment entrapment. Basin bottom, berms,
and side slopes should be planted with turf grass,
which is a general term for any grasses that will
form a turf or mat, as opposed to bunch grass
which will grow in clumplike fashion. Xeric
grasses with temporary irrigation are
recommended to reduce maintenance
requirements, including maintenance of the
irrigation system as well as frequency of mowing.
Where possible, place irrigation heads outside the
basin bottom because irrigation heads in an EDB
can become buried with sediment over time.
12. Access: Provide appropriate maintenance access
to the forebay and outlet works. For larger basins,
this means stabilized access for maintenance
vehicles. If stabilized access is not provided, the
maintenance plan should provide detail, including
recommended equipment, on how sediment and
trash will be removed from the outlet structure and
micropool. Some communities may require
T-5 Extended Detention Basin (EDB)
EDB-10 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
vehicle access to the bottom of the basin regardless of the size of the watershed. Grades should not
exceed 10% for haul road surfaces and 20% for skid-loader and backhoe access. Stabilized access
includes concrete, articulated concrete block, concrete grid pavement, or reinforced grass pavement.
The recommended cross slope is 2%.
Aesthetic Design
Since all land owners and managers wish to use land in the most efficient manner possible, it is important
that EDBs become part of a multi-use system. This encourages the design of EDBs as an aesthetic part of
a naturalized environment or to include passive and/or active open space. Within each scenario, the EDB
can begin to define itself as more than just a drainage facility. When this happens, the basin becomes a
public amenity. This combination of public amenity and drainage facility is of much greater value to a
landowner. Softened and varied slopes, interspersed irrigated fields, planting areas and wetlands can all
be part of an EDB.
The design should be aesthetic whether it is considered to be an architectural or naturalized basin.
Architectural basins incorporate design borrowed or reflective of the surrounding architecture or urban
forms. An architectural basin is intended to appear as part of the built environment, rather than hiding the
cues that identify it as a stormwater structure. A naturalized basin is designed to appear as though it is a
natural part of the landscape. This section provides suggestions for designing a naturalized basin. The
built environment, in contrast to the natural environment, does not typically contain the randomness of
form inherent in nature. Constructed slopes typically remain consistent, as do slope transitions. Even
dissipation structures are usually a hard form and have edges seldom seen in nature. If the EDB is to
appear as though it is a natural part of the landscape, it is important to minimize shapes that provide visual
cues indicating the presence of a drainage structure. For example, the side sides should be shaped more
naturally and with varying slopes for a naturalized basin.
Suggested Methods for a Naturalized Basin
Create a flowing form that looks like it was shaped by water.
Extend one side of the basin higher than the other. This may require a berm.
Shape the bottom of the basin differently than the top.
Slope of one side of the basin more mildly than the opposing side.
Vary slope transitions both at the top of the bank and at the toe.
Use a soft-surface trickle channel if appropriate and approved.
When using rock for energy dissipation, the rock should graduate away from the area of hard edge
into the surrounding landscape. Other non-functional matching rock should occur in other areas of
the basin to prevent the actual energy dissipation from appearing out of context.
Design ground cover to reflect the type of water regime expected for their location within the basin.
Extended Detention Basin (EDB) T-5
November 2015 Urban Drainage and Flood Control District EDB-11
Urban Storm Drainage Criteria Manual Volume 3
Additional Details are provided in BMP Fact Sheet T-12. This includes outlet structure
details including orifice plates and trash racks.
Figure EDB-3. Extended Detention Basin (EDB) Plan and Profile
T-5 Extended Detention Basin (EDB)
EDB-12 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Table EDB-4. EDB component criteria
On-Site EDBs
for
Watersheds
up to 1
Impervious
Acre1
EDBs with
Watersheds
between 1 and
2 Impervious
Acres1
EDBs with
Watersheds
up to 5
Impervious
Acres
EDBs with
Watersheds
over 5
Impervious
Acres
EDBs with
Watersheds
over 20
Impervious
Acres
Forebay
Release and
Configuration
EDBs should
not be used
for
watersheds
with less than
1 impervious
acre.
Release 2% of
the undetained
100-year peak
discharge by
way of a
wall/notch
configuration
Release 2% of
the undetained
100-year peak
discharge by
way of a
wall/notch
configuration
Release 2% of
the undetained
100-year peak
discharge by
way of a
wall/notch
configuration
Release 2% of
the undetained
100-year peak
discharge by
way of a
wall/notch or
berm/pipe2
configuration
Minimum
Forebay
Volume
1% of the
WQCV
2% of the
WQCV
3% of the
WQCV
3% of the
WQCV
Maximum
Forebay Depth 12 inches 18 inches 18 inches 30 inches
Trickle
Channel
Capacity
≥ the
maximum
possible
forebay outlet
capacity
≥ the
maximum
possible
forebay outlet
capacity
≥ the
maximum
possible
forebay outlet
capacity
≥ the
maximum
possible
forebay outlet
capacity
Micropool Area ≥ 10 ft2 Area ≥ 10 ft2 Area ≥ 10 ft2 Area ≥ 10 ft2
Initial
Surcharge
Volume
Depth ≥ 4
inches
Depth ≥ 4
inches
Depth ≥ 4 in.
Volume ≥
0.3% WQCV
Depth ≥ 4 in.
Volume ≥
0.3% WQCV
1 EDBs are not recommended for sites with less than 2 impervious acres. Consider a sand filter or rain
garden.
2 Round up to the first standard pipe size (minimum 8 inches).
Retention Pond T-7
November 2015 Urban Drainage and Flood Control District RP-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph RP-1. Retention ponds treat stormwater though
sedimentation and biological processes including uptake.
Description
A retention pond, sometimes called a
"wet pond," has a permanent pool of
water with capacity above the permanent
pool designed to capture and slowly
release the water quality capture volume
(WQCV) over 12 hours. The permanent
pool is replaced, in part, with stormwater
during each runoff event so stormwater
runoff mixes with the permanent pool
water. This allows for a reduced
residence time compared to that of the
extended detention basin (EDB). The 12-
hour drain time helps to both better
replicate pre-development flows for
frequent events and reduce the potential
for short circuiting treatment in smaller
ponds. Retention ponds can be very
effective in removing suspended solids, organic matter and metals through sedimentation, as well as
removing soluble pollutants like dissolved metals and nutrients through biological processes.
Site Selection
Retention ponds require groundwater or a dry-weather base flow
if the permanent pool elevation is to be maintained year-round.
They also require legal and physical use of water. In Colorado,
the availability of this BMP can be limited due to water rights
issues.
The designer should consider the overall water budget to ensure
that the baseflow will exceed evaporation, evapotranspiration, and
seepage losses (unless the pond is lined). High exfiltration rates
can initially make it difficult to maintain a permanent pool in a
new pond, but the bottom can eventually seal with fine sediment
and become relatively impermeable over time. However, it is best
to seal the bottom and the sides of a permanent pool if the pool is
located on permeable soils and to leave the areas above the
permanent pool unsealed to promote infiltration of the stormwater
detained in the surcharge WQCV.
Retention
Functions
LID/Volume Red. Somewhat
WQCV Capture Yes
WQCV+Flood Control Yes
Fact Sheet Includes
EURV Guidance Yes
Typical Effectiveness for Targeted
Pollutants3
Sediment/Solids Very Good
Nutrients Moderate
Total Metals Moderate
Bacteria Moderate
Other Considerations
Life-cycle Costs4 Moderate
3 Based primarily on data from the
International Stormwater BMP Database
(www.bmpdatabase.org).
4 Based primarily on BMP-REALCOST
available at www.udfcd.org. Analysis is
based on a single installation (not based on
the maximum recommended watershed
tributary to each BMP).
T-7 Retention Pond
RP-2 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Benefits
Creates wildlife and aquatic
habitat.
Provides recreation, aesthetics,
and open space opportunities.
Can increase adjacent property
values.
Cost-effective BMP for larger
tributary watersheds.
Limitations
Safety concerns associated with
open water.
Requires both physical supply of
water and a legal availability (in
Colorado) to impound water.
Sediment, floating litter, and
algae blooms can be difficult to
remove or control.
Ponds can attract water fowl
which can add to the nutrients
and bacteria leaving the pond.
Ponds increase water
temperature.
Studies show that retention ponds can cause an increase in
temperature from influent to effluent. Retention ponds are
discouraged upstream of receiving waters that are sensitive to
increases in temperature (e.g., fish spawning or hatchery
areas).
Use caution when placing this BMP in a basin where
development will not be completed for an extended period, or
where the potential for a chemical spill is higher than typical.
When these conditions exists, it is critical to provide adequate
containment and/or pretreatment of flows. In developing
watersheds, frequent maintenance of the forebay may be
necessary.
Designing for Maintenance
Recommended ongoing maintenance practices for all BMPs
are provided in Chapter 6 of this manual. During design, the
following should be considered to ensure ease of
maintenance over the long-term.
Provide pretreatment upstream of the permanent pool.
Provide maintenance access to the outlet structure as well
as the forebay.
Exceed the minimum criterion for the permanent pool
volume. Greater depth will help deter algae growth by
reducing temperature and the area of the pond bottom
that receives sunlight.
Design Procedure and Criteria
The following steps outline the retention pond design
procedure and criteria and Figure RP-1 shows a typical
configuration. UD-BMP, available at www.udfcd.org, is an Excel based workbook that can be used to
perform some of the below calculations and ensure conformance to these criteria. UD-Detention, another
workbook developed by UDFCD can be used to develop and route a storm hydrograph through a
retention pond and design the outlet structure.
1. Baseflow: Unless the permanent pool is establish by groundwater, a perennial baseflow that exceeds
losses must be physically and legally available. Net influx calculations should be conservative to
account for significant annual variations in hydrologic conditions. Low inflow in relation to the pond
volume can result in poor water quality. Losses include evaporation, evapotranspiration, and seepage.
Evaporation can be estimated from existing local studies or from the National Weather Service
(NWS) Climate Prediction website. Data collected from Chatfield Reservoir from 1990 to 1997 show
an average annual evaporation of 37 inches, while the NWS shows approximately 40 inches of
evaporation per year in the Denver metropolitan area. Potential evapotranspiration (which occurs
Retention Pond T-7
November 2015 Urban Drainage and Flood Control District RP-3
Urban Storm Drainage Criteria Manual Volume 3
when water supply to both plant and soil surface is unlimited) is approximately equal to the
evaporation from a large, free-water surface such as a lake (Bedient and Huber, 1992). When
retention ponds are placed above the groundwater elevation, a pond liner is recommended unless
evaluation by a geotechnical engineer determines this to be unnecessary.
2. Surcharge Volume: Provide a surcharge volume based on a 12-hour drain time.
Determine the imperviousness of the watershed (or effective imperviousness where LID elements
are used upstream).
Find the required storage volume. Determine the required WQCV or EURV (watershed inches of
runoff) using Figure 3-2 located in Chapter 3 of this manual (for WQCV) or equations provided
in the Storage chapter of Volume 2 (for EURV).
Calculate the design volume (surcharge volume above the permanent pool) as follows:
For WQCV: 𝑉 = �WQCV 12 �𝐴 Equation RP-1
For EURV: 𝑉= �EURV 12 �𝐴 Equation RP-2
Where:
V = design volume (acre ft)
A = tributary catchment drainage area (acres)
3. Basin Shape: Always maximize the distance between the inlet and the outlet. A basin length to
width ratio between 2:1 and 3:1 is recommended to avoid short-circuiting. It may be necessary to
modify the inlet and outlet locations through the use of pipes, swales, or channels to accomplish this.
4. Permanent Pool: The permanent pool provides stormwater quality enhancement between storm
runoff events through biochemical processes and continuing sedimentation.
Volume of the permanent pool: 𝑉𝑝≥ 1.2 �WQCV 12 �𝐴 Equation RP-3
Where:
V p = permanent pool volume (acre ft)
A = tributary catchment drainage area (acres)
T-7 Retention Pond
RP-4 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Depth Zones: The permanent pool should have two zones:
o Safety Wetland Bench: This area should be located along the perimeter of the pond, 6 to
12 inches deep and a minimum of 4 feet wide. Aquatic plant growth along the perimeter of
the permanent pool can help strain surface flow into the pond, protect the banks by stabilizing
the soil at the edge of the pond, and provide biological uptake. The safety wetland bench is
also constructed as a safety precaution. It provides a shallow area that allows people or
animals who inadvertently enter the open water to gain footing to get out of the pond.
o Open Water Zone: The remaining pond area should be open, providing a volume to promote
sedimentation and nutrient uptake by phytoplankton. To avoid anoxic conditions, the
maximum depth in the pool should not exceed 12 feet.
5. Side Slopes: Side slopes should be stable and sufficiently gentle to limit rill erosion and to facilitate
maintenance. Side slopes above the safety wetland bench should be no steeper than 4:1, preferably
flatter. The safety wetland bench should be relatively flat with the depth between 6 to 12 inches. The
side slope below this bench should be 3:1 (or flatter when access is required or when the surface
could be slippery). The steeper 3:1 slope below the safety wetland bench can be beneficial to
deterring algae growth as it will reduce the shallow area of the pond, thus reducing the amount of
sunlight that penetrates the pond bottom.
6. Inlet: Dissipate energy at the inlet to limit erosion and to diffuse the inflow plume. Inlets should be
designed in accordance with the Hydraulic Structures chapter of Volume 2. This chapter includes
design of impact basins and drop structures.
7. Forebay: Forebays provide an opportunity for larger particles to settle out, which will reduce the
required frequency of sediment removal in the permanent pool. Install a solid driving surface on the
bottom and sides below the permanent water line to facilitate sediment removal. A soil riprap berm
should be constructed to contain the forebay opposite of the inlet. This should have a minimum top
width of 8 feet and side slopes no steeper than 4:1. The forebay volume within the permanent pool
should be sized for anticipated sediment loads from the watershed and should be at least 3% of the
WQCV. If the contributing basin is not fully developed, additional measures should be taken to
maintain a relatively clean forebay. This includes more frequent maintenance of the forebay and/or
providing and maintaining temporary erosion control.
8. Outlet: The outlet should be designed to release the WQCV over a 12-hour period. This can be done
through an orifice plate as detailed in BMP Fact Sheet T-12. Use reservoir routing calculations as
discussed in the Storage Chapter of Volume 2 to properly design the outlet. The UD-Detention tool,
available at www.udfcd.org, can be used for this purpose.
Refer to BMP Fact Sheet T-12 for schematics pertaining to structure geometry, grates, trash racks,
orifice plate, and all other necessary components.
9. Trash Rack: Provide a trash rack of sufficient size to prevent clogging of the primary water quality
outlet. Similar to the trash rack design for the extended detention basin, extend the water quality trash
rack into the permanent pool a minimum of 28 inches. The benefit of this is documented in Fact
Sheet T-5. BMP Fact Sheet T-12 provides additional guidance on trash rack design including sizing
based on the smallest dimension of the orifice.
Retention Pond T-7
November 2015 Urban Drainage and Flood Control District RP-5
Urban Storm Drainage Criteria Manual Volume 3
Providing a buffer of tall
native grasses around a
retention pond provides
treatment through
filtering (straining) and
helps discourage frequent
use of the pond by geese.
Photograph RP-2. This retention pond outlet structure is
both accessible and functional while not interfering with the
natural aesthetic.
10. Overflow Embankment: Design the embankment not to fail during the 100-year storm. If the
embankment falls under the jurisdiction of the State Engineer's Office, it should be designed to meet
the requirements of the State Engineer's Office. Embankment slopes should be no steeper than 4:1,
preferably flatter, and planted with turf grasses. Poorly compacted native soils should be excavated
and replaced. Embankment soils should be compacted to 95% of maximum dry density for ASTM
D698 (Standard Proctor) or 90% for ASTM D1557 (Modified Proctor). Spillway structures and
overflows should be designed in accordance with local drainage criteria and should consider the use
of stabilizing materials such as buried soil riprap or reinforced turf mats installed per manufacturer's
recommendations.
11. Maintenance Considerations: The design should include a means of draining the pond to permit
drying out of the pond when it has to be "mucked out" to restore volume lost due to sediment
deposition. A means to drain the pond or a portion of the pond by gravity is preferred but not always
practicable. Some level of pumping is typically required. Past versions of this manual included an
underdrain at the perimeter of the pond with a valved connection to the outlet structure for this
purpose. This remains an acceptable method for draining
the pond. Additional alternatives include providing a
drywell with a piped connection to the outlet structure or
to a downstream conveyance element or connecting a
valved pipe directly to the outlet structure. The pipe
should include a valve that will only be opened for
maintenance.
12. Vegetation: Vegetation provides erosion control and
enhances site stability. Berms and side-sloping areas
should be planted with native grasses or irrigated turf,
depending on the local setting and proposed uses for the
pond area. The safety wetland bench should be vegetated
with aquatic species. This vegetation around the
perimeter of an open water body can discourage frequent
use of the pond by geese.
13. Access: All weather stable access to the
bottom, forebay, and outlet works area
should be provided for maintenance vehicles.
Grades should not exceed 10% for haul road
surfaces and should not exceed 20% for skid-
loader and backhoe access. Provide a solid
driving surface such as gravel, concrete,
articulated concrete block, concrete grid
pavement, or reinforced grass pavement. The
recommended cross slope is 2%.
T-7 Retention Pond
RP-6 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Figure RP-1. Retention Pond Plan and Sections
Retention Pond T-7
November 2015 Urban Drainage and Flood Control District RP-7
Urban Storm Drainage Criteria Manual Volume 3
Photograph RP-3. (altered photo) When incorporating rock into a
structure, use other matching, functional rock to prevent the structure
from looking out of context. Photo courtesy of Design Concepts.
Aesthetic Design
Since all land owners and managers wish to use land in the most efficient manner possible, it is important
that retention basins become part of a multi-use system. This encourages the design of retention ponds as
an aesthetic part of a naturalized environment or to be expanded to include passive and/or active open
space. Within each scenario, the retention basin can begin to define itself as more than just a drainage
facility. When this happens, the basin becomes a public amenity. This combination of public amenity
and drainage facility is of much greater value to a landowner. Softened and varied slopes, interspersed
irrigated fields, planting areas and wetlands can all be part of a retention pond.
The design should be aesthetic whether it is considered to be an architectural or naturalized basin.
Architectural basins incorporate design borrowed or reflective of the surrounding architecture or urban
forms. An architectural basin is intended to appear as part of the built environment, rather than hiding the
cues that identify it as a stormwater structure. A naturalized basin is designed to appear as though it is a
natural part of the landscape. This section provides suggestions for designing a naturalized basin. The
built environment, in contrast to the natural environment, does not typically contain the randomness of
form inherent in nature. Constructed slopes typically remain consistent, as do slope transitions. Even
dissipation structures are usually a hard form and have edges seldom seen in nature. If the retention pond
is to appear as though it is a natural part of the landscape, it is important to minimize shapes that provide
visual cues indicating the presence of a drainage structure. For example, the pond sides in the area of the
surcharge volume should be shaped more naturally and with varying slopes for a naturalized pond. See
Figure RP-2 for an example.
Suggested Methods for Creating the Look of a Naturalized Pond:
Create a flowing overall form that looks like it was shaped by water. This includes the banks of the
retention pond, which should have an undulating outline rather than a straight line.
One side of the pond can be higher than
the other side. This may require a berm.
The shape of the permanent pool should
vary from the shape of the surcharge
volume.
The slopes on at least three sides of the
pond (above the permanent pool) should
be varied and gentle. To achieve this, one
or more sides of the basin may have to be
stabilized by a retaining structure, i.e.,
stacked boulders and walls.
Vary slope transitions.
T-7 Retention Pond
RP-8 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Photograph RP-6. Landscape elements such as
vegetation and stone highlight the irregularly-shaped
pond edge, making it appear more natural. Photo
courtesy of Design Concepts.
Photograph RP-4. (altered photo) Variations in slope and texture around
the pond are brought together by mass groupings of local stone boulders.
The boulders are placed intermittently around the pond in groups and
interspersed with plantings. Photo courtesy of Design Concepts. Note: A
minimum 4-foot vegetated buffer (littoral zone) is recommended to strain
surface flow into the pond, protect the banks by stabilizing the soil at the
edge of the pond, and provide biological uptake.
Photograph RP-5. A curving stream with
vegetated edges provides habitat for wildlife. Photo
courtesy of Design Concepts.
Any use of rock for energy
dissipation or for erosion control
should graduate away from the area
of hard edge into the surrounding
landscape. Other functional
matching rock should occur in other
areas of the pond to prevent the
energy dissipation structure from
appearing out of context. Photo RP-
3 serves as an example of this.
If concrete is required in the basin,
colored concrete matching the rocks
or other site features of the
surrounding landscape can be used
to prevent the structure from
appearing out of context. Colored
concrete, form liners and veneers for
construction walls are preferred for
outlet structures.
Adjust the vegetation to the different uses of the pond surrounding.
Ground cover should reflect the type of water regime expected for the location within the basin. For
example, riparian plants would be placed around the edge of the retention pond, groups of trees and
shrubs would be placed in more manicured areas that have no retention or detention function.
Retention Pond T-7
November 2015 Urban Drainage and Flood Control District RP-9
Urban Storm Drainage Criteria Manual Volume 3
Figure RP-2. Example of a Naturalized Retention Pond
References
Bedient, Philip B. and Wayne C. Huber. 1992. Hydrology and Floodplain Analysis (Second Edition).
Addison-Wesley Publishing Company.
United States Environmental Protection Agency (EPA). 1999. Storm Water Technology Fact Sheet: Wet
Detention Ponds.
Outlet Structures T-12
November 2015 Urban Drainage and Flood Control District OS-1
Urban Storm Drainage Criteria Manual Volume 3
Designing for Maintenance
Rather than using the minimum criteria, consider maximizing the width of the trash rack to the
geometry of the outlet. This will reduce clogging and frequency of maintenance. Reduced
clogging in EDB outlet structures will preserve the initial surcharge volume thus reducing
frequency of inundation in the bottom of the basin. This will benefit the grasses and reduce long-
term EDB maintenance requirements (including sediment removal in the grassed area) and may
reduce the life-cycle cost of the BMP.
Description
This section provides guidance and details
for outlet structures for the use primarily
with BMPs utilizing sedimentation, (i.e.,
extended detention basins, retention ponds
and constructed wetland ponds). The
information provided in this section
includes guidance for different size
watersheds as well as for incorporating full
spectrum detention as described in the
Storage chapter of Volume 2.
The details contained in this Fact Sheet are
intended to provide a starting point for
design. UDFCD recommends that design
details for outlet structures be specific for
each site with structural details drawn to
scale. The details provided in this Fact
Sheet are not intended to be used without
modification or additional detail.
Outlet Design
Large Watershed Considerations
UDFCD recommends that water quality treatment be provided close to the pollutant source. This is a
fundamental concept of Low Impact Development (LID). Although flood control facilities, including full
spectrum detention facilities, have been shown to be very effective for watersheds exceeding one square
mile, this is not the case for water quality facilities. One reason for this is that the baseflow associated
with a larger watershed will vary and can be difficult to estimate. The orifice plate should be designed to
pass the baseflow while detaining the water quality capture volume (WQCV) for approximately 40 hours.
When the baseflow is overestimated, the WQCV is not detained for the recommended time, passing
through without treatment. When the baseflow is underestimated, the elevation of the permanent pool
will be higher than designed, causing maintenance issues as well as reducing the volume available for
detention of the WQCV, which also allows for a portion of this volume to pass through without treatment.
For this reason, UDFCD recommends that facilities designed for both water quality and flood control be
limited, where possible, to watersheds without a baseflow. The maximum recommended watershed for
combined facilities is one square mile. Additional discussion on designing for baseflows is provided in
the EDB BMP Fact Sheet (T-5).
Photograph OS-1. Although each site is different, most
sedimentation BMPs have similar outlet structures. Each structure
should include a partially submerged orifice plate with a screen (or
grate) protecting the orifice plate from clogging, and an overflow
weir for flows exceeding the WQCV or excess urban runoff volume
(EURV), when full spectrum detention is used.
T-12 Outlet Structures
OS-2 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Orifice Plates, Trash Racks, and Safety Grates
An orifice plate is used to release the WQCV slowly over 40 hours. For full spectrum detention, the
orifice plate is extended to drain a larger volume, the EURV, over approximately 72 hours. The figures
and tables in this section provide recommendations for orifice configurations and trash rack type and size.
Guidance is provided for plates using both circular and rectangular orifices.
Orifice Sizing
Follow the design steps included in the BMP Fact
Sheet for the appropriate BMP. The UD-Detention
workbook, available at www.udfcd.org, can be
used to route flows and calculate the required
orifice sizes. UDFCD recommends a total of three
orifices to maximize the orifice size and avoid
clogging of the orifice plate. A detail showing the
recommended orifice configuration is provided in
Figure OS-4.
Trash Rack Sizing
Once the size of the orifice has been determined,
this information, along with the total orifice area in
the water quality plate, is used to determine the
total open area of the grate. See Figure OS-1 and
use the dashed line to size the trash rack. Include
the portion of the trash rack that is inundated by the
micropool in total open area of the grate.
Be aware, Figures OS-5, OS-6, OS-7, and OS-8
dimension the minimum width clear for the trash
rack frame. It is also important to provide adequate
width for attachment to the outlet structure (see
Photos OS-2 and OS-3). Also, consider
maximizing the width of the trash rack to the
geometry of the outlet. This will reduce clogging
and maintenance requirements associated with
cleaning the trash rack. This Fact Sheet also
includes recommendations for the thickness of the
steel water quality plate (see Table OS-2).
Photograph OS-2. This trash rack could not be properly
Photograph OS-3. Trash rack after repair.
Outlet Structures T-12
November 2015 Urban Drainage and Flood Control District OS-3
Urban Storm Drainage Criteria Manual Volume 3
Safety Grates
Safety grates are intended to keep people and animals from inadvertently entering a storm drain. They are
sometimes required even when debris entering a storm drain is not a concern. The grate on top of the
outlet drop box is considered a safety grate and should be designed accordingly. The danger associated
with outlet structures is the potential associated with pinning a person or animal to unexposed outlet pipe
or grate. See the Culverts and Bridges chapter of Volume 2 of this manual for design criteria related to
safety grates.
Figure OS-1. Trash Rack Sizing
At / Aot = 77e-0.124D
At / Aot = 38.5e-0.095D
1
10
100
0 4 8 12 16 20 24 28 32 36 40 44 48
Ra
t
i
o
o
f
T
o
t
a
l
G
r
a
t
e
O
p
e
n
A
r
e
a
t
o
T
o
t
a
l
O
u
t
l
e
t
A
r
e
a
A
t /
A
ot
Outlet Diameter or Minimum Dimension D (Inches)
Safety Grates
Trash Racks
D>24"
4
T-12 Outlet Structures
OS-4 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Outlet Geometry
Outlets for small watersheds will typically be
sized for maintenance operations while the
geometry of outlets for larger watersheds may be
determined based on the required size of the trash
rack. For all watershed sizes, the outlet should be
set back into the embankment of the pond to better
allow access to the structure. This also provides a
more attractive BMP. For larger watersheds, this
will require wing walls. Wing walls are frequently
cast-in-place concrete, although other materials,
such as grouted boulders, may be used where
appropriate. Consider safety, aesthetics, and
maintenance when selecting materials and
determining the geometry. A safety rail should be
included for vertical drops of 3 feet or more.
Depending on the location of the structure in
relation to pedestrian trails, safety rails may also
be required for lesser drops. Stepped grouted
boulders can be used to reduce the height of
vertical drops.
As shown in Figures EDB-1 and EDB-2 provided
in BMP Fact Sheet T-5, wing walls can be flared
or parallel. There are advantages to both
configurations. Parallel wing walls may be more
aesthetic; however, depending on the geometry of
the pond, may limit accessibility to the trash rack.
Flared wing walls can call attention to the
structure but provide better accessibility and
sometimes a vertical barrier from the micropool of
an EDB, which can increase safety of the
structure. Parallel walls can also be used with a
second trash rack that is secured flush with the top
of the wall as shown in Photo OS-4. This
eliminates the need for a safety rail and may
provide additional protection from clogging;
however, it creates a maintenance issue by
restricting access to the water quality screen. The
rack shown in Photo OS-4 was modified after
construction due to this problem.
Photograph OS-4. Maintenance access to the water quality
trash rack was compromised by the location of a secondary
trash rack on this outlet. This may have been included as a
safety rack or as additional protection from clogging. The
owner modified the structure for better access. A safety rail
would have been a better solution.
Photograph OS-5. Interruptions in the horizontal members
of this trash rack and the spacing of the vertical members
allow easier access to clean the water quality grate. A
raking tool can be used to scrape the water quality trash
rack.
Outlet Structures T-12
November 2015 Urban Drainage and Flood Control District OS-5
Urban Storm Drainage Criteria Manual Volume 3
Micropools within the Outlet Structure
The micropool of an EDB may be placed inside the structure when desired. This is becoming
increasingly common for smaller watersheds and near airfields where large bird populations can be
problematic. When designing this type of structure, consider maintenance of the water quality trash rack.
The secondary trash rack should be designed to allow maintenance of the water quality trash rack similar
to that shown in Photo OS-5. This concept can easily be incorporated into smaller outlet structures (see
Figures OS-7 and OS-8 for details).
Outlet Structure Details
A number of details are presented in this section to assist designers with detailing outlet structures. Table
OS-1 provides a list of details available at www.udfcd.org. These details are not intended to be used in
construction plans without proper modifications as indicated in this table.
Table OS-1. Summary of Outlet Structure Details and Use
Figure Detail Use of Detail
OS-2 Typical outlet structure for full spectrum
detention Conceptual.
OS-3
Typical outlet structure for WQCV
treatment and attenuation Conceptual.
OS-4 Orifice plate and trash rack detail and
notes
Outlet section. Modify per true structure geometry
and concrete reinforcement. Modify notes per
actual design.
OS-5 Typical outlet structure with well screen
trash rack
Outlet sections. Modify per true structure
geometry and concrete reinforcement. Add
additional sections and detailing as necessary.
Modify notes per actual design.
OS-6 Typical outlet structure with bar grate
trash rack
Outlet sections. Modify per true structure
geometry and concrete reinforcement. Add
additional sections and detailing as necessary.
Modify notes per actual design.
OS-7 Full spectrum detention outlet structure for
5-acre impervious area or less
Outlet profile and section. Modify per true EURV
elevation and concrete reinforcement. Add
additional sections and detailing as necessary.
OS-8 WQCV outlet structure for 5-acre
impervious area or less
Outlet sections. Modify per true WQCV elevation
and concrete reinforcement. Add additional
sections and detailing as necessary.
T-12 Outlet Structures
OS-6 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Figure OS-2. Typical outlet structure for full spectrum detention
Figure OS-3. Typical outlet structure for WQCV treatment and attenuation
Outlet Structures T-12
November 2015 Urban Drainage and Flood Control District OS-7
Urban Storm Drainage Criteria Manual Volume 3
Figure OS-4. Orifice plate and trash rack detail and notes
T-12 Outlet Structures
OS-8 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Table OS-2. Thickness of steel water quality plate
Outlet Structures T-12
November 2015 Urban Drainage and Flood Control District OS-9
Urban Storm Drainage Criteria Manual Volume 3
Figure OS-5. Typical outlet structure with well screen trash rack
T-12 Outlet Structures
OS-10 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Figure OS-6. Typical outlet structure with bar grate trash rack
Outlet Structures T-12
November 2015 Urban Drainage and Flood Control District OS-11
Urban Storm Drainage Criteria Manual Volume 3
Figure OS-7. Full spectrum detention outlet structure for 5-acre impervious area or less
T-12 Outlet Structures
OS-12 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Figure OS-8. WQCV outlet structure for 5-acre impervious area or less
Covering Outdoor Storage and Handling Areas S-1
November 2010 Urban Drainage and Flood Control District CS-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph CS-1. Covered truck loading dock helps reduce
exposure of materials to runoff.
Description
When raw materials, byproducts,
finished products, storage tanks, and
other materials are stored or handled
outdoors, stormwater runoff that comes
in contact with the materials can become
contaminated. Proactively covering
storage and handling areas can be an
effective source control for such areas.
Coverings can be permanent or
temporary and consist of tarp, plastic
sheeting, roofing, enclosed structures, or
other approaches that reduce exposure of
materials to rainfall, runoff, and wind.
Appropriate Uses
Covering is appropriate for areas where
solids (e.g., gravel, salt, compost, building materials) or liquids (e.g., oil, gas, tar) are stored, prepared, or
transferred. Consider covering the following areas:
Loading and Unloading: Loading and unloading operations usually take place outside on docks,
truck terminals, or outside storage or staging areas at industrial and commercial sites. Materials
spilled, leaked, or lost during loading and unloading may collect in the soil or other surfaces and be
carried away by runoff, or when the area is cleaned. In addition to spills to the ground surface,
rainfall may wash pollutants off machinery used to unload and load materials. Materials may be
spilled during transfer between storage facilities and truck or rail car during pumping of liquids,
pneumatic transfer of dry chemicals, mechanical transfer using conveyor systems, or transfers of
bags, boxes, drums, or other containers by forklift, trucks, or other material handling equipment.
Aboveground Tanks/Liquid Storage: Accidental releases of chemicals from above-ground liquid
storage tanks can contaminate stormwater with a variety of pollutants. Several common causes of
accidental releases from above-ground tanks include: external corrosion and structural failure,
problems due to improper installation, spills and overfills due to operator error, failure of piping
systems, and leaks or spills during pumping of liquids or gases between trucks or rail cars to a storage
facility.
Outside Manufacturing: Common outside manufacturing activities may include parts assembly,
rock grinding or crushing, metals painting or coating, grinding or sanding, degreasing, concrete
manufacturing, parts cleaning or operations that use hazardous materials. These activities can result
in dry deposition of dust, metal and wood shavings and liquid discharges of dripping or leaking fluids
from equipment or processes and other residuals being washed away in storm runoff. In addition to
the manufacturing process, outside storage of materials and waste products may occur in conjunction
with outside manufacturing.
Waste Management: Wastes spilled, leached, or lost from outdoor waste management areas or
outside manufacturing activities may accumulate in soils or on other surfaces and be carried away by
rainfall runoff. There is also the potential for liquid wastes from surface impoundments to overflow
to surface waters or soak the soil where they can be picked up by runoff. Possible stormwater
S-1 Covering Outdoor Storage and Handling Areas
CS-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
contaminants include toxic compounds, oil and grease, oxygen-demanding organics, paints and
solvents, heavy metals and high levels of suspended solids. Lack of coverage of waste receptacles
can result in rainwater seeping through the material and collecting contaminants or the material being
blown around the site and into the stormwater collection system. Typical contaminant sources
include: landfills, waste piles, wastewater and solid waste treatment and disposal, land application
sites, dumpsters, or unlabeled drums.
Outside Storage of Materials: Raw materials, intermediate products, byproducts, process residuals,
finished products, containers, and materials storage areas can be sources of pollutants such as metals,
oils and grease, sediment and other contaminants. Pollutant transport can occur when solid materials
wash off or dissolve into water, or when spills or leaks occur.
Salt Storage: Salt left exposed to rain or snow may migrate to the storm sewer or contaminate soils.
Salt spilled or blown onto the ground during loading or unloading will dissolve in stormwater runoff.
Stormwater contaminated with salt in high concentrations can be harmful to vegetation, aquatic life
and groundwater quality. Typical contaminant sources include salt stored outside in piles or bags, salt
loading and unloading areas, and salt/sand storage piles used for deicing operations.
Practice Guidelines
Where practical, conduct operations indoors. Where impractical, select an appropriate temporary or
permanent covering to reduce exposure of materials to rainfall and runoff.
The type of covering selected depends on a variety of factors such as the type and size of activity
being conducted and materials involved. Types of cover range from relatively inexpensive tarps and
plastic sheeting to overhead structures or fully enclosed buildings equipped with ventilation, lighting,
etc.
Covering practices should be combined with Good Housekeeping BMPs to be most effective. Spill
containment berms are also often needed at industrial sites.
Measures such as tarps and plastic sheets typically require more frequent inspection and maintenance
than constructed facilities.
Spill Prevention, Containment and Control S-2
November 2010 Urban Drainage and Flood Control District SPCC-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SPCC-1. Use of secondary containment around supplies
stored outside helps to reduce the likelihood of spill and leaks reaching
the storm sewer system in runoff. Photo courtesy of Tom Gore.
Also See These BMP Fact Sheets
Covering Storage/Handling Areas
Good Housekeeping
Vehicle Fueling, Maintenance,
Washing & Storage
Preventative Maintenance
Description
Spills and leaks of solid and liquid
materials processed, handled or stored
outdoors can be a significant source of
stormwater pollutants. Spilled
substances can reach receiving waters
when runoff washes these materials
from impervious surfaces or when
spills directly enter the storm sewer
system during dry weather conditions.
Effective spill control includes both
spill prevention and spill response
measures and depends on proper
employee training for spill response
measures and may also include structural
spill containment, particularly at
industrial locations. Structural spill containment measures typically include temporary or permanent
curbs or berms that surround a potential spill site. Berms may be constructed of concrete, earthen
material, metal, synthetic liners, or other material that will safely contain the spill. Spill control devices
may also include valves, slide gates, or other devices that can control and contain spilled material before
it reaches the storm sewer system or receiving waters.
Appropriate Uses
Implement spill prevention, containment and control measures at municipal, commercial and industrial
facilities in areas where materials may be spilled in quantities that may adversely impact receiving waters
when discharged directly or through the storm sewer system. Check local, state, and/or federal
regulations to determine when spill containment and control measures are required by law. Spill
Prevention, Control and Countermeasures Plans may be required for certain facilities handling oil and
hazardous substances sunder Section 311(j)(1)(C) of the federal Clean Water Act.
Practice Guidelines
Spill Prevention Measures
Train employees on potential sources of pollution on-site
and provide clear, common-sense spill prevention
practices. Require that these practices be strictly followed.
Identify equipment that may be exposed to stormwater,
pollutants that may be generated and possible sources of
leaks or discharges.
Perform regular inspection and preventative maintenance of equipment to ensure proper operation
and to check for leaks or evidence of discharge (stains). Provide clear procedures to ensure that
needed repairs are completed and provide temporary leak containment until such repairs can be
implemented.
S-2 Spill Prevention, Containment and Control
SPCC-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Drain or replace motor oil and other automotive fluids in a designated area away from storm sewer
inlets. Collect spent fluids and recycle or dispose of properly. Never dispose of these fluids in the
storm sewer or sanitary sewer.
In fueling areas, clean up spills with dry methods (absorbents) and use damp cloths on gas pumps and
damp mops on paved surfaces. Never use a hose to “wash down” a fuel spill.
Where practical, reduce stormwater contact with equipment and materials by implementing indoor or
covered storage, implementing stormwater run-on control measures and following good housekeeping
practices.
Identification of Spill Areas
Identify potential spill areas, potential spill volumes, material types, frequency of material use, and
drainage paths from spill areas with relation to storm sewer inlets, adjacent waterbodies, structural BMPs,
and containment structures. Use this information to determine the types of spill prevention and control
measures needed specific to the site conditions. Examples of potential spill locations include:
Loading and unloading areas
Outdoor storage areas
Outdoor manufacturing or processing activities
Waste disposal/storage areas
Areas that generate significant dust or particulates (that may be subsequently deposited on the
ground)
Salt piles
Areas prone to spills based on past experience at the site
Locations where other routine maintenance activities occur such as equipment maintenance and
cleaning, pesticide/fertilizer application, etc.
Additionally, areas where smaller leaks may occur such as parking should also have basic spill cleanup
procedures.
Material Handling Procedures
From a water quality perspective, the primary principle behind effective material handling practices is to
minimize exposure to stormwater. This can be accomplished by storing the material indoors under
weather-resistant covering, elevating the material off the ground by using pallets, and diverting
stormwater around materials storage areas. Representative outdoor materials handling procedures
include:
Keep bulk solid materials such as raw materials, sand, gravel, topsoil, compost, concrete, packing
materials, metal products and other materials covered and protected from stormwater.
When practical, store materials on impermeable surfaces.
Store hazardous materials according to federal, state, and local hazardous materials requirements.
Spill Prevention, Containment and Control S-2
November 2010 Urban Drainage and Flood Control District SPCC-3
Urban Storm Drainage Criteria Manual Volume 3
Adopt procedures that reduce the chance of spills or leaks during filling or transfer of materials.
Substitute less toxic or non-toxic materials for toxic materials.
Store containers that are easily punctured or damaged away from high traffic areas (i.e., adopt a
materials flow/plant layout plan).
Add waste-capture containers such as collection pans for lubricating fluids.
Store drums and containers with liquid materials on impermeable surfaces and provide secondary
containment where appropriate. Drums stored outdoors should be located on pallets to minimize
contact with runoff.
Spill Response Procedures and Equipment
Spill response procedures should be tailored to site-specific conditions and industry-specific regulatory
requirements. General spill response procedures include:
Containment and cleanup of spills should begin promptly after the spill is observed.
Sweep up small quantities of dry chemical or solids to reduce exposure to runoff. Shoveling may be
used for larger quantities of materials.
Absorbents should be readily accessible in fueling areas or other areas susceptible to spills.
Wipe up small spills with a shop rag, store shop rags in appropriate containers, dispose of rags
properly or use a professional industrial cleaning service.
Contain medium-sized spills with absorbents (e.g., kitty litter, sawdust) and use inflatable berms or
absorbent “snakes” as temporary booms for the spill. Store and dispose of absorbents properly.
Wet/dry vacuums may also be used, but not for volatile fluids.
Develop procedures and locations for containing and storing leaking containers.
Install drip pans below minor equipment leaks and properly dispose of collected material until a
repair can be made.
For large spills, first contain the spill and plug storm drain inlets where the liquid may migrate off-
site, then clean up the spill.
Excavation of spill areas to removed contaminated material may be required where large liquid spills
occur on unpaved surfaces.
An inventory of cleanup materials should be maintained onsite and strategically located based on the
types and quantities of chemicals present.
Structural Spill Containment Measures
Two general approaches are often used when implementing spill containment measures. The first
approach is designed to contain the entire spill. The second approach uses curbing to route spilled
material to a collection basin. Both containment berming and curbing should be sized to safely contain or
convey to a collection basin a spill from the largest storage tank, rail car, tank truck, or other containment
device in the possible spill area. The spill containment area must have an impermeable surface (e.g.,
S-2 Spill Prevention, Containment and Control
SPCC-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Key Spill Notification Contacts in
Colorado
Colorado Department of Public
Health and Environment Toll-
Free 24-hour Environmental
Emergency Spill Reporting
Line: 1-877-518-5608
National Response Center: 1-
800-424-8802 (24-hour)
Local Emergency Planning
Committee (OEM): 303-273-
162
Division of Oil & Public Safety-
Storage Tanks: 303-318-8547
Oil and Gas Conservation
Commission: 303-894-2100 or
1-888-235-1101 (toll-free
spill/complaint line)
impermeable liner, asphalt or concrete) to prevent groundwater contamination. The containment system
must be designed to enable collection and removal of spilled material through a pump or vacuum trucks,
use of sorbent or gelling material, or other measures. Material removed from the spill area must be
disposed of or recycled according to local, state, and federal standards.
If the capacity of the containment berming or the collection basin is exceeded, supplemental spill control
measures should be available such as a portable containment device, sorbent materials, or gelling agents
that eventually solidify the material. Water that collects within containment areas due to rainfall or
snowmelt must be appropriately treated before release from the spill area.
Spill Plan Development
Many industries are required by federal law to have a Spill Prevention, Control and Countermeasures Plan
(SPCC) that meets specific regulatory criteria when certain types and quantities of materials are used or
processed at a site. These plans can be instrumental in developing a spill control plan for stormwater
management purposes. Even if an SPCC plan is not legally required at a site, a spill control plan for
stormwater management purposes may be necessary. Representative information appropriate for a spill
control plan, building on concepts previously introduced in this Fact Sheet, includes:
Site plan showing where materials are stored and handled, and where associated activities occur.
Notification procedures to be used in the event of an accident
Instructions for clean-up procedures.
A designated person with spill response and clean-up
authority.
Training of key personnel in plan and clean-up procedures.
Signs posted at critical locations providing a summary of
SPCC plan information, phone numbers, contacts,
equipment locations, etc.
Provisions requiring spills to be cleaned up, corrective
actions taken, or countermeasures implemented
immediately.
Provisions for absorbents to be made available for use in
fuel areas, and for containers to be available for used
absorbents.
Prohibition on washing absorbents into the storm drainage
system or into the sanitary sewer system via floor drains.
Provision for emergency spill containment and clean-up
kits in accessible and convenient locations. Kits should
contain the appropriate clean-up materials applicable to the
materials stored at the site.
Disposal of Household Waste S-3
November 2010 Urban Drainage and Flood Control District DHW-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph DHW-1. Placing storm
drain markers (or stenciling) at storm
sewer inlets is a public education tool that
can be used to educate citizens and
discourage improper disposal of
household waste in storm drains. Photo
courtesy of Nonpoint Source Colorado.
Description
Improperly disposed household wastes are a source of stormwater
pollution. These wastes can include household chemicals, pet
waste, yard waste, litter, automotive maintenance waste, and others.
These materials can be transported in stormwater when the
materials are dumped directly into the storm drains or when they
are spilled on impervious surfaces and washed into the storm sewer
system. Household wastes can contribute solids, nutrients, oxygen
demanding substances, toxic substances, and bacteria to receiving
waters. Improper disposal of household wastes on the ground
surface can also lead to groundwater contamination.
Proper disposal of household waste is dependent on behavioral
change, which can be encouraged through public education
programs and local ordinances that prohibit improper disposal of
household waste. Additionally, local governments can provide
appropriate facilities for proper disposal of waste.
This Fact Sheet focuses primarily on household waste. See the Good Housekeeping Fact Sheet for
additional information on waste management at commercial and industrial sites.
Appropriate Uses
Educational efforts related to proper disposal of household waste can be targeted to homeowners and
businesses through municipal programs, civic groups, and others. Local governments should consider
measures needed in the following general categories:
Household/Commercial Waste: Household waste includes materials discarded on the land surface
or into the stormwater system from residential and commercial areas. Wastes from commercial
businesses are generated by stores, restaurants, hotels, offices, and other non-manufacturing activities.
Household waste disposal objectives include containing and properly disposing of refuse (garbage),
reducing litter, and encouraging proper household toxic waste disposal through public education and
access to appropriate disposal facilities.
Litter: Most litter is biodegradable and can create an oxygen demand in water as it decomposes.
Examples of litter are paper products, used diapers, etc. Research by Keep America Beautiful, Inc.
(1990) has shown that people litter where litter has already accumulated. Also according to Keep
America Beautiful, Inc. (1987), pedestrians and motorists account for less than 25 percent of litter,
with the other sources being household waste, commercial and industrial waste, haulage vehicles,
loading docks, and construction sites. Reduction of litter through proper disposal can reduce its
accumulation on the urban landscape and its eventual entry into the stormwater system.
Pet Waste: Pet waste deposited on the ground can be transported by the storm drainage system to
receiving waters or by overland flow into waterways. Fecal matter potentially contains pathogenic
viruses and bacteria; it also creates an oxygen demand in water. The majority of improperly disposed
pet waste occurs in public areas, such as streets and parks. Pet waste ordinances are common in
municipalities; however, these are difficult to enforce, especially with limited municipal resources.
Education can help bring this problem to the public's attention, and can thereby reduce deposition of
pet waste on urban surfaces.
S-3 Disposal of Household Waste
DHW-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Composting
Composting is a natural method for
recycling organics such as yard trimmings
and food scraps, which comprise nearly a
quarter of municipal solids waste generated
(Keep America Beautiful 2010). Nearly
half of all U.S. states now ban yard waste
from landfills because it represents such a
large volume that can be productively
composted. Composted yard waste used as
mulch or soil amendment can provide
landscape water conservation benefits,
reduce the burden on landfills and is
protective of water quality.
Municipal Recycling Programs
Many communities throughout the country have implemented municipal recycling programs, rather
than relying on citizens to research and seek out recycling opportunities on their own. Curbside
recycling programs and municipal education campaigns can improve the success of recycling
programs. For more information on implementing a municipal recycling program, visit a variety of
U.S. Environmental Protection Agency websites such as:
http://www.epa.gov/epawaste/conserve/rrr/index.htm and
http://www.epa.gov/region4/waste/rcra/mgtoolkit/index.html or review well developed local programs
such as Denver Recycles.
Yard Waste: Yard waste includes limbs,
leaves and grass clippings that can
contribute nutrients, lawn chemicals, and
oxygen demand to receiving waters when
washed into storm sewers and waterways.
Public education efforts on the benefits of
composting and on proper disposal of yard
waste can help to reduce the volume of
yard waste entering the stormwater system
and receiving waters. Most yard waste
can be reused following composting, with
the exception of weeds and diseased plant
materials.
Used Oil and Automotive Fluids: Used
oil and automotive fluids including
antifreeze, brake fluid, transmission fluid,
grease, other lubricants, and petroleum-
based cleaning solvents are wastes
generated during automobile maintenance
by residential households and commercial
businesses. These can enter the storm
drainage system if poured directly into
storm inlets or from residual on concrete or asphalt exposed to precipitation. Improper disposal of
used oil and automotive fluids causes receiving waters to become contaminated with hydrocarbons
and residual metals that can be toxic to stream organisms. Used oil and other petroleum products can
be recycled and are accepted by many auto parts stores and repair shops. Public education on the
location of these centers, the benefits of recycling, prevention of fluid leaks, and the importance of
proper disposal for improving stormwater quality can reduce the amounts of oil and used automotive
fluids reaching receiving waters.
Toxic Wastes: Toxic wastes are generated in small quantities by residential households and
commercial businesses. Examples include paint, solvents, putties, cleaners, waxes, polishes, oil
products, aerosols, acids, caustics, pesticides, herbicides, and certain medicines or cosmetics. These
products and their containers should always be disposed of in accordance with the product label or
recycled, if appropriate. When such toxic substances are improperly disposed of by dumping on
impervious surfaces or into street gutters or storm inlets, stormwater can transport these materials to
receiving waters.
Disposal of Household Waste S-3
November 2010 Urban Drainage and Flood Control District DHW-3
Urban Storm Drainage Criteria Manual Volume 3
Photograph DHW-2. Check with state
and local water quality agencies for public
education materials such as this door
hanger developed by the Keep It Clean
Partnership that can be adopted for use in
your community. Photo courtesy of
Nonpoint Source Colorado.
Practice Guidelines
To reduce improper disposal of household waste, implement
public education efforts regarding how improper disposal of
wastes can degrade the quality of streams, rivers, lakes, and
wetlands. Local governments have many public education
options that can be tailored to fit local needs and budget
constraints the best. Within local governments, opportunities for
coordinated efforts among multiple departments may be
beneficial. For example, properly composting of yard waste can
provide a stormwater benefit when these materials are kept out of
the gutter, as well as a water conservation benefit when the
materials are reused as mulch and a solid waste management
benefit when these materials are kept out of landfills. Similarly,
public works and parks and recreation departments both benefit
from efforts related to pet waste disposal signage as well as
disposal facilities in parks.
Representative public education strategies may include:
Development, publication, and distribution of brochures.
Utility bill inserts, flyers, and handbills.
Newspaper articles and/or advertisements.
Development and distribution of educational videos.
Public workshops, field demonstrations, or presentations to
targeted civic organizations, youth organizations, etc.
Developing and offering school curricula or assembly
programs.
Creating posters, signs, and graphics for installation at parks,
school hallways, trails, etc.
Storm drain stenciling to discourage dumping of materials into
storm drains.
Signs, including graphics, on dumpsters and other locations
encouraging proper waste disposal.
Signs in parks and along streets on pet waste control and
ordinances.
Brochures and utility bill inserts on separation of wastes and recycling.
Advertising the locations of existing toxic disposal sites and waste recycling centers.
Advertising the locations of existing automobile fluids and used oil disposal sites.
S-3 Disposal of Household Waste
DHW-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Developing campaigns promoting voluntary neighborhood clean-up efforts.
Advertisements or notices of private locations accepting yard waste for composting.
Information on backyard or neighborhood composting and proper disposal of yard waste.
In addition to public education efforts, local governments can provide facilities that provide readily
available proper disposal opportunities. These practices include:
Establishing and maintaining household toxics disposal sites.
Annual or curbside collection of household toxics.
Pet waste disposal bags in public parks.
Providing waste containers in problem litter areas.
Requiring waste-haulage truck covers.
Seasonal or on-going collection programs for grass clippings, tree branches, and leaves with disposal
at composting or chipping facilities, paired with distribution programs for reuse of composted or
chipped materials.
With regard to household toxics, local governments should be aware that collection and disposal of
household wastes is expensive. Such programs require adequate training of operators, analysis of
unknown materials, safe transport and containers, extensive recordkeeping and awareness of regulatory
requirements (e.g., the federal Resource Conservation and Recovery Act) regarding disposal of such
materials.
Illicit Discharge Controls S-4
November 2010 Urban Drainage and Flood Control District IDC-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph IDC-1. Mapping and dry weather investigation of storm
sewer outfalls is an important tool in identifying and removing illicit
connections. Photo courtesy of WWE.
Description
Illicit discharges are non-stormwater
discharges into a storm drain system,
with some limited exceptions specified in
state and local discharge permits (e.g.,
fire fighting water, springs, and others).
Examples of illicit discharges include
illegal dumping (e.g., used oil),
accidental spills, failing septic systems,
improper disposal of sewage from
recreational activities such as boating or
camping, and improper plumbing of
sanitary discharges from residences and
commercial or industrial establishments
into the storm sewer system. A common
cause of illicit discharges is connection of
building or garage or floor drains to the storm
sewer system.
Control of illicit discharges involves a multi-faceted effort based on knowledge of the storm sewer
system, use of ordinances to prohibit illicit discharges, development of a coordinated plan to detect and
address illicit discharges, and a public education program to increase awareness of the problems caused
by illicit discharges.
Appropriate Uses
Illicit discharge control measures are usually implemented by municipal governments and metropolitan
districts, but may also be relevant to campus-scale developments or industries. Illicit discharge controls
are closely related to practices identified in the Good Housekeeping BMP Fact Sheet.
Practice Guidelines
Practice guidelines for illicit discharge controls are discussed in three general categories:
1. Public education to reduce illegal dumping and discharges,
2. Municipal actions to identify and remove illegal connections to the storm sewer system, and
3. Accidental spill response measures.
Public Education to Reduce Illegal Dumping and Discharges
Public education and awareness are the foundation for reducing illegal dumping and some types of illicit
discharges. For example, many citizens may not be aware that storm sewers drain to streams rather than
wastewater treatment plants or may not be aware of the environmental damage caused by discharging
soapy water, pet waste and other household wastes into the storm sewer system. Local governments
should select public awareness and education approaches most effective for their communities, which
may include a combination of some of these practices:
S-4 Illicit Discharge Controls
IDC-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Enactment of clearly written ordinances prohibiting illegal dumping and illicit connections. Many
local governments already have such ordinances; however, citizens are often unaware of these.
Publicity including news articles, door hangers, utility bill inserts, radio or TV advertisements,
website highlights and other measures can be used to increase awareness. Such efforts may be
particularly effective when connected to a specific water quality problem such as stream or lake
impairments due to bacteria and/or nutrients.
Storm drain stenciling involves placing a marker or using a stencil to paint a message on storm drains
to discourage dumping down the storm drain. These messages are a public education tool so that
citizens are aware that the materials that they dump down to the storm drain are discharged to a
stream, as opposed to a wastewater treatment plant.
Provide citizens with readily available contact information to report illegal dumping. Install a
"hotline" telephone number to handle calls from citizens reporting illegal dumping or accidental
spills.
Create brochures and other guidance for businesses related to illegal discharges to the storm drain.
Educational efforts should not only alert business owners that non-stormwater discharges are not
allowed, but also provide guidance on BMPs to implement. For example, power washing discharges
are process wastewater that may not be discharged to the storm sewer system. When power washing
is conducted, storm drain inlet protection, wet vacuuming, collection systems, and/or other
appropriate measures to prevent washwater from entering the storm drain system should be
implemented.
Illicit Connections
Eliminating illicit connections plumbed into the storm drain system involves two different components:
1. Identifying and removing existing illicit connections; and
2. Preventing new illicit connections.
Removing Existing Connections
Existing illicit connections of sanitary sewers to the storm drainage system in existing developments can
be identified by a systematic dry weather inspection of storm sewer outfalls following readily available
illicit discharge detection and elimination guidance available from EPA. Initial screening typically
involves mapping all storm sewer outfalls and conducting field inspections to identify suspect outfalls
based on odor, sewage-related residue (e.g., toilet paper), discoloration, dry weather flows, etc. Grab
samples of dry-weather discharges can be collected at suspect locations and analyzed for targeted water
quality constituents (e.g., E. coli, temperature, pH, surfactants). Where illicit connections are probable,
more advanced techniques can be used to isolate the likely source of the connection. Techniques such as
temperature probes (to track diurnal temperature changes indicative of shower use suggesting a sanitary
connection to a storm sewer), optical brightener screening (indicator of detergents), zinc chloride smoke
testing, fluorometric dye testing, television camera inspections and other approaches can be used as
follow-up measures. Once the illicit connection has been identified, the plumbing can be corrected and
proper connections to the sanitary sewer system implemented.
Illicit Discharge Controls S-4
November 2010 Urban Drainage and Flood Control District IDC-3
Urban Storm Drainage Criteria Manual Volume 3
Additional Illicit Discharge Detection and Elimination Guidance
The Center for Watershed Protection and Robert Pitt (2004) prepared Illicit Discharge
Detection and Elimination: A Guidance Manual for Program Development and
Technical Assessments under EPA funding to provide guidance to communities in
developing effective management programs and field guidance to reduce illicit
discharges. This manual provides detailed guidance and field forms that can be used
identify illicit connections.
Program elements to prevent illicit connections include:
Preventing Illicit Connections
Ensure that existing building and plumbing codes prohibit physical connections of non-stormwater
discharges to the storm drain system.
Have a program in place to review and approve any proposed connection into a storm sewer.
Require visual inspection of new developments or redevelopments during the construction phase to
ensure that proper plumbing connections are implemented. Train field inspectors and develop field
inspection procedures that prevent new illicit connections of sanitary sewer lines to storm sewers.
Accidental Spill Response
Although the storage, transport and disposal of hazardous and toxic substances is a highly regulated
activity under state and federal laws, accidents will inevitably occur, resulting in potential release of
chemicals and wastes into the storm sewer system. Most local police, fire, or other departments are
trained and equipped to respond to such spills. Local governments should work with response personnel
to ensure current mapping of storm drains and BMPs and review training procedures for spill response
and cleanup. Proper training combined with readily available knowledge of the storm sewer system and
appropriate spill control materials can result in more effective protection and blocking of the drainage
system during spill response.
Good Housekeeping S-5
November 2010 Urban Drainage and Flood Control District GH-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph GH-1. Use dry clean-up methods to remove spilled
materials. Photo courtesy of Colorado Nonpoint Source Program.
Description
Good housekeeping practices are designed
to maintain a clean and orderly work
environment. The most effective first
steps towards preventing pollution in
stormwater from work sites simply
involve using common sense to improve
the facility’s basic housekeeping methods.
Poor housekeeping practices result in
increased waste and potential for
stormwater contamination.
A clean and orderly work site reduces the
possibility of accidental spills caused by
mishandling of chemicals and equipment
and should reduce safety hazards to
personnel. A well-maintained material and
chemical storage area will reduce the
possibility of stormwater mixing with pollutants.
Some simple procedures a facility can use to promote good housekeeping include improved operation and
maintenance of machinery and processes, material storage practices, material inventory controls, routine
and regular clean-up schedules, maintaining well organized work areas, signage, and educational
programs for employees and the general public about all of these practices.
Appropriate Uses
Good housekeeping practices require education and training, typically targeted to industries and
businesses, municipal employees, as well as the general public.
Practice Guidelines
Good housekeeping practices include these general areas:
Operation and Maintenance
Material Storage
Material Inventory
Training and Participation.
Operation and Maintenance
Consider implementing the following practices:
Maintain dry and clean floors and ground surfaces by using brooms, shovels, vacuums or cleaning
machines, rather than wet clean-up methods.
Regularly collect and dispose of garbage and waste material.
S-5 Good Housekeeping
GH-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Routinely inspect equipment to ensure that it is functioning properly without leaking and conduct
preventative maintenance and needed repairs.
Train employees on proper clean up and spill response procedures.
Designate separate areas of the site for auto parking, vehicle refueling and routine maintenance.
Promptly clean up leaks, drips and other spills.
Cover and maintain dumpsters and waste receptacles. Add additional dumpsters or increase
frequency of waste collection if overflowing conditions reoccur.
Where outdoor painting and sanding occur, implement these practices:
o Conduct these activities in designated areas that provide adequate protection to prevent overspray
and uncontrolled emissions. All operations should be conducted on paved surfaces to facilitate
cleanup.
o Use portable containment as necessary for outside operations.
o Clean up and properly dispose of excess paint, paint chips, protective coatings, grit waste, etc.
Maintain vegetation on facility grounds in a manner that minimizes erosion. Follow the Landscape
Maintenance and Pesticide, Herbicide and Fertilizer Usage BMPs to ensure that minimum amounts of
chemicals needed for healthy vegetation are applied in a manner that minimizes transport of these
materials in runoff.
Material Storage Practices
Proper storage techniques include the following:
Provide adequate aisle space to facilitate material transfer and ease of access for inspection.
Store containers, drums, and bags away from direct traffic routes to reduce container damage
resulting in accidental spills.
Stack containers according to manufacturer’s instructions to avoid damaging the containers from
improper weight distribution. Also store materials in accordance with directions in Material Safety
Data Sheets (MSDSs).
Store containers on pallets or similar devices to prevent corrosion of containers that results from
containers coming in contact with moisture on the ground.
Store toxic or hazardous liquids within curbed areas or secondary containers.
Material Inventory Practices
An up-to-date materials inventory can keep material costs down by preventing overstocking, track how
materials are stored and handled onsite, and identify which materials and activities pose the most risk to
the environment. Assign responsibility of hazardous material inventory to individuals trained to handle
such materials. A material inventory should include these steps:
Identify all chemical substances present at work site. Perform a walk-through of the site, review
Good Housekeeping S-5
November 2010 Urban Drainage and Flood Control District GH-3
Urban Storm Drainage Criteria Manual Volume 3
purchase orders, list all chemical substances used and obtain Material Safety Data Sheets (MSDS) for
all chemicals.
Label all containers. Labels should provide name and type of substance, stock number, expiration
date, health hazards, handling suggestions, and first aid information. Much of, this information can
be found on an MSDS.
Clearly identify special handling, storage, use and disposal considerations for hazardous materials on
the material inventory.
Institute a shelf-life program to improve material tracking and inventory that can reduce the amount
of materials that are overstocked and ensure proper disposal of expired materials. Careful tracking of
materials ordered can result in more efficient materials use. Decisions on the amounts of hazardous
materials that are stored on site should include an evaluation of any emergency control systems that
are in place. All storage areas for hazardous materials should be designed to contain spills.
Training and Participation
Frequent and proper training in good housekeeping techniques reduces the likelihood that chemicals or
equipment will be mishandled. To promote good housekeeping, consider implementing these practices:
Discuss good housekeeping practices in training programs and meetings.
Publicize pollution prevention concepts through posters or signs.
Post bulletin boards with updated good housekeeping procedures, tips and reminders.
Preventative Maintenance S-6
November 2010 Urban Drainage and Flood Control District PM-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph PM-1. Preventative maintenance can reduce the
frequency and occurrence of leaked or spilled material that can be
transported in stormwater runoff.
Description
Preventative maintenance involves
proactive routine inspection and testing of
plant equipment and operational systems
to prevent leaks and spills. A preventative
maintenance program should also include
inspections of conveyance channels,
storm sewers, inlets, catch basins,
stormwater detention areas, and other
water quality treatment systems associated
with the site.
Appropriate Uses
This BMP is applicable to municipal,
industrial and commercial sites.
Preventative maintenance programs
typically incorporate practices identified in
the Good Housekeeping, Materials Storage
and Handling, Vehicle Fueling, Maintenance and Storage, and other source control BMPs. See the
Structural BMP Maintenance chapter for preventative maintenance for stormwater BMPs.
Practice Guidelines
Elements of a good preventative maintenance program should include:
Identification of equipment or systems, which may malfunction and cause spills, leaks, or other
situations that could lead to contamination of stormwater runoff. Typical equipment to inspect
includes pipes, pumps, storage tanks and bins, pressure vessels, pressure release valves, process and
material handling equipment.
Once equipment and areas to be inspected have been identified at the facility, establish schedules and
procedures for routine inspections and scheduling repairs.
Periodic testing of plant equipment for structural soundness is a key element in a preventative
maintenance program.
Promptly repair or replace defective equipment found during inspection and testing.
Keep spare parts for equipment that needs frequent repair.
Replace worn parts prior to failure.
Implement, maintain and regularly review a record keeping system for scheduling tests and
documenting inspections in the preventative maintenance program. Be sure to follow inspections
promptly with completion of needed repairs. Clearly record the problem and the specific actions
taken to correct the problem. Photos can be helpful components of such records. An annual review
of these records should be conducted to evaluate the overall effectiveness of the preventative
maintenance program. Refinements to the preventative maintenance procedures and tasking should
be implemented as necessary.
Vehicle Maintenance, Fueling and Storage S-7
November 2010 Urban Drainage and Flood Control District VFM-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph VF-1. Use drip pans to collect leaks from vehicles until
repairs can be completed. Photo courtesy of Tom Gore.
Description
Areas where vehicles are fueled,
maintained, and stored/parked can be
pollutant "hot spots" that can result in
hydrocarbons, trace metals, and other
pollutants being transported in stormwater
runoff. Proper fueling operations, storage
of automotive fluids and effective spill
cleanup procedures can help reduce
contamination of stormwater runoff from
vehicle maintenance and fueling facilities.
Fuel-related spills can occur due to
inattention during fueling or "topping off"
fuel tanks. Common activities at
commercial, industrial and municipal
maintenance shops include parts cleaning,
vehicle fluid replacement, and equipment
replacement and repair. Some of the
wastes generated at automobile maintenance facilities include solvents (degreasers, paint thinners, etc.),
antifreeze, brake fluid and brake pad dust, battery acid, motor oil, fuel, and lubricating grease. Fleet
storage areas and customer and employee parking can also be a source of vehicle-related contamination
from leaks, antifreeze spills, etc.
Appropriate Uses
These BMP guidelines are applicable to vehicle maintenance, fueling, fleet storage and parking facilities.
Be aware that washing vehicles and equipment outdoors or in areas where wash water flows onto the
ground can pollute stormwater. Vehicle wash water is considered process wastewater that should not be
discharged to the storm sewer system. Consult state and federal discharge permit requirements for proper
disposal of vehicle washwater, which is typically accomplished through discharge to the sanitary sewer
system.
Practice Guidelines 1
Perform maintenance activities inside or under cover. When repairs cannot be performed indoors, be
sure to use drip pans or absorbents.
Vehicle Maintenance
The most effective way to minimize wastes generated by automotive maintenance activities is to prevent
their production in the first place. Consider adopting these practices:
Keep equipment clean and free of excessive oil and grease buildup.
1 Guidelines adapted from the USEPA Menu of BMPs.
S-7 Vehicle Maintenance, Fueling and Storage
VFM-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Promptly cleanup spills using dry methods and properly dispose of waste. When water is required,
use as little as possible to clean spills, leaks, and drips.
Use a solvent collection service to collect spent solvent used for parts cleaning. Where practical, use
detergent-based, steam cleaning, or pressure-based cleaning systems instead of organic solvent
degreasers when practical. (Be aware that cleaning water discharged into the sanitary sewer may
require pre-treatment prior to discharge.)
When using liquids for cleaning, use a centralized station to ensure that solvents and residues stay in
one area. Locate drip pans and draining boards to direct solvents back into a solvent sink or holding
tank for reuse.
Store used oil for recycling in labeled tanks. Locate used oil tanks and drums away from storm
drains, flowing streams, and preferably indoors.
Use non-hazardous or less hazardous alternatives when practical. For example, replace chlorinated
organic solvents with non-chlorinated ones like kerosene or mineral spirits.
Properly recycle or dispose of grease, oil, antifreeze, brake fluid, cleaning solutions, hydraulic fluid,
batteries, transmission fluid, worn parts, filters, and rags.
Drain and crush oil filters before recycling or disposal.
Drain all fluids and remove batteries from salvage vehicles and equipment.
Closely monitor parked vehicles for leaks and place pans under any leaks to collect the fluids for
proper disposal or recycling.
Install berms or other measures to contain spills and prevent work surface runoff from entering storm
drains.
Develop and follow a spill prevention plan. This includes a variety of measures such as spill kits and
knowing where storm drains are located and how to protect them (e.g., drain mat, berm) when larger
spills occur. (See the Spill Prevention, Containment and Control BMP for more information.)
Conduct periodic employee training to reinforce proper disposal practices.
Promptly transfer used fluids to recycling drums or hazardous waste containers.
Store cracked batteries in leak-proof secondary containers.
Inspect outdoor storage areas regularly for drips, spills and improperly stored materials (unlabeled
containers, auto parts that might contain grease or fluids, etc.). This is particularly important for
parking areas for vehicles awaiting repair.
Structural stormwater BMPs in vehicle hotspot areas require routine cleanout of oil and grease,
sometimes monthly or more frequently. During periods of heavy rainfall, cleanout is required more
often to ensure that pollutants are not washed through the trap. Sediment removal is also required on
a regular basis to keep the BMP working efficiently.
Vehicle Maintenance, Fueling and Storage S-7
November 2010 Urban Drainage and Flood Control District VFM-3
Urban Storm Drainage Criteria Manual Volume 3
Vehicle Fueling
Designated fueling areas should be designed to prevent stormwater runoff and spills. For example,
fuel-dispensing areas should be paved with concrete or an equivalent impervious surface, with an
adequate slope to prevent ponding, and separated from the rest of the site by a grade break or berm
that prevents run-on of stormwater.
Fuel dispensing areas should be covered. The cover's minimum dimensions must be equal to or
greater than the area within the grade break or the fuel dispensing area so that the fueling area is
completely covered. It may be necessary to install and maintain an oil capture device in catch basins
that have the potential to receive runoff from the fueling area.
For facilities where equipment is being fueled with a mobile fuel truck, establish a designated fueling
area. Place temporary "caps" over nearby catch basins or manhole covers so that if a spill occurs, it is
prevented from entering the storm drain. A form of secondary containment should be used when
transferring fuel from the tank truck to the fuel tank. Storm drains in the vicinity should also be
covered. Install vapor recovery nozzles to help control drips, as well as reduce air pollution.
Keep spill response information and spill cleanup materials onsite and readily available.
Fuel-dispensing areas should be inspected regularly and repair promptly completed. Inspectors
should:
o Check for external corrosion and structural failure in aboveground tanks.
o Check for spills and overfills due to operator error.
o Check for failure of any piping systems.
o Check for leaks or spills during pumping of liquids or gases from a truck or rail car to a storage
facility or vice versa.
o Visually inspect new tank or container installations for loose fittings, poor welds, and improper or
poorly fitted gaskets.
o Inspect tank foundations, connections, coatings, tank walls, and piping systems. Look for
corrosion, leaks, cracks, scratches, and other physical damage that may weaken the tank or
container system.
Aboveground and belowground tanks should be tested periodically for integrity by a qualified
professional.
Dry cleanup methods should be employed when cleaning up fuel-dispensing areas. Such methods
include sweeping to remove litter and debris and using rags and absorbents for leaks and spills.
Water should not be used to wash these areas. During routine cleaning, use a damp cloth on the
pumps and a damp mop on the pavement, rather than spraying with a hose. Fuel dispensing nozzles
should be fitted with "hold-open latches" (automatic shutoff) except where prohibited by local fire
departments. Signs can be posted at the fuel dispenser or island warning vehicle owners/operators
against "topping off" vehicle fuel tanks.
Written procedures that describe these BMPs should be provided to employees who will be using
fueling systems.
Use of Pesticides, Herbicides and Fertilizers S-8
November 2010 Urban Drainage and Flood Control District PHF-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph PHF-1. Pesticide, fertilizer, and herbicide applications
should be applied in the minimum quantities necessary to achieve
specific landscaping objectives, while keeping chemicals out of storm
drain systems. Photo courtesy of WWE.
Description
Pesticides, herbicides, fertilizers, fuel and
other landscape maintenance chemicals
must be properly applied, stored, handled
and disposed of to prevent contamination
of surface water and groundwater. Misuse
of pesticides and herbicides can result in
adverse impacts to aquatic life, even at low
concentrations. Misuse of fertilizer can
result in increased algae growth in
waterbodies due to excessive phosphorus
and nitrogen loading.
Appropriate Uses
This BMP applies to both commercial and
municipal landscaping operations, as well as
to homeowners and homeowner associations. For commercial operations, the scale of chemical usage and
handling is greater; therefore, additional measures are often required under federal and state law.
Practice Guidelines 1
Public education regarding appropriate landscape chemical application and handling is an important
action that local governments can take to reduce the likelihood that landscape chemicals are washed into
storm drains and receiving waters through runoff. Local governments can make landscape care
information available on websites, in utility mailers, lawn care centers, and other locations. A variety of
professional organizations for lawn care professionals already exist and can be contacted for additional
information or partnered with for both public education and landscape professional educational efforts
and certification programs (See
www.ext.colostate.edu and www.greenco.org.).
General Guidelines for Pesticide, Herbicide, and Fertilizer Application
Apply fertilizers, pesticides, and other chemicals according to manufacturer's directions. The label is
the law for pesticide usage. Apply pesticides and herbicides only when needed and use in a manner
to minimize off-target effects. See the Landscape Management Fact Sheet for fertilizer application
guidelines.
Accurately diagnose the pest. Disease and insect symptoms can mimic each other in many plants. A
fungicide will not control an insect, and an insecticide will not control a disease.
Be aware that commercial chemical applicators must receive thorough training, licensure and proper
certification prior to chemical use. Consult Colorado Department of Agriculture (CDA) Regulations
for specific requirements.
1 These practice guidelines have been adapted from the GreenCO Best Management Practices for the
Conservation and Protection of Water Quality in Colorado: Moving Toward Sustainability (GreenCO
and WWE 2008). See that manual for additional detail and references.
S-8 Use of Pesticides, Herbicides and Fertilizers
PHF-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Integrated Pest Management (IPM)
Integrated pest management (IPM) (also known as Plant Health Care) is the practice of using targeted
biological, chemical, cultural, and physical measures to manage pests while minimizing or eliminating
the use of chemical pesticides. IPM measures benefit the landscape and help reduce the likelihood that
lawn chemicals will be washed into storm drainage systems in stormwater runoff. The pros and cons of
various tools should be weighed and used in an integrated manner to achieve pest control objectives in
a safe, effective, and cost-effective manner. Basic IPM practices that can be adopted include:
Consider spot treatments of pests rather than treating the entire area.
Consider pest occurrence and history when developing pest management strategies.
Time pesticide application to minimize host plant damage and maximize pest control.
Rotate annual garden plants to reduce the buildup of soil-borne pests. Clean up plant litter and
remove weeds before they go to seed. Remove infested plant residue from the garden in the fall so
that pests do not over-winter there.
Implement cultural controls such as proper plant selection, planting time, and planting method to
reduce susceptibility to insects, pests, and diseases, thereby reducing pesticide usage.
Implement mechanical and physical controls where practical as an alternative to chemical
application. Examples include a wide variety of practices such as "collars" around seedlings,
mulching, solar heating, syringing, handpicking, mowing, hoeing, and traps.
Use biological controls where appropriate to reduce pesticide usage. For example, introduce
natural enemies of pests such as lady beetles and green lacewings. (Note: pesticides may kill these
natural enemies.)
Consider applying environmentally friendly chemical alternatives such as insecticidal soaps,
horticultural oils, and other such measures when practical and effective and when mechanical
approaches are impractical.
Know characteristics of the application site, including soil type and depth to groundwater to avoid
migration of chemicals into groundwater.
Select pesticides and herbicides best suited to the characteristics of the target site and the particular
pest or weed. Half-life, solubility, and adsorption should be compared to site characteristics to
determine the safest chemical. Choose least toxic and less persistent sprays whenever possible based
on comparison of labels and associated material safety data sheets.
Employ application techniques that increase efficiency and allow the lowest effective application rate.
Carefully calibrate application equipment and follow all label instructions.
Recognize that it is not realistic for a landscape to be completely pest-free or weed-free. Consider
using Integrated Pest Management (IPM) strategies to minimize chemical usage.
Keep pesticide and fertilizer equipment properly calibrated according to the manufacturer's
instructions and in good repair. Recalibrate equipment periodically to compensate for wear in pumps,
nozzles and metering systems. Calibrate sprayers when new nozzles are installed.
All mixing and loading operations must occur on an impervious surface.
Use of Pesticides, Herbicides and Fertilizers S-8
November 2010 Urban Drainage and Flood Control District PHF-3
Urban Storm Drainage Criteria Manual Volume 3
Managing Mosquitoes in Stormwater Facilities
(Adapted from: Peairs and Cranshaw 2007)
The key to mosquito control is larval management. Larvae occur in specific areas and can be
controlled by modifying the habitat through drainage or insecticides applied to larval breeding sites.
Weekly mosquito inspections at stormwater facilities with targeted treatments are frequently less costly
and more effective than regular widespread application of insecticides. These inspections can be
performed by a mosquito control source and typically start in mid-May and extend to mid-September.
Mosquito control measures must be cost effective and environmentally sound. Consider alternatives
before application of conventional chemical insecticides.
Habitat Modification: Eliminating breeding sites, or habitat modification, is an effective and
long-term solution. Proper maintenance of stormwater BMPs to avoid shallow standing water is
important.
Natural Predators: Fish, dragonfly nymphs, and diving beetles are natural predators of mosquito
larvae; dragonflies, birds, and bats feed on adults. Consult the Colorado Division of Wildlife for
recommendations, restrictions and regulations regarding mosquito-eating fish.
Insecticides: Microbial insecticides such as the bacteria "Bti" (Bacillus thuringiensis israeliensis)
can be as effective as chemical insecticides. Bti is toxic only to mosquito and midge larvae. It is
not hazardous to non-target organisms but can reduce midge populations that serve as fish food.
"Soft" chemical insecticides, such as the insect growth regulator methoprene, are toxic only to
insects and other arthropods. They are similar to certain insect hormones and create imbalances in
the levels of hormones needed for proper mosquito growth and development. They do not directly
harm fish or other wildlife but can reduce the amount of available food.
Mosquito larvae also can be controlled by the application of larvicidal oils or chemical
insecticides to the water where they occur or are suspected to occur. Remember, several
alternatives to conventional chemical larvicides have been developed because of concerns about
applying chemicals to water that might be used for drinking or that contains fish and other aquatic
life.
If larval control fails, adult mosquito control may be necessary. Adult control generally is done with
insecticide applications using ground equipment or aircraft. For more information visit:
www.ext.colostate.edu/westnile/mosquito_mgt.html or www.ext.colostate.edu/westnile/faq.html.
Application Practices
Keep records of pesticide application and provide signage as required by law.
Do not apply pesticides or herbicides during high temperatures, windy conditions or immediately
prior to heavy rainfall or irrigation.
Treat for and control noxious weeds prior to installing the landscape using an herbicide targeted to the
weeds that are present and applied in accordance with the product label.
Be aware that some pesticide formulations are not compatible with other pesticides and combining
them may result in increased potency and phytotoxicity.
S-8 Use of Pesticides, Herbicides and Fertilizers
PHF-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Figure PHF-1. Example Combined Pesticide and Fertilizer Storage and Mixing Area. Figure courtesy of
Designing Facilities for Pesticides and Fertilizer Containment, Midwest Planning Service, Agricultural
Engineering, Iowa State University 1991.
Maintain a buffer zone around wells or surface water where pesticides are not applied. Consult local
regulations and landscape ordinances, as well as the product label, for distances, which may vary
depending on the type of chemical and the sensitivity of the waterbody. The purpose of this practice
is to keep pesticides and herbicides out of surface waterbodies.
Storage Practices
Storage areas should be secure and covered, preventing exposure to rain and unauthorized access.
Commercial and municipal facilities should provide basic safety equipment such as fire extinguishers,
warning signs (e.g., "no smoking"), adequate light and ventilation, and spill clean-up materials should
be present. Floors and shelves should be non-porous (e.g., metal, concrete) to prevent sorption of
chemicals. If possible, temperature control should be provided to avoid excessive heat or cold.
Storage areas should be kept clear of combustible material and debris.
Commercial operations handling large quantities of pesticides and fertilizers should consult the
Colorado Department of Agriculture for storage and handling requirements. Commercial greenhouses
and nurseries that are storing recycled water laden with fertilizer may need to provide secondary
containment to contain the water in the event of a tank rupture or leak.
Store chemicals in their original containers, tightly closed, with labels intact. Also inspect them
regularly for leaks. Store nitrate-based and other oxidizing fertilizers separately from solvents, fuels,
and pesticides to reduce fire risk. Follow the general principle of storing like chemicals together.
Dry chemicals should be stored above liquids and on pallets to ensure that they do not get wet.
Locate chemical storage and maintenance areas, as well as vehicle refueling and maintenance areas,
away from wells and surface waterbodies in accordance with local regulations, typically at least 50 to
100 feet away.
Use of Pesticides, Herbicides and Fertilizers S-8
November 2010 Urban Drainage and Flood Control District PHF-5
Urban Storm Drainage Criteria Manual Volume 3
For More Information on Legal Requirements
Many federal and state regulations address pesticide, herbicide, and other chemical usage. These
sources should be consulted for the most current legal requirements related to chemical handling,
storage, application, disposal, and reporting of chemical spills. Examples include the federal
Insecticide, Fungicide and Rodenticide Act (FIFRA), the Superfund Amendments and
Reauthorization Act (SARA), the Emergency Planning and Community-Right-to-Know Act
(EPCRA), and Occupational Safety and Health Administration (OSHA) requirements, particularly
the Hazard Communication Standard. Colorado-related regulations include the Colorado Pesticide
Applicator's Act, and the Colorado Water Quality Control Act (25-8-601 and 25-8-606), Senate Bill
90-126, and The Agricultural Chemicals and Groundwater Protection Act, which identifies special
requirements for facilities handling more than 3,000 pounds (or 500 gallons) of bulk-formulated
pesticides.
Make available all Material Safety Data Sheets (MSDSs) in a readily accessible area. A list of all
hazardous chemicals in the work place must be completed to ensure that all MSDSs are readily
available.
Do not store large quantities of pesticides for long periods of time. Adopt the "first in, first out"
principle, using the oldest products first to ensure that the shelf life does not expire. Buy smaller
quantities of pesticides and fertilizers, thereby reducing storage issues.
Spills and Disposal
Never pour lawn and garden chemicals or rinse water down storm drains (or sanitary drains) and keep
chemicals off impervious surfaces (e.g., streets, gutters) during application.
Follow label directions for disposal. This typically involves triple-rinsing empty containers,
puncturing and crushing. All visible chemicals should be cleaned from the container prior to
disposal. Use local recycling or hazardous waste collection centers to dispose of unused chemicals.
Properly manage chemical spills by cleaning them up as soon as possible, controlling actively spilling
or leaking materials, containing the spilled material (e.g., with absorbents, sand), collecting the spilled
material, storing or disposing of the spilled material, and following relevant spill reporting
requirements. "Washing down" a spill with water is not an appropriate cleanup approach.
Commercial operations should be aware of and comply with basic spill reporting requirements
required by law, and keep chemical spill cleanup equipment, personal protective equipment and
emergency phone numbers available when handling chemicals and their containers.
Landscape Maintenance S-9
November 2010 Urban Drainage and Flood Control District LM-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph LM-1. Over-irrigation and overspray can wash fertilizers
and lawn chemicals into the storm drain system. These flows can
comingle with storm runoff and cause nuisance flow conditions in
stormwater BMPs. Photo courtesy of the City of Westminster.
Description
Proper landscape maintenance, including
maintenance of vegetated stormwater
BMPs, is important to reduce nutrient
and chemical loading to the storm drain
system, reduce nuisance flows and
standing water in stormwater BMPs, and
maintain healthy vegetation that helps
minimize erosion. Additionally, when
landscapes and vegetated BMPs are over-
irrigated, the ground remains saturated
and capacity to infiltrate runoff is
reduced.
Appropriate Uses
Appropriate lawn care practices are
applicable to residential, commercial,
municipal, and some industrial operations.
Practice Guidelines 1
Keep lawn clippings and debris out of gutters. When blowing walkways or mowing lawns, direct
equipment so that the clippings blow back onto the lawn rather than into the street, or collect
clippings blown onto the street and properly dispose of them.
Practice guidelines for a healthy lawn that reduces pollution during both wet and dry weather conditions
include a combination of practices such as mowing, aeration, fertilization, and irrigation. Also, see the
Pesticide, Herbicide, and Fertilizer Usage BMP for information on proper use of these chemicals and
Integrated Pest Management (IPM) strategies.
Lawn Mowing and Grass Clipping Waste Disposal
Mulch-mowing turfgrass at a height of 2.5 to 3 inches helps turfgrass develop deeper root systems.
No more than one-third of the grass blade should be removed in a single mowing. Mulched grass
clippings can return roughly 25 to 30% of the needed nitrogen that grass requires to be healthy,
thereby reducing fertilizer requirements. Avoid throwing grass clippings onto streets and sidewalks
to reduce nutrient pollution to surface waterbodies.
Minimize thatch development by mowing at appropriate frequencies and heights for the grass type,
avoiding overwatering, preventing over fertilization, and aerating the turf.
1 These practice guidelines have been adapted from the GreenCO Best Management Practices for the
Conservation and Protection of Water Quality in Colorado: Moving Toward Sustainability (GreenCO
and WWE 2008). See this manual for additional detail and references.
S-9 Landscape Maintenance
LM-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Phosphorus
Phosphorus is commonly overused
and application should be based on
soil tests. Phosphorus washing into
surface waterbodies leads to
excessive algae growth.
Phosphorous does not move out of
the soil like nitrogen, so constant
additions are unnecessary.
Soil Testing
There are several qualified laboratories in Colorado that provide soils tests to determine
recommendations for fertilizer type and application rates. There are also commercially available
quick test kits that are less accurate but could be used by a homeowner. Without an analysis, a
homeowner may be buying unnecessary fertilizer or applying too much. A $20 to $40 soil analysis
has potential to save an owner much more.
The CSU Extension program offers a soil testing service. Contact the CSU Extension for your
county or visit http://www.ext.colostate.edu for more information including a list of laboratories.
Lawn Aeration
Aerate turf once or twice per year, as needed, in the early spring and/or late fall to aid in capturing the
natural precipitation during non-weed germination periods and prior to adding organic materials and
fertilizers. Aeration reduces soil compaction and helps control thatch in lawns while helping water
and fertilizer move into the root zone.
A lawn can be aerated at any time the ground is not frozen, but should not be done when it is
extremely hot and dry. Heavy traffic areas will require aeration more frequently.
Do not use spike-type aerators, which compact the
soil. Holes should be two to three inches deep and
no more than two to four inches apart. Lawns
should be thoroughly watered the day before
aerating so plugs can be pulled more deeply and
easily. Mark all sprinkler heads, shallow irrigation
lines, and buried cable TV lines before aerating so
those lines will not be damaged.
Fertilizer Application
Apply fertilizer when needed to achieve a clearly
defined objective such as increasing shoot growth,
root growth, flowering or fruiting; enhancing
foliage color, and plant appearance; or correcting
or preventing nutrient deficiencies.
Because manufactured fertilizers can be relatively
high in nutrient content, it is critical to follow the
manufacturer's directions, using the minimum
amount recommended. Over-application "burns"
leaves and may lead to water pollution, thatch buildup, excessive mowing, and weed growth.
Only apply nutrients the plants can use. Fertilizer labels identify product contents in terms of ratios
that indicate percentage of ingredients by product weight.
Landscape Maintenance S-9
November 2010 Urban Drainage and Flood Control District LM-3
Urban Storm Drainage Criteria Manual Volume 3
When practical and appropriate, base fertilizer application on soil analysis. Be aware that at many
new development sites, soil conditions following grading often no longer consist of topsoil.
"Basement" soils with poor texture and low nutrient content may be present. As a result, soil
amendment is often needed to improve the physical properties (tilth) of the soil to provide a better
environment for plant roots to improve nutrient uptake. Soil analysis can help to identify soil
amendments that improve both the physical and nutrient characteristics of the soil, as well as identify
fertilization requirements.
Utilize split applications of slow-release (controlled-release) fertilizer forms such as IBDU, sulfur-
coated urea and natural organic-based fertilizers (not to be confused with raw manure) to minimize
the risk of nutrients leaching into groundwater or running off in surface water. When properly
applied, other forms of fertilizer can also be safely used, provided that over-watering and over-
fertilization do not occur.
When applying fertilizer, broadcast it uniformly over the targeted area of the landscape. Keep
fertilizer off streets, sidewalks, and driveways to prevent water pollution. Fertilizer that inadvertently
falls on impervious surfaces should be swept back onto the lawn.
Recommendations for fertilizer application vary among industry professionals. CSU Extension's
fertilizer recommendations for established Colorado lawns are provided in the table below. Site-
specific conditions should also be considered when determining the need for fertilizer.
Table LM-1. CSU Extension Recommendations for
Nitrogen Application Rate
Nitrogen Application Rate in Pounds/1,000 sq. ft.
Turfgrass Species Mid-March to
AprilA,B
May to Mid-
June B
July to
Early
August B
Mid-August to
Mid-
SeptemberB, C
Early October to
Early NovemberB,
D
High Maintenance
Bluegrass Ryegrass 0.5-1 1 Not
Required 1 1-2 (optional)
Low Maintenance
Bluegrass 0.5 0.5-1 Not
Required 1 1 (optional)
Tall Fescue 0.5 0.5-1 Not
Required 1 1 (optional)
Fine Fescue 0.5 0.5-1 Not
Required 0.5-1 None
Buffalo grass, Blue
Grama, Bermuda
grass
None 0.5-1 0.5-1 None None
Notes:
A The March-April nitrogen application may not be needed if prior fall fertilization was completed. If spring green-
up and growth is satisfactory, delay fertilizing to May or June.
B Application rates may be reduced by 1/4 to 1/3 when grass clippings are left on the lawn.
C On very sandy soils do not fertilize turf after late September to prevent nitrogen from leaching into groundwater
during the winter months.
D Apply when the grass is still green and at least 2-3 weeks prior to the ground freezing. Optional nitrogen
applications are indicated for use where higher quality or heavily-used turf is present.
Source: T. Koski and V. Skinner, CSU Extension, 2003.
S-9 Landscape Maintenance
LM-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
If possible, properly irrigate turf following fertilization to help grass utilize applied nutrients and to
minimize the potential for fertilizer burn. Care should be taken to avoid excessive irrigation that
would result in fertilizer being washed away. Similarly, avoid application of fertilizer immediately
prior to heavy rainfall.
Fall is the best time of year to fertilize bluegrass lawns. Over-application of nitrogen fertilizer in
April may cause grass to grow too fast before roots can support the growth, resulting in less heat
tolerance.
Generally, the Colorado Nursery and Greenhouse Association recommends waiting until the second
growing season to fertilize ornamental (woody) plants. Commercial fertilizer should not be used in
the backfill where it comes in direct contact with the roots.
Maintain a buffer zone around wells or surface waterbodies where fertilizers are not applied to
minimize pollution. Consult the fertilizer product label and local regulations and landscape
ordinances for appropriate distances. Research in this area is limited; however, CSU Extension
recommends a buffer of 6 to 10 feet for mowed turf areas.
In areas with sandy soils, it is particularly important to avoid over-application of fertilizer that could
leach into groundwater. These areas may be particularly well suited to slow-release fertilizer forms
and conservative application rates.
Lawn Irrigation
The approximate amount of water that needs to be applied each week for an average, traditional lawn
to supplement normal rainfall is listed in Table 2. (Water utilities may provide additional guidance in
terms of suggested run-times for various sprinkler types; http://www.denverwater.org/Conservation/.)
Table LM-2. General Guideline for Approximate Supplemental Water
for an Average Traditional Lawn (inches per week)
Condition3 April1 May June July Aug Sept Oct2
Non-Drought
Conditions 1/4" 1" 1½" 1½" 1¼" 1" 1/2"
During Drought
Restrictions (approx.
20% reduction) 1/4" 3/4" 1¼" 1¼" 1" 3/4" 1/2"
1 For established lawns, water may not be required during April. Base decision on weather conditions.
2 For established lawns, water is typically not required after Oct 15.
3Under less-than-average rainfall conditions, the amounts shown in the chart should be increased. If
there is greater-than-normal rainfall, then the amount of supplemental water should be reduced.
Consult with the CSU Extension Turfgrass program for recommendations for irrigating turfgrasses
with lower water requirements (e.g. blue grama, buffalo grass). For native grasses, irrigation may be
unnecessary or limited to certain conditions.
Irrigate the lawn uniformly until the soil is moist to a depth of 4 to 6 inches to encourage deep roots.
Frequent, light sprinklings moisten only the surface and may cause shallow-rooted turf and increase
weed seed germination. Properly maintain the irrigation system to ensure that the irrigation is being
applied at appropriate rates and to the turfgrass, not the sidewalk.
Landscape Maintenance S-9
November 2010 Urban Drainage and Flood Control District LM-5
Urban Storm Drainage Criteria Manual Volume 3
Maintain irrigation systems in good operating condition with uniform distribution of water. "Smart"
irrigation controllers and weather sensors can reduce water waste by shutting off irrigation during
storm events and helping owners water according to the needs of the plants to replace water lost to
evapotranspiration (ET).
Proper irrigation can minimize the amount of fertilizer and other chemicals that are leached below the
root zone of the grass or washed away by runoff.
Snow and Ice Management S-10
November 2010 Urban Drainage and Flood Control District SIM -1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SIM-1. Snow storage locations should be clearly
communicated to snow removal contractors and located where they can
drain to stormwater BMPs or landscaped areas. Photo courtesy of
WWE.
Description
For obvious safety reasons, snow
removal in Colorado is important;
however, snow removal and
management practices can adversely
impact vegetation, soils, water quality,
and air quality. Snow removal
contractors and operators should be
knowledgeable of these potential
impacts and choose management
measures with the fewest adverse
impacts, while still protecting the public
safety, health and welfare.
Appropriate Uses
Snow and ice management procedures
are relevant for homeowners, contractors,
business owners, and transportation departments.
Practice Guidelines 1
Physical removal of snow and ice by shovels, snowplows, or snow blowers usually has the least water
quality and landscape impacts, provided that storage areas are not piled directly on landscape plants
or drained directly to receiving waters. Plan for snow storage locations that minimize water quality
and landscape impacts prior to winter.
Ensure that equipment is calibrated to optimum levels according to manufacturer’s instructions.
Consider placing barriers in targeted site-specific locations (i.e., along streams or direct drainages) to
route deicing material away from waterbodies.
Reduce plowing speed in sensitive areas to prevent exposure to deicing material.
Designate snow storage areas in locations that enable runoff to be directed to stormwater BMPs for
treatment, when practicable.
The use of deicing chemicals can have a severe impact on plants growing near roads and sidewalks.
This can become a water quality issue when plants die and erosion results. Many deicing chemicals
are salts and can adversely affect plants through either direct contact with foliage or through buildup
in the soil over time. Representative impacts include:
1These practice guidelines have been adapted from the GreenCO Best Management Practices for the
Conservation and Protection of Water Quality in Colorado: Moving Toward Sustainability (GreenCO
and WWE 2008). See this manual for additional detail and references.
S-10 Snow and Ice Management
SIM -2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
o Direct contact often occurs when the deicing chemicals accumulate on the plants due to drift
during application, or when snow or ice containing the chemical is shoveled or blown onto nearby
plants. Because these chemicals are salts, direct contact with the foliage may result in burning
due to a rapid dehydration effect.
o Buildup of de-icing chemicals in the soil may have even more detrimental effects. Repeated
application over time (either during a particular winter season or over many seasons) may damage
plants by making their roots unable to take up water. Symptoms will include wilting even when
the soil is moist, leaf burn or needle tip burn, stunting or lack of vigor, and/or deficiency
symptoms for one or more plant nutrients. The structure of clay soils can be changed to the point
that they are unable to support plant life.
Deicing chemicals that are considered safer to use around plants include calcium magnesium acetate
(CMA) or calcium chloride. As with all chemicals used in the landscape, be sure to read and follow
label instructions and do not over apply.
The Colorado Department of Transportation (CDOT) has conducted multiple studies on deicing
chemicals. The SeaCrest Group (2001) studied three groups of deicers for CDOT that were chloride-
based, acetate-based, and sanding materials. The chloride-based deicers included magnesium
chloride (FreezGard Zero® with Shield LS®, Ice-Stop™ CI, Caliber™ M1000, Ice Ban™ M50),
calcium chloride (Liquidow®, Armor®), and sodium chloride (road salt and Ice Slicer®). The
acetate-based deicers include Calcium Magnesium Acetate (CMA®), Potassium Acetate (CF7®),
Sodium Acetate (NAAC®), and CMAK™ (a mixture of CMA and Potassium Acetate). Table 1
contains a partial summary of the study findings.
Highlights of the SeaCrest (2001) study regarding impacts associated with the three categories
include:
o The chloride-based deicers have been shown to have adverse effects on terrestrial vegetation.
Damage to vegetation from deicing salts has been reported to a distance of 100-650 feet.
However, there is a wide range of tolerance of different species of plants to the effects of
chlorides. The chloride ions in deicers increase the salinity of the soil near the roadways where
they are applied. The magnesium and calcium ions increase the stability and permeability of the
soil, whereas sodium ions decrease soil stability and permeability.
o The acetate-based deicers are organic and have different kinds of effects on the environment than
the chloride-based deicers. The acetate ions are broken down by soil microorganisms and may
result in oxygen depletion of the soil, which can impact vegetation; however, the acetate deicers
CMA and Potassium Acetate (CMAK) are not harmful to terrestrial vegetation at the
concentrations typically used on roadways. However, NAAC may potentially have an adverse
effect on vegetation because of the presence of the sodium ion, which decreases the stability and
permeability of the soil. The depletion of oxygen in the soil from the breakdown of the acetate
ion can have a negative effect on plant growth, but field evidence of this effect is limited.
o Sand is not a deicer, but is used for snow and ice control because it improves traction. Sand has a
negative effect on water quality as a result of the increased turbidity caused by the presence of
sand particles in water. Excessive quantities of sand can smother vegetation.
Snow and Ice Management S-10
November 2010 Urban Drainage and Flood Control District SIM -3
Urban Storm Drainage Criteria Manual Volume 3
Table SIM-1. Potential Environmental Impacts of Various Deicers
(Source: The SeaCrest Group 2001)2
Deicer/
Parameter
Inhibited
Magnesium
Chloride
(Liquid)
Caliber +
Magnesium
Chloride
(Liquid)
Ice Ban +
Magnesium
Chloride
(Liquid)
Sodium
Chloride/ Ice
Slicer (Solid)
Inhibited
Calcium
Chloride
(Liquid)
CMA
(Solid/
Liquid)
CMAK
(Liquid)
Potassium
Acetate
(Liquid)
NAAC
(Solid) Sand
Chemicals
Trace metals
Trace metals,
phosphorus,
ammonia
Trace metals,
phosphorus,
ammonia,
nitrates
Trace metals
Trace
metals,
ammonia,
nitrates.
Trace
metals
Trace
metals,
ammonia,
nitrates.
Trace metals
Trace
metals,
phosphorus
Trace metals
Soil
Improves
structure,
increases
salinity
Improves
structure,
increases
salinity,
oxygen
depletion
Improves
structure,
increases
salinity,
oxygen
depletion
Increases
salinity;
decreases
stability
Improves
structure,
increases
salinity
Improves
structure;
oxygen
depletion
Improves
structure;
oxygen
depletion
Improves
structure;
oxygen
depletion
Decreases
stability;
oxygen
depletion
Minimal effects
Water
Quality
Increases
salinity
Increases
salinity;
oxygen
depletion
Increases
salinity;
oxygen
depletion
Increases
salinity
Increases
salinity
Oxygen
depletion
Oxygen
depletion
Oxygen
depletion
Increases
turbidity
Air Quality
Minimal air
pollution
Minimal air
pollution
Minimal air
pollution
Some air
pollution
Minimal air
pollution
Minimal air
pollution
Minimal air
pollution
Minimal air
pollution
Some air
pollution
High air pollution
potential
Aquatic
Organisms
Relatively
low toxicity
Relatively low
toxicity
Moderate
toxicity
Relatively
low toxicity
Relatively
low toxicity
Relatively
low toxicity
Moderate
toxicity
Moderate
toxicity
Relatively
low toxicity
Can cover
benthic
organisms and
cause mortality
Terrestrial
Vegetation
Chlorides
damage
vegetation
Chlorides
damage
vegetation
Chlorides
damage
vegetation
Chlorides
damage
vegetation
Chlorides
damage
vegetation
Minimal
damage to
vegetation
Minimal
damage to
vegetation
Minimal
damage to
vegetation
Effects to
vegetation
not
determined
Can cover
vegetation and
cause mortality
Terrestrial
Animals
Does not
attract
wildlife
Does not
attract wildlife
Does not
attract wildlife
Attracts
wildlife
contributing
to road kills
Does not
attract
wildlife
Not
expected to
attract
wildlife
Not
expected to
attract
wildlife
Not expected
to attract
wildlife
May attract
wildlife
contributing
to roadkills
May cover
burrows of small
animals and
cause mortality
Note: Trace metals that may be present include arsenic, barium, cadmium, chromium, copper, lead, mercury,
selenium, and zinc. Soil comments related to structure refer to the affect on soil stability, which relates to erosion.
See http://www.coloradodot.info/programs/research/pdfs/2001/deicers.pdf/view for more information.
Where practicable, do not use deicers to melt snow or ice completely, but to make their removal
easier. Deicers melt down through the ice or snow to the hard surface, then spread out underneath.
This undercuts and loosens the snow so shoveling and plowing can be done. For this reason, it is
helpful to apply deicers prior to snow events in some cases.
Research has shown that the shape of deicing particles affects the speed of their penetration through
ice. Uniformly shaped spherical pellets of about 1/16 inch to 3/16 inch penetrate ice faster and more
efficiently than other shapes.
Try to avoid the use of rock salt since it is generally most damaging to plants, soils and concrete and
metal surfaces. In areas where deicing salts are unavoidable, select plants with higher salt tolerances.
2 The SeaCrest Group, 2001. Evaluation of Selected Deicers Based on a Review of the Literature, Report No. CDOT-DTD-
2001-15. Prepared for Colorado Department of Transportation Research Branch.
S-10 Snow and Ice Management
SIM -4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Do not plow snow directly into streams or wetlands. Snow storage and disposal areas should be
located in an area where snowmelt can infiltrate into the ground, filter through a vegetated buffer or
be otherwise treated prior to reaching streams and wetlands. Provide adequate storage volume to trap
sediment left behind by melting snow and plan regular maintenance to remove accumulated sediment.
In areas subject to heavy chemical deicing use, flushing the soil with water after the last freeze may
alleviate burn potential. Year-round proper plant care will also make plants more tolerant to salt
exposure. However, for the overall health of the landscape, the goal should be to reduce or minimize
the use of deicing chemicals where they are not necessary for safety reasons.
If an electric/mechanical snow melting device is used to dispose of removed snow (e.g., The Can
snow melter, Snow Dragon, etc.), the owner or operator must obtain the appropriate permit prior to
discharge. Snowmelt from melting machines is typically considered process wastewater.
Street Sweeping and Cleaning S-11
November 2010 Urban Drainage and Flood Control District SWC-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SSC-1. Monthly street sweeping from April through
November removed nearly 40,690 cubic yards of sediment/debris from
Denver streets in 2009. Photo courtesy of Denver Public Works.
Description
Street sweeping uses mechanical pavement
cleaning practices to reduce sediment,
litter and other debris washed into storm
sewers by runoff. This can reduce
pollutant loading to receiving waters and
in some cases reduce clogging of storm
sewers and prolong the life of infiltration
oriented BMPs and reduce clogging of
outlet structures in detention BMPs.
Different designs are available with typical
sweepers categorized as a broom and
conveyor belt sweeper, wet or dry
vacuum-assisted sweepers, and
regenerative-air sweepers. The
effectiveness of street sweeping is
dependent upon particle loadings in the
area being swept, street texture, moisture
conditions, parked car management,
equipment operating conditions and
frequency of cleaning (Pitt et al. 2004).
Appropriate Uses
Street sweeping is an appropriate technique in urban areas where sediment and litter accumulation on
streets is of concern for aesthetic, sanitary, water quality, and air quality reasons. From a pollutant
loading perspective, street cleaning equipment can be most effective in areas where the surface to be
cleaned is the major source of contaminants. These areas include freeways, large commercial parking
lots, and paved storage areas (Pitt et al. 2004). Where significant sediment accumulation occurs on
pervious surfaces tributary to infiltration BMPs, street sweeping may help to reduce clogging of
infiltration media. In areas where construction activity is occurring, street sweeping should occur as part
of construction site stormwater management plans. Vacuuming of permeable pavement systems is also
considered a basic routine maintenance practice to maintain the BMP in effective operating condition.
See the maintenance chapter for more information on permeable pavement systems. Not all sweepers are
appropriate for this application.
Practice Guidelines 1
1. Post street sweeping schedules with signs and on local government websites so that cars are not
parked on the street during designated sweeping days.
2. Sweeping frequency is dependent on local government budget, staffing, and equipment availability,
but monthly sweeping during non-winter months is a common approach in the metro Denver urban
1 Practice guidelines adapted from CASQA (2003) California Stormwater BMP Handbook, Practice SC-70 Road and Street
Maintenance.
S-11 Street Sweeping and Cleaning
SWC-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Changes in Street Sweeper Technology (Source: Center for Watershed Protection 2002)
At one time, street sweepers were thought to have great potential to remove stormwater pollutants from
urban street surfaces and were widely touted as a stormwater treatment practice in many communities.
Street sweeping gradually fell out of favor, largely as a result of performance monitoring conducted as
part of the National Urban Runoff Program (NURP). These studies generally concluded that street
sweepers were not very effective in reducing pollutant loads (USEPA, 1983). The primary reason for
the mediocre performance was that mechanical sweepers of that era were unable to pick up fine-grained
sediment particles that carry a substantial portion of the stormwater pollutant load. In addition, the
performance of sweepers is constrained by that portion of a street’s stormwater pollutant load delivered
from outside street pavements (e.g., pollutants that wash onto the street from adjacent areas or are
directly deposited on the street by rainfall). Street sweeping technology, however, has evolved
considerably since the days of the NURP testing. Today, communities have a choice in three basic
sweeping technologies to clean their urban streets: traditional mechanical sweepers that utilize a broom
and conveyor belt, vacuum-assisted sweepers, and regenerative-air sweepers (those that blast air onto
the pavement to loosen sediment particles and vacuum them into a hopper).
For more information, see
http://www.cwp.org/Resource_Library/Center_Docs/PWP/ELC_PWP121.pdf
area. Consider increasing sweeping frequency based on factors such as traffic volume, land use, field
observations of sediment and trash accumulation, proximity to watercourses, etc. For example:
Increase the sweeping frequency for streets with high pollutant loadings, especially in high traffic
and industrial areas.
Conduct street sweeping prior to wetter seasons to remove accumulated sediments.
Increase the sweeping frequency for streets in special problem areas such as special events, high
litter or erosion zones.
3. Perform street cleaning during dry weather if possible.
4. Avoid wet cleaning the street; instead, utilize dry methods where possible.
5. Maintain cleaning equipment in good working condition and purchase replacement equipment as
needed. Old sweepers should be replaced with more technologically advanced sweepers (preferably
regenerative air sweepers) that maximize pollutant removal.
6. Operate sweepers at manufacturer recommended optimal speed levels to increase effectiveness.
7. Regularly inspect vehicles and equipment for leaks and repair promptly.
8. Keep accurate logs of the number of curb-miles swept and the amount of waste collected.
9. Dispose of street sweeping debris and dirt at a landfill.
10. Do not store swept material along the side of the street or near a storm drain inlet.
Storm Sewer System Cleaning S-12
November 2010 Urban Drainage and Flood Control District SSC-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SSC-1. Storm drain cleaning may help to remove
pollutant sources and helps to maintain the capacity of the storm pipes.
Description 1
Periodic storm sewer system cleaning
can help to remove accumulated
sediment, trash, and other substances
from various components of the storm
sewer system including inlets, pipes and
stormwater BMPs. Some common
pollutants found in storm drains include:
trash and debris, sediments, oil and
grease, antifreeze, paints, cleaners and
solvents, pesticides, fertilizers, animal
waste, and detergents. Routine cleaning
reduces the amount of pollutants, trash,
and debris both in the storm drain system
and in receiving waters. Clogged drains
and storm drain inlets can cause the
drains to overflow, leading to increased
erosion (Livingston et al. 1997).
Cleaning increases dissolved oxygen, reduces levels of bacteria, and supports in-stream habitat. Areas
with relatively flat grades or low flows should be given special attention because they rarely achieve high
enough flows to flush themselves (Ferguson et al. 1997).
Appropriate Uses
Storm sewer system cleaning is typically conducted by local governments or state agencies; however,
homeowners associations, businesses and industries are usually responsible for maintaining system
components on their sites.
Due to the cost and time involved with storm sewer system cleaning, communities may target recurrent
problem areas or use another type of prioritization system for maintenance. Also see the BMP
Maintenance chapter for BMP-specific maintenance requirements.
Practice Guidelines
A variety of jet/vacuum vehicles can be used to remove debris from stormwater catch basins and pipes.
This equipment breaks up clogged/accumulated material with high-pressure water jets and vacuums the
material from the sewer. Water used in storm drain cleaning must be collected and properly disposed of,
typically at a sanitary wastewater treatment facility.
Simpler methods in localized areas can also include manual trash collection and shoveling from inlets and
outlets.
1 Guidelines adapted from Center for Watershed Protection (2009) Urban Stormwater Restoration Manual Series 8: Municipal
Practices and Programs.
S-12 Storm Sewer System Cleaning
SSC-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Frequency and prioritization of storm sewer cleaning is affected by multiple factors such as the activity
and intensity of use in the tributary area (e.g., parking lot, stadium), storm sewer system design,
municipal budgets (staff and equipment), and other factors.
To be most effective, storm sewer cleaning needs an effective recordkeeping system and clearly defined
procedures. CWP (2009) recommends the following practices:
Tracking: The location and maintenance of storm drains should be tracked using a database and
spatial referencing system (e.g., Global Positioning System or Geographic Information System).
Additionally, knowing the type and era of the storm drain system may be of use since some
inlets/catch basins are designed to be self-cleaning while others have some trapping capacity.
Frequency: Should be defined such that blockage of storm sewer outlet is prevented and it is
recommended that the sump should not exceed 40- 50 percent of its capacity. Semi-annual cleanouts
in residential streets and monthly cleanouts for industrial streets are suggested by Pitt and Bissonnett
(1984) and Mineart and Singh (1994). More frequent cleanouts should be scheduled in the fall as
leaves can contribute 25% of nutrient loadings in catch basins.
Technology: A variety of methods of cleaning catch basins are available, including manual cleaning,
eductor vehicles, vacuum cleaning and vacuum combination jet cleaning. Choose the approach that is
most effective for site conditions, taking into consideration budget, equipment, and staffing
constraints.
Staff training: Operators need to be properly trained in catch basin maintenance including waste
collection and disposal methods. Staff should also be trained to report water quality problems and
illicit discharges.
Material disposal: Most catch basin waste is of acceptable quality for landfills. If it is suspected
that catch basin waste contains hazardous material, it should be tested and disposed of accordingly.
Maintenance personnel should keep a log of the amount of sediment collected and the removal date at
the catch basin.
Surface Roughening (SR) EC-1
November 2010 Urban Drainage and Flood Control District SR-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SR-1. Surface roughening via imprinting for temporary
stabilization.
Description
Surface roughening is an erosion control
practice that involves tracking,
scarifying, imprinting, or tilling a
disturbed area to provide temporary
stabilization of disturbed areas. Surface
roughening creates variations in the soil
surface that help to minimize wind and
water erosion. Depending on the
technique used, surface roughening may
also help establish conditions favorable
to establishment of vegetation.
Appropriate Uses
Surface roughening can be used to
provide temporary stabilization of
disturbed areas, such as when
revegetation cannot be immediately established due to seasonal planting limitations. Surface roughening
is not a stand-alone BMP, and should be used in conjunction with other erosion and sediment controls.
Surface roughening is often implemented in conjunction with grading and is typically performed using
heavy construction equipment to track the surface. Be aware that tracking with heavy equipment will also
compact soils, which is not desirable in areas that will be revegetated. Scarifying, tilling, or ripping are
better surface roughening techniques in locations where revegetation is planned. Roughening is not
effective in very sandy soils and cannot be effectively performed in rocky soil.
Design and Installation
Typical design details for surfacing roughening on steep and mild slopes are provided in Details SR-1 and
SR-2, respectively.
Surface roughening should be performed either after final grading or to temporarily stabilize an area
during active construction that may be inactive for a short time period. Surface roughening should create
depressions 2 to 6 inches deep and approximately 6 inches apart. The surface of exposed soil can be
roughened by a number of techniques and equipment. Horizontal grooves (running parallel to the
contours of the land) can be made using tracks from equipment treads, stair-step grading, ripping, or
tilling.
Fill slopes can be constructed with a roughened surface. Cut slopes that have been smooth graded can be
roughened as a subsequent operation. Roughening should follow along the contours of the slope. The
tracks left by truck mounted equipment working perpendicular
to the contour can leave acceptable horizontal depressions;
however, the equipment will also compact the soil.
Surface Roughening
Functions
Erosion Control Yes
Sediment Control No
Site/Material Management No
EC-1 Surface Roughening (SR)
SR-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Maintenance and Removal
Care should be taken not to drive vehicles or equipment over areas that have been surface roughened.
Tire tracks will smooth the roughened surface and may cause runoff to collect into rills and gullies.
Because surface roughening is only a temporary control, additional treatments may be necessary to
maintain the soil surface in a roughened condition.
Areas should be inspected for signs of erosion. Surface roughening is a temporary measure, and will not
provide long-term erosion control.
Surface Roughening (SR) EC-1
November 2010 Urban Drainage and Flood Control District SR-3
Urban Storm Drainage Criteria Manual Volume 3
EC-1 Surface Roughening (SR)
SR-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Temporary and Permanent Seeding (TS/PS) EC-2
January 2021 Urban Drainage and Flood Control District TS/PS-1
Urban Storm Drainage Criteria Manual Volume 3
Description
Temporary seeding can be used to
stabilize disturbed areas that will be
inactive for an extended period.
Permanent seeding should be used to
stabilize areas at final grade that will not
be otherwise stabilized. Effective seeding
includes preparing a seedbed, selecting an
appropriate seed mixture, using proper
planting techniques, and protecting the
seeded area with mulch, geotextiles, or
other appropriate measures.
Appropriate Uses
When the soil surface is disturbed and
will remain inactive for an extended
period (typically determined by local
government requirements), proactive
stabilization measures, including planting a temporary seed mix, should be implemented. If the inactive
period is short-lived (on the order of two weeks), techniques such as surface roughening may be
appropriate. For longer periods of inactivity of up to one year, temporary seeding and mulching can
provide effective erosion control. Permanent seeding should be used on finished areas that have not been
otherwise stabilized.
The USDCM Volume 2 Revegetation Chapter contains suggested annual grains and native seed mixes to
use for temporary seeding. Alternatively, local governments may have their own seed mixes and timelines
for seeding. Check jurisdictional requirements for seeding and temporary stabilization.
Design and Installation
Effective seeding requires proper seedbed preparation, selecting an appropriate seed mixture, using
appropriate seeding equipment to ensure proper coverage and density, and protecting seeded areas with
mulch or fabric until plants are established.
The USDCM Volume 2 Revegetation Chapter contains detailed seed mixes, soil preparation practices,
and seeding and mulching recommendations that should be referenced to supplement this Fact Sheet.
Drill seeding is the preferred seeding method. Hydroseeding is not recommended except in areas where
steep slopes prevent use of drill seeding equipment, and even in these instances it is preferable to hand
seed and mulch. Some jurisdictions do not allow
hydroseeding or hydromulching.
Seedbed Preparation
Prior to seeding, ensure that areas to be revegetated have
soil conditions capable of supporting vegetation. Overlot
grading can result in loss of topsoil and compaction,
resulting in poor quality subsoils at the ground surface that
Temporary and Permanent Seeding
Functions
Erosion Control Yes
Sediment Control No
Site/Material Management No
Photograph TS/PS -1. Equipment used to drill seed. Photo courtesy of
Douglas County.
EC-2 Temporary and Permanent Seeding (TS/PS)
TS/PS-2 Urban Drainage and Flood Control District January 2021
Urban Storm Drainage Criteria Manual Volume 3
have low nutrient value, little organic matter content, few soil microorganisms, rooting restrictions, and
conditions less conducive to infiltration of precipitation. As a result, it is typically necessary to provide
stockpiled topsoil, compost, or other soil amendments and rototill them into the soil to a depth of 6 inches
or more.
Topsoil should be salvaged during grading operations for use and spread on areas to be revegetated later.
Topsoil should be viewed as an important resource to be utilized for vegetation establishment, due to its
water-holding capacity, structure, texture, organic matter content, biological activity, and nutrient content.
The rooting depth of most native grasses in the semi-arid Denver metropolitan area is 6 to 18 inches. If
present, at a minimum of the upper 6 inches of topsoil should be stripped, stockpiled, and ultimately
respread across areas that will be revegetated.
Where topsoil is not available, subsoils should be amended to provide an appropriate plant-growth
medium. Organic matter, such as well digested compost, can be added to improve soil characteristics
conducive to plant growth. Other treatments can be used to adjust soil pH conditions when needed. Soil
testing, which is typically inexpensive, should be completed to determine and optimize the types and
amounts of amendments that are required.
If the disturbed ground surface is compacted, rip or rototill the upper 12 inches of the surface prior to
placing topsoil. If adding compost to the existing soil surface, rototilling is necessary. Surface
roughening will assist in placing a stable topsoil layer on steeper slopes, and allow infiltration and root
penetration to greater depth. Topsoil should not be placed when either the salvaged topsoil or receiving
ground are frozen or snow covered.
Prior to seeding, the soil surface should be rough and the seedbed should be firm, but neither too loose
nor compacted. The upper layer of soil should be in a condition suitable for seeding at the proper depth
and conducive to plant growth. Seed-to-soil contact is the key to good germination.
Refer to MHFD’s Topsoil Management Guidance for detailed information on topsoil assessment, design,
and construction.
Temporary Vegetation
To provide temporary vegetative cover on disturbed areas which will not be paved, built upon, or fully
landscaped or worked for an extended period (typically 30 days or more), plant an annual grass
appropriate for the time of planting and mulch the planted areas. Temporary grain seed mixes suitable for
the Denver metropolitan area are listed in Table TS/PS-1. Native temporary seed mixes are provided in
USDCM Volume 2, Chapter 13, Appendix A. These are to be considered only as general
recommendations when specific design guidance for a particular site is not available. Local governments
typically specify seed mixes appropriate for their jurisdiction.
Permanent Revegetation
To provide vegetative cover on disturbed areas that have reached final grade, a perennial grass mix should
be established. Permanent seeding should be performed promptly (typically within 14 days) after
reaching final grade. Each site will have different characteristics and a landscape professional or the local
jurisdiction should be contacted to determine the most suitable seed mix for a specific site. In lieu of a
specific recommendation, one of the perennial grass mixes appropriate for site conditions and growth
season listed in seed mix tables in the USDCM Volume 2 Revegetation Chapter can be used. The pure
live seed (PLS) rates of application recommended in these tables are considered to be absolute minimum
rates for seed applied using proper drill-seeding equipment. These are to be considered only as general
Temporary and Permanent Seeding (TS/PS) EC-2
January 2021 Urban Drainage and Flood Control District TS/PS-3
Urban Storm Drainage Criteria Manual Volume 3
recommendations when specific design guidance for a particular site is not available. Local governments
typically specify seed mixes appropriate for their jurisdiction.
If desired for wildlife habitat or landscape diversity, shrubs such as rubber rabbitbrush (Chrysothamnus
nauseosus), fourwing saltbush (Atriplex canescens) and skunkbrush sumac (Rhus trilobata) could be
added to the upland seed mixes at 0.25, 0.5 and 1 pound PLS/acre, respectively. In riparian zones,
planting root stock of such species as American plum (Prunus americana), woods rose (Rosa woodsii),
plains cottonwood (Populus sargentii), and willow (Salix spp.) may be considered. On non-topsoiled
upland sites, a legume such as Ladak alfalfa at 1 pound PLS/acre can be included as a source of nitrogen
for perennial grasses.
Timing of seeding is an important aspect of the revegetation process. For upland and riparian areas on the
Colorado Front Range, the suitable timing for seeding is from October through May. The most favorable
time to plant non-irrigated areas is during the fall, so that seed can take advantage of winter and spring
moisture. Seed should not be planted if the soil is frozen, snow covered, or wet.
Seeding dates for the highest success probability of perennial species along the Front Range are generally
in the spring from April through early May and in the fall after the first of September until the ground
freezes. If the area is irrigated, seeding may occur in summer months, as well. See Table TS/PS-2 for
appropriate seeding dates.
EC-2 Temporary and Permanent Seeding (TS/PS)
TS/PS-4 Urban Drainage and Flood Control District January 2021
Urban Storm Drainage Criteria Manual Volume 3
Table TS/PS-1. Minimum Drill Seeding Rates for Various Temporary Annual Grasses
Speciesa
(Common name)
Growth
Seasonb
Pounds of
Pure Live Seed
(PLS)/acrec
Planting
Depth
(inches)
1. Oats Cool 35 - 50 1 - 2
2. Spring wheat Cool 25 - 35 1 - 2
3. Spring barley Cool 25 - 35 1 - 2
4. Annual ryegrass Cool 10 - 15 ½
5. Millet Warm 3 - 15 ½ - ¾
6. Winter wheat Cool 20–35 1 - 2
7. Winter barley Cool 20–35 1 - 2
8. Winter rye Cool 20–35 1 - 2
9. Triticale Cool 25–40 1 - 2
a Successful seeding of annual grass resulting in adequate plant growth will
usually produce enough dead-plant residue to provide protection from
wind and water erosion for an additional year. This assumes that the cover
is not disturbed or mowed closer than 8 inches.
Hydraulic seeding may be substituted for drilling only where slopes are
steeper than 3:1 or where access limitations exist. When hydraulic
seeding is used, hydraulic mulching should be applied as a separate
operation, when practical, to prevent the seeds from being encapsulated in
the mulch.
b See Table TS/PS-2 for seeding dates. Irrigation, if consistently applied,
may extend the use of cool season species during the summer months.
c Seeding rates should be doubled if seed is broadcast, or increased by 50
percent if done using a Brillion Drill or by hydraulic seeding.
Temporary and Permanent Seeding (TS/PS) EC-2
January 2021 Urban Drainage and Flood Control District TS/PS-5
Urban Storm Drainage Criteria Manual Volume 3
Table TS/PS-2. Seeding Dates for Annual and Perennial Grasses
Annual Grasses
(Numbers in table reference
species in Table TS/PS-1)
Perennial Grasses
Seeding Dates Warm Cool Warm Cool
January 1–March 15
March 16–April 30 1,2,3
May 1–May 15
May 16–June 30 5
July 1–July 15 5
July 16–August 31
September 1–September 30 6, 7, 8, 9
October 1–December 31
Mulch
Cover seeded areas with mulch or an appropriate rolled erosion control product to promote establishment
of vegetation. Anchor mulch by crimping, netting or use of a non-toxic tackifier. See the USDCM
Volume 2 Revegetation Chapter and Volume 3 Mulching BMP Fact Sheet (EC-04) for additional
guidance.
Maintenance and Removal
Monitor and observe seeded areas to identify areas of poor growth or areas that fail to germinate. Reseed
and mulch these areas, as needed.
If a temporary annual seed was planted, the area should be reseeded with the desired perennial mix when
there will be no further work in the area. To minimize competition between annual and perennial species,
the annual mix needs time to mature and die before seeding the perennial mix. To increase success of the
perennial mix, it should be seeded during the appropriate seeding dates the second year after the
temporary annual mix was seeded. Alternatively, if this timeline is not feasible, the annual mix seed
heads should be removed and then the area seeded with the perennial mix.
An area that has been permanently seeded should have a good stand of vegetation within one growing
season if irrigated and within three growing seasons without irrigation in Colorado. Reseed portions of
the site that fail to germinate or remain bare after the first growing season.
Seeded areas may require irrigation, particularly during extended dry periods. Targeted weed control may
also be necessary.
Protect seeded areas from construction equipment and vehicle access.
Soil Binders (SB) EC-3
November 2010 Urban Drainage and Flood Control District SB-1
Urban Storm Drainage Criteria Manual Volume 3
Description
Soil binders include a broad range of
treatments that can be applied to exposed
soils for temporary stabilization to reduce
wind and water erosion. Soil binders may
be applied alone or as tackifiers in
conjunction with mulching and seeding
applications.
Acknowledgement: This BMP Fact Sheet
has been adapted from the 2003
California Stormwater Quality
Association (CASQA) Stormwater BMP
Handbook: Construction
(www.cabmphandbooks.com).
Appropriate Uses
Soil binders can be used for short-term, temporary stabilization of soils on both mild and steep slopes.
Soil binders are often used in areas where work has temporarily stopped, but is expected to resume before
revegetation can become established. Binders are also useful on stockpiled soils or where temporary or
permanent seeding has occurred.
Prior to selecting a soil binder, check with the state and local jurisdiction to ensure that the chemicals
used in the soil binders are allowed. The water quality impacts of some types of soil binders are relatively
unknown and may not be allowed due to concerns about potential environmental impacts. Soil binders
must be environmentally benign (non-toxic to plant and animal life), easy to apply, easy to maintain,
economical, and should not stain paved or painted surfaces.
Soil binders should not be used in vehicle or pedestrian high traffic areas, due to loss in effectiveness
under these conditions.
Site soil type will dictate appropriate soil binders to be used. Be aware that soil binders may not function
effectively on silt or clay soils or highly compacted areas. Check manufacturer's recommendations for
appropriateness with regard to soil conditions. Some binders may not be suitable for areas with existing
vegetation.
Design and Installation
Properties of common soil binders used for erosion control
are provided in Table SB-1. Design and installation
guidance below are provided for general reference. Follow
the manufacturer's instructions for application rates and
procedures.
Soil Binders
Functions
Erosion Control Yes
Sediment Control No
Site/Material Management Moderate
Photograph SB-1. Tackifier being applied to provide temporary soil
stabilization. Photo courtesy of Douglas County.
EC-3 Soil Binders (SB)
SB-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Table SB-1. Properties of Soil Binders for Erosion Control (Source: CASQA 2003)
Evaluation Criteria
Binder Type
Plant Material
Based
(short lived)
Plant Material
Based
(long lived)
Polymeric
Emulsion Blends
Cementitious-
Based Binders
Resistance to Leaching High High Low to Moderate Moderate
Resistance to Abrasion Moderate Low Moderate to High Moderate to High
Longevity Short to Medium Medium Medium to Long Medium
Minimum Curing Time
before Rain 9 to 18 hours 19 to 24 hours 0 to 24 hours 4 to 8 hours
Compatibility with
Existing Vegetation Good Poor Poor Poor
Mode of Degradation Biodegradable Biodegradable Photodegradable/
Chemically
Degradable
Photodegradable/
Chemically
Degradable
Specialized Application
Equipment
Water Truck or
Hydraulic
Mulcher
Water Truck or
Hydraulic
Mulcher
Water Truck or
Hydraulic Mulcher
Water Truck or
Hydraulic Mulcher
Liquid/Powder Powder Liquid Liquid/Powder Powder
Surface Crusting Yes, but
dissolves on
rewetting
Yes Yes, but dissolves on
rewetting Yes
Clean Up Water Water Water Water
Erosion Control
Application Rate Varies Varies Varies 4,000 to 12,000
lbs/acre Typ.
Soil Binders (SB) EC-3
November 2010 Urban Drainage and Flood Control District SB-3
Urban Storm Drainage Criteria Manual Volume 3
Factors to consider when selecting a soil binder generally include:
Suitability to situation: Consider where the soil binder will be applied, if it needs a high resistance
to leaching or abrasion, and whether it needs to be compatible with existing vegetation. Determine
the length of time soil stabilization will be needed, and if the soil binder will be placed in an area
where it will degrade rapidly. In general, slope steepness is not a discriminating factor.
Soil types and surface materials: Fines and moisture content are key properties of surface
materials. Consider a soil binder's ability to penetrate, likelihood of leaching, and ability to form a
surface crust on the surface materials.
Frequency of application: The frequency of application can be affected by subgrade conditions,
surface type, climate, and maintenance schedule. Frequent applications could lead to high costs.
Application frequency may be minimized if the soil binder has good penetration, low evaporation,
and good longevity. Consider also that frequent application will require frequent equipment clean up.
An overview of major categories of soil binders, corresponding to the types included in Table SB-1
follows.
Plant-Material Based (Short Lived) Binders
Guar: A non-toxic, biodegradable, natural galactomannan-based hydrocolloid treated with dispersant
agents for easy field mixing. It should be mixed with water at the rate of 11 to 15 lbs per 1,000
gallons. Recommended minimum application rates are provided in Table SB-2.
Table SB-2. Application Rates for Guar Soil Stabilizer
Slope (H:V)
Flat 4:1 3:1 2:1 1:1
Application Rate (lb/acre) 40 45 50 60 70
Psyllium: Composed of the finely ground muciloid coating of plantago seeds that is applied as a wet
slurry to the surface of the soil. It dries to form a firm but rewettable membrane that binds soil
particles together but permits germination and growth of seed. Psyllium requires 12 to 18 hours
drying time. Application rates should be from 80 to 200 lbs/acre, with enough water in solution to
allow for a uniform slurry flow.
Starch: Non-ionic, cold-water soluble (pre-gelatinized) granular cornstarch. The material is mixed
with water and applied at the rate of 150 lb/acre. Approximate drying time is 9 to 12 hours.
Plant-Material Based (Long Lived) Binders
Pitch and Rosin Emulsion: Generally, a non-ionic pitch and rosin emulsion has a minimum solids
content of 48 percent. The rosin should be a minimum of 26 percent of the total solids content. The
soil stabilizer should be a non-corrosive, water dilutable emulsion that upon application cures to a
water insoluble binding and cementing agent. For soil erosion control applications, the emulsion is
diluted and should be applied as follows:
o For clayey soil: 5 parts water to 1 part emulsion
EC-3 Soil Binders (SB)
SB-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
o For sandy soil: 10 parts water to 1 part emulsion
Application can be by water truck or hydraulic seeder with the emulsion and product mixture applied
at the rate specified by the manufacturer.
Polymeric Emulsion Blend Binders
Acrylic Copolymers and Polymers: Polymeric soil stabilizers should consist of a liquid or solid
polymer or copolymer with an acrylic base that contains a minimum of 55 percent solids. The
polymeric compound should be handled and mixed in a manner that will not cause foaming or should
contain an anti-foaming agent. The polymeric emulsion should not exceed its shelf life or expiration
date; manufacturers should provide the expiration date. Polymeric soil stabilizer should be readily
miscible in water, non-injurious to seed or animal life, non-flammable, should provide surface soil
stabilization for various soil types without inhibiting water infiltration, and should not re-emulsify
when cured. The applied compound should air cure within a maximum of 36 to 48 hours. Liquid
copolymer should be diluted at a rate of 10 parts water to 1 part polymer and the mixture applied to
soil at a rate of 1,175 gallons/acre.
Liquid Polymers of Methacrylates and Acrylates: This material consists of a tackifier/sealer that is
a liquid polymer of methacrylates and acrylates. It is an aqueous 100 percent acrylic emulsion blend
of 40 percent solids by volume that is free from styrene, acetate, vinyl, ethoxylated surfactants or
silicates. For soil stabilization applications, it is diluted with water in accordance with manufacturer's
recommendations, and applied with a hydraulic seeder at the rate of 20 gallons/acre. Drying time is
12 to 18 hours after application.
Copolymers of Sodium Acrylates and Acrylamides: These materials are non-toxic, dry powders
that are copolymers of sodium acrylate and acrylamide. They are mixed with water and applied to the
soil surface for erosion control at rates that are determined by slope gradient, as summarized in Table
SB-3.
Table SB-3. Application Rates for Copolymers of Sodium Acrylates and Acrylamides
Slope (H:V)
Flat to 5:1 5:1 to 3:1 2:2 to 1:1
Application Rate (lb/acre) 3.0-5.0 5.0-10.0 10.0-20.0
Polyacrylamide and Copolymer of Acrylamide: Linear copolymer polyacrylamide is packaged as
a dry flowable solid. When used as a stand-alone stabilizer, it is diluted at a rate of 11 lb/1,000 gal. of
water and applied at the rate of 5.0 lb/acre.
Hydrocolloid Polymers: Hydrocolloid Polymers are various combinations of dry flowable
polyacrylamides, copolymers, and hydrocolloid polymers that are mixed with water and applied to the
soil surface at rates of 55 to 60 lb/acre. Drying times are 0 to 4 hours.
Cementitious-Based Binders
Gypsum: This formulated gypsum based product readily mixes with water and mulch to form a thin
protective crust on the soil surface. It is composed of high purity gypsum that is ground, calcined and
processed into calcium sulfate hemihydrate with a minimum purity of 86 percent. It is mixed in a
hydraulic seeder and applied at rates 4,000 to 12,000 lb/acre. Drying time is 4 to 8 hours.
Soil Binders (SB) EC-3
November 2010 Urban Drainage and Flood Control District SB-5
Urban Storm Drainage Criteria Manual Volume 3
Installation
After selecting an appropriate soil binder, the untreated soil surface must be prepared before applying the
soil binder. The untreated soil surface must contain sufficient moisture to assist the agent in achieving
uniform distribution. In general, the following steps should be followed:
Follow manufacturer's written recommendations for application rates, pre-wetting of application area,
and cleaning of equipment after use.
Prior to application, roughen embankment and fill areas.
Consider the drying time for the selected soil binder and apply with sufficient time before anticipated
rainfall. Soil binders should not be applied during or immediately before rainfall.
Avoid over spray onto roads, sidewalks, drainage channels, sound walls, existing vegetation, etc.
Soil binders should not be applied to frozen soil, areas with standing water, under freezing or rainy
conditions, or when the temperature is below 40°F during the curing period.
More than one treatment is often necessary, although the second treatment may be diluted or have a
lower application rate.
Generally, soil binders require a minimum curing time of 24 hours before they are fully effective.
Refer to manufacturer's instructions for specific cure time.
For liquid agents:
o Crown or slope ground to avoid ponding.
o Uniformly pre-wet ground at 0.03 to 0.3 gal/yd2 or according to manufacturer's recommendations.
o Apply solution under pressure. Overlap solution 6 to 12 in.
o Allow treated area to cure for the time recommended by the manufacturer, typically at least 24
hours.
o Apply second treatment before first treatment becomes ineffective, using 50 percent application
rate.
o In low humidity, reactivate chemicals by re-wetting with water at 0.1 to 0.2 gal/yd2.
Maintenance and Removal
Soil binders tend to break down due to natural weathering. Weathering rates depend on a variety of site-
specific and product characteristics. Consult the manufacturer for recommended reapplication rates and
reapply the selected soil binder as needed to maintain effectiveness.
Soil binders can fail after heavy rainfall events and may require reapplication. In particular, soil binders
will generally experience spot failures during heavy rainfall events. If runoff penetrates the soil at the top
of a slope treated with a soil binder, it is likely that the runoff will undercut the stabilized soil layer and
discharge at a point further down slope.
EC-3 Soil Binders (SB)
SB-6 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Areas where erosion is evident should be repaired and soil binder or other stabilization reapplied, as
needed. Care should be exercised to minimize the damage to protected areas while making repairs.
Most binders biodegrade after exposure to sun, oxidation, heat and biological organisms; therefore,
removal of the soil binder is not typically required.
Mulching (MU) EC-4
June 2012 Urban Drainage and Flood Control District MU-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph MU-1. An area that was recently seeded, mulched,
and crimped.
Description
Mulching consists of evenly applying
straw, hay, shredded wood mulch, rock,
bark or compost to disturbed soils and
securing the mulch by crimping, tackifiers,
netting or other measures. Mulching helps
reduce erosion by protecting bare soil
from rainfall impact, increasing
infiltration, and reducing runoff.
Although often applied in conjunction
with temporary or permanent seeding, it
can also be used for temporary
stabilization of areas that cannot be
reseeded due to seasonal constraints.
Mulch can be applied either using
standard mechanical dry application
methods or using hydromulching equipment
that hydraulically applies a slurry of water,
wood fiber mulch, and often a tackifier.
Appropriate Uses
Use mulch in conjunction with seeding to help protect the seedbed and stabilize the soil. Mulch can also
be used as a temporary cover on low to mild slopes to help temporarily stabilize disturbed areas where
growing season constraints prevent effective reseeding. Disturbed areas should be properly mulched and
tacked, or seeded, mulched and tacked promptly after final grade is reached (typically within no longer
than 14 days) on portions of the site not otherwise permanently stabilized.
Standard dry mulching is encouraged in most jurisdictions; however, hydromulching may not be allowed
in certain jurisdictions or may not be allowed near waterways.
Do not apply mulch during windy conditions.
Design and Installation
Prior to mulching, surface-roughen areas by rolling with a crimping or punching type roller or by track
walking. Track walking should only be used where other methods are impractical because track walking
with heavy equipment typically compacts the soil.
A variety of mulches can be used effectively at construction
sites. Consider the following:
Mulch
Functions
Erosion Control Yes
Sediment Control Moderate
Site/Material Management No
EC-4 Mulching (MU)
MU-2 Urban Drainage and Flood Control District June 2012
Urban Storm Drainage Criteria Manual Volume 3
Clean, weed-free and seed-free cereal grain straw should be applied evenly at a rate of 2 tons per acre and
must be tacked or fastened by a method suitable for the condition of the site. Straw mulch must be
anchored (and not merely placed) on the surface. This can be accomplished mechanically by crimping or
with the aid of tackifiers or nets. Anchoring with a crimping implement is preferred, and is the
recommended method for areas flatter than 3:1. Mechanical crimpers must be capable of tucking the long
mulch fibers into the soil to a depth of 3 inches without cutting them. An agricultural disk, while not an
ideal substitute, may work if the disk blades are dull or blunted and set vertically; however, the frame may
have to be weighted to afford proper soil penetration.
Grass hay may be used in place of straw; however, because hay is comprised of the entire plant including
seed, mulching with hay may seed the site with non-native grass species which might in turn out-compete
the native seed. Alternatively, native species of grass hay may be purchased, but can be difficult to find
and are more expensive than straw. Purchasing and utilizing a certified weed-free straw is an easier and
less costly mulching method. When using grass hay, follow the same guidelines as for straw (provided
above).
On small areas sheltered from the wind and heavy runoff, spraying a tackifier on the mulch is satisfactory
for holding it in place. For steep slopes and special situations where greater control is needed, erosion
control blankets anchored with stakes should be used instead of mulch.
Hydraulic mulching consists of wood cellulose fibers mixed with water and a tackifying agent and should
be applied at a rate of no less than 1,500 pounds per acre (1,425 lbs of fibers mixed with at least 75 lbs of
tackifier) with a hydraulic mulcher. For steeper slopes, up to 2000 pounds per acre may be required for
effective hydroseeding. Hydromulch typically requires up to 24 hours to dry; therefore, it should not be
applied immediately prior to inclement weather. Application to roads, waterways and existing vegetation
should be avoided.
Erosion control mats, blankets, or nets are recommended to help stabilize steep slopes (generally 3:1 and
steeper) and waterways. Depending on the product, these may be used alone or in conjunction with grass
or straw mulch. Normally, use of these products will be restricted to relatively small areas.
Biodegradable mats made of straw and jute, straw-coconut, coconut fiber, or excelsior can be used instead
of mulch. (See the ECM/TRM BMP for more information.)
Some tackifiers or binders may be used to anchor mulch. Check with the local jurisdiction for allowed
tackifiers. Manufacturer's recommendations should be followed at all times. (See the Soil Binder BMP
for more information on general types of tackifiers.)
Rock can also be used as mulch. It provides protection of exposed soils to wind and water erosion and
allows infiltration of precipitation. An aggregate base course can be spread on disturbed areas for
temporary or permanent stabilization. The rock mulch layer should be thick enough to provide full
coverage of exposed soil on the area it is applied.
Maintenance and Removal
After mulching, the bare ground surface should not be more than 10 percent exposed. Reapply mulch, as
needed, to cover bare areas.
Rolled Erosion Control Products (RECP) EC-6
November 2010 Urban Drainage and Flood Control District RECP-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph RECP-1. Erosion control blanket protecting the slope from
erosion and providing favorable conditions for revegetation.
Description
Rolled Erosion Control Products
(RECPs) include a variety of
temporary or permanently installed
manufactured products designed to
control erosion and enhance vegetation
establishment and survivability,
particularly on slopes and in channels.
For applications where natural
vegetation alone will provide sufficient
permanent erosion protection,
temporary products such as netting,
open weave textiles and a variety of
erosion control blankets (ECBs) made
of biodegradable natural materials
(e.g., straw, coconut fiber) can be used.
For applications where natural
vegetation alone will not be sustainable under expected flow conditions, permanent rolled erosion control
products such as turf reinforcement mats (TRMs) can be used. In particular, turf reinforcement mats are
designed for discharges that exert velocities and sheer stresses that exceed the typical limits of mature
natural vegetation.
Appropriate Uses
RECPs can be used to control erosion in conjunction with revegetation efforts, providing seedbed
protection from wind and water erosion. These products are often used on disturbed areas on steep
slopes, in areas with highly erosive soils, or as part of drainageway stabilization. In order to select the
appropriate RECP for site conditions, it is important to have a general understanding of the general types
of these products, their expected longevity, and general characteristics.
The Erosion Control Technology Council (ECTC 2005) characterizes rolled erosion control products
according to these categories:
Mulch control netting: A planar woven natural fiber or extruded geosynthetic mesh used as a
temporary degradable rolled erosion control product to anchor loose fiber mulches.
Open weave textile: A temporary degradable rolled erosion control product composed of processed
natural or polymer yarns woven into a matrix, used to provide erosion control and facilitate
vegetation establishment.
Erosion control blanket (ECB): A temporary
degradable rolled erosion control product composed of
processed natural or polymer fibers which are
mechanically, structurally or chemically bound together
to form a continuous matrix to provide erosion control
and facilitate vegetation establishment. ECBs can be
further differentiated into rapidly degrading single-net
and double-net types or slowly degrading types.
Rolled Erosion Control Products
Functions
Erosion Control Yes
Sediment Control No
Site/Material Management No
EC-6 Rolled Erosion Control Products (RECP)
RECP-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Turf Reinforcement Mat (TRM): A rolled erosion control product composed of non-degradable
synthetic fibers, filaments, nets, wire mesh, and/or other elements, processed into a permanent, three-
dimensional matrix of sufficient thickness. TRMs, which may be supplemented with degradable
components, are designed to impart immediate erosion protection, enhance vegetation establishment
and provide long-term functionality by permanently reinforcing vegetation during and after
maturation. Note: TRMs are typically used in hydraulic applications, such as high flow ditches and
channels, steep slopes, stream banks, and shorelines, where erosive forces may exceed the limits of
natural, unreinforced vegetation or in areas where limited vegetation establishment is anticipated.
Tables RECP-1 and RECP-2 provide guidelines for selecting rolled erosion control products appropriate
to site conditions and desired longevity. Table RECP-1 is for conditions where natural vegetation alone
will provide permanent erosion control, whereas Table RECP-2 is for conditions where vegetation alone
will not be adequately stable to provide long-term erosion protection due to flow or other conditions.
Rolled Erosion Control Products (RECP) EC-6
November 2010 Urban Drainage and Flood Control District RECP-3
Urban Storm Drainage Criteria Manual Volume 3
Table RECP-1. ECTC Standard Specification for Temporary Rolled Erosion Control Products
(Adapted from Erosion Control Technology Council 2005)
Product Description Slope
Applications*
Channel
Applications*
Minimum
Tensile
Strength1
Expected
Longevity
Maximum
Gradient C Factor2,5 Max. Shear
Stress3,4,6
Mulch Control Nets 5:1 (H:V) ≤0.10 @
5:1
0.25 lbs/ft2
(12 Pa)
5 lbs/ft
(0.073 kN/m)
Up to 12
months
Netless Rolled
Erosion Control
Blankets
4:1 (H:V) ≤0.10 @
4:1
0.5 lbs/ft2
(24 Pa)
5 lbs/ft
(0.073 kN/m)
Single-net Erosion
Control Blankets &
Open Weave Textiles
3:1 (H:V) ≤0.15 @
3:1
1.5 lbs/ft2
(72 Pa)
50 lbs/ft
(0.73 kN/m)
Double-net Erosion
Control Blankets 2:1 (H:V) ≤0.20 @
2:1
1.75 lbs/ft2
(84 Pa)
75 lbs/ft
(1.09 kN/m)
Mulch Control Nets 5:1 (H:V) ≤0.10 @
5:1
0.25 lbs/ft2
(12 Pa)
25 lbs/ft
(0.36 kN/m) 24 months
Erosion Control
Blankets & Open
Weave Textiles
(slowly degrading)
1.5:1 (H:V) ≤0.25 @
1.5:1
2.00 lbs/ft2
(96 Pa)
100 lbs/ft
(1.45 kN/m) 24 months
Erosion Control
Blankets & Open
Weave Textiles
1:1 (H:V) ≤0.25 @
1:1
2.25 lbs/ft2
(108 Pa)
125 lbs/ft
(1.82 kN/m) 36 months
* C Factor and shear stress for mulch control nettings must be obtained with netting used in conjunction
with pre-applied mulch material. (See Section 5.3 of Chapter 7 Construction BMPs for more information
on the C Factor.)
1 Minimum Average Roll Values, Machine direction using ECTC Mod. ASTM D 5035.
2 C Factor calculated as ratio of soil loss from RECP protected slope (tested at specified or greater
gradient, H:V) to ratio of soil loss from unprotected (control) plot in large-scale testing.
3 Required minimum shear stress RECP (unvegetated) can sustain without physical damage or excess
erosion (> 12.7 mm (0.5 in) soil loss) during a 30-minute flow event in large-scale testing.
4 The permissible shear stress levels established for each performance category are based on historical
experience with products characterized by Manning's roughness coefficients in the range of 0.01 - 0.05.
5 Acceptable large-scale test methods may include ASTM D 6459, or other independent testing deemed
acceptable by the engineer.
6 Per the engineer’s discretion. Recommended acceptable large-scale testing protocol may include ASTM
D 6460, or other independent testing deemed acceptable by the engineer.
EC-6 Rolled Erosion Control Products (RECP)
RECP-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Table RECP-2. ECTC Standard Specification for Permanent1 Rolled Erosion Control Products
(Adapted from: Erosion Control Technology Council 2005)
Product Type Slope
Applications Channel Applications
TRMs with a minimum thickness of
0.25 inches (6.35 mm) per ASTM D
6525 and UV stability of 80% per
ASTM D 4355 (500 hours
exposure).
Maximum
Gradient
Maximum
Shear Stress4,5
Minimum
Tensile
Strength2,3
0.5:1 (H:V) 6.0 lbs/ft2 (288 Pa) 125 lbs/ft (1.82
kN/m)
0.5:1 (H:V) 8.0 lbs/ft2 (384 Pa) 150 lbs/ft (2.19
kN/m)
0.5:1 (H:V) 10.0 lbs/ft2 (480 Pa) 175 lbs/ft (2.55
kN/m)
1 For TRMs containing degradable components, all property values must be obtained on the non-
degradable portion of the matting alone.
2 Minimum Average Roll Values, machine direction only for tensile strength determination using ASTM
D 6818 (Supersedes Mod. ASTM D 5035 for RECPs)
3 Field conditions with high loading and/or high survivability requirements may warrant the use of a TRM
with a tensile strength of 44 kN/m (3,000 lb/ft) or greater.
4 Required minimum shear stress TRM (fully vegetated) can sustain without physical damage or excess
erosion (> 12.7 mm (0.5 in.) soil loss) during a 30-minute flow event in large scale testing.
5 Acceptable large-scale testing protocols may include ASTM D 6460, or other independent testing
deemed acceptable by the engineer.
Design and Installation
RECPs should be installed according to manufacturer’s specifications and guidelines. Regardless of the
type of product used, it is important to ensure no gaps or voids exist under the material and that all
corners of the material are secured using stakes and trenching. Continuous contact between the product
and the soil is necessary to avoid failure. Never use metal stakes to secure temporary erosion control
products. Often wooden stakes are used to anchor RECPs; however, wood stakes may present installation
and maintenance challenges and generally take a long time to biodegrade. Some local jurisdictions have
had favorable experiences using biodegradable stakes.
This BMP Fact Sheet provides design details for several commonly used ECB applications, including:
ECB-1 Pipe Outlet to Drainageway
ECB-2 Small Ditch or Drainageway
ECB-3 Outside of Drainageway
Rolled Erosion Control Products (RECP) EC-6
November 2010 Urban Drainage and Flood Control District RECP-5
Urban Storm Drainage Criteria Manual Volume 3
Staking patterns are also provided in the design details according to these factors:
ECB type
Slope or channel type
For other types of RECPs including TRMs, these design details are intended to serve as general
guidelines for design and installation; however, engineers should adhere to manufacturer’s installation
recommendations.
Maintenance and Removal
Inspection of erosion control blankets and other RECPs includes:
Check for general signs of erosion, including voids beneath the mat. If voids are apparent, fill the
void with suitable soil and replace the erosion control blanket, following the appropriate staking
pattern.
Check for damaged or loose stakes and secure loose portions of the blanket.
Erosion control blankets and other RECPs that are biodegradable typically do not need to be removed
after construction. If they must be removed, then an alternate soil stabilization method should be installed
promptly following removal.
Turf reinforcement mats, although generally resistant to biodegradation, are typically left in place as a
dense vegetated cover grows in through the mat matrix. The turf reinforcement mat provides long-term
stability and helps the established vegetation resist erosive forces.
EC-6 Rolled Erosion Control Products (RECP)
RECP-6 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Rolled Erosion Control Products (RECP) EC-6
November 2010 Urban Drainage and Flood Control District RECP-7
Urban Storm Drainage Criteria Manual Volume 3
EC-6 Rolled Erosion Control Products (RECP)
RECP-8 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Rolled Erosion Control Products (RECP) EC-6
November 2010 Urban Drainage and Flood Control District RECP-9
Urban Storm Drainage Criteria Manual Volume 3
Temporary Outlet Protection (TOP) EC-8
November 2010 Urban Drainage and Flood Control District TOP-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph TOP-1. Riprap outlet protection.
Description
Outlet protection helps to reduce erosion
immediately downstream of a pipe,
culvert, slope drain, rundown or other
conveyance with concentrated, high-
velocity flows. Typical outlet protection
consists of riprap or rock aprons at the
conveyance outlet.
Appropriate Uses
Outlet protection should be used when a
conveyance discharges onto a disturbed
area where there is potential for accelerated
erosion due to concentrated flow. Outlet
protection should be provided where the velocity at the culvert outlet exceeds the maximum permissible
velocity of the material in the receiving channel.
Note: This Fact Sheet and detail are for temporary outlet protection, outlets that are intended to be used
for less than 2 years. For permanent, long-term outlet protection, see the Major Drainage chapter of
Volume 1.
Design and Installation
Design outlet protection to handle runoff from the largest drainage area that may be contributing runoff
during construction (the drainage area may change as a result of grading). Key in rock, around the entire
perimeter of the apron, to a minimum depth of 6 inches for stability. Extend riprap to the height of the
culvert or the normal flow depth of the downstream channel, whichever is less. Additional erosion
control measures such as vegetative lining, turf reinforcement mat and/or other channel lining methods
may be required downstream of the outlet protection if the channel is susceptible to erosion. See Design
Detail OP-1 for additional information.
Maintenance and Removal
Inspect apron for damage and displaced rocks. If rocks are missing or significantly displaced, repair or
replace as necessary. If rocks are continuously missing or displaced, consider increasing the size of the
riprap or deeper keying of the perimeter.
Remove sediment accumulated at the outlet before the outlet protection becomes buried and ineffective.
When sediment accumulation is noted, check that upgradient BMPs, including inlet protection, are in
effective operating condition.
Outlet protection may be removed once the pipe is no longer
draining an upstream area, or once the downstream area has
been sufficiently stabilized. If the drainage pipe is
permanent, outlet protection can be left in place; however,
permanent outlet protection should be designed and
constructed in accordance with the requirements of the
Major Drainage chapter of Volume 2.
Outlet Protection
Functions
Erosion Control Yes
Sediment Control Moderate
Site/Material Management No
EC-8 Temporary Outlet Protection (TOP)
TOP-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Temporary Outlet Protection (TOP) EC-8
November 2010 Urban Drainage and Flood Control District TOP-3
Urban Storm Drainage Criteria Manual Volume 3
Earth Dikes and Drainage Swales (ED/DS) EC-10
November 2010 Urban Drainage and Flood Control District ED/DS-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph ED/DS-1. Example of an earth dike used to divert
flows at a construction site. Photo courtesy of CDOT.
Description
Earth dikes and drainage swales are
temporary storm conveyance channels
constructed either to divert runoff around
slopes or to convey runoff to additional
sediment control BMPs prior to discharge
of runoff from a site. Drainage swales
may be lined or unlined, but if an unlined
swale is used, it must be well compacted
and capable of resisting erosive velocities.
Appropriate Uses
Earth dikes and drainage swales are
typically used to control the flow path of
runoff at a construction site by diverting
runoff around areas prone to erosion, such
as steep slopes. Earth dikes and drainage
swales may also be constructed as
temporary conveyance features. This will
direct runoff to additional sediment control
treatment BMPs, such as sediment traps or
basins.
Design and Installation
When earth dikes are used to divert water for slope protection, the earth dike typically consists of a
horizontal ridge of soil placed perpendicular to the slope and angled slightly to provide drainage along the
contour. The dike is used in conjunction with a swale or a small channel upslope of the berm to convey
the diverted water. Temporary diversion dikes can be constructed by excavation of a V-shaped trench or
ditch and placement of the fill on the downslope side of the cut. There are two types of placement for
temporary slope diversion dikes:
A dike located at the top of a slope to divert upland runoff away from the disturbed area and convey it
in a temporary or permanent channel.
A diversion dike located at the base or mid-slope of a disturbed area to intercept runoff and reduce the
effective slope length.
Depending on the project, either an earth dike or drainage swale may be more appropriate. If there is a
need for cut on the project, then an excavated drainage
swale may be better suited. When the project is primarily
fill, then a conveyance constructed using a berm may be the
better option.
All dikes or swales receiving runoff from a disturbed
area should direct stormwater to a sediment control
BMP such as a sediment trap or basin.
Earth Dikes and Drainage Swales
Functions
Erosion Control Yes
Sediment Control Moderate
Site/Material Management No
EC-10 Earth Dikes and Drainage Swales (ED/DS)
ED/DS-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Unlined dikes or swales should only be used for intercepting sheet flow runoff and are not intended
for diversion of concentrated flows.
Details with notes are provided for several design variations, including:
ED-1. Unlined Earth Dike formed by Berm
DS-1. Unlined Excavated Swale
DS-2. Unlined Swale Formed by Cut and Fill
DS-3. ECB-lined Swale
DS-4. Synthetic-lined Swale
DS-5. Riprap-lined Swale
The details also include guidance on permissible velocities for cohesive channels if unlined approaches
will be used.
Maintenance and Removal
Inspect earth dikes for stability, compaction, and signs of erosion and repair. Inspect side slopes for
erosion and damage to erosion control fabric. Stabilize slopes and repair fabric as necessary. If there is
reoccurring extensive damage, consider installing rock check dams or lining the channel with riprap.
If drainage swales are not permanent, remove dikes and fill channels when the upstream area is stabilized.
Stabilize the fill or disturbed area immediately following removal by revegetation or other permanent
stabilization method approved by the local jurisdiction.
Earth Dikes and Drainage Swales (ED/DS) EC-10
November 2010 Urban Drainage and Flood Control District ED/DS-3
Urban Storm Drainage Criteria Manual Volume 3
EC-10 Earth Dikes and Drainage Swales (ED/DS)
ED/DS-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Earth Dikes and Drainage Swales (ED/DS) EC-10
November 2010 Urban Drainage and Flood Control District ED/DS-5
Urban Storm Drainage Criteria Manual Volume 3
Wind Erosion/Dust Control (DC) EC-14
November 2010 Urban Drainage and Flood Control District DC-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph DC-1. Water truck used for dust suppression. Photo
courtesy of Douglas County.
Description
Wind erosion and dust control BMPs
help to keep soil particles from entering
the air as a result of land disturbing
construction activities. These BMPs
include a variety of practices generally
focused on either graded disturbed areas
or construction roadways. For graded
areas, practices such as seeding and
mulching, use of soil binders, site
watering, or other practices that provide
prompt surface cover should be used.
For construction roadways, road
watering and stabilized surfaces should
be considered.
Appropriate Uses
Dust control measures should be used on any site where dust poses a problem to air quality. Dust control
is important to control for the health of construction workers and surrounding waterbodies.
Design and Installation
The following construction BMPs can be used for dust control:
An irrigation/sprinkler system can be used to wet the top layer of disturbed soil to help keep dry soil
particles from becoming airborne.
Seeding and mulching can be used to stabilize disturbed surfaces and reduce dust emissions.
Protecting existing vegetation can help to slow wind velocities across the ground surface, thereby
limiting the likelihood of soil particles to become airborne.
Spray-on soil binders form a bond between soil particles keeping them grounded. Chemical
treatments may require additional permitting requirements. Potential impacts to surrounding
waterways and habitat must be considered prior to use.
Placing rock on construction roadways and entrances will help keep dust to a minimum across the
construction site.
Wind fences can be installed on site to reduce wind
speeds. Install fences perpendicular to the prevailing
wind direction for maximum effectiveness.
Maintenance and Removal
When using an irrigation/sprinkler control system to aid in
dust control, be careful not to overwater. Overwatering will
cause construction vehicles to track mud off-site.
Wind Erosion Control/
Dust Control
Functions
Erosion Control Yes
Sediment Control No
Site/Material Management Moderate
Concrete Washout Area (CWA) MM-1
November 2010 Urban Drainage and Flood Control District CWA-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph CWA-1. Example of concrete washout area. Note gravel
tracking pad for access and sign.
Description
Concrete waste management involves
designating and properly managing a
specific area of the construction site as a
concrete washout area. A concrete
washout area can be created using one of
several approaches designed to receive
wash water from washing of tools and
concrete mixer chutes, liquid concrete
waste from dump trucks, mobile batch
mixers, or pump trucks. Three basic
approaches are available: excavation of a
pit in the ground, use of an above ground
storage area, or use of prefabricated haul-
away concrete washout containers.
Surface discharges of concrete washout
water from construction sites are prohibited.
Appropriate Uses
Concrete washout areas must be designated on all sites that will generate concrete wash water or liquid
concrete waste from onsite concrete mixing or concrete delivery.
Because pH is a pollutant of concern for washout activities, when unlined pits are used for concrete
washout, the soil must have adequate buffering capacity to result in protection of state groundwater
standards; otherwise, a liner/containment must be used. The following management practices are
recommended to prevent an impact from unlined pits to groundwater:
The use of the washout site should be temporary (less than 1 year), and
The washout site should be not be located in an area where shallow groundwater may be present, such
as near natural drainages, springs, or wetlands.
Design and Installation
Concrete washout activities must be conducted in a manner that does not contribute pollutants to surface
waters or stormwater runoff. Concrete washout areas may be lined or unlined excavated pits in the
ground, commercially manufactured prefabricated washout containers, or aboveground holding areas
constructed of berms, sandbags or straw bales with a plastic liner.
Although unlined washout areas may be used, lined pits may be required to protect groundwater under
certain conditions.
Do not locate an unlined washout area within 400 feet
of any natural drainage pathway or waterbody or
within 1,000 feet of any wells or drinking water
sources. Even for lined concrete washouts, it is
advisable to locate the facility away from waterbodies
and drainage paths. If site constraints make these
Concrete Washout Area
Functions
Erosion Control No
Sediment Control No
Site/Material Management Yes
MM-1 Concrete Washout Area (CWA)
CWA-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
setbacks infeasible or if highly permeable soils exist in the area, then the pit must be installed with an
impermeable liner (16 mil minimum thickness) or surface storage alternatives using prefabricated
concrete washout devices or a lined aboveground storage area should be used.
Design details with notes are provided in Detail CWA-1 for pits and CWA-2 for aboveground storage
areas. Pre-fabricated concrete washout container information can be obtained from vendors.
Maintenance and Removal
A key consideration for concrete washout areas is to ensure that adequate signage is in place identifying
the location of the washout area. Part of inspecting and maintaining washout areas is ensuring that
adequate signage is provided and in good repair and that the washout area is being used, as opposed to
washout in non-designated areas of the site.
Remove concrete waste in the washout area, as needed to maintain BMP function (typically when filled to
about two-thirds of its capacity). Collect concrete waste and deliver offsite to a designated disposal
location.
Upon termination of use of the washout site, accumulated solid waste, including concrete waste and any
contaminated soils, must be removed from the site to prevent on-site disposal of solid waste. If the wash
water is allowed to evaporate and the concrete hardens, it may be recycled.
Photograph CWA-3. Earthen concrete washout. Photo
courtesy of CDOT.
Photograph CWA-2. Prefabricated concrete washout. Photo
courtesy of CDOT.
Concrete Washout Area (CWA) MM-1
November 2010 Urban Drainage and Flood Control District CWA-3
Urban Storm Drainage Criteria Manual Volume 3
MM-1 Concrete Washout Area (CWA)
CWA-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Stockpile Management (SP) MM-2
November 2010 Urban Drainage and Flood Control District SP-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SP-1. A topsoil stockpile that has been partially
revegetated and is protected by silt fence perimeter control.
Description
Stockpile management includes
measures to minimize erosion and
sediment transport from soil stockpiles.
Appropriate Uses
Stockpile management should be used
when soils or other erodible materials
are stored at the construction site.
Special attention should be given to
stockpiles in close proximity to natural
or manmade storm systems.
Design and Installation
Locate stockpiles away from all drainage system components including storm sewer inlets. Where
practical, choose stockpile locations that that will remain undisturbed for the longest period of time as the
phases of construction progress. Place sediment control BMPs around the perimeter of the stockpile, such
as sediment control logs, rock socks, silt fence, straw bales and sand bags. See Detail SP-1 for guidance
on proper establishment of perimeter controls around a stockpile. For stockpiles in active use, provide a
stabilized designated access point on the upgradient side of the stockpile.
Stabilize the stockpile surface with surface roughening, temporary seeding and mulching, erosion control
blankets, or soil binders. Soils stockpiled for an extended period (typically for more than 60 days) should
be seeded and mulched with a temporary grass cover once the stockpile is placed (typically within 14
days). Use of mulch only or a soil binder is acceptable if the stockpile will be in place for a more limited
time period (typically 30-60 days). Timeframes for stabilization of stockpiles noted in this fact sheet are
"typical" guidelines. Check permit requirements for specific federal, state, and/or local requirements that
may be more prescriptive.
Stockpiles should not be placed in streets or paved areas unless no other practical alternative exists. See
the Stabilized Staging Area Fact Sheet for guidance when staging in roadways is unavoidable due to
space or right-of-way constraints. For paved areas, rock socks must be used for perimeter control and all
inlets with the potential to receive sediment from the stockpile (even from vehicle tracking) must be
protected.
Maintenance and Removal
Inspect perimeter controls and inlet protection in accordance with their respective BMP Fact Sheets.
Where seeding, mulch and/or soil binders are used, reseeding or reapplication of soil binder may be
necessary.
When temporary removal of a perimeter BMP is necessary
to access a stockpile, ensure BMPs are reinstalled in
accordance with their respective design detail section.
Stockpile Management
Functions
Erosion Control Yes
Sediment Control Yes
Site/Material Management Yes
MM-2 Stockpile Management (SM)
SP-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
When the stockpile is no longer needed, properly dispose of excess materials and revegetate or otherwise
stabilize the ground surface where the stockpile was located.
Stockpile Management (SP) MM-2
November 2010 Urban Drainage and Flood Control District SP-3
Urban Storm Drainage Criteria Manual Volume 3
MM-2 Stockpile Management (SM)
SP-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Stockpile Management (SP) MM-2
November 2010 Urban Drainage and Flood Control District SP-5
Urban Storm Drainage Criteria Manual Volume 3
MM-2 Stockpile Management (SM)
SP-6 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Good Housekeeping Practices (GH) MM-3
November 2010 Urban Drainage and Flood Control District GH-1
Urban Storm Drainage Criteria Manual Volume 3
Photographs GH-1 and GH-2. Proper materials
storage and secondary containment for fuel tanks
are important good housekeeping practices. Photos
courtesy of CDOT and City of Aurora.
Description
Implement construction site good housekeeping practices to
prevent pollution associated with solid, liquid and hazardous
construction-related materials and wastes. Stormwater
Management Plans (SWMPs) should clearly specify BMPs
including these good housekeeping practices:
Provide for waste management.
Establish proper building material staging areas.
Designate paint and concrete washout areas.
Establish proper equipment/vehicle fueling and
maintenance practices.
Control equipment/vehicle washing and allowable non-
stormwater discharges.
Develop a spill prevention and response plan.
Acknowledgement: This Fact Sheet is based directly on
EPA guidance provided in Developing Your Stormwater
Pollution Prevent Plan (EPA 2007).
Appropriate Uses
Good housekeeping practices are necessary at all construction sites.
Design and Installation
The following principles and actions should be addressed in SWMPs:
Provide for Waste Management. Implement management procedures and practices to prevent or
reduce the exposure and transport of pollutants in stormwater from solid, liquid and sanitary wastes
that will be generated at the site. Practices such as trash disposal, recycling, proper material handling,
and cleanup measures can reduce the potential for stormwater runoff to pick up construction site
wastes and discharge them to surface waters. Implement a comprehensive set of waste-management
practices for hazardous or toxic materials, such as paints, solvents, petroleum products, pesticides,
wood preservatives, acids, roofing tar, and other materials. Practices should include storage,
handling, inventory, and cleanup procedures, in case of spills. Specific practices that should be
considered include:
Solid or Construction Waste
o Designate trash and bulk waste-collection areas on-
site.
Good Housekeeping
Functions
Erosion Control No
Sediment Control No
Site/Material Management Yes
MM-3 Good Housekeeping Practices (GH)
GH-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Photograph GH-3. Locate portable toilet facilities on level
surfaces away from waterways and storm drains. Photo
courtesy of WWE.
o Recycle materials whenever possible (e.g., paper, wood, concrete, oil).
o Segregate and provide proper disposal options for hazardous material wastes.
o Clean up litter and debris from the construction site daily.
o Locate waste-collection areas away from streets, gutters, watercourses, and storm drains. Waste-
collection areas (dumpsters, and such) are often best located near construction site entrances to
minimize traffic on disturbed soils. Consider secondary containment around waste collection
areas to minimize the likelihood of contaminated discharges.
o Empty waste containers before they are full and overflowing.
Sanitary and Septic Waste
o Provide convenient, well-maintained, and properly located toilet facilities on-site.
o Locate toilet facilities away from storm drain inlets and waterways to prevent accidental spills
and contamination of stormwater.
o Maintain clean restroom facilities and empty portable toilets regularly.
o Where possible, provide secondary containment pans under portable toilets.
o Provide tie-downs or stake-downs for portable toilets.
o Educate employees, subcontractors, and suppliers on locations of facilities.
o Treat or dispose of sanitary and septic waste in accordance with state or local regulations. Do not
discharge or bury wastewater at the construction site.
o Inspect facilities for leaks. If found, repair or replace immediately.
o Special care is necessary during maintenance (pump out) to ensure that waste and/or biocide are
not spilled on the ground.
Hazardous Materials and Wastes
o Develop and implement employee and
subcontractor education, as needed, on
hazardous and toxic waste handling,
storage, disposal, and cleanup.
o Designate hazardous waste-collection
areas on-site.
o Place all hazardous and toxic material
wastes in secondary containment.
Good Housekeeping Practices (GH) MM-3
November 2010 Urban Drainage and Flood Control District GH-3
Urban Storm Drainage Criteria Manual Volume 3
o Hazardous waste containers should be inspected to ensure that all containers are labeled properly
and that no leaks are present.
Establish Proper Building Material Handling and Staging Areas. The SWMP should include
comprehensive handling and management procedures for building materials, especially those that are
hazardous or toxic. Paints, solvents, pesticides, fuels and oils, other hazardous materials or building
materials that have the potential to contaminate stormwater should be stored indoors or under cover
whenever possible or in areas with secondary containment. Secondary containment measures prevent
a spill from spreading across the site and may include dikes, berms, curbing, or other containment
methods. Secondary containment techniques should also ensure the protection of groundwater.
Designate staging areas for activities such as fueling vehicles, mixing paints, plaster, mortar, and
other potential pollutants. Designated staging areas enable easier monitoring of the use of materials
and clean up of spills. Training employees and subcontractors is essential to the success of this
pollution prevention principle. Consider the following specific materials handling and staging
practices:
o Train employees and subcontractors in proper handling and storage practices.
o Clearly designate site areas for staging and storage with signs and on construction drawings.
Staging areas should be located in areas central to the construction site. Segment the staging area
into sub-areas designated for vehicles, equipment, or stockpiles. Construction entrances and exits
should be clearly marked so that delivery vehicles enter/exit through stabilized areas with vehicle
tracking controls (See Vehicle Tracking Control Fact Sheet).
o Provide storage in accordance with Spill Protection, Control and Countermeasures (SPCC)
requirements and plans and provide cover and impermeable perimeter control, as necessary, for
hazardous materials and contaminated soils that must be stored on site.
o Ensure that storage containers are regularly inspected for leaks, corrosion, support or foundation
failure, or other signs of deterioration and tested for soundness.
o Reuse and recycle construction materials when possible.
Designate Concrete Washout Areas. Concrete contractors should be encouraged to use the washout
facilities at their own plants or dispatch facilities when feasible; however, concrete washout
commonly occurs on construction sites. If it is necessary to provide for concrete washout areas on-
site, designate specific washout areas and design facilities to handle anticipated washout water.
Washout areas should also be provided for paint and stucco operations. Because washout areas can
be a source of pollutants from leaks or spills, care must be taken with regard to their placement and
proper use. See the Concrete Washout Area Fact Sheet for detailed guidance.
Both self-constructed and prefabricated washout containers can fill up quickly when concrete, paint,
and stucco work are occurring on large portions of the site. Be sure to check for evidence that
contractors are using the washout areas and not dumping materials onto the ground or into drainage
facilities. If the washout areas are not being used regularly, consider posting additional signage,
relocating the facilities to more convenient locations, or providing training to workers and
contractors.
When concrete, paint, or stucco is part of the construction process, consider these practices which will
help prevent contamination of stormwater. Include the locations of these areas and the maintenance
and inspection procedures in the SWMP.
MM-3 Good Housekeeping Practices (GH)
GH-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
o Do not washout concrete trucks or equipment into storm drains, streets, gutters, uncontained
areas, or streams. Only use designated washout areas.
o Establish washout areas and advertise their locations with signs. Ensure that signage remains in
good repair.
o Provide adequate containment for the amount of wash water that will be used.
o Inspect washout structures daily to detect leaks or tears and to identify when materials need to be
removed.
o Dispose of materials properly. The preferred method is to allow the water to evaporate and to
recycle the hardened concrete. Full service companies may provide dewatering services and
should dispose of wastewater properly. Concrete wash water can be highly polluted. It should
not be discharged to any surface water, storm sewer system, or allowed to infiltrate into the
ground in the vicinity of waterbodies. Washwater should not be discharged to a sanitary sewer
system without first receiving written permission from the system operator.
Establish Proper Equipment/Vehicle Fueling and Maintenance Practices. Create a clearly
designated on-site fueling and maintenance area that is clean and dry. The on-site fueling area should
have a spill kit, and staff should know how to use it. If possible, conduct vehicle fueling and
maintenance activities in a covered area. Consider the following practices to help prevent the
discharge of pollutants to stormwater from equipment/vehicle fueling and maintenance. Include the
locations of designated fueling and maintenance areas and inspection and maintenance procedures in
the SWMP.
o Train employees and subcontractors in proper fueling procedures (stay with vehicles during
fueling, proper use of pumps, emergency shutoff valves, etc.).
o Inspect on-site vehicles and equipment regularly for leaks, equipment damage, and other service
problems.
o Clearly designate vehicle/equipment service areas away from drainage facilities and watercourses
to prevent stormwater run-on and runoff.
o Use drip pans, drip cloths, or absorbent pads when replacing spent fluids.
o Collect all spent fluids, store in appropriate labeled containers in the proper storage areas, and
recycle fluids whenever possible.
Control Equipment/Vehicle Washing and Allowable Non-Stormwater Discharges. Implement
practices to prevent contamination of surface and groundwater from equipment and vehicle wash
water. Representative practices include:
o Educate employees and subcontractors on proper washing procedures.
o Use off-site washing facilities, when available.
o Clearly mark the washing areas and inform workers that all washing must occur in this area.
o Contain wash water and treat it using BMPs. Infiltrate washwater when possible, but maintain
separation from drainage paths and waterbodies.
Good Housekeeping Practices (GH) MM-3
November 2010 Urban Drainage and Flood Control District GH-5
Urban Storm Drainage Criteria Manual Volume 3
o Use high-pressure water spray at vehicle washing facilities without detergents. Water alone can
remove most dirt adequately.
o Do not conduct other activities, such as vehicle repairs, in the wash area.
o Include the location of the washing facilities and the inspection and maintenance procedures in
the SWMP.
Develop a Spill Prevention and Response Plan. Spill prevention and response procedures must be
identified in the SWMP. Representative procedures include identifying ways to reduce the chance of
spills, stop the source of spills, contain and clean up spills, dispose of materials contaminated by
spills, and train personnel responsible for spill prevention and response. The plan should also specify
material handling procedures and storage requirements and ensure that clear and concise spill cleanup
procedures are provided and posted for areas in which spills may potentially occur. When developing
a spill prevention plan, include the following:
o Note the locations of chemical storage areas, storm drains, tributary drainage areas, surface
waterbodies on or near the site, and measures to stop spills from leaving the site.
o Provide proper handling and safety procedures for each type of waste. Keep Material Safety Data
Sheets (MSDSs) for chemical used on site with the SWMP.
o Establish an education program for employees and subcontractors on the potential hazards to
humans and the environment from spills and leaks.
o Specify how to notify appropriate authorities, such as police and fire departments, hospitals, or
municipal sewage treatment facilities to request assistance. Emergency procedures and contact
numbers should be provided in the SWMP and posted at storage locations.
o Describe the procedures, equipment and materials for immediate cleanup of spills and proper
disposal.
o Identify personnel responsible for implementing the plan in the event of a spill. Update the spill
prevention plan and clean up materials as changes occur to the types of chemicals stored and used
at the facility.
MM-3 Good Housekeeping Practices (GH)
GH-6 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Spill Prevention, Control, and Countermeasure (SPCC) Plan
Construction sites may be subject to 40 CFR Part 112 regulations that require the preparation and
implementation of a SPCC Plan to prevent oil spills from aboveground and underground storage tanks.
The facility is subject to this rule if it is a non-transportation-related facility that:
Has a total storage capacity greater than 1,320 gallons or a completely buried storage capacity
greater than 42,000 gallons.
Could reasonably be expected to discharge oil in quantities that may be harmful to navigable waters
of the United States and adjoining shorelines.
Furthermore, if the facility is subject to 40 CFR Part 112, the SWMP should reference the SPCC Plan.
To find out more about SPCC Plans, see EPA's website on SPPC at www.epa.gov/oilspill/spcc.htm.
Reporting Oil Spills
In the event of an oil spill, contact the National Response Center toll free at 1-800-424- 8802 for
assistance, or for more details, visit their website: www.nrc.uscg.mil.
Maintenance and Removal
Effective implementation of good housekeeping practices is dependent on clear designation of personnel
responsible for supervising and implementing good housekeeping programs, such as site cleanup and
disposal of trash and debris, hazardous material management and disposal, vehicle and equipment
maintenance, and other practices. Emergency response "drills" may aid in emergency preparedness.
Checklists may be helpful in good housekeeping efforts.
Staging and storage areas require permanent stabilization when the areas are no longer being used for
construction-related activities.
Construction-related materials, debris and waste must be removed from the construction site once
construction is complete.
Design Details
See the following Fact Sheets for related Design Details:
MM-1 Concrete Washout Area
MM-2 Stockpile Management
SM-4 Vehicle Tracking Control
Design details are not necessary for other good housekeeping practices; however, be sure to designate
where specific practices will occur on the appropriate construction drawings.
Silt Fence (SF) SC-1
November 2010 Urban Drainage and Flood Control District SF-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SF-1. Silt fence creates a sediment barrier, forcing
sheet flow runoff to evaporate or infiltrate.
Description
A silt fence is a woven geotextile fabric
attached to wooden posts and trenched
into the ground. It is designed as a
sediment barrier to intercept sheet flow
runoff from disturbed areas.
Appropriate Uses
A silt fence can be used where runoff is
conveyed from a disturbed area as sheet
flow. Silt fence is not designed to
receive concentrated flow or to be used
as a filter fabric. Typical uses include:
Down slope of a disturbed area to
accept sheet flow.
Along the perimeter of a receiving
water such as a stream, pond or
wetland.
At the perimeter of a construction site.
Design and Installation
Silt fence should be installed along the contour of slopes so that it intercepts sheet flow. The maximum
recommended tributary drainage area per 100 lineal feet of silt fence, installed along the contour, is
approximately 0.25 acres with a disturbed slope length of up to 150 feet and a tributary slope gradient no
steeper than 3:1. Longer and steeper slopes require additional measures. This recommendation only
applies to silt fence installed along the contour. Silt fence installed for other uses, such as perimeter
control, should be installed in a way that will not produce concentrated flows. For example, a "J-hook"
installation may be appropriate to force runoff to pond and evaporate or infiltrate in multiple areas rather
than concentrate and cause erosive conditions parallel to the silt fence.
See Detail SF-1 for proper silt fence installation, which involves proper trenching, staking, securing the
fabric to the stakes, and backfilling the silt fence. Properly installed silt fence should not be easily pulled
out by hand and there should be no gaps between the ground and the fabric.
Silt fence must meet the minimum allowable strength requirements, depth of installation requirement, and
other specifications in the design details. Improper installation
of silt fence is a common reason for silt fence failure; however,
when properly installed and used for the appropriate purposes, it
can be highly effective.
Silt Fence
Functions
Erosion Control No
Sediment Control Yes
Site/Material Management No
SC-1 Silt Fence (SF)
SF-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Photograph SF-2. When silt fence is not installed along
the contour, a "J-hook" installation may be appropriate
to ensure that the BMP does not create concentrated
flow parallel to the silt fence. Photo courtesy of Tom
Gore.
Maintenance and Removal
Inspection of silt fence includes observing the
material for tears or holes and checking for slumping
fence and undercut areas bypassing flows. Repair of
silt fence typically involves replacing the damaged
section with a new section. Sediment accumulated
behind silt fence should be removed, as needed to
maintain BMP effectiveness, typically before it
reaches a depth of 6 inches.
Silt fence may be removed when the upstream area
has reached final stabilization.
Silt Fence (SF) SC-1
November 2010 Urban Drainage and Flood Control District SF-3
Urban Storm Drainage Criteria Manual Volume 3
SC-1 Silt Fence (SF)
SF-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Sediment Control Log (SCL) SC-2
November 2015 Urban Drainage and Flood Control District SCL-1
Urban Storm Drainage Criteria Manual Volume 3
Photographs SCL-1 and SCL-2. Sediment control logs used as 1) a
perimeter control around a soil stockpile; and, 2) as a "J-hook"
perimeter control at the corner of a construction site.
Description
A sediment control log is a linear roll
made of natural materials such as
straw, coconut fiber, or compost. The
most common type of sediment control
log has straw filling and is often
referred to as a "straw wattle." All
sediment control logs are used as a
sediment barrier to intercept sheet flow
runoff from disturbed areas.
Appropriate Uses
Sediment control logs can be used in
the following applications to trap
sediment:
As perimeter control for stockpiles
and the site.
As part of inlet protection designs.
As check dams in small drainage
ditches. (Sediment control logs
are not intended for use in
channels with high flow
velocities.)
On disturbed slopes to shorten flow
lengths (as an erosion control).
As part of multi-layered perimeter control along a receiving water such as a stream, pond or wetland.
Sediment control logs work well in combination with other layers of erosion and sediment controls.
Design and Installation
Sediment control logs should be installed along the contour to avoid concentrating flows. The maximum
allowable tributary drainage area per 100 lineal feet of sediment control log, installed along the contour, is
approximately 0.25 acres with a disturbed slope length of up to 150 feet and a tributary slope gradient no
steeper than 3:1. Longer and steeper slopes require additional measures. This recommendation only
applies to sediment control logs installed along the contour. When installed for other uses, such as
perimeter control, it should be installed in a way that will not
produce concentrated flows. For example, a "J-hook"
installation may be appropriate to force runoff to pond and
evaporate or infiltrate in multiple areas rather than concentrate
and cause erosive conditions parallel to the BMP.
Sediment Control Log
Functions
Erosion Control Moderate
Sediment Control Yes
Site/Material Management No
SC-2 Sediment Control Log (SCL)
SCL-2 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Although sediment control logs initially allow runoff to flow through the BMP, they can quickly become
a barrier and should be installed as if they are impermeable.
Design details and notes for sediment control logs are provided in the following details. Sediment logs
must be properly installed per the detail to prevent undercutting, bypassing and displacement. When
installed on slopes, sediment control logs should be installed along the contours (i.e., perpendicular to
flow).
Improper installation can lead to poor performance. Be sure that sediment control logs are properly
trenched (if lighter than 8 lb/foot), anchored and tightly jointed.
Maintenance and Removal
Be aware that sediment control logs will eventually degrade. Remove accumulated sediment before the
depth is one-half the height of the sediment log and repair damage to the sediment log, typically by
replacing the damaged section.
Once the upstream area is stabilized, remove and properly dispose of the logs. Areas disturbed beneath
the logs may need to be seeded and mulched. Sediment control logs that are biodegradable may
occasionally be left in place (e.g., when logs are used in conjunction with erosion control blankets as
permanent slope breaks). However, removal of sediment control logs after final stabilization is typically
appropriate when used in perimeter control, inlet protection and check dam applications. Compost from
compost sediment control logs may be spread over the area and seeded as long as this does not cover
newly established vegetation.
Sediment Control Log (SCL) SC-2
November 2015 Urban Drainage and Flood Control District SCL-3
Urban Storm Drainage Criteria Manual Volume 3
SC-2 Sediment Control Log (SCL)
SCL-4 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Sediment Control Log (SCL) SC-2
November 2015 Urban Drainage and Flood Control District SCL-5
Urban Storm Drainage Criteria Manual Volume 3
SC-2 Sediment Control Log (SCL)
SCL-6 Urban Drainage and Flood Control District November 2015
Urban Storm Drainage Criteria Manual Volume 3
Straw Bale Barrier (SBB) SC-3
November 2010 Urban Drainage and Flood Control District SBB-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SBB-1. Straw bale barrier used for perimeter control.
Photo courtesy of Tom Gore.
Description
A straw bale barrier is a linear wall of
straw bales designed to intercept sheet
flow and trap sediment before runoff exits
a disturbed area.
Appropriate Uses
Appropriate uses of properly installed
straw bale barriers may include:
As a perimeter control for a site or soil
stockpile.
As a sediment control at the toe of an
erodible slope.
Along the edge of a stream or drainage
pathway to reduce sediment laden runoff from entering the waterway.
As part of an inlet protection design in sump conditions (See Inlet Protection BMP).
Do not use straw bale barriers in areas of concentrated flow or in areas where ponding is not desirable.
Straw bales tend to degrade quickly, so they should generally not be used in areas where longer term
disturbance is expected.
Due to a history of inappropriate placement, poor installation, and short effective lifespan, the use of
straw bales is discouraged or prohibited by some communities.
Design and Installation
The maximum recommended tributary drainage area per 100 lineal feet of straw bale barrier is 0.25 acres
with a disturbed slope length of up to 150 feet and a tributary slope gradient no steeper than 3:1; longer
and steeper slopes require additional measures. Design details with notes are provided in Detail SBB-1.
To be effective, bales must be installed in accordance with the design details with proper trenching,
staking, and binding. Jute and cotton string must not be used to bind the straw bale. The bales should be
certified weed-free prior to use.
Maintenance and Removal
Check bales for rotting and replace as necessary. Straw bales degrade, and rotting bales require
replacement on a regular basis (as often as every three months) depending on environmental conditions.
Check for undercutting, bypassed flows, and displacement.
Repair by properly re-installing the straw bale barrier and
repairing washouts around the bales. Remove sediment
accumulated behind the bale when it reaches one-quarter of
the bale height. Remove and properly dispose of the straw
bale once the upstream area has been stabilized. Areas of
disturbance beneath the bale should be seeded and mulched
when the bale is removed.
Straw Bale Barrier
Functions
Erosion Control No
Sediment Control Moderate
Site/Material Management No
SC-3 Straw Bale Barrier (SBB)
SBB-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Straw Bale Barrier (SBB) SC-3
November 2010 Urban Drainage and Flood Control District SBB-3
Urban Storm Drainage Criteria Manual Volume 3
Rock Sock (RS) SC-5
November 2010 Urban Drainage and Flood Control District RS-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph RS-1. Rock socks placed at regular intervals in a curb
line can help reduce sediment loading to storm sewer inlets. Rock
socks can also be used as perimeter controls.
Description
A rock sock is constructed of gravel
that has been wrapped by wire mesh or
a geotextile to form an elongated
cylindrical filter. Rock socks are
typically used either as a perimeter
control or as part of inlet protection.
When placed at angles in the curb line,
rock socks are typically referred to as
curb socks. Rock socks are intended to
trap sediment from stormwater runoff
that flows onto roadways as a result of
construction activities.
Appropriate Uses
Rock socks can be used at the perimeter
of a disturbed area to control localized
sediment loading. A benefit of rock
socks as opposed to other perimeter controls is that they do not have to be trenched or staked into the
ground; therefore, they are often used on roadway construction projects where paved surfaces are present.
Use rock socks in inlet protection applications when the construction of a roadway is substantially
complete and the roadway has been directly connected to a receiving storm system.
Design and Installation
When rock socks are used as perimeter controls, the maximum recommended tributary drainage area per
100 lineal feet of rock socks is approximately 0.25 acres with disturbed slope length of up to 150 feet and
a tributary slope gradient no steeper than 3:1. A rock sock design detail and notes are provided in Detail
RS-1. Also see the Inlet Protection Fact Sheet for design and installation guidance when rock socks are
used for inlet protection and in the curb line.
When placed in the gutter adjacent to a curb, rock socks should protrude no more than two feet from the
curb in order for traffic to pass safely. If located in a high traffic area, place construction markers to alert
drivers and street maintenance workers of their presence.
Maintenance and Removal
Rock socks are susceptible to displacement and breaking due to vehicle traffic. Inspect rock socks for
damage and repair or replace as necessary. Remove sediment by sweeping or vacuuming as needed to
maintain the functionality of the BMP, typically when sediment
has accumulated behind the rock sock to one-half of the sock's
height.
Once upstream stabilization is complete, rock socks and
accumulated sediment should be removed and properly disposed.
Rock Sock
Functions
Erosion Control No
Sediment Control Yes
Site/Material Management No
SC-5 Rock Sock (RS)
RS-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Rock Sock (RS) SC-5
November 2010 Urban Drainage and Flood Control District RS-3
Urban Storm Drainage Criteria Manual Volume 3
Inlet Protection (IP) SC-6
August 2013 Urban Drainage and Flood Control District IP-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph IP-1. Inlet protection for a curb opening inlet.
Description
Inlet protection consists of permeable
barriers installed around an inlet to
filter runoff and remove sediment prior
to entering a storm drain inlet. Inlet
protection can be constructed from rock
socks, sediment control logs, silt fence,
block and rock socks, or other materials
approved by the local jurisdiction.
Area inlets can also be protected by
over-excavating around the inlet to
form a sediment trap.
Appropriate Uses
Install protection at storm sewer inlets
that are operable during construction.
Consider the potential for tracked-out
sediment or temporary stockpile areas to contribute sediment to inlets when determining which inlets
must be protected. This may include inlets in the general proximity of the construction area, not limited
to downgradient inlets. Inlet protection is not a stand-alone BMP and should be used in conjunction with
other upgradient BMPs.
Design and Installation
To function effectively, inlet protection measures must be installed to ensure that flows do not bypass the
inlet protection and enter the storm drain without treatment. However, designs must also enable the inlet
to function without completely blocking flows into the inlet in a manner that causes localized flooding.
When selecting the type of inlet protection, consider factors such as type of inlet (e.g., curb or area, sump
or on-grade conditions), traffic, anticipated flows, ability to secure the BMP properly, safety and other
site-specific conditions. For example, block and rock socks will be better suited to a curb and gutter
along a roadway, as opposed to silt fence or sediment control logs, which cannot be properly secured in a
curb and gutter setting, but are effective area inlet protection measures.
Several inlet protection designs are provided in the Design Details. Additionally, a variety of proprietary
products are available for inlet protection that may be approved for use by local governments. If
proprietary products are used, design details and installation procedures from the manufacturer must be
followed. Regardless of the type of inlet protection selected, inlet protection is most effective when
combined with other BMPs such as curb socks and check dams. Inlet protection is often the last barrier
before runoff enters the storm sewer or receiving water.
Design details with notes are provided for these forms of inlet
protection:
IP-1. Block and Rock Sock Inlet Protection for Sump or On-grade
Inlets
IP-2. Curb (Rock) Socks Upstream of Inlet Protection, On-grade
Inlets
Inlet Protection
(various forms)
Functions
Erosion Control No
Sediment Control Yes
Site/Material Management No
SC-6 Inlet Protection (IP)
IP-2 Urban Drainage and Flood Control District August 2013
Urban Storm Drainage Criteria Manual Volume 3
IP-3. Rock Sock Inlet Protection for Sump/Area Inlet
IP-4. Silt Fence Inlet Protection for Sump/Area Inlet
IP-5. Over-excavation Inlet Protection
IP-6. Straw Bale Inlet Protection for Sump/Area Inlet
CIP-1. Culvert Inlet Protection
Propriety inlet protection devices should be installed in accordance with manufacturer specifications.
More information is provided below on selecting inlet protection for sump and on-grade locations.
Inlets Located in a Sump
When applying inlet protection in sump conditions, it is important that the inlet continue to function
during larger runoff events. For curb inlets, the maximum height of the protective barrier should be lower
than the top of the curb opening to allow overflow into the inlet during larger storms without excessive
localized flooding. If the inlet protection height is greater than the curb elevation, particularly if the filter
becomes clogged with sediment, runoff will not enter the inlet and may bypass it, possibly causing
localized flooding, public safety issues, and downstream erosion and damage from bypassed flows.
Area inlets located in a sump setting can be protected through the use of silt fence, concrete block and
rock socks (on paved surfaces), sediment control logs/straw wattles embedded in the adjacent soil and
stacked around the area inlet (on pervious surfaces), over-excavation around the inlet, and proprietary
products providing equivalent functions.
Inlets Located on a Slope
For curb and gutter inlets on paved sloping streets, block and rock sock inlet protection is recommended
in conjunction with curb socks in the gutter leading to the inlet. For inlets located along unpaved roads,
also see the Check Dam Fact Sheet.
Maintenance and Removal
Inspect inlet protection frequently. Inspection and maintenance guidance includes:
Inspect for tears that can result in sediment directly entering the inlet, as well as result in the contents
of the BMP (e.g., gravel) washing into the inlet.
Check for improper installation resulting in untreated flows bypassing the BMP and directly entering
the inlet or bypassing to an unprotected downstream inlet. For example, silt fence that has not been
properly trenched around the inlet can result in flows under the silt fence and directly into the inlet.
Look for displaced BMPs that are no longer protecting the inlet. Displacement may occur following
larger storm events that wash away or reposition the inlet protection. Traffic or equipment may also
crush or displace the BMP.
Monitor sediment accumulation upgradient of the inlet protection.
Inlet Protection (IP) SC-6
August 2013 Urban Drainage and Flood Control District IP-3
Urban Storm Drainage Criteria Manual Volume 3
Remove sediment accumulation from the area upstream of the inlet protection, as needed to maintain
BMP effectiveness, typically when it reaches no more than half the storage capacity of the inlet
protection. For silt fence, remove sediment when it accumulates to a depth of no more than 6 inches.
Remove sediment accumulation from the area upstream of the inlet protection as needed to maintain
the functionality of the BMP.
Propriety inlet protection devices should be inspected and maintained in accordance with
manufacturer specifications. If proprietary inlet insert devices are used, sediment should be removed
in a timely manner to prevent devices from breaking and spilling sediment into the storm drain.
Inlet protection must be removed and properly disposed of when the drainage area for the inlet has
reached final stabilization.
SC-6 Inlet Protection (IP)
IP-4 Urban Drainage and Flood Control District August 2013
Urban Storm Drainage Criteria Manual Volume 3
Inlet Protection (IP) SC-6
August 2013 Urban Drainage and Flood Control District IP-5
Urban Storm Drainage Criteria Manual Volume 3
SC-6 Inlet Protection (IP)
IP-6 Urban Drainage and Flood Control District August 2013
Urban Storm Drainage Criteria Manual Volume 3
Inlet Protection (IP) SC-6
August 2013 Urban Drainage and Flood Control District IP-7
Urban Storm Drainage Criteria Manual Volume 3
SC-6 Inlet Protection (IP)
IP-8 Urban Drainage and Flood Control District August 2013
Urban Storm Drainage Criteria Manual Volume 3
Construction Phasing/Sequencing (CP) SM-1
November 2010 Urban Drainage and Flood Control District CP-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph CP-1. Construction phasing to avoid disturbing the
entire area at one time. Photo courtesy of WWE.
Description
Effective construction site management
to minimize erosion and sediment
transport includes attention to
construction phasing, scheduling, and
sequencing of land disturbing activities.
On most construction projects, erosion
and sediment controls will need to be
adjusted as the project progresses and
should be documented in the SWMP.
Construction phasing refers to
disturbing only part of a site at a time to
limit the potential for erosion from
dormant parts of a site. Grading
activities and construction are completed
and soils are effectively stabilized on one
part of a site before grading and
construction begins on another portion of the site.
Construction sequencing or scheduling refers to a specified work schedule that coordinates the timing of
land disturbing activities and the installation of erosion and sediment control practices.
Appropriate Uses
All construction projects can benefit from upfront planning to phase and sequence construction activities
to minimize the extent and duration of disturbance. Larger projects and linear construction projects may
benefit most from construction sequencing or phasing, but even small projects can benefit from
construction sequencing that minimizes the duration of disturbance.
Typically, erosion and sediment controls needed at a site will change as a site progresses through the
major phases of construction. Erosion and sediment control practices corresponding to each phase of
construction must be documented in the SWMP.
Design and Installation
BMPs appropriate to the major phases of development should be identified on construction drawings. In
some cases, it will be necessary to provide several drawings showing construction-phase BMPs placed
according to stages of development (e.g., clearing and grading, utility installation, active construction,
final stabilization). Some municipalities in the Denver area set maximum sizes for disturbed area
associated with phases of a construction project. Additionally, requirements for phased construction
drawings vary among local governments within the UDFCD boundary. Some local governments require
separate erosion and sediment control drawings for initial
BMPs, interim conditions (in active construction), and final
stabilization.
Construction Scheduling
Functions
Erosion Control Moderate
Sediment Control Moderate
Site/Material Management Yes
SM-1 Construction Phasing/Sequencing (CP)
CP-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Typical construction phasing BMPs include:
Limit the amount of disturbed area at any given time on a site to the extent practical. For example, a
100-acre subdivision might be constructed in five phases of 20 acres each.
If there is carryover of stockpiled material from one phase to the next, position carryover material in a
location easily accessible for the pending phase that will not require disturbance of stabilized areas to
access the stockpile. Particularly with regard to efforts to balance cut and fill at a site, careful
planning for location of stockpiles is important.
Typical construction sequencing BMPs include:
Sequence construction activities to minimize duration of soil disturbance and exposure. For example,
when multiple utilities will occupy the same trench, schedule installation so that the trench does not
have to be closed and opened multiple times.
Schedule site stabilization activities (e.g., landscaping, seeding and mulching, installation of erosion
control blankets) as soon as feasible following grading.
Install initial erosion and sediment control practices before construction begins. Promptly install
additional BMPs for inlet protection, stabilization, etc., as construction activities are completed.
Table CP-1 provides typical sequencing of construction activities and associated BMPs.
Maintenance and Removal
When the construction schedule is altered, erosion and sediment control measures in the SWMP and
construction drawings should be appropriately adjusted to reflect actual "on the ground" conditions at the
construction site. Be aware that changes in construction schedules can have significant implications for
site stabilization, particularly with regard to establishment of vegetative cover.
Construction Phasing/Sequencing (CP) SM-1
November 2010 Urban Drainage and Flood Control District CP-3
Urban Storm Drainage Criteria Manual Volume 3
Table CP -1. Typical Phased BMP Installation for Construction Projects
Project
Phase BMPs
Pre-
disturbance,
Site Access
Install sediment controls downgradient of access point (on paved streets this may consist
of inlet protection).
Establish vehicle tracking control at entrances to paved streets. Fence as needed.
Use construction fencing to define the boundaries of the project and limit access to areas of
the site that are not to be disturbed.
Note: it may be necessary to protect inlets in the general vicinity of the site, even if not
downgradient, if there is a possibility that sediment tracked from the site could contribute
to the inlets.
Site Clearing
and Grubbing
Install perimeter controls as needed on downgradient perimeter of site (silt fence, wattles,
etc).
Limit disturbance to those areas planned for disturbance and protect undisturbed areas
within the site (construction fence, flagging, etc).
Preserve vegetative buffer at site perimeter.
Create stabilized staging area.
Locate portable toilets on flat surfaces away from drainage paths. Stake in areas
susceptible to high winds.
Construct concrete washout area and provide signage.
Establish waste disposal areas.
Install sediment basins.
Create dirt perimeter berms and/or brush barriers during grubbing and clearing.
Separate and stockpile topsoil, leave roughened and/or cover.
Protect stockpiles with perimeter control BMPs. Stockpiles should be located away from
drainage paths and should be accessed from the upgradient side so that perimeter controls
can remain in place on the downgradient side. Use erosion control blankets, temporary
seeding, and/or mulch for stockpiles that will be inactive for an extended period.
Leave disturbed area of site in a roughened condition to limit erosion. Consider temporary
revegetation for areas of the site that have been disturbed but that will be inactive for an
extended period.
Water to minimize dust but not to the point that watering creates runoff.
SM-1 Construction Phasing/Sequencing (CP)
CP-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Project
Phase BMPs
Utility And
Infrastructure
Installation
In Addition to the Above BMPs:
Close trench as soon as possible (generally at the end of the day).
Use rough-cut street control or apply road base for streets that will not be promptly paved.
Provide inlet protection as streets are paved and inlets are constructed.
Protect and repair BMPs, as necessary.
Perform street sweeping as needed.
Building
Construction
In Addition to the Above BMPs:
Implement materials management and good housekeeping practices for home building
activities.
Use perimeter controls for temporary stockpiles from foundation excavations.
For lots adjacent to streets, lot-line perimeter controls may be necessary at the back of
curb.
Final Grading
In Addition to the Above BMPs:
Remove excess or waste materials.
Remove stored materials.
Final
Stabilization
In Addition to the Above BMPs:
Seed and mulch/tackify.
Seed and install blankets on steep slopes.
Remove all temporary BMPs when site has reached final stabilization.
Protection of Existing Vegetation (PV) SM-2
November 2010 Urban Drainage and Flood Control District PV-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph PV-1. Protection of existing vegetation and a sensitive
area. Photo courtesy of CDOT.
Description
Protection of existing vegetation on a
construction site can be accomplished
through installation of a construction
fence around the area requiring protection.
In cases where upgradient areas are
disturbed, it may also be necessary to
install perimeter controls to minimize
sediment loading to sensitive areas such as
wetlands. Existing vegetation may be
designated for protection to maintain a
stable surface cover as part of construction
phasing, or vegetation may be protected in
areas designated to remain in natural
condition under post-development
conditions (e.g., wetlands, mature trees,
riparian areas, open space).
Appropriate Uses
Existing vegetation should be preserved for the maximum practical duration on a construction site
through the use of effective construction phasing. Preserving vegetation helps to minimize erosion and
can reduce revegetation costs following construction.
Protection of wetland areas is required under the Clean Water Act, unless a permit has been obtained from
the U.S. Army Corps of Engineers (USACE) allowing impacts in limited areas.
If trees are to be protected as part of post-development landscaping, care must be taken to avoid several
types of damage, some of which may not be apparent at the time of injury. Potential sources of injury
include soil compaction during grading or due to construction traffic, direct equipment-related injury such
as bark removal, branch breakage, surface grading and trenching, and soil cut and fill. In order to
minimize injuries that may lead to immediate or later death of the tree, tree protection zones should be
developed during site design, implemented at the beginning of a construction project, as well as continued
during active construction.
Design and Installation
General
Once an area has been designated as a preservation area, there should be no construction activity allowed
within a set distance of the area. Clearly mark the area with construction fencing. Do not allow
stockpiles, equipment, trailers or parking within the
protected area. Guidelines to protect various types of
existing vegetation follow.
Protection of Existing Vegetation
Functions
Erosion Control Yes
Sediment Control Moderate
Site/Material Management Yes
SM-2 Protection of Existing Vegetation (PV)
PV-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Surface Cover During Phased Construction
Install construction fencing or other perimeter controls around areas to be protected from clearing and
grading as part of construction phasing.
Maintaining surface cover on steep slopes for the maximum practical duration during construction is
recommended.
Open Space Preservation
Where natural open space areas will be preserved as part of a development, it is important to install
construction fencing around these areas to protect them from compaction. This is particularly important
when areas with soils with high infiltration rates are preserved as part of LID designs. Preserved open
space areas should not be used for staging and equipment storage.
Wetlands and Riparian Areas
Install a construction fence around the perimeter of the wetland or riparian (streamside vegetation) area to
prevent access by equipment. In areas downgradient of disturbed areas, install a perimeter control such as
silt fence, sediment control logs, or similar measure to minimize sediment loading to the wetland.
Tree Protection 1
Before beginning construction operations, establish a tree protection zone around trees to be
preserved by installing construction fences. Allow enough space from the trunk to protect the root
zone from soil compaction and mechanical damage, and the branches from mechanical damage (see
Table PV-1). If low branches will be kept, place the fence outside of the drip line. Where this is not
possible, place fencing as far away from the trunk as possible. In order to maintain a healthy tree, be
aware that about 60 percent of the tree's root zone extends beyond the drip line.
Table PV-1
Guidelines for Determining the Tree Protection Zone
(Source: Matheny and Clark, 1998; as cited in GreenCO and WWE 2008)
Distance from Trunk (ft) per inch of DBH
Species Tolerance to Damage Young Mature Over mature
Good 0.5' 0.75' 1.0'
Moderate 0.75' 1.0' 1.25'
Poor 1.0' 1.25' 1.5'
Notes: DBH = diameter at breast height (4.5 ft above grade); Young = <20% of
life expectancy; Mature = 20%-80% of life expectancy; Over mature =>80% of
life expectancy
Most tree roots grow within the top 12 to 18 inches of soil. Grade changes within the tree protection
zone should be avoided where possible because seemingly minor grade changes can either smother
1 Tree Protection guidelines adapted from GreenCO and WWE (2008). Green Industry Best Management Practices (BMPs) for
the Conservation and Protection of Water Resources in Colorado: Moving Toward Sustainability, Third Release. See
www.greenco.org for more detailed guidance on tree preservation.
Protection of Existing Vegetation (PV) SM-2
November 2010 Urban Drainage and Flood Control District PV-3
Urban Storm Drainage Criteria Manual Volume 3
roots (in fill situations) or damage roots (in cut situations). Consider small walls where needed to
avoid grade changes in the tree protection zone.
Place and maintain a layer of mulch 4 to 6-inch thick from the tree trunk to the fencing, keeping a
6-inch space between the mulch and the trunk. Mulch helps to preserve moisture and decrease soil
compaction if construction traffic is unavoidable. When planting operations are completed, the mulch
may be reused throughout planting areas.
Limit access, if needed at all, and appoint one route as the main entrance and exit to the tree
protection zone. Within the tree protection zone, do not allow any equipment to be stored, chemicals
to be dumped, or construction activities to take place except fine grading, irrigation system
installation, and planting operations. These activities should be conducted in consultation with a
landscaping professional, following Green Industry BMPs.
Be aware that soil compaction can cause extreme damage to tree health that may appear gradually
over a period of years. Soil compaction is easier to prevent than repair.
Maintenance and Removal
Repair or replace damaged or displaced fencing or other protective barriers around the vegetated area.
If damage occurs to a tree, consult an arborist for guidance on how to care for the tree. If a tree in a
designated preservation area is damaged beyond repair, remove and replace with a 2-inch diameter tree of
the same or similar species.
Construction equipment must not enter a wetland area, except as permitted by the U.S. Army Corps of
Engineers (USACE). Inadvertent placement of fill in a wetland is a 404 permit violation and will require
notification of the USACE.
If damage to vegetation occurs in a protected area, reseed the area with the same or similar species,
following the recommendations in the USDCM Revegetation chapter.
Construction Fence (CF) SM-3
November 2010 Urban Drainage and Flood Control District CF-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph CF-1. A construction fence helps delineate areas where
existing vegetation is being protected. Photo courtesy of Douglas
County.
Description
A construction fence restricts site access
to designated entrances and exits,
delineates construction site boundaries,
and keeps construction out of sensitive
areas such as natural areas to be
preserved as open space, wetlands and
riparian areas.
Appropriate Uses
A construction fence can be used to
delineate the site perimeter and locations
within the site where access is restricted
to protect natural resources such as
wetlands, waterbodies, trees, and other
natural areas of the site that should not be
disturbed.
If natural resource protection is an objective, then the construction fencing should be used in combination
with other perimeter control BMPs such as silt fence, sediment control logs or similar measures.
Design and Installation
Construction fencing may be chain link or plastic mesh and should be installed following manufacturer’s
recommendations. See Detail CF-1 for typical installations.
Do not place construction fencing in areas within work limits of machinery.
Maintenance and Removal
Inspect fences for damage; repair or replace as necessary.
Fencing should be tight and any areas with slumping or fallen posts should be reinstalled.
Fencing should be removed once construction is complete.
Construction Fence
Functions
Erosion Control No
Sediment Control No
Site/Material Management Yes
SM-3 Construction Fence (CF)
CF-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Construction Fence (CF) SM-3
November 2010 Urban Drainage and Flood Control District CF-3
Urban Storm Drainage Criteria Manual Volume 3
Vehicle Tracking Control (VTC) SM-4
November 2010 Urban Drainage and Flood Control District VTC-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph VTC-1. A vehicle tracking control pad constructed with
properly sized rock reduces off-site sediment tracking.
Description
Vehicle tracking controls provide
stabilized construction site access where
vehicles exit the site onto paved public
roads. An effective vehicle tracking
control helps remove sediment (mud or
dirt) from vehicles, reducing tracking onto
the paved surface.
Appropriate Uses
Implement a stabilized construction
entrance or vehicle tracking control where
frequent heavy vehicle traffic exits the
construction site onto a paved roadway. An
effective vehicle tracking control is
particularly important during the following conditions:
Wet weather periods when mud is easily tracked off site.
During dry weather periods where dust is a concern.
When poorly drained, clayey soils are present on site.
Although wheel washes are not required in designs of vehicle tracking controls, they may be needed at
particularly muddy sites.
Design and Installation
Construct the vehicle tracking control on a level surface. Where feasible, grade the tracking control
towards the construction site to reduce off-site runoff. Place signage, as needed, to direct construction
vehicles to the designated exit through the vehicle tracking control. There are several different types of
stabilized construction entrances including:
VTC-1. Aggregate Vehicle Tracking Control. This is a coarse-aggregate surfaced pad underlain by a
geotextile. This is the most common vehicle tracking control, and when properly maintained can be
effective at removing sediment from vehicle tires.
VTC-2. Vehicle Tracking Control with Construction Mat or Turf Reinforcement Mat. This type of
control may be appropriate for site access at very small construction sites with low traffic volume over
vegetated areas. Although this application does not typically remove sediment from vehicles, it helps
protect existing vegetation and provides a stabilized entrance.
Vehicle Tracking Control
Functions
Erosion Control Moderate
Sediment Control Yes
Site/Material Management Yes
SM-4 Vehicle Tracking Control (VTC)
VTC-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Photograph VTC-2. A vehicle tracking control pad with wheel wash
facility. Photo courtesy of Tom Gore.
VTC-3. Stabilized Construction Entrance/Exit with Wheel Wash. This is an aggregate pad, similar
to VTC-1, but includes equipment for tire washing. The wheel wash equipment may be as simple as
hand-held power washing equipment to more advance proprietary systems. When a wheel wash is
provided, it is important to direct wash water to a sediment trap prior to discharge from the site.
Vehicle tracking controls are sometimes installed in combination with a sediment trap to treat runoff.
Maintenance and Removal
Inspect the area for degradation and
replace aggregate or material used for a
stabilized entrance/exit as needed. If the
area becomes clogged and ponds water,
remove and dispose of excess sediment
or replace material with a fresh layer of
aggregate as necessary.
With aggregate vehicle tracking controls,
ensure rock and debris from this area do
not enter the public right-of-way.
Remove sediment that is tracked onto the
public right of way daily or more
frequently as needed. Excess sediment
in the roadway indicates that the
stabilized construction entrance needs
maintenance.
Ensure that drainage ditches at the
entrance/exit area remain clear.
A stabilized entrance should be removed only when there is no longer the potential for vehicle tracking to
occur. This is typically after the site has been stabilized.
When wheel wash equipment is used, be sure that the wash water is discharged to a sediment trap prior to
discharge. Also inspect channels conveying the water from the wash area to the sediment trap and
stabilize areas that may be eroding.
When a construction entrance/exit is removed, excess sediment from the aggregate should be removed
and disposed of appropriately. The entrance should be promptly stabilized with a permanent surface
following removal, typically by paving.
Vehicle Tracking Control (VTC) SM-4
November 2010 Urban Drainage and Flood Control District VTC-3
Urban Storm Drainage Criteria Manual Volume 3
SM-4 Vehicle Tracking Control (VTC)
VTC-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Vehicle Tracking Control (VTC) SM-4
November 2010 Urban Drainage and Flood Control District VTC-5
Urban Storm Drainage Criteria Manual Volume 3
SM-4 Vehicle Tracking Control (VTC)
VTC-6 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Stabilized Construction Roadway (SCR) SM-5
November 2010 Urban Drainage and Flood Control District SCR-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SCR-1. Stabilized construction roadway.
Description
A stabilized construction roadway is a
temporary method to control sediment
runoff, vehicle tracking, and dust from
roads during construction activities.
Appropriate Uses
Use on high traffic construction roads to
minimize dust and erosion.
Stabilized construction roadways are
used instead of rough-cut street controls
on roadways with frequent construction
traffic.
Design and Installation
Stabilized construction roadways typically involve two key components: 1) stabilizing the road surface
with an aggregate base course of 3-inch-diameter granular material and 2) stabilizing roadside ditches, if
applicable. Early application of road base is generally suitable where a layer of coarse aggregate is
specified for final road construction.
Maintenance and Removal
Apply additional gravel as necessary to ensure roadway integrity.
Inspect drainage ditches along the roadway for erosion and stabilize, as needed, through the use of check
dams or rolled erosion control products.
Gravel may be removed once the road is ready to be paved. Prior to paving, the road should be inspected
for grade changes and damage. Regrade and repair as necessary.
Stabilized Construction Roadway
Functions
Erosion Control Yes
Sediment Control Moderate
Site/Material Management Yes
Stabilized Staging Area (SSA) SM-6
November 2010 Urban Drainage and Flood Control District SSA-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SSA-1. Example of a staging area with a gravel surface to
prevent mud tracking and reduce runoff. Photo courtesy of Douglas
County.
Description
A stabilized staging area is a clearly
designated area where construction
equipment and vehicles, stockpiles, waste
bins, and other construction-related
materials are stored. The contractor
office trailer may also be located in this
area. Depending on the size of the
construction site, more than one staging
area may be necessary.
Appropriate Uses
Most construction sites will require a
staging area, which should be clearly
designated in SWMP drawings. The layout
of the staging area may vary depending on
the type of construction activity. Staging areas located in roadways due to space constraints require
special measures to avoid materials being washed into storm inlets.
Design and Installation
Stabilized staging areas should be completed prior to other construction activities beginning on the site.
Major components of a stabilized staging area include:
Appropriate space to contain storage and provide for loading/unloading operations, as well as parking
if necessary.
A stabilized surface, either paved or covered, with 3-inch diameter aggregate or larger.
Perimeter controls such as silt fence, sediment control logs, or other measures.
Construction fencing to prevent unauthorized access to construction materials.
Provisions for Good Housekeeping practices related to materials storage and disposal, as described in
the Good Housekeeping BMP Fact Sheet.
A stabilized construction entrance/exit, as described in the Vehicle Tracking Control BMP Fact Sheet,
to accommodate traffic associated with material delivery and waste disposal vehicles.
Over -sizing the stabilized staging area may result in disturbance of existing vegetation in excess of that
required for the project. This increases costs, as well as
requirements for long-term stabilization following the
construction period. When designing the stabilized staging area,
minimize the area of disturbance to the extent practical.
Stabilized Staging Area
Functions
Erosion Control Yes
Sediment Control Moderate
Site/Material
Yes
SM-6 Stabilized Staging Area (SSA)
SSA-2 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
See Detail SSA-1 for a typical stabilized staging area and SSA-2 for a stabilized staging area when
materials staging in roadways is required.
Maintenance and Removal
Maintenance of stabilized staging areas includes maintaining a stable surface cover of gravel, repairing
perimeter controls, and following good housekeeping practices.
When construction is complete, debris, unused stockpiles and materials should be recycled or properly
disposed. In some cases, this will require disposal of contaminated soil from equipment leaks in an
appropriate landfill. Staging areas should then be permanently stabilized with vegetation or other surface
cover planned for the development.
Minimizing Long-Term Stabilization Requirements
Utilize off-site parking and restrict vehicle access to the site.
Use construction mats in lieu of rock when staging is provided in an area that will not be disturbed
otherwise.
Consider use of a bermed contained area for materials and equipment that do not require a
stabilized surface.
Consider phasing of staging areas to avoid disturbance in an area that will not be otherwise
disturbed.
Stabilized Staging Area (SSA) SM-6
November 2010 Urban Drainage and Flood Control District SSA-3
Urban Storm Drainage Criteria Manual Volume 3
SM-6 Stabilized Staging Area (SSA)
SSA-4 Urban Drainage and Flood Control District November 2010
Urban Storm Drainage Criteria Manual Volume 3
Street Sweeping and Vacuuming (SS) SM-7
November 2010 Urban Drainage and Flood Control District SS-1
Urban Storm Drainage Criteria Manual Volume 3
Photograph SS-1. A street sweeper removes sediment and potential
pollutants along the curb line at a construction site. Photo courtesy of
Tom Gore.
Description
Street sweeping and vacuuming remove
sediment that has been tracked onto
roadways to reduce sediment transport
into storm drain systems or a surface
waterway.
Appropriate Uses
Use this practice at construction sites
where vehicles may track sediment
offsite onto paved roadways.
Design and Installation
Street sweeping or vacuuming should be
conducted when there is noticeable
sediment accumulation on roadways adjacent to the construction site. Typically, this will be concentrated
at the entrance/exit to the construction site. Well-maintained stabilized construction entrances, vehicle
tracking controls and tire wash facilities can help reduce the necessary frequency of street sweeping and
vacuuming.
On smaller construction sites, street sweeping can be conducted manually using a shovel and broom.
Never wash accumulated sediment on roadways into storm drains.
Maintenance and Removal
Inspect paved roads around the perimeter of the construction site on a daily basis and more
frequently, as needed. Remove accumulated sediment, as needed.
Following street sweeping, check inlet protection that may have been displaced during street
sweeping.
Inspect area to be swept for materials that may be hazardous prior to beginning sweeping operations.
Street Sweeping/ Vacuuming
Functions
Erosion Control No
Sediment Control Yes
Site/Material Management Yes
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APPENDIX C
LANDSCAPE PLAN
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APPENDIX D
PERMITS / APPLICATIONS
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APPENDIX E
INSPECTION LOGS
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APPENDIX F
CONTRACTOR INSERTS
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APPENDIX G
CONTRACTOR INSERTS