HomeMy WebLinkAboutCOPPERLEAF - FDP - FDP170008 - SUBMITTAL DOCUMENTS - ROUND 1 - EROSION CONTROL LETTER/REPORTEROSION CONTROL REPORT/STORMWATER MANAGEMENT PLAN
FOR
Copperleaf
Subdivision
Prepared by:
Interwest Consulting Group
1218 West Ash, Suite A
Windsor, Colorado 80550
Phone: 970.674.3300
Fax: 970.674.3303
Prepared for:
Brinkman Partners
3528 Precision Drive, Suite 100
Fort Collins, CO 80528
February 8, 2017
TABLE OF CONTENTS
1. INTRODUCTION .................................................................................................................... 1
2. SITE DESCRIPTION ............................................................................................................... 1
3. BMPS FOR STORMWATER POLLUTION PREVENTION ................................................ 5
3.1. Erosion and Sediment Controls ........................................................................................ 5
3.2 Materials Handling and Spill Prevention ......................................................................... 7
4. STORMWATER MANAGEMENT CONTROLS .................................................................. 9
4.1. SWMP Administrator ....................................................................................................... 9
4.2. Identification of Potential Pollution Sources ................................................................... 9
5. FINAL STABILIZATION AND LONG TERM STORMWATER MANAGEMENT ......... 11
6. INSPECTION AND MAINTENANCE ................................................................................. 12
6.1. City of Fort Collins Standard Erosion and Sediment Control Notes ............................. 12
6.2. City of Fort Collins Erosion Control Security Calculations ........................................... 13
7. SWMP IMPLEMENTATION................................................................................................ 15
APPENDIX A—BMP DETAILS ................................................................................................ A
APPENDIX B—EROSION CONTROL PLAN ......................................................................... B
APPENDIX C—CONSTRUCTION SEQUENCE .................................................................... C
APPENDIX D—SOIL INFORMATION ................................................................................... D
LIST OF FIGURES
Figure 1—Vicinity Map…………………………………………………………………………..2
LIST OF TABLES
Table 2.1—On-site Soil Characteristics…………………………………………………………..3
Table 6.1—Erosion Control Cost Estimate……………………………………………………...14
1
1. INTRODUCTION
The primary purpose of preparing and maintaining a stormwater management plan is to
improve the health and quality of the State's urban waterways. The preparation and
maintenance of the plan will contribute to this objective by facilitating an approach to
stormwater management, establishing a program of actions to be used during construction
activities, and describing stormwater management controls and various Best Management
Practices (BMPs) necessary to reduce erosion, sediment and pollutants in stormwater
discharge.
Information concerning the State of Colorado General Permit and Stormwater
Management Plan are not included in the appendices of this report. The site is over one
acre and will require a SWMP permit. This document can be used by the contractor as a
part of the required documentation for the permit.
2. SITE DESCRIPTION
The Copperleaf Subdivision (3425 South Shields) is located in the Southeast Quarter of
Section 27, Township 7 North, Range 69 West of the Sixth Principal Meridian, in the
City of Fort Collins, Larimer County, Colorado.
The project site is located on the west side of South Shields Street about 650 feet north of
West Horsetooth Road. South Shields Street bounds the property on the east, Horsetooth
Commons PUD on the south, Casa Grande Condos on the west and Chaparral PUD on
the north.
The property consists of about 2.9 acres of land and will consist of three new multi-family
buildings, garages and new parking and drive aisles. The total disturbed area for the site
will be 2.9 acres.
2
The site generally slopes in a northeasterly direction at approximately 1.5%. The land
currently contains several buildings and gravel drives. There are no offsite flows
contributing to the site.
The property is not located within a City of Fort Collins Floodplain or FEMA 100-year
floodplain (FEMA Panel 08069C0986G).
Figure 1--Vicinity Map
3
The existing soil type on-site consists of Altvan-Satanta loams (71.2%) and Nunn clay
loam (28.9%) which are classified as Type B and C, respectively, by the Natural
Resources Conservation Service. Please refer to Table 2.1 for additional soil
characteristics.
Table 2.1: On-site Soil Characteristics
Soil Type
Percent
of Site
Hydrologic
Soil Group
K
Factor1
Wind
Group2
Altvan-Satanta loams 0 to 3% slopes 68.9% B 0.28 5
Nunn clay loam, 1 to 3% slopes 28.9% C 0.28 6
Altvan-Satanta loams 3 to 9% slopes 2.3% B 0.28 5
1K factors range from 0.02 to 0.69. The higher value, the more susceptible the soil is to sheet and
rill erosion by water.
2Soils assigned to wind group 1 are the most susceptible to wind erosion, soils assigned to wind
group 8 are the least susceptible.
Overall, the soils on site can be classified as moderately erodible. Please refer to
Appendix D for the on-site soil information from the NRCS Soil Survey of Larimer
County.
4
The anticipated sequence of construction shall progress as follows:
1) Site demolition, if any, and as quickly as possible the installation of perimeter
erosion control measures (other measures as required for erosion control will be
constructed throughout) and the concrete washout and vehicle tracking pad.
2) Clearing, stripping and grading
3) Utility installation
4) Building construction begins
5) Sub-grade preparation for the drives and sidewalks
6) Curb, gutter and sidewalks
7) Paving
8) Final grading and landscaping. All disturbed ground will be impervious (concrete,
asphalt, or building), seeded and mulched, sodded or xeriscaped to permanently
stabilize the site.
The weighted average 10-year runoff coefficient associated with this project is 0.69.
No outside sources of pollution currently exist on this site. Potential pollutant sources
brought onto the site during construction will be discussed (along with spill prevention)
in Section 3.2 below. The anticipated non-stormwater components of discharge with this
project are landscape irrigation return flows. Runoff from the site will flow through the
porous pavers and also toward the proposed inlet and water quality pond. The project is
within the City’s Foothills Master Drainage Basin. The area drains to an existing storm
system located in South Shields Street.
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3. BMPS FOR STORMWATER POLLUTION PREVENTION
3.1. Erosion and Sediment Controls
Structural Practices: Structural practices for the site will consist mainly of concrete
washout structure, vehicle tracking pad, inlet protection, erosion logs and wattles, and
aggregate bags which are described in detail in the following paragraphs. Detail drawings
of these BMPs are also included in Appendix A. These BMPs are expected to change as
the construction progresses and it is the responsibility of the contractor to ensure
appropriate BMPs are in place and/or removed at the appropriate time in the construction
sequence. All temporary and permanent erosion and sediment control practices must be
maintained and repaired as needed to assure continued performance of their intended
function. All BMPs shall be inspected and repaired or replaced as indicated in Section 6
and as required to satisfy the conditions of the Permit.
Concrete washout structure is intended to contain washout liquids and solids that result
from the cleaning of concrete trucks and pumps. Washouts should be placed near the
area where the concrete is being poured.
Vehicle tracking pad is intended to trap mud and sediment within coarse grain material
and provide clean access to public roadways. Wherever construction vehicle access routes
intersect paved public roads a vehicle tracking control pad shall be installed to minimize
the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface.
Pads shall be maintained and refurbished when necessary to obtain their intended result.
Inlet protection, erosion logs and wattles, and aggregate bags prevent sediment from
entering storm drainage systems prior to permanent stabilization of the disturbed site area
via ponding and settling of sediment. Erosion logs at drop inlets shall be placed at the
area inlets on site as inlet protection. Storm inlet protection shall be used at the Type 13
area and Type R sump inlets and must be inspected and maintained after every rainfall
event that produces runoff. Sediment must be removed and rocks replaced. Erosion logs
shall be used in the concrete pans and wattles along South Shields Street. Aggregate bags
shall be used to protect the perimeters of the pervious pavement systems.
Non-Structural Practices: If there are any low sloped areas exposed during land
disturbing activity (stripping, grading, utility installations, stockpiling, filling, etc.) they
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shall be kept in a roughened condition by ripping or disking along land contours until
mulch, vegetation or other permanent erosion control is installed.
If there are any exposed steep sloped areas exposed during land disturbing activity
(stripping, grading, utility installations, stockpiling, filling, etc.) they shall have slope
protection. The contractor shall use a "tracked" vehicle, run perpendicular to slope so that
the tracking runs on the contour to inhibit rill/gully erosion; the contractor may use other
windrow-type methods as necessary.
No soil shall remain exposed by land disturbing activity for more than thirty (30) days.
At that time temporary or permanent erosion control seed/mulch, landscaping, etc. is
required.
Additional Non-Structural Practices are strongly encouraged such as minimizing the
disturbance of soils and vegetation, providing educational materials on disposal
/recycling, spill prevention / clean up, identification and elimination of illicit discharges,
promotion of street sweeping and the development of public education programs.
THE CONTRACTOR SHALL ADD ANY AND ALL BMP’S AND DETAILS
NEEDED FOR SEDIMENT/EROSION CONTROL.
7
3.2 Materials Handling and Spill Prevention
Potential impacts from significant materials and their handling are as follows:
Chemicals, cleaning substances, and petroleum products related to the construction will
be stored within the construction trailer or storage shed where it will not be in contact
with precipitation. No storage of these materials will be allowed outside.
Maintenance of equipment shall not take place on site. Fueling will be accomplished off-
site. Absorbent (kitty litter) will be in the construction trailer and applied on any spill
immediately and the dry material disposed of properly and legally.
All construction waste shall be disposed of in the available dumpsters throughout the
workday. Liquid wastes will be hauled off site and disposed of properly and legally.
Any cleaning or maintenance of small equipment will be required to be done within a
containment device (horse trough or small “kiddy pool”) and the liquid disposed of
properly and legally.
In the event of any spill, the SWMP Administrator shall be immediately notified.
Spills can be broken into three categories. Their definitions and the procedures required
to address the spills are as follow:
Minor Spill – A spill generally of less than 5 gallons which is unlikely to reach adjacent
waters (i.e. equipment leak).
Procedure:
a. Stop the source of the spill.
b. Contain the spillage.
c. Contact the SWMP Administrator.
d. Clean up the spill with on-site absorbent material (kitty litter)
e. Dispose of the dry material properly or legally.
f. Document the spill and the response in the SWMP including dates
and times – verify that the pollutants are completely cleaned up.
g. Include incident in the following training meeting.
h. Provide information to the City of Fort Collins at the next regular
inspection.
8
Significant Spill – A spill of pollutants or oils of any size that will likely or has reached
adjacent waters, may endanger health or the environment, or which may exceed a water
quality standard.
Procedure:
a. Stop the source of the spill.
b. Contain the spillage.
c. Contact the SWMP Administrator.
d. Clean up the spill with on-site absorbent material (kitty litter)
e. Dispose of the dry material properly and legally.
f. Document the spill and the response in the SWMP – verify that the
pollutants are completely cleaned up.
g. Notify the City of Fort Collins (970) 221-6700 and the Colorado
Department of Public Health and Environment spill reporting line
(877) 518-5608 of the spill.
h. Notify the same two entities above with a written submission
(outlined within the permit) within 5 calendar days.
i. Include incident in the following training meeting.
Hazardous Spill – A spill of a dangerous substance requiring expert cleanup.
Procedure:
a. Secure the area – do not approach the spill.
b. Offer first aid to any injured parties.
c. Call 911 and describe the nature of the spill and any injuries.
d. If possible, isolate downstream areas from the spill (for example,
cover an inlet that is downstream and a safe distance from the spill
with plastic and soil).
e. Contact the SWMP Administrator.
f. Document the spill and the response in the SWMP
g. Notify the City of Fort Collins (970) 221-6700 and the Colorado
Department of Public Health and Environment spill reporting line
(877) 518-5608 of the spill.
h. Notify the same two entities above with a written submission
(outlined within the permit) within 5 calendar days.
i. Include incident in the following training meeting.
9
4. STORMWATER MANAGEMENT CONTROLS
4.1. SWMP Administrator
The Local Contact and SWMP Administrator is (INSERT CONTACT NAME,
POSITION, COMPANY, AND PHONE NUMBER).
(INSERT CONTACT) will be responsible for developing, implementing, maintaining,
and revising the SWMP. (INSERT CONTACT) will also be responsible for required
inspections and coordinating and documenting changes or repairs resulting from
inspections. (INSERT CONTACT) will be responsible for the training and enforcement
aspects of the SWMP and he is the first point of contact for any stormwater issues.
4.2. Identification of Potential Pollution Sources
The permit identifies 13 potential sources that must be evaluated for their potential to
contribute pollutants to stormwater discharge. These items have been evaluated below
for this project:
1) Disturbed and stored soil – YES – The construction will require that areas
be disturbed exposing soil including foundation construction, paving and
repaving, slope construction, and demolition required as shown on the
plans. BMPs will include the sediment trap, and erosion logs, aggregate
bags or inlet protection on proposed inlets, proposed flared end section and
proposed curb and gutter, minimizing disturbance of existing vegetation
and hard surfaces, and slope roughening and tracking of slopes after
disturbance and prior to landscaping, paving, or building will be
implemented.
2) Vehicle tracking of sediment – YES – The construction will require that
subgrade be prepared for pavement and that vehicles drive on unpaved
surfaces to the proposed buildings and utility improvement locations.
BMPs will include a policy that vehicles be clean prior to entering the site
and, if they become muddy during construction or earthwork activities,
mud is removed by hand from the vehicle prior to departing the site in an
area near the vehicle tracking pad. Any soil that is tracked from the site is
to be disposed of in the trash dumpster by sweeping or scraping the
material off the street. Any muddy vehicle will use the vehicle tracking
pad prior to leaving the site.
3) Management of contaminated soil – NO – Soil borings do not indicate any
existing contamination. If encountered, dispose of material properly and
legally.
10
4) Loading and unloading operations – YES – Chemicals and petroleum
products will be brought to the site. Anytime these are being transported,
they will be in a sealed container.
5) Outdoor storage activities – YES – Inert materials such as wood and stone
will be stored outside and will likely be covered with tarps or plastic, but
are not pollutant sources and are not covered by the permit. Chemicals
and petroleum products will be stored within the construction trailer or
storage shed. Cement and mortar bags (if not contained in a vehicle or
storage shed) will be completely covered with plastic to avoid contact with
precipitation.
6) Vehicle and equipment maintenance and fueling – YES – Vehicle
maintenance and fueling will take place. No fuel will be stored on site.
7) Significant dust or particulate generating processes – NO – The area of
heavy construction is very limited; however, in order to control the dust or
particulate generating process, a water truck or similar watering device
will be available at all times.
8) Routine maintenance activities involving fertilizers, pesticides, detergents,
fuels, solvents, oils, etc. – YES – Fertilizers and pesticides will not be
used. Any cleaning or maintenance of small equipment will be required to
be done within a containment device (horse trough or small “kiddy pool”
and the liquid disposed of properly and legally.
9) On-site waste management – YES – The site construction will result in
construction waste. A dumpster for trash and a dumpster for bulk
recycling will be on the site. Waste will be hauled to the dumpsters by
hand or in loaders. Dumpsters will be hauled off as needed. No
construction waste will be left outside overnight without being located in a
dumpster. No construction debris (including broken concrete) may be
buried on the site.
10) Concrete truck/equipment washing – YES – One mobile concrete washout
will be provided on site. This will be used for trucks and for any
masonry/concrete tools.
11) Dedicated asphalt of concrete batch plants – NO – None on this project.
12) Non-structural waste sources such as worker trash and portable toilets –
YES –Trash dumpster will be available for worker’s trash and will be
located near the construction trailer and emptied weekly. Portable toilets
will be staked on site near the construction trailer.
13) Other areas where potential spills can occur – NO – The above 12 items
are adequate for the anticipated construction process.
CONTRACTOR TO UPDATE THE ABOVE INFORMATION WITH EXACT
LOCATIONS OF THE CONCRETE WASHOUT, DUMPSTERS, AND PORTABLE
TOILETS PRIOR TO COMMENCEMENT OF CONSTRUCTION AND UPDATED AS
NECESSARY THROUGHOUT THE CONSTRUCTION SEQUENCE.
11
5. FINAL STABILIZATION AND LONG TERM STORMWATER
MANAGEMENT
Long-term erosion control for this site will be the established vegetative cover,
landscaping and xeriscaping along with the completed site improvements (pavement and
buildings).
All disturbed areas will be paved, sodded or mulched.
The soil in such areas shall be thoroughly loosened to a depth of not less than eight (8)
inches; and soil amendments shall be thoroughly incorporated into the soil of such areas
to a depth of at least six (6) inches by tilling, discing or other suitable method, at a rate of
at least three (3) cubic yards of soil amendment per one thousand (1,000) square feet of
area to be planted, unless at least four (4) inches of loose top soil has been placed on the
area after completion of construction activity on top of not less than four (4) inches of
loosened subgrade soils.
Final stabilization shall be considered achieved once the over-lot grading is complete and
all vegetation is established. Vegetation shall not be considered established until a
ground cover is achieved which is demonstrated to be mature enough to control soil
erosion (70% of the original vegetative cover of 100%).
12
6. INSPECTION AND MAINTENANCE
Site inspections will be performed to effectively address maintenance, repair, and
adequacy of BMPs. The site inspections will be performed by the SWMP Administrator
or his designee a minimum of once every fourteen (14) calendar days on active
construction sites and within 24 hours after a significant storm event (event causing
erosion). As part of the site inspections the inspector will keep documentation of all
inspections and BMP maintenance, including updated Site Maps indicating new BMPs or
the removal of BMPs since the previous inspection. Blank Site Maps will be utilized and
will be redlined by the SWMP Administrator throughout construction to note all BMPs,
pollutant sources, storage locations, etc.
Any maintenance, repair, or necessary installation of BMPs that are noted during the
inspection must begin immediately. The modifications shall be noted in the SWMP and
the action taken as a result of the inspection shall be noted and certified on or attached to
the original inspection report (date and time that the repair or change was started and
finished and a certification that it was done properly).
6.1. City of Fort Collins Standard Erosion and Sediment Control Notes
1) The City Stormwater Department erosion control inspector must be notified at
least 24 hours prior to any construction on this site.
2) All required BMPs shall be installed prior to any land disturbing activity
(stockpiling, stripping, grading, etc.). All of their required erosion control
measures shall be installed at the appropriate time in the construction sequence as
indicated in the approved project schedule, construction plans, and erosion control
report.
3) Pre-disturbance vegetation shall be protected and retained wherever possible.
Removal or disturbance of existing vegetation shall be limited to the area required
for immediate construction operations, and for the shortest practical period of
time.
4) All soils exposed during land disturbing activity (stripping, grading, stockpiling,
filling, etc.) shall be kept in a roughened condition by ripping or disking along
land contours until mulch, vegetation, or other permanent erosion control is
13
installed. No soils in areas outside project street rights of way shall remain
exposed by land disturbing activity for more than thirty (30) days before required
temporary or permanent erosion control (e.g. seed/mulch, landscaping, etc.) is
installed, unless otherwise approved by the Stormwater Department.
5) The project must be watered and maintained at all times during construction
activities so as to prevent wind-caused erosion. All land disturbing activities shall
be immediately discontinued when fugitive dust impacts adjacent properties, as
determined by the City Engineering Department.
6) All temporary (structural) erosion control measures must be inspected and
repaired or reconstructed as necessary after each runoff event and every 14 days in
order to assure continued performance of their intended function. All retained
sediments, particularly those on paved roadway surfaces, shall be removed and
disposed of in a manner and location so as not to cause their release into any
drainage way.
7) No stockpile shall exceed ten (10) feet in height. All soil stockpiles shall be
protected from sediment transport by surface roughening, watering, and perimeter
silt fencing. Any soil stockpile remaining after 30 days shall be seeded and
mulched.
8) City Ordinance prohibits the tracking, dropping, or depositing of soils or any other
material onto city streets by or from any vehicle. Any inadvertent deposited
material shall be cleaned immediately by the contractor.
6.2. City of Fort Collins Erosion Control Security Calculations
The cost of erosion control for the site was compared to the cost to reseed the entire site
and the greater cost was used to establish the erosion control escrow amount. The cost to
reseed the site is estimated at $4,350.00. Using a multiplier of 1.5 the erosion control
escrow amount would be $6,525.00. The site erosion control cost is estimated at
$9,725.00. Using a multiplier of 1.5 the erosion control escrow amount would be
$14,587.50. The larger sum of the Erosion Control cost and the Reseeding cost shall be
used for the escrow account. Therefore, the Erosion Control Escrow amount is $14,588.
See Table 6.1 for a break-down of the costs associated with seeding and erosion control.
14
Table 6.1: Erosion Control Cost Estimate
ITEM QUANTITY UNIT COST/UNIT TOTAL COST
Inlet Protection (IP-1 & IP-3) 4 EA $ 150.00 $ 600.00
Aggregate Bag (AB) 860 LF $ 5.00 $ 4,300.00
Erosion Log (EL & EL-IP) 18 EA $ 75.00 $ 1,350.00
Concrete Washout (CW) 1 EA $ 800.00 $ 800.00
Vehicle Tracking Pad (VTC) 1 EA $ 1,500.00 $ 1,500.00
Aggregate Bags 265 LF $ 3.50 $ 927.50
Wattles 165 LF $ 1.50 $ 247.50
Subtotal $ 9,725.00
Contingency (50%) $ 4,862.50
Total $ 14,587.50
CITY RESEEDING COST
Reseed/Mulch 2.9 ACRE $ 1,500.00 $ 4,350.00
Subtotal $ 4,350.00
Contingency (50%) $ 2,175.00
Total $ 6,525.00
CALCULATED EROSION CONTROL ESCROW AMOUNT $14,588
Note: Minimum Escrow Amount is $3,000.
15
7. SWMP IMPLEMENTATION
It is the responsibility of the contractor to operate and maintain all facilities and systems
of treatment and control which are installed to achieve compliance with the conditions of
the permit. This includes effective performance, adequate funding, adequate staffing and
training, etc. (see permit).
All personnel on the construction site who will be in a position to affect or be affected by
the SWMP shall be trained prior to beginning work. These individuals will be given
general orientation information regarding the project and SWMP, shown where the
SWMP is physically located, the SWMP will be explained to them and available for their
review, and the enforcement policy will be reviewed. After this training, a certification
that the employee or subcontractor’s employee is familiar with the document and its
procedures will be signed. Copies of these certifications are included in the Appendix.
Throughout the construction, as a part of a weekly safety meeting, the SWMP will be
reviewed with all attendees and any incidents discussed. All attendees shall be logged.
APPENDIX A—BMP DETAILS
B
APPENDIX B—EROSION CONTROL PLAN
C
APPENDIX C—CONSTRUCTION SEQUENCE
Mobilization Demolition Grading
Utilities
Installation
Flat work
Installation
Vertical
Installation Landscape Demobilization
Best Management Practices (BMPs)
Structural "Installation"
Sediment Trap*
Contour Furrows (Ripping / Disking)
Concrete Washout Structure*
Vehicle Tracking Pad*
Erosion Logs* Any prior inlets that could use protecting
Inlet Filter Bags* Any prior inlets that could use protecting
Aggregate Bags* Any prior inlets that could use protecting
Terracing
Collecting Asphalt / Concrete Saw Cutting Waste
*All BMPs to be Removed once Construction is Complete.
Vegetative
Temporary Seeding Planting Any time the site will sit dorment longer than 30 Days.
Mulching/Sealant Any time the site will sit dorment longer than 30 Days.
Permanent Seeding Planting
Sod Installation
Other:
CONSTRUCTION SEQUENCE CHART
D
APPENDIX D—SOIL INFORMATION