HomeMy WebLinkAboutFOOTHILLS MALL REDEVELOPMENT, MULTI-FAMILY - FDP - FDP150048 - SUBMITTAL DOCUMENTS - ROUND 1 - STORMWATER-RELATED DOCUMENTS (3)FOOTHILLS MALL MULTI-FAMILY
STANDARD OPERATING PROCEDURES
FOR STORMWATER BMPS
PREPARED FOR
McWhinney Real Estate Services Inc.
Loveland, Colorado
PREPARED BY
Olsson Associates
5285 McWhinney Boulevard, Suite 160
Loveland, CO 80538
December 2015
Olsson Associates Project No. 015-0720
Foothills Mall Multi-Family Standard Operating Procedures
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Table of Contents
1.0 Purpose ............................................................................................................................. 1
2.0 Reference .......................................................................................................................... 1
3.0 Responsibility .................................................................................................................... 1
4.0 On Site BMPs .................................................................................................................... 1
5.0 Permeable Pavers ............................................................................................................. 1
5.1 Inspection ................................................................................................................. 1
5.2 Debris Removal, Sweeping, and Vacuuming ............................................................ 1
5.3 Snow Removal ......................................................................................................... 2
5.4 Full and Partial Replacement of the Pavement or Infill Material ................................ 2
6.0 Rain Garden (Bioretetnion) ................................................................................................ 2
6.1 Inspection ................................................................................................................. 3
6.2 Debris and Litter Removal ........................................................................................ 3
6.3 Mowing and Plant Care ............................................................................................ 3
6.4 Irrigation Scheduling and Maintenance ..................................................................... 3
6.5 Replacement of Wood Mulch .................................................................................... 3
6.6 Sediment Removal and Growing Media Replacement .............................................. 3
7.0 Strom Drains, Manholes, Inlets, Pans and Chases ............................................................ 4
7.1 Inspection ................................................................................................................. 4
7.2 Debris and Litter Removal ........................................................................................ 4
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1.0 Purpose
The purpose of the standard operating procedures is to:
Identify the storm drainage best management practices (BMPs) within the site.
Identify BMP maintenance responsibility.
Identify maintenance activities for the BMPs.
Identifying the maintenance schedule for each BMP.
2.0 Reference
Urban Storm Drainage Criteria Manual (USDCM), Volumes 3, published by the Urban Drainage
and Flood Control District, Denver, Colorado, November 2010
3.0 Responsibility
The BMPs listed are privately owned and will be maintained by the property manager.
4.0 On Site BMPs
The following stormwater facilities contained within site are subject to standard operating
procedure requirements:
Permeable Paving
Rain Garden (Bioretention)
Storm Drains, Manholes, Inlets, Pans and Chases
The general location of the BMPs can be found on Exhibit A “BMP Location Map” The design
and details of the BMPs can be found on the Utility Plans and Landscape Plans for the site.
5.0 Permeable Pavers
The key maintenance objective for any permeable pavement system is to know when runoff is
no longer rapidly infiltrating into the surface, which is typically due to void spaces becoming
clogged and requiring sediment removal. This section identifies key maintenance
considerations for various types of permeable pavement BMPs.
5.1 Inspection
Inspect pavement condition and observe infiltration at least annually, either during a rain event
or with a garden hose to ensure that water infiltrates into the surface. Video, photographs, or
notes can be helpful in measuring loss of infiltration over time. Systematic measurement of
surface infiltration of pervious concrete, Permeable Interlocking Concrete Pavers (PICP), and
concrete grid pavement can be accomplished using ASTM C1701 Standard Test Method for
Infiltration Rate of In Place Pervious Concrete.
5.2 Debris Removal, Sweeping, and Vacuuming
All Pavements: Debris should be removed, routinely, as a source control measure.
Typically, sites that require frequent sweeping already plan for this activity as part of
their ongoing maintenance program. This is frequently performed with a broom
sweeper. Although this type of sweeper can be effective at removing solids and debris
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from the surface, it will not remove solids from the void space of a permeable pavement.
Use a vacuum or regenerative air sweeper to help maintain or restore infiltration. If the
pavement has not been properly maintained, a vacuum sweeper will likely be needed.
PICP, Concrete Grid Pavements (with aggregate infill) and Pervious Concrete: Use a
regenerative air or vacuum sweeper after any significant site work (e.g., landscaping)
and approximately twice per year to maintain infiltration rates. This should be done on a
warm dry day for best results. Do not use water with the sweeper. The frequency is site
specific and inspections of the pavement may show that biannual vacuuming is more
frequent than necessary. After vacuuming PICP and Concrete Grid Pavers, replace infill
aggregate as needed.
5.3 Snow Removal
In general, permeable pavements do not form ice to the same extent as conventional
pavements. Additionally, conventional liquid treatments (deicers) will not stay at the surface of a
permeable pavement as needed for the treatment to be effective. Sand should not be applied to
a permeable pavement as it can reduce infiltration. Plowing is the recommended snow removal
process. Conventional plowing operations should not cause damage to the pavements.
PICP and Concrete Grid: Deicers may be used on PICP and grid pavers; however, it
may not be effective for the reason stated above. Sand should not be used. If sand is
accidently used, use a vacuum sweeper to remove the sand. Mechanical snow and ice
removal should be used.
Pervious Concrete: Do not use liquid or solid deicers or sand on pervious concrete.
Deicers can damage the concrete and sand will reduce infiltration. Mechanical snow
and ice removal should be used.
5.4 Full and Partial Replacement of the Pavement or Infill Material
PICP and Concrete Grid: Concrete pavers, when installed correctly, should have a long
service life. If a repair is required, it is frequently due to poor placement of the paver
blocks. Follow industry guidelines for installation and replacement after underground
repairs. If surface is completely clogged and rendering a minimal surface infiltration rate,
restoration of surface infiltration can be achieved by removing the first ½ to 1 inch of
soiled aggregate infill material with a vacuum sweeper. After cleaning, the openings in
the PICP will need to be refilled with clean aggregate infill materials. Replacement of the
infill is best accomplished with push brooms.
Pervious Concrete: Partial replacement of pervious concrete should be avoided. If
clogged, power washing or power blowing should be attempted prior to partial
replacement because saw cutting will cause raveling of the concrete. Any patches
should extend to existing isolated joints. Conventional concrete may be used in patches,
provided that 90 percent of the original pervious surface is maintained.
6.0 Rain Garden (Bioretetnion)
The primary maintenance objective for bioretention, also known as porous landscape detention,
is to keep vegetation healthy, remove sediment and trash, and ensure that the facility is draining
properly. The growing medium may need to be replaced eventually to maintain performance.
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This section summarizes key maintenance considerations for bioretention.
6.1 Inspection
Inspect the infiltrating surface at least twice annually following precipitation events to determine
if the bioretention area is providing acceptable infiltration. Bioretention facilities are designed
with a maximum depth for the WQCV of one foot and soils that will typically drain the WQCV
over approximately 12 hours. If standing water persists for more than 24 hours after runoff has
ceased, clogging should be further investigated and remedied. Additionally, check for erosion
and repair as necessary.
6.2 Debris and Litter Removal
Remove debris and litter from the infiltrating surface to minimize clogging of the media. Remove
debris and litter from the overflow structure.
6.3 Mowing and Plant Care
All vegetation: Maintain healthy, weed-free vegetation. Weeds should be removed
before they flower. The frequency of weeding will depend on the planting scheme and
cover. When the growing media is covered with mulch or densely vegetated, less
frequent weeding will be required.
Grasses: When started from seed, allow time for germination and establishment of
grass prior to mowing. If mowing is required during this period for weed control, it should
be accomplished with hand-held string trimmers to minimize disturbance to the seedbed.
After established, mow as desired or as needed for weed control. Following this period,
mowing of native/drought tolerant grasses may stop or be reduced to maintain a length
of no less than 6 inches. Mowing of manicured grasses may vary from as frequently as
weekly during the summer, to no mowing during the winter.
6.4 Irrigation Scheduling and Maintenance
Adjust irrigation throughout the growing season to provide the proper irrigation application rate
to maintain healthy vegetation. Less irrigation is typically needed in early summer and fall, while
more irrigation is needed during the peak summer months. Native grasses and other drought
tolerant plantings should not typically require routine irrigation after establishment, except during
prolonged dry periods.
Check for broken sprinkler heads and repair them, as needed. Completely drain the irrigation
system before the first winter freeze each year. Upon reactivation of the irrigation system in the
spring, inspect all components and replace damaged parts, as needed.
6.5 Replacement of Wood Mulch
Replace wood mulch only when needed to maintain a mulch depth of up to approximately 3
inches. Excess mulch will reduce the volume available for storage.
6.6 Sediment Removal and Growing Media Replacement
If ponded water is observed in a bioretention cell more than 24 hours after the end of a runoff
event, check underdrain outfall locations and clean-outs for blockages. Maintenance activities
to restore infiltration capacity of bioretention facilities will vary with the degree and nature of the
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clogging. If clogging is primarily related to sediment accumulation on the filter surface,
infiltration may be improved by removing excess accumulated sediment and scarifying the
surface of the filter with a rake. If the clogging is due to migration of sediments deeper into the
pore spaces of the media, removal and replacement of all or a portion of the media may be
required. The frequency of media replacement will depend on site-specific pollutant loading
characteristics. Although surface clogging of the media is expected over time, established root
systems promote infiltration. This means that mature vegetation that covers the filter surface
should increase the life span of the growing media, serving to promote infiltration even as the
media surface clogs.
7.0 Strom Drains, Manholes, Inlets, Pans and Chases
Frequent inspections (approximately every three months) are recommended in the first two
years in order to determine the appropriate interval of maintenance for a given structure. This
section provides general recommendations for assorted structures.
7.1 Inspection
Inspect structures at least quarterly for the first two years of operation and then twice a year for
the life of the structure if a reduced inspection schedule is warranted based on the initial two
years. Specifically look for debris that could cause the structure to not bypass flows. Strong
odors may also indicate that the facility is not draining properly. Use a video camera to inspect
the condition of structures if needed.
7.2 Debris and Litter Removal
Remove debris and litter from manholes and inlets to minimize clogging. Cleanout pipes as
needed. If the integrity of the pipe is compromised, then repair the damaged section(s).
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TEL 970.431.7733
Loveland, CO 80538
Suite 160
5285 McWhinney Boulevard
LOT 8 +
VAC TULANE PORTION LOT 1 +
VAC TULANE
PORTION
LOT 1 +
LOT 2