HomeMy WebLinkAboutCT 01-05; CALAVERA HILL VILLAGE W; STORMWATER MGMT PLAN VILLAGE W; 2003-08-21STORMWATER MANAGEMENT PLAN
FOR
VILLAGE 'W
FOR
CALAVERA HILLS
CARLSBAD TRACT 01-05
Carlsbad, California
Water Discharge Identification No.
August 21, 2003
PREPARED BY
O'Day Consultants, Inc.
2710 Loker Avenue West, Suite 100
Carlsbad, CA 92008
(760) 931-7700
981020
Table of Contents
Vicinity Map 3
Drainage Study 4
Project Description 4
Pollutants and Conditions of Concem 4
Site Design BMPs 4
Source Control BMPs 5
Structural Treatment BMPs 6
Maintenance 7
Appendices
Appendix A - Village ' W Post Construction BMP Summary Sheet
Appendix B - Selected Source Control BMPs
Appendix C - Selected Treatment Control BMPs
Appendix D - Bioclean Environmental Services, Inc.
Grate Inlet Skimmer Box, Curb Inlet Basket, Nutrient Baffle Box
Report & Data
Appendix E - Flow Treatment Basin
Appendix F - Drainage Study for Calavera Hills-Village 'X'
Appendix G - Hydrology Study for Calavera Hills Village 'Y'
Appendix H - Excerpt of Declaration of Restrictions for Calavera Hills II Planned
Development
Appendix I - Excerpt of Calavera Hills II Resource Agency Permits-Regional Water
Quality Control Board Order No. R98-2002-0014 Waste Discharge
Requirements and Section 401 Certification Dated February 13, 2002
Appendix J - Sample Water Quality Pamphlets
W;\MSOFFICE\WINWORD\981020\ViIlage W SWMP Rpt.doc
VICINITY MAP
NOT TO SCALE
PACIFIC
OCEAN
CITY OF
SAN MARCOS
CITY OF ENCINITAS
VILLAGE W
VILLAGE VICINTIY MAP EXHIBIT
1
PREPARED BY ODAY CONSULTANTS. INC Gi\SDSK\PRaj\981020\DWl3\CALAVERA\9880WVMJ>WG 7-lS-a003 9«3i08 on
Drainage Study
There appeared to be no drainage concems downstream of the site at the time of
investigation.
Project Description
The proposed condition for Village 'W' will be a 37.03-acre, 122-lot single-family
residential sub-division. 6.70 acres will be open space and will remain undisturbed. 5.34
acres will be homeowner's association lots and will be sloped and landscaped. 0.62 acres
will be recreational lots. 7.91 acres will be public right-of-way. The remaining 16.46
acres will be single-family residential lots.
All onsite developed stormwater mnoff will eventually discharge into Basin "BJB"
approximately 900 feet downstream from the site (See Appendix A for Basin "BJB"
location). Approximately 22.64 acres of Village 'W' development will first be
discharged into an existing basin located at the southerly end of the site. This basin will
treat the stormwater prior to discharge. These flows are then discharged into a
stormwater conveyance system along College Boulevard and ultimately into Basin
"BJB". The bypassed portion of Village 'W' development will be discharged into the
stormwater conveyance system along College Boulevard and ultimately into Basin "BJB.
Portions of Village 'U', 'Y', 'X', and College Boulevard will also enter the basin located
at the southerly end of the site. The areas will be addressed in the Stmctural BMP's
section of this report. These areas will be conveyed through an upstream stormwater
conveyance system along College Boulevard prior to being discharged into the Village
'W' onsite basin. These flows will then be treated within the basin and then released
back into the stormwater conveyance system along College Boulevard and ultimately into
Basin "BJB".
Pollutants and Conditions of Concern
The anticipated and potential pollutants that will be generated by this project was
determined using Table 2 of the Storm Water Standards. The following are potential and
anticipated pollutants for this project:
• Sediments
• Nutrients
• Trash and Debris
• Oxygen Demanding Substances
• Oil and Grease
• Bacteria and Vimses
• Pesticides
There are no additional conditions of concems identified at this time.
Site Design BMPs
The BMPs selected for this project were based on the Regional Water Quality Control
Board Order No. R98-2002-0014 Waste Discharge Requirements and Section 401
Certification Dated Febmary 13, 2002 and its exhibit Attachment 1 (See Appendix I for
an excerpt of the Calavera Hills II Resource Agency Permit Report).
Several Site Design BMPs will be used on this project site. See Appendix B for
additional information on the selected Site Design BMPs.
The following Site Design BMPs will be implemented in order to minimize impervious
areas:
• A total of five-foot wide landscaped buffer and eight-foot wide gravel trail
will be incorporated within College Boulevard.
• A total of fourteen feet wide landscaped buffer will be incorporated within
Rich Field Drive, Moon Field Drive, Meadow Drive, and Plains Way
right-of-way.
• All pavement widths with the right-of-way will be built to its required
widths.
• 5.34 acres will either be homeowner's association or recreation lots, and
will be landscaped per Village 'W' landscape plan.
• 6.70 acres will remain undeveloped.
The developer will install the pavement, sidewalk and landscape buffer.
All exposed earth will be hydroseeded or landscaped per Village W's landscape plans
and will be installed by the developer.
The developed site will be irrigated to maintain all vegetation and will be installed by the
developer.
Source Control BMPs
The following Source Control BMPs will be incorporated to the site:
• All stormwater curb inlets will be stamped with thermoplastic letterings
"No Dumping -1 Live Downsfream"
Curb inlet stamps will be placed on all curb inlets onsite and will be placed by the
developer.
Water quality educational pamphlets will also be sent to tenants and contractors. The
developers will be responsible for ensuring the confractors receive the pamphlets prior to
constmction. The homeowner's association will be responsible for sending these
educational pamphlets to all new tenants and once a year. See Appendix J for sample
pamphlets.
Mechanical sweeping shall be used to clean the street. Street sweeping shall be done
twice a month and the homeowner's association will provide the service.
Structural Treatment BMPs
Storm drainage inserts and flow treatment basin will be used for Stmctural Treatment
BMPs.
The drainage inserts will be Curb Inlet Baskets. The drainage inserts are Suntree
Technologies Inc. products. See Appendix D for product information. Drainage inserts
will be installed in every onsite curb inlet.
The flow treatment basin will be located at the southerly end of the Village 'W'
development (See Appendix E for additional information). The basin will be used to
treat low flows for Village 'W', portions of Village 'U', 'Y', and 'X', and upstream
portion of College Boulevard. The bottom of this basin will be sloped at approximately
1.5 percent and will be grass lined to collect stormwater-generated pollutants.
The total area to be treated by the flow treatment basin is approximately 68.18 acres.
22.64 acres will be flows from Village 'W', 13.50 acres will be flows from Village 'Y'
and 16.38 acres will be flows from Village 'X'.
Various C values were used throughout the sites and are as follows:
Village 'W'; C = 0.55
Village 'U'; C = 0.70
Village 'Y'; Ci = 0.85; C2 = 0.98
Cl was used for tlte commercial pad area and C2 was used for tiie street
entering College Boulevard.
Village'X';C-0.55
College Boulevard; C = 0.98
The areas entering the basin are as follows:
Village 'W' - 22.64 acres
Village'U' - 13.50 acres
Village 'Y' Ai = 0.38 acres; A2 = 0.20 acres
Al was used for tiie commercial pad area and A2 was used for the street
entering College Boulevard.
Village 'X' = 16.38 acres
College Boulevard =15.08 acres
The required low flow to be treated was determined using a rainfall intensity value of 0.2
inches per hour. The total required low flow to be freated is approximately 9.24 cfs.
Two low flow pipes (Line 'E-2' and 'N') will be used to convey these flows into the
treatment basin. One pipe (Line 'E-2) will convey low flows from Village 'W' and will
discharge flows into the northerly portion of the basin. This pipe will discharge
approximately 2.49 cfs of low flow. The second pipe (Line 'N') will convey the
remaining areas and will discharge flows into the westerly portion of the basin. This pipe
will discharge approximately 6.75 cfs of low flow.
The drainage inserts and flow freatment basins will reduce the following pollutants from
entering downsfream:
• Oxygen Demanding Substances
• Nitrate and Nitrite
• Nitrogen
• Oil and Grease
• Phosphate
• Solids
Maintenance
The post constmction BMP's will be maintained as follows (See Village 'X' Post
Constmction BMP Summary Sheet in Appendix A for BMP maintenance information):
Streets and Sidewalks: City of Carlsbad
Catch Basin Inserts: City of Carlsbad
Flow Treatment Basin: Homeowner's Association
Extended Detention Basin (Basin "BJB"): City of Carlsbad
Inlet Basin Labeling: Homeowner's Association
Open Space: Homeowner's Association
Lot Yards: Property Owner
Roof top drainage: Property Owner
Yard drainage: Property Owner
Landscape within ROW: City of Carlsbad Landscape District
Recreational Lot Irrigations: City of Carlsbad
The maintenance of these BMP's is in conformance with Attachment 1 of the Regional
Water Quality Confrol Board Order No. R98-2002-0014 Waste Discharge Requirements
and Section 401 Certification Dated Febmary 13, 2002 (See Appendix I).
Additional maintenance requirements are addressed on Article X Maintenance
Responsibilities of the Declaration of Restrictions for Calavera Hills II Planned
Development. See Appendix H for Article X.
Site Design & Landscape Planning SD-10
Design Objectives
/ Maximize Infiltration
'f Provide Retention
/• Slow Runoff
y IVlinimize Impervious Land
Coverage
Prohibit Dumping of improper
Materials
Contain Pollutants
Collect and Convey
Description
Each project site possesses unique topographic, hydrologic, and vegetative features, some of
which are more suitable for development than others. Integrating and incorporating
appropnate landscape planning methodologies into the project design is the most effective
action that can be done to minimize surface and groundwater contamination from stormwater.
Approacii
Landscape planning should couple consideration of land suitability for urban uses with
consideration of community goals and projected growth. Project plan designs should conserve
natural areas to the extent possible, maximize natural water storage and infiltration
opportunities, and protect slopes and channels.
Suitable Applications
Appropriate applications include residential, commercial and industrial areas planned for
development or redevelopment.
Design Considerations
Design requirements for site design and landscapes planning should conform to applicable
standards and specifications of agencies with jurisdiction and be consistent with applicable
General Plan and Local Area Plan policies.
LC jAi. S OI A.
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January 2003 California Stormwater BI^P Handbool<
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SD-10 Site Design & Landscape Planning
Designing New Installations
Begin the development of a plan for the landscape unit with attention to the following general
principles:
• Formulate the plan on the basis of clearly articulated community goals. Carefully identify
conflicts and choices between retaining and protecting desired resources and community
growth.
• Map and assess land suitability for urban uses. Include the following landscape features in
the assessment: wooded land, open unwooded land, steep slopes, erosion-prone soils,
foundation suitability, soil suitability for waste disposal, aquifers, aquifer recharge areas,
wetiands, floodplains, surface waters, agricultural lands, and various categories of urban
land use. When appropriate, the assessment can highlight outstanding local or regional
resources that the community determines should be protected (e.g., a scenic area,
recreational area, threatened species habitat, farmland, fish mn). Mapping and assessment
should recognize not only these resources but also additional areas needed for their
sustenance.
Project plan designs should conserve natural areas to the extent possible, maximize natural
water storage and infiltration opportunities, and protect slopes and channels.
Conserve Natural Areas during Landscape Planning
If apphcable, the following items are required and must be implemented in the site layout
during the subdivision design and approval process, consistent witii applicable General Plan and
Local Area Plan policies:
• Cluster development on least-sensitive portions of a site while leaving the remaining land in
a natural undisturbed condition.
• Limit clearing and grading of native vegetation at a site to the minimum amount needed to
build lots, allow access, and provide fire protection.
• Maximize trees and other vegetation at each site by planting additional vegetation, clustering
tree areas, and promoting the use of native and/or drought tolerant plants.
• Promote natural vegetation by using paridng lot islands and other landscaped areas.
• Preserve riparian areas and wetlands.
Maximize Natural Water Storage and Infiltration Opportunities Within tiie Landscape Unit
m Promote the conservation of forest cover. Building on land that is already deforested affects
basin hydrology to a lesser extent than converting forested land. Loss of forest cover reduces
interception storage, detention in the organic forest floor layer, and water losses by
evapotranspiration, resulting in large peak runoff increases and either their negative effects
or the expense of countering them with structural solutions.
• Maintain natural storage resei-voirs and drainage corridors, including depressions, areas of
permeable soils, swales, and intermittent streams. Develop and implement policies and
2 of 4 California Stormwater BMP Handbook January 2003
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Site Design & Landscape Planning SD-10
regulations to discourage the clearing, filling, and channelization of these features. Utilize
fhem in drainage networks in preference to pipes, culverts, and engineered ditches.
• Evaluating infiltration opportunities by referring to the stormwater management manual for
the jurisdiction and pay particular attention to the selection criteria for avoiding
groundwater contamination, poor soils, and hydrogeological conditions that cause these
facilities to fail. If necessary, locate developments with large amounts of impervious
surfaces or a potential to produce relatively contaminated ranoff away from groundwater
recharge areas.
Protection of Slopes and Cliannels during Landscape Design
• Convey ranoff safely from the tops of slopes.
• Avoid disturbing steep or unstable slopes.
• Avoid disturbing natural channels.
• Stabilize disturbed slopes as quickly as possible.
• Vegetate slopes with native or drought tolerant vegetation.
• Control and treat flows in landscaping and/or other controls prior to reaching existing
natural drainage systems.
• Stabilize temporary and permanent channel crossings as quickly as possible, and ensure that
increases in ran-off velocity and frequency caused by the project do not erode the channel.
• Install energy dissipaters, such as riprap, at the outiets of new storm drains, culverts,
conduits, or channels that enter unlined channels in accordance with applicable
specifications to minimize erosion. Energy dissipaters shall be installed in such a way as to
minimize impacts to receiving waters.
• Line on-site conveyance channels where appropriate, to reduce erosion caused by increased
flow velocity due to increases in tributary impervious area. The first choice for linings
should be grass or some other vegetative surface, since these materials not only reduce
ranoff velocities, but also provide water quality benefits from filtration and infiltration. If
velocities m the channel are high enough to erode grass or other vegetative Unings, riprap,
concrete, soil cement, or geo-grid stabilization are other alternatives.
• Consider other design principles that are comparable and equally effective.
Redeveloping Existing Installations
Variousjurisdictional stonnwater management and mitigation plans (SUSMP, WQMP, etc.)
define "redevelopment" in terms of amounts of additional impervious area, increases in gross
floor area and/or exterior constraction, and land disturbing activities with stractural or
impervious surfaces. The definition of " redevelopment" must be consulted to determine
whether or not the requirements for new development apply to areas intended for
redevelopment. Ifthe definition applies, the steps outiined under "designing new installations"
above should be followed.
January 2003 California Stormwater BMP Handbook 3 of 4
New Development and Redevelopment
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SD-10 Site Design & Landscape Planning
Redevelopment may present significant opportunity to add features which had not previously
been implemented. Examples include incorporation of depressions, areas of permeable soils,
and swales in newly redeveloped areas. While some site constraints may exist due to the status
of already existing infrastracture, opportunities should not be missed to maximize infiltration,
slow ranoff, reduce impervious areas, disconnect directiy connected impervious areas.
Other Resources
A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County
Department of Public Works, May 2002.
Stormwater Management Manual for Westem Washington, Washington State Department of
Ecology, August 2001.
Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of
San Diego, and Cities in San Diego County, Febraary 14,2002.
Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood
Control District, and the Incorporated Cities of Orange County, Draft Febraary 2003.
Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures,
July 2002.
4 of 4 Califomia Stormwater BMP Handbook January 2003
New Development and Redevelopment
www.cabmphandbooks.com
Roof Runoff Controls SD-11
Rain Garden
Design Objectives
y Maximize Infiltration
y Provide Retention
y Slow Runoff
Minimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
y Contain Pollutants
Collect and Convey
Description
Various roof ranoff controls are available to address stormwater
that drains off rooftops. The objective is to reduce the total volume and rate of ranoff from
individual lots, and retain the pollutants on site that may be picked up from roofing materials
and atmospheric deposition. Roof ranoff controls consist of directing the roof ranoff away from
paved areas and mitigating flow to the storm drain system through one of several general
approaches: cisterns or rain barrels; dry wells or infiltration trenches; pop-up emitters, and
foundation planting. The first three approaches require the roof ranoff to be contained in a
gutter and downspout system. Foundation planting provides a vegetated strip under the drip
line of the roof.
Approach
Design of individual lots for single-family homes as well as lots for higher density residential and
commercial stractures should consider site design provisions for containing and infiltrating roof
runoff or directing roof ranoff to vegetative swales or buffer areas. Retained water can be reused
for watering gardens, lawns, and trees. Benefits to the environment include reduced demand for
potable water used for irrigation, improved stormwater quality, increased groundwater
recharge, decreased ranoff volume and peak flows, and decreased flooding potential.
Suitable Applications
Appropriate applications include residential, commercial and industrial areas planned for
development or redevelopment.
Design Considerations
Designing Neiv Installations
Cisterns or Rain Barrels
One method of addressing roof runoff is to direct roof downspouts
to cisterns or rain barrels. A cistern is an above ground storage
vessel with either a manually operated valve or a pennanently open
outlet. Roof runoff is temporarily stored and tiien released for
irrigation or infiltration between storms. The number of rain
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SD-11 Roof Runoff Controls
barrels needed is a function of the rooftop area. Some low impact developers recommend that
every house have at least 2 rain barrels, with a minimum storage capacity of 1000 liters. Roof
barrels serve several purposes including mitigating the first flush from the roof which has a high
volume, amount of contaminants, and thermal load. Several types of rain barrels are
commercially available. Consideration must be given to selecting rain barrels that are vector
proof and childproof. In addition, some barrels are designed with a bypass valve that filters out
grit and other contaminants and routes overflow to a soak-away pit or rain garden.
If the cistem has an operable valve, the valve can be closed to store stormwater for irrigation or
infiltration between storms. This system requires continual monitoring by the resident or
grounds crews, but provides greater flexibility in water storage and metering. If a cistem is
provided with an operable valve ahd water is stored inside for long periods, the cistern must be
covered to prevent mosquitoes from breeding.
A cistern system with a permanentiy open outiet can also provide for metering stormwater
ranoff. If the cistern outiet is significantiy smaller than the size of the downspout inlet (say V4 to
V2 inch diameter), ranoff will build up inside the cistern during storms, and will empty out
slowly after peak intensities subside. This is a feasible way to mitigate the peak flow increases
caused by rooftop impervious land coverage, especially for the frequent, small storms.
Dry wells and Infiltration Trendies
Roof downspouts can be directed to dry wells or infiltration trenches. A dry well is constracted
by excavating a hole in the ground and filling it with an open graded aggregate, and allowing the
water to fill the dry well and infiltrate after fhe storm event. An underground connection from
the downspout conveys water into the dry well, allowing it to be stored in the voids. To
minimize sedimentation from lateral soil movement, the sides and top of the stone storage
matrix can be wrapped in a penneable filter fabric, though the bottom may remain open. A
perforated observation pipe can be inserted vertically into the dry well to allow for inspection
and maintenance.
In practice, dry wells receiving ranoff from single roof downspouts have been successful over
long periods because they contain very little sediment. They must be sized according to the
amount of rooftop ranoff received, but are typically 4 to 5 feet square, and 2 to 3 feet deep, with
a minimum of i-foot soil cover over the top (maximum depth of 10 feet).
To protect the foundation, dry wells must be set away from the building at least 10 feet. They
must be installed in solids that accommodate infiltration. In poorly drained soils, dry wells have
very limited feasibility.
Infiltration trenches function in a similar manner and would be particularly effective for larger
roof areas. An infiltration trench is a long, narrow, rock-filled trench with no outlet that receives
stormwater ranoff. These are described under Treatment Controls.
Pop-up Drainage Emitter
Roof downspouts can be directed to an underground pipe that daylights some distance from the
building foundation, releasing the roof ranoff through a pop-up emitter. Similar to a pop-up
irrigation head, the emitter only opens when there is flow from the roof The emitter remains
flush to the ground during dry periods, for ease of lawn or landscape maintenance.
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Roof Runoff Controls SD-11
Foundation Planting
Landscape planting can be provided around the base to allow increased opportunities for
stormwater infiltration and protect the soil from erosion caused by concentrated sheet flow
coming off the roof Foundation plantings can reduce the physical impact of water on the soil
and provide a subsurface matrix of roots that encourage infiltration. These plantings must be
sturdy enough to tolerate the heavy ranoff sheet flows, and periodic soil saturation.
Redeveloping Existing Installations
Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.)
define "redevelopment" in terms of amounts of additional impervious area, increases in gross
floor area and/or exterior construction, and land disturbing activities with stractural or
impervious surfaces. The definition of " redevelopment" must be consulted to determine
whether or not the requirements for new development apply to areas intended for
redevelopment. If the definition applies, the steps outiined under "designing new installations"
above should be followed.
Supplemental Information
Examples
• City of Ottawa's Water Links Surface -Water Quality Protection Program
• City of Toronto Downspout Disconnection Program
• City of Boston, MA, Rain Barrel Demonstration Program
Other Resources
Hager, Marty Catherine, Stormwater, "Low-Impact Development", January/February 2003.
www.stormh20.com
Low Impact Urban Design Tools, Low Impact Development Design Center, Beltsville, MD.
www.lid-stormwater.net
Start at the Source, Bay Area Stormwater Management Agencies Association, 1999 Edition
January 2003 California Stormwater BMP Handbook 3 of 3
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Efficient Irrigation SD-12
Design Objectives
-/ Maximize Infiltration
•/ Provide Retention
y Slow Runoff
Minimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
Contain Pollutants
Collect and Convey
Description "~— ——
Irrigation water provided to landscaped areas may result in excess irrigation water being
conveyed into stormwater drainage systems.
Approach
Project plan designs for development and redevelopment should include application methods of
irrigation water that minimize ranoff of excess irrigation water into the stormwater conveyance
system.
Suitable Applications
Appropriate apphcations include residential, commercial and industrial areas planned for
development or redevelopment. (Detached residential single-family homes are typically
excluded from this requirement.)
Design Considerations
Designing New Installations
The following methods to reduce excessive irrigation runoff should be considered, and
incorporated and implemented where determined applicable and feasible by the Permittee:
• Employ rain-triggered shutoff devices to prevent irrigation after precipitation.
• Design irrigation systems to each landscape area's specific water requirements.
• Include design featuring flow reducers or shutoff valves triggered by a pressure drop to
control water loss in the event of broken sprinkler heads or hnes.
• Implement landscape plans consistent with County or City water conservation resolutions,
which may include provision of water sensors, programmable
irrigation times (for short cycles), etc. —ft^- ^Pl S Cl A
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SD-12 Efficient Irrigation
a Design timing and application methods of inigation water to minimize the runoff of excess
irrigation water into the storm water drainage system.
• Group plants with similar water requirements in order to reduce excess irrigation runoff and
promote surface filtration. Choose plants with low irrigation requirements (for example,
native or drought tolerant species). Consider design features such as:
- Using mulches (such as wood chips or bar) in planter areas without ground cover to
minimize sediment in ranoff
- Installing appropriate plant materials for the location, in accordance with amount of
sunUght and climate, and use native plant materials where possible and/or as
recommended by the landscape architect
- Leaving a vegetative barrier along the property boundary and interior watercourses, to
act as a pollutant filter, where appropriate and feasible
- Choosing plants that minimize or eliminate the use of fertilizer or pesticides to sustain
growth
• Employ other comparable, equally effective methods to reduce irrigation water ranoff.
Redeveloping Existing Installations
Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.)
define "redevelopment" in terms of amounts of additional impervious area, increases in gross
floor area and/or exterior construction, and land disturbing activities with structural or
impervious surfaces. The definition of " redevelopment" must be consulted to determine
whether or not the requirements for new development apply to areas intended for
redevelopment. If the definition applies, the steps outlined under "designing new installations"
above should be followed.
Other Resources
A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County
Department of Public Works, May 2002.
Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of
San Diego, and Cities in San Diego County, Febraary 14, 2002.
Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood
Control District, and the Incorporated Cities of Orange County, Draft Febraary 2003.
Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures,
July 2002.
2 of 2 California Stormwater BMP Handbook January 2003
New Development and Redevelopment
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storm Drain Signage SD-13
Design Objectives
Maximize Infiltration
Provide Retention
Slow Runoff
Minimize Impervious Land
Coverage
Prohibit Dumping of Improper
Materials
Contain Pollutants
Collect and Convey
Description — .
Waste materials dumped into storm drain inlets can have severe impacts on receiving and
ground waters. Posting notices regarding discharge prohibitions at storm drain inlets can
prevent waste dumping. Storm drain signs and stencils are highly visible source controls that
are typically placed directiy adjacent to storm drain inlets.
Approach
The stencil or affixed sign contains a brief statement that prohibits dumping of improper
materials into the urban ranoff conveyance system. Storm drain messages have become a
popular method of alerting the pubhc about the effects of and the prohibitions against waste
disposal.
Suitable Applications
Stencils and signs alert the pubhc to the destination of pollutants discharged to the storm drain.
Signs are appropriate in residential, commercial, and industrial areas, as well as any other area
where contributions or dumping to storm drains is likely.
Design Considerations
Storm drain message markers or placards are recommended at all storm drain inlets within the
boundary of a development project. The marker should be placed in clear sight facing toward
anyone approaching the inlet from either side. All storm drain inlet locations should be
identified on the development site map.
Designing New Installations
The following methods should be considered for inclusion in the project design and show on
project plans:
Provide stenciUng or labeling of all storm drain inlets and catch
basins, constracted or modified, within the project area with
prohibitive language. Examples include "NO DUMPING -California
Stormwater
Quality
Association
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SD-13 Storm Drain Signage
DRAINS TO OCEAN" and/or other graphical icons to discourage illegal dumping.
• Post signs with prohibitive language and/or graphical icons, which prohibit illegal dumping
at public access points along channels and creeks within the project area.
Note - Some local agencies have approved specific signage and/or storm drain message placards
for use. Consult local agency stormwater staff to detemiine specific requirements for placard
types and methods of application.
Redeveloping Existing Installatioivs
Various jurisdictional stormwater management and mitigation plans (SUSMP, WQMP, etc.)
define "redevelopment" in terms of amounts of additional impei-vious area, increases in gross
floor area and/or exterior constraction, and land disturbing activities witii structural or
impei-vious surfaces. If the project meets the definition of "redevelopment", then the
requirements stated under " designing new installations" above should be included in all project
design plans.
Additional Information
Maintenance Considerations
• Legibility of markers and signs should be maintained. If required by the agency with
jurisdiction over the project, the owner/operator or homeowner's association should enter
into a maintenance agreement with the agency or record a deed restriction upon the
property title to maintain the legibility of placards or signs.
Placement
m Signage on top of curbs tends to weather and fade.
• Signage on face of curbs tends to be worn by contact with vehicle tires and sweeper brooms.
Supplemental Information
Examples
• Most MS4 programs have storm drain signage programs. Some MS4 programs will provide
stencils, or arrange for volunteers to stencil storm drains as part of their outreach program.
Other Resources
A Manual for the Standard Urban Stormwater Mitigation Plan (SUSMP), Los Angeles County
Department of Public Works, May 2002.
Model Standard Urban Storm Water Mitigation Plan (SUSMP) for San Diego County, Port of
San Diego, and Cities in San Diego County, February 14, 2002.
Model Water Quality Management Plan (WQMP) for County of Orange, Orange County Flood
Control District, and the Incorporated Cities of Orange County, Draft February 2003.
Ventura Countywide Technical Guidance Manual for Stormwater Quality Control Measures,
July 2002.
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Extended Detention Basin TC-22
Design Considerations
• Tributary Area
• Area Required
• MydraulicHead
Description
Dry extended detention ponds (a.k.a. dry ponds, extended
detention basins, detention ponds, extended detention ponds)
are basins whose outlets have been designed to detain the
stormwater ranoff from a water quality design storm for some
minimum time (e.g., 48 hours) to allow particles and associated
pollutants to settle. Unlike wet ponds, these facilities do not have
a large permanent pool. They can also be used to provide flood
control by including additional flood detention storage.
Caiifornia Experience
Caltrans constracted and monitored 5 extended detention basins
in southern California with design drain times of 72 hours. Four
ofthe basins were earthen, less costiy and had substantially
better load reduction because of infiltration that occurred, than
the concrete basin. The Caltrans study reaffirmed the flexibiUty
and performance of this conventional technology. The small
headloss and few siting constraints suggest that these devices are
one ofthe most applicable technologies for stormwater
freatment.
Advantages
• Due to the simpUcity of design, extended detention basins are
relatively easy and inexpensive to constract and operate.
• Extended detention basins can provide substantial capture of
sediment and the toxics fraction associated with particulates.
• Widespread appUcation with sufficient capture volume can
provide significant control of channel erosion and enlargement
caused by changes to flow frequency relationships resulting
from the increase of impervious cover in a watershed.
Targeted Constituents
• Sediment A
Nutrients •
• Trash • • Metals A
• Bacteria A
• Oil and Grease A
• Organics A
Legend (Removal Efhctiveness)
• Low • High
A Medium
Caiifomla
Stormwater
Quaiity
Association
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TC-22 Extended Detention Basin
Limitations
• Limitation of the diameter of the orifice may not allow use of extended detention in
watersheds of less than 5 acres (would require an orifice with a diameter of less than 0.5
inches that would be prone to clogging).
• Dry extended detention ponds have only moderate pollutant removal when compared to
some other stractural stormwater practices, and they are relatively ineffective at removing
soluble pollutants.
• Although wet ponds can increase property values, dry ponds can actuaUy detract from the
value of a home due to the adverse aesthetics of dry, bare areas and inlet and outlet
stractures.
Design and Sizing Guidelines
• Capture volume determined by local requirements or sized to treat 85% of the annual runoff
volume.
• Outiet designed to discharge the capture volume over a period of hours.
• Length to width ratio of at least 1.5:1 where feasible.
• Basin depths optimally range from 2 to 5 feet.
• Include energy dissipation in the inlet design to reduce resuspension of accumulated
sediment.
• A maintenance ramp ahd perimeter access should be included in the design to facilitate
access to the basin for maintenance activities and for vector surveillance and control.
• Use a draw down time of 48 hours in most areas of Califomia. Draw down times in excess of
48 hours may result in vector breeding, and should be used only after coordination with
local vector control authorities. Draw down times of less than 48 hours should be limited to
BMP drainage areas with coarse soils that readily settle and to watersheds where warming
may be determined to downstream fisheries.
Construction/Inspection Considerations
• Inspect facility after first large to storm to determine whether the desired residence time has
been achieved.
• When constracted with small tributary area, orifice sizing is critical and inspection should
verify that flow through additional openings such as bolt holes does not occur.
Performance
One objective of stormwater management practices can be to reduce the flood hazard associated
with large storm events by reducing the peak flow associated with these storms. Dry extended
detention basins can easily be designed for flood control, and this is actually the primary
purpose of most detention ponds.
Dry extended detention basins provide moderate pollutant removal, provided that the
recommended design features are incorporated. Although they can be effective at removing
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Extended Detention Basin TC-22
some pollutants through settiing, they are less effective at removing soluble poUutants because
of the absence of a permanent pool. Several studies are available on the effectiveness of dry
extended detention ponds including one recentiy concluded by Caltrans (2002).
The load reduction is greater than the concentration reduction because of the substantial
infiltration that occurs. Although the infiltration of stormwater is clearly beneficial to surface
receiving waters, there is the potential for groundwater contamination. Previous research on the
effects of incidental infiltration on groundwater quality indicated that the risk of contamination
is minimal.
There were substantial differences in the amount of infiltration that were observed in the
earthen basins during the Caltrans study. On average, approximately 40 percent of the ranoff
entering the unlined basins infilfrated and was not discharged. The percentage ranged from a
high of about 60 percent to a low of only about 8 percent for the different facilities. CUmatic
conditions and local water table elevation are likely the principal causes of this difference. The
least infiltration occurred at a site located on the coast where humidity is higher and the basin
invert is within a few meters of sea level. Conversely, the most infilfration occurred at a facility
located weU inland in Los Angeles County where the climate is much warmer and the humidity
is less, resulting in lower soil moisture content in the basin floor at the beginning of stortns.
Vegetated detention basins appear to have greater poUutant removal than concrete basins. In
the Caltrans study, the concrete basin exported sediment and associated pollutants during a
number of storms. Export was not as common in the earthen basins, where the vegetation
appeared to help stabilize the retained sediment.
Siting Criteria
Dry extended detention ponds are among the most widely applicable stormwater management
practices and are especially useful in retrofit situations wher6 their low hydraulic head
requirements aUow thera to be sited within the consttaints of the existing storm drain system. In
addition, many communities have detention basins designed for flood control. It is possible to
modify these facilities to incorporate features that provide water quality tteatment and/or
channel protection. Although dry extended detention ponds can be applied rather broadly;
designers need to ensure that they are feasible at the site in question. This section provides
basic guidelines for siting dry extended detention ponds;
In general, dry extended detention ponds should be used on sites wifh a minimum area of 5
acres. With this size catchment area, the orifice size can be on the order of 0.5 inches. On
smaller sites, it can be chaUenging to provide channel or water quality control because the
orifice diameter at the outiet needed to control relatively small storms becomes very small and
thus prone'^W8^^|ii|! adcfition, it is generally more cost-effective to control larger drainage
areas due to the economies of scale.
Extended detention basins can be used with almost aU soils and geology, with minor design
adjustments for regions of rapidly percolating soils such as sand. In these areas, extended
detention ponds may need an impermeable liner to prevent ground water contamination.
The base of the extended detention facility should not intiersect the water table. A permanently
wet bottom may become a mosquito breeding ground. Research in Southwest Florida (Santana
et al., 1994) demonstrated that intermittently flooded systems, such as dry extended detention
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TC-22 Extended Detention Basin
ponds, produce more mosquitoes than other pond systems, particularly when the facilities
remained wet for more than 3 days following heavy rainfall.
A study in Prince George's County, Maryland, found that stormwater management practices can
increase stteam temperatures (GalU, 1990). Overall, dry extended detention ponds increased
temperature by about 5°F, In cold water streams, dry ponds should be designed to detain
stomiwater for a relatively short time (i.e., 24 hours) to minimize the amount of waraimg fhat
occurs in the basin.
Additional Design Guidelines
In order to enhance the effectiveness of extended detention basins, the dimensions of the basin
must be sized appropriately. Merely providing the required storage volume will not ensure
maximum constituent removal. By effectively configuring the basin, the designer will create a
long flow path, promote the establishment of low velocities, and avoid having stagnant areas of
the basin. To promote settling and to attain an appealing environment, the design of the basin
should consider the length to width ratio, cross-sectional areas, basin slopes and pond
configuration, and aesthetics (Young et al., 1996).
Energy dissipation stractures should be included for the basin inlet to prevent resuspension of
accumulated sediment. The use of stilling basins for this purpose should be avoided because the
standing water provides a breeding area for mosquitoes.
Extended detention facilities should be sized to completely capture the water quality volume. A
micropool is often recommended for inclusion in the design and one is shown in the schematic
diagram. These small permanent pools greatly increase the potential for mosquito breeding and
complicate maintenance activities; consequentiy, they are not recommended for use in
California.
A large aspect ratio may improve the performance of detention basins; consequentiy, the outiets
should be placed to maximize the flowpath through the facility. The ratio of flowpath length to
width from the inlet to the outiet
should be at least 1.5:1 (L:W)
where feasible. Basin depths
optimally range from 2 to 5 feet.
The facility's drawdown time
should be regulated by an orifice
or weir. In general, the outflow
stracture should have a trash
rack or other acceptable means
of preventing clogging at the
entrance to the outflow pipes.
The outlet design implemented
by Caltrans in the facilities
constracted in San Diego County
used an outlet riser with orifices
sized to discharge the water
quality volume, and the riser
overflow height was set to the design storm elevation. A stainless steel screen was placed
Figure 1
Example of Extended Detention Outiet Structure
il
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Extended Detention Basin TC-22
around the outiet riser to ensure that the orifices would not become clogged with debris. Sites
either used a separate riser or broad crested weir for overflow of ranoff for the 25 and greater
year storms. A picture of a typical outiet is presented in Figure 1.
The outflow stracture should be sized to aUow for complete drawdown ofthe water quality
volume in 72 hours. No more than 50% of the water quality volume should drain from the
facility within the first 24 hours. The outflow stracture can be fitted with a valve so that
discharge from the basin can be halted in case of an accidental spiU in the watershed.
Summary of Design Recommendations
(1) Facility Sizing - Hie required water quaUty volume is determined by local regulations
or the basin should be sized to capture and treat 85% oftiie annual ranoff volume.
See Section 5.5.1 of the handbook for a discussion of volume-based design.
Basin Configuration - A high aspect ratio may improve the performance of detention
basins; consequentiy, the outlets should be placed to maximize the flowpath through
the facility. The ratio of flowpath length to width from the inlet to the outiet should
be at least 1.5:1 (L:W). The flowpath lengtii is defined as the distance from the inlet
to the outiet as measured at the surface. The width is defined as the mean width of
the basin. Basin depths optimally range from 2 to 5 feet. The basin may include a
sediment forebay to provide the opportunity for larger particles to settle out.
A micropool should not be incorporated in the design because of vector concems. For
online facilities, the principal and emergency spiUways must be sized to provide 1.0
foot of freeboard during the 25-year event and to safely pass the flow from loo-year
storm.
(2) Pond Side Slopes - Side slopes of the pond should be 3:1 (H:V) or flatter for grass
stabilized slopes. Slopes steeper than 3:1 (H:V) must be stabUized with an
appropriate slope StabUization practice.
(3) Basin Lining - Basins must be constracted to prevent possible contamination of
groundwater below the facility.
(4) Basin Inlet - Energy dissipation is required at the basin inlet to reduce resuspension
of accumulated sediment and to reduce the tendency for short-circuiting.
(5) Outflow Stractiire - The faculty's drawdown time should be regulated by a gate valve
or orifice plate. In general, the outQow stracture should have a ttash rack or other
acceptable means of preventing clogging at the entrance to the outflow pipes.
The outflow stracture should be sized to allow for complete drawdown of the water
quality volume in 72 hours. No more than 50% ofthe water quality volume should
drain from the facility witiiin the first 24 hours. The outflow stracture should be
fitted with a valve so that discharge from the basin can be halted in case of an
accidental spUl in the watershed. This same valve also can be used to regulate the
rate of discharge from the basin.
The discharge through a control orifice is calculated from:
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TC-22 Extended Detention Basin
Q = CA(2gH-Ho)°-5
where: Q = discharge (ft3/s)
C = orifice coefficient
A = area of the orifice (ft^*)
g = gravitational constant (32.2)
H = water surface elevation (ft)
Ho= orifice elevation (ft)
Recommended values for C are 0.66 for thin materials and 0.80 when the material is
thicker than the orifice diameter. This equation can be implemented in spreadsheet
form with the pond stage/volume relationship to calculate dram time. To do this, use
the initial height of the water above the orifice for the water quality volume. Calculate
the discharge and assume that it remains constant for approximately 10 minutes.
Based on that discharge, estimate the total discharge during that interval and the
new elevation based on the stage volume relationship. Continue to iterate until H is
approximately equal to Ho. When using multiple orifices the discharge from each is
summed.
(6) Splitter Box - When the pond is designed as an offlme facUity, a splitter structure is
used to isolate the water quality volume. The splitter box, or other flow diverting
approach, should be designed to convey the 25-year storm event whUe providing at
least 1.0 foot of freeboard along pond side slopes.
(7) Erosion Protection at the OutfaU - For online facilities, special consideration should
be given to the facUity's outfaU location. Flared pipe end sections that discharge at or
near the stteam invert are preferred. The channel immediately below the pond
outfaU should be modified to confonn to natural dimensions, and Uned with large
stone riprap placed over fUter cloth. Energy dissipation may be required to reduce
flow velocities from the primary spUlway to non-erosive velocities.
(8) Safety Considerations - Safety is provided either by fencing of the facility or by
managing the contours of the pond to eliminate dropoffs and other hazards. Earthen
side slopes should not exceed 3:1 (HiV) and should terminate on a flat safety bench
area. Landscaping can be used to impede access to the facility. The primary spillway
opening must not permit access by small children. OutfaU pipes above 48 inches in
diameter should be fenced.
Maintenance
Routine maintenance activity is often thought to consist mostiy of sediment and ttash and
debris removal; however, these activities often constitute only a smaU fraction ofthe
maintenance hours. During a recent study by Caltrans, 72 hours of maintenance was performed
annually, but only a Uttie over 7 hours was spent on sediment and trash removal. The largest
recurring activity was vegetation management, routine mowing. The largest absolute number of
hours was associated with vector control because of mosquito breeding that occurred in the
stilling basins (example of standing water to be avoided) instaUed as energy dissipaters. In most
cases, basic housekeeping practices such as removal of debris accumulations and vegetation
management to ensure fhat the basin dewaters completely in 48-72 hours is sufficient to prevent
creating mosquito and other vector habitats.
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Extended Detention Basin TC-22
Consequentiy, maintenance costs should be estimated based primarily on the mowmg frequen<y
and the time required. Mowing should be done at least annually to avoid establishment of
woody vegetation, but may need to be perfonned much more frequentiy if aesthetics are an
important consideration.
Typical activities and frequencies include:
• Schedule semiannual inspection for the beginning and end of the wet season for standing
water, slope stabUity, sedhnent accumulation, ttash and debris, and presence of burrows.
• Remove accumulated ttash and debris in the basin and around the riser pipe during the
semiannual inspections. The frequency of this activity may be altered to meet specific site
conditions.
• Trim vegetation at the beginning and end of the wet season and inspect monthly to prevent
estabUshment of woody vegetation and for aesthetic and vector reasons.
• Remove accumulated sediment and regrade about every lo years or when the accumulated
sediment volume exceeds lo percent of the basin volume. Inspect the basin each year for
accumulated sediment volume.
Cost
Construction Cost
The constraction costs associated with extended detention basins vary considerably. One recent
study evaluated the cost of all pond systems (Brown and Schueler, 1997)- Adjusting for
inflation, the cost of dry extended detention ponds can be estimated with the equation:
C = 12.4V°
where: C = Constraction, design, and permitting cost, and
V = Volume (ft3).
Using this equation, typical constraction costs are:
$ 41,600 for a 1 acre-foot pond
$ 239,000 for a 10 acre-foot pond
$ 1,380,000 for a IOO acre-foot pond
Interestingly, these costs are generally slightiy higher than the predicted cost of wet ponds
(according to Brown and Schueler, 1997) on a cost per total volume basis, which highlights the
difficulty of developing reasonably accurate constraction estimates. In addition, a fypical facility
constracted by Caltrans cost about $160,000 with a capture volume of only 0.3 ac-ft.
An economic concem associated with dry ponds is that they might detract slightiy from the
value of adjacent properties. One study found that dry ponds can actually dettact from the
perceived value of homes adjacent to a dry pond by between 3 and 10 percent (Emmerling-
Dinovo, 1995)-
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TC-22 Extended Detention Basin
Maintenance Cost
For ponds, the annual cost of routine maintenance is typicaUy estimated at about 3 to 5 percent
oflhe constraction cost (EPA website). Altematively, a community can estimate the cost ofthe
maintenance activities outlined m the maintenance section. Table 1 presents the maintenance
costs estimated by Calttans based on their experience with five basins located in southem
Califomia. Again, it should be emphasized that the vast majority of hours are related to
vegetation management (mowing).
Table 1 Estimated Average Annual Maintenance Effort
Activity Labor Honrs Equipinent &
Material ($) Cost
Inspections 4 7 183
Maintenance 49 126 22S2
Vector Control 0 0 0
Administration 3 132
Materials 535 535
Total 56 $668 $3,138
References and Sources of Additional Information
Brown, W., and T. Schueler. 1997. iTie Economics of Stormwater BMPs in the Mid-Atlantic
Region. Prepared for Chesapeake Research Consortium. Edgewater, MD. Center for Watershed
Protection. EUicott City, MD.
Denver Urban Drainage and Flood Conttol District. 1992. Urban Storm Drainage Criteria
Manual—Volume 3: Best Management Practices. Denver, CO.
Emmerlmg-Dinovo, C. 1995. Stormwater Detention Basins and Residential Locational
Decisions. Miter jResources BuZZeftn 31(3^: 515-521
Galli, J. 1990. Thermal Impacts Associated with Urbanization and Stormwater Management
Best Management Practices. MetropoUtan Washington CouncU of Govemments. Prepared for
Maryland Department of the Environment, Baltimore, MD.
GKY, 1989, Outlet Hydraulics of Extended Detention Facilities for the Northem Virginia
Planning District Commission.
MacRae, C. 1996. Experience from Morphological Research on Canadian Stteams: Is Control of
tiie Two-Year Frequency Runoff Event the Best Basis for Stteam Channel Protection? In Effects
of Watershed Development and Management on Aquatic Ecosystems. American Society of
CivU Engineers. Edited by L. Roesner. Snowbird, UT. pp. 144-162.
Maryland Dept of the Environment, 2000, Maryland Stormwater Design Manual: Volumes 1 &
2, prepared by MDE and Center for Watershed Protection.
http://www.mde.state.md.us/environment/wma/stormwatermanual/indftx.html
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Extended Detention Basin TC-22
Metzger, M. E., D. F. Messer, C. L. Beitia, C. M. Myers, and V. L. Kramer. 2002. The Dark Side
Of Stormwater Runoff Management: Disease Vectors Associated With Stractural BMPs.
Stormwater 3(2): 24-39.
Santana, F., J. Wood, R. Parsons, and S. Chamberlain. 1994. Control of Mosquito Breeding in
Permitted Stormwater Systems. Prepared for Southwest Florida Water Management District,
BrooksviUe, FL.
Schueler, T. 1997. Influence of Groundwater on Performance of Stormwater Ponds in Florida.
Watershed Protection rechniques 2(43:525-528.
Watershed Management Institute (WMI). 1997. Operation, Maintenance, and Management of
Stormwater Management Systems. Prepared for U.S. Environmental Protection Agency, Office
of Water. Washington, DC.
Young, G.K., et al., 1996, Evaluation and Management of Highway Runoff Water Quality,
Publication No. FHWA-PD-96-032, U.S. Department of Transportation, Federal Highway
Administtation, Office of Environment and Planning.
Iitformation Resources
Center for Watershed Protection (CWP), Environmental Quality Resources, and Loiederman
Associates. 1997. Maryland Stormwater Design Manual. Draft. Prepared for Maryland
Department of the Environment, Baltimore, MD.
Center for Watershed Protection (CWP). 1997. Stormwater BMP Design Supplement for Cold
Climates. Prepared for U.S. Environmental Protection Agency, Office of Wetiands, Oceans and
Watersheds. Washington, DC.
U.S. Environmental Protection Agency (USEPA). 1993. Guidance Specifying Management
Measures for Sources of Nonpoint Pollution in Coastal Waters. EPA-840-B-92-002. U.S.
Envfronmental Protection Agency, Office of Water, Washington, DC.
January 2003 California Stonmwater BMP Handbook 9 of 10
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TC-22 Extended Detention Basin
MAXIMUM ELEVATIOI
OF SAFETY STORM
MAXIMUM ELEVATION
OF ED POOL
SAFETY-
BENCH
EMERGENCY
SPa.LV«AY
PLAN VIEW
\7100 YEAR LEVEL
EMBANKME^fr-
RISER-
ANTI-SEEP COLLAR or -
FILTER DIAPHRAGM
EMERQENCY
SPILLWAY
PROFILE
Schematic of an Extended Detention Basin (MDE, 2000)
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Drain Inserts MP-52
Description
Drain inserts are manufactured filters or fabric placed in a drop
inlet to remove sediment and debris. There are a multitude of
inserts of various shapes and configurations, typically falUng into
one of three different groups: socks, boxes, and trays. The sock
consists of a fabric, usually constracted of polypropylene. The
fabric may be attached to a frame or the grate of the inlet holds
the sock. Socks are meant for vertical (drop) inlets. Boxes are
constracted of plastic or wire mesh. Typically a polypropylene
"bag" is placed in the wire mesh box. The bag takes the form of
the box. Most box products are one box; that is, the setting area
and filtration through media occur in the same box. Some
products consist of one or more trays or mesh grates. The trays
may hold different types of media. Filtration media vary by
manufacturer. Types include polypropylene, porous polymer,
treated cellulose, and activated carbon.
California Experience
The number of installations is unknown but likely exceeds a
thousand. Some users have reported that these systems require
considerable maintenance to prevent plugging and bypass.
Advantages
• Does not require additional space as inserts as the drain
inlets are already a component of the standard drainage
systems.
• Easy access for inspection and maintenance.
• As there is no standing water, there is little concern for
mosquito breeding.
• A relatively inexpensive retrofit option.
Limitations
Performance is likely significantiy less than treatment systems
that are located at the end of the drainage system such as ponds
and vaults. UsuaUy not suitable for large areas or areas with
trash or leaves than can plug the insert.
Design and Sizing Guidelines
Refer to manufacturer's guidelines. Drain inserts come any
many configurations but can be placed into three general groups:
socks, boxes, and ttays. The sock consists of a fabric, usually
constracted of polypropylene. The fabric may be attached to a
frame or the grate of the inlet holds the sock. Socks are meant
for vertical (drop) inlets. Boxes are constracted of plastic or wire
mesh. Typically a polypropylene "bag" is placed in the wire mesh
box. The bag takes the form of the box. Most box products are
Design Considerations
• Use with other BMPs
• Fit and Seal Capacity within Inlet
Targeted Constituents
</ Sediment
/ Nutrients
/ Trash
V Metals
Bacteria
/ Oil and Grease
/ Organics
Removal Effec^veness
See New Development and
Redevelopment Handbook-Section 5.
AC ASQA
Icalifomia
Stormwater
Quality
Association
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MP-52 Drain Inserts
one box; that is, the setting area and filtration through media occurs in the same box. One
manufacturer has a double-box. Stonnwater enters the first box where setting occurs. The
stormwater flows into the second box where the filter media is located. Some products consist
of one or more ttays or mesh grates. The trays can hold different types of media. Filtration
media vary with the manufacturer: types include polypropylene, porous polymer, treated
cellulose, and activated carbon.
Construction/Inspection Considerations
Be certain that instaUation is done in a manner that makes certain that the stormwater enters
the unit and does not leak around the perimeter. Leakage between the frame of the insert and
the frame of the drain inlet can easily occur with vertical (drop) inlets.
Performance
Few products have performance data collected under field conditions.
Siting Criteria
It is recommended that inserts be used only for retrofit situations or as pretreatment where
other treatment BMPs presented in this section area used.
Additional Design Guidelines
Follow guidelines provided by individual manufacturers.
Maintenance
Likely require frequent maintenance, on the order of several times per year.
Cost
• The initial cost of individual inserts ranges from less than $100 to about $2,000. The cost of
using multiple units in curb inlet drains varies with the size of the inlet.
• The low cost of inserts may tend to favor the use of these systems over other, more effective
treatment BMPs. However, the low cost of each unit may be offset by the number of units
that are required, more frequent maintenance, and the shorter stractural life (and therefore
replacement).
References and Sources of Additional Information
Hrachovec, R., and G. Minton, 2001, Field testing of a sock-type catch basin insert. Planet CPR,
Seattie, Washington
Interagency Catch Basin Insert Committee, Evaluation of Commercially-AvaUable Catch Basin
Inserts for the Treatment of Stormwater Runoff from Developed Sites, 1995
Larry Walker Associates, June 1998, NDMP Inlet/In-Line Control Measure Study Report
Manufacturers literature
Santa Monica (City), Santa Monica Bay Municipal Stormwater/Urban Runoff Project -
Evaluation of Potential Catch basin Retrofits, Woodward Clyde, September 24,1998
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Drain Inserts MP-52
Woodward Clyde, June ii, 1996, Parking Lot Monitoring Report, Santa Clara Valley Nonpoint
Source PoUution Control Program.
January 2003 Califomia Stormwater BMP Handbook 3 of 3
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BIO CLEAN
ENVIRONMENTAL SERVICES, INC.
Grate Inlet Skimmer Box
Curb Inlet Basket
Nutrient Separating Baffle Box
REPORTS & DATA
Pollutant Loading Analysis for Stomiwater Retrofitting in
Melboume Beach, Florida
Pollutant Removal Testing for A Suntree Technologies Grate
Inlet SIdmmer Box
Site Evaluation of Suntree Technologies, Inc Grate Inlet
Skimmer Boxes for Debris, Sediment And Oil & Grease
Removal
BiO CLEAN ENVIRONIVIENTAL SERVICES, INC.
P O BOX 869, OCEANSIDE, CA 92049
(760) 433-7640 FAX (760) 433-3176
Pollutant Loading Analysis For Stomiwater Retrofitting in Melboume Beach,
Florida
By: Gordon England, P.£.
Creech Engineers, Inc
4450 W. Eau GaUie Blvd, #232
Melbourne, FI. 32932
Introduction
At Gemini Elementary School in Melboume Beach, Florida, there has been a history of
repeated flooding on the school grounds and in properties adjacent to the school. In
1999 Creech Engineers, Inc. (CEI) was chosen by Brevard County Stormwater UtiUty to
design drainage in^)rovements to aUeviate these flooding conditions, as weU as to
provide for stormwater tteatment within this 20.06 hectare drainage basin. The project
was divided into two phases. Phase 1 improvements were made in order to accelerate
initial flood control measures for homes downstream ofthe schooL Phase 2 involved the
design of more extensive flood and water quality control measures along Oak Street for
further protection of school property and roadway flooding at nearby church property.
This paper highlights the poUtical chaUenges of retrofitting stormwater systems in
developed areas, as weU as demonstrates a methodology for pCTforming a nonpoint
source poUutant loading analysis.
Existing Conditions
Genuni Elementary School is located on a 8.02 hectare, triangular shaped property along
the south side of Oak Street, a two lane coUector road in Melboume Beach, about one
half mUe from the Atlantic Ocean. See Exhibit 1. Residential properties Ue downsfream
ofthe school, along its southeast and southwest borda:^. 8.51 hectare Doug Flutie Park is
on tiie nortii skle of Oak Stteet A soccer chib uses the park and school grounds on a daUy
basis. There was no stoimwater system at the park, abng Oak Street, or on the school
site. Stormwater flowed southward ofi" Doug Fhitie Park, across Oak Sfreet, through the
school site, and into the yards and homes south ofthe schooL These yards, and the roads
downstream of them, are very flat and only a few feet above sea leveL Once water stages
high enough in tiie yards, it graduaUy sheetflows down the adjacent roads a few hundred
yards to the Indian River. The affected homeowners naturaUy blamed the school for
aUowing the school's water to flood them.
West ofthe school, a few hundred yards atong Oak Stteet, was a tow point in tiie road
where water ponded and flooded the road and an adjacent churchyaid. Due to a thin clay
lens at 26 cm deep causing a perched water tabte, water stood in the road for several days
after even a nominal rainfall. This drarnage basin was ahnost con^letely built out, with
no easy path for developing outMs to reUeve flooding.
This section of the Indian River is a Class 2 water body, with a SheUfish Harvesting
classification bringing intense scmtiny from the St Johns River Water Management
District. Corp of Engineers permitting is required for new out&lls in the area due to
seagrasses near the shoreUne.
The park, the school, and Oak Street Ue in unincorporated Brevard County. The church,
and properties west of the school are in Melboume Beach. Being a coUector road, all of
the UtUity con4)anies have major transmission Unes in the road r^ht-of-way.
As can be seen, this chaUenging project involved Brevard County, Melboume Beach, the
School Board, Brevard County Parks and Recreatton Department, Brevard County Road
and Bridge Departn^t, Brevard County Stonnwater UtUity, a church, three different
Homeowners Associations, a soccer club, the Water Mtaiagement District, the Corp of
Engineers, and several utUity conipanies. Stakeholdo- involvement and partnerships were
going to be critical to weave a solution throi^h the many players involved.
Proposed Improvements
The first priority was to aUeviate flooding in the homes adjacent to the schooL As an
interim measure, a berm was desigii and constructed by County personnel along the
soutii property lines of the school, with a swate behind the berm directii^ water to the
southernmost point of the school property. At that tocation, an inlet and 18" out&ll pipe
were constructed in a utiUty easement through two heavUy landscaped and fenced yards,
to Ponpano Stteet, where it was tied into an existing storm drain pipe.
A short time later, heavy rains overflowed the bmos and swales and flooded homes
adjacent to the school again. CEI was engaged at that point to piovkto more eflective
drainage improvements.
Fortunately, Gemini Elementary School had a signiflcant ai«a of vacant land on their site.
The school entered into agreements with Brevard Coimty altowing the constraction of
three dry retention ponds totaling 2.95 hectare to reduce flows leaving the school site, as
weU as provkle stormwater treatinent w*ere none existed. These dry ponds were wound
around several soccer and basebaU fields. The soccer field's tocattons had to remain in
place due to previous agreements with the school and Parks and Recreation Dept. The
ponds were only 26-40 cm (12"-18") deep and sodded, aUovwng the soccer teams to use
the pond areas as practice fields when dry. When the ponds were excavated, the
confining clay layer was removed to aUow for infiltration though the beach sand at the
site. Constmctton was scheduled during the summer when school was out.
A control stractiire was designed at the outfaU pipe locatton to piovide protection for a 25
year storm The temporary connection to the existing downstieam pipe had overloaded
the downstream system in a heavy rain event, so a new outfeU to the Indian River was
designed through a park adjacent to the River. The park was owned by a Homeowners
Association, which reluctantly gave a drainage easement thiough tiie park. The County
agreed to make several inprovements to the park and its boat rsoDp in exchange for the
easement. The Corp of Engineers was concemed that the new outfeU pipe discharges
would unpact the nearby seagrasses, so the new discharge pipe was not permitted to be
wnstracted m the Indian River. A bubbleup box was designed ten feet back fiom tiie
ShoreUne and rock riprap was placed between the bubbleup box and tiie mean high water
line to prevent erosion. As mitigation for disturbmg the shoreUne, spartina and otiier
plants were planted among tiie rocks to fiirther buffer tiie shoreUne fiom tiie stonnwater
discharges.
This first phase of improvements was finished in September 2000 at a cost of $124 000
The unprovements inqilemented proved successfiil in preventing any flooding of adj^ent
homes m several large rainfeUs in 2001.
The second phase of tiie pioject addressed stomiwater quantity and quaUty concems
along 1650 meters of Oak Stteet, fix)m AIA to Cheny Stteet. To piovkle fiirther flood
^ ^^^^ School, retaition swales were designed along botii sides
of Oak Stt^ and 625 meters of stonn drain pipe was designed to intercept ninoff and
^'!Sf/ ^ P'^P^rty- The piping also provided an outM for tiie tow spot m the road by the church.
This new pipe system discharged into a residential canal system, which was used by
many of tiie adjacent residents for boating to tiie Indian River Lagoon (Bay) These
CMials were very poUtically sensitive since they were in need of dredging and tiie Town
of Melboume Beach does not dredge canals. The residents were concemed tiiat tiie new
stoimwater system would lead to fiuther sedimentation oftiie canals. The first alternative
for freafrnent was to use land at tiie church site for a pond for tiie road ninoff. The church
was willmg to donate tiie land where tiieir septto tank fields were located if tiie County
would provide a sewer comiection. This scenario was designed, but when it came time
for tiie church to give easements to tiie County, they baUced and it was back to the
drawmg board.
frL^^-^' ^^^"^ Man^ement Distttot, (Disfrtot), criteria requires stomiwater
2^ T^^r^"^ ^^'^^ *>) which hicrease poUutant
loadmgs. or c) which mcrease mipervtous areas. With this project, no new tocreased
impervious areas were proposed, but tiiere wouki be addittonal water flowimj to tiie
residential canal fiom tiie extenston of tiie p^ system to tiie flood prone a^ TiZ
design metiKj^woiUd tow
to lack of a>^ble land for ponds, alt«native tteatment metiiods were pro^ for^
demonsttated ttot aU otiier possibte altematives tove been extousted. It would^t to
^^Jl'^f ? or paric area for tteatinent ponds. ForS proLv
CEI showed tiiat tiie only altematives were to tear down ho^ for^ndT ^ S
alternate treatment technotogies. ^ ' ^
The treatment sfrategy involved maximizing treatment methods within the project basin
with altemative BMPs, as weU as retrofitting two adjacent watersheds as additional
mitigation. A total of 1.67 acre feet of retentton storage was provkied in Phase 2 in tto
roadside swales ami smaU ponds. This was equivalent to 0.032 inctos of retentton from
the drainage areas flowing to tto retention areas.
A tteatment frain atong Oak Street was designed by using 9 Grated Intet Skimmer Boxes,
from Suntree Technotogies, Inc., in tto new inlets to trap debns entering the inlets,
constmcting tonus to slow runoff from tto ball fields, and instaUing one toffle hox at the
downstteam end of the new pipe system along Oak Street Baffle Boxes are in-line
stormwater tieatment devices whtoh tr^ sediment, trash, and debris. Ttoy tove been
used by Brevard County successfoUy for tto last 9 years. In offeite Basin 4, which only
had one existing toffle tox to provide sedhnent removal, 16 Curb Inlet Skimmer Boxes
were instaUed in all of tto existing inlets to provide nutrient removal by trapping grass
cUppmgs, teaves, and yard debris. Nutrients were a concem in tto canals smce tto
nutrients promote algae blooms, which m tum increase muck buUd up in tto canals. In
offsite drauiage Basin 5, there are 3 existing pipes which discharge directiy to the canals.
Three baffle toxes and 6 curb inlet skimmer toxes were designed to provide sediment
and nutrient treatment for this drainage basin. Brevaid County Stoimwater Utility wiU
implement this project and to responsible for aU maintenance of tto inprovements. Tto
baffle toxes wUl to inspected twtoe a year and cleaned as needed. Tto inlet traps wiU to
cleaned twice a year. Brevard County has a vacuum tiuck dedicated to cleaning
stonnwater BMPs.
Using numerous BMPs used on this project provided a high degree of treatment for the
new pipmg system along Oak Sfreet, and provided freafrnent for two offsite basms where
little treatinent existed. The rehofittmg oftiie offsite areas was, in effect, mitigation for
tiie new discharges to tiie canal. See Exhibit 1 for a map oftiie improvements.
Calculations
In Ptose 1 oftiie project, tto diy ponds and outfeU pipes were modeled hydrauUcally
using tto Interconnected Pond Routing program. Since the dry ponds in the Phase 2
project area were too smaU to provide effective attenuation, tiie predevelopment and post
development runoff calculations were made using Hydraflow and tiie lational mettod
The only available storm drain pipe for Phase 2 was a 36" pipe in offeite Basin 4. The
new pipmg along Oak Stieet was connected to tiie existing 36" pipe, and the piping
downstream oftiie connection was upgraded to a 42" ppe. The pipes were designed for
a 25 year stonn. Basins 1,2, and 3 were a much tonger distance from tiie outfaU tiian
Basm 4. As a result of different times of concentration, tiie peak flows from Basm 4
passed sooner tiian Basins 1,2, and 3, giving only a sUght increase in peak discharge,
despite adding 12.25 hectares to tiie area flowing to tto existing outfell.
The potential for increased poUutant loadings in tiie canal system was a concem of tocal
residents. These canals had a history of dredging operattons every 8-10 years, and tiie
residents did not want to mcrease tto frequency of costly dredging. Tto mam poUutants
of concem leading to muck depositton in tto canals were Total Suspended Solids (TSS),
Total Nitixigen (TN), and Total Phosptorus (TP). Sediment toUd up at tto end of the
pipes was common. Nutrient loadings fix>m grass clippings, leaves, and fertUizers leads
to algae blooms and tow dissolved oxygen in tto cmials, which in tum leads to muck
build up fixim tto eutrophtoation process. Most of tto material dredged from residential
canals is typically muck.
To address this concern, a poUutant toading analysis of tto existing and proposed
stormwater discharges was performed. In tto existing conditions, the only stormwater
treatment for tto canal system was a baffle tox along Cherry Stre^ for offeite Basin 4 of
24,24 hectares. Ttore were a total of 7 outfeU ppes discharging into tto canal system
In the first phase of this project stonnwater treatinent was pro\dded for 8.02 hectares of
tto school grounds witii 3 dry detention ponds. Tto discharge from ttose ponds was to
tto Indian River, rattor than tto canal system, so these poUutant toads were not included
m tto poUutant load analysis for tto canal outfeU.
The existing pollutant load to tto canal only came fixim tto drainage Basuis 4 and 5,
totaling 31.2 hectares. Tto runoff fiom Oak Street did not drain to tto canal in existing
condittons, only in tto post devetopment condittons.
The strategy for the poUutant analysis was to calculate tto poUutant toads in tto existing
conditions, and then calculate tto poUutant loads after tto new pipes were added to the
system and offeite areas retrofitted for stormwater treatment. Tto poUutants used in this
analysis were TSS, TP, and TN.
Each drainage tosin was categoricd by land use. Areal, annual, mass toading rates from
"Stoimwater Loading Rate Parametere for Cenfral and Soutii Florida", Haiper, 1994,
were multiplied by each basin's area to give existing and potential annual pollutant
loadings. See Table 1.
The next step was to calculate tto poUutant removal rates for tto different BMPs.
Individual BMP removal efficiencies were take from "A Guide for BMP Selectton in
Urban Developed Areas", EWRI, 2000. What was ctollenging wifli tiiis analysis was flie
use of multiple BMPs in series for tiie frieatment tram. Each BMP receives cteaner and
cleaner water as tto water moves down flie train. At each BMP, tiie removal efficiency
for each constituent was muItpUed by flie remaining percentage of tto initial toading to
give a weighted, cumulative, removal efBciency for each constitueitf. See Table 2.
These calculated removal efficiencies were tiien multiplied by tiie total calculated
poUutant toads to give the reduced poUutant toadings after the BMPs were instaUed. See
Table 3. Tabte 4 shows that the total toads to tto canal were reduced as a result of tto
retrofitting of onsite and offsite basins.
Tto pollutant loading analysis tolow demonstirates ttot as a result oftiie numerous BMPs
proposed, the total poUutant loadings entering tto canals after project completion wUl
actuaUy to significantly reduced from tto existing poUutant loadings entering the canals.
The key to overaU poUutant reduction is to provkte additional treatment in offeite
drainage basins. This will result in a net benefit of reduced poUutants entering the canals
and a reduction of the severe flooding often seen along Oak Street.
Tabie 1
Existing Pollutant Loading
Basin
Area
(acres) Land Use
Loading Rate*
(kg/ac - year)
Potential Pollutant Loading
(kg-year)
Basin
Area
(acres) Land Use TSS
Total
Phosphorus
Total
Nitrogen TSS
Total
Phosphorus
Total
Nitrogen
2A 9.23 RecreaUoned 7.6 0.046 1.07 70.15 0.425 9.876
2B 1.15 Recreattorari 7.6 0.046 1-07 8.74 0.053 1.231
2C 0.77 Recreattonai 7,6 0,046 1.07 5.85 0,035 0.824
2D 1.45 Recreattonal 7.6 0,046 1.07 11.02 0.067 1.552
2E 2.63 Recreaiional 7.6 0,046 1.07 19.99 0.121 2.814
2F 1.97 RecreaiHonad 7.6 0.046 1.07 14,97 0.091 2.108
2G 0.75 RecreaHonai 7,6 0,046 1.07 5.70 0.035 0.803
2H 1.29 Recreatkinsri 7,6 0,046 1.07 9.80 0.059 1.380
21 0.08 Recreattonal 7.6 0,046 1.07 0,61 0.004 0.086
2J 0.8 Recreationai 7.6 0.046 1.07 6.08 0.037 0.856
1 2K 0.57 Recreattorad 7.6 0.046 1.07 4.33 0.026 0.610
2L 0.34 Recreattonal 7.6 0,046 1.07 2.58 0.016 0.364
3A 2.19 Single Family 56.1 0,504 4.68 122.86 1.301 10.249
3B 3.02 Singie Family 56.1 0.594 4.68 169.42 1.794 14.134
30 4.02 Lew Intensity
Commercial 343 0,65 5.18 1378,86 2.613 20.824
Suiitotal 30.26 6.68 67.71
4** 59.9 Single FamOy 56.1 0,594 4.68 672.00 24.910 280.332
5A 5.9 Single Fainilv 56.1 0.594 4.68 330.99 3,505 27.612
5B 8.62 Single Famay 56.1 0,594 4.68 483.58 5.120 40.342
5C 2.68 Single Famly 56.1 0.594 4,68 150.35 1,502 12.542
Subtotal 77.1 1636.92 35.13 360.83
Totals 107.36 3467.89 4^M 428.54
* From "Stormwater Loading Rate Parameters for Central and South Florida", 1994. Harper
** Basin 4 has an existing baffle box providing treatment.
Basins 4 and 5 are the existing pollutant loadings to the canals.
Table 2
BMP PoUutant Removals
BMP POLLUTANT REMOVAL TABLE*
BMP BMP Removal Efficiency
Type (%)
TSS TP TN
Dry Pond 85 61 91
Swale 80 45 25
Baffle Box 80 30 0
inlet Trap (grated) 73** 79** 79**
Inl^ Trap (curb) 11*** 10***
Swale + Inlet Trap (g) + Baffle Box 98.9 91.9 84.2
Dry Pond + Intet Trap (g) * Bame BGK 99.2 94.3 98.1
Iniet Trap (c)+ Baffie Box 84 37.7 10
Inlet Trap (g)+ Baffie Box 81.1 85.3 79
Muitipie BMP PoUutant Removal Calculations
Swale + inlet Trap (g) + Baffle Box
TSS - 100x0.8 + (10O«))x0.73 + (10O«)-14.6)x0.8 = 98.9% Removal
TP - 100x0.45 + (100-45)x.79 + (100-4&-43.45) = 91.9% Removal
TN - 100X.25 + (10^25)x.79 = 84.2% Rernoval
Dry Pond + Inlet Trap (g) + Baffle Box
TSS - 100x0.85 + (100-85)x0.73 + (100^10.95)x0.8 = 99.2% Removal
TP - 100x0.61 + (100^1)x0.79 + (10O61-30.8)x.3 = 94.3% Removal
TN - IOOx.91 + (100-91)x.79 = 98.1% Removd
Iniet Ttap (c) + Baffle Box
TSS - 100-X0.2 + (100-20)x0.8 = 84% Removal
TP - 100x0.11 + (100-11)x.3= 37.7% Removal
TN - IOOx.10 = 10% Removal
Inlet Trap (g) + Baffle Box
TSS - 100x0.73 + (100-73)x0.30 = 81.1% Removai
TP - 100x0.79 + (100-79)x0.3 = 85.3% Removal
TN - IOOx.79 = 79% Removal
All removal values are from "Ginde For Best ItAanagement Practice
** From Creech Engineers study "Pollutsmt Removal Testing For a Suntree Technologies Grate
Inlet Skimmer Box", 2001
***From visual obsen/ation by Brevard County staff
Tabte 3
Proposed Pollutant Loading
Basin BMP
Type
BMP Removal
Efficiency
From New BMPs
(%)
Pdiulant Load
Reduction
From BMPs (icgfyear)
Proposed Pollutant
Loading (kg/Vear)
TSS TP TN TSS TP TN TSS TP TN
2A swale + Met trap (a)baffle box 96.9 91.9 84.2 ease 0.39 8.32 a77 0.03 1.56
2B swate«-intat trap (g) ••• baffle box 98.9 91.9 84.2 8.64 aos 1.04 0.10 0.00 ai9
2C dry pond ••• Met trap (0)baffle box 99? 94.3 9ai 5.81 ao3 0.81 aos aoo 0.02
2D dry pond+Met trap (g)« baffle box 99L2 94.3 gai lags ao6 1.52 ao9 aoo 0.03
2E dry pond + Met trap (g) + baffle box 9S2 94.3 g&i 19.83 0.11 2.76 ai6 0.01 0.05
2F swsle + Met trap (Sd + baffle box ga9 91.9 84.2 14.81 aoe 1.77 ai6 aoi 0.33
2G dry pondMet trap (g)baffle box 94.3 98.1 5.65 0.03 0.79 0.05 0.00 0.02
2H dry pond Met trap (g) + baffle box 99.2 94.3 96.1 9.73 ao6 1.35 0.08 0.00 0.03
21 swaie-t-Met trap (g)baffle box 96.9 91.9 84.2 0.60 0.00 0.07 aoi 0.00 0.01
2J Met trap (g) •!• baffle box 81-1 85.3 79 4.93 ao3 0.68 1.15 0.01 ai8
2K Met trap (Qd baffle box 81.1 85.3 79 3.51 0.02 0.48 0.82 0.00 0.13
2L Met trap (g) baffle bcK 81.1 85.3 T9 Z1Q aoi 0.29 0.49 aoo 0.08
3A Met trap (fl) baffle box 81.1 86.3 79 99.64 1.11 8.10 23.22 ai9 i15
38 Met trap (g) * baffle box 81.1 8S.3 79 137.40 1.53 11.17 32.02 0.26 2.97
3C diy pond + Met trap (g) + baffle box 99.2 94.3 96.1 1367.83 2.46 20.43 11.03 ai5 0.40
4 Met trap (g) + baffle box 81.1 86.3 79 544.99 21.25 221.46 127.01 3.66 58.87
SA Met trap (c) + baffle box 84 37 10 278.03 1.30 2.76 52.96 2.21 24.85
SB Met trap (c) ••• tnffle box 84 37 10 406.21 1.89 4.03 77.37 3J23 3&31
5C Met trap (c) + bafHe box \
84 37 10 126L29 0.59 1J25 24.06 1.00 11.29
ToUri 2305.77 27.24 281.03 197.19 4.34 67.01
Tabte 4
Net Pollutant Removals
TSS (ke/yr) TP(kg^r) TN(k}s/yr)
Predevelopment 3015,78 35.13 380.83
Postdevelopment 630,97 21.95 289.15
Net Reduction 2384,81 (79%) 13,18(37.52%) 91.68(24,07%)
Summary
The days of solving flooding probtems in communities with sunple ditch and pipe
solutions tove disappeared. Environmental concems now dictate ttot stonnwater
treatment techniques to integrated into these flood reUef projects. By adding water
quality conponents to water quantity projects, communittes can tolp achieve poUution
remediatton goals toing estabUshed for NPDES, TMDL, and PLRG programs.
Retrofitting existing stormwater systems to provide water quaUty treatment is more
complicated, expensive, and tin^ consuming than tradittonal stormwater designs for new
development. The scarcity of availabte land and numerous existmg utUities m older built
out areas wiU tax an engineer's imagination to provkie innovative BMPs in these
locations. An carefiilly planned tre^ment train was designed consisting of swales, ponds,
berms, baffle toxes, and inlet fr^ips tq provide overaU stonnwater poUution reduction.
In order to address stormwater poUution concems, treatment mitigation was designed in
offsite drarnage basins. Tto poUutant loadmgs aiKl removals were calculated using a
simple but effective spreadsheet analysis incoiporating tto latest in BMP efficiency
studfes. WhUe complicated stonnwater modeUng software can to used for pollutant
analysis, tiiis type of modeling is more cost eflfective on large basin studies than smaU
tosins and individual projects, Tto poUutant removal calculations stowed an annual net
reduction of 79% for TSS, 37% for Total Ptosptonis, and 24% for Total Nifrogen in tto
Oak Street basin despite the creation of a new stormdrain system for a landlocked area.
As this project demonstirates, ttore are typicaUy numerous stakehoWere ttot need to to
brought into the project early m tto process and kept m tiie process througtout flie life of
the project. Many meetings were told with city, county, and state offtoials, tomeowners
associations, schools, soccer clubs, churches, and utiUty conpanies. All it takes is one
uncooperative staketolder to set back or kUl a project, as was demonsttated with tiie
church backmg out of the land acquis^ion process after many verbal indications of
approvaL Using creative parfrierships vwth other entitfes and agencies allowed the
development ofa unique sfrategy to solve flooding at several tocations in tto project area.
References
ASCE - "Guide For Best Management Practice Selectton in Urban Developed Areas"
2001
Gordon England, P.E. "PoUutant Removal Testmg For a Suntree Tectoologies Grate
Inlet Skimmer Box", 2001
Harvey Harper, Ph. D, P,E„ "Stormwater Loading Rate Parameters for Central and
South Ftorida", 1994
POLLUTANT REMOVAL TESTING
FOR A SUNTREE TECHNOLOGIES
GRATE INLET SKIMMER BOX
'''lir'^^irTrffi rTfy-i'iT t;fff^iSWiMiiffiin
Prepared for
Suntree Technologies, Inc.
November 2001
CEI Project #21121.00
Prepared By:
4450 W. Eau Gallie Blvd., Ste. 232
Melbourne, FL 32934
(321) 255-5434
PAGE
Background 1
Methodology 2
Results 2
Table 1 - Sediment Sieve Analysis 3
Conclusions 3
APPENDIXA
> SKs Photos
APPENDIX B
> Universal Engineering Sciences Grate inlet Skimmer Box
Evaluation Report
Pollutant Removal Testing for a Suntree Technologies
Grate Inlet Skimmer Box
by
Creech Engineers, Inc
November 2001
With special thanks to Joanie Regan ofthe Cocoa Beach Stormwater UtiUty
Backaround;
Over tiie last several years, a nuniber of BMPs tove been devetoped to provkte
stonnwater freatment fay ttapping poUutants and debris in intets. Intet trap BMPs are
quasi source controls, benig ineiqiensne, requiring no roadway constmctton or utiUty
retocatton, and keeping poUutants out of AK water bodtos, ladier flian trying to remove
flie poUutants fiom fbc water mice it is contaminated. Suntiee Tecfanotogtes, of Cape
Canaveral, Ftorida conmusstoned Creech Engineeis, Inc. and Universal Ei«ineering to
peiform testing on a Grate Intet SkmmRr Box (CHSB) to detemme its poUutant removal
effectiveness for sediment and grass cuppings. Tto testing was perionned on Sefitember
26, 2001. Attadied are i^togn^dis fiom tto test and tto accompanying report by
Universal Engmeoring Sciences.
Tto GISB is designed to trap sedhnent, grass, leaves, organte debris, floatmg trash, and
Mrocartons as tiKy enter a grated intet, fliereby preventmg these poUutants fiom
entering flie stonndram system where ttoy wouki cause detrimental unpacts on
downstream wateibodies. Tto (HSB is a 3/16" flitok fiberghss device custom made to fit
most types of grated mtets. Tto oveiflow capacity of flie CHSB is designed to to greater
flian tto curb grate capacity, therein msuriog flat tiiere witt to no toss of Iqrdraulto
capacity due to tfie devfce tomg mskte flie mtet. Tte tottom of tte GISB is designed to
to atove any pipes entering or feavmg tiie mtet so fliat flow throng flie mtet is not
btocked.
Water flowmg flirough flie grate first encounters a hydrocaiton absorbing ceUutose. This
boom also serves to trap hn^ debris between flie boom and tte bo<fy of flie GISB. At flie
tottom of tiie frap are a series of sUiintess steel filter screens covering 3.5 inch wkie
cutouts in flie fiberglass body. These screens txap debris white aUowmg water to pass
flirough tiie tottom of tfie bo<fy and out to tfie stonn dram system. Tto screens in tiie
floor and fiistvertfcal row oftfie GISB arc fine mesh. Tto second vettical row of screens
are medhnn mesh and tiie highest row are coarse mesh. On flie outskte of tfie cutouts
tfie screens are backed fay stainless diamond plate to provkte sappoit to tfie screens since
heavy toads of debris bufld up in tfie tox. If tfie flow rate tfirough tfie mtet exceeds tfie
capacity of tfie filter screens ttore is anotfier row of overflow totes cut out wifli no
screens. These overflow totes aUow water to pass flirough flie GISB even if it becomes
fiiU of debris, Tto level of tfie totes is atove tfie tottom oftfie top Hay, enabUng tfie ttay
to act as a skimmer to prevent floating ttash ftom escaping tfirough tfie overflow toles.
Atout tolfivay down the tox is a diflliser plate to minimize resuspension of trapped
sediment.
Intet traps such as these are generally designed to capture hydrocaitons, sedimrait, and
floating detois. Ttore is general^ a large bufld up of grass, loives, and yard debris m the
GISBs; vMah represent a source of nutrients, which do not enter tfie watertodies. Royal
and England, 1999, determined that leaves and grass leach most of ttoir nuttients mto
tfie water wifliin 24-72 tours after being submerged in water. GISBs are designed to
keep captined debris m a dry state, off tiie tottom of flie inl^ Alius prtfvenUng ptoqihates
and nitrates from teaching into tto stormdrain system, where much more expensive
BMPs wouM to required to remove tto dissolved nutrients.
Methodology;
A test was designed to sunulate a rain&U event and measure tto alnUty of a GISB to
remove sediment and grass teaves fixim a typtoal grated inlet at 600 Soutfi Brevard Ave.,
Cocoa Beach, Ftorida. Joanto Regan of tto Cocoa Beach Stormwater UtiUty provkted
this tocation for flie test, as weU as a water tiuck to flush tto curbs. Universal
Engineoing Sciences performed tto testing, measurements, and sediment sanqiling,
Creech Engineeiing, Inc. observed tto testmg.
Tto City has instaUed a number of these devices and Joanto indtoated this tocation was
typical of a noimal instaUation. Tto grate, curb, and gpttex around and upstream of tto
inlet were brushed and washed clean. A new, clean GISB was placed inskte tto inlet. A
water truck wifli a pump discharged reuse water into tto gutter iqtstream of tto inlet at a
rate of 500 gpm (1.1 cfe). Dry, green St. Augustine grass clqipings fiom a yard that had
been recentfy fertiUzed were stowfy fed into tto gutter and fhished mto tto intet. It was
observed that tto cast iron grate trapped a agni&ant aniount of grass around tfie edges of
tto grate. Tto grate was lemDved for aU tests to enahte aU of tte grass and sediment to
enterttotox. After aU of a measured sampfe of grass had beat wastod into tte intet, tte
grass was removed fiom tte inlet, dried, and weighed. Saniptes of grass tofore and after
tto test were sent to PC&B Laboratories in Oviedo, Ftorida. Latoratory analysis was
performed to determine tte Total Ftoi^rus and TKN cont^ of tte grass.
Next, a sediment sample was wastod through tte GISB using tfie same metiiodotogy.
Universal Engineering ran a sieve size analysis, using ASTM D 422 procedures, tofore
and after tfie test. Tto sedhnent was classified as a pooiiy graded gravely sand. Tto
sediment was removed fiom tto GISB, dried, and weighed.
Results:
During totil oftfie tests, aU water leaving tfie GISB passed tfirough tfie filter screens.
Tto water levels m tto tox only rose a few mches, witfi no water passing through tto
overflow totes or coarse screens, even ttough tto tottom screens were completely
covered witfi grass or sediment There was a smaU amount of grass and sediment tfiat
passed totween tfie tox and tto concrete waUs of tto mtet because of tto uneven edges of
the inlet. This situation is Mr\y common in most inlets due to toose toterances in
construction techmques.
In the grass test, 6.58 fos. of grass were washed into tto inlet and 5.22 Ibs. were
captfxred, resulting m 1.36 fos. of grass passing through tto GISB. This represents a
removal efScieiwy of 79.3%, Tto pretest grass sanqile had a Total Ptosphorus content of
950 n^g and a TKN content of 510 mg/kg. The grass san^te removed fixim tto GISB
tod a Total Ptosptonis content of2,270 mg/kg and TKN content of905 mg/kg.
The sediment test was a Uttte more cotapktx. Tto imtial results stowed that of tto 57.87
fos. of sedimoit introduced to tto GISB, 42.41 fes. were cultured, grving a total ma^
removaiefBciaicy of 73.3%. Uiuversal Engmeering iiidk»tes tfiat tte Pretest sainpte had
10.7 % gravel 88.0% sand, and 1.4% ctey. Tte Post test sampte had 25.9% gravel,
14.7% sand, and 1.7% clay. Gravel is conskiered to to particles No.4 and larger. SUt
and clay is defined as parttoles passing tto No. 200 sieve.
Tabte 1
Sediment Sieve Analysis
Sieve Size 3/8" No.4 No.10 No.40 No. 60 No. 100 No.200
PreTest
% Passing
94,3 89.3 81.8 64.8 50.3 25.5 1.4
Post Test
% Passing
88.8 74.1 62.6 44.2 31.8 14.7 1.7
Difference 5.5 15.2 19.2 20,6 18,5 10,8 -0.3
Conclusions:
At tto flow rate tested, tte GISB removed 79.3% of tte grass cl^iinngs washed into iL
Tto ability of tto GISB to remove grass durii^ hurge flows v^ien water passes flnough
tto bypass totes was not tested. In Ftorida, 90% of tto storms are tow i^nfidl events of
1" or less, resuhing m low flows shnOar to tto test conditions. This makes tto GISB a
very effective BMP for Low flow events. It is unknovm tow effectively tto GISB works
in large storm events.
By keeping grass and otitor Happed organto debris m a diy state, tiie nutrients m tto
debris do not leach out and become dissolved nitrates and jixospiietes. Ito GISB is a
veiy efifective BMP for preventing nutriraits fixim organto debris fixim entering
waterbodies. Tto s^nificant hvaiease m nutrient concentration afier tto test is probably
attritoted to Ito use of wastewater reuse water during tto test Tto grass matted several
inches thtok in tto tottom of tto tox. This thtok layei coukI tove acted as a filter to
remove nutrients from tto water source.
At tiie flow rate of 1.1 cfe, flie GISB had a sediment removal efBciency of 73.3%. As
wouki to eiqiected, most of tto trapped sediment was gravel and sand, witfi Uttte fine
material coUected. Tto GISB has sedimrait removal ciq»lHUties rivalh^ ttose found m
many stiructural BMPs, at a fibtK^tton of tto cost, and wittout disruptive constructton.
UNIVERSAL
ENGINEERiNG SCIENCES
CamxJbm to GecMdviol En^naenng • Em«^^
Coramxto Ii4ateriab TesSng • nveshoU hispecta
820 Brevard Avenue • Rockledge, Florida 32955
(321) 638-0808 Fax (321) 638-0978
November 2,2001
Mr. Gordon England, P.E.
Creech Engineers, Inc.
4450 West Eau Gallie Boulevard
Melboume, Florida 32934
Reference: Grate Inlet Skimmer Box Evaluation
Northwest Comer of South Brevard Avenue and South 8"' Street
Cocoa Beach, Brevard County. Rorida
Universal Project No. 33186-002-01
Universal Report No. 51479
Dear Mr. England:
Universal Engineering Sciences, Inc. (Universal) has completed an evaluation of a Grate Intot
Skimmer Box (GISB) in accordance with Universal Proposal No. P01-0781. The evaluation was
conducted to document the pollutant removal effectiveness at the above-referenced site, A
Location Map. Site Map and Site Photographs are presented as Attachments 1, 2 and 3,
respectively.
Sediment Testing
Universal supplied the sediment sample for the GISB evaluation. The sediment sample
consisted of fine sands, coarse grain sands with crushed shells, and gravel, A gradation
analysis of the sediment sample (S-1) was performed, prior to GISB performance testing. The
percentages of soil grains, by weight, retained on each stove were measured and a grain size
distribution curve generated, to detenmine the textural nature of the sample and provkle a
confrol (baseline) prior to fieidworic
A sediment sampto of known weight (57.87 lbs.) was placed on the pavement upstream of the
GISB and washed into the GISB with a portable water source simulating a stonn event The
captured sediment was then removed fifom the GISB, dried and weighed. The captured
sediment weighed 42,41 Ibs, resulting in a toss of 15,46 Ito. from foe GISB testing, A gradation
analysis of the captured sediment sample (S-2) was performed.
Universal comptoted particle size analyses on the two representative sediment samples (S-1
and S-2), The samples were tested atxording to the procedures for mechanical sieving of
ASTM D 422 (Standard Method fbr Partide Size Analysis of Soils), in part, ASTM D 422
requires passing each spedmen over a standard set of nested stoves (V* inch. No. 4, No. 10,
No. 40, No. 60, No. 100, No. 200). The percentage of the soil grains retained on each stove size
are detennined to provtoe foe grain size distributton of the sample. The distribution ctetennines
the textural nature of the soil sample and aids in evaluating its engineering characteristics.
Mr. Gordon England
November 2, 2001
Page 2
ProjectNo. 33186-002-01
Report No. 51479
S-1 consisted of 10.7 percent gravel (grain size larger than 4.75 mm), 88.0 percent sand (grain
size between 0,075 mm and 4,75 mm), and 1,4 percent fines (grain size toss than 0,075 mm).
S-2 consisted of 25,9 percent gravel. 72.4 percent sand, and 1,7 percent fines. The grain size
disfribution curves are presented as Attachment 4. According to ttie Unified Soil aassification
System (USCS), S-1 and S-2 were dassified as pooriy-graded gravely sand [SP]. Based on foe
gradation analysis, foe major portion of foe tost sediment was foe fine sand component
Grass Clippings Test
The grass dippings were suppltod by Suntree Technologies, A grab sampto of grass (G-1) was
colleded and submitted for latoratory analysis to detemitoe ttie TKN (EPA Mettiod 351,2) and
Total Phosphorus (EPA Mettiod 365,3) content A grass sampte of known vweight (6.58 Ite.) was
ptoced on ttie pavement upstream of ttie GISB. The grass dippings were washed Into foe GISB
in foe same manner as foe sediment sample. The captured grass dippings were then removed
firom foe GISB, dried and weighed. The captured grass dippings weighed 5,22 Ito. resulting in a
toss of 1.36 lbs, A second grab sampte (G-2) was colleded finom ttie captured grass dippings
and submitted for tetoratory analysto to detennine foe removal efffciency for TKN and Totel
Phosphorus.
The samples were shipped to PC&B Latoratories, Inc. in Oviedo. Rorida. Latoratory analysis
documented 950 milligrams per Wtogram (mg/Kg) of Totel Phosphoms and 510 mg/l^ of TKN
for G-1. Latoratory analysto documented 2,270 mg/Kg of Totel Phosphoms and 905 mg/Kg of
TKN for G-2, LatoratcMy Analyfical Resulte and Ctoto-of-Custody Documentetion are presented
as Attechment 5.
Universal appreciates foe opportunity to provide environmentel services as part of your projed
team. Should you have any questions, please do not hesitate to contad foe undersigned at (321)
638-0808.
Respectfully submitted,
Unh^ersal Engineering Sciences, Inc.
James E. Adams
Steff Sdentist II
(2) Addressee
Attachments
Robert Aten Speed
Regional Manager
Rockledge Branch (Mce
Attachment 1:
Attachment 2:
Attechment 3:
Attachment 4:
Attachment 5:
Site Location Map
Site Map
Site Photographs
Soil Gradation Curves
Laboratory Analytical Resulte and Chaln-of-Custody Documentetion
\\uesrockVdata\reports\envrpt5\env2001\51479 gisb evaluafion report6oc
ATTACHMENT 1
SITE LOCATION MAP
UNIVERSAL
ENGMCEKMe SCEhCES
Grate Inl^ Skimmer Box Evaluation
Soutti Brevard Boutevard
Cocoa Beach, Brevard County. Rorida
SITE LOCATION MAP
J. AOAMS KMSIatatr;"
J-ACAMS
31479
TRIE—
1CW0W1
AnACHMENT 1
ATTACHMENT 2
SITE MAP
v. r
RESIDENTIAL
CONDOMINIUMS
CONDOMINIUM DRIVEWAY
(LANDSCAPED ^
MEDIUM J
RESIDENTIAL
CONDOMINIUMS
I
o
to
Ul Q
Ul 3
Z
I
Q
CD
X
V-
o
RESIDENTIAL
CONCRETE
DRAINAGE SWALE
SOUTH 8™ STREET
RESIDENTIAL
UNIVERSAL
ENQMEBVNGSCCNCES
Grate Inlet Skimmer Box Evaluatton
Soufo Brevaxl Bmilevard
Cocoa Beach, Brevard County, Florida
SITEMAP
3RMVNBY:
J. ADAMS
MTE
J. ADAMS 10OW01
rtTTftCHMfm-7
ATTACHMENT 3
SITE PHOTOGRAPHS
Grate Intet at 600 South Brevard Avenue, Cocoa
Beach
Grate Inlet Skimmer Box Features
Rorida Type Clniet
Storm Boom .
Zip Tie
SIdmmer Tray-
Deflection ShtokJ
Flange te reinforced
wifo knitted 1808 ±45°
biaxial fiberglass
CrVilLIZATiOM SNGIINieERED
PoUutant Ranoval Testing for a
Suntree Technotogies Grate Intet
Skimmer Box
SITE PHOTOGRAPHS
Sedhnent Entering GISB
Sediment Trapped in GISB
CIV eNGii^eeReD
PoUutant Rmnoval Testing for a
Suntree Technotogies Grate Intet
Skimmer Box
SITE PHOTOGRAPHS
GISB Inserted mto Inlet
Grass Testing
Ci^8il2AT80i ••\..-' BNGWEERBD
PoUutant Removal Testing for a
Suntree Techtotogtes Grate Inlet
Skimmer Box
SITE PHOTOGRAPHS
Grass Clqspmgs Entermg GISB
Sediment Testmg
PoUutant Rmioval Testing for a
Suidree Technotogies Grate Intet
SkimmarBox
SITE PHOTOGRAPHS
Photo No. 1: (Pre-Test) InsteHatton of new GISB
Ptoto No. 2: Start of tfie grass cHppingslest
Grate Inlet Skimmer Box Evaluatton
NWC of Soufo Brevard Avenue and Soufo 8'" Street
Cocoa Beach, Brevard Counfy, Florida
SITE PHOTOGRAPHS
NM
N<A
|»C6cbbV:
5M7B_ mm
tWSCMM
PAGE1
Photo No. 3: Storm simulation Ibr tto grass cKp test
test GISB removed fbr
Grate Intot Skimmer Box Evahiatton
NWC of Soufo Brevard Avenue and Soufo 8*^ Street
Cocoa Beach. Brevard County, Ftorida
SITE PHOTOGRAPHS
N/A aaocwK
N/A
1
msEwr '
PAOE 2
Photo No. 5: Stert of sediment test
Photo No. 6: Sediment test in progress.
v.
Km
Grate Inlet hammer Box Evaluation
NWC (rf Soufo Brevaid Avenue and Soufo 8*" Street
Cocoa Beach, Brevard County, Rorida
N/A
N/A
SITE PHOTOGRAPHS
icnom WUJkUIIWt
614^9 PAOES
m Skimmer Box Evaluation
NWC of Soufo Brevard Avenue and Soufo 8'" Street
Cocoa Beach, Brevard County, Florida m mamr.—•
NM
SITE PHOT
BiffE ~ 1 iwawoi
IHJUtUINU •
OGRAPHS
5i55BiF~ -—i m cponm •
S1479
10/30/01
ATTACHMENT 4
SOIL GRADATION CURVES
100
95
U.S. SIEVE OPENING IN INCHES
B * 3 2 ,5 1 ^ IO ^ J ^ 6 , 10 „» JO 30 ^ 80 TO WO ,^
U.S. SIEVE NUMBERS
14* n
HYDROMETER
90
85
80
P 75 E
N65
T
60
F
I 55
N
E SO
R
45
B
Y 40
|W35
^30
^ 25
20
15
10
5
0
5[
TTTTl
100 10 1
GRAIN SIZE IN MILLIMEIERS 0.1 0.01 0.001
COBBLES SAHP. nwoun I "IBS" SILTORCt>KY
Specimen Identification Classificalion MC% Pt PI Cc Cu
e 81 0.79 3.7
SEDIMENT1
specimen Identification D100 060 030 DIG %Gravel % Sand %Sit t 1 y >Clay
e Si 12.50 0.36 0.164 0.0961 10.7 88.0 1.4
3/4" 3«" NO.4 NO.10 NO.40 NO. 60 NO. 100 NO.200
94.3 89.3 81.8 64J 50.3 25,5 1.4
CHent CREECH ENGINEEraNG
4450 W. EAU GAtUE BOUtEVARD
MELBOURNE FLORIDA 32934
Project: GRATE INtET SKIMMER
BOXEVAtUATION
BREVARD COUNTS. FtORIDA
CItontNo:
Report No:
Oate:
33186-002-01
51479
10/9/01
SOIL GRADATION CURVES
Universal Enghieering Sciences. Inc.
U.S. SIEVE OPENING IN INCHES
6 T 6 * S *1.5'sM'2a«'4»8«M*»»
T r
U.S. SEVE NUMBERS
n
HYDROMETER
» 70 140 200 100
95
90
85
80
p
E 75
R
c 70
E
N 65
T
60
F
1 55
N
E 50
R
45
B
Y40
W 35
E
35
1 30 G 30
H
T 25
20
15
10
5
0
TT
10 1
GRAIN SIZE m MiUJMETERS
0.1 0.01 0.001
COBBLES SAND
coarae I inadium I THe" SBLTORCLAY
Specimen Identification
SEDIMENT 2
Classificalion MC% LL PL PI Cc
0.30
Cu
13.7
Specimen Idenlification D100 D60 030 DIO %Gravel %Sand %Sitt %Clay
32 12J0 1.61 0.237 0.1169 25.9 72.4 1.7
3/4" 3/8" NO.4 NO.10 NO.40 NO. 60 NO. 100 NO. 200 1
8801 74.1 62.6 44.2 31.8 14.7 1.7 1
CItent CREECH ENGiNEERING
4450 W. EAU GALUE BOULEVARD
MELBOURNE FLORIDA 32934
Client No:
Report No:
Date:
33186-002-01 1
51479 1
10/9f01 1
Project GRATE INLET SKIMMER
BOXEVAtUATION
BREVARD COUNTY, FLORIDA
SOIL GRADATION CURVES
Universal Enoineerbia Sciences. Inc.
ATTACHMENT 5
LABORATORY ANALYTICAL RESULTS AND
CHAIN-OF-CUSTODY DOCUMENTATION
A PC&B Environmental Laboratories, Inc.
210 Park Road, Oviedo, Florida 32765
Phone: 407-359-7194 Fax: 407-359-7197
Client: Universal Engineering Sdences
820 Brevard Avenue
Rockledge, FL 32955-
Laboratory Reference Number: 201090199
Project Name: Inlet Skimmer Box Evaluation
Project Number:
Laboratory ID Matrix Client ID
201090199-1 Soiid GT
Contact: James Adams
Ptione: (321) 638-0808
Chain of Custody: 24025
Status Date/rime Sampled
RUN 09/26)2001 14:20
Parameter
EPA 6010
EPA 9200/3512
Descftotion
Phosphorus by ICAP
Total Nitrogen
PC&B Environmental Laboratories, Inc.
210 Park Road
Oviedo, FL 32765-8801
407-359-7194 - (FAX) 407-359-7197
Case Narrative
James Adams
Universal Engineering Sciences
820 Br»raird Avenue
Rockledge, FL 32955-
CASE NARRATIVE fbr Woric Order 201090199
Project Number:
Project Name: Inlet Skimmer Box Evaluafion
This Case Narrative Is a summan/ of events and/or problems encountered with this Work Order.
Analysis for TKN was performed by Environmental Science Corporation (E87487)
Deflnlion of Flags
9^ - NosunogoteresuftcfaelodfciaonarmalriKWBffBtwM^ ~ ~" "
J ' E8llmHMVWu»,wiiMnotwctnla.
L « Oftw*hiBh.AclwlvaluBi8grartarthmvaiueglvm.
Q > SamiJieand^ beyond the acoeptodhokftn time.
T - VWuereporlad is lese than tfw ieboralaiy method (ta^^
V » Analyletm boat deiecM in the melhod fatamk and sample
PC&B Efflrinximental Laboratories, Inc.
210 Park Road
Oviedo, FL 32765-8801
PHONE: 407-359.7194
Report Of Analysis CUENT NAME: Universal Engineering Sciences
PROJECT NAIUE: InM Skimmer Box Evaluatton
PROJECTNUMBER:
DATE RECEIVED: 09Q6Q0Q1 Reference Number
SamplalD
Date/Time Sanqpied
Samoie Matrix fas Recelvad^
EPA 6010 Phosphoms, Total
EPA 9200/351.2 Total Nitrogen
201090199.1
G-1
09Q6G001
14:20
Solid
950 mg/kg
mg/kg 510
•Undetected. ^^'"«P^°««^'"fl'hey fetheRLfbrtt^^^^^ reported on . v.^ WIOM K.O,.
FDEPComp(Mt^^#9601340 - l^bbHeertification4fe83239
Reviewed by: jjUPTv
Quality Control Report for Spilce Analysis
INORGANICS
Lower Upper
*P*» Sampto Spike Percent Control Control
^^^"^ iwsffi^' ^^'^^^^^^^ '^^^
0 Park fWld, Oviedo, FL 32765
7-359-7194 (FAX) 407-359-7197 IChain df Custodvi Work Order:_2ei(t£/^
Paoe of
0 Park PUB, Qvi
7-359.7194 (i ^JT" IChain o^ustody Work Order: ^^li
4PUDBY:
«4Ma«
,PC&U Environmental Laboratories Ina
210 Park Road
Oviedo, FL 32765^1
Lab Referenoe Number
' CItent Sample ID
Date/Time Sampted
Samote Matrix faa
EPA 6010 Phosphoms, Total
EPA 9200/3512 Total Nitrogen
Repoit of Analysis
mg/kg
mg/kg
201100168-1
10/10/2001 0:00:
2270
905
PROJECT NUUfflER:
10/iag001
= Undetected. The valua nmnniwiin l^^** Y 's thf RL for the analyte Results rec
FDEPComD6APP#9o6l34G - I^65H ( >fted on a Wet Waiffhi hn«i«
trtltlcatnn li* E83239
Reviewed by:
PC&B Environmental Uboratories, Inc.
210 Park Road. Oviedo, Rorida 32765
Phone:407-359-7194 Fax:407-359-7197
Client: Universal En^eering Sciences
820 Brevard Avenue
Rockledge, FL 32955-
Laboratory Reference Number: 201100168
Prpject Name:
Project Number:
LaboratprylD Matrix
201100168-1 Solkl
Client ID
Contact: Bob Speed
Phone: (^1) 638-0808
Chain ofCustody: 20344
Status Date/Thne Sampled G-2 RUN 10/10/2001
Numbw
1
1
Parameter
EPA 6010
Descrtption
EPA920(V351Ji
Phosphoms by ICAP
Total Nitrogen
OCT 29 2801
Quality Control Report for Spike Analysis
INORGANICS
Lower Upper
Spto Sampfe Spike Percent Control Control
'''"•P'^.Totai 20.0 mg»B 178.0 lOOX) 105 70 120
SITE EVALUATION OF SUNTREE TECHNOLOGIES, INC.
GRATE INLET SKIMMER BOXES
FOR DEBRIS, SEDIMENT, AND OIL & GREASE
REMOVAL
Reedy Creek Improvement District
PkuuDg ft Engineeciiig Department
Eddie Snell, Compliance Specialist
Stoimwater is aow leoogmad as tie leadiqg soone of pdhtioa to oor lemaiiiiqg nabml
water Ixxfies in the uiiiled Stales. Devdopment and utmizitfifln have lemoved most of
die natund filtiitfion and sediment mppii^ sylstems provided by die environment Cunoit
devek^ent must address dus need dirou^ fte in^ementation of stonnwater
trealmenis ^sterns in die project des^ Moat of diese ^slems perfonn leasonai^ well,
if properiy destgned, ooosbacted, and nudnbnied.
Retrofit of ddor urban areas laddng diese modem stonnwater systems is a continually
eiqimtve cfaaOeoge. The Downtown DisnQr conqdex, fcmc^ die Lake Buena Vista
Shoppn^ Village, has several diainage basins widi '1970*s slum wate systems. These
older systems dsdiarge dnecC^ into die a^gaoent diainage cand widi no poQiitant
treatmcaiL Over dme die aocumuhtion of sediments, nutrieols, intensive devdopmoit,
and recrea^nal/oitaiaiDment pressures aie ccmtribo^ to water quality d^radaticm.
Whenever new devdofmxnt or redevdopment occura, die stoimwater system is brw^
to cmrent code^pennit lequirements. In tte interim, severd areas aoe in need Sx n^id,
effective, and ennxmiicd inqxovement in die quality of its stcmwater disduuge.
Simtaee Tedmdogies hiooipoialed, kicated in Cape Canaveral, FL, mamiftdanBs
stoimwatff grate idet ddmmw boxes. Th^ oe nude of a tai^ qrality fiboig^ fiame,
widi stainless steel filtor socens badced by heavy-duty dmninum giadng. Each unit is
custom made to accommodate variots idet sizes. A Itydrocaibon disorptioa boom is
aUached to die top of die ddmmer box fbr petrdnim, dl, and grease removal
These devices fit below die grate md catch sediment, ddxis, and petroleums, oils &
greases. Clean-out, maintenance, and peiformanoe reporting is provid Suntree on a
scheduled basis.
Picture of Grate bil^ £3dmmer BQK
The Reedy Creek Improvement District (RCID) sdected six (6) test sites in die Lake
Buraa Vista area to evduate die pofbnnance of diese units. One unit was placed in a
cuib inlet dong Hotd Plaza Boulevanl to trap landscape leaf fitter, sediment, and oil &
grease fiom a higji use roadway. Three (3) units were placed in the backstage service area
of die Rain Forest Cafe. Two (2) units were placed in the backstage service area of die
McDcxidd's restaunait and L^os merdiandise diop.
Afta- sevml field meetings, during wiiich Sunbee tock extensive measurements, photos,
and odier documentation of each sbxmw^ drain, die Grate Inlet Stdmma* Boxes were
manu&ctured and defivered for instdlatkn. All units woe installed widiout mishq)
iqqHX»dmately two weeks belne die 1999 Christinas holiday season. Ihe taiget time
period for particle catchment w^ one mondL Mr. Hairy and Tom Hai^l, Suntree
Technologies, visited each site severd times during die month to oisure tihat debris would
not fill die units too socm.
On Januaiy 25,2000, Suntree sCTviced die six units. At each site, da mataial c^tured in
the skimmer boxes was removed, measured, weired, visually idoitifi^ photogrq)hed,
and reccxded Some units woe sfi^^ ^ modified fiir qjtimmn perfomiaiKe. All
units perfixmed as eiqpected remote ca awerage, 20 poimds of ddirls fiem eadi of
the six sites. The compositioo of debris varied considerably.
The Hotel Plaza (roadway) site was 90% leaf litter and 10% sedimoit The Rain Ftxest
Cafe sites ran in q)positi(»i as you got close to die lake. First inlet was about 50% leaf
litter and dgaiette butts and 50% sediment The middle inlet was 60 %sediment and 30
% leaf litter (10% miscdhmeous). The inlet dosest to die hike was 95% sediment and 5%
leaf litter. The two sites at dus McDcHidds/L^ area wore similar to e«;h odier. Tlie
site closest to die Idre was 95% sedimoit and 5% leaf litiar. The site closest to die
oitrance gde vm 98% litter sediment aod 2% leaf Ihter.
I
This compositkin is indkative of die human activities and drainage flow patterns of tiiat
site. Backsti^ areas in die Wah jytsoey Worid Resort receive an ailificid rain event
each ni^t duiing deaning operations. This washes a continual flow over die imperviotK
site, washing dl matoials into die stormwater system.
Municipdities in ftevard, Volusia and Dade counties have successfiilly used inlet
skimmos in Florida. RCID pmtnered widi Walt Disney Imagineoing (WDI) Research
and DevelojHnoat to co(Hdinate scnne basic chemicd sanqilmg fisr pollutant removd
efficiency ddomination. Nfr. Crdg Dmdiuiy, WDI, provided technicd siqiport and
guidance finr dus. An ingmiousiy simile demce was fiibricated by Suntree to dbw
sami^g of die First Flush of water going into die units aiui ultimately coming out of die
skimmo- boxes.
Collected samples were processed aid analyzed by die RCID IMjoomottd S»vices
Laboratoiy. Analysis parameter were:
Ammonia, Chemicd Oxygen Demand, Feed Colifonn (MPN), Nitrite and Nitrate, Totd
Kjekiahl Nitrogen, Oil and Grease, Totd Phosphate, Suspended Sohds, and Metals.
Ana^is readts are piesented in die foUowmg table:
Pollutant
ANALYSIS LOCATiON LAB NO. VALUE UNITS 8AM-DATB Change
Ammof^, Salloylato RF-IN 1646 0.36 mg/1 oe^^eb^ 0.14
Ammonia, SdioyMt RF^UT 1646 0.23 mg/l 09M40
Ammonia. Saik^lste RF^UT-I 1646 0.25 mg/1 094:eb^
Chemicd OxyQ/an Demand RF-IN 1646 2670 mg/1 09-FdKOO 1036
Chemicd Oxygen Demand RF-OUT 1646 1780 mg/1 09-Fd>O0
Chemlod Oxygen Demand RF-OUT-I 1646 1490 mg/1
CoMorm, Feoal MPN RF-IN 1646 1600 «IOO ml 004:d>00 •93400
CoWbrm, Feed MPN RF-OUT 1646 160,000 HOG ml 094:SbO0
CoMonn, Fecal MPN RF-0UT4 1646 30,000 HOG ml 00-FdKOO
NKnrte and NHtrfte RF-IN 1646 0.06 mg/1 OQ-FebOO 0.036
Nitrate and NKrito RF-OUT 1646 0.04 mg/1 09#eb^
NItnrte and Nitrite RF-OUT-I 1646 om mg/1 09-Feb^
Nitrogen, Totd iqddahl RF-IN 1646 24.3 mg/i O94:d>00 13.65
Nitrogen, Totd iqddahi RF-OUT 1646 10.4 mg/1 09^ib^
Nitrogen, Totd iqddahl RF-OUT-I 1646 11.1 mgA 094^ebO0
Oil and Orease RF-IN 1646 G26 mgA 09^eb-00 283
%
Chanae
37%
Pdlutant removal effickneies averaged about 50% fex all patameters tested. The mintewl ranoval was
37% for Afflinooia and the maximum removal was 74% fix Suspended Sdids.
Colifixm bacteria were not effectively removed by the ddmmer boxes, dthough, thq^ are not designed to
pravide wato* dislnftctioa Oil and Grease are a fixxl souce for bacleria and reduction of ftis poUutant
should provide sraie e£foct on badenal mmbers.
Pollutant Removal Efficiency
80%
70%
60%
c 50%
0
€ 40%
tr
30%
I Ammonia,
Salicylate
• Chemical Oxygen
Demand
•Nkrata and Nlrle
• Nitrogen, Total
Kjeldahl
• Oil and Grease
• Phosphate, Tdal
• Solids, Suspender
20%
10%
0%
% Change
Parameter