HomeMy WebLinkAboutCT 00-06; Bressi Ranch; Water Quality Plan; 2000-04-01RECEIVED
OCT 3 0 2003
CITY OF CARLSBAD
PLANNING DEPT.
INDUSTRIAL CONCEPT WATER
QUALITY PLAN
FOR
BRESSI RANCH, TM CT 00-06
CITY OF CARLSBAD, CA
APRIL 2002
Prep£ired For:
LENNAR COMMUNITIES
c/o LENNAR BRESSI VENTURE, LLC
5780 Fleet Street, Suite 320
Carlsbad, CA 92008
Prepared By:
PROJECTDESIGN CONSULTANTS
701 B Street, Suite 800
San Diego, CA 92101
Job No. 1325.00
TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION 1
2.0 NPDES INDUSTRIAL AND MUNICIPAL PERMIT PROCESS 4
3.0 INDUSTRIAL POLLUTANT LOADS 5
4.0 BMP POLLUTANT REMOVAL EFFICIENCY 7
5.0 PROJECT BMP DESIGN CRITERIA 8
6.0 PROJECT BMP DESIGN RESULTS 9
7.0 INDUSTRIAL BMP PLAN IMPLEMENTATION 10
7.1 Project BMP Source Control Options 11
7.2 Project BMP Treatment Control Options 12
8.0 CONCLUSION 14
FIGURES
1 Vicinity Map 3
TABLES
1 Industrial Land Use Pollutants and Concentrations 6
2 PA Industrial Pollutant Loads A-l
3 BMP Treatment Controls 7
4 BMP Pollutant Removal Efficiency 8
5 BMP Design Criteria 9
6 Grass Lined Biofilter BMP Discharge and Treatment Area A-3
7 Individual Planning Area Wet Pond/Retention Basin Treatment Volumes A-4
and Basin Geometries
8 Combined Planning Area Wet Pond/Retention Basin Treatment Volumes A-5
and Basin Geometries
REPORT/13251CWQP.DOC j|
APPENDICES
1 Planning Area Pollutant Loads and Support Documentation
2 Nationwide BMP Treatment Controls
3 Table 6: Grass Lined Biofilter BMP Discharge and Treatment Area
4 Table 7: Individual Planning Area Wet Pond/Retention Basin Treatment
Volumes and Basin Geometries
5 Table 8: Combined Planning Area Wet Pond/Retention Basin Treatment
Volumes and Basin Geometries
6 Industrial Storm Water Source Control BMPs
7 Industrial/Municipal Storm Water Treatment Controls
8 Industrial/TVIunicipal Proprietary BMPs
EXHIBITS
A Site Layout Map
REPORT/13251CWQP.DOC -jj
1.0 INTRODUCTION
This report provides a "concept" water quality plan for the industrial land use component of the
Bressi Ranch environmental document. The property, which totals approximately 585.1 acres, is
located southeast of the intersection of El Camino Real and Palomar Airport Road in the City of
Carlsbad, Califomia (see Figure 1: Vicinity Map on page 3)). The site consists of an irregular-
shaped piece of property, which is bound by: 1) Palomar Airport Road to the north; 2) El Camino
Real to the west; 3) undeveloped property to the south; and 4) the Rancho Carrillo development
to the east. The Tentative Map proposes to develop 623 dwelling units and 2,160,000 square feet
of industrial space. The industrial PAs are identified as PA-1, PA-2, PA-3a, PA-3b, and PA-4
and PA-5 on Exhibit A.
From a drainage perspective, existing land use conditions (open space) generate approximately
705- and 52-cubic feet per second (cfs), which drain to Batiquitos Lagoon and the Encinas Creek
watershed, respectively. Under developed land use conditions the entire Bressi Ranch
development drains to Batiquitos Lagoon. This includes 444 cfs from the industrial PAs and 621
cfs from the residential PAs. Note that detention basins, located along the southerly edge of the
Bressi Ranch boundary, will be used to attenuate storm runoff back to existing conditions. The
preceding storm water runoff information was acquired from the, "Preliminary Drainage Report
for Bressi Ranch Planning Area 1-14 and Open Space 1-6", March 2000, prepared by
ProjectDesign Consultants. Note that storm runoff under both existing and proposed site
conditions do not drain to Agua Hedionda Lagoon.
Conceming water quality, the industrial PAs will generate approximately 26.7 cfs of storm water
treatment mnoff and approximately 306,444 cubic feet of treatment volume, per the numeric
sizing criteria presented in San Diego Regional Water Quality Control Board (RWQCB) Order
Number 2001-01 (Order 2001-01). Section 2.0 provides a detailed discussion of the numeric
sizing criteria.
It is important to note that during final engineering other treatment control BMPs may be
included in the BMP plan options presented herein. In effect, this documents lays the
REPORT/I325ICWQP.DOC 1
groundwork for the development of future industrial water quality plans by each Planning Area
(PA) industria] user. In general, this report includes the following:
An overview of the industrial and municipal permit process;
Existing and proposed land use condition pollutant load analysis;
"Concept" Best Management Practices (BMP) volume- and flow-based) design
hydrology;
"Concept" geometric requirements for retention and grass-lined BMPs, per the design
hydrology;
Selection of additional source and treatment control industrial BMPs that may be
evaluated for use by the industrial users during final engineering;
"Concept" project BMP water quality plan options for this project; and
Manufactures information for proprietary industrial BMP devices.
REPORT/13251CWQP.DOC
Project site.
^MELROSE
DRIVE
POINSETTIA
LANE
Figure I. Viciaity Map
RHP/I325SPDR.DOC
2.0 NPDES INDUSTRIAL AND MUNICIPAL PERMIT PROCESS
The Califomia State Water Quality Control Board (SWQCB) Order Number 97-03-DWQ (Order
97-03), National Pollutant Discharge Elimination System (NPDES) General Permit Number
CASOOOOOl, will regulate storm water discharges from the proposed industrial Planning Areas
(PA) associated with the Bressi Ranch Development. Order 97-03 generally requires industrial
facility operators to:
Eliminate unauthorized non-storm water discharges;
Develop and implement a storm water pollution prevention plan (SWPPP); and
Perform monitoring of storm water discharges and authorized non-storm water
discharges.
In addition, industrial storm water discharges from the PAs that enter the public, or municipal
storm drain system, are also regulated by Order 2001-01 that specifies storm water discharge
requirements for discharges of urban mnoff from municipal storm drain systems. From a design
perspective. Order 2001-01 sets hydrologic criteria required for the evaluation and design of
industrial and municipal Best Management Practices (BMPs).
The BMP hydrologic design criteria, pursuant to regional Order 2001-01, are either volume- or
flow-based. Specifically, volume-based BMPs must be designed to treat the volume of runoff
produced from a 24-hour 85"^ percentile storm event. In general, this is equal to 0.6 inches of
mnoff for San Diego County. Examples of volume based BMPs are retention/wetland ponds and
extended duration detention basins.
Flow-based BMPs must be designed to treat a flow rate of 0.2 inches of rainfall per hour. In
general, regardless of the criteria used, storm flow must be removed and treated before re-
entering the storm drain system. Examples of flow based treatment control BMPs include grass-
lined swales and CDS units.
REPORT/1325ICWQP.DOC
In addition to treatment controls, source controls BMPs are a key component of the industrial
water quality SWPPP. Good house keeping practices are the key source control BMPs, which are
primarily used to prevent or mitigate the exposure of industrial materials, i.e. significant
pollutants, to rain. These BMPs may primarily include indoor storage, outdoor covered storage,
and containment structure.
3.0 INDUSTRIAL POLLUTANT LOADS
The "Guidance Manual for the Preparation of Part lof the NPDES Permit Application for the
Discharges from Municipal Separate Storm Sewer Systems, EPA 1991, outlines an analytical
methodology for the evaluation of seasonal and/or annual pollutant loads. This approach
accounts for land use, impervious area, and anticipated mean pollutant concentrations for a given
the land use. Note that the pollutant concentration is primarily based on Nationwide Urban
Runoff Program (NURP) data and Camp Dresser McKee Inc. (CDM) pilot studies. The
equations used in the analysis are as follows:
RL=[Cp+(CrCp)IMPL]*I (1)
Where: RL = total average annual surface mnoff from land use L (in/yr)
IMPL = fractional imperviousness of land use L from Table 2
I = long-term average annual precipitation (in/yr)
Cp = pervious area mnoff coefficient = 0.15
Ci = impervious area runoff coefficient = 0.90
And;
ML=[EMCL*RL*K*AL]*I (2)
Where: ML= loading factor for land use L (Ib/yr)
EMCL=event mean concentration of mnoff for the lands use (mg/L): varies by
land use and pollutant
RL=total average annual surface mnoff from land use L computed from equation
1 (in/yr)
REPORT/1325ICWQP.DOC C
K=0.226 (unit conversion)
AL=area of land use L (acres)
Conceming existing and developed conditions pollutant loading for this project, Table 1 below
lists anticipated pollutants and concentrations that could be generated from the existing drainage
areas (as defined by the boundary limits of PAs 1-5) and PAs 1-5. The types and concentrations
of pollutants, per the NURP and CDM data, are documented in the Municipal Califomia Storm
Water Best Management Practice Handbook (Municipal Manual). See Appendix 1, Table 2, for
pollutant load estimates for each land use condition. Also, Appendix 1 contains the support
documentation for the EPA pollutant load analysis methodology, and the existing open space and
industrial land use pollutant concentrations shown in Table 1 below.
Table 1: Existing and Industrial Land Use Poliutants and Concentrations
Description Open Space Industrial
Mg/L Mg/L
Oxygen Demand and Sediment: BOD 8.0 9.7
COD 51.0 61.0
TSS 216.0 91.0
TDS 100.0 100.0
Nutrients: TP 0.23 0.24
SP 0.06 0.10
TKN 1.36 1.28
N02/N03 0.73 0.63
Heavy Metals: Pb 0.00 0.13
Cu 0.00 0.04
Zn 0.00 0.33
Cd 0.00 0.002
0.00
Total: 377.4 mg/ 264.5 mg/L
*The pollutant loads are based on a commercial/office/industrial development with 70%
to 90% imperviousness.
REP0RT/1325ICWQP.D0C
Table 1 shows that the total pollutant load under existing land use conditions is higher than under
developed conditions. This is primarily due to the high TSS concentration (sediment) that is
generated under existing open space conditions. This value may be high due to the good quality
of the vegetative cover, which protects the watershed from erosion. Note; however, that the
remaining pollutants loads under developed conditions are higher than those identified under
existing conditions. This is typically of an open space watershed that is developed for residential
and/or industrial land use. The results of the pollutant load analysis show that the existing open
space and industrial land uses generate pollutant loads of 18,543 Ib/yr and 63,292 Ib/yr,
respectively. See Appendix 1, Table 2, for the analysis.
The following Sections address project specific BMPs and BMP plan implementation. However,
Table 3 below lists a variety of effective treatment control BMPs for each pollutant category
above. In addition, more detailed BMP technical backup information is included in Appendix 5.
Table 3: BMP Treatment Controls
Description Most Effective BMP Adequate BMP
Oxygen Demand and Sediment: Infiltration
Constmcted Wetlands
Wet ponds
Biofiiters
Extended Ponds
Media filtration
Oil/water sep.
Multiple systems
Nutrients Constructed Wetlands Infiltration
Wet ponds
Biofiiters
Extended ponds
Media filtration
Oil/water sep.
Multiple systems
Heavy Metals Infiltration
Constructed wetlands
Wet ponds
Biofiiters
Extended ponds
Media filtration
Oil/water sep.
Multiple systems
Oil and Grease Infiltration
Constructed Wetlands
Oil/water sep.
Wet ponds & Biofiiters
Extended ponds
Media filtration
Multiple systems
REPORT/l 3251CWQP.DOC
4.0 BMP POLLUTANT REMOVAL EFFICIENCY
In general, a number of engineering and climatic conditions ultimately affect the selection of MP
treatment controls used in a project water quality SWPPP plan. A critical path item in the BMP
selection process is the contaminant removal efficiency associated with treatment control BMPs.
Table 4 below identifies typical contaminant removal rates for a number of BMPs. In addition,
Appendix 2 contains a matrix that includes a detailed list of BMP treatment controls and
associated benefits and pollutant removal efficiencies. Listed at the end of this document are the
references used in the development of the data.
Table 4: BMP Pollutant Removal Efficiency
BMP Type Suspended
Solids
Nitrogen Phosphorous Pathogens Metals
Dry Detention
Basin
30-65 15-45 15-45 <30 15-45
Retention
Basins
50-80 30-65 30-65 <30 50-80
Constructed
Wetlands
50-80 <30 15-45 <30 50-80
Infiltration
Basins
50-80 50-80 50-80 65-100 50-80
Porous
Pavement
65-100 65-100 30-65 65-100 65-100
Grass swales 30-65 15-45 15-45 <30 15-45
Vegetated
Filter Strips
50-80 50-80 50-80 <30 30-65
5.0 PROJECT BMP DESIGN CRITERIA
Grass-lined bio-filters/strips and retention/wetland basins have been identified as potential BMP
candidates for this project. The design of these BMPs is primarily based on the numeric sizing
criteria defined in Section 2.0. In general, Table 5: below summarizes the criteria that should be
implemented in the design of these BMPs:
REPORT/13251CWQP.DOC
Table 5: BMP Design Criteria
BMP BMP Hydrology Treatment Area/Volume Design Constraints
Grass-lined
Biofilter/Strip
Flow-based: 0=CIA
1 = 2 in/hour over
C= runoff coefficient
A = PA acreage
1000 sqft. of biofilter/acre
of impervious area.
Use geometry and
longitudinal slope that
maintain sheet flow and low
conveyance velocities.
Retention
Basin/Wetland
Pond
Volume based: .6-
inches of mnoff
.6-inches of runoff over
the impervious portion of
the drainage area.
Potential soil and ground
water constraints must be
addressed before selecting
this BMP. Geotechical and
City must be consulted
regarding these issues.
Retention time should range
between 40 and 72 hours to
promote treatment efficiency
and control for vector control.
6.0 PROJECT BMP DESIGN RESULTS
Biofilter/Strips
The Rational Method was used to determine the biofilter flow-based design discharge for each
individual PA. The hydrologic analyses, which are located Appendix 3, Table 6, were used to
determine the required biofilter treatment area and length required to treat the storm water within
a 50-foot buffer zone (width) that is located along the northerly edge of the project. The biofilter
treatment area and length are also included in Table 6.
The results of the analysis show that a biofilter, if used as the sole BMP for the project PAs, will
require a significant amount of area to effectively treat storm water. PA design options to reduce
biofilter treatment area would be to: 1) increase pervious area throughout the industrial complex
with planters and gravel walkways etc.; and/or 2) incorporate mechanical treatment control
BMPs such as CDS units etc. into the water quality plan. Note that the BMP hydrology
calculations in Appendix 3, Table 6, included a 20 percent reduction in impervious area due to
anticipated landscaping.
REPORT/1325ICWQP.DOC
Currently, Order 2001-01 states that only a portion of the storm drain design flow, i.e. .2
inches/hr (first flush)), may be used in the design of flow-based BMPs. However, it may be
possible to treat the entire storm flow within the biofilter if sheet flow (minimal depth) and low
velocities are maintained, so as not to suspend the first flush pollutants. This type pf BMP design
would have to be approved by the City and RWQCB.
Retention Basins (Wetland Ponds)
Wetland Pond/retention basin volumes were determined for both individual and combined PAs
using the volume-based BMP design criteria. The results of this "concept" analysis also show
that the basins, if used as the sole BMP for the project, would require a significant amount of
area to effectively treat the storm water. PA design options to reduce basin volumes, i.e. surface
area, are similar to those identified above under the discussion on biofiiters above.
Appendix 4, Table 7, and Appendix 5, Table 8, show the "concepf treatment volumes that
would be required if each PA constructed its own basin, or if a single joint-use basin were
constmcted to treat storm water mnoff from more than one PA. In addition. Tables 3 and 4 also
include a matrix that shows the surface dimensions of the basin for a number of basin depths.
7.0 PROJECT INDUSTRIAL BMP PLAN IMPLEMENTATION
This section identifies several "concepts" BMP plan options for the Bressi Ranch industrial PAs
that should meet the applicable stormwater and water quality ordinance requirements for
industrial sites. This includes incorporating BMPs that minimize runoff contamination and storm
water runoff from the site. These plans were developed per the proposed and PA layout shown
on Exhibit A.
BMPs other than those identified herein, may be selected during final engineering. Note that the
City has yet to implement its policy for compliance with the Order 2001-01, or develop specific
BMP Standard Drawings. This may ultimately affect the selection of industrial BMP treatment
REPORT/1325ICWQP.DOC
I
10
controls for the project. Therefore, the following BMP plan is "conceptual" and subject to
change pending City review and implementation of future policy requirements.
Per City of Carlsbad comments on the previously sumbitted version of this report dated July
2001, it should be noted that:
Each Planning Area is responsible for on-site control of pollutants. Basins, landscaped
niters, or improved BMPs shall be located onsite of each planning area and should be
maintained by the respective owner.
The following assumptions were used in the development of the BMP Plan for this project:
Only onsite flows will be treated. All offsite flow treatment will be the responsibility of
the upstream owners.
Runoff coefficients, 'C values, of 0.95 were used in the runoff calculations for industrial
areas.
CDS units will be accepted for use in the City of Carlsbad.
The following sections address the use of industrial/municipal BMPs only. During
construction, BMPs such as desilting basins and other erosion control measures will be
employed, consistent with the Constmction NPDES permit Storm water program.
7.1 Project BMP Source Control Options
Source controls BMPs are operational practices that prevent pollution by reducing the pollutants
at the source by not allowing the pollutants to enter the storm water or non-storm water runoff.
Treatment control BMPs are typically structural methods for removing pollutants from the
runoff. While, source control BMPs are typically less expensive to install and maintain than
treatment control BMPs, they may not be sufficient to effectively reduce pollutants in the runoff.
Typically for large project sites such as Bressi Ranch source control BMPs are used in
conjunction with treatment control BMPs to provide effective BMP storm water treatment.
Source control BMPs considered for use in the industrial areas includes, but are not limited to:
Standard good-housekeeping principles;
REPORT/1325ICWQP,DOC j j
Standard good-housekeeping principles;
Storm drain system inlet stenciling;
Employee training;
Spill containment methods;
Properly designed covered materials and trash storage areas;
Properly designed vehicle and equipment loading, fueling, maintenance, and washing areas
to prevent mnoff contamination or non-storm runoff;
Minimize directly connected impervious areas where applicable; and
Erosion protection.
See Appendix 7 for additional treatment control BMPs, per the Industrial Califomia Storm Water
BMP Handbook.
7.2 Project BMP Treatment Control Options
The BMP Plan Options below address the use of treatment control methods using flow based and
volume based BMPs. The following BMPs address general non-point source site runoff issues
and do not address industry specific point source discharges, which are covered under separate
state and regional regulations.
Option 1: Grass Biofiiters and Strips
This option includes the use of onsite grass-lined swales (biofiiters) to provide runoff treatment.
Table 6 in Appendix 3 provides the treatment discharge and the minimum treatment surface area
for each individual PA. The treatment areas are based on an assumed impervious area of 80
percent for each PA and minimum design criteria of 1000 sq-ft. of vegetative treatment area per
acre of impervious acre (see Municipal Manual). Review of the project layout shows that a grass-
lined swale may be placed in the 50-foot buffer zone along Palomar Airport Road. This would
require either grading and/or a storm drain system that conveys the runoff to the buffer zone.
REPORT/1325ICWQP.DOC 12
Option 2: Wetland Pond/Retention Basins
Retention basins are a volume based BMP that may be employed to treat the site mnoff. Tables
7 and 8 in Appendices 4 and 5, respectively, provide treatment volumes for each individual PA
and various scenarios of combined PAs. In addition, the tables provide preliminary basin depths,
widths, and lengths.
The basin volumes presented in this report are intended as a preliminary design aid that can be
used to determine the location of the basin(s) during final engineering. Retention basins could be
provided for each individual planning area or combinations of areas. For example, a joint use
basin could be constmcted at the southeast comer of Palomar Airport Road and El Camino Real
to provide treatment for PAs 3 through 5.
The use of retention basins assumes that proper infiltration can be achieved within 40-to 72-
hours, which promotes storm water treatment efficiency and controls vectors such as mosquitoes
and rodents. Based on information from the geotechnical/soils engineer, the soil within the
industria] planning areas is predominately Tertiary Torrey Sandstone, which has a generally
medium infiltration capacity.
Note that further evaluation of Options 1 and 2 is required during final engineering due to
uncertainty associated with the final site plan and type of industry. The use of these BMP options
are also dependent on: 1) the ability to direct first-flush flows to the BMPs, 2) the space required
by the BMP, 3) soil infiltration rates, and 4) the co-mingling of treated versus untreated flows.
Option 3; CDS Units
An altemative to swales and retention basins, in-line flow based BMPs such as CDS Pollutant
Trap Treatment Units (Units) may be installed at strategic locations prior to discharging the
onsite runoff to the storm drain system (see Appendix 8 for more information on these devices).
REPORT/13251CWQP.DOC 13
The CDS Units may be located 1) within in each planning area or subarea prior to discharging to
the publicly maintained storm drain system, 2) at central locations designed to treat a
combination of industrial area flows, or 3) at central locations designed to treat a combination of
industrial, residential, and mixed-use area flows.
Note that Fossil Filter Inlet Inserts were provided as an option in the July 2001 version of this
report. Based on City comments, the Fossil Filter Inlet Inserts have been removed as a BMP
option. The City does not consider Inlet Inserts as a favored BMP for tentative map stage design
and planning.
Option 4; Combination of BMP Options 1 through 3
Due to the uncertainty associated with the industry user and final site layout for each PA,
flexibility is required in the selection of the BMPs. As a result, combination of the above BMP
options may be needed to provide the most efficient and cost-effective BMP water quality plan.
In addition, during final engineering other treatment control BMPs may compliment the options
presented herein. In effect, this documents lays the groundwork for the development of future
industrial SWPPPs, or water quality plans, by each PA industrial user.
Some of these options include the possibility of combining BMPs for several Planning Areas.
The combination of Planning Area BMPs will require futher study in light of the City's request
that each Planning Area be individually responsible for on-site pollutant control. In some
specifically approved cases, BMPs for different Planning Areas could possibly be combined.
8.0 CONCLUSION
This report provides a "concept" water quality plan for the industrial land use component of the
Bressi Ranch environmental document. This "concepf water quality report provides BIvlP
options, or schemes, for the Bressi Ranch industrial PAs that should satisfy the requirements
identified in the following documents: 1) Carlsbad Municipal Code Stormwater Management
REPORT/1325ICWQP.DOC 14
and Discharge Control Ordinance, 2) Standard Specifications for Public Works Construction,
and 3) State NPDES Orders 97-03-DWQ, and 2001-01.
In general, this report includes the following:
An overview of the industrial and municipal permit process;
Existing and proposed land use condition pollutant load analysis;
"Concept" Best Management Practices (BMP) volume- and flow-based) design
hydrology;
"Concepf geometric requirements for retention and grass-lined BMPs, per the design
hydrology;
Selection of additional source and treatment control industrial BMPs that may be
evaluated for use by the industrial users during final engineering;
"Concepf project BMP water quality plan options for this project; and
Manufactures information for proprietary industrial BMP devices.
It is important to note that during final engineering other treatment control BMPs may be
included in the BMP plan options presented herein. In effect, this documents lays the
groundwork for the development of future industrial water quality plans by each PA.
Each Planning Area is responsible for on-site control of pollutants. Basins, landscaped
filters, or improved BMPs shall be located onsite of each pianning area and should be
maintained by the respective owner.
REPORT/1325ICWQP.DOC 15
APPENDIX 1
PA POLLUTANT LOADS
AND
SUPPORT DOCUMENTATION
REPORT/1325ICWQP.DOC
TABLE 2
BRESSI RANCH
PLANNING AREA EXISTING CONDITION OPEN SPACE
AND
DEVELOPED CONDITION INDUSTRIAL POLLUTANT LOADS
AVERAGE ANNUAL SURFACE RUNOFF (R)
Cp Ci IMP 1
(in.)
R(l)
in/yr
0.15 0.9 0.8 10 7.5
LOADING FACTOR FOR INDUSTRIAL LAND USE IM,)
PA EMC Rl K Area Ml
(mg/l) (in/yr) (conv. factor) Ib/yr
1 264.5 7.5 0.2266 2.3 1034
2 264.5 7.5 0.2266 22 9889
3a 264.5 7.5 0.2266 25.5 11463
3b 264.5 7.5 0.2266 21 9440
4 264.5 7.5 0.2266 39 17531
5 264.5 7.5 0.2266 31 13935
Total 140.8 63292
AVERAGE ANNUAL SURFACE RUNOFF (R)
Cp Ci IMP 1
(in.)
R(l)
in/yr
0.15 0.9 0.005 10 1.54
LOADING FACTOR FOR EXISTING LAND USE (M,)
Drainage EMC Rl K Area Ml
Basin (mg/l) (in/yr) (conv. factor) (acres) Ib/yr
1 377.4 1.54 0.2266 140.8 18543
Step 4 - Select BMPs
The most cost-effective BMP scenario is selected using Worksheet 2 in Chapter 3. The first
step in setting up Worksheet 2 is to determine the average annual pollutant loading from th;
site prior to development (i.e, pasture with no BMPs), the annual pollutant load increase due to
the development, and the average annual pollutant loading under each of the three BMP
scenarios identified in Step 3. The purpose is to compare projected non-point source pollutant
loads before and after development in order to identify the load reductions that could be
achieved by placing different BMP options. The NURP data and/or other local studies could
be used for pollutant load estimates, runoff estimates, or removal efficiencies.
For this example, pollutant loads were simulated using the Camp Dresser & McKee Inc.
(CDM) Watershed Management Model (WMM). WMM is a spreadsheet-based tool for annual
and/or seasonal load evaluations based on the methodology outlined in the Guidance Manual
for the Preparation of Part 1 of the NPDES Pennit Application for Discharges from Municipal
Separate Storm Sewer Systems. EPA, 1991. EMCs and impervious values for WMM are
shown in Table 2. These are based upon NURP data and CDM experience. For WMM,
annual runoff volumes for the pervious/impervious areas in each land use category are
calculated by multiplying the average annual rainfall volume by a runoff coefBcient. A runoff
coefficient of 0.9 is typically used for impervious areas (i.e., 90 percent of the rainfall is
assumed to be converted to runoff from the impervious fraction of each land use). A pervious
area runoff coefficient of 0.15 is typically used. The total average annual surface mnoff from
a given land use L is calculated by weighting the impervious and pervious area runoff factors
for each land use category as follows:
RL = [ Cp + (C, - Cf) IMPL 1*1 Equation 1
Where: R,. = total average annual surface runoff from land use L (in/yr)
IMPL = fractional imperviousness of land use L from Table 2
I = long-term average annual precipitation (in/yr)
Cp = pervious area runoff coefficient = 0.15
CI = impervious area nmoff coefBcient = 0.90.
The WMM generates nonpoint source pollution loads (expressed as Ibs/yr) that vary by land
use and the percent imperviousness assodated with each land use. The pollution loading
factor ML is computed for land use L by the following equation:
A/t = EMCL • /fi * A- * At Equation 2
Where: ML = loading factor for land use L Gb/yr)
EMCL = event mean concentration of runoff from land use L (mg/L);
EMCi, varies by land use and by pollutant
Rt. = total average annual surface nmoff from land use L computed from
Equation 1 (in/yr)
K = 0.2266, a unit conversion constant
A[. = area of land use L (acres).
The loads are then summed for a given area or scenario to produce summary results without
BMPs. BMP efficiencies are then j^lied as fractional removal coefficients to reduce annual
loads.
Municipal Handbook B - 4 March, 1S>93
1
m g
a Event Mean Concentrations And Impervious Percentages
Assigned For The Watershed Management Model
Oxygen Demand & Sediment Nutiients Heavy Metals
Land Use IDercent
Impervious
BOD
mg/L
COD
mg/L
TSS
mgA.
TDS
mg/L
TP
mg/L
SP
mg/L
TKN
mg/L
N023
mg/L
Pb
mg/L
Cu
mg/L
Zn
mg/L
Cd
mg/L
Forest/Open 0.5% 8.0 51 216 100 0.23 0.06 1.36 0.73 0.00 0.00 0.00 0.00
Agriculture/Pasture 0.5% 8.0 51 216 100 0.23 0.06 1.36 0.73 O.OO 0.00 O.OO 0.00
Cropland 0.5% 8.0 51 216 100 0.23 0.06 1.36 0.73 0.00 0.00 0.00 0.00
Low Density Residential 10.0% 10.8 85 140 100 0.47 0.16 i.is 0.96 0.18 0.05 0.18 O.OOi Medium Density
Residential 30.0% 10.8 83 140 100 0.47 0.16 2.35 0.96 0.18 0.05 0.18 0.002
High Density Residential 50.0% 10.8 83 140 100 0.47 0.16 2.35 0.96 0.18 0.05 0.18 0.002
Commercial 90.0% 0.7 61 91 100 0.24 0.10 1.28 0.63 0.13 0.04 0.33 0.001
Office/Light Industrial 70.0% 0.7 61 91 100 0.24 0.10 1.28 0.63 0.13 0.04 0.33 O.OOi Heavy Industrial 80.0% 0.7 61 91 100 0.24 0.10 1.28 0.63 0.13 0.04 0.33 O.OOi
Water 100.0% 3.0 22 26 100 0.03 0.01 0.60 0.60 0.00 0.00 0.11 0.000
Wetiands 0.5% 8.0 51 216 100 0.23 0.06 1.36 0.73 0.00 0.00 0.00 0.00
Major Highway 0.V 103 141 100 0.44 0.17 1.78 0.83 0.05 0.37 0.0011
ea
Ul
Source: EPA, 1983 and CDM experience
APPENDIX 2
NATION WIDE BMP TREATMENT CONTROLS
Nationwide Examples of Treatment Control (Structurai) Best Management Practices (BMPs)
Trealment Control (Source) Limitations Benefits Removal Efficiency Capital Cost
(approximate)
O&M Cost
(approximate)
Inflltration - a family of treatment
systems in which the majority of the
runoff from small storms is infiltrated in
the ground rather than discharged into a
surface water body. (I)
Infiltration Trench - is an excavated
trench (3 to 12 feet deep), backfilled with
stone aggregale, and lined with filler
fabric. (23)
It is used to treat a small portion ofthe
runoff by detaining storm waler for short
periods until it percolates down lo the
groundwater table. (21)
Useful life is usually around 10 years.
(20)
*potential loss of infiltrative
capaciiy. (1)
*applicability depends on
specific site
characteristics/opportunities
(slope, soil types, proximity
to water lable). (23)
*potential groundwater
contamination. (1)
*noi suitable for sites that
contain chemical or
hazardous material. (23)
*may need lo be preceded
by appropriaie pretreatment.
(23)
•relatively shorl life span.
(23)
•efficient removal of
pollutants. (1)
•can recharge groundwater
supplies. (2)
•provides localized
streambank erosion control.
(2)
•easy to fit inlo unutilized
areas of developmenl sites.
(2)
•an effective runoff
control. (I)
•increases baseflow in
nearby streams. (23)
•Low land use
requirement. (20)
• nitrogen compounds
40% lo m%. (2)
• phosphorus compounds
40% to 80%. (2)
• combined nitrogen and
phosphorus compounds
45% lo 75% (depending on
design). (8)
• total suspended solids
75%. (20)
•tolal phosphorous 60%'.
(20)
• total nitrogen 55%. (20)
•COD 65%. (20)
• Lead 65%. (20)
• Zinc 65%.. (20)
• $4,900/aci-e
(prorated using
ENR index from
1992 cost). (5)
* $3.6 to
$10.70/cubic feet
storage (prorated
using ENR index
from 1986 cost).
(20)
* $l,800/acre/year
(prorated using
ENR index from
1992 cost). (5)
• 9% of Capital
Cost (20)
Pond (Basin) - consist of shallow, flat
basins excavated in pervious ground, with
inlet and outlet structures to regulate
How. (19)
Useful Life is usually around 25-years.
(20)
•potential loss of infiltrative
capacity. (1)
•low removal of dissolved
pollutants in very coarse
soils. (1)
•possible nuisance (odor,
mosquito). (2)
•frequent maintenance
requirement. (2)
•risk of groundwater
contamination. (1)
• High land use requirement.
(20)
•achieves high levels of
particulate pollutant
removal. (1)
• can recharge groundwater
supplies. (2)
•an effective runoff
ct)nlrol. (I)
•can serve tributary areas
up to 50 acres. (I)
•provides localized
streambank erosion control.
(2)
•cost effective. (2)
• nitrogen compounds
40%. to 80%.. (2)
• phosphorus compounds
40'/<. lo 80%.. (2) r
• combined nitrogen and I
phosphorus compounds ^
A5% to 75% (depending on
design). (8)
• total suspended solids
75%. (20)
•total phosphorous 65%.
(20)
• total nitrogen 60%.. (20)
•COD 65%.. (20)
• Lead 65'/-. (20)
• Zinc 65%. (20)
* $36,900/million
gallons (prorated
using ENR index
from 1992 cost).
(5)
• $0.60 to
$1/cubic feet
storage (prorated
using ENR index
from 1986 cost).
(20)
• $i.200/milli()n
gallons/year
(prorated using
ENR index from
1992 cost). (5)
• 7% of Capilai
Cost (20)
Nationwide Examples of Treatment Control (Structurai) Best Management Practices (BMPs)
Treatment Control (Source)
Porous Pavement - is an alternative lo
conventional pavement whereby runoff is
diverted through a porous asphalt layer
and into an underground stone reservoir.
(10)
Useful life is around 10 years. (20)
Limitations
potential loss of infiltrative
capacity. (1)
J'75% failure rate due to
clogging, resurfacing or just
failure after construction.
(10)
>high maintenance -
requires special vacuum
sweeping or jet hosing. (10)
>may require twice as much
material as without porous
pavement to achieve the
needed strength. (10)
J>unsuitable in fill sites and
steep slopes. (5)
> potential risk of
groundwater contamination.
(1)
•limited efficiency (6
months). (23)
Benefits
achieves high levels of
pollutant removal. (1)
/i groundwater recharge. (2)
> localize streambank
erosion control. (2)
> reduced land
consumption. (2)
J>elimination of curbs and
gutters. (2)
Jl safer driving surface. (2)
Removal Efficiency
• nitrogen compounds
60% to 80%. (2)
• phosphorus compounds
40% to 80%. (2)
•nitrogen and phosphorus
compounds 45%) to 75%
(depending on design). (8)
• sediment 82 to 95%. (23)
• total phosphorus
compounds 65%. (23)
• tolal nitrogen compounds
80 to 85%. (23)
• total suspended solids
90%. (20)
•total phosphorous. 65%
(20)
• tolal nitrogen 85%. (20)
•COD 80%. (20)
• Lead 100%. (20)
• Zinc 100%. (20)
Capital Cost
(approximate)
• $123,000/acre
(prorated using
ENR index from
1992 cost). (5)
* $2.10/square
feet (prorated
using ENR index
from 1987 cost)
(incremental cost
beyond the
conventional
asphalt pavement).
(20)
O&M Cost
(approximate)
• $250/acre/year
(prorated using
ENR index from
1992 cost). (5)
• $0.14/square
feel/year (prorated
using ENR index
from 1987 cosi).
(incremental cost
beyond the
conventional
asphalt pavement).
(20)
• -$0.07/ft' feel
(prorated using
ENR index from
1981 cost)
(incremental cost
beyond the
conventional
asphalt pavement)
(20)
Concrele Grid Pavement - are lattice grid
structures wilh grassed or pervious
malerial placed in the grid openings. (1)
Useful life is usually around 20 years.
(20)
J> requiie regular
maintenance. (20)
Jinot suitable for high traffic
areas. (20)
J>potential groundwater
contamination. (20)
J>only feasible where soil is
permeable. (20)
groundwater recharge.
(20)
/>can provide peak How
control. (20)
•total nitrogen 90%. (20)
• total phosphorus
compounds 90%. (20)
• total suspended solids
90%.. (20)
•COD 90%. (20)
• Lead 90%.. (20)
• Zinc 90%. (20)
• $1.7 - $3.5/tr
(prorated using
ENR index from
1981 cost)
(incremental cost
beyond the
conventional
asphalt pavement)
(20)
Infiltration Drainfields - a system
composed ofa pretreatment structure, a
manifold system, and a drainfield. (28)
•high maintenance when
sediment loads are heavy.
(28)
•short life span if not well
maintained. (28)
•nol suitable in regions wilh
clay or silly soils. (28)
•anaerobic conditions could
clog the soil. (28)
•potential groundwater
contamination. (28)
Jl groundwater recharge.
(28)
•used to control runoff.
(28)
• depends on design - little
monitoring data currently
available. Potentially
100% of pollutant could be
prevented from entering
surface water. (28)
Approx. $72,000
for a drainfield
with dimensions:
100 ft long, 50
feel wide, 8 feet
deep with 4 ft
cover. (28)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Benefits Removal Efficiency Capital Cost
(approximate)
O&M Cost
(approximate)
Wet Detention Ponds - small artificial
impoundments wilh emergent wetland
vegetation around the perimeter designed
for the removal of particulate matter and
dissolved nutrients. (19)
Useful life is around 50 years. (20)
Jl maintaining oxygen supply
in the pond. (1)
Jineed of supplemental
water lo maintain water
level. (1)
Jiland constraints, infeasible
in dense urban areas. (1)
Jl local climate might affect
biological uptake. (27)
Jieventual need for costly
sediment removal. (2)
• potential nuisance
(mosquito, odor, algae). (2)
•potential stratification and
anoxic conditions. (27)
Jiachieves high levels of
soluble and organic
nutrient removal. (2)
Jicreation of local wildlife
habitat. (2)
Jl decrease potential for
downstream flooding. (27)
Jl recreational and
landscape amenities. (2)
Jidecrease polenliai
downstream stream bank
erosion. (19)
• nitrogen 20% to 60%. (2)
• phosphorus 40% lo 80%..
(2)
• nitrogen & phosphorous
30% to 70% (depending on
volume ratio). (8)
• total suspended solids
50%. to 90'/- (27) & 60%.
(20).
• total phosphorus 30% to
90%. (27) & 45% (20).
• total nitrogen 35%.. (20)
• soluble nutrients 40% to
80%. (27)
• lead 70%. to 80% (27) &
75% (20).
• zinc 40% to 50% (27) &
60% (20).
• COD 40%. (20)
$17.50 to $35 per
cubic meter of
storage area (27)
3 lo 5 percent of
construction cost
per year (27)
Wetlands - constructed wetlands are a
single stage treatment system consisting
ofa forebay and micro pool with aquatic
plants. They remove high levels of
particulate, as well as some dissolved
contaminants. (19)
Useful life is around 50 years. (20)
Jineed of supplemental
water to mainlain waler
level. (1)
Jl potential nutrient release in
the winter. (19)
Jl reduction in hydraulic
capacity wilh plant growth.
(19)
Jl wetland area less than 2%
of watershed area. (10)
•potential groundwater
contamination. (26)
• high land requirements.
(20)
Jl passive recreation and
wildlife support. (1)
Jl improve downstream
waler and habitat quality.
(26)
Jl flood attenuation. (26)
Jiachieves high levels
pollutant removal. (I)
• total suspended solids
67% (26) & 65%. (20).
• Iotal phosphorus 49%
(26) & 25% (20).
• total nitrogen 28%. (26) &
20%. (20).
• organic carbon 34%. (26)
• COD 50%. (20)
• petroleum hydrocarbons
87%. (26)
• cadmium 36%.. (26)
• copper 41%. (26)
• lead 62% (26) & 65%
(20).
• zinc 45% (26) & 35%
(20).
• bacteria 77%. (26)
$26,000 to
$55,000 per acre
of wetland. (26)
2 percent of
construction cost
per year. (26)
Nationwide Examples of Treatment Controi (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Benefits Removal Efficiency Capital Cost
(approximate)
O&M Cost
(approximate)
Biofiiters - Systems designed to pass
storm water runoff slowly over a
vegetated surface iri the form of a swale
or strip lo filter pollutants and to infiltrate
the runoff (19)
Biorelenlion - system designed to treat
runoff The runoff is conveyed as sheet
flow to the treatment area, which consists
ofa grass buffer strip, sand bed, ponding
area, organic layer or mulch layer,
planting soil, and plants. (33)
•cold climate may hinder
infiltrative capacity. (33)
•nol suitable for slopes
greater than 20 percent. (33)
•clogging may occur in high
sediment load areas. (33)
•enhance quality of
downstream water bodies.
(33)
•improves area's
landscaping. (33)
•provide shade and wind
breaks. (33)
Jl design to convey runoff
of 2 year storm, with
freeboard of 10 year storm.
(19)
• low land requirement.
(20)
Jisuilable for small
residential areas. (1)
Jican removes particulate
pollutants at rales similar to
wel ponds. (1)
•reduction of peak flows.
(29)
•lower capilai cost. (29)
•promiMion of runoff
infiltration. (29)
• low land requirements.
(20)
• total Phosphorus 70 to
83%. (33)
• metals (copper, lead,
zinc) 93 to 98%. (33)
• TKN 68% to 80%. (33)
• total suspended solids
90%. (33)
• organics 90%. (33)
• bacteria 90%. (33)
$500 for new
development of a
bioretention,
$6,500 for
retrofitting a site
into a bioretelion
area (33)
Vegetated Swale - is a broad, shallow
channel (typically trapezoidal shaped)
wilh a dense stand of vegetation covering
the side slopes and bottom. (29)
Useful life is around 50 years. (20)
Jl generally incapable of
removing nutrients. (2)
•can become drowning
hazards, mosquito breeding
areas. (29)
J>nol appropriate for steep
topography, very flat grades.
(29)
Jitributary area limited to a
maximum of 5 acres. (19)
Jidilficull to avoid
channelization. (19)
•ineffective in large storms
due to high velocity llows.
(29)
• nitrogen 0 to 60%. (2)
• total nitrogen 10%. (20)
• phosphorus 0 to 60% (2)
• total phosphorus 9% (29)
& 20% (20).
• COD 25%. (20)
• oxygen demanding
substances 67%. (29)
• total suspended solids
81 % (29) & 60% (20).
• nitrate 38%. (29)
• hydrocarbons 62%. (29)
• cadmium 42%.. (29)
• lead 67% (29) & 70%.
(20).
• zinc 71% (29) & 60%
(20).
• copper 51%.. (29)
•$6.80 to $12.50
per linear foot
(prorated using
ENR index from
1987 cost). (29)
•$10.80 to $63.40
per linear foot
(prorated using
ENR index from
1991 cost). (29)
• typical total for
a 1.5 ft. deep, 10 ft
wide, 1,000 fl long
Low - $8,100
Moderate -
$14,870
High-$21,640
Prorated using
ENR index from
1991 cosO.
(29)
• $0.73 - $0.95
per linear foot
(prorated using
ENR index from
1991 cost), (29)
• $ I/linear foot
9piorated using
ENR index from
1987 cost). (20)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limilatlons Benefits Removal Efficiency Capital Cost
(approximate)
O&M Cost
(approximate)
Iiifillralion (Vegetative Filter) Strip - are
broad surfaces with a full grass cover that
allows storm water to tlow in a relatively
thin sheets (21)
Useful life is around 50 years (20).
•sheet flow may be difficult
to attain. (1)
•not appropriate for steep
slopes. (19)
•tributary area limited to 5
acres. (19)
•suitable for parking lots.
(1)
•slows runoff flow. (1)
•removes particulate
pollutants. (1)
• nitrogen Oto 40%. (2)
• phosphorus 0 to 40%. (2)
• total suspended solids
65%. (20)
• total phosphorous 40%.
(20)
• tolal nitrogen 40%. (20)
• COD 40%. (20)
• lead 45%. (20)
• zinc 60%.. (20)
• $3,100/acre
(prorated using
ENR index from
1992 cost).
(5)
• $310/acre/yr
(prorated using
ENR index from
1992 cost). (5)
• $139 to
$l,100/acre/year
(prorated using
ENR index from
1987 cost). (20)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Beneflts Removal Efflciency Capital Cost O&M Cost
(approximate) (approximate)
Extended Detention Basins - consist ofa •occasional nuisance in •creation of local wildlife • nitrogen 20% lo 60%. $123,000/million • $l,230/miliion
settling basin with an outlet sized lo inundated portion. (19) habitat. (2) (2) gallons gallons/year
remove particulate matter by slowly •inability lo vegetation may •recreational use in • phosphorus 20% to 80% (prorated using (prorated using
releasing accumulated runoff over a 24 to result in erosion and re-inundated portion. (2) (2) & 10% to .30%. (10) ENR index from ENR index from
40 hour period. "Dry" detention basins suspension. (1) •can remove soluble • nitrogen and phosphorus 1992 COSI). 1992 cost).
may be designed to empty between •limited orifice diameter nutrients by shallow marsh 30% to 70% (depending on (5) (5)
usages. (19) preclude use in small or permanent pool. (2) volume ratio). (8) • 4% of capilai
Useful life is usually 50 years. (20) watersheds. (1) •suitable for sites over 10 • soluble nutrients - low or cost. (20)
•requires differential in acres. (10) negative. (10)
elevalion al inlet and outlet. •temporary storage of • total suspended solids
(1) runoff (1) 45% (20) & 88% (44).
•frequent sediment •no need of supplemental • nitrate 15% (44).
maintenance. (19) water. (1) • nitrite 61% (44).
• High land requirement. •protection for downstream • oil and grease 56%.. (44)
(20) channel erosion. (2) • fecal coliform 45%. (44)
total petroleum
hydrocarbons 17% to 20%.
(44)
• TKN 40%. (44)
• ammonia 5%.. (440
•total phosphorous 25%
(20) & 57% (44).
• tolal nitrogen 30%. (20)
•COD 20%. (20) & (44).
• lead 20%. (20) & 55%
(44).
• zinc 20% (20) & 47%
(44).
• chromium 68%. (44)
• copper 37%.. (44)
• nickel 62%. (44)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Beneflts Removal Efflciency Capital Cost
(approximate)
O&M Cost
(approximate)
Modular TreatinenI Systems
StormTreal"^ System (STS) - treaimenl
technology consisting ofa series of
sedimentation chambers and constructed
wetlands. The 9.5 feet diameter recycled
polyethylene modular treats storm waler
with sedimentation chambers, where
pollutants are removed through
sedimentation and flltration, then the
water is conveyed to a surrounding
constructed wetland. Vegetation in the
wetiand varies depending on local
conditions. Because the system is
relatively new, there is no data available
on lifetime ofthe system, ll is estimated
lhat the plants and the gravel in the
system need to be replaced every 10-20
years. (32)
•may require modiflcations
to function in different
environments. (32)
• relatively new and remains
lo be tested in differeni
geographical locations.
•proiect groundwater by
removing pollutants prior
to inflltration. (32)
•high removal rates. (32)
•spill containment feature.
(32)
•soil types and high water
lable won't limit
effectiveness. (32)
• fecal coliform bacteria
97%. (32)
• tolal suspended solids
99% (32)
• COD 82%. (32)
• total dissolved nitrogen
77%.. (32)
• phosphorus 90%. (32)
• total petroleum
hydrocarbons 90%. (32)
• lead 77%. (32)
• chromium 98%. (32)
• zinc 90%. (32)
$4,900 per unit +
$500 to $ 1,000
installation cost +
$350 to $400 for
additional material
(32)
$80 to $120 per
tank for removal
of sediment (32)
Hydrodynamic Separators - are flow-
through structures wilh a settling or
.separation unit to remove sediments and
olher pollutants that are widely used.
With proper upkeep, useful life is over 30
years. (25)
Downstream Defender^'^ - designed to
capture settleable solids, floatables and oil
and grease. It utilizes a sloping base, a dip
plate and internal components to aid in
£ollutant removal. (25)
* requires frequent
inspections and maintenance
is site-specific. (25)
Can achieve 90%' particle
removal for flows from
0.75 cfs to 13 cfs (25)
$10,000 to
$35,000 per pre
cast unit (23)
Continuous Deflection Separator (CDS) -
pre cast units placed downstream of
freeway drain inlets to capture sediment
and debris. These underground units
create a vortex of water that allows waler
to escape through the screen, while
contaminants are deflected into the sump.
(21)
• suitable for gross pollutant
removal. (21)
Jl inlended to screen litter,
flne sand and larger
particles. (2 1)
Jiact as a flrst screen
influence for trash and
debris, vegetative malerial
oil and grease, heavy
metals. (21)
oil and grease - 77% (34) $2,300 to .$7,200
per cubic feet
second capacity
(23)
Nationwide Examples of Treatment Controi (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Beneflts Removal Efflciency Capital Cost
(approximate)
O&M Cost
(approximate)
Continuous Deflection Separator (CDS)
with Sorbenls. Applicalion of differeni
types of sorbents in the CDS units.
OARS^^ - is a rubber type off sorbent
(34)
Rubberizer - is composed of a
mixture of hydrocarbon polymers
and additives. (34)
Aluminum Silicate:
Xsorb^^ is made from a natural
blend of silica minerals, which
when expanded in our unique
manufacturing process, make a
while granular material that
absorbs spills instantly on
contact (web)
Sponge Roli^'^ - primarily sold as
a soil bulking agent (34)
Nanoftber'^^* - is a polypropylene
adsorbent. (34)
• requires frequent
inspections and maintenance
is site-speciflc. (25)
•sorbents remove many
times their own weight (34)
•could be used oil spill
control. (34)
OARS:
oil and grease - 82%, 83%,
86%, 94% (34)
Rubberizer:
oil and grease 86%. (34)
Xsorb:
oil and grease 79%. (34)
Sponge Rok:
oil and grease 41%. (34)
Nanofiber:
oil and grease 87%. (34)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source)
Stormceptor® - This system is a
stormwater interceptor that efficiently
removes sediment and oil from
stormwater runoff and stores these
pollutants for safe and easy removal.
Units are available in prefabricated sizes
up lo 12 feet in diameter by 6 to 8 feel
deep. They re designed to trap and retain
a variety of non-point source pollutants,
using a by-pass chamber and treatment
chamber. A fiberglass insert separates the
upper (by-pass) and lower
(separation/holding) chambers. (25)
Limitaiions
• requires frequent
inspections and maintenance
is site-specific. (25)
Beneflts
•use for redevelopment
projects of more than 2,500
sq. feel where there was no
pervious storm water
managemeni. (25)
•projects that double the
impervious layer. (25)
•easy to design in new or
relroflt applications. (35)
•inexpensive lo service and
mainlain. (35)
•internal bypass prevents
release of trapped
pollutants. (35)
•Ideal for highways,
industrial properties, gas
stations, parking lots and
sites where there is a
potential for oil or chemical
spills.
Removal Efflciency
• tolal suspended solids
80%. (35)
• free oils 95%. (35)
• oil 98.5%. (36)
• inorganic sediment 80%.
(36)
• organic sediment 70%.
(36)
• total suspended solids
51.5%. (36)
• oil and grease 43.2%.
(36)
•zinc 39.1%. (36)
• total organic carbon
31.4%. (36)
• chemical oxygen demand
26.0%. (36)
• lead 51.2%. (36)
• chromium 40.7%.. (36)
• copper 21.5%. (36)
• iron 52.7%. (36)
• calcium 17.9%. (36)
Capital Cost
(approximate)
$7,600 to $33,560
per unit (23)
O&M Cost
(approximate)
$l,000/year per
structure (23)
Voriechs'^^ - a major advancement in oil
and grit separator technology, Vortechs
units removes grit, contaminated
sediments, heavy metals, and oily floating
pollutants from surface runoff II is a
stormwater treatment system consisting of
four structures to treat stormwater: a
baffle wall, a grit chamber, an oil
chamber and a flow control chamber.
This system combines swirl-concentrator
and flow-control technologies. (25)
•most effective when
separation of heavy
paniculate or floatable from
wet weather runoff (25)
•suspended solids are not
effectively removed. (25)
• requires frequent
inspections and mainlenance
is site-specific. (25)
•suited for areas wilh
limited land available (25)
•good for "holspols" such
as gas stations (high
concentrations). (25)
•able to treat runoff flows
from 1.6 cfs to 25 cfs. (25)
• totai suspended solids
84%. (37)
$10,000 to
$40,000 per unit
(nol including
installation) (23)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitaiions Beneflts Removal Efflciency Capilai Cost
(approximate)
O&M Cost
(approximate)
Multi-Chambered Treatment Trains
(MCTT) - consist ofa ihree trealment
mechanisms in three different chambers.
1) catch basin - screening process to
remove large, grit sized material, 2)
settling chamber - removing settleable
solids and associated constituents with
plate separators and sorbent pads, 3)
media fliter - uses a combination of
sorption (layers of sand and peat covered
by fliter fabric) and ion exchange for the
removal of soluble constituents. (21)
•high mainlenance - require
renewing sorbent pads,
removing sediment,
replacing clogged media.
(21)
•treats storm water at
critical source areas wilh
limited space. (21)
• toxicity 70%. to 100%.
(24)
• chemical oxygen demand
0%. to 100% (24)
• total suspended solids
70% to 90%. (24)
• approx.
$375,000 to
$900,000
(depending on
drainage area)
Media Filtration - these are usually two
or three stage constructed treatment
systems, composed ofa pretreatment
settling basin and a fliter bed containing
fliter media (and a discharge chamber).
(19)
Sand Filter - the Alter is designed lo hold
and treat the flrst one half inch of runoff
and the pollutant removal ability ofthe
sand fliter has been found to be very
good. (3)
•not effective treating liquid
or dissolved pollutants (19)
Jl routine mainlenance
requirement. (19)
Jisigniflcant headloss. (19)
Jl severe clogging polenliai.
(19)
•media may be replaced 3 to
5 years. (30)
•climate conditions may
limil fllter's performance.
(.30)
Jihigh removal rates for
sediment, BOD, and fecal
coliform bacteria. (30)
•can reduce groundwater
contamination. (30)
Jl requires less land, can be
placed underground. (19)
Jisuilable for individual
developments. (1)
Jiminimum depth of 18
inches. (1)
Jitributary areas of up lo
100 acres. (19)
• fecal coliform 76%. (30)
• BOD 70 %. (30)
• tolal suspended solids
70 %. (30)
• total organic carbon 48%.
(30)
• tolal nitrogen 21'}(.. (30)
• total phosphorus 33'/-.
(-30)
• Lead 45%.. (30)
• zinc 45%. (30)
• iron 45%. (30)
• $18,500 (1 acre
drainage area)
(1997). (30)
• $6,940 to
$11,600 (less than
1 acre - cast in
place) (prorated
from 1997 prices
using ENR index).
(30)
• sand fliter vaull
$ 1,790 (prorated
from 1997 prices
using ENR index).
(18)
• sand fliter basin
$3,370 (prorated
from 1997 prices
using ENR index).
(18)
• 5 percent of the
initial construction
cost. (30)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Beneflts Removal Efficiency Capital Cost
(approximate)
O&M Cost
(approximate)
Activated Carbon - has long been used in
the chemical process industry and in
hazardous waste cleanup as an effective
method for removing trace organics from
a liquid. (3)
•heavy maintenance
requirement. (19)
•severe clogging potential.
(19)
•limited by the number of
adsorption sites in the
media. (3)
•small net surface charge
and ineffective at removing
free hydrated metal ions. (3)
•can be placed
underground. (19)
•less space required. (1)
•effective in removing
trace organics from liquid.
(3)
•suitable for individual
developments. (1)
• $l/lbor$315/cy
(prorated from
1997 prices using
ENR index).
(18)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitaiions Beneflts Removal Efflciency Capilai Cost O&M Cosi
(approximate) (approximate)
Composted Leaves - made from yard •heavy maintenance •can be placed * tolal suspended solids • $130/cy • $2,400/year
waste, primarily leaves, have been requirement. (19) underground. (19) 84'/-(3),-155'/- to 72% (prorated from (prorated from
advertised to have a very high capacity •severe clogging potential. •no vegetation required. (22). 1997 prices using 1998 prices using
for adsorbing heavy metals, oils, greases, (19) (19) • petroleum hydrocarbons ENR index). ENR index). (22)
nutrients and organic toxins due to the •in some cases, negative •smaller land area required. 87'/-(3), 4% to 64% (22). (18)
humic content ofthe compost. (3) removal efflciencies with (3) • chemical oxygen demand • $27,000 to treat
increased loads have been •suitable for individual 67% (3), 32% lo 38% (22). 1 cfs (prorated
reported. (22) developments. (1) • total Phosphorus 40% (3) from 1998 prices
& -320% to 28'/- (22). using ENR index).
•TKN-133% to 43%. (22) (22)
• fecal coliform 6% to
80%. (22)
• t)il and grease 0% to
44'^. (22)
• total petroleum
hydrocarbons 33% to 64%.
(22)
• ammonia 41% to 64%.
(22)
• nitrate-172%. to 7%. (22)
• nitrite -233% to 29%.
(22)
• chromium 0'/- to 25%.
(22)
• copper 67% (3) & 4% to
9% (22).
• zinc 88'/- (3) & 46%. to
65% (22).
• aluminum 87'/-. (3)
• nickel 33% lo 50'/-. (22)
• lead 0% to 17'/-. (22)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Trealment Control (Source) Limitations Beneflts Removal Efflciency Capital Cost
(approximate)
O&M Cost
(approximate)
Peat Moss - is partially decomposed
organic material, excluding coal, that is
formed from dead plant remains in waler
in the absence of air. The physical
structure and chemical composition of
peat is determined by the types of plants
from which it is formed. Peat is
physically and chemically complex and is
highly organic. (3)
•heavy maintenance
requirement. (19)
•severe clogging potential.
(19)
•can have a high hydraulic
conductivity. (3)
•can be placed
underground. (19)
•no vegetation required.
(19)
•smaller land area required.
(3)
•polar and has a high
speciflc adsorption for
dissolved solids. (3)
•excellent natural capaciiy
for ion exchange. (3)
•excellent substrate for
microbial growth and
assimilation of nutrients
and organic waste malerial.
(3)
$25 to$105/cy
(prorated from
1997 prices using
ENR Index). (18)
Peat-Sand FUter - man made filtration
device, has good grass cover on the top
underlain by twelve to eighteen inches of
peat. The peat layer is supported by a 4
inch layer of peat and sand mixture which
supported by a 20 to 24 inch layer of flne
to medium sand. Under the sand is gravel
and the drainage pipe. (3)
•heavy maintenance
requirement. (19)
•severe clogging potential
(19)
•can be placed
underground. (19)
•less space required (1)
•suitable for individual
developments. (1)
•works best during
growing season as grass
cover can provide
additional nutrient removal
(3)
• suspended Solids 90'/-
(3) & 80% (20).
• total phosphorus 70% (3)
& 50% (22).
• total nitrogen 50% (3) &
35% (20).
• BOD 90%. (3)
• bacteria 90%. (3)
• trace metals 80%.. (3)
• lead 60'/-. (20)
• zinc 65%.. (20)
• COD 55%. (20)
$6.50 per cubic
foot of malerial
(prorated from
1990 prices using
ENR index). (20)
7 % of
conslruclion cost.
(20)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Beneflts Removal Efficiency Capital Cost
(approximate)
O&M Cost
(approximate)
Waler Quality Inlets - commonly known
as oil/grit or oil/water separators. These
devices typically consist of a series of
chambers, a sedimentation chamber, an
oil separation chamber and a discharge
chamber. (31)
Useful life is usually 50 years. (20)
•limited drainage area (1
acre or less). (31)
•high sediment loads can
interfere ability lo separate
oil and grease. (31)
•limited hydraulic and
residual storage. (31)
•frequent maintenance. (31)
•residual may be considered
too toxic for landflU
disposal. (31)
•recommended oil/water
separators be used for spill
control as their primary
application. (42)
•re-suspension of pollutants.
(36)
• small flow capacity. (31)
•reduction of hydrocarbon
contamination. (31)
•efl'ectively trap trash,
debris, oil and grease (31)
•ideal for small, highly
impervious area. (31)
•ideal for mainlenance
stations. (36)
• low land requirement.
(20)
• sediments 20% to 40%.
(31)
• efficiency directly
proportional to discharge
rate. (31)
• total suspended solids
15% to 35'/-. (20)
• tolal phosphorous 5%.
(20)
• total nitrogen 5% to 20%.
(20)
• COD 5%.. (20)
• lead 15'/-. (20)
• zinc 5%. (20)
,$5,900 to $18,900
for cast in place
water quality
inlets (prorated
from 1993 prices
using ENR Index),
(31)
Catch Basin Inlet Devices - devices lhal
are inserted into storm drain inlets to fliter
or absorb sediment, pollutants, and oil
and grease (21)
* not feasible for larger lhan
5 acres. (20)
• high removal efflciency
for large particles and
debris for pretreatment.
(20)
• low land requirement.
(20)
• flexibility for relroflt of
exisling systems. (20)
Stream Guard Inserts - are sock-type
inserts lhat allow collected water lo fliter
ihrough the geotextile fabric. (21)
•mainlenance includes
removal of sediment and
debris. (21)
•conflgured to remove
sediment, constituents
adsorbed lo sediment, and
oil and grease. (2 1)
approx. $50,000 to
$100,000 per
catch basin. (21)
Fossil Filter Inserts - are trough-type of
inserts filled with granular amorphous
alumina silicate media. Removes
pollutants through sorption. (21)
•maintenance includes
removal of scdimeiil and
debris. (21)
•configured to remove
sediment, consliliienis
adsorbed lo sediment, and
oil and grease. (21)
approx. $50,000 to
$100,000 per
catch basin. (21)
OARS'^' - is a rubber type of sorbent
insert (34)
• free oil and grease 88'X.
to 91'/-. (.39)
• emulsified oil and grease
3%. (39)
Nanoflber^^ - is a polypropylene
adsorbent type of insert. (34)
• free oil and grease 86%,
92'/-, 78'/-, 85%. (.39)
Nationwide Examples of Treatment Control (Structural) Best Management Practices (BMPs)
Treatment Control (Source) Limitations Beneflts Removal Efflciency Capilai Cost
(approximate)
O&M Cost
(approximate)
Aluminum SUicate:
Xsorb'^^ is made from a natural
blend of silica minerals, which
when expanded in the unique
manufacturing process, makes a
white granular material that
absorbs spills instantly on
contact.
Sponge Rok™ - primarily sold as
a soil bulking agent (34)
• free oil and grease 88%,
91%, 94%, 89%. (39)
• emulsifled oil and grease
0%. (39)
Curb Inlet Drain Diaper Insert - sorbent
type diaper placed at the catch basin
insert. (40)
$125 per unit. (40)
Storm Clenz Filler and Multi CeU Flow
Through F(7/er - developed by Best
Management Technologies, the fllters are
used typically in maintenance facilities
and staging areas were sediment and
hydrocarbons are present. (41)
• multi cell flow
through fllters -
$786 to $1233
depending on pipe
size (6" to 12")
• storm clenz
fllters - $339 to
$702 depending
on fliter insert
size. (41)
• flow through
fliter absorbents
$24 to $44
depending on size.
• storm clenz
absorbents $24 to
$ 54 depending on
size. (41)
Some Examples of Temporary Erosion and Sediment Control BMPs - (typically used during construction
activity)
Temporary Seeding of Stripped Areas -
The establishment ofa temporary
vegetative cover on disturbed areas by
seeding with rapidly growing plants. This
provides temporary soil stabilization to
areas which would remain bare for more
than seven days where permanent cover is
not necessary or appropriate. (42)
•Temporary seeding is only
viable when there is a
sufflcient window in time
for plants to grow and
establish cover. During the
establishment period the
bare soil should be protected
with mulch and/or plastic
covering. (42)
•If sown on subsoil, growth
may be poor unless heavily
fertilized and limed
Because over-fertilization
can cause pollution of
stormwater runoff olher
practices such as mulching
alone may be more
appropriate. The potential
for over-fertilization is an
even worse problem in or
near aquatic systems. (42)
•Once seeded, areas cannot
be used for heavy traffic.
(42)
•May require regular
irrigation to flourish.
Regular irrigation is not
encouraged because of the
expense and the potential for
erosion in areas that are not
regularly inspected. The use
of low maintenance native
species should be
encouraged, and planting
should be timed to minimize
the need for irrigation. (42)
•This is a relatively
inexpensive form of
erosion control bul should
only be used on siles
awaiting permanent
planting or grading. Those
sites should have
permanent measures used.
(42)
•Vegetation will nol only
prevent erosion from
occurring, but will also trap
sediment in runoff from
other parts of the site. (42)
•Temporary seeding offers
fairly rapid protection lo
exposed areas. (42)
Mulching and Matting - Application of
plant residues or olher suitable malerials
to the soil surface. This provides
immediate protection to exposed soils
during the period of short construction
delays, or over winter months through the
application of plant residues, or other
suitable materials, to exposed soil areas.
Mulches also enhance plant establishment
by conserving moisture and moderating
soil temperatures. Mulch helps hold
fertilizer, seed, and topsoil in place in the
presence of wind, rain, and runoff and
maintains moisture near the soil surface.
(42)
•Care must be taken to
apply mulch at the specified
thickness, and on steep
slopes mulch must be
supplemented with netting.
(42)
•Thick mulches can reduce
the soil temperature,
delaying seed germination.
(42)
•Mulching offers instant
protection to exposed areas.
(42)
•Mulches conserve
moisture and reduce the
need for irrigation. (42)
•Neither mulching nor
matting require removal;
seeds can grow through
them unlike plastic
coverings. (42)
Plastic Covering - The covering with
plastic sheeting of bare areas, which need
immediate protection from erosion. This
provides immediate temporary erosion
protection to slopes and disturbed areas
that cannot be covered by mulching, in
particular during the specifled seeding
periods. Plastic is also used to protect
disturbed areas, which must be covered
during short periods of inactivity to meet
November 1 to March 31 cover
requirements. Because of many
disadvantages, plastic covering is the least
preferred covering BMP. (42)
•There can be problems
with vandals and
maintenance. (42)
•The sheeting will resuli in
rapid, 100 percent runoff
which may cause serious
erosion problems and/or
flooding at the base of
slopes unless the runoff is
properly intercepted and
safely conveyed by a
collecting drain. This is
strictly a temporary
measure, so permanent
stabilization is still required.
•The plastic may blow away
ifit is not adequately
overlapped and anchored.
(42)
•Ultraviolet light can cause
some types of plastic to
become brittle and easily
lorn. (42)
•Plastic must be disposed of
at a landfill; it is not easily
degradable in the
environment. (42)
•Plastic covering is a good
meihod of protecting bare
areas, which need
immediate cover and for
winter plantings. (42)
•May be relatively quickly
and easily placed. (42)
Nationwide Examples of Source Control (Non-Structural) Best Management Practices (BMPs)
Source Control (5) Benefit (5) Capilai Cost (5) O&M Cost (5)
Minimizing Effects from Highway Deicing
Public Education (billing inserts, news
releases, radio announcements, school
programs)
JiCan reduce improper disposal of paints and
chemicals.
.$200,000/yr(1992) $257,000/yr(1992)
r V
Employee Training - teaches employees about
storm water management, potential sources of
contaminants, and BMPs. (43)
Jilow cost and easy lo implement storm water
management BMPs. (43)
Litter Control Jl Reduce polenliai clogging.
Jl proper disposal of paper, plastic and glass.
$20 per trash cans (1992) $l6/acre/yr(1992)
Recycling Program Jl reduction in potential clogging and harmful
discharge.
$200,000/yr $350,000 per 300,000
people
"No Littering" Ordinance Jiprevents litter from enter storm drain. $20,000 potential self
supporting
Identify and Prohibit Illegal or Illicit discharge
10 Storm Drain
Jihall hazardous and harmful discharge. $2/acre (assumes 1
system monitored every
5 sq. miles)
$50/acre/yr (assumes
TV inspection)
Slreet Sweeping - Two types of street
sweepers are available for removal of solids
from highway surfaces. The commonly used
design is a mechanical street cleaner that
combines a rotating gutter broom with a large
cylindrical broom to carry the malerial onto a
conveyor belt and inlo a hopper.
The vacuum assisted sweepers, found to
potentially remove more flne particles from
the impervious surface, are impracticable due
to their slow speed in highway maintenance
operations. (42)
Jl reduction in potential clogging storm drain material.
Jisome oil and grease control.
N/A $0.83/acre/yr
' i— ——
Sidewalk Cleaning Jl reduction of material entering storm drain. N/A $60/acre/yr
Clean and Maintain Storm Drain Channels Jl prevent erosion in channel.
Jl improve capaciiy by removing sedimentation.
Jl remove debris toxic to wildlife.
N/A $21/acre/yr
Clean and Maintain Storm Inlet and Catch
Basins - Inlets, catch basins, and manholes are
to be periodically inspected and cleaned out
using a vacuum truck. (42)
Jl removes sedimentation.
Jimay prevent local flooding.
N/A $21/acre/yr
Snow and Ice Control Operations - Snow
control operations consist of removing
accumulated snow from the traveled
way, shoulders, widened areas and public
highway approaches within the righl-of-way,
(42)
Jl removes snow/ice before it requires ice control
operalions. (42)
Clean and Inspect Debris Basin Jl flood control.
Jl proper drainage and prevent flooding.
N/A $21/acre/yr
Table References
1. Camp Dresser & McKee, et al. 1993. California Stonn Water Best Management Handbook. Prepared for Storm
Water Quality Task Force. 4-8:4-77, 5-3:5-69.
2. Scheuler, Thomas R. 1987. ControUing Urban Runoff: A Practice Manual for Planning and Designing Urban
BMP's. Prepared for Washington Metropolitan Water Resources Board. 2.11:2.14, 5.1:7.25.
3. Pitt, R. et al. "The Use of Special Inlet Devices, Filter Media, and Filler Fabrics for the Treatment of Storm
Waler." 9pp.
4. Eisenberg, Olivieri & Associates. 1996. Guidance for Monitoring the Effectiveness of Storm Water Treatment
Best Management Practices. Prepared for the Bay Area Storm Water management Agencies Association. 5-6:5-
7.
5. JMM. 1992 A Study of Nationwide Costs to Implement Municipal Storm Water Best Management Practices.
Prepared for the Water Resources Committee American Public Works Association Southern Califomia Chapter.
4-3:4-14.
6. Maine Department of Environmental Protection. Environmental management: A Guide for the Town Officials.
16, 27.
7. Denver regional Council of Government. Nonpoint Source Demonstration Project. 7:14.
8. Environmental Protection Agency, 1990. Urban Targeting and BMP Selection. 25:31.
9. Strecker, Eric W. 1993. Assessment of Storm Drain Sources of Contaminants to Santa Monica Bay. 21:28, 32.
10. Metropolitan Washington Council of Governments. 1992, A Current Assessment of Urban Best management
practices. 7:13, 23:29,55:69, 105:109,
11. Unocal, "More Down to Earth Talk from Unocal - Best Management Practices,"
12. The Fertilizer Institute, 1985, Symposium: "Plant Nutrients Use and the Environment,"
13. The Fertilizer Institute. 1988. Best Management Practices.
14. 1994. Report of the Technical Advisor}- Committee for Plant Nutrient Management. 17:18.
15. Virginia State Water Control Board Planning Bulletin 321, 1979. Best Management Practices Handbook:
Urban. 111-1:111-9,111-45:111-48,111-63:111-69,111-163:111-229,
16. California Department of Transportation Environmental Program. 1997. Statewide Storm Water Management
Plan. B-14:B-53,C-l:C-22.
17. Caltrans Compost Storm Waler Filters (CFSs), Bonita Canyon & North Hollywood Maintenance Yard, 1998.
Table 9-15.
18. Minton, Gary R. "Storm Water Treatment by Media Filter." Dec. 11-12, 1997.
19. Ventura Countywide Storm Water Quality Management Program. "Draft Land Development Guidelines."
20. Environmental Protection Agency, 1993, Guidance Specifying Management Measures for Sources of Nonpoint
Pollution in Coastal Waters.
21. Caltrans, Storm Waier Program. BMP Retrofit Pilot Studies, Technical Informalion. 1999.
22. Caltrans. Compost Storm Water Filters (CSFs), Bonita Canyon & North Hollywood Maintenance Yard
1997/1998 Wet Season, Post Sampling Summary Report. 1998.
23. Environmental Protection Agency. 1999. Infiltration Trench. EPA 832-F-99-019.
24. Flan, Daryl R. and Himal Solanki. "Removal Efficiencies of Stormwater Control Structures."
25. Environmental Protection Agency. 1999. Hydrodynamic Separators. EPA 832-F-99-017.
26. Environmental Protection Agency. 1999, Storm Water Wetlands. EPA 832-F-99-025.
27. Environmental Protection Agency. 1999. Wet Detention Ponds. EPA 832-F-99-048.
28. Environmental Protection Agency. 1999. Inflltration Drainflelds. EP.A 832-F-99-018,
29. Environmental Protection Agency, 1999, Vegetated Swales. EPA 832-F-99-006.
30. Environmental Protection Agency, 1999, Sand Filters. EPA 832-F-99-007,
31. Environmental Protection Agency, 1999, Water Quality Inlets. EPA 832-F-99-029.
32. Environmental Protection Agency, 1999, Modular Treatment Systems. EPA 832-F-99-044.
33. Environmental Protection Agency. 1999. Bioretention. EPA 832-F-99-0I2.
34. Stenstrom, Michael K. and Sim-Lin Lau. "Oil and Grease Removal by Fioaling Sorbents in a CDS Device."
University of California, Los Angeles, 1998.
35. Stormceptor Performance Testing Results, http://www.stormceptor.com/monitor.html
Westmount Shopping Centre and Conventry University Testing Results.
36. Caltrans, Highway Design Manual, Chapter 890 - Storm Water Management. Table 892,3.1999,
37. Allen, Vaikko P. Results from the Vortechs Stormwater Treatment System Monitoring Program at Del-Orme
Publishing Company, Yarmouth, Maine. 1998.
38. Environmental Protection Agency and American Society of Civil Engineers. National Stormwater Best
Management Practices (BMP) Database. Version 1.0, June 1999.
39. Lau, Sim-Lin and Michael K. Strenstrom. "Catch Basin Inserts to Reduce Pollution from Stormwater."
Comprehensive Stormwater and Aquatic Ecosystem Management Conference, Auckland, NZ, February 22-26,
1999.
40. Petro-Marine Co. Curb Inlet Drain Diaper Insert. Contact Ronald Isaacson. 28 Buckley Road, Marlboro, NJ
07746.
41. Best Management Technologies Brochure, Conlact Rod Butler. 23 Balwin Ave, Crockett, CA 94525.
42. Washington State Department of Transportation. Highwav Runoff Manual. February 1995.
43. Environmental Protection Agency, 1999, Employee Training. EPA 832-F-99-010,
44. Caltrans, El Toro Detention Basin Storm Water Monitoring 1997/1998 Wet Season, Post Sampling Summary
Repon. 1998,
Caltrans - Best Management Practices Pilot Studies
Removal Efficiency %
BMP Type Site
Localion
Approxinialc
Construdion
Cosi
Drainage
Area
(acres)
Design
Storm
(in.)
Design
Peak Flow
(ds)
Wet
Season
Number
of
Storms
TSS Nilralc Nilrilc Dissolved
Phosphorous
Tolal
Phosphorus
TKN Bcnel'icial
Uses
Los Angeles Area
Bio Strip
- are broad surfaces
wilh a full grass cover
that allows storm water
lo tlow in a relatively
thin sheets.
Alladcna
Maim
Slation
$218,000 1.7 1.0 1.2 N/A N/A N/A N/A N/A N/A N/A N/A RECl,
REC2
Infiltration Trench
-a Irench is a depression
used to treat small
drainage areas by
detaining siorm water
I'or short periods unlil it
percolates to lhe
proundwater table.
Alladcna
Maint
Station
(built w/ bio
slrip)
1.7 1.0 1.2 N/A N/A N/A N/A N/A N/A N/A N/A RECl,
REC2
Bio Slrip I-60.VSR9I $193,000 0.5 1.0 0,1 N/A N/A N/A N/A N/A N/A N/A N/A RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
Bio Swale
- arc vegelaled
conveyance channels
(typically trapezoidal
shaped) whecre storm
water How passes
Ihrough lhe grass at a
specific depth.
I-60.S/SR91 (buill w/ bio
strip)
0.2 1.0 0.1 N/A N/A N/A N/A N/A N/A N/A N/A RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
Bio Swale Cerritos
Maim
Sialion
$59,000 0.4 1.0 0,1 N/A N/A N/A N/A N/A N/A N/A N/A RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
Caltrans - Best Management Practices Pilot Studies
Removal Efficiency %
BMP Type Site
Localion
Approximate
Construction
Cost
Drainage
Area
(acres)
Design
Storm
(in.)
Design
Peak Flow
(ds)
Wel
Season
Number
of
Storms
TSS Nilralc Nilrite Dissolved
Phosphorous
Total
Phosphorus
TKN Beneficial
Uses
Bio Swale I-.5/1-605 $97,000 0.7 1.0 0.3 N/A N/A N/A N/A N/A N/A N/A N/A RARE.
RECl,
REC2.
SPWN,
WILD,
GWR
Bio Swale l-60.S/Dcl
Amo Ave
$ 124,000 0.7 1.0 0.2 N/A N/A N/A N/A N/A N/A N/A N/A RARE,
RECl,
REC2.
SPWN,
WILD,
GWR
Infillralion Basin
- a basin is a depression
used to treat larger
drainage areas by
detaining storm waler
lor shorl periods until il
pcrcolales lo lhe
groundwater lable.
I-605/SR9I $273,000 4,2 1.0 0.9 N/A N/A N/A N/A N/A N/A N/A N/A RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
Drain Inlel Insert
(stream guard)(a)
- sock type inseris lhal
allow collecled water to
filler Ihrough the
geotextile fabric.
Las Flores
Maint
Station
$88,000 0.2 1.0 O.l N/A N/A N/A N/A N/A N/A N/A N/A WILD
Drain Inlel Insert (fossil
niter)
- trough type inserts
filled wilh granular
amorphous alumina
silicate media.
Las Flores
Maint
Station
(buill w/DM
(a))
0.8 1.0 0.2 N/A N/A N/A N/A N/A N/A N/A N/A WILD
Drain Inlet Insert
(stream guard)(a)
Rosemead
Maim
Station
$65,000 0.3 1.0 0.1 N/A N/A N/A N/A N/A N/A N/A N/A WILD,
GWR,
RECl,
REC2,
WARM
Caltrans - Best Management Practices Pilot Studies
Removal Elficiency %
BMP Type Site
Localion
Approximate
Conslruetion
Cost
Drainage
Area
(acres)
Design
Slorm
(in.)
Design
Peak Flow
(d's)
Wet
Season
Number
of
Storms
TSS Nilrale Nitrite Dissolved
Phosphorous
Total
Phosphorus
TKN Beneficial
Uses
Drain Inlet Insert (fossil
filler)
Rosemead
Maint
Station
(built w/ DM
(a))
1,2 1.0 0.5 N/A N/A N/A N/A N/A N/A N/A N/A WILD,
GWR,
RECl,
REC2,
WARM
Drain Inlet Insert
(stream guard)(a)
Foothill
Maim
Slation
$68,000 0,2 1.0 0.0 N/A N/A N/A N/A N/A N/A N/A N/A WILD,
GWR,
MUN,
RECl.
REC2,
WARM
Drain Inlel Insert (fossil
filler)
Foothill
Maim
Slation
(built w/ DII
(a))
16 1.0 0.4 N/A N/A N/A N/A N/A N/A N/A N/A WILD.
GWR,
MUN,
RECl.
REC2,
WARM
Extended Detention
Basin^
- is a depression lined
wilh either vegetated
soils or concrele.
I-.VI-605
Interscclion
$142,000 6.8 1.0 5.3 1998-
1999
2 -89
to
-71
-84 to
23
N/A N/A -84 10
-81
-83
10
-92
RARE,
RECl,
REC2.
SPWN.
WILD,
GWR
Exicndcd DetciUion
Basin^
l-60,VSR9l
Intersection
$ 137,000 0.8 1.0 1.2 1998-
1999
?. -86
lo
-58
-54 U)
2
N/A N/A 15 lo
222
-8 lo
339
RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
Caltrans - Best Management Practices Pilot Studies
Removal Efficiency %
BMP Type Site
Localion
Approximate
Conslruclion
Cost
Drainage
Area
(acres)
Design
Slorm
(in.)
Design
Peak Flow
(d's)
Wet
Season
Number
of
Storms
TSS Nilrale Nilrile Dissolved
Phosphorous
Tolal
Phosphorus
TKN Beneficial
Uses
Media Filler^
- designed removes fine
sediment and particulate
pollutants through two
concrele lined vaults
(sedimentation vault
and fillcring vaull).
Three filter types 1)
Austin - open lopped, 2)
Delaware - closed
lopped, 3) canister -
uses pearlile/zeolite
media.
Eastern
Reg. Maint
Sla
$341,000 1.5 1.0 1.9 1998-
1999
1 -34 1 12 N/A N/A 10 108 WILD,
GWR,
REC2,
WARM
Media Filter* Foothill
Maim
Sialion
$479,000 1.8 1.0 3.0 1998-
1999
2 -42
10
-34
285 to
289
N/A N/A -7 to
83
42 to
140
WILD,
GWR,
MUN,
RECl,
REC2.
WARM
Media Filter Terminatio
n Park &
Ride
$450,000 2.8 1.0 3.6 N/A N/A N/A N/A N/A N/A N/A N/A RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
Media Filler Paxlon
Park &
Ride
.$331,000 1.3 1.0 1.7 N/A N/A N/A N/A N/A N/A N/A N/A GWR,
REC2
r
Caltrans - Best Management Practices Pilot Studies
BMP Type Siie
Location
Approximate
Construction
Cosi
Drainage
Area
(acres)
Design
Storm
(in.)
Design
Peak Flow
(el's)
Wel
Season
Number
of
Storms
Removal Efilciency %
TSS Nitrate Nitrite Dissolved
Phosphorous
Total
Phosphorus
TKN Beneficial
Uses
Multi-Chambered
Treatment Train
- Three chamber
mechanism I) catch
basin, which functions
primarily as a screening
process, 2) settling
chamber, which
removes settleable
solids with plate
separators and sorption
pads, 3) media filler,
which uses a
combination of sorption
(through layers of sand
and peat covered by
filler material) and ion
exchange.
Via Verde
Park&
Ride
$375,000 1.1 1.0 N/A N/A N/A N/A N/A N/A N/A N/A WILD,
WET,
GWR.
RECl,
REC2,
WARM
Multi-Chambered
Treatment Train
Metro
Maint
Station
$893,000 4,6 6.6 N/A N/A N/A N/A N/A N/A N/A N/A GWR,
RECl.
REC2,
WARM
Multi-Chambered
Treatment Train
Lakewood
Park &
Ride
$456,000 1.0 N/A N/A N/A N/A N/A N/A N/A N/A RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
Caltrans - Best Management Practices Pilot Studies
Removal Efficiency %
BMP Type Site
Location
Appioximale
Conslruetion
Cost
Drainage
Area
(acres)
Design
Slorm
(Ml.)
Design
Peak Flow
(ds)
Wet
Season
Number
ol'
Storms
TSS Nitrate Nilrite Dissolved
Phosphorous
Total
Phosphorus
TKN Beneficial
Uses
Continuous Deflection
Separator
- a pre cast underground
unil placed downstream
of freeway drain inlets
10 capture sediment and
debris. The unil creates
a vortex of water lhal
allows waler to escape
through screens, while
contaminants are
defiected inlo a sump,
and later removed.
l-2IO/Orcas
Ave
$62,000 I.l 1.0 0.3 N/A N/A N/A N/A N/A N/A N/A N/A WILD,
GWR.
RECl,
REC2,
WARM
Continuous Defiection
Separator
1-
210/Filmor
e Sl
$63,000 2.5 1.0 0.6 N/A N/A N/A N/A N/A N/A N/A N/A WILD,
GWR,
RECl.
REC2,
WARM
Media Filler (composl)'^ N.
Hollywood
Maint Sla
$40,000 3.0 0.7 1.0 1997-
1998
5 -155 7 29 38' 28" 43
2
Media Filler (compost) Boniia
Canyon
1.7 0,8 6.0 1997-
1998
5 72 -172 -233 -1633 -320 -133
Extended Detention
Basin "
El Toro 68 0,8 30.4 1997-
1998
5 88 15 61 22 57 40 RARE,
RECl,
REC2,
SPWN,
WILD,
GWR
San Diego Area
Caltrans - Best Management Practices Pilot Studies
Removal Efficiency ' k'
BMP Type Siie
Localion
Approximate
Construction
Cost
Drainage
Area
(acres)
Design
Storm
(in.)
Design
Peak Flow
(d's)
Wet
Season
Number
of
Storms
TSS Nitrate Nilrilc Dissolved
Phosphorous
Total
Phosphorus
TKN Beneficial
Uses
Extended Detention
Basin
1-
5/Manchcsl
er (east)
$369,000 4.8 1.3 4.6 N/A N/A N/A N/A N/A N/A N/A N/A RECl,
REC2,
BIOL
EST,
WILD,
RARE,
MAR,
MIGR
Extended Detention
Basin
I-.VSR.S6 $166,000 5.3 1.3 5.7 1998-
1999
5 23
to
80
-100
to 64
-65 to
68
-84
to 43
BIOL
EST,
MAR.
MIGR,
RARE,
RECl,
REC2,
SHELL
WILD
Extended Detention
Basin
I-I.5/SR78 $855,000 13,4 1.9 9.5 1998-
1999
4 45
to
72
-240
10 58
-299 to -62 -IOI
to 19
AGR,
COLD,
MUN,
RECl.
REC2,
WARM,
WILD
Infillralion Basin l-5/La
Cosla
(west)
.$241,000 3.2 1.3 3.0 N/A N/A N/A N/A N/A N/A N/A N/A BIOL,
EST,
MAR.
MIGR,
RARE.
RECl,
REC2,
WARM
Caltrans - Best Management Practices Pilot Studies
Removal Efficiency %
BMP Type Site
Location
Approximate
Conslruclion
Cost
Drainage
Area
(acres)
Design
Slorm
(in.)
Design
Peak Flow
(d's)
Wci
Season
Number
of
Siorms
TSS Nilrale Nilrile Dissolved
Phosphorous
Total
Phosphorus
TKN Beneficial
Uses
Wet Basin
- a basin consisting of a
permanent pool of water
surrounded by a variety
of wetland plant
species.
l-5/La
Costa (casi)
$694,000 4.2 1.3 2.2 N/A N/A N/A N/A N/A N/A N/A N/A RECl,
REC2,
BIOL,
EST,
WILD,
RARE,
MAR,
MIGR
Media Filler
(pearolile/zcolile)
Kearny
Mesa Maint
Sla
$340,000 1.5 09 2.7 1998-
1999
3 -27
10
20
5 U)
29
-115 10 46 5 lo
32
REC2,
WARM,
WILD
Media Filler (sand lype
II)
Escondido
Mainl
Sialion
$451.000 0.8 1.0 2.2 1998-
1999
3 0 lo
66
1 1 10
70
-23 to 70 56 10
84
MUN,
AGR,
RECl,
REC2.
WARM
COLD.
WILD
Media Filler (sand type
1)
La Cosla
Park &
Ride
$242,000 2.8 0.9 2.3 1998-
1999
3 54
lo
98
-98 to
4
-113 to 26 -28
to 38
BIOL
EST,
AMR,
MIGR,
RARE,
RECl,
REC2,
WARM
Media Filler (sand type
1)
SR78/I-5
Park &
Ride
$231,000 0.8 1.0 2.7 1998-
1999
2 54 -313 -7 10 28 7 10
11
BIOL.
MAR,
RARE.
RECl,
REC2.
WARM.
WILD
Bio Swale SR78/Melr
osc Dr
$156,000 2.4 1.2 6.1 N/A N/A N/A N/A N/A N/A N/A N/A AGR,
OMD,
RECl,
REC2,
WARM,
WILD
Caltrans - Best Management Practices Pilot Studies
Removal Efficiency %
BMP Type Site
Location
Approximate
Construction
Cost
Drainage
Area
(acres)
Design
Storm
(in.)
Design
Peak Flow
(d's)
Wcl
Season
Number
of
Siorms
TSS Nitrate Nilrite Dissolved
Phosphorous
Total
Phosphorus
TKN Beneficial
Uses
Bio Swale l-.5/Palomar
Airport Rd
$142,000 2.3 N/A 3.8 N/A N/A N/A N/A N/A N/A N/A N/A REC2,
WARM,
WILD
Bio Slrip Carlsbad
Maim Sla
(west)
$196,000 0.7 N/A 1.3 N/A N/A N/A N/A N/A N/A N/A N/A REC2.
WARM,
WILD
Infillralion Trench/Strip Carlsbad
Mainl Sla
(east)
(built w/ bio
slrip)
1.7 1.3 2.9 N/A N/A N/A N/A N/A N/A N/A N/A REC2,
WARM,
WILD
Caltrans. BMP Retrofit Pilot Studies: Technical Information. 1999. This information is preliminary and will be verifled later.
' Caltrans. Compost Storm Water FUters (CSFs), Bonita Canyon li North Hollywood Maintenance Yard, Storm Water Monitoring. 1998.^ Caltrans. El Toro Detention Basin.
Storm Water Monitoring. 1998.
Dissolved Phosphorus higher than Tolal Phosphorus concentrations, due lo results from slorm 4. Without slorm 4, efflciencies are -36% for dis.solved phosphorus and 7% for
total phosphorus.
N/A - Not Available al this time. • Preliminary Information.
APPENDIX 3
TABLE 6: GRASS LINED BIOFILTER BMP DISCHARGE
AND
TREATMENT AREA
TABLE 6
GRASS LINED BIOFILTER BMP DISCHARGE AND TREATMENT AREA
Treatment Discfiarge
Location PA Area: A Runoff Intensity: l'^' Treatment Grass Swale Grass Swale
Coefficient: C Discharge Q Treatment Area Length
(ac) (In / hr) (cfs) (sqft) (ft)
PAI 2.3 0.95 0.2 0.4 1840 37
PA2 21.9 0.95 0.2 4.2 17520 350
PA3a 25.5 0.95 0.2 4.8 20400 408
PA3b 21.0 0.95 0.2 4.0 16800 336
PA4 39.0 0.95 0.2 7.4 31200 624
PAS 31.0 0.95 0.2 5.9 24800 496
Notes:
(1) Intensity, I = BMP design rainfall intensity per State Water Quality Control Board Order Num
(2) Treatment Discharge Q = CIA.
(3) Grass Swale Treatment Area assumes a minimum treatment area of 1000 sq-ft per impervious acre. The
industrial sites are assumed to be 80% impervious.
(4) Grass Swale length assumes a 50 foot wide swale.
APPENDIX 4
TABLE 7: INDIVIDUAL PLANNING AREA
WET POND/RETENTION BASIN TREATMENT VOLUMES
AND
BASIN GEOMETRIES
Table 7
Bressi Ranch
Basin Treatment Volumes
Treatment Volume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-1 2.3 100188 0.60 0.05 5009
Basin Width or Lenqtli
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenqth
(ft)
2
3
4
5
50
33
25
20
33
22
17
13
25
17
13
10
17
11
8
7
13
8
6
5
Treatment Volume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-2 22 953964 0.60 0.05 47698
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth Calculated Basin Width or Lenqth
(ft) (ft)
2 477 318 238 159 119
3 318 212 159 106 79
4 238 159 119 79 60
5 191 127 95 64 48
Table 7
Bressi Ranch
Basin Treatment Volumes
Treatment Vo ume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-3a 25.5 1110780 0.60 0.05 55539
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenath
(ft)
2
3
4
5
555
370
278
222
370
247
185
148
278
185
139
111
185
123
93
74
139
93
69
56
Treatment Volume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-3b 21 914760 0.60 0.05 45738
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenath
(ft)
2
3
4
5
457
305
229
183
305
203
152
122
229
152
114
91
152
102
76
61
114
76
57
46
Table 7
Bressi Ranch
Basin Treatment Volumes
Treatment Vo ume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-4 39 1698840 0.60 0.05 84942
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenath
(ft)
2
3
4
5
849
566
425
340
566
378
283
227
425
283
212
170
283
189
142
113
212
142
106
85
Treatment Volume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-5 31 1350360 0.60 0.05 67518
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenath
(ft)
2
3
4
5
675
450
338
270
450
300
225
180
338
225
169
135
225
150
113
90
169
113
84
68
APPENDIX 5
TABLE 8: COMBINED PLANNING AREA
WET POND/RETENTION BASIN TREATMENT VOLUMES
AND
BASIN GEOMETRIES
Table 8
Bressi Ranch
Basin Treatment Volumes
Treatment Volume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-1-PA-5 140.7 6128892 0.60 0.05 306445
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenqth
(ft)
2
3
4
5
3064
2043
1532
1226
2043
1362
1021
817
1532
1021
766
613
1021
681
511
409
766
511
383
306
Treatment Vo ume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-3a-PA-5 116.5 5074740 0.60 0.05 253737
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenqth
(ft)
2
3
4
5
2537
1692
1269
1015
1692
1128
846
677
1269
846
634
507
846
564
423
338
634
423
317
254
Table 8
Bressi Ranch
Basin Treatment Volumes
Treatment Volume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA-3a+3b 46.5 2025540.0 0.6 0.05 101277
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth
(ft)
Calculated Basin Width or Lenqth
(ft)
2
3
4
5
1013
675
506
405
675
450
338
270
506
338
253
203
338
225
169
135
253
169
127
101
Treatment Volume
Location PA area
(acres)
PA area
(ft)
Treatment
Precipitation
(in)
Treatment
Precipitation
(ft)
Treatment
Volume
(cuft)
PA.4-I-PA-5 70 3049200 0.60 0.05 152460
Basin Width or Lenqth
(ft)
50 75 100 150 200
Basin Depth Calculated Basin Width or Lenath
(ft) (ft)
2 1525 1016 762 508 381
3 1016 678 508 339 254
4 762 508 381 254 191
5 610 407 305 203 152
APPENDIX 6
INDUSTRIAL STORM WATER SOURCE CONTROL BMPS
4. SOURCE CONTROL BMPs
This chapter
INTRODUCTION describes specific
., ~ ' source control
mmm^^^mammmmmimmmm^ BcSt
Management
Practices (BMPs) for common industrial
activities that may pollute storm water. Chapter
2 led you through the steps of identifying
activities at your facility that can pollute storai
water while Chapter 3 provided guidance on
selection of BMPs. This ciiapter provides you
with the BMPs that best fill your facility's need.
Best management practices for each of the
activities shown below are provided in the
following fact sheets.
Each fact sheet contains a cover sheet with:
• A description of the BMP
• Approach
• Requirements
- Cost, including capital costs, and
Operation and Maintenance (O&M)
- Maintenance (including administrative and
staffing)
• Limitations
The side bar presents infonnation on where Uiis
BMP applies, targeted constituents, and an
indication of Uie level of effort and cost to
implement
Further infonnation is also provided in
additional sheets. This information includes a
more detailed description of Uie BMP,
requirements to implement, examples of
effective programs, and references.
BMPs are provided for each of Uie following
industrial activities consistent wiUi Worksheet 4
in Chapter 2.
Industrial Activities Requiring BMPs
SCI Non-Storm Water Discharges to
Drains
SC2 Vehicle and Equipment Fueling
SC3 Vehicle and Equipment Washing and
Steam Cleaning
SC4 Vehicle and Equipment Maintenance
and Repair
SCS Outdoor Loading/Unloading of
Materials
SC6 Outdoor Container Storage of Liquids
SC7 Outdoor Process Equipment
Opeiations and Maintenance
SC8 Outdoor Storage of Raw Materials,
Pnxlucts, and By-Products
SC9 Waste Handling and Disposal
SClO Contaminated or Erodible Surface
Areas
sen Building and Grounds Maintenance
SC12 Building Repair, Remodeling, and
Construction
SC13 Over-Water Activities
SCM Employee Training
Fact sheet SCM, Employee Training, is a
compilation of Uie training aspects of Uie
individual source control fact sheets. Its
purpose is to facilitate Uie integration and
development of a comprehensive training
program for all industiial activities at a facility.
Industrial Handbook 4.1 March, 1993
ACTIVITY: NON-STORM WATER DISCHARGES TO DRAINS Applications
<^^^^~Manufacturirtg~^^
Materiai Handling
<C^Vehicle Maintenan^^
Construction
C^Qomrnercial Activit^^
Roattways
Waste Containmerrt
housekeeping Practices^
DESCRIPTION
Eliminate non-stonn water discharges to the storm water coUectioa system. Noo-storm
water discharges may include: process wastewaters, cooling wateis, wash waters, and
sanitaiy wastewater.
APPROACH
Tbe following approaches may be used to identify non-storm water discharges:
• Visual Inspection
Tbe easiest method is to inspect each discharge point during dry weather.
Keep in mind that diainage from a storm event can continue for three days or
more and groundwater may infiltrate the underground storm water collection
system.
• Piping Schematic Review
Tbe piping schematic is a map of pipes and drainage systems used to cany
wastewater, cooling water, sanitary wastes, etc.
A review of the "as-built" piping schematic is a way to determine if there are any
connections to the stonn water collection system.
Inspect the path of floor drains in older buildings.
• Smdce Testing
Smoke testing of wastewater and storm water coUection systems is used to detca
connections between the two systems.
During diy weather the stonn water collection system is filled with smoke and
then traced to sources. Tbe appearance of smoke at the base ofa toilet indicates
that there may be a connection between the sanitaiy and the stoim water system.
• Dye Testing
A dye test can be peifonned by simply releasing a dye into eiUier yonr sanitary
or process wastewater system and examining tbe discharge points from the stotm
water coUecticm system for discoloradon.
REQUIREMENTS
Costs (Capital, O&M)
• Can be difficult to locate illicit connections especially if there is groundwater
infiltration.
LIMITATIONS
• Many £acUities do not bave accurate, up-to-date schematic drawings.
• TV and visual inspections can identify illicit connections to die storm sewer, but
fiirtbcr testing is sometimes required (e.g. dye, smoke) to identify sources.
Targeted Constituents
O Sediment
# Nutrients
# Heavy Metals
9 Toxic Matariais
O Floatable Materials
9 Oxygen Demand-
ing Substances
0 Oil St Grease
0 Bacteria & Viruses
W UMytoHsve
Significant Impact
O Proltabla Low or
Unknown Impact
Implementation
Requiraments
O Capital Costs
O O&M Casts
O Maintenance
O Training
High O Low
SC1
Best^
Management
Practlces>
Industrial Handbook 4-2 March, 1993
Additional Information — Non-Storm Water Discharges to Drains
Facilities subject to storm water permit requirements must include a certification diat tbe storm water collecaon system
has been tested or evaluated for thc presence of non-stonn water discharges. Thc State's General Industrial Sttinn Water
Permit requires tbat non-storm water discbarges be eliminated prior to implementation of the facility's SWPPP.
Non-stonn water discbarges to die storm water coUection system may include any water used direcdy in tbe manufaaur-
ing process (process wastewater), air conditioning condensate and coolant, non-contaa cooling water, cooling equipment
condensate, outdoor secondary containment water, vehicle and equ^nnent wash water, sink and drinkmg fountain
wastewater, sanitary wastes, or other wastewaters. Table 4.1 presents disposal option information for specific types of
wastewaters.
To ensure that tbe storm water system discbarge contains only storm water, industry sboul±
• Locate discbarges to die municipal storm sewer system or waters of the United States from the mdustrial
stonn sewer system firom:
"as-built" pipeline schematics, and
visual observation (walk boundary of plant site).
• Locate and evaluate all discbarges to the indnstrial storm sewer system (including wel weather flows) from:
"as-built" pipeline schematics,
visual observation,
dye tests,
TV camera.
chemical field test kits, and
smoke tests.
• Devek>p plan to eliminate illicit connections:
repl umb sewer lines,
isolate problem areas, and
plug illicit disdiarge points.
• Devetop (fisposal options.
• Document tbat non-stonn water discharges have been eUminated by reconling tests performed, metiiods used, dates of testing, and any on-site drainage points observed.
REFERENCES
General Industrial Stoim Water Pennit, SWRCB, 1992.
NPDES General Pennit for Discbarges of Stonn Water Associated witii Industrial Activity in Santa Clara County
to South San Francisco Bay or its Tributaries, SFBRWQCB, 1992.
Stonn Water Management for Industrial Activities: Developing PoUution Prevention Plans, and Best Manaee-
mcnt Practices. EPA 832-R-92-006, USEPA, 1992..
Industrial Handbook 4-3 March, 1993
5*
a.
TABLE 4.1 QUICK REFERENCE - DISPOSAL ALTERNATIVES
(Adopted from Santa Clara County Nonpoint Source Pollution Conti-ol Program - December 1992)
All of Uic waste products on Uiis chart arc prohibited from discharge to die slorm drain system. Use Uiis matrix to decide which alternative disposal su-aiegics to use.
ALTERNATIVES ARE LISTED IN PRIORITY ORDER.
a Key: HHW Household hazardous waste (Government-sponsored drop-off events)
I POTW Publically Owned TreaUncnl Plant
I" Reg.Bd. Regional Water Quality Conti-ol Board (Oakland)
T "Dispose to sanitary sewer" means dispose into sink, toilet, or sanitary sewer clean-out connection.
"Dispose as trash" means dispose in dumpsters or Irash containers for pickup and/or eventual disposal in landfill.
"Dispose as hazardous waste" for business/commercial means conti'act wiUi a hazardous waste hauler to remove and dispose.
DISCHARGE/ACTIVITY BUSINESS/COMMERCIAL
Disposal Priorities Approval
RESIDENTIAL
Disposal Priorities
General Construction and Painting; Street and Utility Maintenance
Excess paint (oil-based) 1. Recycle/reuse.
2. Dispose as hazardous waste.
1. Recycle/reuse.
2. Take to HHW drop-off.
Excess paint (water-based) 1. Recycle/reuse.
2. Dry residue in cans, dispose ns trash.
3. If volume is loo much to dry,
dispose as hazardous waste.
1. Recycle/reuse.
2. Dry residue in cans, dispose as trash.
3. If volume is loo much to dry, lake to
HHW drop-off
Paint cleanup (oil-based) Wipe paint oul of brushes, Uien:
1. Filter & reuse iliinners, solvents.
2. Dispose as hnznrdous waste.
Wipe paint out of brushes, Uien:
1. Filter & reuse tliinners, solvents.
2. Take to HHW drop-off.
Point cleanup (water-based) Wipe paint oul of brushes, Uien:
1. Rinse to Siuiitary sewer.
Wipe paint oul of brushes, then:
1. Rinse to Siuiilary sewer.
Empty paint cans (dry) 1. Remove lids, dispose as Hash. 1. Remove lids, dispose ns uasli.
Paint su-ipping (wtUi solvent) 1. Dispose as hazardous waste. I. Take lo HHW drop-olf.
Building exterior cleaning (high-
pressure waler)
1. Prevent enlry into storm drain and
remove offsiie
2. Wash onto dirt area, spade in
3. Collect (e.g. mop up) and
discharge to sanitary sewer POTW
Cleaning of building exteriors which
have HAZARDOUS MATERIALS (e.g.
mercury, lead) in paints
1. Use dry cleaning methods
2. Contain nnd dispose wnshwnter as
hazardous waste (Suggestion: dry
material first to reduce volume)
2
n
NO t>J
Table 4.1 (Continued)
Page 2
5*
•1
s a
DISCHARGE/ACTIVITY BUSINESS/COMMERCIAL
Disposal Priorities Approval
RESIDENTIAL
Disposal Priorities
General Construction and Painting; Street and Utility Maintenance (cont'd)
Non-hazardous paint saaping/
sand blasting
1. Dry sweep, dispose as u-ash 1, Dry sweep, dispose as uash
HAZARDOUS paint scraping/sand blasting
(e.g. marine paints or paints containing
lead or uibuiyl tin)
1. Dry sweep, dispose as
hazardous waste
1. Dry sweep, Like lo HHW drop-off
Soil from excavations during periods
when storms are forecast 1. Should not be placed in sueet or
on paved areas
2. Remove from site or backfill by
end of day
3. Cover willi tarpaulin or surround
wiUi hny bales, or use oUier
runoff controls
4. Place filler mal over slorm drain
Note: Thoroughly sweep following removal of
din in all four ahematives.
-
Soil from excavations placed on paved
surfaces during periods when storms are not
forecast
1. Keep material out of storm conveyance
systems and Uioroughly remove via
sweeping following removal of dirt
Cleaning streels in caistruction areas 1. Dry sweep and ininimize tracking of
inud
2. Use sill ponds and/or similar polluiaiil
reduction techniques when Uusliing
pavement
Soil erosion, sediments 1. Cover disturbed soils, use erosion
coiiu-ols, block enuy to storm drain.
2. Seed or plant iininedialely.
Fresh cement, groul, mortar 1. Use/reuse excess
2. Dispose to irash
1. Use/reuse excess
2. Dispose as Uash
Washwater from concrele/mortar
(etc.) cleanup 1. Wash onto dirt area, spade in
2. Pump and remove lo appropriaie
disposal facility
3. Settle, pump water to sanitary sewer POTW
1. Wash onto dirt area, spade in
2. Pump and remove to appropriate
disposal facility
3. Settle, pump water to sanitary sewer
Aggregale wash from driveway/patio construction 1. Wash onto dirt area, spade in
2. Pump and remove to appropriate
disposjil faciiily
3. Sctllc, pump water lo sanitary sewer POTW
1. Wash onto dirt area, spade in
2. Pump and remove lo appropriate
disp()^>al facility
3. Sctllc, pump wilier lo sanitary scwcr
2
ta
<0
Table 4.1 (Continued)
Page 3
5*
a
a a.
r
DISCHARGE/ACTIVITY BUSINESS/COMMERCIAL
Disposal Priorities Approval
RESIDENTIAL
Disposal Priorities
General Construction and Painting; Street and Utility Maintenance (cont'd)
Rinsewater from concrete mixing micks 1. Return mick to yard for rinsing
into pond or dirt area
2. Al construction site, wash into pond
or dirt nrcn
Non-hazardous construction and
demolilion debris
1. Recycle/reuse (concrele, wood, etc.)
2. Dispose as UTish
1. Recycle/reuse (concrele, wood, etc.
2. Dispose ns Uash
Hazardous demolition and
consuuction debris (e.g. asbestos)
1. Dispose as hazardous waste 1. Do nol attempt to remove yourself.
(^onUict asbestos removal service for
safe removal and disposal
2. Very small amounts (less Uian 3 Ibs)
may be double-wrapped in plastic and
liiken to HHW drop-off
Saw-cut slurry 1. Use dry culling technique and sweep
up residue
2. Vacuum slurry and dispose off-site.
3. Block stonn drain or berm wiUi low
weir as necessary to allow most solids
to settle. Shovel out gutters; dispose
residue lo dirt area, consu-uciion yard
or landfill.
Consuuction dewatering
(Nonlurbid, unconinminnied groundwaier)
1. Recycle/Reuse
2. Discluu-ge lo stonn drain
Consuuction dewatering (OUier tlian
nonlurbid, unconlaminated groundwater)
1. Recycle/reuse
2. Discharge to sanitary sewer
3. As appropriate, ueat prior to
discharge to stonn drain
POTW
Reg. Bd.
Portable toilet waste 1. Leasing company shall dispose
10 saniuuy sewer at POTW POTW
Leaks from garbage dumpsters 1. Collect, contain leaking material.
Eliminate leak, keep covered,
return to leasing company for
immediate repair
2. If dumpster is used for liquid
waste, use plastic liner
4^
VO
Table 4.1 (Continued)
Page 4
5'
I -I
a a
r
DISCHARGE/ACTIVITY BUSINESS/COMMERCIAL
Disposal Priorities Approval
RESIDENTIAL
Disposal Priorities
General Construction and Painting; Street and Utility Maintenance (cont'd)
Leaks from consuuction debris bins 1. Insure that bins are used for dry
nonhazardous malerials only
(Suggestion: Fencing, covering help
prevent misuse)
Dumpster cleaning waier 1. Clean at dumpster owner's faciiily
and discharge waste Uirough grease
iiilerceplor lo sanitary sewer
2. Clean on site and discharge Uirough
grease interceptor lo sanitary sewer
POTW
POTW
Cleaning driveways, paved areas *
(Special Focus = Rcsmurant alleys Grocery
dumpster areas)
* Note: Local drought ordinances may
conuiiii addiiionnl resuiciions
1. Sweep and dispose as tnish
(Dry cleaning only).
2. For vehicle leaks, restauroni/grocery
alleys, follow Uiis 3-siep process:
a. Clean up leaks wiUi rags or
absorbents.
b. Sweep, using granular
absorbent malerial (cal litter).
c. Mop and dispose of mopwaier to
sanitary sewer (or collect rinsewater
and pump lo Uie sanitary sewer).
3. Siune as 2 above, but wiUi rinsewater
(2c)(no saip) discharged to stonn drain.
1. Sweep and dispose as Uash (Dry denning
only).
2. For vehicle leaks, follow ihis
3-sicp process:
a. Clean up leaks widi rags or
absorbents; dispose ns hazardous
waste.
b. Sweep, using granular
absorbent material (cal litter).
c. Mop and dispose of mopwaier
lo sanitary sewer.
Steam clean ing of sidewalks, plazas *
* Note: Local drought ordinances may
contain addilionai resuictions
1. Collect all waler and pump to sanitary
sewer.
2. Follow Uiis 3-siep process:
a. Clean oil leaks wiUi rags or
adsorbents
b. Sweep (Use dry absorbent as needed)
c. Use no soap, discharge to stonn drain
Potable water/line flushing
Hydrant testing
1. Deactivate chlorine by
maximizing time water will uavel
before reaching creeks
Super-chlorinated (above 1 ppm) waler
from line Hushing
1. Discharge to saniUuy sewer
2. Complete dechlorination required
before discharge lo sionn drain
I
1 O er
NO
VO
Table 4.1 (Continued)
Page 5
DISCHARGE/ACTIVITY BUSINESS/COMMERCIAL
Disposal Priorities Approval
RESIDENTIAL
Disposal Priorities
Landscane/Garden Maintenance
Pesticides 1. Use up. Rinse conuiiners use
rinsewater as product Dispose
rinsed conuiiners as uash
2. Dispose unused pcsUcide as
liazardous waste
1. Use up. Rinse conuiiners, use
rinsewater as pesticide. Dispose
rinsed container as Uash.
2. Take unused pesUcide lo HHW drop-
off
Garden clippings 1. Compost
2. Take to Landfill
1. Compost
2. Dispose as Inisli.
Tree uimining 1. Chip if necessary, before
composting or recycling
1. Chip if necessary, before composting
or recycling
Swiimning pool, spa, fountain water
(emptying)
1. Do not use meuil-based algicides (i.e.
Copper Sulfate)
2. Recycle/reuse (e.g. irrigaiion)
3. Detennine chlorine residual = 0, wail
24 hours and Uien discharge lo stonn drain. POTW
1. Do nol use meUil-bnscd algicides (i.e.
Copper Sulfate)
2. Recycle/reuse (e.g. irrigation)
3. Detennine chlorine residual = 0, wait
24 hours and then discharge to stonn drain.
Acid or oUier pool/spa/fountain cleaning 1. Neuualize and discharge to sanitary
sewer POTW
Swiimning pool, spa filler backwash 1. Reuse for irrignUon
2. Dispose on dirt nren
3. Scale, dispose to snnilary sewer
1. Use for Imidsciipe irrigaUoii
2. Dispose on dirt area
3. Settle, dispose to sanitary sewer
Vehicle Wastes
Used motor oil 1. Use secondary conmiiunenl while
sioring, send lo recycler.
1. Put oul for curbside recycling pickup
where available
2. Take to Recycling Facility or aulo
service facility wiUi recycling program
3. Take lo HHW events accepting motor oil
AnUfrecze I. Use secondary containment while
storing, send lo recycler.
1, Take to Recycling Faciiily
Oilier vehicle fluids and solvents 1. Dispose as hazardous waste 1. Take to HHW event
Automobile batteries 1. Send to aulo ballery recycler
2, Take lo Recycling Cenler
1. Exchiuige nl reuiil ouUel
2. Take lo Recycling Faciiily or HHW event
wliere batteries are accepted
Motor homc/consuuction Uai ler waste 1. Use holding uuik. Dispose to
sanitary sewer
1. Use holding tank, dispose lo sanitary
sewer.
Table 4.1 (Continued)
Page 6
5* a.
1
E5-
a
DISCHARGE/ACTIVITY DUSINESS/COMMERCIAL RESIDENTIAL
Disposal Priorities Approval Disposal Priorities
Vehlcie Wastes (cont'd)
Vehicle Washing 1. Recycle
2. Discharge to saniuuy
sewer, never to stonn drain
POTW
1. Take lo Commercial Car Wash.
2. Wash over lawn or dirt area
3. If sonp is used, use a bucket for sonpy
waler and discharge remaining sonpy
water to saniuuy sewer.
Mobile Vehicle Washing 1. Colled washwater and discharge lo
saniuiry sewer. POTW
Rinsewater from dust removal at new car
fleets
1. Discharge to saniuuy sewer
2. If rinsing dust from exterior surfaces
from appearance purposes, use no soap
(water only); discharge lo sionn drain. POTW
-
Vehicle leaks at Vehicle Repair FaciiiUes Follow this 3-siep process:
1. Clean up leaks wiUi rags or absorbents
2. Sweep, using granular absorbent
material (cat litter)
3. Mop nnd dispose of mopwaier lo
sanibu-y sewer.
Other Wastes
Carpel cleaning solutions & oUier
mobile washing services
1. Dispose lo snnilnry sewer POTW 1. Dispose 10 saniuuy scwcr
Roof drains 1. If roof is conliuniiiated wiUi
indusuial wasie products,
discharge lo saniuuy sewer
2. If no contamination is present,
discharge to stonn drain
Cooling water
Air condiUoning condensate
1. Recycle/reuse
2. Discharge lo saniuuy sewer POTW
Pumped groundwater, infiluatioii/
foundation dnunage (containinnied)
1. Recycle/reuse (Inndscaping, etc.)
2. Treat if necessary; discharge lo
snniuiry sewer
3. Treat and discharge to stonn drain
Reg. Bd.
POTW
Reg. Bd.
Fire tigliting flows If coiiuiininalion Is present, Fire Dept.
will nllempl to prevent flow lo sueam
or stonn drnin
2
vo v«
Table 4.1 (Continued)
Page 7
5* a
t E m
9
a
r
DISCHARGE/ACTIVITY BUSINESS/COMMERCIAL
Disposal Priorities Approval
RESIDENTIAL
Disposal Priorities
Other Wastes (cont'd)
Kitchen Grease 1. Provide secondary conminment, collect,
send to rccyler.
2, Provide secondary containment, collect,
send 10 POTW via hauler.
POTW
1. Collect, solidify, dispose as Uash
Resuiurant cleaning of floor mats,
exhaust fillers, etc.
1. Clean inside building wiUi dischnrge
Uirough grense unp lo snnilnry sewer.
2. Clean outside in conlainer or benned
area with discharge to sanitary sewer.
Clean-up wastewater from sewer back-up 1. Follow Uiis procedure:
a. Block stonn drain, conuiin, collect,
nnd return spilled material to the
saniliuy sewer.
b. Block Slorm drain, rinse remaining
malerial lo collection point and
pump to saniuuy sewer, (no rinse-
water may flow lo stonn drain)
t)
n sr
vo VO
ACTIVITY: VEHICLE AND EQUIPMENT FUELING Applications
Manufacturing
^Material Handling^
"Vehicle Maintenance
Construction
(Commercial Activities^
Roadways
Waste Containment
(housekeeping Practi^s^
DESCRIPTION
Prevent fuel spiUs and leaks, and reduce their impacts to storm water.
APPROACH .
• Design the fueling area to prevent tbe runon of stotm water and tbe runoff of spUls:
Cover fueling area if possible.
Use a perimeter drain or slope pavement inward with drainage to sump.
Pave fueling area with concrete rather Uian aspbalL
• Where covering is infeasible and die fuel island is suirounded by pavement, apply a
suitable sealant tbat protects tbe asphalt from spiUed fuels.
If dead-end sump is not used to coUect spiUs, instaU an oU/water separator.
• InstaU vapor recovery nozzles to help control drips as well as air poUution.
• Discourage "topping-ofr of fuel tanks.
• Use secondary containment wben oansfeiring fuel from the tank truck to tbe fuel
tank.
• Use adsoibent inaterials on smaU spUIs and general cleaning rather Uian hosing down
Uie area. Remove tbe adsortjent materiais promptiy.
• Carry out aU Federal and State requirements regarding underground sUHage tanks, or
instaU above ground tanks.
• Do not use mobUe fueling of mobile industiial equipment around tbe facility; rather,
transport the equipment to designated fueling areas.
• Keep your SpiU Prevention Control and Countermeasure (SPCQ Plan up-to-date.
• Train employees in proper fueling and cleanup procedures.
• For a quick reference on disposal alternatives for specific wastes see Table 4.1, SCI.
REQUIREMENTS
• Costs (Capital, O&M)
The retrofitting of existing fiieling areas to mininuze storm water exposure or
spill runoff can be expensive. Good design must occur during Uie initial instaUa-
tion. Extruded curb along the "upstream" side of Uie fueling area u> prevent
storm water runon is of modest cost
• Maintenance
Oeaa oil/water separators at Uie appropriate intervals.
Keep ample supplies of spUl cleanup materials on-site.
Inspect fueling areas and stooge tanks on a regubr schedule.
LIMITATIONS
• Oil/water separators are only as effective as Uieir maintenance program.
Targeted Constituents
O Sediment
O Nutrients
# Heavy Metals
0 Toxic Materials
O Floatable Materials
O Oxygen Demand-
ing Substances
# Oil & Grease
O Bacteria & Viruses
Significant Impact
O Probable Low or
Unknown Impact
Implementation
Requirements
O Capital Costs
O OiM Costs
O Maintenance
O Training
High O Low
SC2
Best'
Management^
PracticesN
Industrial Handbook 4 - 11 March, 1993
Additionai Information — Vehicle and Equipment Fueling
Spills from fueling or from Uic uansfer of fuels to Uie storage tank can be a significant source of poUution. Fuels carry
contaminants of particular concem to humans and wUdlife, such as heavy metals, toxic materials, and oil and grease,
which are not easUy removed by storm water treatment devices. Consequentiy, contiol at tbe source is particularly
importanu Adequate control can be achieved with careful design of tbe initial installation, retrofitting of existing
instaUations, and propcx spiU control and cleanup procedures, as described below.
Desiyn
Witb new installations, design Uie fueling area to prevent tbe runon of stotm water and the runoff of spills. This can be
achieved by contouring Uie site in tbe appropriate fashion. Covering Uie site is Uie best approach but may not be feasible
if very large mobile equipment is being fueled. Storm water runon can be diverted around Uie fueling area by an extruded
curt) or wiUi a "speed bump", if vehicle access is needed from Uiis direction. SpUls can be contained wiUiin thc fiieling
area eiUier by using a perimeter drain or by sloping tlie pavement inward wiUi drainage to a sump. In both cases die
drain can be connected to tbe storm drain witb a valve Uiat is only closed during fueling opeiations and left open at aU
oUier times. Pave the fueling area wiUi Portland cement concrete raUier than asphalt, since tbe latter wUl gradually
disintegrate and be washed tmm tbe site.
SpiU Confrol
The foUowing spill control measures wUl reduce spilling or reduce Uie loss of spiUed fuels from Uie site:
• InstaU vapor recoveiy nozzles.
Do not "top off tanks.
• Place secondaiy containment around the fuel tiuck when it is tiansferring fuel to the storage tank. The truck
operator should remain with tbe truck whUe the transfer is in progress.
Place a stockpile of spUl deanup materials where il wUl be readily accessible.
• Use diy metbods to clean tbe fueling area whenever possible. If you periodicaUy clean by pressure washing, place a
temporaiy plug in tbe downstream drain and pump out tbe accumulated water. Property dispose the water.
• Train employees on proper fueling and deanup procedures.
Dcsipnarcrt Arrgi
If your facility has large numbers of mobile equipmenl woiking throughout die site and you currendy fuel Uiem wiUi a
mobile fud tiuck, consider establishing a designated area for fueUng. WiUi tbe exception of tracked equipment sucb as
buUdozers and pertiaps smaU forklifts, most vehides should be able to travd to a designated area witb UtUe lost time.
Place temporary "caps" over neaiby catcb basins or manhole covers so Uiat if a spiU occurs it is prevented from entering
Uie storm drain.
Examoles of Hrfftttive PmoranK
The SpiU Prevention Conuol and Countomeasure (SPCQ Plan, which is required by law for some facUities, is an
effective program to reduce tbe number of accidental ^Uls.
• Tbe City of Palo Alto has an effective progiam for commerdal vehicle .viTvice faciliti<^- Many of Uw program's
elements, including speciflc BMP guidance and lists of equipment suppUers, arc also applicable to industrial
faciUties.
REFERENCES
Best Management Practices for Automotive-Related Industries, Santa Clara Valley Nonpoint Source Pollution Control
Program, 1992.
Best Management Practices for Industrial Storm Water Pollution Conuol, Santa Clara
VaUey Nonpoint Source PoUution Control Program, 1992.
Storm Water Management for Industiial Activities: Developing Pollution Prevention Plans, and Best
Management Practices, EPA 832-R-92-006. USEPA, 1992.
Water QuaUty Best Managemeni Practices Manual, Cily of Seattie, 1989.
Industrial Handbook 4-12 March, 1993
ACTIVITY: VEHICLE AND EQUIPMENT WASHING & STEAM CLEANING
TO SUMP
Applications
Manufacturing
Material Handling
Cyehicle Maintenance^
Construction^
Commercial Activities^
Roadways
Waste Containment
C^^sekeeping PracticM^
DESCRIPTION
Prevent or reduce the discharge of poUutants to storm water from vehicle and equipment
washing and steam cleaning.
APPROACH
• Consider off-site conunercial washing and steam cleaning businesses.
• Use designated wash areas, preferably covered to prevent contaa wiUi storm water
and bermed to contain wash water.
• Discharge wash water to sanitary sewer, after contacting local sewer authority to fmd
out if preoeatment is required.
• Educate employees on poUution prevention measures.
• Consider filtering and recycUng wash water.
• Do not peimit steam cleaning wash water to enter the storm drain.
• For a quick reference on disposal altematives for spedfic wastes see Table 4.1, SCI.
REQUIREMENTS
• Capital costs vary depending on measures implemented.
- Low cost ($5(X)-1,000) for berm construction.
Medium cost (S5,(X)0-20,0(X)) for plumbing modifications (including re-routing
discharge to sanitaiy sewer and instalUng simple sump).
High cost ($30,000-150,000) for on-site ueatment and recycUng.
• O&M costs increase with increasing capital investmenL
• Maintenance
Berm repair and patching.
In^>ection and maintenance of sumps, oU/water separators, and on-site treatment/
recycling units.
LIMITATIONS
• Some municipaUties may require pretreatment and monitoring of wash water dis-
charges to Uie sanitary sewer.
• Steam cleaning can generate significant poUutant concenuations requiring permitting,
moniUKing, pretreatment, and inspections. The measures outlined in tbis fact sheet
are insuffidenl to address aU Uie environmental impacts and compliance issues related
to steam cleaning.
Targeted Constituents
% Sediment
# Nutrients
% Heavy Metals
# Toxh Materials
O Floatable Materials
9 Oxygen Demand-
ing Substances
# Oil & Grease
O Bacteria Sc Viruses
W Ukely to Have Sigruficant Impact
O Probable Low or
Unknown Impact
Implementation
Requirements
Q Capital Costs
O O&M Costs
O Maintenance
O Training
High O Low
SC3
Best^
Management^
Practices^
Industrial Handbook 4-13 March, 1993
Additional Information — Vehicle and Equipment Washing and Steam Cleaning
Washing vehicles and equipmem outdoors or in areas where wash water flows onto the ground can pollute stonn water.
If your CaciUty washes or steam deans a large number of vehicles or pieces of equipment, consider contracting out Uiis
woric to a commercial business. These businesses are better equipped to handle and dispose of the wash waters properly.
Contracting out tbis work can also be economical by eliminating the need for a separate washing/cleaning operation at
your facility.
If washing/cleaning must occur on-site, consider washing vehicles inside tbe buUding to control Uie targeted constituents
by directing Uiem to the sanitary sewer where Uicy can be pretreated or sent directiy to tbe sanitary ueatment facility.
Washing operations outside should be conducted in a designated wash area having Uie following cliaracteristics:
• Paved with Portland cement concrete,
• Covered or bermed to prevent contact witb stoim water,
• Sloped for wash water collection. ^
• Discharges wash water to thc sanitary or process waste sewer, or to a dead-end sump. Discbarge pipe should have a
positive control valve that allows switching between Uic storm drain and sanitary or process sewer,
• (Tleariy designated, and
• Equipped widt an oU/watcr separator (sec Chapter 5, TC7, OU/Watcr Separators and Water QuaUty Inlets).
Examples of Effective PmpT?mi<^
Thc City of Palo Alto has an effective program for commerdal vehide service fadUties. Many of Uie program's
elements, including specific BMP guidance and Usts of equipment suppliers, are appUcable to industrial vehicle service
facilities.
The U.S. Postal Service in West Saaamento has a new vehicle wash system Uiai collects, fUters, and recycles thc wash
water.
REFERENCES ™
Best Management Practices for Automotive-Related Industries, Santa Clara VaUey Nonpoint Source PoUution Control '^l
Program, 1992.
Best Management Practices for Industrial Storm Water PoUution Control, Santa (Tiara VaUey Nonpoint Source PoUution
Control Program, 1992.
Stonn Water Managemeni for Industrial Activities: Devetoping PoUution Prevention Plans, and Best Management
Practices, EPA 8320R-92-006, USEPA. 1992.
Water QuaU^ Best Management Practices Manual. City of Seattie. 1989.
Industrial Handbook 4-14 March, 1993
ACTIVITY: VEHICLE AND EQUIPMENT MAINTENANCE AND REPAIR
DIKE TO PREVENT
SPILLSI-EAKS
FROIM ENTERING STORM DRAIN
Roadways
Waste Containment
(^Housekeeping Practic^^
Applications
Manufacturing
DESCRIPTION
Prevent or reduce tbe discbarge of pollutants to storm water from vehicle and equipment
maintenance and repair by running a dry shop.
APPROACH
• Keep equipmenl clean, don't allow excessive build-up of oil and grease.
• Keep drip pans or containers under tbe areas that might drip.
• Do not change motor oil or pcrfoim equipment maintenance in non-appropriate areas.
Use a vehicle maintenance area designed to prevent storm water pollution.
• Inspect equipment for leaks on a regular basis.
• Segregate wastes.
• Make sure oU filters arc completdy drained and crashed before recycling or disposal..
• Make sure incoming vehicles are checked for leaking oU and fluids.
• Clean yard storm drain inlets(s) regulariy and espedaUy after large stonns.
• Do not pour materials down drains or hose down work areas; use dry sweeping.
• Store idle equipment under cover.
• Drain aU fluids from wrecked vehicles.
• Recycle greases, used oU OT OU fUlcrs, antifreeze, cleaning solutions, automotive
batteries. hydrauUc, and transmission fluids.
• Switch to non-toxic chemicals fOT maintenance when possible.
Clean smaU spUls witb rags, general clean-up wiUi damp mops and larger spUls wiUi
absorbent material.
• Paint signs on storm drain inlets to indicate that they are not to receive Uquid OT soUd
wastes.
• Train employees.
• Minimize use of solvents.
• FOr a quick reference on disposal alternatives for spedfic wastes see Table 4.1, SC 1.
REQUIREMENTS
• Costs (Capital. O&M) - Should be low. bul wUl vary depending on tbe size of Uie
faciUty.
• Maintenance - Should be low if procedures for the approach are foUowed.
LIMITATIONS
• Space and time limitations may preclude aU wOTk being conducted indoOTS.
• It may not be possible to contain and clean up spiUs from vehicles/equipment brought
on-site after woridng hours.
• Drain pans (usuaUy 1 ft. x 1 ft) are generally too smaU to contain antifreeze, which
may gush fhMn some vehicles, so drip pans (3 ft x 3 fL) may have to be purdiased or
falxicated.
• Dry floor cleaning metiiods may not be suffident for some spUls. Use Uiree-step
metiiod instead.
• Identification of engine leaks may require some use of solvents.
Targeted Constituents
O Sediment
O Nutrients
% Heavy Metals
# Toxh Materials
O Floatable Materials
O Oxygen Demand-
ing Sul>stances
# Oil & Grease
O Bacteria & Viruses
# Ukely to Have SIgnilicant Impact
O Probable IJOW or Unknown Impact
Implementation
Requirements
O Capital Costs
Q O&M Costs
Q Maintenance
O Training
High O Low
SC4
Best'
Management
Practices'*
Industrial Handbook 4-15 March, 1993
Additional Information — vehicle and Equipment Maintenance and Repair
Vehicle or equipment maintenance is a potentiaUy significant source of storm water poUution. Activities tliat can
contaminate suxm water include engine repair and service (parts cleaning. spiUed fueL oU. etc.), replacement of fluids,
and outdoor equipment storage and paiking (drippmg engines). For further information on vehicle or equipment
servidng, see SC2. Vehicle and Equipmenl Fueling, and SC3, Vehicle and Equipmenl Washing and Steam Qeaning.
Waste Reduction
Parts are often cleaned using solvents such as uicbloroeUiylene, 1,1,1-uichloroetbane or meUiylene chloride. Many of
Uiese cleaners are harmful and must be disposed of as a hazardous waste. Geaning wiUiout using Uquid cleaners (e.g.
wire brush) whenever possible reduces waste. Prevent spills and drips of solvents and cleansas to die shop floor. Do aU
Uquid deaning at a centralized station so tbe solvents and residues stay in one area. Locate drip pans, drain boards, and
drying racks to direct drips back into a solvent sink or fluid holding tank for re-use.
Safer Alternatives
If possible, eliminate OT reduce the amount of hazardous materials and waste by substituting non-hazardous or less
h^ardous materials. For example:
• Use non-caustic detergents instead of caustic cleaning agents for parts cleaning (ask your suppUcr about altemative
cleaning agents).
• Use detergent-based or water-based cleaning systems in place of OTganic solvent degreaseis. Wash water may
require treatonent before it can be discharged to tbe sewer. Contaa your local sewer authority fOT more information.
• Replace chlorinated OTganic solvents (1,1,1-tricbloroethane, methylene chloride, etc.) with non-chlorinated solvents.
Non-cbloiinated solvents like kerosene or inineral spirits are less toxic and less expensive to dispose of prcperly.
Check list of active ingredients to see whether it contains chlorinated solvents. Tbe "chloi" teim in(Ucates Uiat die
solvent is chlcMinated.
• Choose cleaning agents Uiat can be recycled.
• Contaa your suppUer OT refer to trade journals for more waste minimization ideas.
Redudng tbe number of scdvents makes recycling easier and reduces hazardous waste management costs. Often, one
solvent can perform a job as weU as two different solvents.
Recycling
Separating wastes aUows for easier recycling and may reduce treatment costs. Keep hazardous and non-hazardous
wastes separate, do not mix used oU and solvents, and keep chlorinated solvents (Uke 1,1,1-aichloroetbane) separate
from non-chlorinated solvents (Uke kerosene and mineral spirits).
Many products made of recycled (Le., refmed or purified) materials are available. Engine oU. transmission fluid,
antifreeze, and hydrauUc fluid are available in recycled form. Buying recycled products suppOTts tbe market for recyded
materials.
.Spin Lf^kriftan Tip
Oean leaks, drips, and other ^iUs witb as UiUe water as possible. Use rags for small spills, a damp mop fOT general
cleanup, and dry absorbent material for larger spiUs. Use the following Uuee-step meUiod for cleaning floors:
1. Clean ^ills wiUi rags OT other absortient materials.
2. Sweep floor using dry absorbent material
3. MopflOOT. Mopwatermay be discharged to the sanitary sewer via a toUelOT sink.
Industriai Handbook 4 - 16 March, 1993
Additional Information — vehicle and Equipment Maintenance and Repair
Good Hoiisekeq^iny
Also consider die foUowing measures:
• Avoid hosing down your work areas. If wwk areas are washed, direct wash water to sanitary sewer.
• CoUect leaking or dripping fluids in drip pans or containers. Fluids are easier to recycle if kept separate.
• Keep a drip pan under the vehide while you uncUp hoses, unscrew fUters, or remove other parts. Use a drip pan
under any vehide Uiat might leak while you work on it to keep splatters or drips off die shop floor.
• PrompUy transfer used fluids to the proper waste or recycling drums. Don't leave fuU drip pans or other open
containers lying around.
Do not pour Uquid waste to floor drains, sinks, outdoor storm drain inlets, or other storm drains or sewer connections.
Used or leftover cleaning solutions, solvents, and automotive fluids and oU are toxic and should not l>e put in tbe sanitary
sewer. Post signs at sinks to remind employees, and paint stendls at outdoor drains to teU customer and otbers not to
pour wastes down drains.
on fUters disposed of in trash cans OT dumpsters can leak oU and contaminate storm water. Most municipaUties prohibit
OT discourage disposal of these items in soUd waste faciUties. Place Uie oU filter in a funnel over Uie waste oU recycling
or disposal collection tank to drain excess oU before disposal. Oil fUters can be crushed and recyded. Ask your oU
suppUer OT recycler about recycling oU filters.
Put pans under leaks to coUea fluids for proper recycling or disposal Keeping leaks off Uie ground reduces Uie potential
fOT Stoim water contamination and reduces cleanup time and costs. If the vehicle or equipment is to be stored outdoors,
oU and olher fluids should be drained first
Designate a special area to diain and replace motor oU, coolant, and other fluids, where there are no coimections to thc
stonn drain or tbe sanitary sewer and drips and spills can be easUy cleaned up.
Be especially careful witb wrecked vehicles, whether you keep them indoors OT out, as well as vehides kept on-site fOT
scrap OT salvage. Wrecked or damaged vehicles often drip oU and other fluids for several days.
• As Uie vehicles arrive, place drip pans under them immediately, even if you believe that Uie fluids have leaked out
l>efore the car reaches your shop.
• BuUd a shed or temporary roof over areas where you park cars awaiting repair or salvage, especially if you handle
wrecked vehkrles. BuUd a roof over vehicles you keep for parts.
• Elrain aU fluids, including air conditioner coolant, from wrecked vehicles and "part" cars. Also drain engines,
transmission, and other used parts.
• Store cracked batteries in a non-leaking secondary container. E>o this witii aU cracked batteries, even if you think aU
tbe add has drained out If you drop a battery, treat it as if it is cracked. Put it into the containment area untU you
are sure it is not leaking.
Examples of EfTective Proyranis
Thc City of Palo Alto bas an effective program for commerdal vehicle service fadlities. Many of Uic program's
elements, including specific BMP guidance and Usts of equipment suppliers, are also appUcable to industrial vehicle
service fadUties.
Pick N PuU Auto Dismantiers in Rancho COTdova drains all fluids from automobUes hefore Uiey enter tiie yard.
Ecology Auto Wrecking in Rialto is surrounded by a steel plate/concrete fence and has a completely paved lot Uiai is
graded to a central low point. CoUected storm water is channeled Uirough as underground drainage system of darifieis
Industrial Handbook 4-17 March, 1993
Additional Information — Vehicle and Equipment Maintenance and Repair
and Uicn stored in a 60,000 gaUon UST before being processed Uirough a fUtcr system. In addition, Uie work area is
covered, ventilated and has an additional sump. Vehicle fluids are drained in this area and segregated foe recycling.
AU Auto Parts, Fontana, has a complete water recycUng system in a 10,000 square foot concrete slab surrounded by a
cuib tiiat contains aU Uie runoff and sends it to Uie recycUng system. AU receiving, dismantiing, and shipping occurs on
Uie slab.
REFERENCES
Best Management Practices for Automotive-Related Indusuies, Santa Clara Valley Nonpoint Source PoUution Conttol
PiRgram, 1992.
Best Managemeni Practices fOT ControUing OU and Grease in Urtian Stoim Water Runoff. G. S. Silvennan. CL al. 1986
Enviroomental Professional, VoL 8. pp 351-362.*
Best Management Practices fOT Industrial Storm Water PoUution Control. Santa Clara VaUey Nonpoint Source PoUution
Control Program, 1992.
Faa Sheet - Waste Reduction for Automotive Repair Shops; DTSC. 1989.
Hazaidous Waste Reduction Assessment Handbook - Automotive Repair Shops; DTSC. 1988.
Hazardous Waste Reduction C3ieckUst - Automotive Repair Shops; DTSC. 1988.
StOTm Water Management for Industrial Activities: Developing Pcrflutioo Prevention Plans, and Best Management
Practices, EPA 832-R-92-006, USEPA, 1992.
Industrial Handbook 4-18 March, 1993
ACTIVITY: OUTDOOR LOADING/UNLOADING OF MATERIALS Applications
Manufacturing
C^^^Material HandHng~^
Vehicle Maintenance
"^Construction
'Commercial Activities'^
Roadways
Waste Containment
C^usekeeping Practic^^
DESCRIPTION
Prevent or reduce tbe disdiarge of poUutants to storm water from outdoor loading/
unloading of materials.
APPROACH
• Park tank tracks or deUvery vehicles so tbat spUls or leaks can be contained.
• Cover the loacUng/unloading docks to reduce exposure of materials to rain.
• Seal OT doOT skirt between ttaUer and buUding can also prevent exposure to lain.
• Design loading/unloading area to prevent storm water ranon:
grading or berming. and
position roof downspouts to direa storm water away from loading/utUoading
areas.
• Contain leaks during transfer.
• Use drip pans under hoses.
• Make sure foik lift operators are properly trained.
• Employee Ironing for spill containment and cleanup.
REQUIREMENTS
• Costs ((Capital, O&M) - Should be low except when covering a large loading/unload-
ing area.
• Maintenance
Conduct regular inspections and make repairs as necessaiy. Tbe firequency of
repairs wiU depend on the age of tbe fadlity.
Check kiading and unloading equipment regularly for leaks:
valves,
pumps,
flanges, and
connections.
LIMITATIONS
• Space and time limitations may preclude all uansfeis from being peribrmed indoors or
under cover.
• It may not be possible to conduct ttansfers only during dry weather.
Targeted Constituents
O Sediment
9 Nutrients
# Heavy Metals
# TOXIC Materials
9 Fhatable Materials
0 Oxygen Demand-
ing Substances
# Oil & Grease
O Bacteria & Viruses
W Ukely to Have
Significant Impact
O Probable Low or
Unknown Impact
Implementation
Requirements
Q Capital Costs
O O&M Costs
O Maintenance
Q Training
High O Low
805
Managements
Practices^—*
Industrial Handbook 4 -19 March, 1993
Additional Information — outdoor Loading/Unloadlng of Materials
The loading/unloading of materials usuaUy takes place outside. Loading or unloading of materials occurs in two ways:
malerials in containers OT direa Uquid uansfer. Materials spiUed, leaked or lost during loading/unloading may coUea in
Uie soil OT on other surfaces and t>e canied away by ranoff OT when Uie area is deaned. RainfaU may wash poUutants
from machinery used to unload or move m^tpriais Tbe loading or unloading may involve rail or truck transfer.
Ibc most important faaors in preventing these constituents from entering storm water is:
Linul exposure of material to rainfall.
• E^vent storm water runon.
• Check equipment regulariy for leaks.
• Contain spills during transfer operations.
Loading or uiUoading of Uquids should occur in Uie manufacturing building so Uiat any spills tiiat are nol completely
retained can be discharged to tbe sanitary sewer, treatment plant, or treated in a manner consistent wiUi local sewer
authorities and pennil requirements. Best management practices include:
• Use overhangs or door skirts lhat enclose tbe ttailer.
• Park tank tracks during deUvery so Uiat spUIs OT leaks can be contained.
• DesignJoading/unloading area to prevent storm water ranon which would include grading OT berming tbe area, and
positioning roof downspouts so Uiey direa storm water away frcm tbe loading/unloading areas.
• Check loading and unloading equipmenl regularly fOT leaks, including valves, pumps, flanges and connections.
Look for dust or fumes during loading or unloading operations.
• Use a written qierations plan Uiat describes procedures for loading and/or unloading.
• Have an emergency spiU cleanup plan readily available.
• Employees trained in spUI containment and deanup should be present during the loading/unloading.
• Establish depots of cleanup materials next to or near each loading/uiUoading area, and train employees in their use.
• FOT loading and unloading tank tracks to above and lielow ground storage tanks, the foUowing procedures should be
used.
The area where Uie transfer takes place should be paved. If the Uquid is reactive witb Uie asphalt. Portland
cemenl should be used to pave Uie area.
Transfer area should be designed to prevent ranon of storm water £rom adjacent areas. Sloping tbe pad and
using a cuib. like a speed bump, around die uptiiU side of tiie transfer area shouki reduce ranon.
Transfer area should be designed to prevent ranoff of spiUed Uquids frxim Uie area. Sloping Uie area to a dram
should prevent ranoff. The drain should be connected to a dead-end sump or to die sanitary sewer. A positive
coDin^ valve should be instaUed on the drain.
• FOT transfer from raU cars to storage tanks that must occur outside, use the following procedures:
Drip pans should be placed at locations where spillage may occur, such as hose connections, hose reels, and
fUler nozzles. Use drip pans when making and breaking connections.
Drip pan systems should be installed between tbe raUs to coUect spUIage from uink cars.
REFERENCES
Besl Management Practices for Induslrial Storm Water PoUution Control Santa Clara VaUey Nonpoint Source Pollution
ConODl Program, 1992
Stotm Water Managemeni for Industrial Activities: Developing Pollution Prevention Plans, and Best Management
Practices, EPA 832-R-92-006, USEPA, 199Z
Water QuaUty Besl Managemeni Practices Manual City of Seattle, 1989.
Industrial Handbook 4 - 20 March, 1993
ACTIVITY: OUTDOOR CONTAINER STORAGE OF UQUIDS
COVER TO MINIMIZE
STORM WATER
DIKE TO CONTAIN SPILLS/STORM WATER
Applications
Manufacturing
Material Handling
Vehhie Maintenance
CConwnercial Activit^^
Roadways
Waste Containment
C^ousekeeping Practic^^
DESCRIPTION
Prevent OT reduce tbe discharge of pdlutants to storm water from outdoor container storage
areas by instaUing safeguards against acddental releases, installmg secondary containment,
conducting regular inspections, and training employees m standard operating procedures
and SpiU cleanup techniques.
APPROACH
• Protea materials from rainfall ranon, ranoff, and wind dispersal:
Store materials indoors.
Cover thc storage area wiUi a roof.
Minize storm water ranon by enclosing the area or buiding a berm around it.
Use "doghouse" for storage of Uquid conuiiners.
Use covered dumpsteis fOT waste produa containers.
• Storage of oU and hazardous materials must meet spedfic Federal and State standards
induding:
SpiU Prevention Control and Countermeasure Plan (SPCC) Plan,
secondary containment,
integrity and leak detection monitoring, and
emergency preparedness plans.
• Train operator on proper storage.
• Safeguards against acddental releases:
overflow protection devices to wara operator or automatic shut down transfer
pumps,
protection guards (bollards) around tanks and pipmg to prevent vehicle or forkUft
damage, and
clear tagging or labeUng, and restricting access to valves to reduce human error.
• Benn or surround tank or container witb secondary containment system:
dikes, liners, vaults, OT double waUed tanks.
• Some municipalities require tbat secondary containment areas be connected to
the sanitary sewer, prohibiting any hard connections to the stonn drain.
• FadUties wiUi "spiU ponds" designed to intercept, treat, and/OT divert spiUs
should contaa the appropriate regulatory agency regarding envirinmehcU
compUance.
REQUIREMENTS
• Cost (Capital, O&M)
WlU vary depending on the size of Uie faciUty and Uie necessary controls.
• Maintenance: Condua routine weekly inspections.
LIMITATIONS
• Storage sheds often must meet building and fire code requirements.
Targeted Constituents
O Sediment
O Nutrients
% Heavy Metals
9 Toxh Materials
O Floatable Materials
9 Oxygen Demand-
ing Substances
O Oil & Grease
O Bacteria & Viruses
W Ukely to Have
Significant Impact
o Probable Low or
Unimown Impact
Implementation
Requirements
O Capital Costs
O O&M Costs
O Maintenance
O Training
High O Low
SC6
Best^
Management
Practices^
Industrial Handbook 4-21 March, 1993
Additional Information — Outdoor Container Storage of Liquids
Acddental releases of materials from aboveground Uquid storage tanks, drams, and dumpsters present the poten-
tial fOT contaminating storm wateis wiUi many different poUutants. Materials spilled, leaked OT lost from storage
containers and dumpsters may accumulate in soils or on tbe suifaces and be carried away by storm water ranoff.
These source controls apply to containers located outside of a buUding used to temporarily store Uquid materials.
Il should be noted tbat the storage of reactive, ignitable, or flammable liquids must comply witb fire codes.
Container Manaoement
To limit tbe possibility of storm water poUution, containers used to store dangerous waste or other Uquids sfaoiUd
be kept inside tbe buUding unless tbis is impractical due to site constraints. If tbe containers are placed outside, tiie
foUowing procedures sboiUd be employed:
• Dumpsters used to store items awaiting uansfer to a landfiU should be placed in a lean-to stracture or other-
wise covered, dumpsters shaU be kept in good condition witiiout corrosion or leaky seams.
• Gait>age dumpsters shaU be replaced if they are deteriorating to the point where leakage is occuning. It
shouki be kept undercover to prevent the entry of stonn water. Emptoyees should be made aware of Uie
importance of keeping tbe dumpsters covered and free from leaks.
• A fillet sbouldiie placed on boUi sides of the curb to fadUtatc moving Uie dumpster.
• Waste container drums should tie kept in an area such as a service bay. If drums are kept outside, they must
be stored in a lean-to type suucture, shed or waUc-in container to keep rainfaU from reaching Uie drums.
Storage of reactive, ignitible, OT flammable liquids must comply witb the fire codes of your area. Practices listed
below should be employed to enhance tbe fire code requirements.
• Containeis should be placed in a designated area.
• Designated areas should be paved, free of cracks and gaps, and impervious in order to contain leaks and spUls.
• Liqukl waste should be surrounded by a curb OT dike to provide the volume to contain 10 percent of the
volume of all <rf Uie containers or 110 perceni of tbe volume of Uie largest container, whichever is greater.
Tbe area inside tbe cuifo should slope to a drain.
FOT used oil OT dangerous waste, a dead-end sump should be instaUed in the drain.
All other Uquids should be drained to the sanitary sewer if available. Tbe drain musl have a positive control
such as a tock, valve, or plug to prevent release of contaminated liquids.
• Tbe designated storage area should be covered.
• Containers tised fOT Uquid removal by an employees musl be placed in a containment area.
A drip pan should be used at aU times.
• Drums stored in an area where unauUiorized persons may gain access musl be secured to prevent acddental spiUage,
pUferage, OT any unauUiorized use.
• Emptoyees trained in emergency spUl deanup procedures should be present when dangerous waste, Uquid chemicals,
or otiier wastes are loaded or unloaded.
Tbe most common causes of unintentional releases:
• Extemal corrosion and structural failure,
• Installation problems,
• SpUls and overfUls due to operator error,
• FaUure of piping systems (pipes, pumps, flanges, coupUngs, hoses, and valves), and
• Leaks during pumping of Uquids or gases from track or railcar to a storage fadUty or vice versa.
Operator Trainino/Safeouards
WcU-trained employees can reduce human errors Uiat lead to acddental releases or spiUs. Employees should be fiamiliar
wiUi tbe SpiU Prevention Conttol and Countermeasure Plan. The employee should have the tools and knowledge to
Industriai Handbook 4-22 March, 1993
Additional Information — outdoor container storage of Uquids
immediately begin deaning up a spiU if one should occur. Operator errors can be prevented by using engineering safe
guards and thus redudng accidental releases of poUutant Safeguards include:
Overflow protection devices on tank systems to wara Uie operator to automatically shutdown ttansfer pumps when
Uie tank reaches fuU capadty,
Protective guaids (bollards) around tanks and piping to prevent vehicle or forkUft damage, and
Clearly tagging or labeling aU valves to reduce human error.
Tank systems should be inspected and tank integrity tested regulariy. Problem areas can often be detected by visuaUy
inspecting die tanks frequentiy. Problems or potential problems should be corrected as soon as possible. Registered and
spedfically ttained professional engineers can identify and conect potential problems such as loose fittings, poor welding
and improper or powly fitted gaskets fw newly instaUed tank systems. Tbe tank foundations, connections, coatings, and
tank waUs and piping systems also should be inspected- Inspection for corrosion, leaks, cracks, scratt±es in protective
coatings, or oUier physical damage that may v^eaken Uie tank system should be a part of regular integrity testing.
Secondary Containment
Tanks should be benned OT surrounded by a secondaiy containment system. Leaks can be detected more easily and spiUs
can be contained wben a secondary containment systems are installed. Beims, dikes, Uners. vaults, and double-waU tanks
are examples of secondary containment systems.
One of Uie best protective measures against contamination of storm water is dUdng. Containment dUces are benns or
reuiining walls Uiat are designed to hold spiUs. DUdng is an effecuve poUution prevention measure for above ground
storage tanks and railcar OT tank ttuck loading and unloading areas. Tbe dUce surrounds the area of concem and holds Uie
spm, keeping spUl materials separated from die stonn water side of Uie dUce area. DUdng can be used in any industtial
fadlity, but it is most commonly used for conttoUing large spiUs or releases from Uquid storage areas and Uquid transfer
areas.
For single-wall tanks, containment dUces should be large enough to hold Uie contents of Uie storage tank for the fadUty
plus rain water. FOT tracks, dUced areas should be enable of holding an amount equal to Uic volume of Uie tank ttuck
compartment DUced constraction material should be sttong enough to safely bold spiUed materials. Dike materials can
consist of earth, concrete, syntiietic materials, metal or otiier impervious materials. Sttong adds or bases may read wiUi
mettU conuiiners, concrete, and some plastics. Where strong adds or bases or stored, alternative dUce materials should be
COTisidered. More active organic chemicals may need certain special Uners for dikes. DUces may also be designed wiUi
impermeable materials to increase containment capabiUtics. DUces should be inspected during or after significant storms
or spiUs to check for washouts or overflows. Regular checks of containment dikes to insure Uie dflces are capable of
holding spUls shouki be conducted. InabiUty of a stracuire to retain storm waler, dike erosion, soggy areas, or changes in
vegetation indicate problems wiUi dike stractures. Damaged areas should be patched and stabUized immediately. Earthen
dikes may require special maintenance of vegetation such as mulching and irrigation.
Curbing is a barrier tiiat surrounds an area of concem. Curbing is similar to containment dUcing in tbe way dial it prevents
spiUs and leaks from being released into Uie environment The curbing is usually smaU scaled and does not contain large
spiUs like dUcing. Curbing is common at many fadUties in small areas where handling and transfer Uquid materials occur.
Curbing can redired contaminated storm water away from die storage area It is useful in areas where liquid materials are
transferred from one container to anotiier. Asphalt is a common material used for curbing; however, curbing materials
inciude earth, concrete, synthetic materials, metal or otiier impenenable materials. SpUled materials should be removed
'immediately from embed aieas to allow space for futtire spUls. Curbs should bave manuaUy<onuolled pump systems
rather Uian common drainage systems for coUection of spiUed materials. Tbe curbed area should be inspcaed regulariy to
clear clogging debris. Mjuntenancc should also be conducted frequentiy to prevent overflow of any spiUed materials as
curbed areas are designed only for smaller spiUs. Curbing bas Uie following advantages:
Excdlent runon conttol
Inexpensive.
Ease of installment
Provkles option to recycle materials spUled in curb areas, and
Common industry practice.
Industrial Handbook 4 - 23 March, 1993
Additional Information — Outdoor Container Storage of Uquids
Maintenance
• Weekly inspection should be considered and indude:
Check for external corrosion and structural failure.
Check for spUls and overfills due to operaux- enor.
Check for failure of piping system (pipes, pumps, flanges, coupling, hoses, and valves).
Check for leaks or spills during pumping of Uquids or gases fiom track OT laU car to a storage fadUty or vice
versa,
VisuaUy inspea new tank or container installation loose fittings, poor welding, and improper or powly fitted
gaskets, and
In^iea tank foundations, connections, coatings, and tank walls and piping system. Look fOT corrosion, leaks,
cracks, scratches, and other physical damage dial may weaken the tank or container system.
Examples of EfTeaive Programs
TTic "doghouse" design bas been used to store smaU liquid containers. Thc roof and flooring design prevent contaa wiUi
direa rain OT runoff. The doghouse bas two soUd stracmral walls and two canvas covered walls. Thc flooring is wire
mesh about secondary containment Tbe unit has been used successfuUy al Lockbeed MissUe and Space Company in
Siranyvale.
REFERENCES
Best Management Practices for Industrial Stonn Water PoUution Conttol Santa Clara VaUcy Nonpoint Source
PoUution Control Program, 1992.
Suxm Water Management for Industrial Activities: Developing PoUution Prevention Plans, and Besl Management
Practices, EPA 832-R-92-006, USEPA, 1992.
Water (QuaUty Best Managemeni Practices Manual City of Seattle, 1989.
Industrial Handbook 4 . id
^ • March, 1993
ACTIVITY' OUTDOOR PROCESS EQUIPMENT OPERATIONS AND • MAINTENANCE
DIKE TO CONTAIN
SPILLS/STORM WATER
Commercial Activities^
Roadways
Waste Containment
C^ousekeeping Practice^
Applications
^_^^anufacturing~^^
Material Handling
Vehicle Maintenance
DESCRIPTION
Prevent or reduce die discbarge of poUutants to storm water from outdoor process equip-
ment operations and maintenance by redudng Uie amount of waste created, enclosing or
covering aU or some of Uie equipment instaUing secondary conttdnment and ttaining
employees.
APPROACH
• Alter tbe activity to prevent exposure of poUutants to storm water.
• Move activity indoors.
• Cover Uie area wiUi a pennanent roof.
• Minimize contaa of storm water with outside manufacturing operations through
berming and drainage routing (ran on prevention).
• Connea process equipment area to pubic sewer or facUity wastewater treatment
system.
• Clean regularly tiie stoim drainage system.
• Use cau± basin filttation inserts (Chapter 5, TC6, Media FUttation) as a means to
capttire particulate poUutants.
• Some munidpalities require tbat secondary containment areas (regardless of size) lie
connected to tbe saiutary sewer, prohibiting any hard connections to Uie stoim drain.
REQUIREMENTS
• Costs (Capital O&M)
Variable depending on the complexity of the operation and tiie amount of control
necessary for storm water poUution control.
• Maintoiance
Routine preventive maintenance, including cheddng process equipment for
leaks.
LIMITATIONS
• Providing cover may be expensive.
• Space limitations may preclude enclosing some equipment
• Storage sheds often must meet building and fire code requiremenls.
Targeted Constituents
# Sediment
O Nutrients
% Heavy Metals
9 Toxic Materials
O Fhatable Materials
O Oxygen Demand-
ing Substances
# Oil & Grease
O Bacteria & Viruses
W Ukely to Have Significant Impact
O Probable Low or
Unknown Impact
Implementation
Requirements
% Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
SC7
Best^
Management
Practices^
Industrial Handbook 4-25 March, 1993
Additional Information — outdoor process Equipment Operations and Maintenance
Outside process equipment operations can conmminate storm water ranoff. Activities, such as rock grinding OT crash-
ing, painting OT coating, grinding or sanding, degrcasing OT parts cleaning, landfUls. waste piles, wastewater and solid
waste treatment and disposal, and land appUcation are process operations that use hazardous materials and lhat can lead
to contamination of storm water ranoff. PoUulants from the wastewater and soUd waste tteatment and disposal areas
result firom waste pumping, additions of treatment chemicals, mixing, aeration, clarification, and soUds dewatering.
Possible Storm water contaminants include heavy metals, toxic materials, and oU and grease. Waste spiUed, leaked, OT
lost from outdoOT process equipment operations may buUd up in soils OT on oUier surfaces and be carried away by suxm
water ranoff. There is also a potential for Uquid waste from lagoons or surface unpoundments. associated with outtloor
equipment operations, to overflow to surface waters OT soak tiie soU, which can be picked up by storm water runoff.
The preferred (and possibly tiie most economical) action to reduce stonn water poUution is to alter tiie nature of activity
such that poUutants are not exposed to storm water. This may mean perfoming Uie activity during dry periods only or
substituting benign materials for more toxic ones. Actions other tban altering tiie activity include enclosing tiic activity
in a building and connecting Uic floOT drains to die sanitary scwcr. The area used by tbe activity may tic so great as to
make endosure prohibitively expensive. Building cost can be reduced by nol covering tiie sides, and tiius eUminating
Uie need fOT ventilating and Ughting systems. When certain parts of tiic activity are tiic woisi source of poUutants, tiiose
pans can be segregated and enclosed OT covered.
Curbs can be placed around tiic immediate boundaries of tbe process equipment The storm drains from tiiese interiOT
areas can be connected to the fadlity's process wastewater system.
Reducing Uie amount of waste tiiat is created and consequentiy the amount dial must be stored or tteated is anotiier way
to reduce tiic potential for storm water contamination from outsuJc manufacmring activities. Waste reduction BMPs are
available for a wide range of indusuies and are designed to provide ideas and ways to reduce waste (see References).
Hvdranlic/Treatment Mndifiratinns
If suxm water becomes poUuted, it should be capnired and tteated. If you do nol have your own process wastewater
ttcattncnl system, conskkr discharging to die public sewer system. Use of Uie public scwcr might be allowed under tiic
foUowing conditions:
• If tiic activity area is very smaU Qess Uian a few hundred square feel), tiie local sewer autiiority may be wUIing to
aUow tiic area to remain uncovered witii tbe drain connected to die publk: sewer.
• Il may be possible under unusual drcumstances to connea a much larger area to Uic public sewer, as long as die rate
of suxm water discharges do not exceed Uic capadty of tiic wastewater treatment plant The storm water could be
stored during the suxm and Uien ttansferred to Uie pubUc scwcr when Uie nonnai flow is low, such as at night
The m^oriiy of tiie pollutants in stoim water are discharged over time by tiie small high frequency storms. Less
polluted runoff from tiie infrequent large sttxms can be bypassed to tiie storm drain. To implement tius BMP, a hydrau-
Uc evaluation of thc downstream sewer system should occur in consultation witii die local sewer autiiority.
Indusuies Uiat generate large volumes of process wastewater typicaUy have tiieir own treatment system tiiat discharges
directiy to Uic nearest receiving water. TTiese industries have tiic discretion to use their wastewater tteatment system to
tteat Storm water witiiin Uic constraints of tiieir pennit requirements for process treattnent It may also be possible for
Uie industty to discbarge tiie stoim water directiy to its effluent outfaU witiiout tteaunent as long as Uie total kjading of
Uie discharged process water and storm water does not exceed tiie loading had a storm water tteaonent device been used.
TTus could be achieved by redudng tiie loading from tiie process wastewater ttcattneni system. Check wiUi your Re-
gtonal Water (Quality Conttol Boanl, as Uiis option would be subjea to permil constraints and potentiaUy regular
monitoring.
Industrial Handbook 4 - 26 March, 1993
Additional Information — outdoor process Equipment Operations and Maintenance
REFERENCES
Best Management Practices for Industrial Storm Water PoUution Conttol Santa Clara VaUey Nonpoint Source PoUution
Conttol Program, 1992.
PubUcations That Can Woric For You!; CaUfomia Department of Toxic Substances Control Sacramento, CA 1991 (A
list and order form fOT waste minimization pubUcations frcan the State).
Stonn Water Management for Industrial Activities: Developing PoUution Prevention Plans, and Besl Management
Practices, EPA 832-R-92-006, USEPA, 1992.
Water (JuaUty Best Management Practices Manual City of Seattle, 1989.
Industrial Handbook 4-27 March, 1993
ACTIVITY" OUTDOOR STORAGE OF RAW MATERIALS, PRODUCTS,
• AND BY- PRODUCTS
Applications
Manufacturing
C^^^erial Handling^
Vehhie Maintenance
^Construction
"Commercial Activities'
Roadways
Waste Containment
a^usekeeping Practic^^
DESCRIPTION '
Prevent or reduce tbe discharge of poUutants to storm water from outdoor materiai and
product storage areas by enclosing or covering materials, installing secondary contain-
ment and preventing storm water ranon.
APPROACH
• Protea materials from rainfall ranon. ranoff and wind dispersal
Sttxe material indoors.
Cover thc storage area wiUi a roof.
Cover thc material witii a temporary covering made of polyetiiylenc. polypro-
pylene, or hypalon.
Minimize storm water nmon by enclosing the area or buUding a berm around die
area.
Use "doghouse" for storage of Uquid containers.
• Parking lots or oUier surfaces near buUc materials storage areas should be swept
periodically to remove debris blown or washed firom ston^e area.
• Install pcUel traps at storm water discbarge points where plastic peUets are loaded and
untoadcd. ,
• Ke^ Uquids in a designated area on a paved impervious surface widiin a secondary
containment
• Keep outdoor storage containers in good condition.
• Use beims and curbing.
• Use catt± basin fUttation inserts ((Tbapter 5, TC6, Media FUttation)
REQUIREMENTS
• Costs (Capital O&M)
Costs should be low except where large areas may have to be covered.
• Maintenance
Berm and curbing repair and patching.
LIMITATIONS
• Space limitations may preclude storing some materials indoors.
• Some munidpalities require that secondary containment areas (regardless of size) be
connected to the sanitary sewer, prohibiting any hard connections to Uic storm drain.
• Storage sheds often must meet building and fire code requirements.
Targeted Constituents
9 Sediment
O Nutrients
% Heavy Metals
# Toxic Materials
# Fhatable Materials
O Oxygen Demand-
ing Substances
# Oil & Grease
O Bacteria & Viruses
• Ukely to Have Significant Impact
O Probable Low or
Unknown Impact
Implementation
Requirements
Q Capital Costs
O O&M Costs
O Maintenance
9 Training
High O Low
808
Best
Management^
Practices^
Industrial Handbook 4-28 March, 1993
Additional Information — outdoor storage of Raw Materials, Products, and By-Products
Raw materials, by-products, finished products, containers, and material storage areas exposed to rain and/or
nmoff can pollute storm water. Stoim water can become contaminated by a wide range of contaminants when
materials wash off or dissolve into water OT are added to nmoff by spiUs and leaks.
Paved areas should be sloped in a manner that minimize die pooling of water on Uie site, particulariy witb
materials tiiat may leach poUuumts into stOTm water and/or groundwater, such as compost logs, and wood chips.
A minimum slope of 1.5 perceni is recommended.
Curbing shouki be placed along the perimeter of the area to prevent tiic runon of uncontaminated storm water
from adjacent areas as wcU as ranoff of storm water fnxn the stockpUe areas. The storm drainage system should
be designed to minimize the use of catcb basuis in Uie mteriOT of Uie area as Uiey tend to rapidly fiU wUh manu-
faauring material In Uiese cases, consider tiic u^ of tiie catt± basin insert fUter described in Chapter 5, TC6
(Media FUttation). Tbe area should be sloped to drain storm water to tiie perimeter where it can be coUected OT to
mtemal drainage alleyways where material is HOT stoclqpUed. If Uic raw material by-product, or product is a
Uquid, more information for outside storage of Uquuls can be found under SC6. OuutoOT Container Storage of
Liquids.
Examplffj
Tbe "doghouse" design has been used to store smaU Uquid cootaincis. The roof and flooring design prevent
contact wiUi direct rain or runoff. Thc doghouse has two scrfid structural walls and two canvas covered walls.
Thc flooring is wire mesh about secondary containment TTie unil bas been used successively at Lockbeed
Missile and Space Company in Suimyvale.
REFERENCES
Best Management Practices for Industtial Storm Water Pollution Control. Santa Clara VaUcy Nonpoint Source
PoUution Conttol Program, 1992.
Sttxm Water Management for Industrial Activities: Developing PoUution Prevention Plans, and Best Management
Practices, EPA 832-R-92-006, EPA, 1992.
Water (QuaUty Best Management Practices Manual City of Seattle, 1989.
II
Industrial Handbook 4-29 March, 1993
ACTIVITY: WASTE HANDUNG AND DISPOSAL
RECYCLABLE
WASTE
ONLY
Applications
Manufacturing
Material Handling
Vehhie Maintenance
"ignstructioji,
^Commercial Activities
Roadways
housekeeping Practic^^
DESCRIPTION *
Prevent or reduce the discharge of poUutants to storm water from waste handUng and
disposal by tracking waste generation, storage, and disposal reducing waste generation and
disposal through source reduction, re-use, and recycling; and preventing runon and ranoff
from waste managemeni areas.
APPROACH
Maintain usage inventory to Until waste generation.
Raw material substitution or elimination.
Process or equipment modification.
Production planning and sequencing.
SARA Titie HI, Section 313 requires reporting for over 300 listed chemicals and
chemical compounds. This requirement should be used to track these chemicals
although tbis is not as accurate a means of tracking as other approaches.
Track waste generated.
Characterize waste stream.
Evaluate the process generating thc waste.
Prioritize waste streams using: manifests, biennial reports, permits, environmen-
tal audits, SARA Tide III reports, emission reports, NPDES monitoring reports.
Inventory reports.
Data on chemical spills.
Emisstons.
Shelf Ufe expiration.
Use design data and review: process flow diagram, materials and applications diagram,
piping and instructions, equipmenl list, ptol plan.
Use raw material and production data and review: composition sheets, materials safety
data sheets (MSDS), batch sheets, produa OT raw material inventory records, produc-
tion schedule, opciattxr data log.
Use economic data and review:
Waste treattnent and disposal cost
Produa utiUly and econouuc cost
Operation and maintenance lalxx cost
Recycle materials whenever possible. .
Maintain Ust of and Uie amounts of materials disposed.
Waste segregation and separation.
Check industrial waste management areas for spills and leaks.
Cover, endose, or benn industrial wastewater management areas whenever possible to
prevent contaa wiUi ranon or ranoff.
Equip waste transport vehicles with anti-spUl equipment
Targeted Constituents
O Sediment
O Nutrients
# Heavy Metals
9 Toxh Materials
O Floatable Materials
O Oxygen Demand-
ing Suljstances
# Oil & Grease
O Bacteria & Viruses
• Ukely to Have Significant Impact
O Probable Low or Unknown Impact
Implementation
Requirements
O Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
SC9
Best^
Management
Practices^
Industrial Handtiook 4-30 March, 1993
ACTIVITY: WASTE HANDUNG AND DISPOSAL (Continue)
• Minimize spills and fugitive kisses such as dust or mist from loading systems.
• Ensure tbat sediments or wastes are prevented from being tracked off-site.
• Training and supervision.
• Stendl storm drains on the faciUty's ixoperty wilh prohibitive message regarding waste disposal.
• FOT a quick reference on disposal alternatives fOT specific wastes sec Table 4.1, SC 1.
• Consider ordering industty-specific OT waste stream-specific guidance from PPIC (see Appendix G).
REQUIREMENTS
• Costs (Coital O&M)
(Capital and O&M costs for these programs wiU vary substantially depending on die size of the faciUty and Uie
types of waste handled. Costs should low if there is an inventory program in place.
• Maintenance
None except fOT maintaining equipment fOT material tracking program.
LIMTTA-nONS
Hazardous waste tbat cannot lie re-used OT recycled must be disposed of by a Ucensed hazardous waste hauler.
Industrial Handbook 4-31 March, 1993
Additional Information — waste Handling and Disposal
Industtial waste management activities occur in areas that can contaminate stoim water and include landfiUs, waste piles,
wastewater and solid waste tteatment and disposal, and land appUcation. Typical operations which affea storm water
poUution may include waste pumping, tteatment chemicals storage, mixing, aeration, clarification, and solids dewater-
ing.
Waste Reduction
Waste spiUed, leaked, or lost from waste management areas or outside manufaauring activities may buUd up in soils or
in other surfaces and be carried away by stoim water ranoff. There is also a potential for Uquid waste from lagoons or
surface impoundments to overflow to surface waters or soak the soil where poUutants may be picked up by storm water
nmoff.
Waste reduction for manufacmring activiticsiis thc best way to reduce the potential of storm water contamination from
waste management areas. Reduction in tbe amount of industrial waste generated can be accompUshed using many
differeni types of source controls such as:
• Production planning and sequendng.
• Process OT equipment modification.
• Raw material substitution or elimination.
• Loss prevention and housekeeping.
Waste segregation and separation.
• Close loop recycling.
An approach to reduce storm water poUution from waste handUng and disposal is to assess process activities at tiie
fadlity and reduce waste generation. Tbe assessment is designed to fmd simations where waste can be eliminated or
reduced and emissions and environmental damage can be minimized. Tbe assessment involves coUecting process
spedfic infoimation, setting poUution prevention targets, and developing, screening and selecting waste reduction
options for further study. Starting a waste reduction program is economically beneficial because of reduced raw material
purchases and lower waste disposal fees. In addition, material ttacking systems to increase awareness about material
usage can reduce spiUs and minimize contamination, thus redudng tbe amount of waste produced.
Spill/Lcalc Contmi
Waste can be prevented from contaminating storm water by checking waste management areas for leaking containeis or
spills. Corroded or damaged containers can begin to leak at any time. Tiansfer waste from tiiese damaged containers
into safe containers. Dumpsters should be covered to prevent rain from washing waste out of boles or cracks in the
bottom of Uie dumpster. Leaking equipment including valves, Unes, seals, or pumps should be repaired promptiy.
Vehicles transporting waste stiould have spiU prevention equipmenl that can prevent spUls during transport The spiU
prevention equipment includes:
• Vehides equipped with baffles fOT Uquid waste.
• Tracks wiUi sealed gates and spUI guards for soUd waste.
Loading or imloading wastes can contaminate stoim water when tbe wastes are lost from the transfer. Loading systems
can also be used to minimize spills and fugitive emission losses such as dust or mist Vacuum ttansfer systems can
minimize waste loss.
Runon/Runoff Prevention
Stoim water ranon shouki be prevented fnxn entering the waste management area. Storm water poUution from ranon
can be prevented by enclosing Uic area OT buUding a berm around Uic area. OUier alternatives for reducing storm water
poUution include:
• Preventing the waste materials from directiy contacting rain.
Industrial Handbook 4-32 March, 1993
Additional Information — Waste Handling and Disposal
• Moving UlC activity indoOT after ensuring that aU safety concerns such as fire bazard and ventilation are addressed.
• Covering the area witb a pdmanent roof.
• Covering waste pUcs with temporary covering material such as reinforced tarpaulin, polyetiiylene, polyurethane,
polypropylene or hypalon.
To avoid ttacking materials off-site, tbe waste management area should be kept clean at aU times by sweeping and
cleaning up spills immcdiaidy. Vehides should never drive Uirough spills. If necessary, wash vehicles in designated
areas before Uicy leave tbe site, and control the wash water.
Minimizing the ranoff of poUuted storm water from land a^^Ucation of industrial waste on-site can be accomplished by:
• Choosing a site where:
slopes are under 6 percent ,
tiie soil is permeable
there is a low water table
it is tocated away frxxn wetlands or marshes
there is a dosed drainage system
• Avokling applying waste to die site:
wbcn it is raining
when die ground is frozen
when tbe groimd is saturated witb water
• Growing vegetation on land disposal areas to stabilize soils and reduce Uie volume of surface water runoff from die
site.
• Maintaining adequate barriers between tbe land appUcation site and Uie receiving waters. Planted strips are particu-
lariy good.
• Using erosion control tecbiuques
mulching and matting,
fUter fences,
straw bales,
diversion terracing,
sediment basins.
• Perfonning routine maintenance to ensure tbe erosion control OT site stabiUzation measures are working.
Examples of Effective Prooram?} The port of Long Beach has a state-of-Uie-art database for klentifying potential poUutant sources, documenting fadUty
management practices, and tracking poUutants.
REFERENCES
Best Management Practices for Industrial Storm Water PoUution Conttol Santa Clara VaUey Nonpoint Source Pollution
Control Program. 1992.
PubUcations Than Can Woric FOT You!; Califocnia Departtnent of Toxic Substances Conttol Sacramento. CA 1991 (A
list and order form fOT waste minimization publications from the State).
Stonn Water Management for Industiial Activities: Devetoping PoUution Prevention Pkms. and Besl Management
Practices, EPA 832-K-92-006, USEPA 1992.
Distribute List, PoUution Prevention Information aearingbousc, USEPA 1992.
Industrial Handbook 4-33 March, 1993
ACTIVITY: CONTAMINATED OR ERODIBLE SURFACE AREAS
Applications
Manufacturing
Material Handling
Vehhie Maintenance
donstruction^
Commercial Activities
C^Roadways^
Waste Containment
Housekeeping Practices
DESCRIPTION
Prevent or reduce tbe discharge of poUutants to storm water from contaminated or
erodible surface areas by leaving as much vegetation on-site as possible, minimizing soil
exposure time, stabUizing exposed soUs, and preventing storm water ranon and runoff.
APPROACH
This BMP addresses soils which are not so conuuninated as to exceed criteria (see Tide 22
(California Code of Regulations for Hazardous Waste Criteria), but tiic soU is eroding and
carrying pollutants off in tbe stoim water.
Contanunated or erodible surface areas can be conttoUed by:
Preservation of natural vegetation.
Re-vegetation,
Chemical stabilization.
Removal of contaminated soils, or
Gcosyntiictics.
FOT a quick reference on disposal altematives for specific wastes sec Table 4.1, SCI.
REQUIREMENTS
• Cost (Capital, O&M)
Except for preservation of natural vegetation, each of the above solutions can be
quite expensive depending upon the size of thc area.
• Maintenance
Maintenance should be minimal except possibly if inigation of vegetation is
necessary.
LIMITATIONS
Disadvantages of preserving natural vegetation or re-vegetating include:
• Requires substantial planning to preserve and maintain die existing vegetation.
• May not be cost-effective wiUi high land costs.
• Lade of rainfaU and/or poor soils may limit the success of re-vegetated areas.
Disadvantages of chemical stabilization indude:
• Creation of impervious surfaces.
• May cause harmful effects on water quaUiy.
• Is usuaUy more expensive Uian vegetative cover.
Targeted Constituents
0 Sediment
9 Nutrients
# Heavy Metals
# Toxic Materials
# Floatable Materials
9 Oxygen Demand-
ing Substances
9 Oil & Grease
O Bacteria & Viruses
• Ukely to Have
Significant Impact
O Probable Low or Unknown Impact
Implementation
Requirements
Q Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
SG10
Best'
Management
PracticesN
Industrial Handbook 4-34 March, 1993
Additional Information — Contaminated or Erodible Surface Areas
Of interest here arc areas wiUiin Uic industtial site tiiat are bare of vegetation and tiierefore subject to erosion. They may
or may not be contaminated from past OT current activities. Activity may OT may not be occurring in Uie area of interest
According w tiie Suite's General Industtial Activity Storm Water Pennit tiie SWPPP must include BMPs Uiat deal widi
Uiese simations. If tiic area is temporarily bare because of consuuction, see SC12, BuUding Repair, Remodeling, and
Consttuction.
CcMitaminated or credible surfaces can resuU from Uie human activities such as vegetation removal compacting or
disuirbing soil and changing nattiral drainage pattems. Industties must identify Uie areas of contaminated or erodible
surfaces. Thc areas may indude:
• Heavy activity where plants cannoi grow.
• SoU StockpUes.
• Steep slopes. .
• Constraction areas.
• DemoUtton areas.
• Any area where soU is disturbed.
The most effective way to conuol erosion is to preserve existing vegetation. Preservation of nauiral vegetation provides
a natural buffer zone and an o^^nunity for infUtration of storm water and allure of pollutants in tiie soU mattix. By
preserving stabilized areas, it minimizes erosion potential protects water quaUty. and provides aestiietic benefits. This
jwactice is used as a pennanent conttol measure. Vegetation preservation on-site should be planned before disttirbing die
site. Prescrvatton requires good site managemeni to mimmize tiic unpaa of constraction when constraction is underway.
Proper maintenance is important to ensure hcalUiy vegetation tiiat can conttol erosion. Different species. soU types, and
cUmatic conditions wiU require different maintenance activities such as mulcbing, feitiUzing. Uming. inigation. praning
and weed and pest conuol Maintenance should be perfonned regulariy especially during constniction phases.
Advantages of preservation of natural vegetation are:
• Can handle higher quantities of storm water runoff tiian newly seeded areas.
• Increases tiic fUtering capadly because vegetation and root systems are usually dense in preserved natural
vegetation.
• Enhances aesthetics.
• Provides areas for infiltration, thus reducing tbe quantity and velocity of storm waUTiunofL
• Allows areas where wUdlife can remain undisturtied.
• Provkles noise buffers and screens fw on-site operation.
• UsuaUy requires less maintenance Uian planting new vegetation.
TTie measure of chotoc is to leave as much native vegetation on-site as possible. Uiereby reducing or diminating die
problem. However, assuming tiic site akeady has conttmtinated OT erodible surface areas. Uierc are tiiree possible courses
of action:
1. Re-vegetatt die area if it is not in use and tiierefore not subjea to damage from site activities. In as much as
tiie area is already devoid of vegetation, special measures are Ukely necessary. Lack of vegetation may be
due to tiie lack of water aad/or poor soUs. Thc later can pertiaps be solved witii fertiUzatioa Or Uie ground
may simply be too compacted from prior use. Improving soU conditions may be sufficient to support
vegetation. If avaUable process wastewater can be used for irrigation, sec Consttuction Best Management
Practice Handbook fOT procedures to establish vegetation.
Industriai Handbook 4 . 35 L ,nni
^ •'^ March, 1993
Additional Information — contaminated or Erodlble Surface Areas
Chemical stabiUzation (for example Ugno suUate) can be used as an alternate in areas where temporary
seeding practices cannot be used liecause of season or cUmatt. It can provide immediate, effective, and
inexpensive eroston control. AppUcation rates and procedures recommended by die manufaaurer should be
foUowed as closely as possible to prevent Uie product from fonning ponds and creating large areas where
moisture cannoi penetrate die soil The advantages of chemical stabilization include:
• EasUy appUed to the surface.
• Effective in stabiUzing areas.
Provides immediate protection to soils dial are in danger of erosion.
Removal of contaminated soils is a last resort and quite expensive. The level and extent of die contamination
musl be determined. This detennination and removal must comply with State and Federal regulations,
permits must be acquired, and fees paid.*
4. Geosynthcttos indude Uiosc materials dial are designed as an impermeable hairier to contain or ccxitrol large
amounts of UquW OT soUd matter. Gcosyntiictics have been developed primarily for use in landfUls and surface
impoundments, and tiic technotogy is weU csttiblisbed. There are two general types of geosyntiietics:
geomembrancs(impermcable) and gcotextiles(permeablc).
• Geomembranes are composed of one of three types of impermeable materials: clastCHners(rabbers),
tiiermopkisics(plastics), or a cixnbination of Uiesc two types of materials. The advantages of tiiese materials
include: 1) Uie variety of compounds avaUable, 2) sheeting is produced in a factory environment, 3) polymeric
membranes are flexible, and 4) simple instaUation. Thc disadvantages include: 1) chemical resistance must be
detennined for each appUcation, 2) seaming systems may be a weak Unk in die system, and 3) many materials
are subject to attack from biotic, mechanical or environmental sources.
GeotextUes are uncoated synthetic textUe products dial are not water tight They arc composed of a variety of
materi.nl«t, most ccKumonly polypropylene and polyester. Geotextiles serve five basic functions: 1) fUtration, 2)
drainage, 3) separation, 4) reinforcement and 5) armoring.
FOT more infonnatton on geosyntiietics, see Uic reference below.
REFERENCES
Covers for UnconttoUed Hazanlous Waste Sites, USEPA EPA/54(V2-85/002, PB87-119483, 1985.
Industrial Handbook 4 - 36 March, 1993
ACTIV ITY: BUILDING AND GROUNDS MAINTENANCE
Graphic: North Cwitral Texas COG, 1993
Applications
Manufacturing
Material Handling
Vehhie Maintenance
Construction
C^nwnefcta/ /ictivities^
^Roadways^
Waste Containment
C^ousekeeplng Practices^
DESCRIPTION
Prevent or reduce tiic (Uscbargc of poUutants to storm water from buUdings and grounds
maintenance by washing and cleaning up with as Uttle water as possible, preventing and
cleaning up spills immediately, keeping debris from entering tbe storm dnuns, and
maintaining tbe storm water collection system.
APPROACH
• Leaving or planting native vegetation to reduce water, fertiUzer, and pestidde needs.
• Careful use of pestiddes and fertUizers in landscaping.
• Integrated pest management where appropriate.
• Sweeping of paved surfaces.
• CHeaning of the storm drainage system al appropriate intervals.
• Proper disposal of wash water, sweepings, and sediments.
• For a quick reference on disposal alternatives for spedfic wastes sec Table 4.1, SC 1.
REQUIRMENTS
• Costs (Capital O&M)
Cost wiU vary depending on die type and size of faciUty.
OveraU costs should be low in comparison to oUier BMPs.
Maintenance
The BMPs themselves rekite to maintenance and do not require maintenance as
they do not involve sttuctures.
LIMITATIONS
• Alternative pcst/wced controls may not be available, suitable, or effective in every
case.
Targeted Constituents
# Sediment
# Nutrients
# Heavy Metals
0 Toxh Materials
9 Fhatable Materials
9 Oxygen Demand-
ing Substances
# Oil & Grease
O Bacteria & Viruses
W Ukely to Have
Significant Impact
O Probable Low or Unknown Impact
Implementation
Requirements
O Capital Costs
Q O&M Costs
O Maintenance
O Training
• High O Low
SC11
Best'
Management
Practices^
Industrial Handbook 4-37 March, 1993
Additional Information — Building and Grounds Maintenance
BuUdings and grounds maintenance includes taking care of landscaped areas around tbe fadUly, cleaning of paiking lots
and pavement other than in tiie area of industrial activity, and die deaning of Uie storm drainage system. Painting and
other nunOT OT majOT repairs of buUdings is covered in SC12 (Building Repair, Remodeling, and Constraction). Ceitain
nonnai maintenance activities can generate materials Uiat must be properly disposed. Other maintenance activities can
enhance water quality if Uiey are carried out more Crequentiy and/or in a more deUlierate fashion.
Pestidde/Ferti1i7er Management
Landscape maintenance involves the use of pesticides and fertUizers. Proper use of tiiese materials wUl reduce the risk
of loss to Storm water. In particular, do not apply Uiesc inaterials during the wet season as Uiey may be canied from tiie
site by the next storm. Wben irrigating the landscaped areas, avoid over-watering not only to conserve water but to
avoid thc discharge of water which may have become contaminated wiUi nutrients and pestiddes.
It is important to properly store pestiddes and appUcation equipment and to dispose Uie used containers in a responsible
manner, consistent witii state regulattons. Personnd who use pestkidcs should be ttained in Uieir use. Tbe CaUfornia
Department of Pestidde RegiUation and county agriculttiral commissioners Ucense pestidde dealers, certify pestidde
applicators, and conduct on-site inspections.
Written procedures for the use of pesticides and fertilizers relevani to your facUity would help maintenance suiff under-
stand tiic "do's" and "don'ts". If you have large vegetated areas, consider the use of integrated pest management (IPM)
techniques to reduce the use of pesticides.
Paildng/Stonn Sewer Maintenance
A parking area that drains to the same storm drainage system as Uie industtial activity Uiat is to be pennitted must also be
evaluated for suitable BMPs. Storm water from parking lots may contain undesirable concentrations of oil grease,
suspended particulates, and metals such as copper, cadmium, and zinc, as weU as tiie petroleum byproducts of
engine combustion. Deposition of air particulates, generated by tbe facUity or by adjacent industries, may contribute
significant amounts of poUutants.
Tbe two most appropriate maintenance BMPs are periodic sweeping and cleaning catch basins if they are part of die
drainage system. A vacuum sweeper is die best mediod of sweeping, ratiier tban mechanical brush sweeping which is
not as effective at removing tbe fme particulates.
Caleb basins in paricing lots generaUy need to lie deaned every 6 to 12 months, or whenever the sump is half fuU. A
sump tiiat is more Uian half fuU is not effective at removing additional particulate poUutants from tbe storm water. If the
Stonn drain lines have a low gradient less Uian about 0.5 fea in elevation drop per 100 feel of Une. il is Ukdy that
material is settiing in the lines during tbe small frequent stonns. If you have nol cleaned tiic storm drain system for
some time, check Uic Unes as wclL If they are not cleaned, die catch basins wiU lUcely be filled during tiic next signifi-
cant storm by material that is washed from the Unes. Also, insuUl "uim-down" elbows or similar devices on Uic outiets
of tbe cau:h basins; they serve to retain floatables, oU and grease.
CHearly mark tiie stoim drain inlets, either wiUi a COIOT code (to distinguish from process water inlets if you have them)
OT wiUi die painted stencU of "DO NOT DUMP WASTE". Tbis wUl minunize inadvertent dumping of Uquid wastes.
Sweepings and sediments from tiiese maintenance activities are generally low in mettUs and otiier pollutants and tiiere-
fore can be disposed on-site OT to a consttuction debris landfUL Test Uie malerial if there is a reasonable doubt whelher
metals or other pollutants are present If concentrations of contaminants are high, it indicates that otiier BMPs may be
needed to eliminate OT reduce emissions from die source. If a vactor ttuck is used to clean die stoim drainage system.
Industriai Handbook 4-38 March, 1993
Additional Information — Buiidmg and Grounds Maintenance
dirty water wiU be generated. This water should not be discharged to die suxm drainage system as it is silt laden and
contams much of tiic poUutants dial were removed by die catch basins. The water should be disposed to die process
wastewater system, if you have one, OT to die pubUc sewer if pennission is granted by die local scwcr autiiority. Alterna-
tively, thc water can lie placed somewhere on thc site where it can evaporate.
The cleaning of tiie paved surfaces and catcb basins in die areas of industtial activity has been discussed previously in
SC5 (Loading and Unloading of Materials), SC7 (Outdoor Process Equipment Operations and Maintenance), and SCS
(OutdoOT Storage of Raw Materials, Products, and Byproducts).
If some employees have cars dial are leaking abnoimal amounts of engine fluids, encourage tiiem to have die problem
corrected.
Examples of Effective Proorams
Infomation on integrated pest management may be obtained from die Bio-Integral Resource Center, P.O. Box 7414,
Bcriceley, CA 94707,510-524-2467.
REFERENCES
Best Management Practices for Industtial Storm Water PoUution Conttol Santa Clara VaUcy Nonpoint Source Pollution
Conttol Program, 1992.
Industrial Handtxiok 4-39 March, 1993
ACTIVITY: BUILDING REPAIR, REMODEUNG AND CONSTRUCTION
Graphic: North Central Texas COG, 1993
Applications
Manufacturing
Material Handling
Vehicle Maintenance
(^Onstruction^
(^Commercial Activh^^
Roadways
Waste Containment
(housekeeping Practic^^
DESCRIPTION
Prevent or reduce thc discharge of poUutants to stoim water from buUding repair, remodel-
ing, and constraction by using soU erosion conttols, endosing or covering buUding
material storage areas, using good housekeeping practices, using safer alternative prod-
ucts, and training employees.
APPROACH
Use soU erosion conuol techniques if bare ground is temporarUy exposed. See die
Consttuction Activity Best Management Practice Handbodc.
• Use permanent soU erosion conuol techniques if die remodeUng clears buildings from
an area dial are not to be replaced. See SClO (Contaminted OT Erodible Surface
Areas).
• Enctose painting operations, consistent witii local air quality regulations and OSHA.
• Property store materials that are normally used in repair and remodeling sucb as
paints and solvents.
• Properly store and dbpose waste materials generated from die activity. Sec CA20,
SoUd Waste Management Constraction Handbook.
• Maintain good housekeeping practices whUe woric is underway.
REQUIREMENTS
• Costs (Coital O&M)
These BMPs are generaUy of low to modest in cost
LIMITATIONS
• Tbis BMP is for minor constraction only. Thc State's General Consttuction Activity
Stonn Water Permil has more requirements fOT larger projects. The companion
"Constraction Activity Best Management Practice Handbook" contains spedfic
guidance and best management practices for larger-scale projects.
• Hazardous waste that cannoi be re-used or recycled musl be disposed of by a Ucensed
hazardous waste hauler.
• Safer alternative products may not be avaUable, suitable, or effective in every case.
• Be cenain tbat actions to help storm water quality are consistent widi Cal- and Fed-
OSHA and air quality regulations.
Modifications are a common occurrence particularly at large industtial sites. The activity
Targeted Constituents
# Sediment
O Nutrients
% Heavy Metals
% Toxh Materials
9 Floatable Materials
O Oxygen Demand-
ing Substances
# 0/7 & Grease
O Bacteria & Viruses
• Ukely to Have
Significant Impact
O Probable Lour or
Unknown Impact
Implementation
Requirements
O Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
SC12
Best^
Management
P^actices^
Industrial Handbook 4 • 40 March, 1993
Additionai Information — Building Repair, Remodeling, and Construction
may vary from minor and normal buUding repair to major remodding, or thc installation of new fadUties on cunentiy
open space. These activities can generate pollutants dial can reach storm water if proper care is not taken. The sources of
tiiese contaminants may be solvents, paints, paint and vamish removers, finishing residues, spent thinners, soap cleaners,
kerosene, asphalt and concrete materials, adhesive residues, and old asbestos installation.
Good Hon5;ekeeping
Proper care involves a variety of mostiy common sense, housekeeping actions sucb as:
• Keep the woric site clean and orderiy. Removing debris in a timely fashion. Sweep the area.
• Cover materials of particular concern tiiat musl be lefl out particulariy during die rainy season.
• Educate employees who are ctoing the woric.
• Infonn on-site contiactors of company poUcy on these matters and include appropriate provisions in their contract to
make certain proper housekeeping and disposal practices are implemented.
• Make sure that nearby storm drains are wcU marired to minimize the chance of inadvenent disposal of residual
paints and other Uqiuds.
• Do UOT dump waste Uquids down the storm drain.
• Advise concrete track drivers to not wash Uicir track over thc storm drain. Have a designated area that docs not
drain to die storm drain.
• Clean die stoim drain system in the immecUate vidnity of tbe constraction activity after it is completed.
Proper education of off-site contractors is often overlooked. Thc consdentious efforts of weU tiained employees can be
lost by unknowing off-site contractors, so make sure they are weU infoimed about what they are expected to do.
Painting operations should be properiy enclosed or covered to avoid drift Use temporary scaffolding to bang drop clotiis
OT draperies to prevent drift Application equipment that minimizes ovcispray also helps. Local air poUution regulations
may, in many areas of tiie state, specify painting procedures whidi if properiy canied oul are usuaUy suffident to protea
water quality. If painting requires scraping or sand blasting of die existing surface, use a ground ctotii to coUea Uic
chips. Dispose tbe residue properly. If die paint contains lead or bibutyl tin, it is considered a hazardous waste.
Mix paint indoors before using so that any spUl wiU nol be exposed to rain. Do so even during dry weatiier because
ck^up of a spUl wiU never be 100% effective. Dried paint wiU erode from a surface and be washed away by storms. If
using water based paints, clean tiic s^Ucation equipment in a sink tbat is connected to die sanitary scwcr. Properly store
leftover paints if Uiey are to be kept for the next job, OT dispose properly.
Wben using sealants on wood, pavement, roofs, eU:, quickly clean up spUls. Remove excess UqukJ wth absorbent
material OT rags. If wbcn repairing roofs, smaU particles have accumulated in tiae gutter, dUicr sweep oul tiie gutter or
wash thc gutter and trap tbe panicles at thc outiet of tiic downspout A sock OT geofabric placed over tbe outlet may
effectively trap die materials. If tbe downspout is tight lined, place a temporary plug at the first convenient point in tbe
stoim drain and pump oul the water wiUi a vaaw track, and clean die cateh basin sump where you placed die plug.
Soil/Erosion Cnntml
If tiie work involves exposing large areas of soU employ tiie apprc^riate soil erosion and conttol techniques. See tiie
Constraction Best Managemeni Practice Handbook. If old buUdings are being tom down and not replaced in die near
fiittire, StabUize die site using measures described in SClO, Contaminated or Erodible Surface Areas.
If a buUding is to be placed over an open area witii a storm drainage system, nuUce sure die sttxm inlets widiin Uic
Industrial Handbook 4-41 March, 1993
Additional Information — Buiiding Repair, Remodeling, and Construction
iHiUding are covered or removed, OT the storm line is connected to thc sanitary sewer. If because of tbe remodeUng a
new drainage system is to be instaUed or thc existing system is to be modified, consider instaUing catch basins as they
serve as effective "in-Une" tteatment devices. Sec TC2 (Wet Ponds) in Chapter 5 regarding design criteria. Include in
the catch basin a "turn-down" elbow OT similar device to trap floarables.
Recyde residual paints, solvents, lumber, and other materials to die maximum extent practical. Buy recyded products
to the maximinn extent practical.
REFERENCES
Best Management Practices for Industtial Storm Water PoUution Conttol Santa Clara VaUey Nonpoint Source PoUution
Control Program, 1991
Industrial Handbook 4 • 42 March, 1993
ACTIVITY: OVER-WATER ACTIVITIES
vMTcn.naHT
msn OMTAIMCil
FonnauDtKesra
Applications
Manufacturing
C[^fer*a/ Handling^
Vehhie Maintenance
Construction
^Commercial Activiti^^
Roadways
Vaste Containment^
housekeeping Practic^.
DESCRIPTION
Prevent or reduce the discharge of poUutants to storm water and receiving waters from
over-water activities by minimizing over-water maintenance, keeping wastes oul of the
water, cleaning up spiUs and wastes immediately, and educating tenants and employees.
APPROACH
Properly dispose of domestic wastewater and ballast water.
Lunit over-water huU surface maintenance to sanding and minor painting.
Use phosphate-free and bicxlegradable detergents for huU washing.
Use secondary containment on paint cans.
Have available spiU containment and cleanup materials.
Use ground cIoUis wbcn painting boats on land.
Use tarps, pbstic sheeting, etc. to contain spray paint and blasting sand.
Properly dispose of surface chips, used blasting sand, residual paints, and other
materials. Use temporary storage containment that is not exposed to tain.
Immediately clean up spills on dodcs OT boats.
Sweep diydodcs before flooding.
Clean catch basins and the stoim drains at regular intervals.
Post signs to indicate proper use and disposal of residual paints, rags, used oil and
other engine fluids.
Educate tenants and employees on spiU prevention and cleanup.
Include appropriate language in tenant contracts indicating dieir responsibUities.
Marinas should provide wastewater dbposal faciUties.
REQUIREMENTS
• Cost (Capilai, O&M)
Most of thc BMPs are of low and modest cost Exceptions are stations for
temporary storage of residual paints and engine fluids, and wastewater pumpout
faciUties.
• Maintenance
Keep ample supply of spiU cleanup materials.
LIMITATIONS
Private tenants at marinas may resist restrictions on shipboard painting and maintenance.
Existing contracts witb tenants may not allow the owner to require that tenants abide by
new rales that benefit water quality. Even biodegradable cleanmg agents have been found
to be toxic to fish.
Targeted Constituents
O Sediment
O Nutrients
9 Heavy Metals
9 Toxh Materials
9 Floatable Materials
0 Oxygen Demand-
ing Substances
# Oil & Grease
# Bacteria & Viruses
# Ukely to Have
Significant Impact
O Probable IJ»W or Unknown Impact
implementation
Requirements
O Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
SC13
Best^
Management
Practices^
Industrial Handbook 4-43 March, 1993
Additional Information — Over-Water Activities
Over-water activities cxxur at boat and ship repair yards, marinas, and yacht clubs, altiiough the later are not required to
obtain a permit Activities of concern indude chipping and painting of hulls, on board maintenance of engines, and tbe
disposal of domestic wastewater and baUasl water. Witii few exceptions, BMPs to protect water quaUty arc common
sense, low cost changes to normal day-to-day procedures.
Over-water Activitv Minimization
Work on boats in thc water should be kept to a minimum. Major hull resurfadng should occur on land. Surface prepara-
tion over water should be limited to sanding. Painting should be limited to spot work. In marinas, tenant maintenance
over water should be sucb as to not require opening more tiian a pint size paint can. Paint mixing should not occur on
die dock.
Good Housekeeping «
Wben conducting on board maintenance, used antifreeze should be stored in a separate, labeled drum and recycled. Fuel
tank vents should have valves to prevent fud overflows OT spills. Boats wiUi inboard engines should have oU absorptton
pads in bUge areas and they should be changed wtien no longer useful OT at least once a year.
Marina owners should provide temporary storage stations fOT usal engine fluids, paint cans, and other maintenance
materials. Signs shouki be posted at tbe bead of each dock indicating maintenance rales. Marina owneis should instaU a
wastewater disposal system, eitiier docksidc lines or a pumpout station. Tenant conuacts should include language
indicating their responsibiUties.
Wbcn painting on shore, place paint cans in a tray OT comparable device Uiat coUects spills and drips. Use ground cloths
when painting. Use spray guns tiiat minimize overspray; also CIKIOSC die area with plastic tarps. Identify a designaled
area fOT washing boats. Vacuum sweep woric areas frequendy. Wbcn doing repaiis OT painting on a tidal grid OT similar
open "dry dock", use ground cloths to retain chips and spilled paint The repair yard owner should instaU signs so dial
IxMt owners who are doing their own woik know Uieir responsibiUties.
Large boat repair yards can implement the above BMPs. There are several additional measures. Witb regard to dry dock
operations: sweep the accessible areas of tbe dry dock before flooding; and pidc up other debris dial appears after the
ship is floated. Remove floatable debris sucb as wood. Shipboard cooling and process water discbarges should be
directed to minimize contaa with spent abrasives, paints, and other debris. Look for and repair leaking valves, pipes,
hoses, or soU chutes carrying cither water OT wastewater. Pkistic sheeting or other suittible materials should be instaUed
wben sandblasting and spray painting.
Use drip pans or comparable devices when tt:ansferring oils, solvents, and paints. Regularly clean tiie shoresidc work
areas of debris, sandblasting material, etc Clean catcb basins orother parts of tiie storm drauiage system dial might
accumulate these materials.
Fish Waste
Fish wastes must also be managed properly. RecycUng fish wastes bade to the water is encouraged wben disposal wiU
not result in water quaUty OT public nuisance problems, such as wastes washing up onshore OT causing odors or bacteria
problems. Fish wastes shouki not be recycled in any dead end lagoons or other poorly flushed areas. Marina owners
shouki provkie fish cleaiung stations where waste recycling can occur witiiout adversely affecting water quaUty.
Note: San Francisco Bay Area boat repair and maintenance faciUties. Thc San Francisco Bay Regional Water Quality
Conttol Board bas issued a General Storm Water NPDES Pennit to boat yards which work primarily on pleasure vessels
less tban 65 feet in length. Thc General Permil requires maintenance of pressure wash containment and recycle or
prctteattncni system implemenuition of a Stotm Water PoUution Control Plan (SPCP) and a Monitoring Program.
Industrial Handbook 4-44 March, 1993
Additional Information — over-water Activities
REFERENCES
Proposed Guidance Specifying Management Measures for Sources of Nonpoint PoUutton in Coastal Waters, USEPA,
1992.
General NPDES Pennit for Discharges of Sttxm Water from Boat Repair Fadlities, SFBRWQCB, 1992.
Industrial Handbook 4-45 March, 1993
ACTIVITY: EMPLOYEE TRAINING Applications
(I^^^^ManufacturingJI^
"Material Handlinc
Vehhie Maintenance
Construction
(^Commercial Activities^
Roadways
Vaste Containment
^usekeeping Practices,
DESCRIPTION
Emptoyee training, Uke equipment maintenance, is not so much a best management practice as it is a method by which to
implement BMPs. This fad sheet highUghts the nnportance of ttaining and of mtegrating die elements of employee
ttaining from the individual source controls into a comprehensive training program as part of a faciUty's Storm Water
PoUution EYevcntion Plan (SWPPP).
Thc spedfic employee training aspects of each of the source controis are highlighted in the individual fact sheets. The
focus of diis faa sheet is more general and includes the overaU objectives and approach for assuring employee training
in storm water poUution prevention. AccOTdingly, tbe OTganization of diis faa sheet differs somewhat from die other faa
sheets in this chapiter.
OBJECnVES
Employee training should be based on four objectives:
• Pnxnote a clear identification and understanding of thc problem, including activities with tbe potential to pollute
stram water;
Identify solutions (BMPs);
• Promote employee ownership of tbe problems and die solutions; and
• Integrate employee feedback into training and BMP implementation.
APPROACH
• Integrate ttaining regarding storm water quality management with existing training programs tiiat may be required
for your business by otiier regulations such as: the fllness and Injury Prevention Program (HPP) (SB 198) (Califomia
Code of Regulations Titie 8, Sectton 3203), tbe Hazardous Waste Operations and Emergency Response
(HA2WOPER) standard (29 CFR 1910.120), tiic SpUl Prevention Conttol and Countermeasure (SPCQ Plan (40
CFR 112), and the Hazardous Materials Managemeni Plan (Business Plan) (California Healdi and Safely Code,
Section 6.95).
• Businesses, particiUarly smaUer ones dial are not regulated by Federal, State, or local regulations, may use tbe
information in this Handbook to develop a training program to reduce dieir potential to poUute storm water.
LISTING OF INDUSTRLVL ACTrVTTIES
Employee ttaining is a vital component of many of die individual source control BMPs included in diis chapter. Follow-
ing is a compilation of tbe ttaining aspects of die source control fact sheets.
Indu.strial Hundliook 4 - 46 March, 1993
ACTIVITY — EMPLOYEE TRAINING (Continue)
SCI Non-Storm Water Discharges to Drains
• Use the quick reference on disposal altematives (Table 4.1) to train employees in proper and consistent methods
fOT disposal.
Consider posting tbe quick reference table near storm drains to reinforce ttaining.
SC2 Vehkle and Equipment Fueling
• Train employees in proper fuding and cleanup procedures.
Thc SPCC Pkm may be an effective program to reduce die number of acddental spills from fueling.
SC3 VehKle and Equipment Washing and Steam Cleaning
• Train employees in sttmdard operating procedures and spUl cleanup techniques described in the faa sheet
SC4 Vehicle and Equipment Maintenance and Repair
• Train employees in standard operating procedures and spiU cleanup techniques described in die faa sheet
• Paint stencils to remind employees not to pour waste down storm drains.
SCS Outdoor LoadingiTJnloading of Materials
• Use a written operations pian tbat descrities procedures fOT loading aad/or unloading.
Have an emergency spiU cleanup plan readily avaUable.
• Employees tiained in spUl containment and cleanup should be present during loading/unloading.
• Make sure foik Uft operators are also properly trained.
SC6 Outdoor Container Storage of Liquids
• Registered and specifically trained professional engineeis can identify and conect potential problems such as
loose fittings, poor welding, and improper OT pooriy fitted gaslcets fOT newly instaUed tank systems.
• Emptoyees trained in emergency spiU deanup procedures should be present wbcn dangerous waste, liquid
chemicals, or other wastes are bandied.
SC7 Outdoor Process Equipment Operations and Maintenance
• Thc prefened and possibly most economical action to reduce storm water poUution is to alter the activity. This
may mean ttaining employees to perform tbe activity during dry periods only or substittiting beiugn materials
fOT more toxic ones.
SCS Outdoor Storage of Raw Materials, Products, and By-Products
• Train employees in standard operating procedures and spUl cleanup techniques described in the faa sheet
SC9 Waste Handling and Disposal
• Train employees in standard operating procedures and spiU cleanup tedmiques described in the faa sheet
• Paint stencils to remind employees not to pour waste down storm drains.
SClO Contaminated or Erodible Surface Areas
• Training is not a significant clement of diis best management practice.
Industriai Handbook 4-47 March, 1993
ACTIVITY — EMPLOYEE TRAINING (Continue)
SCll Building and Grounds Maintenance
• Persoimel who use pestiddes should be ttained in dieir use. The (Talifoniia Department of Pestidde Regulation
and counly agricultural commissioners Ucense pestidde dealers, certify pestidde appUcators, and condua on-
site inspections.
• Written procedures for die use of pestiddes and fertilizers relevant to your faciUty would help maintenance staff
understand the "do's" and "don'ts". If you have large vegetated areas, consider the use of integrated pest
management (IPM) tedmiques to reduce die use of pestiddes.
SC12 Building Repair, RemodeUng, and Construction
• Proper education of off-site contractors is often overlooked. The consdentious efforts of wcU ttained emptoyees
can be lost by unknowing off-site conttacuxs, so make sure tiiey are wcU infoimed aboul what ihey are ex-
pected to do.
t
SC13 Over-Water Activities
• Post signs to indicate proper use and disposal of residual paints, rags, used oU, and other engine fluids.
• Educate tenants and employees on SIHU prevention and deanup.
• Indude appropriate language in tenant conuacts indicating their responsibUities.
Industriai Handbook 4 -4« March, 1993
APPENDIX 7
INDUSTRIAL / MUNICIPAL STORM WATER TREATMENT
CONTROLS
5. TREATMENT CONTROL BMPs
INTRODUCTION
This ciiapter
describes
specific
MMwH^MHi^H^Hi treatment
control Best
Management Practices (BMPs) for removing
pollutants in storm water from industrial
fadlities.
Each fact sheet contains a cover sheet with:
4
A description of the BMP
• Suitable AppUcations
• Installation/Application Criteria
• Requireihents
Costs, including capital costs, and
operations and maintenance (O&M)
Maintenance (including
administrative and staffing)
• Limitations
The side bar presents information on which
BMP considerations, targeted constituents, and
an indication of the level of effort and costs to
implement The remainder of the fact sheet
provides further information on some of all of
these topics, and provides references for
additional guideUnes.
BMP fact sheets are provided for each of the
following controls:
Treatment Control BMPs
TCI Infilttation
TCI Wet Ponds
TC3 Consttucted Wetiands
TC4 Biofiiters
TC5 Extended Detention Basins
TC6 Media FUttation
TC7 Oil/Water Separators and Water
Quality Inlets
TC8 MulUple Systems
GENERAL
PRINQPLES
control BMPs.
There are
several general
principles that
are applicable to
all treatment
Priority should be given to source
control: Source control BMPs are
generally (but not always) less expensive
tiian freatment control BMPs. Also,
treatment confrol BMPs will not remove
aU pollutants and tiieir removal efficiency
is difficult to predict given the limited
understanding as to tiie relationship
between facility design criteria and
performance.
Recognize the unique California
cUmate: With few exceptions most
storm water treatment experience has been
in "wet" states where vegetation can be
maintained without irrigation. In confrast,
Califomia's climate is semi-arid with the
exception of the north coast. The
freatment confrol BMPs Uiat require
vegetative cover may not be practical for
many areas of California unless irrigation
is provided. Also, design criteria have
emerged from research of faciUties located
in climates where the rainfall season is
coincident with the growth of vegetation.
However, in California, tiie wet season
does not occur during the primary growth
season. Caution must be used in using
design criteria that have been developed
elsewhere in die nation.
Design Storm Size; It is commonly
thought by Uiose unfamiliar wiUi urban
runoff quality management Uiat design
stonns for sizing water quality controls
should be die same as tiiose used for tiie
design of drainage facilities. This is not
frue. The damage done to a receiving
water by die pollutant wash-off of a 25.
year storm (commonly used to size a
Industrial Handbook 5-1 March, 1993
drainage system) is inconsequential to tiie
potential hydraulic damage. Of concern
to water quality confrol are die small
frequent events, smaller tiian die 1-year
storm, that carry tiie vast majority of
runoff and pollutants. There is little or no
incremental benefit from sizing facilities
to freat the exfreme events.
Bare and erosive soils may affect
treatment control BMPs: Protection of
natural watercourses requires that
sediment fransport not be altered for the
watercourse. Therefore, consideration
must be given to fransport loads. In *
addition, many residential developments in
Califonua have open space areas covered
by native vegetation. Because of die
semi-arid climate, die vegetadon is titin
aUowing for erosion during severe storms.
These higher tiian normal sediment loads
may adversely impact tiie performance
and maintenance requirements of
freatment control BMPs.
Consider the characteristics of
poilutants in storm water: The presence
and concenfration of pollutants is highly
variable, botii witiun and between storms.
PoUutants come in two forms, particulate
and dissolved. Some freatment control
BMPs will only remove particulates.
Various vegetated BMPs such as wet
ponds are purported to remove dissolved
pollutants as well as particulates.
Vegetated freatment confrol BMPs have
mechanisms tiiat tiieoretically should also
remove botii forms, however, the data
confirming tiie tiieory are limited and
sometimes confradictory.
Incorporate multiple use objectives:
Oppormnities abound to integrate storm
water freatment needs witii otiier
management objectives such as die use of
wet ponds and consttucted wetiands for
passive recreation, wildlife habitat, flood
detention, and ground water recharge.
Maintenance is very important: AU of
the freatment confrol BMPs described in
Chapter 5 are passive systems, tiiat is,
tiiey operate witiiout tiie need for
mechanical or chemical systems.
Nonetiieless, maintenance is very
important for die facilities to operate
effectively.
Factors to Consider: Each fact sheet
lists seven general factors tiiat are tiie
most common considerations in selecting a
freatment control BMP. In every case, all
freatment confrol BMPs must be
compatible witii existing flood confrol
objectives.
Soil: Infilfration systems must be
located on suitable soils; vegetation
requires good soils; wet pond bottoms
require impermeable soils.
Area Required: Most BMPs require
considerable area, although some can
be placed underground.
Slope: Certain BMPs cannot be
placed on or near steep slopes as die
ponding of water or velocity of flow
may cause instability or excessive
erosion.
Water Availability: BMPs using
vegetation for pollutant removal may
require water during the dry season.
Aestiietics and safety: Where visible
or accessible to die public, aestiietics
or safety can be a concern witii some
BMPs.
Hydraulic Head: A few BMPs
require a drop in water elevation
which site topography may not
provide.
Environmental Side Effects:
Considerations for mosquito breeding,
ground water contamination, as well
as oppormnities for aquatic wildUfe
and passive recreation.
Industrial Handbook 5-2 March, 1993
BMP: INFILTRATION
Runoff
Considerations
'..Area Required^
,Slope
Water Availability
Aesthetics
Hydraulic Head
Environmental Side
\^..,Effecfs
DESCRIPTION
A famUy of systems in which the majority of the runoff from smaU storms is infiltrated into
die ground rather than discharged to a surface water body. Infiltration systems include:
ponds, vaults, trenches, dry wells, porous pavement and concrete grids.
EXPERIENCE IN CALIFORNIA
InfUttation ponds have been used by many local jurisdictions and CalTrans in die Central
VaUey for aboul Uiree decades.
SELECTION CRITERU
Need to achieve high level of particulate and dissolved pollutant removal.
Suitable site soils and geologic conditions; low potential for long-term erosion in die
watershed.
• Multiple management objectives (eg., ground water recharge or ranoff volume
conttol).
LIMITATIONS
• Loss of infUttativc capadty and high maintenance cost in fme soUs.
• Low removal of dissolved poUulants in very coarse soUs.
Not suitable on fiU sites or steep slopes.
Risk of ground water contamination in very coarse soils, may require ground water
monitoring.
• Should not use untU upstream drainage area is stabUized.
• InfUttation facUities could fall under Chapter 15, Tide 23, of Califomia Code of
Regulattons regarding waste disposal to land.
DESIGN AND SIZING CONSIDERATIONS
Volume sized to capture a particular fraction of annual ranoff.
Pretteatmcnl in fine soils.
Emergency overflow or bypass for larger stonns.
Observation weU in trenches.
CONSTRUCTION/INSPECTION CONSIDERATIONS
Protea infUtration surface during constraction.
Vegetation of pond sides to prevent erosion.
Frequent inspection fOT clogging during constraction.
Targeted Constituents
9 Sediment
O Nutrients
9 Heavy Metals
% Toxic Materials
% Floatable Materials
9 Oxygen Demand-
ing Substances
# Oil & Grease
# Bacteria & Viruses
W Ukely to Have
Significant Impact
o Probable Low or Unknown Impact
Implementation
Requirements
O Capital Costs
Q O^AT Costs
O Maintenance
O Training
High O Low
TC1
Best^
Management
Practices>
Industrial Handbook 5-3 March, 1993
Industrial Handbook 5-4 March, 1993
Additional Information — Infiltration
General Informalion
Where conditions are suitable infilu-ation systems may be die preferred choice because storm water is placed into the
ground thereby redudng excess ranoff and providing groundwater recharge.
InfUtration systems include:
• InfUttation basin which is an open surface pond or underground vault (Figure lA)
• InfUttation trench which is an underground chamber filled with rock, also called a rock weU (Figure IB).
• Dry weU or "vertical" infiltration trench (Figure IC)
• Porous pavement both asphalt and concrete (Figure ID).
Concrete grid and modular pavement which are latuce grid stractures with grassed, pervious material placed in the
openings (Figure IE).
i
Inflltration basins are generally used for areas less dian five acres but can handle ttibutary areas up to 50 aaes if die soil
is very permeable. Tbe other systems are suitable only for small sites of a few acres. Porous pavement and concrete
grids should only be. used in low ttaffic areas lUce paiking areas. Smdies have shown that porous pavement is sttong and
wiU last as tong as conventional pavement (Field, et al 1982; Gburek and Urban. 1980). Experience in Florida and
Maiyland indicates tbat concrete porous pavement performs better dian porous asphalt Porous pavements and under-
ground fadlities may be favored at industrial sites where land is already needed for business activities.
InfUtration systems should be considered where dissolved pollutants are of concem. However, satisfactory removal
effidencies require soils tbat contain loam. Coarse soUs are not effecuve at removing dissolved poUutants and fine
particulates before die storm water reaches the ground water aquifer.
Local jurisdictions may not feel that infUtration systems are appropriate on industrial sites where spills of hazardous
chemicals can occur. However, spUl control procedures may provide satisfaaory control (Chapter 4). Care should be
ttiken when considering tbe multiple objectives of using inflltration systems for water quality tteatment ground water
recharge, and flood control Inflltration basins, uenches, and porous pavement can meet storm water detention require-
ments.
Three concerns with infUttation systems are clogging, accumulation of metals, and ground water contamination.
InfUttation systems have been used successfully on sandy soils in die Central VaUey of California and Long Island, New
York for many years widiout operational problems. In bodi instances die primary objectives are ground water recharge
and flood control, not water quaUty tteatment
Problems can be expected with infiltration systems placed in fmer soils. The State of Maryland has emphasized diese
systems for about 10 years where tliey bave been installed in soUs with infiltration rates as low as 0.27 inches per hour.
A recent survey (Lindsey, et al., 1991) found dial a diird of the fadlities examined (177) were clogged and anotiier 18%
were experiendng slow infUttation. Dry wells diat tteat roof ranoff had die fewest failures (4%) and porous pavement
the most (77%). Dry wells may have die lowest CaUure rate because they only handle roof ranoff. The primary causes
of failure appear to be inadequate prctteaoneni and lack of soU stabUization in die ttibutary watershed, as well as poor
construction practices (Shaver, pers. comm.). Erosion of die slopes of infUttation ponds was a significant problem in
ahnost half die fadUties surveyed. Problems have occurred in die Central VaUey with facUities pkiced on finer soils, as
in die case of Modesto. (Tultocb, pers. comm.).
Based on a review of several smdies of infiltration fadlities in sandy and loamy soils concluded diat "monitoring ... has
nOT demonstrated significant contamination... aldiougb highly soluble poUuttuits such as ninate and chloride have been
shown to migrate to ground water" (USEPA, 1991). However, poUution bas been found in ground water where infUtta-
tion devices are in coarse gravels (Adophson, 1989; MUler, 1987).
Industrial Handbook 5 - 5 March, 1993
Additional Information — Infiltration
Site Selection Con.sidpratinn^j (infUttation basin)
• Reconunended minimum preconsttuction infUttation rates have ranged from 0.25 to 4 inches per hour.
• One suite (Ecology, 1992) has specified a maximum clay content (30%) and a minimum cation cxcbanae capadty (5mcq). =» 7
• Not less dian Uuee feet separation from seasonal high ground water, much greater distance if soils are very coarse.
• Avoid steep (25%) slopes or otiier geologic conditions diat would be made unstable by die infUuating water.
• Not less dian four feet separation from bedrock.
Impaa on local groundwater including recharge potential water quality, etc.
Stahre and Urtionas (1988) have presented a site selection procedure, if die site fu^t passes die above criteria Presented
in Table lA is a point system. If die site receives less dian 20 points it is considered unsuiuible; more dian 30 points is
considered excellent This procedure is used tq enhance infilttation performance and minimize clogging.
Design
The degree of tteattncni achieved by infilttation is a function of die amount of storm water dial is captured and infU-
ttaUJd over time. This relationship fOT various areas in Califoraia is shown in Appendix D. The figures in Appendix D
were developed using die hydrological model STORM.
The procedure to detennine die volume of infilttation basin is as foltows: (1) select die appropriate figure in Appendix
D; (2) deUOTune for die catchment die percenuigc of impervious area directiy connected to tiie storm drain system; (3)
choose a capttttc goal, and read die required unU basin storage (aae-ft per acre) required for die infilttation basin (to
provide perfonnance simUar to die odier tteattncni conttol BMPs in Chapter 5, a reasonable capture goal for infUttation
systems is 80%.); (4) multiply diis unil figure times die total acreage of die catchment and convert to cubic feet When
usmg die above approach to size an infilttation ttench, remember to increase die volume of die ttench to account for die
rode.
To calculate tiic mimmum surface area of die infUttation system obtain die infiltration rate at die site using appropriate
techniques. Thb value is dicn used in die foUowing equations:
^m = V/D 'm (1)
where: A^
V
D, m
= minunum area required (ft^)
= volume of the infUttation basin (ft^)
= maximum allowable basin depth (ft)
Thc maximum allowable depth is determined from die equation:
Dm = 40I/12S (2)
where: I = site infilttation rate in inches per hour
S = safety faaOT
Thc safety faciOT accounts for die uncertainty of whedicr die infilttation test measures die real infilttation rate Recom-
mendations have ranged from 2 to 10 (consult your local SoU Conservation Service Office). Tbe coeffident of 40
refers to tiic recommended drawdown time in hours. TTiis is a reasonable drawdown time, given diat die average time
between storms during tiic wel season in CaUfomia is on die onler of 200 hours, except in Northern Califoraia where it
IS about 80 hours. A tonger drawdown time may cause anaerobic conditions in die underlying soil OT die production of
algae dunng die wanner mondis dial would clog die soU. A shorter drawdown time reduces die volume of die fadlity
but mcreases die required surface area. Appendix D conlains figures for two drawdown times: 24 and 40 hours. In
most of die Suite, reducing die drawdown time does not significantiy reduce die volume.
Industrial Handbook 5-6 March, 1993
Additional Information — Infiltration
Suggested references on the design of porous pavement include Maryland (1984) and Florida (1988).
Additional design cnnsidemtions
For basins and ttenches, prctteat die storm water to remove die floatables and settieable soUds, particulariy when
pladng diese systems in finer soils. Pretteatment can be accomplished with any of the other treatment control
BMI^ in this handbook.
Communities and CalTrans have used infiltration systems in die Central VaUey for more than two decades widiout
pretreatment Clogging bas not been a problem widi well maintained systems discharging to sands and courser soils,
suggesting dial preueattnent is of limited value. Pretteatmcnt when infiltrating to finer soUs is suggested by die
experience of Maryland described previously. An infilttation fadlity sized only for tteatment is much smaUer than one
sized for flood conttol and tiierefore may be more susceptible to clogging. Communities in die Central Valley (Fresno,
Modesto) require a retention volume that captures die 100 year event or about 20,000 ft^ per impervious tributary acre.
In comparison, above Equation (1) wiU provide a volume in the range of 2,000 ft^ per impervious acre.
For small systems treating less than a few acres of pavement pretreatment can be accompUshed witb a Type 2 catch
basin and a subperged oudet The diameter and depth of the sump should be at least four times the diameter of tbe
outiet pipe to die infilttation system (Lager, et al., 1977). See Figure IC. The catch basin cover should be stendled
"dump no waste". Vegetated biofiiters can also be used aldiough they wUl not IDcely be feasible in industtial sites
which tend to t>e fuUy utilized.
Additional design considerauons for ba.sins include:
• Do not locate on fdl sites, or on or near steep slopes
• Energy dissipation at inlet to minimize erosion
Vegetate thc slopes for the same reason
• Vegetate tlic bottom to reduce tendency to clog widi fines
• Freeboard of 1 foot
• Side slopes of at least 3:1 for safety, and for case of mowing (4:1 slopes are prefered)
• Incorporate bypass or overflow for large events
• Provide dedicated access to die basin bottom (minimum 4:1) for maintenance vehicles
Vegetating die slopes and bottom will be difficult unless die facUity can be irrigated during die summer. Drought
tolerant ground cover spedes may be more suitable. See TC4 Biofiiters for recommended species.
Additional design considerauons for trenches include:
• Do not locate on fill sites, or on or near steep slopes
A 4 inch or 6 inch diameter observation well with locking cap, to check for loss of infilttative capadty
• 6 inch sand layer or geofabric at the bottom
• Geofabric around ttench walls to prevent soils from migrating into the trench rock matrix
• Geofabric 12 inches below ground surface widi 3/4 rock placed on top, which serves as filter for coaise soUds
• BackfUl and filter rock should be clean washed aggregate 1 inch to 3 inches d'uimeter
• Incorporate bypass or overflow for large events
• Provide dedicated access for maintenance vehicles
For porous pavement, experience in Marykmd suggest dial asphalt pavement bas continuous plugging problems and a
limited Ufe. Frequent maintenance is required. For dryweUs where access for maintenance is difficult if not impossible
pretreatment of die storm water is highly recommended. Such prctteattncni may include biofilteis, sumps, etc. Consul-
tation widi die local jurisdiction regarding die design of dryweUs is required.
Industrial Handbook 5.7 March, 1993
Additional Information — Infiltration
Constnjaion
It is very important to protect tiie namral infUttation nue by using Ught equipment and consttuction procedures diat
nunimize compaction. Stonn water must not be allowed to enter die facility until all consttuction in die catehment area
is completed and die drainage area is stabiUzed. If diis prohibition is nol feasible in particuku- situations, do not excavate
die facUity to final grade until after all consttuction is complete upstteam. Leave one foot of native soU in die basin
which can be removed in layers as il dogs. Disking die surface frequendy during diis period may be benefidal After
final grading die fmal surface should also be disked. Widi ttenches, make sure die rock fiU does not become diny whUe
temporarily stored at die site.
The local jurisdiction may also specify dial die infUttation rate of die fadlity be widiin a certain percentage of die
preconstraction rate before tbe facUity is approved or accepted.
Maintenance <
Inspect die faciUty at least annually and after extreme events. If diere is stiU water in die pond or ttench 72 bours after a
stonn it is time to clean die fadlity. A concern is resttictions on die disposal of die sediment removed from an infiltta-
tion basin due to contamination. Lunited smdies suggest dial diis is not a problem, particularly if source-conttol BMPs
are effective. The Fresno McttopoUtan Flood Conttol Disttia found noticeable accumulation of poUuumts in Uie surface
layer in infUttation basins dial had nol been cleaned fOT about 20 years altiiough die levds were still below toxic duesh-
olds. The basins are now cleaned at leasl once every duec years. Limited studies of die bottom sedunents in wet and
extended detention ponds indicate dial toxicity limits specified by final disposal regulations are not exceeded (see TC2
Wet Ponds).
Prctteattncni may reduce maintenance costs by capturing gross settleable soUds and floatables in a smaller space dial can
be more easily cleaned. Maintenance techniques for basins include rototilUng, disking and deep ripping.
Porous pavement should be deaned at least quarteriy by vacuum sweeping and high pressure washing.
Sec Maiyland (1984) and Horida (1988) for additional guidance on die design, consttuction, and
mainlenance of infiltration systems.
REFERENCES
Adolphson Associates, 1991, "Subsurface Storai Water Disposal FacUities", Interim Report, for die Tacoma-Pierce
County Health Department
Adolphson Associates. 1989. "Storai Water Evaluation. Ctover/Chambers Basin Ground Water Management Program"
for die Tacoma-Pierce County Healdi Depaitment
Field, R. H. Masters, and M. Singer, 1982, "Stams of Poras Pavement Research", Water Resources Research, 16, 849.
Florida (Suite oO. 1988, "The Horida Development Manual", Department of EnvironmenuU Regulation.
Gofortb. GF.. JJ>. Hcaney, and W.C. Huber, 1983, "Comparison of Basin Perfonnance Modeling Techniques", Jour
EE, ASCE. 109(5), 1082. ^
Gburek, W. J, and J.B. Uri>an, 1980, "Stonn Water Detention and Ground water Recharge Using Porous Asphalt - Initial
Results", in Proceedings of fritemational Symposium on Uriian Stonn Water Runoff, Uxington, Kenmcky.
King County, 1990, "Surface Water Design Manual", King County Wasbington.
Industrial Handbook 5-8 March, 1993
Additional Information — Infiltration
Lindsey, G., L. Roberts, and W. E»agc, 1991, "Stonnwater Management InfUttation Practices in Maryland A Second
Survey", Maryland Department of the Environment
Maryland (State oO, 1984, "Standards and Specifications fOT InfUtration Practices", Depaitment of Namral Resources.
MetropoUtan Washington Coundl of Governments (MWCtXJ), March, 1992, "A Curreni Assessment of Urban Best
Managemeni Practices: Tecfamques fOT Reducing Nonpoint Source PoUution in the Coastal Zone".
MiUer, S., 1987, "Urban Runoff QuaUty and Management in Spokane" in Proceedings of die Nortiiwest Nonpoint Source
PoUution Conference, March 24-25, Seattie.
Portland Cement Pervious Pavement Manual.' Florida Concrete Products Association, Inc., 649 Vassar Stteet Orlando.
Florida, 32804 (no date).
Schueler, TJL, 1987, "Controlling Urban Runoff: A Practical Manual for Planmng and Designing Urban BMPs", Metro-
poUtan Washington Coundl of Governments. x
Shaver, E., pers. comm.. State of Delaware Departmenl of Nattiral Resources.
Stahre, P. and Urbonas, B., 1989, "Swedish Approach to InfUttation and Percolation Design", in Design of Urban Runoff
(JuaUty Conttol Americans Sodely of CivU Engineers.
Tulloch, AUce, pers. comm.. City of Modesto PubUc Works.
United States Environmental Protection Agency (USEPA), 1991, "Detention and Retention Effects on Groundwater",
Region V.
Industrial Handlxiok 5-9 March, 1993
Additional Information — Infiltration
TABLE lA. POINT SYSTEM FOR EVALUATING INFILTRATION SITES
1. Ratio between ttibutary connected unpervious area (AIMP) and die infilttation area (AINF)-
• AINF > 2 AIMP
20 points
• AIMP< AINF<2 AIMP
10 points
• 0.5 AIMP < AINF < AIMP
5 points
2. Nature of surface soU layer
Course soils widi low ratio of OTganic material
7 points t
• Normal humus soil
5 points
• Fme grained soils widi high ratio of organic material
0 points
3. Underlaying soUs:
• If die underlaying soils are courser dian surface soil assign die same number of pomts as for die
surface soU layer assigned under item 2 above.
• If tiie underlaying soils are finer grained dian die surface soUs, use Uie following points:
• Gravel sand of glacial tiU widi gravel or sand
7 points
• SUty sand or loam
5 points
• Fine sUi or clay
0 points
4. Slope (S) of die infilttation surface:
• S < 0.07 ft/ft
5 points
• 0.07 < S < 0.20 ft/ft
3 points
• S > 0.20 ft/ft
0 points
Vcgeuition coven
• HcalUiy namral vegetation cover
5 points
• Lawn is well esuiblisbcd
3 points
• Lawn is new
0 points
No vegetation, bare ground
-5 points
6. Degree of traffic on infilttation surface:
• Littie fool traffic
5 points
• Average foot traffic (parte, lawn)
3 points
• Much foot ttaffic (playing fields)
0 points
Industrial Handbook e in
* • March, 1993
Additional Information — Infiltration
Top View
Riprap'
Outtall
fe?.' Flal Basin Floor with
Oer^se Grass Turf
Back-up Underdrain
rgency Spillway
Riprap
Sealing
Basm and
Level Spreader
Side View
Back-up Underdrain Pipe in Case ol Standing Waler Problems
Source: Schueter (1987)
NOTE:
1. Backup underdrain is not used in most appltoations because plugging
occurs in soil above the drain.
2. An infiltratfon Ijasin can also be excavated (typically 2 to 6 feet deep)
as tong as the twttom of the basin is 3 feet above high seasonal water table.
FIGURE lA. INFILTRATION BASIN
Industrial Handbook 5-11 March, 1993
Additional Information — Infiltration
Top View
•. Grass Filter •
'C Grass ;:j
-Craps Debris
Screened Overflow Pipe
Inllow
MEDIAN STRIP DESIGN
Side View
20- Grass Rlter Strlo
Permeable Filter .=
Fabric One Foot
Below Surface.
Lined with Permeable Filter Fabric
Clean Washed Stone or Gravel
(1.5-10 Inch)
6-12 Inch Sand Filler
or Permeable Filter
Cloth Lines Bonom
Source: Schueler (1987)
BUILDING DRAIN DESIGN
Ot>servation Well
Sheet (Dover Maf I.
LeveT
Li^^l ^ Screen CB
Adapted from King County
Perforated Pipe
"Tfsnsr
Sump with
Solid Ud-Optionai
FIGURE IB. INFILTRATION TRENCHES
Industrial Ebndbook 5-12 March, 1993
Additional Information — infiltration
a* PVC pioa
71—r
-id Sloo* 2--
_L. 1
•8" 10 Pr-cost Mannole "iin Bottom .
Perforaled Monnot* filled as, snown —
with \ 1/2' lo y washed lJra»n flock
Monhof« has open bottom
Rl owr-amcovatsd or«a with drain rock '
-I I
ll
S
\
WITH PRETREATMENT
Side View
^ *a' !0 Precast
Concrct* Uonnotc
g'-f)- s«onnoi€ lo oa aerforatea 'n orea of Oram Aock
•'-0*
*op a' Orc»n Socx
t 1/2* to Z' •vcshed Groin riocn
y PVC collection pipe, drai
3/4' holes 9 2' etc. top of pioe
Source: Adolphson, 1991
^
TJ incn«s to
lOFaoc
Mmmum
T2 Incnvs :o Orv-»«**
s.-' -'3-'..-;
l«i<j..«..p:."
^•-•^-ilnefi Tm WOI
PVC PiO«. Ancnorvd wan
Source: Schueler, 1987
Note: See discussion on page 5-6 regarding design considerations.
WITHOUT PRETREATMENT
FIGURE IC. DRYWELL CONFIGURATIONS
Industrial Handbook 5 - 13 March, 1993
Additional Information — Infiltration
UJ
ty-) ce.
=5 O
u
•31
-a
c
—1 — t/1 —
Lu O) '/» a£ 0) y =3 OJ 3J
:3 I. Cl O -a t/1 cn yi
o> t/1 o H- <C tj Ol UJ aj -•-~^ X — LU .1.J t/1 V.
< = Ol «C CT Ol •/I cc .!_> .VI CD CT S
OL \ rj Ol 0)
u o u —
Q; •—
<u •yi
< "tr t_) ~ r O •Jl
o O CM > 3J
o ce <: =->w — UJ o; o 1/1
o = .C t— r >— UJ "O O a: c\i C3. VT) CVJ t/O I — C tr O ut • UJ = s 3
a. m CM u. •—1 CM oe > I. 1—
T T T
ier
103
i<:
>> 3J
•--
o .a
o
1)
•J 0.
TJ
o c t/1 5
CD >1
z TJ
1— l/l
VI 0 t_
X
LU 2: a.
TJ C
(0
>
CJ o cc
>.
o
(J
r ^
Industrial Handboolc 5-14 March, 1993
Additional Information — Infiltration
Poureti-ln-P1ace Slab CasteUatetj Uni c
Lattice Unit Modular Unit
Source: State of Florida
FIGURE IE. TYPES OF GRID AND MODULAR PAVEMENTS
Industrial Handbook 5-15 March, 1993
BMP: WET PONDS Considerations
So/-/s
(Z^AreaRequir^^
Jlope^
Water Availability^
Aesthetics
Hydraulic Head
^Environmental Side\
^^^-....^Effects^,^
DESCRIPTION
A wel pond has a pennanent water pool tti ttciat incoming storm water. An enhanced wet
pond includes a prctteatment sediment forebay
CALIFORNIA EXPERIENCE
There are regional flood control basins in Califoraia tbat function like wet ponds or
constructed wetlands (TC3).
SELECTION CRIIERIA
• Need to achieve high level of paruculate and some dissolved conuiminant removal.
• Ideal for large, regional ttibutary areas.
• Muldple benefits of passive recreation (e.g., bird watching, wildlife habitat).
LDVHTATIONS
• Concem for mosquitoes and maintaining oxygen in ponds.
• (Tannot be placed on steep unsttible slopes.
• Need base flow or supplemental water if water level is to be maintained.
• Infeasible in very dense urban areas.
• In Califomia the wet season is coincident with minimal plant growth.
• Could be regulated as a wetlands or under Chapter 15, Tide 23, California Code of
Regulafions regarding waste disposal to lands.
• Pending volume and depth, pond designs may require approval from State Division of
Safety of Dams.
DESIGN AND SIZING CONSIDERATIONS
Wet pool volume determined by Figures 2B and C.
• Water depdi of 3 to 9 feeL
• Wedand vegetation, occupying 25-50% of water surface area.
• Design to minimize sbori-circuidng.
• Bypass stonns greater than two year storm.
CONSTRUCTION/INSPECTION CONSIDERATIONS
• Be careful when installing wetland vegetation.
MAINTENANCE REQUIREMENTS
• Remove floattibles and sediment build-up.
• Correct erosion spots in banks.
• Control mosquitoes.
• May require permits from various regulatory agencies, e.g. Corps of Engineers.
COST CONSIDERATIONS
• Costs for providing supplemental water may be prohibitive.
Targeted Constituents
9 Sediment
O Nutrients
O Heavy Metals
O Toxic Materials
% Floatable Materials
O Oxygen Demand-
ing Substances
Q Oil & Grease
O Bacteria & Viruses
W Ukely to Have
Sigmlicant Impact
O Probable Lx>w or Unknown Impact
Implementation
Requirements
# Capital Costs
O O&M Costs
O Maintenance
O Training
High O Low
TC2
Best^
Management
Practices^
Industrial Handbook 5-16 March, 1993
Additional Information — Wet Ponds
General
The major feamres of a wet pond are shown in Figure 2A. Il is essentially a smaU lake with rooted weUand vegetation
along die perimeter. Tbe permanent pool of water provides a quiescent volume for continued settling of particulate
contanunants and uptake of dissolved contaminants by aquatic plants between stonns. The wedand vegetation is present
U) improve die removal of dissolved contaminants and to reduce the fonnation of algal mats. However, given the need to
minnnize the impaa on space, it may be cost-effective to use vertical concrele retaining walls which would not aUow for
emergent vegetation.
Thc average depdi of die wet pool is generaUy 3 to 9 feet, aldiougb greater depdis are possible with artificial mixing. The
objective is to avoid tiieraial stt-adfication that could result in odor problems. GenUe artificial mixing may be needed in
small ponds because they are effectively sheltered from die wind.
In industtial applicadons ground water or tteated process water will have to be pumped into die facility to maintain die
water level. The wel pond could be allowed to dry during the summer months. Allowing the wel pond to dry has not
been ttied elsewhere bul seems feasible since the pond need not operate during die summer mondis. The major problem
widi this concept will likely be aestiietics radier dian performance.
Wet ponds are of interest where the removal of die dissolved constinient fraction is of concern, particularly nuttients and
metals. Dissolved contaminants are removed by a combination of processes: physical adsorption to bottom sediments
and suspended fine sediments, namral chemical flocculation, and uptake by aquatic plants. A wet pond witii concrete
sides and floor would tiierefore not likely provide any advanttige over die non-vegetative ttcattneni conttol BMPs. The
relative importance of each mechanism is not weU understood. Very limited data prevents a defmitive conclusion as to
die effectiveness of wet ponds in removing dissolved contaminants. Reduction in the dissolved fraction of phosphoms
and some metals have been obseived but tbis does not necessarily mean it is removed in die pond. It may be incorpo-
rated "mto algae or absorbed onto fme paruculate matter which exits the facility in die effluent If die primary removal
mechanism is biological, wel ponds may nol be particulariy effective in removing dissolved contaminants in Califoraia
because most stonns occur during winter when plant growth is minimaL
Anodicr concept is die extended detention wel pond in which die outiet of die faciUty is restticted so as ui rettiin a
tteaonent design stonn on top of tbe wet pool for a specified time. It is believed tiiis added measure improves perfor-
mance. Tbe effea of rcstticting die oudlow is to reduce die overflow rate during die stonn increasing die capmre of
settleable soUds. However, die majority of settUng occurs between radier tiian during die stonns. Tbe extended deten-
tion zone may tiierefore provide UtUe incremental benefit. If vertical space is available die concept could be employed
because die added cost may be nominal. See TC5 Extended Detention Basins on how to deteimuie die extended deten-
tion volume.
Design
Two mediods have been proposed for die sizing of wet ponds: one predicated on die removal of particulate contaminants
only (USEPA, 1986) and one predicated on die removal of pbosphoius as well (Florida, 1988; Maryland, 1986). Tbe
fust mediod lelattis die removal efficiency of suspended soUds to pond volume. TTie second mediod provides a detention
ume of 14 days based on die wettest mondi to allow sufficient time for die uptake of dissolved phosphonis by al<»ae and
the scidmg of fine soUds where die paniculate phosphoms tends to be concenttated. The criterion of 14 days comes from
Kast et aL, 1983 who observed dial in lakes at leasl 14 days is needed for significant algal giowdi during die growing
season. In much of die United States including Maryland and Florida die growing season is coincident widi Significant
rainfall But diis is not die siUiation in Califomia where essentiaUy all of die rainfall occurs from November dirough
April. Consequentiy, die removal of phosphonis and fme solids wUl not be as high as die literature indicates.
Industrial Handbook 5-17 March, 1993
Additional Information — wet Ponds
Sizing, the Pemianent Pwl
Rgure 2B shows the relationship between perfonnance and the long-term removal efficiency for average conditions in
Califomia (USEPA (1986) as adapted in FHWA (1989)). Vt/Vj. is die ratio of die volume of die wet pond to die volume
of the mnoff of tbe mean storm event from the ttibutary watershed. The depth of die mean storm for various areas of
Califomia is shown in Figure 2C. The recommended perfonnance goal is 80%. The volume of the pond is therefore
calculated as follows:
Vb = 3Sd Aj 43560/12 = 10890SdAi (1)
where: Vb = pond volume (ft^)
S(j = mean storm depth (inches)
Aj = impervious acres in tiie tribuuiry watershed
For Aj the engineer may use directiy conneae^ impervious acres because it more correctiy represents the area being
tieated and would aUow a smaller facUity. Although impervious area and direcdy connected impervious area are not the
same, they are reasonable given tbe uncertainty of the methodology and expected pond performance.
This volume should lie compared with the 14 days detention time criterion and the more conservative volume (i.e., larger
volume) should be used for sizing.
Adding Detention Storage to the Permanent Pool
Some investigators believe that detention volume added above the pennanent pool enhances pool performance. Tbe
State of Florida, for example, requires one basin inch of detention storage be added to the pennanent pool and be bled
down over a 60 hour period. This requirement, however, adds considerably to the size of die basin, and the Uterature
does not indicate that water quality performance is improved. Therefore detention storage should be added only if the
pond is to be used for drainage conttol in addition to water quality control. As with extended detention, consideration
should be given to bypassing die facility for flows greater than die two year storm so that bed load is not trapped in die
pond.
A perforated riser oudet recommended by the Denver Urban Drainage and Flood Conuol Districts is iUusuated in
Figures 2D and 2E. Other oudet concepts arc iUustrated in TC5, Extended Detention Basins, Figure 5B.
Additional Considerations
• Place wetland vegetation around the pond perimeter and near the oudeL
Rooted vegetation around the pond perimeter serves several functions (Figure 2A). It enhances die removal of dissolved
poUutants (see T3, Constructed Wetlands); it may reduce tbe fonnation of floating algal mats; it reduces tbe risk of
people faUing into die deeper areas of die pond; and, it provides some tiabitat for insects, aquatic life, and wetiand
wildlife. Tbe "sheir for die vegetation should be about 10 feet wide witb a water depdi of 1 to 2 feet. Tbe total area of
the "sheir should be 25-50% of die water surface area. Vegetation near die exit wUl assist settUng of solids. An
altemative is a rock fdter which is used in many wastewater oxidation ponds where loss of algae in the effluent is a
common problem during tbe growth season (Rich, L., 1988).
If mesquites are of particular concem, il would be advisable to inhibit the growth of emergent wetland vegetation around
the perimeter by using steep slopes, say, 2:1, and by minimizing die amount of pond area that bas a depth less dian 18".
Gambusia (mosquito fish) can also be planted in larger ponds bul the water level must be maintained to insure dieir
survival during die dry season.
Industrial Handbook 5-18 March, 1993
Additional Information — Wet Ponds
If placement of wedand vegetation along die perimeter is not feasible consider die use of devices dial retain non-ioottxl
wedand species (Limnion, undated; Zirschky, et al, 1980). Non-rooted vegetation is more effective tiian rooted vegeta-
tion in removing dissolved nuttients and metals (see TC3 Consttucted Wedands). The vegetation grows widun die
device which is periodicaUy removed and cleaned tiiereby removing die contanunants from die facUity. The system
developed by Limnion is in use in several artificial lakes in CaUfomia to conuol nuttients.
Except for very smaU faciUties, include a forebay to faciUtate maintenance.
Use side slopes of at least 2:1 or flatter unless vertical retaining waUs are used.
• Except for very smaU fadUties, provide access to tiie forebay (slope of 4:1 or less), to die oudet, and around die
pond perimeter for cleaning.
About 10 to 25% of die surface area detennined in the above procedure should be devoted to die forebay. The forebay
can be distinguished from die remainder of die pond by one of several means: a lateral siU witii rooted wedand vegeta-
tion, two ponds in series, differential pool depdi, rock-fiUed gabions or retaining wall, or a horizontal rock fdter placed
lateraUy across the pond.
• Use energy dissipation at die inlet to avoid erosion, to promote settUng in die forebay and to minimize short-
circuiting.
• Use a lengdi to width ratio of at least 3:1 to mininuze sbon-circuiting.
Short circuiting must be minimized. Tbis can be accompUshed by using a generally rectangular configuration widi a
lengtii to widdi ratio of a least 3:1 and by placing die inlet and oudel at opposite ends. Tbe inlel and oudet can be placed
at the same end if baffling is instaUed to direct Uie water to tiie opposite end before rettiraing to die ouUeL If topography
or aestiietics requires tiie pond to have an irregular shape, die pond area and volume should be increased to compmsate
for the dead spaces.
Inlet design may affea a faciUty's hydrauUc efficiency. Tbe ttaditional approach of deadheading die inlet pipe direcdy
mto tbe pond is not satisfaaory. Experience widi wastewater ttcattneni indicates dial it is best to have multiple inlets
placed equal to tbe depdi of die pond, widi a perforated baffle kxated in front of die inlets at a distance from one to two
times die pond depdi (Kleinscfamidl, 1961). However, diis concept is not practical widi stonn water tteaonent systems.
A possible amipronuse dial should significantiy reduce short-circuiting in which die flow is split by a T or Y
(Kleinscbmidt, 1961) widi die horizontal rock filter serving as perf-orated baffle. A lateral bench widi wedand vegetation
as shown in Figure 2A should also woric. The area between die inlet and die fdter becomes die forebay. Placing large
rocks at each inlet wUl dissipate die energy and spread die water more effectively across die forebay.
Minimize water loss by infilttation tiirough tiie pond bottom.
To mainuiin die wet pool to tbe maximum extent possible excessive losses by infUttation tiirough tiie bottt>m musl be
avoided- Depending on die soUs, tiiis can be accompUshed by compaction, incorporating clay into tbe soil, or an
artificial Uner.
Freeboard of 1 fooL
Widi earthen walls, place an antiseep collar around die oudei pipe.
Thc oudel should incoiporate an andvortex device if die facUity is large (A 100 year storai must safely pass tiirough
OT around the device).
Tlie settleable solids concentiation of storai water is relatively low. obviating die need for adding dcpdi to die facUity for
sediment storage.
Industrial Handbook 5 . lo
^•i^ March, 1993
Additional Information — wet ponds
The sides of an earthen waU should be vegetated to avoid erosion. Drought tolerant groundcover species should be used
if irrigation can not occur during the summer. See TC4, BiofUteis regarding recommended plant species.
Maintenance
Check at least annuaUy and after each extreme storm event The faciUty should be cleaned of accumulated debris. The
banks of suiface ponds should be checked and areas of erosion repaired. Remove nuisance wetland species and take
appropriate measures to control mosquitoes. Solids should be removed when 10 to 15% of the storage capacity has been
lost
Limited smdies (Dewberry and Davis, 1990; Meiorin, 1991; Florida, 1991; Livingstone, peis. comm.) of die bottom
sediments indicate tbat ttixicity limits specified by final disposal regulations are not exceeded. Concenttations observed
by Dewberry and Davis (1990) were less tiian 1/1000 of toxicity Umits. If diis problem is occurring it suggests tiiat
source control BMPs need to lie improved, i
If algal Uooms are excessive consider alum treatment or tbe use of devices that retain non-rooted vegetation as dis-
cussed above.
REFERENCES
Dewberry and Davis Inc, 1990, "Investigation of Potential Sediment Toxicity from BMP Ponds", Northern Vuginia
Planning District Commission.
Florida (State of), 1988, The Florida Development Manual", Departtnent of Environmental Regulation.
Florida (State of), 1991, "Maintenance Guidelines for Accumulated Sediments in Retention/Detention Ponds Receiving
Highway Runoff*, Department of Tiansportation.
Kleinscbmidt, SJL, 1961, "HydrauUc Design of Detention Tanks", J. Boston Society of Civil Engrs., 48,4, 247.
Limnion Corporation, undated, "Nutrient Removal Using a Submersed Macropbyte System", and "MeuUs Removal
Using a Submersed Macropbyte System".
Maryland (State oO, 1986, "FeasibiUty and Design of Wet Ponds to Achieve Water QuaUty Conttol", Water Resources
Administration.
MettopoUtan Washington CouncU of CJovemments (MWCOG), March, 1992, "A Current Assessment of Urban Best
Management Practices: Techniques for Reducing Nonpoint Source Pollution in die Coastal Zone".
Rast, W., R. Anne Jones, G. Fred Lee, 1983, "Predictive CapabUity of U.S. OECD Phosphonis Loading-Euttophication
Response Models", J. Water PoUution Conttol Federation, 55,7,990.
Rkh, L, 1988, "A Critical Look at Rock FUters", J. of Envir. Engr, Amer. Society of Civil Engrs, 114,219.
Shepp, D., D. Cole, and F. GalU, 1992, "A Field Survey of die Performance of Oil/Grit Separators", MettopoUtan
CouncU of Governments.
United States Environmental Protection Agency, 1986, "Methodology for Analysis of Detention Basins for Conttol of
Urban Runoff Quality".
Industrial Handbook 5-20 March, 1993
Additional Information — wet ponds
Urban Drainage and Flood Conooi Disttict, Denver Colorado, "Urtian Stonn Drainage Criteria Manual - Volume 3 - Best
Managemeni Practices - Stonnwater CJualily", S^iember 1992.
WaDcer, W, 1987, "Phosphorus Removal by Urtian Runoff Detention Basins", in Lake and Reservoir
Management, North American Society for Lake Management, 314.
Zirschky, J., and S. Reed, 1988, "Tbe Use of Duckweed for Wastewater Treattnent", J. Water Pollution Conuol Federa-
tion, 60, 1253.
ll
Industrial Handbook 5-21 March, 1993
sr
CL
69 S
a
r
Sklu Slope No Slaaper hon 4:1
2
n
ut
tll lot al 2ona 25 lo S0%
ol Tolal Suilaca
FoiatMy
Embaiikdiuiil SIdu Slope
No Sluaptti llianSM
EiiibanKinanI
Accafilu OuUal
1011 (min.) Paimaneiil W.S. PLAN
4:1 or
Flatlar
Average Doplh: NOT TO SCALE
4.0 lo 8.0 II
1211 (max.)
Lhloral
Zona 3:1 Of
Flallef SECTION A'-A
Ovailtow lor
Larger Sloimi
Energy
Olssipalor
Detention Volume
7=
'olume 13 lo 5II
Pormaneiil Pool
Solid Oilving
Suilaca Lhloral Zona/Oarin
EnrivigarKy Spillway Flood Laval
(31 Spillway Ciutl
(a g. 100 yr)
Enibankiiiunl
Sfillhwuy Ciatl
Culoll fla'«"<
Collais /Culvoil
OullkJW -->
Oullul Woiks
(sou dui ull)
SECTION
NOT TO SCALE
Provide
Bollom Drain
(Used By Permission. UDFCD. 1992)
FIGURE 2A. PLAN AND SECTION OF A WE P POND
>
Q.
Q.
TV
o'
=3
SL
5"
o
o"
=3
a
2P
Additional Information — wet ponds
-.00
so
-.00
so
^ : '• 1
• ! 1
! i . !
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
i
i
i ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
• / i !
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
i
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
•
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
/
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o
ao
70
BJ
o
iZ
tt. 50
BJ
<
1 "
Bl
C
ta
? 30
20
10
o 0.1 0.2 O.A 0.6 0.8 1 2 4 S 8 10
WET BASIN VOLUME / RUNOFF VOLUME, V, / v
Source: FHWA (1989)
FIGURE 2B. TSS REMOVAL VERSUS V/VR RATIO
TC2
Industrial Handbook 5-23 March, 1993
Additional Information wetponds
0.60 0.50 0.40
/
K. K. 0.40
Source: Woodward-Clyde, 1989 • ^ 0.60'
0.50
FIGURE 2C. AVERAGE STORM EVENT
DEPTH (INCHES)
Industrial Handbook 5-24 March, 1993
Additional Information — wet Ponds
Thraadad Cas ^smovaola & Loduola
Ovarftow Gnta ior,
Largar Siorms Stiff StMi
3cr»on for
Trasn Skirnmor
Op«n on Too
i 3oaom
Parmanam Pool Hsa 40 of Ris^r
Waiar Quaiirv
Riser pipa (3a« OetatI)
Notas: 1. Altamata designs are accaoabi* as long as rtm
fiydraulics provides t>e required am tying times.
2. Usa rash siummer screens ol stilt green steal
material as protect parloratad hser. Must extend
from ne top of tm riser to 2 It. below r)e
permanempool level. OUTLET WORKS
NOTTO SCALH
Size 3ase to Prevent
Hydrosatie Upiill
Notes: 1. Minimum number al holes - S
2. Minimum hole diamatar • Oia.
1 -1 /2* diamater Air
V«m in Thr«ad«d
Watar Quality
Outlat Holm
Ouctila Iron or
Steal Pipa
WATSH QUALfTY
RISER PIPE
NOTTOSCALE
(Used By Permission, UDFCD, 1992)
Maximum Number of Pertarated Columns
Riser
•iamelar Hole Oiametar, inehes
f«-) 1/4-1/r 3/4* r
4 8 8 --
S 12 12 9 -
s 16 16 '2 s
TQ 20 20 14 10
12 12
Hole OiameMf
In.)
Area
r«.2)
1/8
1/4
3/8
1/2
s/a
3/4
7/8
1
0.013
0.049
0.110
0.196
0J07
0.442
0.S01
0.78S
FIGURE 2D. WATER QUALITY OUTLET
FOR A WET POND
Industrial Handbook 5-25 March, 1993
Additional Information — wet ponds
«
E
o >
c
c
"S O
0.01
0.2 0.4 0.6 0.8 1.0 2.0 4.0 6.0 8.0 10
Raquirsd Araa par Row firu^)
Sourca: Douglas County Slorm Drainage arxi Technical Cnteria. 1986. (Used By Permission, UDFCD, 1992)
FIGURE 2E. WATER QUALITY OUTLET SIZING:
WET POND WITH A 12-HOUR DRAIN
TIME OF THE CAPTURE VOLUME
Industrial Handbook 5-26 March, 1993
BMP: CONSTRUCTEDWETUNDS
FLOW
TREES
AQUATIC PLANTS
Considerations
Soils
^rea Required
Slope
"^ater A vai lability "
Aesthetics
Hydraulic Head
(Environmental Sides
DESCRIPTION »
Constructed wetlands have a significant percentage of the facility covered by wetland
vegetation.
EXPERIENCE IN CALIFORNU
Research faciiily constructed in Fremont in 1983 by the Association of Bay Area Govem-
ments. Several communities (Davis, Orange County) have regional detention ponds that
are essentially consttucted wedands.
SELECTION CRITERIA
• Need to achieve high level of particulate and some dissolved contaminant removal.
• Ideal for large, regional ttibutary areas.
• Multiple benefits of passive recreation and wildlife.
LBVnTATIONS
• Concern for mosquitoes.
• Cannoi be placed on steep unstable slopes.
• Need base flow to maintain water level.
• Not feasible in densely developed areas.
• Wet season coincident with minimal plant growth.
• Nutrient release may occur during winter.
Overgrowth can lead to reduced hydraulic o^iacity.
• Regulatory agencies may limit water quality lo constructed wedands.
• May be regulated under Chapter 15, Tide 23, California Code of Regulations regard-
ing waste disposal to lands.
DESIGN AND SIZING CONSIDERATIONS
• Suitable soils for wedand vegetation.
• Surface area equal to at leasl 1% and preferably 2% of the tributary watershed.
• Forebay.
CONSTRUCnON/INSPECnON CONSIDERATIONS
• Involve quaUfied wetland ecdogist to design and install wedand vegetation.
• Establishing wetland vegetation may be difficulL
MAINTENANCE REQUIREMENTS
• Remove foreign delMis and sediment build-up.
• Areas of bank erosion should be repaired.
• Remove nuisance species.
• Control mosquitoes.
Targeted Constituents
9 Sediment
% Nutrients
9 Heavy Metals
9 TOXIC Materials
9 Fhatable Materials
^ Oxygen Demand-
ing Sutxstances
# 0/7 & Grease
O Bacteria & Viruses
9 Ukely to Have
Sigmlicant Impact
O Probable Low or
Unknown Impact
Implementation
Requirements
# Capital Costs
O O&M Costs
O Maintenance
O Training
High O Low
TC3
Best'
Management
P^actlces^
Industrial Handbook 5-27 March, 1993
BMP: CONSTRUCTED WETLANDS (Continue)
COST CONSIDERATIONS
* Wetlands being shallower tban wel poods may result in larger area requirements.
• Costs for providing supplemental water may be prohibitive.
Industrial Handbook 5-28 March, 1993
Additional Information — constructed wetiands
General Information
Although namral wetlands are being used to treat storm water, regulatory agencies do not favor tbis use, except as a final
"polishing" step after treatment by one CM- more of the tteatment conttol BMPs presented in this chapter. Constrnaed
wetlands, in contrast, are built specifically for treating storm water nmoff. They arc not wetiands created as mitigation
for tbe loss of natural wetlands. Consequentiy, there is no intention to replicate the complete array of ecological fimc-
tions of a wetland (e.g., the presence of wildlife), although it can be done. A constructed wetland is generally one of the
more aesthetic diian the tteatment systems. It is likely tbat constructed wedands will be used only in very large industrial
sites, but small facilities widi concrete retaining walls to conserve space will also likely be effective.
The simplest form of a constructed wetland includes a rectangular basin with a forebay and wedand vegetation area. Tbe
deeper forebay (3 to 6 feet) traps floatables and die larger settieable solids, facilitating maintenance as well as protecting
the wetland vegetation. Alternatively, a detention pond may be placed before thc wetland, to remove settieable solids
and to protect the wetland from extreme increases in water elevation. The wetland vegetation is placed in a shallow pool
that extends laterally across the basin. Construction of low flow channels through emergent vegetation can cause storm
water to short circuit through channels radier dian through the wetland vegetation.
Placing rooted wetland species through the majority of tbe faciiily adds to die cost, in comparison to a wet pond. How-
ever, il is believed by many practitioners diat the vegetation improves performance. Placing the vegetation across the
facility as illustrated in Figure 3A improves settiing of particulates and uptake of dissolved contaminants. As die
constructed wetland is shaUower than a wet pond, there may be better contact between the water and soil which may be
die primary remover of dissolved phosphorus and metals.
Tbe vegetation reduces the effeci of wind which can cause significant short-circuiting in a wet pond. Water loss in a
wedand may not be greater and possibly less than a wet pond. Evapotranspiration from die plants will be greater in a
wedand bul evaporation from the water surface may be less because the dense vegetation eliminates the effect of the
wind. Tbe net result may be a slower rate of water loss. Conceivably a constructed wedand could be made smaller dian
a wet pond, given tbe benefits of tbe vegetatioa Bul experience is too linuted to identify how die size might be altered
from what is calculated for a wet pond.
Relying on volunteer plants to cover die vegetated area will delay complete coverage for several years and may allow the
invasion of undesirable species or dominance by one or two species such as cattails which tend to flourish in disturbed
conditions. Complexity is promoted by varying water depth dirough the vegetated area radier dian keeping die depdi
uniform. Preferred species to maximize tbe removal of (^solved metals are Salicomia pacifica (cadmium, copper and
lead), Justicia americana (cc^iper), Potamogeton crispus (cadnuum), Phragmites communis (zinc), Carex stricta (zinc),
and Scirpus lacusttis (zinc) (Silverman, 1982).
There is some question as to tbe incremental benefit of wetland vegetation in California, inasmudi as most of tbe wet
season occurs when the vegetation is donnanL Tbe minimum desirable temperaoire for cattails, sedges, and bulnishes is
lO^C, 140C, and 16PC, respectively (USEPA, 1988). For most of California, mean temperatures during die winter
mondis are 5 to lO^C; along the south coast they range from lO^C to IS^C. Tbe primary removal mechanisms for
dissolved phosphorus and metals are adsorption by die soil and use by non-rooted vegettition. Rooted vegetation obtains
nuttients from die soils, not from the water, unless the vegetation is placed in graveL In contrast non-rooted vegetation
removes nutrients and metals from die water (Guntenspergen, et al., 1991). It can be expected dial soil adsorption will
continue during the winter to some extenL Removal of metals and nutrients by non-rooted vegetation may not occur, or
will at leasl be significantiy reduced because of die lack of growth. In contrast, loss will occur from vegetation die-off or
dormancy. Tbe net effect over a 12 month period may be that a constmcted wetland is no more effective than a wet
pond, particularly widi regard to tbe removal of dissolved phosphorus and metals.
Industrial Handbook 5-29 March, 1993
Additional Information — Constructed Wetlands
The above concem is partially confirmed by research at die experimental wetland/wet pond in Fremont (Meiorin, 1991).
Tbe author states that the "uptake of nutrients ... was low because most storms occurred in winter when plant growtii was
reduced by ambient temperatures, short day lengths and low lighl levels". Despite die use of die word "low", phospho-
rus removal during tbe winter months was aboul 50% which is not noticeably belter than removal in a wet pond. The
removal of nitrogen was negative. Resuspension of plant material and detritus also occurred during the winter.
Despite die concerns, the wedand bottom soils are possibly a more significant mechanism for removing phosphoms and
metals. However, die experience wilh consttucted wetlands treating wastewater seems to indicate phosphorus removal
occurs in the first two to three years bul then removal rates decrease dramatically and have beccme negative in some
cases (Faulkner and Richardson, 1991). Tbis result appears ID be due to samration of die soil and die plants reaching
maximimi densiiy. However, metals removal may continue. Nitrogen removal does not degrade over time because it is
a bacteriological process. This process is vety temperamre dependent and therefore would be expected to be lower in
die winter. *
Using gravel as die substrate may be a suitable approach in small facilities. Because the gravel is lacking in nuttients
certain emergent species will uike tiieir nuttients from die water (Thut, 1988). See Reddy and Smith (1988). Harvesting
may also be more practical with this approach.
Of particular concern in many areas of Califomia will be mosquitoes. Thick stands of emergent vegetation provide an
ideal breeding habitaL If Gambusia (mosquitt) fish) are inttoduced inlo die facility die design musl include a deep pool
area where the fish can reside during die dry season. Tbe forebay can serve diis function.
.Desiyn
In die most comprehensive review to date of wetiands tteating storm water. Sleeker et al. (1992) found considerable
variation in die perfonnance of 26 facilities, bodi natural and constracted. All were located on large watersheds widi
mixed land uses, not industrial sites. There appeared b) be no relationship belween perfonnance and die size (sur£ice
area) of die wedand. The surface area of die ten constrnaed wedands varied from 03% to 12.6% of die ttibutary area.
Tbe removals of suspended solids and phosphorus ranged from 50 to 95% and 37 tt) 92%, respectively, for nine of die
10 facilities. Thc smaUest facility removed 85% of die suspended solids and 37% of die phosphorus. Tbe audiors were
unable to relate die variability of performance to any factw of design or operation. Consttucted wedands perfcsmed
somewhat better dian nattiral wedands. The only conclusion that might be safely drawn from diis study is diat a surface
area greater dian aboul 1 or 2% of the ttibutary watershed is not justified, given die uncertainty of any improvement in
perfonnance widi die increase in size. Lacking, however, are data on die percent^e of each watershed dial is impervi-
ous.
The fadlity can be sized using die same procedure oudined for Wet Ponds, TC2. However, inasmuch as a wedand is
sbaDowcr dian a wet pond, sizing die wetland for die same Vy/Vr as a wet pond requires considerably more surface area.
Given die likely advantttges of a consttucted wedand over a wet pond, some may consider diis tt) be an unreasonable
penalty. It is thcrefwe recommended diat surface area of die constructed wedand not exceed diat which would be
detennined for a wet pond.
Additional design considerations include:
• Have 25% to 50% (forebay and afterbay) 3 to 6 feet deep, and remaining area 6 in. to 24 in. deep or as appropriate
for die wedand species selected. Tbis geometiy should provide satisfactt)ry conditions for wedand wildlife (Adams
etal., 1983).
• Sitk slopes of at least 4:1 to a water depdi of 2 feet except on very small facilities where retaining walls may be
used to conserve ^cc. If retaining walls arc used, die area must be fenced for safety.
Access for maintenance vebkles to tbe forebay, tbe oudet, and around die perimeter.
Industrial Handbook 5-30 i.
^ ^ March, 1993
Additional Information — Constructed Wetlands
• Freeboard of at least 1 foot
• With earthen contained facilities, install an antiseep collar on the oudet pipe.
• Tbe soils must be suitable for wedand vegetation. If necessary organic soils (18 to 24 in.) must be imported to the
site.
• The soil must have an affinity for phosphoms. Soils with aluminum and iron are best. Soils saturated with phos-
phorus or a metal specie may cause the concentrations of tiiese contaminants to increase in die overiying water.
• Minimize short-circuiting by placing energy dissipators at the iidet, and by having a high lengdi to width ratio.
Short circuiting musl be minimized by using a generally rectangular configuration with a length u> width ratio of a least
3:1 and by placing tbe inlet and oudet at opposite ends. Tbe inlet and oudet can be placed al the same end if baffling
(islands) is installed to direct die water to tbe opposite end before rettiming to the oudet If topography or aestiietics
requires the wetland to bave an irregular shape, the pond area and volume should be increased to compensate for the
dead spaces. Energy dissipators and entranc^ baffles will spread die water laterally across die facility.
• Minimize water loss by infiltration tiirough die wetland bottom.
• Supplemental waler may be needed to avoid loss of rooted vegetation during the dry period.
To maintain tbe wel pool to the maximum extent possible excessive losses by infdtration tiirough tiie bottom musl be
avoided. Depending on die soils, this can be accomplished by compaction, incorporating clay "mto tbe soil, or an
artificial liner. Wetland vegetation species bave evolved to handle die stress of seasonal variations in water availability.
However, during the dry season there must be sufficient water to avoid complete desiccation of plant roots. Conse-
quentiy, constmcted wetiands are infeasible in areas where diere is a lack of either a baseflow or near-surface ground
water duiing tbe dry season. Supplemental water such as pumped ground water and treated pnxess wastewater may
have to be used.
• A wetland ecologist should prepare die planting design and specifications, and oversee the planting.
Constmcted wetlands may nol need antivortex and trash rack devices on their oudets like a wel pond because of tbe
rooted vegetation. See TC2, Wet Ponds regarding iidel design. Design concepts for oudet devices are discussed in TC5
Extended Detention Ponds. See Josselyn (1982) regarding wedand plant considerations. Establishing wedand vegeta-
tion initially may be difficult and require multiple plantings.
Maintenance
• Check at leasl annuaUy and after each extreme storm event.
• Remove accumulated foreign debris.
• Repair areas of slope erosion.
• Emptoy mosquito countermeasures as required by local authorities.
• Clean deposits from the forebay when a loss of capacity is significant, probably every 3 to 5 years depending on die
land use (see TC2, Wet Ponds), OT wben the concenttations of toxicants in die sediments are reaching a level of
concem.
There is some question as to whether annual harvesting of rooted vegetation is eidier practical or effective at reducing
seasonal losses of nuttients and prolonging the life of die faciUty (USEPA, 1988). Tbe benefits of harvesting may depend
upon die wetiand specie (Suzuki, T. el aL, 1991). Placing rooted vegetation in gravel beds rather dian soil may make
harvesting practical If harvesting is u> be done, it should occur twice per season, in die early summer wben nutrient
content in die plant material is at its peak, and in die fall before plant dormancy. Given tbe significant role of die bottcm
soil in removing metals and phosphonis its replacement may be required, although, probably not more frequentiy than
once every few decades. Cleaning tbe forebay more frequendy is important as noted above.
Industrial Handbook 5-31 March, 1993
Additional Information — constructed wetiands
Anodier consideration is the regulatory impUcations of removing accumulated material from consttucted wedands. Do
sucb actions require a 404 or otiicr pennil? Al present, constmcted wetlands arc excluded from diis requirement
(Ritt±ic 1992).
REFERENCES
Adams, L., Dove L£., Di. Leedy, and T. FrankUn., 1983, "Urban Wedands for Stoimwater Control and Wildlife
Enhancement - Analysis and Evaluation", Urtian Wildlife Research Center, Columbia, Maryland.
Faulkner, S. and C. Richardson, 1991, "Physical and Chemical Characteristics of Freshwater Wedand SoUs", in Con-
sttucted Wetlands fnr Wastewater Treattnent ed. D. Hammer, Lewis PubUshers, 831 pp.
Guntenspergen, GJL, F. Steams, and J-A. Kadlec, 1991, "Wedand Vegetation", in Consttucted Wetiands for Wastewater
Treattnent, ed. D.A. Hammer, Lewis PubUsberi 831 pp.
Josselyn, M., 1982, "Wedand Restoration and Enhancement in CaUfOTuia", Instittite of Marine Resources, University of
California.
Kuber, L, 1990, "Waler PoUution Conttol Aspects of Aquatic Plants", Municipality of MettopoUtan Seattie.
Livingstone, E., pers. comm., Florida Departmenl of Environmental Conservation.
Meiorin, E.C., 1991, Urban Runoff Treattnent in a Fresh/Brackish Water Maish in Fremont, CaUfomia", in Consttructed
Wetiands for "Wastewater Treatment, Ed. D. A. Hammer; Lewis PubUshers.
MettopoUtan Washinguin Council of Governments (MWCOG), March, 1992, "A Current Assessment of Urt)an Best
Management Practices: Techniques for Reducing Nonpomt Source Pc^ution in the Coastal Zone".
Reddy, K, and W. Smith, 1987, Aquatic Plants for "Water Treatment and Resource Recovery, MagnoUa Press.
Rittiiie, S, 1992, letter to R-B. James, Chairman of die Management Committee of die Santa Clara Valley Nonpoint
Source PoUution Control Program.
SUverman, G, 1982, "Wedands for OU and Grease ConttoP, Tech Memo. 87, Association of Bay Area Govemments.
Suziki, T., W.GJ\. Nissanka, and Y. Kuribara, 1991, "AmpUfication of Total Dry Matter, Nifrogen and Phosphorus
Removal from Stands of Phragmites austraUs by Harvesting", in Constmcted Wetlands for Wastewater Treatment, Ed.
D. A. Hammer, Lewis Publishers.
Sttecker, E.W., JM. Kersnar, and EJ). DriscoU, 1992, "Tbe Use of Wedands for ConttoUing Stormwater PoUution", for
USEPA Region V.
Tbul, R., 1988, "Utilization of Artificial Marshes for Treattnent of Pulp MUI Effluents", in Constructed Wetlands for
Wastewater Treattnent, Ed. D. Haouner, Lewis PubUshcis.
United States Environmental Protection Agency (USEPA), 1988. "Consttucted Wedands and Aquatic
Plant Systems for Municipal Wastewater Treaonent, EPA 625/1-88-022.
Industrial Ebndbook 5-32 March, 1993
BMP: BIOFILTERS
CHECK DAM
(optional)
Considerations
(^^^naRequi^l^
C^ter AvailabH^^
Aestheths
Hydraulh Head
Environmental Side
Effects
DESCRIPTION »
Biofiiters are of two types: swale and strip. A swale is a vegetated channel dial treats
concentrated flow. A sttip treats sheet flow and is placed paraUel to die contributing
surface.
EXPERIENCE IN CALIFORNU
No biofiiters specificaUy designed to tteat storm water have been located. However,
instances of "biofilter by happenstance" exist in northern communities (Davis, Sacramento,
Turlock, Fresno) where storm water is discharged to a grassed area prior to an inlet or an
infilttation area.
SELECTION CRITERU
• Comparable performance to wet ponds and constmcted wetlands.
• Limited to treating a few acres.
• AvailabUity of water during dry season.
LIMTTATIONS
Poor performance bas occurred but dils appears to be due to poOT design.
May be limited to areas where summer irrigation is feasible.
Can be difficult to maintain sheet flow in strips.
Can be difficult to avoid channelization in swales.
Cannot be placed on steep slope.
Area required may make infeasible on industrial sites.
Proper maintenance required to maintain health and density of vegetation.
DESIGN AND SIZING CONSIDERATIONS
The surface area is defined by Figure 4A.
The minimum width fOT a swale is detennined by Mannings Equation.
Minimum length of a strip is 10 feet
The longittidinal slope must not exceed 5%.
Use a flow spreader and energy dissipatOT at the entrance of a swale.
Good soils are important to achieve good vegetation cover.
CONSTRUCnONANSPECnON CONSIDERATIONS
• Make sure soils are suitable fOT healthy vegetation.
• Level cross-section and even longittidinal slope fOT swales.
• Achieve sheet flow widi ships.
Targeted Constituents
% Sediment
9 Nutrients
Q Heavy Metals
O Toxh Materials
O Fhatable Materials
O Oxygen Demand-
ing Substances
O 0/7 & Grease
O Bacteria & Viruses
• Ukely to Have
Significant Impact
O Probable Low or Unknown Impact
Implementation
Requirements
O Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
TG4
Best'
Management
Practices'*
Industrial Handbook 5-33 March, 1993
Additional Information — Biofiiters
A biofdter swale is a vegetated channel dial tooks similar tti, bul is wider lhan, a ditch dial is sized only to ttansport
flow. The biofUtcr swale must be wider to maintain low flow velocities and to keep die depth of die water below die
height of die vegetation up to a particular design event A fdter strip is placed along die edge of die pavement (its fidl
lengdi if possible). The pavement grade musl be such as to achieve sheet flow to tbe TnaTimiim extent practical along
die Sttip.
Vegetated biofiiters wiU likely see Umited appUcation in industtial settings. Strips are most suitable for paridng tots
which under tbis general pennit do not require consideration unless they drain to a drainage system dial also receives
flows frran die mdustrial activities of concem. Widiin die mdustrial site itself conditions are usuaUy not suitable fOT
locating a grassy area next «> a paved area. TypicaUy, die industrial area is paved to tbe property Une. If die sttirm
water passes dirough a ditch priw to leaving die site il may be possible tti widen die ditt:h inui a swale.
»
Tbe peifOTmance of biofiiters is probably somewhat less tban wet ponds and constracted wetiands because die latter
provide treatinent bodi during and between storms. Some researchers bave observed poOT performance, recommending
dieir use only in combmation widi odier ttcattneni conttol BMPs. However, most field research on swale perfonnance
has been conducted on grassed roadside ditt±es. A swale musl be wkler dian a ttaditional roadskJe ditch, to avoid
excessive flow velocities which topples tbe grass and causes cfaanneUzation.
The swale bottom must be as level as possible; energy dissipation and a ftow ^reader should be placed at die enttance
to mimmize cfaanneUzation. The pavement must be as level as possible along its boundary widi a biofilter sttip. Thc
pavement edge should be left dear, dial is, no curbs. Paridng staU btocks must be open to pass die flow as unhindered
as possible. Use of curb cuts in curbs is not a satisfactory approach. The cuts channeUze die water and can clog witii
debris. Tbe performance of snips may be compromised by die faUure to achieve sheet flow at die interface between
tbe paved area and tbe strip.
Turf grass is die preferred vegetation. Figure 4B shows recommendations for seven spedes of ttirf grass and one
ground cover plant for various areas of CaUfomia (Youngner, et al, 1962). More recent infonnation in diis regard is
also shown in Figure 4C (CCAE, 1984). Turf grass wUl require summer irrigation to remain active. Altiiough il has
not been ttied it may be possible to allow die grass to become dormant during die summer smce die btofdter is only in
service during die wel season. Tbe biofilter could be irrigated beginning in October to bring "it to a healdiy condition
priOT U) die first storms. Ground cover spedes suitable for a non-irrigation sittiatioo may work but it also has not been
tried. Thc soU must be of a fertiUty and porosity dial altows fOT healtiiy vegetation. A porous soil also promotes
infUttation. See die references dial foUow for Agriculttiral Extensive pubUcations on efficient water use by ttirf
grasses.
If erosion of die swale is of concem because of die difficulty of maintaining a good grass cover, consider die use of
concrete grids (see Infilttation Systems) OT sinular malerial. Anodier concept is b) use check dams to divide the swak
into a series of terraces, reducing die longittidinal stope to perhaps 1%, diereby reducing flow velodties.
Desiyn
Several mediods have been proposed to size biofdters (Homer, 1988; FHWA, 1989; EEP, 1991; Tolhier. el al., 1976).
However, information on die relationship between biofdter area and perfonnance is lacking for urban conditions.
Figure 4A uses die niediod of Homer (1988) widi die 2-ycar storm as die design event, a slope of 3%, and a grass
hdght of 4 inches. A biofdter is sized to tteat afl stonns up to a particular design event TTic design event can be
relatively smaU because die aggregate of aU smaU events represents die majority of pollutant mnoff. Reseani in
western Washington (Metro, 1992) found dial a biofdter sized according to tiiis technique removed 80 percent of die
su^iended soUds and attached poUulants and 50% of die soluble zinc. It was not abte to remove dissolved phosphoms
OT copper.
Industrial Ebndbook s x±
^ "^ March, 1993
Additional Information — Biofiiters
Hgure 4A is meant for guidance only and should be used with caution in areas where predpitation varies gready
because of tenain.
The design engineer musl determine tbe widtii of a swale using Manning's Equation and die 2-year rainfall intensity
(Califomia, 1976) appropriate to the site. An "n" of 0.20 is recommended (Metro, 1992). The design engineer musl also
calculate the peak flow of die lOO-year event to determine die depdi of a swale. Since a width using an "n" of 020 is
generally wider than what is required of a grass lined channel, chaimel stabiUty should not be of concern. It is generaUy
nol necessary to have a bypass fOT tbe extreme events because the minimum width specification combined with the
relatively gentle slope avoids excessive velocities. If erosion al extreme events is of coticera, consider the above
concepts to minimize erosion.
Tbe design engineer can make the swale wider tban detennined in die above step, witb a corresponding shortening of the
swak length to obtain die same surface area. (However, diere is a practical Umitation on how wide the swale can be and
StiU be able to spread die flow across tbe swale width. Splitting die flow into multiple inlets and/or placing a flow
spreader near die storm inlet should be incorporated into die design. A concept that may work is to place a level 2"x
12" timber across tbe widdi of die swale pcibaps 10 feel from die pipe outiet Place gravel between die outiet and the
timber, to witiiin 2 inches OT so of tiie top of the timber. Place large rock immediately near die outiet to dissipate the
flow energy; the rock also may help distribute the flow. The timber wiU function like a weir. Flow spreaders have seen
limited appUcation and dieir effect on perfonnance has not been evaluated.
Tbe problem of spreading the flow across the width of the swale may limit its use to tributary catchments of only a few
acres. The nunimum width based on using Manning's Equation results in widths of 3 to 12 feet per acre of Loipervious
tributary surface, depending on the location and longitudmal slope.
A minimum length of 10 feel is recommended for biofilter strips. Length here is defined as die measurement in the
direction of flow from die adjoining pavement Lengths of 20 to 50 feel have been recoinmended by most practitioners
perhaps because of the concem lhal sheet ftow cannot be maintained. Wherever room pennits a length greater dian 10
feet should be used. The short length is recommended in this handbook because space is at a premium al most existing
induslrial sites: 10 feet should work satisfactory if good sheet flow is maintained and no obstructions such as curbs are
placed along the pavement edge.
The type of strip discussed here is nol to be confused with the natural vegetated buffer strip used in residential develop-
ments to separate tbe bousing from a stream or wetland. As tbe later type follows die natural contour flow
channelization is more likely and lengths of 75 to 150 feet are recommended.
The lengdi of pavement priw to die strip should not exceed a few hundred feet to avoid channelization of large aggre-
gates of mnoff along die pavement before it reaches tbe pavement edge. To avoid channelization, care musl be taken
during constmction to make sure that the cross-section of the Uofdler is kvel and dial its longitudinal slope is even.
Channelization wiU reduce the effective area of the biofilter used fOT treatment and may erode die grass because of
excessive velodties.
Maintenance
Tbe fadUty should be checked annuaUy for signs of erosion, vegetation loss, and channeUzation of die flow. The grass
should be mowed when it reaches a hdght of 6 inches. AUowing die grass to grow taUer may cause il to tiiin and
become less effective. The cUppings should be removed.
Industrial Handbook 5-35 March, 1993
Additional Information — Biofiiters
REFERENCES
California (State oO, 1976, "RainfaU Analysis for Drainage Design, Volume 3, Intensity-Duration-Frequency Curves",
BuUetin No. 195, Department of Water Resources.
CaUfomia Cooperative Agriculttiral Extension (CCAE), 1984, "Selecting tiie Best Turf Grass", Leaflet 2589.
CCAE, 1985, "Turfgrass Water Conservation", BuUetin 21405.
CCAE, 1991, "Effluent Water for Turfgrass Irrigation", BuUetin 21500.
Federal Highway Administration (FHWA), 1989, "Retention, Detention, and Overland Flow for Pollutant Removal of
Highway Stonnwater Runoff (Draft)", Report No. FHWAyRD-89/203.
Homer, RJL, 1988, "BiofUttation Systems for Storm Runoff Water Quality Conttol", Washington State Department of
Ecology.
lEP, 1991, "Vegetated Buffer Sttip Designation Metiiod Guidance ManuaT', Narragansett Bay Project
Lager, J.A., W.G. Smitii, and G. Tchobanoglous, 1977, "Catchbasm Technology Overview and
Assessment", USEPA 600/2-77-051.
MettopoUtan Washington Coundl of Govenunents (MWCOG), March, 1992, "A Current Assessment of Urban Best
Management Practices: Techniques for Reducing Nonpoint Source PoUution in die Coastal Zone".
MunkipaUty of MettopoUtan Seattie, (Metro), 1992, "Pollutant Removal Effectiveness of a Designed Grassy Swale in
Moundake Terrace, Washington (Draft)".
Sacramento County Cooperative Agriculttiral Extension, "Water Effident Landsc^ Plants" by Pamela S. Bone,
Environmental Horticultural Notes.
Tolhier, E.W, and BJ. Barfield, 1976, "Suspended Sediment FUttation Capadty of Simulated
Vegetation", Trans. American Sodely of Agriculttiral Engineers, 19, 678.
Youngner, V.B., J.H. Madison, M.H. KimbaU, and W3. Davis, 1962, "CUmatic Zones for Turfgrass in Califomia",
Califomia Agriculmre, 16 (7), 2.
Industrial Handbook 5-36 March, 1993
Additional Information — siofitters
FIGURE 4A. SIZING GUIDELINE FOR BIOFILTERS
(SQ. FTJIMPERVIOUS ACRE)
Industrial Handliook 5-37 March, 1993
Additional Information — Biofiiters
W«ll acapcnj to irea
Adaptable with higner maintenanc
Better adapted grass available
.Not adaptable
BERMIUOA GRASS
FIGURE 4B. STATE OF CALIFORNLA. SHOWING
MOST SUITABLE TURF GRASS SPECIES
Industrial Handbook 5 . 38 March, 1993
Additional Information — Biofiiters
COLD TOLERANCE
(winter color persistance)
High Crsecing oenigrass
Kaniucky oiuegrass
^ea fescue
Colcnial oentgrass
Hignlano dar.tgrass
Perennial r/egrass
Tall fescue
Weeping aikaligrass
Dichcndra
Zoysiagrass
Commen bermutJagrass
Hybrid tjermudagrass
Kikuyugrass >
Seashore paspalum
Low St. Augustinegrass
HEAT TOLERANCE
Hign
I
Uow
lovsiagrass
-••~r-C ^e^-nucagraso
5easncre ^asDai'jrr
3;, AuQust-.-iscrass
•^:kiJvug^^ss
•2.-=eoi.-ig ;enrgras3
•".eniucHv aiuegrass
-iignianc bentgrass
=erenniai ."/egrass
Colonial oentgrass
Weeping aikaligrass
Bed fescue
MOWING HEIGHT ADAPTATION
High cut Tall fescue
Bed fescue
Kentucky pluegrass
Perennial ryegrass
Weeping aikaligrass
St. Augustinegrass
Common bermudagrass
Dichondra
Kikuyugrass
Colonial bentgrass
Highland bentgrass
Zoysiagrass
Seashore paspalum
Hybrid bermudagrass
Low Cul Creeping bentgrass
DROUGHT TOLERANCE
High HyOrid bermudagrass
Zoysiagrass
Common bermudagrass
Seashore paspalum
St. Augustinegrass
Kikuyugrass
Tall fescue
Red fescue
Kentucky bluegrass
Perennial ryegrass
Highland bentgrass
Creeping bentgrass
Colonial bentgrass
Weeping aikaligrass
Low Dicftondra
MAINTENANCE COST
AND EFFORT
High Creeping bentgrass
Dicfiondra
Hybrid bermudagrass
Kentucky bluegrass
Colonial bentgrass
Seashore paspalum
Perennial ryegrass
St. Augustinegrass
Highland bentgrass
Zoysiagrass
Tall fescue
Common bermudagrass
Low Kikuyugrass
FIGURE 4C. ADDITIONAL INFORMATION ON THE
SUrrABILITY OF TURF GRASS SPECIES
Industrial Handbook 5-39 March, 1993
BMP: EXTENDED DETENTION BASINS
High-Water
Line
8
Z FLOW
3 .C O CO
"TrccSTShrubs
Consideratkins
5o//s
C^rea Required^
Slope
Water Availability
Aesthetics
C^^^^draulh H^d^
Environmental Side
Effects
DESCRIPTION
Extended detention basins are dry between stbrms. During a storm the basin fiUs. A bottom
outiet releases the stoim water slowly to provide time for sediments to setde.
EXPERIENCE IN CALIFORNU
There are no known basins in CaUfomia. Hydraulic detention basins may function Uke
extended detention basins if die fonner has been sized to conuol die pre-development 2-
year event More liberal standards do not provide suffident detention time.
SELECTION CRITERU
• Objective is to remove only particulate pollutants.
• Use where lack of water prevents tbe use of wel ponds, wedands or btofilters.
• Use where wet ponds or wedands would cause unacceptable mosquito conditions.
LIMITATIONS
May be kss reliable than other treatment control BMPs.
InabiUty to vegetate banks and bottom may result in erosion and resuspension.
Limitation of tbe orifice diameter may preclude use in smaU watersheds.
Requires differential elevation between inlet and oudet
Pending dieir volume and depth basin designs may require approval from State
Division of Safety of Dams.
DESIGN AND SIZING CONSIDERATIONS
Basin volume is sized to capture a particular fraction of tbe runoff.
Drawdown time of 24 to 40 houis.
ShaUow basin with large suiface area perfonns better than deep basin wilh same
volume.
Place energy dissipators at die enttance to minimize bottom erosion and resuspension.
Vegetate side slopes and bottom to tbe maximum extent practical.
If side erosion is particularly severe, consider paving OT soil stabilization.
If floatables are a problem, protect outkl widi trash rack or odier device.
Provide bypass OT pass through capabiUtks fw 100 year storm.
CONSTRUCnON/INSPECnON CONSIDERATIONS
• Make sure the outkt is instaUed as designed.
Targeted Constituents
9 Sediment
Q Nutrients
Q Heavy Metals
9 Toxh Materials
Q Fhatable Materials
O Oxygen Demand-
ing Substances
O OfV & Grease
O Bacteria & Viruses
W Ukely to Have
Significant Impact
O Probable Low or Unknown Impact
Implementation
Requirements
^ Capital Costs
O O&M Costs
O Maintenance
O Training
High O Low
TCS
Best^
Management
Practices'^
Industrial Handbook 5 - 40 March, 1993
BMP: EXTENDED DETENTION BASINS (Continue)
MAINTENANCE REQUIREMENTS
Check oudet regulariy for ctogging.
Check banks and bottom of sor&ce basin fOT erosion and correct as necessary.
Remove sediment wbcn accumulation reaches 6-Lncbes, OT if resu^iension is ol)served.
COST CONSIDERATIONS
• GeneraUy kss expensive than wel ponds and wetiands, but more expensive dian btofUlers.
Industrial Ebndbook 5-41 March, 1993
Additional Information — Extended Detention Basins
Extended detention ponds and vaults may be particularly appropriate to Califomia where dry weather base flow cannot
be used to maintain water levels, as is required for wet ponds and constmcted wetlands. These systems are suitable fOT
essentiaUy any size tributary area from an individual commerdal development to a large residential area. Surface ponds
are less expensive to constmct but underground vaults may be appropriate in commercial developments. Use of
concrete retaining waUs wiU reduce the space required by a pond. Tbe basic elements of an extended detention basin
are iUustrated in Hgure 5A. The configuration shown in Figure 5A is most appropriate for large sites.
Extended detention provides a lower removal efficiency than wel ponds and constmcted wetlands: the faciUties are
smaUer diereby reducing their effectiveness with particulate poUutants, and they do not have the abUity to remove
dissolved contaminants. Also, extended detention fadUties may be less reliable than constracted wetlands OT wet ponds
because of tbe lack of a permanent water pool (See Figure SA). But if desired, a shallow pool of 1 to 3 feet could be
included in die design but this is more of an aesthetic consideration. If irrigation water is avaikdile, a diick grass turf on
the bottom of the faciUty may provide someVemoval of dissolved contaminants, like a vegetated biofilter. See TC4
Biofiiters fOT recommendations on ttirf grass and groundcover spedes.
Where irrigation water is not avaUable, there may be concems aboul erosion and resuspension of particulate poUutants
in surface ponds. This, however, has not been a significant problem m Austin, Texas where sand filteis are preceded by
dry settUng ponds (Hartigan, pers. comm.). However, tbe design must incorporate several feabires to nunimize die
potential fOT this problem. Drought tolerant vegetation may work bul has not been evaluated. Nonvegetative materials
may help such as concrete OT plastic grids, smaU riprap, erosion matting, OT paving. A paved forebay may facUitate
maintenance thereby reducing die material avaUable for resuspension.
The recommended drawdown time of 24 to 40 hours for a full pond is based on very limited laboratory data. A few
extended detention ponds bave been monitored and generaUy provide a removal effidency of 60 to 80% with a
drawdown time of aboul 24 houis. Forty hours is recommended in order to settie oul die finer clay particles in Califor-
nia sediment that typicaUy adsorb toxic pollutants.
Design
Determine the volume of die basin usmg die appropriate figure from Appendix D. The procedure is as foUows: (1)
select the appropriate figure fOT your area; (2) determine for tbe catchment thc pcrcenttige of impervious area direcdy
connected to the stoim drain system; (3) choose a capture goal, and read the required unit volume required for the
basin; and (4) multiply this unit volume times the total acreage of the catchment and convert to cubic feet This volume
is also referred to as water quality capture volume shown in Hgure 5A. Total impervious acres may be used in Ueu of
direcdy connected impervious acres if it is easier to determine the fonner, aldiougb dus wiU result in a larger fadUty.
Although diese variations are not equivaknt, diey are reasonable given the uncertainty of die methodology and ex-
pected basin performance.
What should be the capture goal? To achieve an equivalent poUutant capture percentage as a wet pond, 85 to 95
perceni of tbe runoff must be cj^tured and detained. Bul capmre volumes over 85 percent are not cost effective as die
capbire cases in Appendix D show. Therefore it is recommended dial a capture volume of 85 percent be used fOT
determining die detention basin size required. Because of die possibiUty of resuspension of materials duiing extreme
stoims consideration should be given to pladng die basin off line, that is,.it should have a bypass for tbe extreme
events. Bypassing larger events wiU also aUow die bedload carried by die storm and is necessary COT beach replenish-
ment to move downstream.
A drawdown time of 40 hours is recommended in order to settle oul tbe finer clay particles as stated above; however,
24 hours can be used if it can be demonstrated dial tiiis rate wUl remove 80% of the soUds. The analysis of mnoff usinjg
TCS
Industrial Ebndbook 5 • 42 March, 1993
Additional Information — Extended Detention Basins
the hydrologk model STORM and CaUfomia predpitation data found lhal increasing tbe drawdown time from 24 to 40
hours increased tbe size of the basin by only about 10% to 20% depemfing on the location (see Appendix D).
Proper hydrauUc design of the outiet is critical to achieving good performance of die detention basin. The two most
common oudet problems that occur are: 1) the capadty of tbe ouikl is too great resulting in partial filling of die basin
and kss than designed fOT drawdown time and 2) die outiet ctogs because il is not adequately prottxted against trash and
debris. To avoid diesc problems, two altemative oudet types are recommended for use: 1) V-notcb wier, and 2) perfo-
rated riser. The V-noich wier wiU not clog, but il is also difficult to maintain smaU release rates at low heads. The
perforated riser if jsoperiy designed and gravel packed gives much belter control and is recommended over the V-notcb
wier.
Two differeni approaches can be used to control die outflow. One is to use a single orifice outkt widi or without die
protection of a riser pipe. The other is to use die perforated riser itself fOT discbarge control. Bodi approaches arc
presented bdow. *
Row ConttDl Using a .Single Orifice
The oudet conttol orifice should be sized usmg die foUowing equation (GKY, 1989).
a = 2A(H-Ho)0-5 = (7xlO-5)ArH-Ho)0-^
3600CT(2g)0-5 CT (1)
where: a = area of orifice (ft^)
A = average surface area of die pond (ft2)
c = orifice coeffident
T = drawdown time of fuU pond (hrs.)
g = gravity (32.2 ft/scc2)
H = ekvation when the pond is fiiU (ft)
HQ = final elevation when pond is empty (ft)
With a drawdown time of 40 hours tbe equation becomes:
a = (1.75X10-<S)A(H-Ho)0-^
C (2)
Assuming an average release rate at ooe half the pond depth, a common approach in several design manuals, leads to
coosideraUe enor. If the pond has a significant variation of surface area widi depth, do not use Equatton (2); consult
GKY (1989).
Care must be taken in die selection of "c": 0.60 is most often recommended and used. However, based on acmal tests
GKY (1989) recommends die foUowing:
c = 0.66 fOT diin materials, thai is, the tbkkness b equal to OT kss lhan orifice diameter
c= 0.80 when die material is diicker dian die orifice diaoieter
Drilling die oifke into an oudel structure that is made of concrete can result in considerable impact on die coeffident, as
does die beveUng of die edge. The experiments by GKY (1989) were wilh sharp edged orifices.
Industrial Handbook 5-43 March, 1993
Additional Information — Extended Detention Basins
Equation (1) defines the orifice area where a single orifice outiet is used to regulate tbe detention basin outflow. How-
ever, a recent survey of extended detention faciUties (GalU, peis. comm.) found die drawdown time of smaU stoims dial
do not fdl die fadUty to be too short to provide effective treattnent Tbe faciUties surveyed were designed for a draw-
down time 24 hours. A 40 hour drawdown may provide suffident time fOT the smaUer storms. But it may be pmdent
to take additiooal steps to be certain that die smaU storms, which represent tbe majority of pollutton, are effectively
treated. One approach would be to check the design analysis to determine if the faciUty takes at least 24 hours to drain
when half fuU. ff not, either modify the design to achieve this objective, OT instaU a two orifice oudet The lower oudel
is sized to drain a half-fuU faciUty in 24 hours. The second orifice is placed al die mid-water elevation and is sized in
ctxnbinatioo witb die tower orifice to drain die entire friciUty in 40 hours. Anodier ^iproach is to mstaU the outiet about
one fool above the bottom of the pond (essentiaUy enlarging die micropool area). This lower area wiU dry up between
stoims and wiU capture much of the volume of smaU slOTms and improving poUutant removal.
Three altemative outiet stmctures are suggest (Hgure 5B). The concrete block stmcture is appropriate fOT large ponds.
Tbe riser pipe is suggested fOT small to large ponds. Pladng die outiet control in the berm OT in a manhole located
downstream of the fadUty is most suitable for smaU ponds.
Recommendations regarding tbe design of a riser pipe are shown in Table 5 A fOT Austin (1988). Table 5A provides
guidance on tbe location of hoks. To prevent dogging of this orifice and die bottom orifices of die riser pipe, wrap die
bottom three rows of orifices widi geotextik fabric and a cone of one to three inch rock. Tbe boles in tbe riser pipe
should not be modified to achkve a 40 hour drawdown time. Radier, the connnl orifice should he placed downstream.
FOT smaU faciUties, place die control orifice in a manhole between the pond and the filter as shown in Figure 5B. Use a
"T-pipe" (Figure 5B) to submerge die orifice.
TABLE 5A PERFORATED OUTLET RISER PIPE ORIFICES (Austin, 1988)
VERTICAL
SPACING
RISER PIPE BETWEEN ROWS NUMBER OF
DL«kMETER (center to center) PERFORMATEONS
6 in.
Sin.
10 in.
2J in.
2Jin.
2 Jin.
9 per row
12
16
PERFORATION
DIAMETER
lin.
1 in.
lin.
Qogging of die bottom holes has been observed in riser pipes in the mid-Atlantic states (MWCOG, 1992) suggesding dial
die diameter of die riser holes sbouW not be kss dian 3/4 to I" (MWCOG, 1992) altiiough a minimum diameter of 2" is
now being considered (Galli, pers comm.). However, most of die faciUties surveyed had risers widiout die gravel cone
and die oudel holes were modified to provide drawdown control. Modifying tbe holes in the riser to control die oudel
rate reduces the diameter of the holes and increases the risk of clogging. However, gravel packing tbe riser pipe as shown
in Hgure 5B.2 and 5C.1 wiU minimize this risk. Submerging die control orifice as shown in Hgure 5B3 wUl aUow die
use of a smaUer orifice diameter. One orifice wilh a diameter of 1/2 inch, OT 1 inch to be conservative, aUows die use of
extended detention for very smaU catebments. Detention facUities in westem Washington use diis concept and have nol
experienced clogging problems.
How Conttol Using die Perforated Riser
Fbr outkt conbol using die perforated riser as the outflow control, it is recoinmended dial die procedure developed by die
Denver Urban Drainage and Hood Conttol Disttict be used (UDFCD, 1992) as Ulusttated in Figures 5C and 5D. Figure
5D uses a valve fOT C^ of 0.65. Ibis design incorporates flow conttol for the smaU stoims m die perforated riser but also,
provides an ovcrftow outkl for large stonns. If properiy designed, the faciUty can be used fw bodi water quality and
Industriai Handtiook 5-44 March, 1993
Additional Information — Extended D^ention Basins
drainage control by. 1) sizing die perforated riser as indicated fOT water quaUty conttol; 2) sizing tbe outiet pipe to
contrd peak outflow rate frxxn die 2 year storm; and 3) using a spUlway in die pond benn to control die discharge from
larger strams up to lbe 100 year storm.
Odier Design Considerarinns
Do not locate on fiU sites OT on or near steep slopes if is expected dial much ofthe water wUl exit dtfough die bottom,
OT modify tbe bottOTn to prevent excessive infUtration.
Energy dissipation at the miei to minimize erosion
Vegetate the slopes and boOOTn fOT die same reason
Freeboard of 1 foot
Side stopes of at kast 2:1 unless vertical retaining walls are used
Incorporate bypass or overflow for large events
Provide dedicated access to die basin bottCMn (minimum 4:1) fOT maintenance vehicles
Widi a riser stmcture, include an anti-vortex device and a debris barrkr.
Maintenanrft
Condua inspectkiBS scmiannuaUy and after each significant storm. Remove floatables and correct erosion problems in
die pond slopes and booom. Pay particular attention to die oudel control otifice(s) for signs of clogging, ff die orifice is
located in a Type 2 catt:fa basin, remove sediments if tiiey are widiin 18 in. of die csrifice plate. Often extended detention
basin serve multipk used, c.g. basebaU fieW, resulting in higher maintenance costs.
REFERENCES
Austin (City erf), 1988, "Environmental Criteria Manual".
GaUi, J., pers. comm., MetropoUtan Washington Coundl of Governments.
GKY, 1989, "Oudet HydrauUcs of Extended Detention FadUties", for tbe Northem Virginia Planning Disttict Conunis-
sion.
Hartigan, P., pers. cooim., Washmgum Department of Ecology (formerly widi die Cily of Austin).
MettopoUtan Washmgton CouncU of Govemments (MWCOG), March, 1992, "A Current Assessment of Uriian Besl
Managemeni Practices: Techniques fOT Reducing Nonpoint Source PoUution in die Coastal Zone".
MettopoUtan Washingtt)n Coundl of Govemments (MWCOG), 1983, "Nationwide Urtjan Runoff Program PoUution
Removal C^iabUify of Urtian Best Management Practices m die Washington MettopoUtan Area", avaUabk from NTIS
PB84-245497.
Northem Virginia Manning Disttirt Conunission (NVPDQ, 1987, "BMP Handbook for die Occoquan Watershed".
RandaU, C.W., ct al., 1982, "Urtian Runoff PoUutant Removal by Sedimentation", in Proceedmgs of die Conference on
Stt)nnwatcr Detention FaciUties, HennUcer, NH, ASCE, pp 205-209.
Urban Drainage & Ftood Conttol District, Denver Colorado, "Uriian Slorm Drainage Criteria Manual - Volume 3 - Best
Management Practices - Stormwater Quality", Sqitember, 1992.
Whipple, W. and J. Hunter, 1981, "SettkabUity of Urijan Runoff PoUution", J. Water PoUution Conttol Federation, 53
(12): 1726-1731.
Industrial Handbook 5-45 March, 1993
5^ a 6
tr E a
Side Slopes No Sleeper lhan 4:1
n sr
Embankment Side Slope
No Sleeper lhan 3:1
Forebay
InOow —•
FkiW^
Dispersing
Intel
Solid Driving
Surface
Frequent
Hunoll Root
10%lo25V.o( WQCV
Emeroency Spillway Flood
Levet
NOT TO SCALE
Water Quality Capture
Volume (WQCV) level ^ c ^ . i, I J. nno, JJ-.- I / @ Spillway Crest (inciuding 20% additional/ (o.g lOO-yr]
volyme for sediment /
storage) ,/ _ /Spillway Crest
liiverl I
Lov* Ftow
Channel
1.5'to 3' })
SECTION
NOT TO SCALE
Outlet Wollts
(See Figure SB.3 or 5C)
(Used By Permission, UDFCD. 1992)
FIGURE 5A. PLAN AND SECTION OF AN KXTENDICI)
DETENTION BASIN
>
Q.
9*.
o'
BL
K o
3
n>
§.
&
O
a
m §. o a
Additional Information — Extended D^ention Basins
RGURE 5B. 1 CONCHETE STRUCTURE
_ JZ. _______
7|"*—Emergency Spillway '
;! (If Applicable)
^ Flood Control Outiets
10 or 25 Year Outlet
• 2 Year Outiet
Extended
Side View
Detention Outlet
From View
RGURE 53.2 RISER PIPE
uiraacvo Cao
(Used By Pennission, UDFCD. 1992)
/
Design into Impoundment as
Flood Control Spillway
Gravel
Envelope
(recommended)
(See Table 5A)
m m
m
;v*;..*-.j
I.-..-.^'
^!
i
Control
• Orifice Plate
Control Structurs
Emergency Overflow W.
Pond Design W.S.-cr
RGURE 5B.3 CONTROL MANHOLE
Flood Control Outiet
Source: Douglas County, Colorado
0«bris Barrier
Berm Embankment
-Contrd Orifice Plata
FIGURE 5B. OUTLET CONFIGURATIONS USING
SINGLE ORIFICE FOR FLOW CONTROL
Industrial Handbook 5-47 March, 1993
Additional Information — Extended D^ention Basins
Thraadad Cao
Rarncvaow & Locxaol*
Cvsrtlow Grata for
Larcsr Storms
Watar Qualitv
Risar Pipa (Saa Oatail)
Notas: 1. Tha ouSat pip* stuR ba sizad to conirol
overflow into tm concrata risar.
2. Altematt dasi^ns indud* a HyfittQbraka oudet (or onfica dasignt) as long as t\m hydraulic
perlormanca matches ffvs
oonfiguration. OUTLET WORKS
NOT TQ SCAI.C
Siza Base to Pravant
Hydrostatc Uplift
Notas: 1. Minimum numbar of hdas • 8
2. Minimum hola diamatar • 1/S* (fia.
1-1/2* diameter Air
Vent in Threaded Cap
Watar Otjamy
Outlat Holes
Ouctila Iron or
Steal Pipe
WATER OUALfTY
RISER PIPE
NOTTOSCALS"
(Used By Pemnission. UDFCD, 1992)
FIGURE 5C
Maximum Numbar ol Pertoratad Columns
Risar
Oiametar Hole Oiametar. in.
f«n.) 1/4* 1/r 3/4-1*
4 --
6 -
8 IS 16 12 S
10 20 20 14 to
12 24 18 IZ
Hole Oiametar
On.) Araa of Hole
(in.2)
1/8
1/4
3m
1/2 sm
3/4 7m
1
0J13
0.110
0.196
0J07
0.442
0.601
0.7S5
OUTLET CONFIGURATION USING
PERFORATED RISER FOR FLOW
CONTROL
Industrial Handbook 5-48 March, 1993
Additional Information — Extended D^entlon Basins
0.02 0.04 0.06 0.10 0.20 0.40 0.60 1.0 2.0 4.0 6.0
Required Araa p«r Row (in,^)
(Used By Pennission, UDFCD, 1992)
FIGURE 5D. WATER QUALITY OUTLET SIZING:
EXTENDED DETENTION BASIN WITH
A 40-HOUR DRAIN TIME OF THE
CAPTURE VOLUME
Industrial Handbook 5-49 March, 1993
BMP: MEDIA FILTRATION
FLOW PRETTIEATMENT
Considerations
Soils
Area Required
Shpe
Water Availability
Aestheths
<CH^raulh He^^
Environmental Side
Effects
DESCRIPTION »
Consists of a settling basin foUowed by a filter. Tbe most common filter media is sand;
stsne use peat/sand mixture.
EXPERIENCE IN CALIFORNIA
• A tenant at tbe Pon of Lcmg Beacb recentiy installed a sand fdter. Tbe City of Los
Angeles will soon install several experimental filters.
SELECTION CRITERIA
• Objective is to remove only sediment (paniculate pollutants).
• Use wbeie unavailability of water prevents tbe use of wet ponds, wetlands, or
biofiiters.
• Can be placed underground.
• Suitable for individual develo{Hnenis and small tributaiy areas up to aboul 100 acres.
• May require less space tban otber treatment conttol BMPs.
LIMITATIONS
• Filter may require more frequent maintenance dian most of lbe otber BMPs.
Headloss.
• Dissolved pollutants are not cultured by sand.
• Severe clogging potential if exposed soil surfaces exist upstteam.
DESIGN AND SIZING CONSIDERATIONS
• Settling basin smaller tban wet or extended detention basin.
• Spread flow across filter.
• Place filter offline to protect firom extreme events.
• Minimize erosion in settling basin.
CONSTRUCTION/INSPECTION CONSIDERATIONS
• Be certain filter sand is clean and die oudet device &om tbe basin to die filter is level.
MAINTENANCE REQUIREMENTS
• Clean filter suiface aboul twice annually; or more often if watershed is excessively
erosive.
COST CONSIDERATIONS
• Filtration system may use kss space tban odier systems.
• Smaller media improves perfonnance but increases maintenance costs.
Targeted Constituents
% Sediment
O Nutrients
O Heavy Metals
O Toxh Materials
9 Fhatable Materials
O Oxygen Demand-
ing Substances
O OiV & Grease
9 Bacteria & Viruses
W Ukely to Have
Significant Impact
O Prol>able Low or
Unknown Impact
Implementation
Requirements
# Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
TC6
Best^
Management
Practices>
Industrial Handbook 5-50 March, 1993
Additional Information — Media nitration
Sand filters may be particularly suitable for industrial sites because the settling basin can be located undergnjund. A
sand filter consists of two units: sealing basin and tbe filter. Pretreattnenl is essential to avoid rapid clogging of tbe
fdter. Peat/sand oiixture has been used: peat having die ability to remove dissolved contaminants. However, tiiere have
been clogging probkms (Tomasak, el al., 1987) bul diis may be due to using die wrong type of peat (Galli, 1990).
Limited research indicates lhat compost made from leaves is very effective at removing dissolved pbosphoius and
metals, and oil and grease (Stewart, 1989). A new concept is placemenl of a fdter device in a catch basin insert
(McPherson, 1992) which may be very well suited for industiial sites.
Field research in tbe City of Austin, Texas (Austin, 1990) indicates the sand filter has a removal efficiency of suspended
solids dial is similar to wet ponds and extended detention: 70 to 90%. Tbe observed removal of metals was 20 to 80%,
depenUng on the metal, 20 to 30% for nitrogen, and 50 to 60% for phosphorus. These rates are also similar to wet
ponds, which is not expected as a filter does not remove dissolved contaminants. Sand witb a diameter smaller than used
in Austin would likely improve perfoimance bdl has not been tried.
Tbe sand filter should be an ideal system for die Central Valley and Southem California. It does not rely on vegetation,
and has proven itself in the City of Austin. Tbe sand filter is siutable for tributtuy areas of a less dian an acre to about 50
acres.
Make certain that any soil erosion problems in die site have been corrected (Chapter 4). Experience in Austin indicates
thai exposed soils during construction "upstream" fiom die filler can result in penttation of fines inttJ the filter media,
resulting in a need to replace die entire filter bed. The system should bave a bypass for extreme events.
Alternative confiytirarion.s
Tbe most experience to date is with surface facilities shown conceptually in Figure 6A. It can be used on catchments up
to perhaps 50 acres. Its origin is Austin, Texas where there are now several hundred fecilities. The "Austin" filter uses
an extended detention basin wilh a drawdown time of 24 hours. Two other systems are most suitable for small
catchments ofa few acres. An underground "linear" filter (Figure 6B) is used in Delaware (Shaver, 1991). The filter
accqits sheet flow firom adjacent pavement IL therefore, may be ideal for industrial applications. Anodier underground
design (Figure 60 developed in Wasbingttm D.C. (Tniong, 1989) is also ideal for developments. Il accepts concen-
trated flow. Bodi of these underground systems use a wet vault (or water quality mlet, see TC7) as die pretreattnenl
device. Tbe fourth concept is (Hgure 6D) is an insert placed in existing cateh basins. Il should only be used where
maintenance staff are available to check die filter frequentiy and where local flooding will not txcur if tiie filter clogs.
Determining tiie volume of die pretreatment nnit
To size tiie pretreatment basin refer to die sizing mediods for extended detention (TC5). With die sand fdter die pre-
treatment basin need not be as efficienl as a full size systeoL The pretreatment system, however, should be large enough
to provide a removal effickncy dial avoids rapid clogging of die fdter. As yet, diere is no clear answer on diis question.
For now it is suggested that die volume of a wet vaull be such as to achieve a removal efficiency of 50 to 60%.
The volume of an pretteatmeni unil can be decreased by reducing die drawdown lime, which results in a lower bul
acceptabk removal effickncy. Tbe facility volume can be determined from TC5 Extended Detention using a drawdown
time of 24 hours.
Industrial Handbook 5-51 March, 1993
Additional Information — Media nitration
Detennining the surface area of die filter
The following equation is derived from Austin (1988) for a maximum (fiill pretreatment basin) filtration time of 24
hours:
Fdter area (fl2) = 3630SuAH/K(D+H) (1)
where: Su = unil storage (inches-acre) fiom Appendix D
A = area in acres draining to facility
H = deptii (ft) of die sand filler
D = average water depth (ft) over the filter taken tt) be one-haffthe difference between die top of die filter
and die maximum water surface ekvation
K = filter coefficient recommended as 3.5 (Austin)
i
Equation (1) is appropriate for die filter media size recommended by die City of Austiin, diameter of 0.02 to 0.04 inches.
The filter area must be inaeased if a smaller media is used (see Austin, Texas (1988)).
Configuring a surface sand filter (City of Austin concept)
Additional design criteria for die settling basin (Austin, 1988):
For tbe oudel use a perforated riser pipe, as described in TC5, Extended Detention
Size tbe outkt orifice for a 24 hour drawdown
Energy dissipabx* al the inlet to die settling basin
Trash rack at oudets to the filter
Vegetate slopes to die exteni possible (see Vegetated Biofiiters)
Access ramp (4:1 or less) for maLntenance vehicles
One foot of fineeboaid
Lengdi to width ratio of at least 3:1 and preferably 5:1
Sedunent trap al inlet to reduce resuspension. One concept is shown in Figure 6E.
Additional design criteria for the filter
Use a flow spreader (Figure 6A).
Use either of two altemative sand bed designs (Figure 6F).
Use clean sand 0.02 to 0.04 inch diameter.
Some have placed geofabrk on sand surface to facilitate maintenance.
Underdrains (Figure 6A).
- Scheduk 40 PVC.
4 inch diameter.
3/8 inch perforations placed around tbe pipe, with 6 inch space between each perforation cluster,
maximum 10 foot spacing between laterals.
- minimum grade of 1/8" per foot
Configuring die linear filter
Take die volume for tbe pretreattnenl unil and die filter area identified above and configure into a stmcture similar to dial
shown in Figure 6B. Tbe structural design in Figure 6B assumes traffic loads over die filter. The sttucture can be kss
robust if il is located along tbe edge of die pavement away Crom traffic. Other recooimendations (Shaver, 1991):
Industrial Handbook 5-52 March, 1993
Additional Information Media nitration
• Depdi of sand 18"
Diameier of die oudet pipe should be 6" or less; use multiple outiets if necessary
The filter must be positioned relative to tbe pavement in a manner tiiat evenly distributes die flow as il enters tiie
sedimentation chamber. Pavement design and constmction is therefore critical.
Confignrinp die wet vault filtpr
Similarly die volume of tiie wet vault and fdter area are configured into a rectangular unit similar to tiiat shown in Figure
6C. Otber considerations for tbe wet vault include:
• A length to width ratio of at kast 3:1 to nunimize sbon-circuiting
• Baffles to reduce entrance velocities and tq retain floatables
• Access ports to facilitate maintenance
• Depth of die wet pool of at least 3 feet but nol more dian 10 feel
Catch hasin in«;prt
The catt± basin insert filtta- may be ideal for industtial sites as it can be placed in existing catch basins, and tiierefore
may avoid tiic need for an "end-of-pipe" facility. The system is illusttated in Figure 6D. It consists of a scries of ttays.
The ttip ttay is a sediment trap. Fdter material is placed in die lower ttays. Of several materials examined, die most
suitabk ^ipears lo be household fiberglass insulation. Linuted tests indicate over 90% removal of metals and oU
(McPherson, 1992). As die insert requues fiequeni attention it should only be used where a maintenance person is
located on-site. The insert has a bypass along one side should die filter nutterial clog and is hydraulicaUy designed so as
u> not compromise die primaiy purpose of a catch basin, K> get stonn water into die drain system. The concept shown in
Figure 6D is proprietary (Enviro-drain, 1992).
Mainlpnanr^
Inspea semiannually, and after major stonns. Sediment should be removed firom die settiing basin when 4 inches
accumulates and fiom die fdter wben 1/2 inch accumulates, or when diere is stiU wafer Ln die basin or over die filter 40
bours after die stonn. Remove floatables. Experience in Austin indicates die filter surface must be cleaned aboul twice
each year by raking off die dried sediment Failure to clean die fdter regularly may result in die need to replace the
entire media because of penettation of fmes inttj die ater. It is more cost effective over die long term to clean tiie fdter
regularly as recommended, ff diere are open space areas in die ttibutary dial are erosive or if consttuction ts occumng,
more fiequeni cleaning wiU be necessary. It may be necessary to replace tbe fdter media afua- consttuction activity has
ceased and tbe soils are stabilized.
Consult Austin (1988). Tmong (1989), and Shaver (1991) for additional design and maintenance criteria.
REFERENCES
Austin (City oO. 1990, "Removal Efficiencies of Sttjnnwater Conttol Sttucttires".
Austin (City oO, 1988, "Environmental Criteria Manual".
Envinvdrain Inc, 1992, Kirkland. Washington.
Galli, J., 1990, "Peat-Sand Fdters: A Proposed Sttmnwater Managemeni Practice for Urtianized Areas", MettopoUtan
Washington Council of Govemments.
VfcPherson, J., 1992, "Water Quality BMPs: Catt± Basin Infilttation", presented to the APWA
Sttxmwater Managers Committee, Tacoma, Washington.
Industrial Handbook 5-53 March, 1993
Additional Information — Media pntration
Mettropolitan Wasbington Council of Governments (MWCOG), March, 1992, "A Current Assessment of Urban Best
Management Practices: Techniques for Reducing Nonpoint Source Pollution in the Coastal Zone".
Shaver, E., 1991, "Sand Fdter Design for Water Quality Treattnent", Delaware Departtnent of Nattiral Resources.
Stewaa W., 1989, "Evaluation and Full-Scale Testing of a Compost Biofilter for Stormwater Runoff Treatment",
presented at the Annual Conference of die Pacific Ncaibwest Pollution Control Association.
Tomasak, MJD., G.R Johnson, and PJ. Mulloy, 1987, "Operational Probkms with a Soil Fdtration System for Treating
Stoimwatei", Minnesota PoUution Conttol Agency.
Tmong, H. V., 1989, "Tbe Sand Filter Quality Stmcture", Disttia of Columbia Govemment
Industrial Handbook 5-54 March, 1993
5* a.
9 CL
r
tn
ti
n
'fi
PLAN VIEW
f-illralion Basin
Energy Dissipalors
Pretreatment [o
\
Stormwater Cliannel
Drop Inlet
^ i"" r' r
• • ' • ' '
:i 'I 'I
II I I I •
I I 1 I I 1 I I I I I I • I I I
1 ' • '
: 'J: |
in—p-
A
Weir To Achieve
Filtered Outllow
Stone
nip Rap
Uniform Discharge
iMilril««iili mm
vnt*
-Sand Bed —
ELEVATION t Underdrain Piping System
Source: City of Austin
FIGURE 6A. CITY OF AUSTIN SAND FILTER
> a.
Q.
S o
W
ET —*% o —%
3 o>
o'
3
S.
S'
cr. o a
Additional Information — Media Filtration
.T.0W r •.V
GXATEDCOVES. SOLIDCOVER
DRAIN
Ot-TrAU.
Ftow
1 • •_ •
% • 1
•
SA.NT)
PAVTNG
OtTFALL
SECTION A-A
GRATE (TAB5UC WTIAPPED
OVER E>'TIR£ CRATE OPE>1NC)
Source: Shaver (199D
El^fTRANCE
GROUND
FIGURE 6B. LINEAL SAND FILTER
LA00E.=1 y ENTBANCE
9\J
ENTRANCE
•r.r...-n:-:-Ml ... > ' • • -
/
'-h^jrX'-^ tr
•WASHED SAND--'
OiWiTT^lN'
AGGREGATE ^ CtEAN OUT PIPE
Source: District of Columbia
FIGURE 6C. VAULT SAND FILTER
Industrial Handbook 5-56 March, 1993
Additional Information — Media Filiation
Catch Basin Grate
Sediment Trap
Filter Trays
Insert Box \ rv_
Source: McPherson (1992)
FIGURE 6D. CATCH BASIN FILTER
Industrial Handbook 5-57 March, 1993
Additional Information — Media Ritration
Sediment Trap Drain Pips
Drop inlet
Bottom of
Sedimentation
Basin
10
- Outiet
Structure
Section A - A
(Gravel Not Shown)
Sediment Trap
'iri-r-^ To Outlet Structure
2" Gravel Layer Perforated PVC Pipe B. SEDIMENT TRAP
Over Pipe Wrapped in Geotextile Fabric
Source: City of Austin
FIGURE 6E. EXAMPLE RISER PIPE AND SEDIMENT TRAP DETAILS
Industrial Handbook 5-58 March, 1993
Additional Information — Media Rtration
Sand Bed
18" Min.
Geotextile Fabric Perforated PVC Pipes
A. SAND BED PRORLE (WITH GRAVEL LAYER)
4" Perforated PVC Pipe
Covered with Geotextile Fabric
18" Min.
Sand Bed
1"To2"
Gravel Layer
Max. Slope 4:1 Geotextile
Fabric
•Max. 10'-0" O.C.
12" Min.
B. SAND BED PRORLE (TRENCH DESIGN)
Adapted from City of Austin (1989)
FIGURE 6F. SAND BED FILTRATION CONFIGURATIONS
Industrial Handtiook 5-59 March, 1993
BMP: OIUWATER SEPARATORS AND WATER QUALITY INLETS
FLOW
Considerations
Soils
C^^Area Requir^^
Shpe
Water Availability
Aesthetics
Hydraulh Head
Environmental SkJe
Effects
DESCRIPTION ,
Oil/water separators are designed to remove one specific group of contaminants: pettoleum
compounds and grease. However, separators wiU also remove floatable debris and settie-
able solids. Two general types of (Ml/water separators are used: conventional gravity
separator and tbe coakscing plate interceptor (CPI).
EXPERIENCE IN CALIFORNIA
Oil/water separators are in use throughout California al industrial sites. OU/water separa-
tors are used at all bulk petroleum storage and refinery facilities. A few jurisdictions
require new commercial developments to install separators under certain situations dial are
environmentaUy sensitive.
SELECTION CRITEIUA
Applicabk tt> situations where tiie concentration of oU and grease related compounds wiU
be abnonnally high and source controi cannot provide effective control. The general types
of businesses where diis situation is likely are truck, car, and equipment maintenance and
washing businesses, as weU as a business that performs maintenance on its own equipment
and vebicles. PubUc facilitks where separators may be required include marine ports,
airfields, fleet vehicle maintenance and washing, facilities, and mass transit park-and-ride
lots. Conventional separators are capable of removing oil droplets witb diameteis equal to
or greater tban 150 microns. A CPI separator should be used if smaUer droplets must be
removed.
LIMHATIONS
• Littie data oo oU characteristics in storm water leads to considerable uncertainty about
performance.
• Air quaUly permit (conditional autiiorization) permil-by-rale from DTSC may be
required.
DESIGN AND SIZING CONSIDERATIONS
• Sizing related to anticipated influent oil concentration, water temperature and velocity,
and die effluent goal. To maintain reasonable separator size, il should be designed to
bypass flows in excess of first flush.
CONSTRUCTION/INSPECTION CONSIDERATIONS
• None identified.
MAINTENANCE REQUIREMENTS
• Ckan fiiequendy of accumulated oil, grease, and floating debris.
COST CONSIDERATIONS
• Coalescing jAate material is costiy but requires less space tiian die conventional
setiarator.
Targeted Constituents
O Sediment
Q Nutrients
O Heavy Metals
O Toxh Materials
% Fhatable Materials
O Oxygen Demand-
ing Substances
# 0/7 & Grease
O Bacteria & Viruses
# Ukely to Have
Significant Impact
O Probable Low or Unkrtown Impact
Implementation
Requirements
Q Capital Costs
Q O&M Costs
O Maintenance
O Training
High O Low
TO?
Best^
Management
P^actlces^
Industrial Handbook 5-60 March, 1993
Additional Information —• OIIAVater separators and Water Qualrty Inlets
General Tnfnrmarirfn
^^f!!". ^ ^ "^"^ ^ °^ ^'^"^ "=sult in abnonnal amounts of pettokum produ«s lost lo exposed pavement eidier by accidental smaU spUls or nonnai dripping from tiie vehicle
^^«hr^K"" "^'^ ^related to vehicle and mobUe equipment mainten^aclvities. Se^^^s may I
^ be advmbk where an area IS heavily used by mobUe equipment such as loading wharfs at marine poS^JZa
indicates od/water separators can reduce die oU/grease concenttation below 10 mg/l (Lettemnaier, el ai. 1985)
Wet ponds, consttuct«l wedands, and biofilter^ wiU remove pettolemn products bul dieir reliabUity is uncertain where I
^c^^^fl ?products may occur frequendy. Also, BMPs dial rely on vegetation may be damaged or
become unsightiy if high concenttattons of oU and grease occur frequentiy. " or |
upon die rise rak velocity of oU droplet and rate of mnoff. However, witii die exception
^""^ "1"''"'' diere are no daia describing die characteristics of pettokmn product; in urtian stoT
^ " T ^c-^' °" '^'^ ^ ^ rise^ or dirSmeasure^Tof ri^
^Z^t^S^n C^^'-'Jy. the perfonnance of oil/water
Tlebaskconfigurationsofljetwotypesofse^ Witii small instaUations, a conven- I
fSS^ve^ST^ ^ general appearance of a septic tank, bul is much longer in relationship to its^fd^ iSger
facdittes have the appearance ofamuniapalwastewaterprimary sedimentation tank. IHe CPI separator contains dSv
^plates whidi enhances die removal effidency. In effect tt> obtain tiie same effluent quabtyTm s^J^r '
mjmres considerably less space dian a conventional separator. THe angk of die plates tt> die boiSon^ r^S,m 0°
Sn'T^0 7Tu;?^ -stcommon, me per^dicu^distance bet^rifprtes^^f
^l^lffh'^'""" is die water quaUly inkt iUusttated in Figure 7B. It is essentiaUy a conventional gravity separator bul
I^(2^r4S^K of ^- i"""^^ '^'^'^''^ « ^" "^^^ recommended v^u^ tiS^i^iS?.^^^^^^" too small To be effective, a water quality mlet must have die surface area and
^Tb^l ^, conventional separator. Uiey may exhibit odor problems during die summer because of
w ? degradauon of accmnulated organic matter and die lack of reacration of die tet pool Facilities in
but it bas been noticeabk only when tiie ^stem "
j DesigTi of rnnvmrinng| <?rTTfimfrn
The sizing ofa separattw is based upon die calculation of die
(modified fiom API, 1990): rise rate of die oil droplets using die following equation
Vp = 1.79(dp-dc)d2x 10-8/n (1)
where: = rise rate (ft/second)
= absolute viscosity of die water (poises)
= density of die Ml (gm/cc)
= density of die water (gm/cc)
= diameter of die droplet to be removed (nucrons)
TC7
March, 1993
Additional Information — Oll/Water separators and Water Quality Inlets
A water temperature must be assumed to select the appropriate values for water density and viscosity from Table 7A. The
engineer should use the expected temperature of die slorm water during the December-January period. There are no data
on the density of pettoleum products in urban storm water bul it can be expected to Ue between 0.85 and 0.95. To selea
tbe dropkt diameter tbe engineer must identify an efficiency goal based on an understanding of the disttibution of droplet
sizes in sttxm water. However, there is no information on tbe size distribution of oil droplets in urban storm water.
Figure 7C is a size and volume distribution for storm waler from a petroleum products storage faciUty (Branion, undated).
The engineer must also sekcl a design influent concenttation, which carries considerable uncertainly because it wiU vary
widely widiin and belween stonns.
To iUustrate Equation 1: if tbe effluent goal is 10 mg/l and the design influent concenttation is 50 mg/l, a removal
efficiency of 80% is required. From Figure 7C: tiiis efficiency can be achieved by removing aU droplets witii diameters
90 microns or larger. Using a water temperature of lO^C gives a water density of 0.998. Using an oil density of 0.898,
the rise rate for a 90 micron droplet is O.OOI 1 feet per second.
Il is generaUy beUeved that conventional separators are not effective al removing droplets smaUer than of 150 microns
(API, 1990). ThecveticaUy, a conventional separator can be sized to remove a smaUer droplet but the facility may be so
large as to make the CPI separator more cost-effective.
Sizing conventional separator (modified from API, 1990).
OJ
D= (Q/2V) (2)
where: D = depth, which should be between 3 and 8 feet
Q= design flow rate (cfs)
V = aUowable horizontal velocity which is equal to 15 times the design oU rise rate but not greater than
0.05 feet per second
ff the depth exceeds 8 feet design paralkl units dividing the design flow rate by tbe number of units needed to reach die
maximum recommended deptii of 8 feet Equation (2) is simplified from equations in API (1990) based on a recom-
mended widdi to depth ratio of 2. Tbe constant in Equation (2) can be changed accordingly if a different ratio is as-
sumed. Some engineers may wish to hicrease tbe facility size to accounl for flow turbulence. See API (1990) for die
design procedure.
Then:
Calculate kngdi, L = VD/Vp
Compute widdi, W = Q/(VD). This should be 2 to 3 times die depdi, bul not to exceed 20 feet
Baffle height tti dqMh ratio of 0.85 for ttip baffles and 0.15 for bottom baffles
Locate the distribution baffk at O.IOL from die entrance
Add one foot for freeboard
Install a bypass for flows in excess of the design flow
Detennining tbe design flow, Q, requires identification of the design stonn. Tbe separatcx is expected to operate effec-
tively at aU flow rates equal to or less than die peak mnoff rate of the design storm. Tbe design storm need not be an
extreme event as is typicaUy used in tbe sizing of flood control faciUties. ff sized u> handle a storm fiequency between
thc 3-month to 1-year event die faciUty wiU effectively treat the vast majority of storm water dial occurs over time. AU
events equal lo or less than ttie 6-moodi event represents about 90% of the precipitation over time; designing for a 2-year
Industrial Handtiook 5 - 62 March, 1993
Additional Information — Oil/Water Separators and Water Quality Inlets
event only increases tbe amount of runoff tteated by aboul 5% (increase from 90% to 95% of rainfaU tteated). For die
design storm selected, calculate tbe peak mnoff rate using tbe rational method.
AppUcation of die Conventional Oil/Water SepatT<tnr
Assume diat a conventional oU/waterseparattir is to be used tt) treat ranoff from a 1/2 acre parking lot Assume ftirther it
is tt) be sized to tteat nmtrff from a rainfaU rate of OJO incfaes/hr (which ttanslates to a runoff rate of 0.50 cfs/acre when
tbe area is 100 percent impervious.
Using die example above, die computed Vp is 0.0011 ft/sec. Using Equation 2, V =15 x 0.0011= 0.0165 ft/sec whkh is
less dian 0.05 ft/sec; thus,
D = (Q/2V)0.05 = (1/2 X 0.05/(2 x 0.0165)) x 0.05
D = 3.8ft. '
L = VD/Vp = 0.0165 X 3.8/0.0011
L = 57ft
W = Q/(VD) = 0.25/(0.0165 X 3.8)
W = 4.0 ft since W is less dian 2 x D, increase widtii tt) W = 3.8 x 2 = 7.6 ft
Thus, a conventional oil/water separator sized to capture mnoff from a 0.5 in/hr rainfaU on a 1/2 acre parking loi would
be:
D = 3.8 ft
W = 7.6ft
L = 57 ft
S^7inp^PTyT^f^r?^to^
Manufacturers can provide packaged separator units for flows up to several cubic feet per second. For larger flows, die
engineer must size die plate pack and design die vault Given die great variabUily of separator technology among
manu&cturers with reqiect to plate size, spacing, and incUnation, il is recommended diat die design engineer consult
vendors for a plate package dial wiU meet the engineer's criteria. Manufacttirer's typicaUy identify die capacity of
various standard units. However, die engineer's design criteria musl be comparable to dial used by die manufacturer in
rating its imits.
Tbe engineer can size die facUity using die foUowing procedure. First identify tiie expecuxl plate angle, H (as degrees),
and calculate die U)tal plate area required, A(ft\
A = Q/VpCosineH (3)
CPI separators are not 100% bydrauUcaUy efficient; ranging from 0.35 to 0.95 depending on die plate design (Aquatrend,
undated), ff die engineer wishes to incorporate diis factor, divide die result from Equation 3 by die selected efficiency.
Select spacing, S, between die plates, usuaUy 0.75 to 1.5 inch.
Identify reasonaUe plate width, W, and kngdi, L.
Number of plates, N = A/WL.
Calculate plate volume, Pv(ft^).
Industrial Handbook 5-63 March, 1993
Additional Information — Oll/Water separators and Water Quality Inlets
Pv= (HS+LCosineH)(WLSineH) (4)
12
Add a foot beneadi die plates for sediment storage.
Add 6" to 12" above tbe plates for water clearance so dial die oil accumulates above tbe plates.
Add one fool for freeboard.
Atkl a forebay for floatables and distribution of flow if more tiian one plate unit is needed.
Add after bay for coUection of the effluent from the plate pack area.
For larger units include device to remove and store oU from the water surface.
Horizontal plates require the least plate volume to acbieve a particular removal efficiency. However, settieable soUds wUl
accumulate on tbe plates compUcating maintenance procedures. The plates may be damaged by die weight when
removed for cleaning. The plates should be placed at an angle of 45° to 60° so dial settieable soUds sUde to the facility
botuim. Expeiknce shows dial even with slanted plates some soUds wiU "stick" to die plates because of tbe oU and
grease. Placing tbe plates closer togedier reduces the plate volume. However, if debris is expected such as twigs, plastics,
and paper, selea a larger plate separation distance. Or inslaU ahead of tiie plates a ttash rack and/or screens with a
diameter somewhat smaUer dian die plate spacing.
Recognizing thai an oil/water separattir also removes settieable solids, it can also be considered a wet vault (TC2). Tbe
engineer can use Figure 2B (See TC2) to estimate tiie efficiency of both the conventional and CPI separators. As Figure
2B does not include die effea of plate technology, a CPI separator should perform considerably better dian indicated in
Hgure 2B for the same Vt/V^ ratio.
See API (1990) for further design concepts for both die conventional and CPI scparattirs.
Maintenancg
Check monthly during the wet season and clean several times a year. Always clean in October before tbe start of tbe wet
season. Properiy dispose die oU.
REFERENCES
American Pettoleum Institute (API). 1990, "Design and Operation of Oil-Water Separators", I*ublication 421.
Aquatrend, undated, "Design Manual: Innova Sep Particle Separation System", Shawnee Mission, Kansas.
Branion, R., undated, "Principles for die Separation of OU Drops from Water in (jravity Type Separators", Department of
Chemical Engineering, University of British Columbia.
Lettemnaier, D. and J. Ricbey, 1985, "Operational Assessment of a Coalescing Plate Oil/Water Separator", MunicipaUty
of MetropoUtan Seattie.
MettopoUtan Washington Coundl of Govemments (MWCOG), March, 1992, "A Current Assessment of Urban Besl
Managemeni Practices: Techniques for Reducing Nonpoint Source PoUution in the Coastal Zone".
SUverman, G, 1982, "Wetlands for OU and Grease Control", Tech Memo. 87, Association of Bay Area Govemments.
Industrial Handbook 5-64 March, 1993
Additional Information — on/Water separators and water Quality Inlets
TABLE 7A. WATER VISCOSITIES & DENSIFIES
1
Density of
pure water
Temperature Absolute Viscosity Density in air
•c T (Poises) (slugs/rtsec) (gm/cc) Obs/fp)
0 32.0 0.017921 0.00120424 0.999 62351
1 33.8 0.017343 0.00116338 0.999 62355
2 35.6 0.016728 0.00112407 0.999 62358
3 37.4 0.016191 0.00108799 0.999 62360
4 39.2 0.015674i 0.00105324 1.000 62360
5 41.0 0.015188 0.00102059 0.999 62360
6 42.8 0.014728 0.00098968 0.999 62359
7 44.6 0.014284 0.00095984 0.999 62357
8 .46.4 0.013860 0.00093135 0.999 62354
9 48.2 0.013462 0.0009O460 0.999 62350
10 50.0 0.013077 0.00087873 0.999 62345
11 51.8 0.012713 0.00085427 0.999 62339
12 53.6 0.012363 0.00084870 0.999 62333
13 55.4 0.012028 0.00080824 0.999 62326
14 572 0.011709 0.00078681 0.999 62317
15 59.0 0.011404 0.00076631 0i>99 62309
16 60.8 0.011111 0.00074662 0.999 62299
17 62-6 0.010828 0.00072761 0.999 62289
18 64.4 0.010559 0.00070953 0.999 62278
19 662 0.010299 0.00069206 0.999 62266
20 68.0 0.010050 0.00067533 0.998 62254
Industrial Handbook 5-65 March, 1993
Additional Information — onWater Sep«tors and water Quality Inlets
Clear
well
Oil retentksn Oil seporatkjn Bow cSstributkm
Water
Inspection and
sampling tee
CONVENTIONAL SEPARATOR
Grit/sludge
removal tx3ffle
Adapted from Romano, 1990
Water
outlet
Separator
vault
Coalescing
plates
COALESCING PUVTE SEPARATOR
Water
inlet
now Adapted from Romano, 1990 baffle
FIGURE 7A. CONVENTIONAL AND COALESCING
PLATE SEPARATORS
Industrial Handbook 5 - 66 March, 1993
Additional information —Oil/Water Sep^ators and water Quality Wets
Primary Inlet ^
\
IIIIHIIMM
/ Ma.-inoies
/
Trash Rack Protects
Two 6 Inch Orifices
Inverted Elbow
Pipe Regulates
Water
Levels
f Raised Secondary Inlet
for Large Storms
iiiiiiiimij
Overflow
Pipe
Reinforced
Concrete
Construction
Adapted from Schueler, 1987
NOTE:
1. Size as conventional separator.
2. Design outlet orifice in ettxjw to limit outftow
to the design rate for the unit
FIGURE 7B. WATER QUALITY INLET
Industrial Handbook 5-67 March, 1993
Additional Information — Qn/Water separators and Water Quaiity Inlets
IOOl
2. "S
N (0
CO a
Q. Q. 2 2 o o
is
_2 "5 ^ to > o
Be
_ CD C JZ
a> —
o v.
a. a
CO
Drop Dlam«t«r<mleron)
SIZE
VOLUME
Source: Branion (undated)
FIGURE 7C. SIZE AND VOLUME DISTRIBUTION
Industrial Handbook 5-68 March, 1993
Additional Information — Muitipie-systems
Multiple systems may occur in series or by stacking verticaUy. Multiple systems thai have been tried or that appear to be
feasible are presented below.
Stacked systems
• Extended detention above wet pond* used extensively m the mid-Atianiic states. Recommended by several
{vactioners because of die uncertainly about tbe perfoimance of wel ponds.
• Wet pood above sand fUlen has been tried in Florida and Massachusetts and found wanting due to die clogging of
the sand filter by settieable soUds.
Series systems
* Extended detention basin - sand fUten standard system in Austin, Texas. Settiing basin is needed to avoid excessive
maintenance on tbe sand fUter. ^
• DetentioD basin - sand fUter - wetiand: Large system operating in Florida.
* Wel pond - wetland: where an unusuaUy high loacUng of sediment is expected, a fiiU size wet pood, rather tban just
a forebay in the wetland, may be desirabk to minnnize the amount of sediment reaching the wetland where il would
be more costiy-to remove.
* Biofilter - wet poncL* Used frequentiy in die Pacific Northwest again to enhance reliabiUty.
• Bkifilter - infUtration ttench: treattnent of tiie sttiim water before il enters an infUtration system.
• Oil/water separator - wetland or biofUter oil/water separator used to protea the vegetated treatment system where
high concentrations of oU may frequendy occur.
Industrial Handbook 5-70 March, 1993
BMP: MULTIPLE-SYSTEMS
4. Ftow
INHtTRATION
TRENCH
S
1
INFILTRATION
BASIN
•FLOW
Ck>nsiderat)ons
5o//s
(^^^^aRequi^d^
C^^^^terAvailabii^^
Aestheths
C^d/au//c Head^
^Environmental Side
Effects
DESCRIPTION ,
A multiple tteatment systom uses two or more of tbe preceding BMPs in series. A few
multipk systems have already been described: settling basin combined with a sand filter,
settling basin or Ixofilter combined with an infilttation basin or trench; extended detention
zone on a wet pond.
EXPERIENCE IN CALIFORNU
The research wetlands at Fremont CaUfomia are a combination of wet ponds,
wetlands, and grass biofiiters.
SELECTION CRITERIA
* Need lo protea a downstream tteattncni system
* Enhanced reliabiUty
• Optimum use of the site
LIMTTATIONS
• Available space
DESIGN AND SIZING CONSIDERATIONS
• Refer to individual treattnent control BMPs
CONSTRUCnON/INSPECnON CONSIDERATIONS
Refer to individual tteatment control BMPs
MAINTENANCE REQUIREMENTS
* Refer to individual treattnent control BMPs
COST CONSIDERATIONS
Targeted Constituents
9 Sediment
O Nutrients
Q Heavy Metals
O Toxh Materials
9 Fhatable Materials
9 Oxygen Demand-
ing Substances
O Oil & Grease
9 Bacteria & Viruses
W Ukely to Have
Significant Impact
O Prot>able Low or Unkno¥m Impact
Implementation
Requirements
9 Capital Costs
# O&M Costs
% Maintenance
O Training
High O Low
TCS
Best^
Management
Practlces^
Industrial Handbook 5-69 March, 1993
APPENDIX 8
INDUSTRIAL / MUNICIPAL PROPRIETARY BMPS
i
CDS is the most effective system for the sustainable removal and
retention of suspended solids aind floatables from storm water.
REMOVES POLLUTANTS
The Continuous Deflective Separation (CDS) teclinology
utilizes a non-blocking, non-mectianical screening process
to remove pollutants from storm water flow and combined
sewer overflows (CSO). CDS units capture fine sands
and solids and are capable of removing more than 80%
of annual total suspended solids from storm water.
Additionally, CDS units remove 100% of floatables and
100% of all particles in the storm water which are equal
to or greater than one-half the size of the screen opening.
Studies show the units remove 93% of all particles which
are one-third the size of the screen opening, and 53% of
all particles one-fifth the size of the screen opening.
A conventional oil baffle within a CDS unit effectively
xjontrols oil and grease in storm water. With the addition
of sorbents, the permanent capture efficiency of oil and
grease is increased to 80-90%. The combination of a
conventional oil baffle and particulate sorbents is a unique
feature of a CDS storm water treatment unit. Once
pollutants are captured in a CDS unit, they cannot escape.
PROVEN TECHNOLOGY
The CDS technology has been proven by extensive
independent laboratory studies and hundreds of actual
installations in the United States and Australia. Copies of
these performance reports are available at our web site,
or by contacting our offices.
The CDS technology has achieved approval as a Best
Management Practice (BMP) by municipalities and state
DOTS throughout the United States. The USEPA lists CDS
as a structural BMP.
Standard CDS Unit Capacities and Physical Features
Manufacture
Malerial
Model
Designation
Approximate impervious CatclimenI Area (Acres)
Treatment Capacity
Q water quality
Screen
Diameter/Heiglit
(It)
Sump
Capaciiy
(yd3)
Deplh Below
Pipe Invert
(ft)
Foot Print
Diameter
(It)
Manufacture
Malerial
Model
Designation
Approximate impervious CatclimenI Area (Acres) cts MGD
Screen
Diameter/Heiglit
(It)
Sump
Capaciiy
(yd3)
Deplh Below
Pipe Invert
(ft)
Foot Print
Diameter
(It)
PrecasI Concrele
PIV1SU20J5 1-4 0.7 0.5 2.0/1.5 1.1 5.1 6.0
PrecasI Concrele
PMSU 20_20 2-6 1.1 0.7 2.0/2.0 1.1 5.7 6.0
PrecasI Concrele
PMSU 20_25 3-9 1.6 1.0 2.0/2.5 1.1 6.2 6.0
PrecasI Concrele
PSW & PMSU 30_28 6-17 3.0 1.9 3.0/2.8 1.4-2.1 6.9 6.0-6.5
PrecasI Concrele
PSWC & PMSU 40_40 12-33 6.0 3.9 4.0/4.0 1.9 9.7 8.3 PrecasI Concrele PSWC 56_40 & 50_40 & 50_50 18-61 9 & 11 5.8 & 7.1 5.6 / 4.0 & 5.0/5.0 1.9 9.7 9.5 PrecasI Concrele
PSWC 56_53 28-78 14 9 5.6/5.3 1.9 10.8 9.5
PrecasI Concrele
PSWC 56_68 38-106 19 12 5.6/6.8 1.9 12.5 9.5
PrecasI Concrele
PSWC 56_78 & PSW 70_70 50-144 25&26 16& 17 5.6 / 7.8 & 7.0/7.0 1.9-3.9 13.5 9.5
PrecasI Concrele
PSW 100_60 60-167 30 19 10.0/6.0 6.9-14.1 12.0 17.5
PrecasI Concrele
PSW100_80 100-278 50 32 10.0/8.0 6.9-14.1 14.0 17.5
PrecasI Concrele
PSW 10OJ 00 128-356 64 41 10.0/10.0 6.9-14.1 16.0 17.5
Fiberglass Premanufactured fiberglass units are available to treat small flows of 1 to 3 cfs
Cast-ln-Place Concrete CDS cast-in-place reinforced concrete units can be designed to treat flows up to 300 cfs
1) Raw storm water enters the
CDS unit's diversion chamber.
(2) A diversion weir guides the
flow into the unit's separation
chamber where a vortex is
formed.
(3) The vortex spins all floatables
and most suspended solids to
the center of the separation
chamber.
)The separation screen will not
become blocked due to the
washing vortex, but it will allow
liquid to move through.
(^The screened liquid which
passes through the process
quickly moves toward the
outlet.
(lO)The diversion weir is designed
to bypass excessive flows
without affecting the proper
operation of the CDS unit or
storm drain system. Bypass
flows will not wash out any of
the captured pollutants.
V^The cleaned water then moyes
• freely to the receiving water.
(J)The cleaned storm water moves out
of the separation chamber and into
the diversion chamber downstream
from the diversion weir.
(l)jhe sump can be equipped with an optional
basket to facilitate emptying the unit, or simply
clean with a vactor or clam bucket.
(^Suspended solids gently settle into
a sump where they remain until they
are removed.
MAINTENANCE
CDS units are self-operating. They have no moving parts
and they are entirely gravity driven, requiring only the
hydraulic energy available within the storm water flow.
The screens and supporting hardware are stainless steel
and will resist corrosion.
CDS units have very large sump capacities relative
to their design flows, and only need to be cleaned out
with a standard vactor truck approximately one to four
times per year. This operation eliminates workers' exposure
to the materials captured in the units.
KEY FEATURES and BENEFITS
Uses
• Storm Waler Treatment
• Combined Sewer Overflow Treatment
• Dry Weather Flow Diversion
Applications
• Capture and retention of suspended solids
sand, floatables. oil and grease, and other
gross pollutants from:
• Commercial Service and Parking Areas
• Industrial Areas
• Public Property and Parkland
• Residential Streets and Private Property
• Pretreatment for:
• Wetlands. Ponds, and Swales
• Media and Sand Filters
• Oil/Water Separators
Efficient
• Highly effective (up to 90%) in capturing
and retaining sediment as small as one-
third the screen aperture.
• Captures and retains 100% of floatables
and all other material greater than the
screen aperture.
Cost-Effective
• CDS provides the lowest cost per CFS
(Cubic Feet per Second) processed when
compared to other structural BMPs.
Large Flow Range
• From 0.7 to 300 CFS.
Non-Blocking and Non-Mechanical
• Standard CDS units have no moving part.s
They require no pov/er or supporting
infrastructure, anri ihey will not clog
Unobtrusive and Easy to Install
• CDS units are compact anri are installed
below ground, so space requirements are
modest. They are ideal for new construi;
tion as well as retrofit or redevelopment
Low-Cost. Safe and Easy Pollutant Removal
• Maintenance is easy using standard vactc
clam, or basket equipment which mini-
mizes maintenance personnel exposure
to hazardous material.
Improves Discharge Water Quality
• Removes floatables and suspended solids
from storm water runoff.
• Removes free oil and grease with the use
of an oil baffle, and/or sorbents.