URBAN BMP COST AND EFFECTIVENESS
SUMMARY DATA
FOR 6217(g) GUIDANCE
ROADS, HIGHWAYS, AND BRIDGES
January 29, 1993
WOODWARD-CLYDE
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URBAN BMP COST AND EFFECTIVENESS
SUMMARY DATA
FOR 6217(g) GUIDANCE
ROADS, HIGHWAYS, AND BRIDGES
January 29, 1993
WOODWARD-CLYDE ^
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ACKNOWLEDGEMENTS
The authors of this report were Ms. Lynn Mayo, Mr. Dale Lehman, Mr. Lawrence Olinger, and
Mr. Brian Donovan, Dr. Peter Mangarella, Ms. Teressa Hua, and Mr. Eric Strecker of
Woodward-Clyde.
The authors would like to thank Mr. Edward Drabkowski, Mr. Rod Frederick, Mr. Robert Goo
of the United States Environmental Protection Agency (EPA); Mr. Thomas Schueler of
Metropolitan Washington Council of Governments; and H.A. Jongedyk of the Federal Highway
Administration for their guidance and comments during the development of this document.
The project was funded by the EPA Assessment and Watershed Protection Division.
ii
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TABLE OF CONTENTS
Section Page
1.0 INTRODUCTION 1-1
2.0 POLLUTANTS FROM ROAD, HIGHWAYS, AND BRIDGES 2-1
3.0 MANAGEMENT PRACTICES - PLANNING AND DESIGN 3-1
3.1 LOCATE PROJECT AWAY FROM CRITICAL AREAS 3-1
3.2 DESIGN ROADWAYS TO FIT TERRAIN 3-1
3.3 REDUCE USE OF CURB 3-1
3.4 OBTAIN WIDER RIGHTS-OF-WAY 3-2
3.5 REDUCE USE OF SCUPPER DRAINS 3-2
3.6 PROTECT BRIDGES FROM SOUR 3-2
4.0 MANAGEMENT PRACTICES - EROSION AND SEDIMENT
CONTROL DURING CONSTRUCTION 4-1
5.0 MANAGEMENT PRACTICES - STORMWATER RUNOFF TREATMENT ... 5-1
5.1 DESCRIPTION 5-2
5.1.1 Highways and Roads 5-3
5.1.2 Roads Only 5-11
5.2 SUMMARY OF ADVANTAGES, DISADVANTAGES,
EFFECTIVENESS AND COST 5-18
5.3 EFFECTIVENESS 5-32
5.3.1 Highways and Roads 5-32
5.3.2 Roads Only . 5-39
5.4 COST 5-41
5.4.1 Highways and Roads 5-42
5.4.2 Roads Only 5-44
6.0 MANAGEMENT PRACTICES - OPERATION AND MAINTENANCE 6-1
6.1 DESCRIPTION 6-2
6.1.1 Maintenance of Vegetation 6-2
6.1.2 Street Cleaning 6-3
6.1.3 Deicing Chemical Use Management 6-3
6.1.4 Containment During Bridge Maintenance 6-5
6.2 SUMMARY TABLES 6-5
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TABLE OF CONTENTS (continued)
Section Page
6.3 EFFECTIVENESS 6-11
6.3.1 Maintenance of Vegetation 6-11
6.3.2 Street Cleaning 6-11
6.3.3 Deicing Chemical Use Management 6-12
6.3.4 Containment During Bridge Maintenance 6-13
6.4 COST 6-13
6.4.1 Maintenance of Vegetation 6-14
6.4.2 Street Cleaning 6-14
6.4.3 Deicing Chemical Use Management 6-15
6.4.4 Containment During Bridge Maintenance 6-15
7.0 MANAGEMENT PRACTICES OPTIONS 7-1
7.1 PLANNING AND DESIGN PRACTICES FOR ROADS
AND HIGHWAYS 7-1
7.2 PLANNING AND DESIGN PRACTICES FOR BRIDGES 7-3
7.3 CONSTRUCTION PROJECT PRACTICES 7-5
7.4 CONSTRUCTION SITE CHEMICAL CONTROL PRACTICES 7-6
7.5 OPERATION AND MAINTENANCE PREVENTIVE PRACTICES .... 7-7
7.6 OPERATION AND MAINTENANCE VEGETATIVE PRACTICES .... 7-9
7.7 RETROFIT PRACTICES 7-10
8.0 REFERENCES 8-1
APPENDICES
A. EFFICIENCY DATA
B. COST DATA
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TABLE OF CONTENTS (continued)
LIST OF TABLES
TABLE 2-1.
TABLE 2-2.
TABLE 2-3.
TABLE 2-4.
HIGHWAY RUNOFF CONSTITUENTS AND THEIR
PRIMARY SOURCES 2-2
SITE MEDIAN CONCENTRATIONS IN HIGHWAY RUNOFF . 2-3
CONCENTRATIONS FOR TOXIC EFFECTS 2-4
POTENTIAL ENVIRONMENTAL IMPACTS OF ROAD SALT . 2-7
TABLE 5-1.
TABLE 5-2.
TABLE 5-3.
TABLE 6-1.
TABLE 6-2.
TABLE 6-3.
ADVANTAGES AND DISADVANTAGES OF MANAGEMENT
PRACTICES 5-20
EFFECTIVENESS OF MANAGEMENT PRACTICES FOR
CONTROL OF RUNOFF FROM NEWLY DEVELOPED
AREAS 5-24
COST OF MANAGEMENT PRACTICES FOR CONTROL
OF RUNOFF FROM NEWLY DEVELOPED AREAS 5-29
DEICING MATERIALS 6-6
OPERATION AND MAINTENANCE MANAGEMENT PRACTICES
EFFECTIVENESS AND COST SUMMARY 6-7
OPERATION AND MAINTENANCE MANAGEMENT PRACTICES
EFFECTIVENESS AND COST SUMMARY 6-10
LIST OF FIGURES
FIGURE 2-1.
TOTAL HARDNESS LEVELS OF SURFACE WATERS IN THE
CONTINENTAL UNITED STATES 2-6
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1.0
INTRODUCTION
In November 1990, the U.S. Congress reauthorized the Coastal Zone Act Reauthorization and
Amendments (CZARA). As part of this reauthorization, Congress created a new, distinct
program to address nonpoint source (NPS) pollution of coastal waters (Section 6217). The U.S.
Environmental Protection Agency (EPA) and National Oceanic and Atmospheric Administration
(NOAA) jointly drafted Proposed Program Guidance for Section 6217 of CZARA. EPA has
lead responsibility for developing the Management Measures Guidance required under Section
6217(g).
EPA established five Federal/State Work Groups to assist in preparation of the 6217(g)
Guidance. Woodward-Clyde has supported the Urban Work Group through the collection and
analysis of information on Best Management Practices (BMPs) used to control urban NPS
pollution. The results of these efforts includes four books that present cost and effectiveness
information on BMPs for:
• Erosion and Sediment Control;
• Post Construction Runoff;
• Onsite Sewage Disposal Systems; and
• Roads, Highways and Bridges.
This report is a summary of the cost and pollutant removal effectiveness information that was
obtained from published literature regarding management practices for roads, highways and
bridges. The report also contains information regarding the pollutants found in the runoff from
highways and appropriate management practices and systems of management practices for the
control of (NPS) pollution.
This document contains information from over 40 documents. Over 200 documents were
reviewed regarding roads, highways and bridges management practices. The documents were
obtained through literature searches and telephone contacts with all states and territories with
approved Coastal Zone Management Plans. Cost and effectiveness data from the various
management practices presented in the documents were reviewed and analyzed to develop
summary information. Data were omitted from consideration where substandard field technique
was used in the collection of the data or if results were influenced by atypical climatological or
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site characteristics (e.g. unusually heavy rainfall or prolonged drought). Also, only management
practices that have been applied in the field were considered. Experimental practices only
applied in a research setting were not considered. It should be noted that the documents
obtained and reviewed do not include all of the published literature regarding roads, highways
and bridges management practices. However, many of the documents obtained were summaries
of many other investigations.
Section 2.0 contains descriptions of the pollutants found in runoff from highways. Sections 3.0
through 6.0 describe the management practices available for the control of nonpoint source
pollution from roads, highways and bridges. These practices have been divided into four
categories: planning and design (Section 3.0), erosion and sediment control during construction
(Section 4.0), storm water runoff treatment (Section 5.0),and operation and maintenance (Section
6.0). Section 7.0 describes some management practice options. Roads, highways and streets
are referred to throughout this section. The following defines what is meant by a road, highway
or street in this guidance document.
Roads
Roads are defined as public ways for purposes of vehicular travel and access to adjacent
property. Roads are usually designed without curb and gutter and with grassed swales to handle
drainage. Roads are generally located in rural areas and can be paved or unpaved.
Streets
Streets are dedicated public rights-of-way for access to abutting residential and other urban
properties. Streets are usually designed with curbs and gutters and drainage inlets. Streets are
generally located in urban areas, rural and suburban subdivisions and are mostly paved. The
terms for "streets" and "roads" are often used interchangeably.
Highways
A general term denoting a public right-of-way for purposes of vehicular travel. Highway
systems include the National Highway System and the Interstate System.
The Appendix presents the data analyzed to develop summary cost and effectiveness information.
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2.0
POLLUTANTS FROM ROADS, HIGHWAYS, AND BRIDGES
Automobiles generate pollutants that are deposited on street surfaces through wear and corrosion
of parts, leaking oils and lubricants, and combustion by-products. A wide range of pollutants
are generated, but the main pollutants of concern are metals and hydrocarbons, which are often
found at high concentrations on street surfaces. (British Columbia Research Corp., 1991) Table
2-1 lists the pollutants commonly found in stormwater runoff from roads, highways and bridges
and their sources. The disposition and subsequent magnitude of pollutants found in highway
runoff are site-specific and affected by traffic volume, road or highway design, surrounding land
use, climate, and accidental spills.
As summarized in Pollutant Loadings and Impacts from Highway Stormwater Runoff (Driscoll
et al., 1990), the Federal Highway Administration (FHWA) has conducted an extensive field
monitoring and laboratory analysis program to determine the pollutant concentrations in highway
runoff. Data from 993 highway runoff events at 31 sites in 11 states were analyzed and the
results are shown in Table 2-2. The concentration is given as an event mean concentration
(EMC). This is the median of all the average concentrations of a pollutant in the total runoff
volume produced by an individual storm event.
The pollutant concentrations were found to fall into two distinct groups depending on whether
the highway was located in an urban or a rural setting. An urban highway is defined as a road
with average daily traffic more than 30,000 vehicles. A rural highway is defined as a road with
average daily traffic less than 30,000 vehicles.
The research indicated that for highways discharging to lakes, the pollutants of major concern
are phosphorus and heavy metals. For highways discharging to streams, the pollutants of major
concern are heavy metals - copper, lead and zinc.
EPA has developed pollutant criteria for protecting freshwater aquatic life (see Table 2-3). The
Acute Criteria area based on the result of 96-hour test exposures using the continuous exposure
concept. The Threshold Effect Level is the concentration that causes mortality of the most
sensitive individual of the most sensitive species. This addresses the phenomena that stormwater
runoff typically produces short-duration intermittent exposure to pollutants.
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TABLE 2-1. HIGHWAY RUNOFF CONSTITUENTS AND THEIR PRIMARY
SOURCES
POLLUTANTS
PRIMARY SOURCES
Particulates
Pavement wear, vehicles, atmosphere, maintenance
Nitrogen, Phosphorus
Atmosphere, roadside fertilizer application
Lead
Leaded gasoline (auto exhaust), tire wear (lead oxide filler material),
lubricating oil and grease, bearing wear
Zinc
Tire wear (filler material), motor oil (stabilizing additive), grease
Iron
Auto body rust, steel highway structures (guard rails, etc.), moving engine
parts
Copper
Metal plating, bearing and bushing wear, moving engine parts, brake lining
wear, fungicides and insecticides
Cadmium
Tire wear (filler material), insecticide application
Chromium
Metal plating, moving engine parts, break lining wear
Nickel
Diesel fuel and gasoline (exhaust), lubricating oil, metal plating, bushing
wear, brake lining wear, asphalt paving
Manganese
Moving engine parts
Cyanide
Anticake compound (ferric ferrocyanide, sodium ferrocyanide, yellow
prussiate of soda) used to keep deicing salt granular
Sodium, Calcium, Chloride
Deicing salts
Sulphate
Roadway beds, fuel, deicing salts
Petroleum
Spills, leaks or blow-by of motor lubricants, antifreeze and hydraulic fluids,
asphalt surface Ieachate
PCB
Spraying of highway rights-of-way, background atmospheric deposition, PCB
catalyst in synthetic tires
Source: U.S. DOT, FHWA, Report No. FHWA/RD-84/07-060, June 1987.
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TABLE 2-2. SITE MEDIAN CONCENTRATIONS IN HIGHWAY RUNOFF
A. URBAN HIGHWAYS - AVERAGE DAILY TRAFFIC USUALLY MORE THAN 30,000 VEHICLES PER
DAY
SITE MEDIAN EMC CONCENTRATION IN mg/1
PERCENT OF SITES HAVING A MEDIAN EMC LESS THAN INDICATED
CONCENTRATION
POLLUTANT
10% OF SITES
50% MEDIAN SITE
90% OF SITES
TSS
68
142
295
VSS
20
39
78
TOC
8
25
74
COD
57
114
227
N02+3
0.39
0.76
1.48
TKN
1.06
1.83
3.17
P04-P
0.15
0.40
1.06
COPPER
0.025
0.054
0.119
LEAD
0.102
0.400
1.562
ZINC
0.192
0.329
0.564
B. RURAL HIGHWAYS - AVERAGE DAILY TRAFFIC USUALLY LESS THAN 30,000 VEHICLES PER
DAY
TSS
12
41
135
VSS
6
12
25
TOC
4
8
17
COD
28
49
85
N02+3
0.23
0.46
0.91
TKN
0.34
0.87
2.19
P04-P
0.06
0.16
0.48
COPPER
0.010
0.022
0.050
LEAD
0.024
0.080
0.272
ZINC
0.035
0.080
0.185
Source: Driscoll et al., 1990
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TABLE 2-3. CONCENTRATIONS FOR TOXIC EFFECTS
SURFACE WATER
TOTAL
HARDNESS (PPM)
EPA ACUTE CRITERIA
(mg/I)
EPA NURP SUGGESTED THRESHOLD EFFECT
LEVEL (mg/1)
COPPER
LEAD
ZINC
COPPER
LEAD
ZINC
50
0.009
0.034
0.181
0.020
0.150
0.380
60
0.011
0.043
0.210
0.025
0.200
0.440
80
0.014
0.061
0.267
0.030
0.250
0.560
100
0.018
0.082
0.321
0.040
0.350
0.675
120
0.021
0.103
0.374
0.045
0.450
0.785
140
0.024
0.125
0.425
0.055
0.550
0.890
160
0.028
0.149
0.475
0.065
0.650
1.000
180
0.031
0.173
0.523
0.070
0.750
1.100
200
0.034
0.197
0.571
0.080
0.850
1.200
220
0.037
0.223
0.618
0.090
0.950
1.300
240
0.040
0.249
0.664
0.095
1.050
1.400
260
0.044
0.276
0.710
0.100
1.200
1.500
280
0.047
0.303
0.755
0.110
1.300
1.600
300
0.050
0.331
0.800
0.115
1.400
1.700
NOTE: THRESHOLD EFFECT LEVEL - The concentration that causes mortality of the most sensitive individual of the most sensitive
species
Source: Driscoll et al., 1990
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EPA has developed pollutant criteria for protecting freshwater aquatic life (see Table 2-3). The
Acute Criteria are based on the result of 96-hour test exposures using the continuous exposure
concept. The Threshold Effect Level is the concentration that causes mortality of the most
sensitive individual of the most sensitive species. This addresses the phenomena that stormwater
runoff typically produces short-duration intermittent exposure to pollutants. The criteria varies
with the hardness of the water, which varies regionally as shown in Figure 2-1. For additional
information on Acute Criteria and Threshold Effect Level see Driscoll et al., 1990.
In coastal areas, which often have low hardness, the copper and lead concentrations from
highway runoff can exceed the Threshold Effect Level. Copper, lead and zinc concentrations
typically exceed the Acute Criteria.
In colder regions where deicing agents are used, deicing chemicals and abrasives are the largest
source of pollutants during winter months. Deicing salt (primarily sodium chloride, NaCl) is
the most commonly used deicing agent. Potential pollutants from deicing salt includes sodium,
chloride, ferric ferrocyanide (used to keep the salt in granular form), and sulphate. Table 2-4
summarizes potential environmental impacts caused by road salt. Other chemicals used as a salt
substitute include calcium magnesium acetate (CMA), and less frequently, urea and glycol
compounds. Researchers have differing opinions on the environmental impacts of CMA
compared to road salt (Salt Institute, undated) (Chevron Chemical Company, 1991) and
(Transportation Research Board, 1991).
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Jd oo
o $
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a.
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i
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£
a
•o
0
1
I
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3.
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Hardness as C3CO3 (ppm)
120-180
I I Under 60 1 180-240
\:Y:\ 60-120 ES Over 240
Source: Water alias of the United States, 1973
Water Information Cenler, Porl Washington, New YorV
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TABLE 2-4. POTENTIAL ENVIRONMENTAL IMPACTS OF ROAD SALT
Environmental Resource
Potential Environmental Impact of Road Salt (NaCl)
Soils
May accumulate in soil. Breaks down soil structure,
increases erosion. Causes soil compaction that results in
decreased permeability.
Vegetation
Osmotic stress and soil compaction harm root systems.
Spray causes foliage dehydration damage. Many plant
species are salt sensitive.
Groundwater
Mobile Na and CI ions readily reach groundwater.
Increases Na and CI concentrations in well water as well as
alkalinity and hardness.
Surface Water
Causes density stratification in ponds and lakes that can
prevent reoxygenation. Increases runoff of heavy metals
and nutrients through increased erosion.
Aquatic Life
Monovalent Na and CI ions stress osmotic balances. Toxic
levels: Na - 500ppm for stickleback; and CI - 400 ppm for
trout.
Human/Mammalian
Sodium is linked to heart disease and hypertension.
Chlorine causes unpleasant taste in drinking water. Mild
skin and eye irritant. Acute oral LD50 in rats is
approximately 3000mg/kg (slightly toxic).
Source: Chevron, 1991
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3.0
MANAGEMENT PRACTICES - PLANNING AND DESIGN
With proper planning and design the pollutant loads generated from roads, highways, and
bridges can be minimized. Proper planning and design are often the most cost effective
management practices because they reduce the requirements and costs for stormwater runoff
treatment and operation and maintenance management practices. The Federal Highway
Administration (FHWA) has developed a computer model that can be used in the planning
process to examine the impacts of road projects. The following is a discussion of planning and
design management practices available.
3.1 LOCATE PROJECT AWAY FROM CRITICAL AREAS
A road's impact on nonpoint source pollution should be considered early in the planning process.
Early identification of sensitive land or water areas, and incorporating information about these
areas in planning, can often prevent disturbance of these areas. Every possible means should
be used to avoid disturbing wooded areas, wetlands, floodplains, ponds, rivers and streams
(AASHTO, 1991). In addition, buffers should be provided between a highway and water body
to protect the waterbody.
3.2 DESIGN ROADWAYS TO FIT TERRAIN
A roadway should be designed to minimize the amount of disturbance. A roadway should be
constructed as close to existing grade as possible to minimize the area that must be cut or filled.
However, when cut or fill is required, the slope must be designed to keep stormwater runoff
velocities below erosive levels. AASHTO has location and design guidelines available for state
highway agency use that describe the considerations necessary to control highway-related
pollutants (AASHTO, 1991).
3.3 REDUCE USE OF CURB
Where practical, vegetative systems should be used instead of curbs. Curb systems capture and
accumulate pollutants between storms, as well as concentrate runoff. This increases the pollutant
load in the stormwater runoff. Without a curb system, the pollutants are blown to the shoulder
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and right-of-way which reduces the pollutant load available to the runoff.
A vegetative system such as grassed swales or vegetative buffer strips reduce pollutant loads as
will be discussed in Section 5.0.
3.4 OBTAIN WIDER RIGHTS-OF-WAY
Where possible, rights-of-way widths sufficient to implement the structural management practices
should be obtained.
3.5 REDUCE USE OF SCUPPER DRAINS
Scupper drains are used on bridges to collect stormwater runoff which is then discharged directly
below the bridge. The use of scupper drains should be minimized. Where possible the bridge's
stormwater runoff should be collected, piped and treated in a treatment facility located on the
adjacent land.
3.6 PROTECT BRIDGES FROM SCOUR
If scour is likely to occur, the bridge piers and abutments should be designed to provide
protection against scour damage. Embankment slopes that are adjacent to structures subject to
erosion, should be adequately protected by flexible mattresses, rip-rap, spur dikes or other
appropriate construction.
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4.0
MANAGEMENT PRACTICES - EROSION AND SEDIMENT
CONTROL DURING CONSTRUCTION
Erosion and sediment controls should be used during the construction of roads, highways and
bridges. The controls are needed because soil eroded from construction sites may contaminate
lakes, streams, and reservoirs, restrict drainage ways, plug culverts, damage adjacent properties,
and affect the ecosystems of streams (AASHTO, 1990). According to Section 650B of the
Federal-Aid Policy Guide, all Federal-aid highways and highways constructed under the direct
supervision of the Federal Highway Administration must be constructed and operated so that
erosion and sediment damage to the highway and adjacent properties is minimized.
Erosion and sedimentation from construction of roads, highways, and bridges, and from
unstabilized cut-and-fill areas, can significantly impact receiving waters and wetlands with silt
and other pollutants including heavy metals, hydrocarbons, and toxic substances. Erosion and
sediment control plans are effective in describing procedures for mitigating erosion problems at
construction sites before any land disturbing activity begins.
Bridge construction projects include grade separations (bridges over roads) and waterbody
crossings. Erosion problems at grade separations result from water running off the bridge deck
and runoff waters flowing onto the bridge deck during construction. Controlling this runoff can
prevent erosion of slope fills and the undermining failure of the concrete slab at the bridge
approach. Bridge construction over waterbodies requires careful planning to limit the
disturbance of streambanks. Soil materials excavated for footings in or near the water should
be removed and relocated to prevent the material from being washed back into the waterbody.
Protective berms, diversion ditches, and silt fences parallel to the waterway can be effective in
preventing sediment from reaching the waterbody.
Detailed information on erosion and sediment control management practices, their effectiveness
and cost, and recommended management practices can be found in Urban BMP Cost and
Effectiveness Summary Data for 6217fp> Guidance - Erosion and Sediment Control During
Construction (Woodward-Clyde, 1993). The following is a list of the various erosion and
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sediment control management practices:
• Schedule projects so clearing and grading is done during time of minimum
erosion potential
• Stage construction
• Only clear areas essential for construction
• Avoid disturbing vegetation on steep slopes or other critical areas
• Route traffic to avoid existing or newly planned vegetation construction
• Protect natural vegetation with fencing, tree armoring, and retaining walls or tree
wells
• Seed and fertilize
• Seed and mulch
• Mulching
• Sodding
• Where practical stockpile topsoil and reapply to revegetate site
• Cover or stabilize topsoil stockpiles
• Wind erosion controls
• Intercept runoff above disturbed slopes and convey it to a permanent channel or
storm drain
• On long or steep disturbed or man-made slopes, construct benches, terraces, or
ditches at regular intervals to intercept runoff
• Provide linings for channels
• Check dams
• Sediment basins
• Sediment traps
• Filter fabric fences
• Straw bale barriers
• Inlet protection
• Construction entrances
• Vegetative filter strips
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5.0
MANAGEMENT PRACTICES - STORMWATER RUNOFF TREATMENT
The Federal Highway Administration (FHWA) has completed a four phase research program to
identify and quantify the effects of highway runoff and develop management measures to protect
receiving waters. The research resulted in a list of cost-effective structural management
practices for use on highway projects (Hartigan et al, 1989):
• Vegetative controls (includes vegetative filter strips and grassed swales)
• Wet detention ponds
• Extended detention dry ponds
• Infiltration basins
• Wetlands.
These practices, along with extended detention wet ponds can also be effective for controlling
runoff from non-highway roads.
This section will describe these management practices and the cost and effectiveness of the
systems. In addition, the Federal Highway Administration developed an interactive computer
model which can be used on specific sites to model the effectiveness of vegetative filter strips
(overland flow), grassed swales, detention or wet ponds, and infiltration devices (Dorman et al,
1989).
The FHWA research also identified some ineffective measures for highway projects (Hartigan
Catch basins
Porous pavement
Street cleaning
Filtration devices for sediment control.
et al, 1989):
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Although catch basins and porous pavement are not effective for highways, they may be effective
for some roadways and parking lots and are discussed in this section. Street cleaning is also not
effective for highways. However, other research has indicated that street cleaning may be
effective under certain circumstances in urban areas. This research will be discussed in Section
6.0 of this report (Operation and Maintenance).
Filtration devices for sediment control includes straw bales, filter fabric fence, and gravel filters.
These practices are generally effective for filtering out large sized particles but are ineffective
for trapping finer solids. This makes these devices generally effective for sediment control
during construction but not for control of post-construction highway runoff. The use of these
devices are discussed in a separate report - Urban BMP Cost and Effectiveness Summary Data
for 6217(g) Guidance - Erosion and Sediment Control During Construction (Woodward-Clyde,
1993).
Section 5.1 describes the management practices available. Section 5.2 summarizes the
advantages and disadvantages, effectiveness, and cost of the practices. Section 5.3 further
discusses the practices' effectiveness and the basis for determining effectiveness and Section 5.4
further discusses the practices' cost and the basis for determining cost.
5.1 DESCRIPTION
The Stormwater Runoff Treatment Management Practices have been divided into two categories.
Those typically effective for highways and roads and those typically not effective for highways
but are effective for other roadways. The following is a description of various road and highway
stormwater runoff structural management practices. In addition to providing pollutant removal,
several practices can also control the post-development peak flow rate which is important for
protecting downstream channels from erosion due to increased velocities and runoff volumes.
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5.1.1 Highways and Roads
Vegetative Filter Strips
Vegetative filter strips are similar to grass swales, except they are only effective for overland
sheet flow. Runoff must be evenly distributed across the filter strip. If the water concentrates
and forms a channel, the filter strip will not perform properly. Level spreading devices are
often used to distribute the runoff evenly across the strip. Vegetated filter strips do not
effectively treat high-velocity flows and therefore are generally recommended for use in
agriculture and low density development and other situations where runoff does not tend to be
concentrated. Also, vegetative filter strips are often used as pretreatment for other structural
practices, such as infiltration basins and infiltration trenches.
Vegetative filter strips and grassed swales are the most commonly used management practices
along highways. These practices are often used because they are adaptable to many site
conditions, are flexible in design and layout and are relatively inexpensive. Vegetative filter
strips may be used alone or they may be used as pretreatment to other management practices
such as infiltration basins or ponds (Dorman et al, 1989).
Vegetative filter strips should have relatively low slopes, adequate length, and be planted with
erosion resistant plant species. Vegetative filter strips which treat runoff from roads in areas
with freezing winters must contain salt tolerant vegetation. The main factors that influence the
removal efficiency are the vegetation, soil infiltration rate, and flow depth and travel time.
These are dependent on the contributing drainage area, slope of strip, vegetative cover type and
strip length.
Operation and Maintenance
Maintenance requirements for vegetative filter strips are low. The strips should be inspected
frequently the first few months and years after construction to make sure a dense, vigorous
vegetation is established and the flow does not concentrate.
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If natural vegetative succession is allowed to proceed, little other maintenance is required.
Natural succession is the transformation of grass to meadow to second growth forest and it
typically enhances pollutant removal. Short strips are typically maintained as lawns and must
be mowed 2-3 times a year to suppress weeds and to interrupt natural succession. Excessive use
of pesticides, fertilizers, and other chemicals should be avoided. Accumulated sediment must
also be periodically removed near the top of the strip (Schueler, 1987).
Grassed Swales
Grassed swales are low gradient conveyance vegetated channels that are used in place of buried
storm drains or curb-and-gutters. The swales should have relatively low slope, adequate length,
and be planted with erosion resistant vegetation to effectively remove pollutants.
Grassed swales and vegetative filter strips are the most commonly used management practices
along highways. These practices are often used because they are adaptable to many site
conditions, are flexible in design and layout and are relatively inexpensive. Grassed swales may
be used alone or as pretreatment to other management practices such as infiltration basins or
ponds (Dorman et al, 1989).
The main factors that influence the removal efficiency are the vegetation, soil infiltration rate,
flow depth, depth to water table and flow travel time. These are dependent on the contributing
drainage area, slope, vegetative cover type and length.
Because swales do not have high pollutant removal rates they are typically used as part of a
storm water management/ management practice system. Swales can replace curb and gutter and
storm sewer systems in low-density residential and recreational areas. Swales have an advantage
over curb and gutter and pipes because they can provide pollutant removal, reduce peak flows
and have a lower construction cost. However, swales often lead into storm drain inlets to
prevent the concentrated flows from gullying and eroding the swale during large storms
(Schueler, 1987).
Roadside swales are usually not practical in high density urban areas because each driveway and
road intersection must have a culvert. Swales are also not practical on very flat grades, steep
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slopes, or in wet or poorly drained soils (SWRPC, 1991). Grassed swales that treat runoff from
roads in areas with freezing winters must contain salt tolerant vegetation.
Operation and Maintenance
Maintenance requirements are basically the same as normal lawn activities such as mowing,
watering, spot reseeding and weed control. However, maintenance can also cause problems such
as mowing too close to the ground or excessive application of fertilizers.
The swale should be mowed at least twice each year to stimulate vegetative growth, control
weeds, and maintain the capacity of the system. The grass should never be mowed shorter than
3 to 4 inches (Bassler, Undated).
Wet Ponds
Wet ponds are basins designed to maintain a permanent pool of water and temporarily store
stormwater runoff until it is released from the structure at flow rates less than pre-development
rates. Unlike extended detention wet ponds the stormwater is not stored for an extended period
of time. Enhanced designs include a forebay to trap incoming sediment where it can easily be
removed. A fringe wetland can also be established around the perimeter of the pond.
Wet ponds are not typically used for drainage areas less than 10 acres (Schueler, 1987). Pond
liners are required if the native soils are permeable (SCS soil group A and B) or if there is
fractured bedrock. If the bedrock layer is close to the surface, high excavation costs may make
the wet pond impractical. Wet ponds are not typically used in heavily urbanized areas because
of space constraints.
The main factors that influence the removal efficiencies are permanent pool volume and pond
shape (including inlet and outlet configuration) and degree of maintenance provided.
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Operation and Maintenance
Wet ponds require similar routine maintenance as extended detention dry ponds. These ponds
can be expected to lose approximately 1% of their runoff storage capacity per year due to
sediment accumulation. The sediments accumulate out of sight, under the permanent pool.
Therefore, wet ponds require less frequent sediment removal when compared to extended
detention dry ponds. The recommended sediment clean out cycle is about every 10 to 20 years
(British Columbia Research Corp., 1991).
Under EPA regulations (40 CFR 261) the material that is cleaned out from a detention pond
must be analyzed to determine if it is a hazardous waste. Therefore, a toxicity test should be
done for accumulated sediments removed from ponds. If the sediment fails the test, it is subject
to the Recource Conservation and Recovery Act (RCRA) and must be disposed of at a RCRA
approved facility (Dorman et al, 1989). However, a study conducted in Florida found that the
bottom sediment sampled from nine ponds that received runoff water from highways all had
metal concentrations measured well below the regulatory level to be considered hazardous waste.
Therefore, the sediment can be used if some form if fill is needed such as noise barriers
(berms), highway slopes, or eroded areas. The study also predicted a required dredging cycle
between 7 and 47 years with an average of approximately 25 years (Yousef et al, 1991).
With proper maintenance wet ponds should have a long useful life. However, the concrete pipes
used for outlets often need to be replaced after 50 years.
Extended Detention Wet Ponds
Extended detention wet ponds temporarily detain a portion of the runoff after a storm and use
an outlet device to regulate outflow at a specified rate, which allows the solids time to settle out.
Extended detention wet ponds are designed to maintain a permanent pool of water and
temporarily store stormwater runoff for an extended period. The storm water runoff is typically
detained 12 to 72 hours. Enhanced designs include a forebay to trap incoming sediment where
it can be easily removed. A fringe wetland can be established around the perimeter of the pond.
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Extended detention wet ponds are not typically used for drainage areas less than 10 acres
(Schueler, 1987). Pond liners are required if the pond soils are permeable (SCS soil group A
and B) or if there is fractured bedrock. If the bedrock layer is close to the surface, high
excavation costs may make the extended detention wet pond not practical. Extended detention
wet ponds are typically not used in heavily urbanized areas because of space constraints.
Extended detention wet ponds are typically more effective than the wet ponds, due to the
increased settling time provided for the stormwater runoff. The main factors that influence the
removal efficiencies are permanent pool volume, pond shape, and detention time and degree of
maintenance provided.
Operation and Maintenance
Extended wet ponds require maintenance and have a useful life similar to those for wet ponds.
Extended Detention Dry Ponds
Extended detention dry ponds temporarily detain a portion of the runoff after a storm and uses
an outlet device to regulate outflow at a specified rate, which allows the solids time to settle out.
Extended detention dry ponds are typically comprised of two stages: an upper stage which
remains dry except for larger storms, and a lower stage that is designed for typical storms. The
pond's outlet structure is typically sized for water to be detained at least 12 hours, but fully
drain within 72 hours.
Extended detention dry ponds are not usually used for drainage areas less than 10 acres
(Schueler, 1987). If the bedrock layer is close to the surface, high excavation costs may make
the extended detention dry pond impractical. In addition, if the water table is within 2 feet of
the bottom of the pond, there may be problems with standing water.
Extended detention dry ponds typically cannot be used in already developed heavily urbanized
areas because of space constraints. However, they are a practical means of retrofitting dry
ponds to obtain water quality benefits.
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Operation and Maintenance
The main factors that influence the removal efficiencies are the storage volume, detention time,
basin shape and degree of maintenance provided.
Routine maintenance includes mowing, debris/litter removal, inlet and outlet maintenance and
inspection. In addition, nuisance control may be necessary for odors and mosquitos problems
that are caused by occasional standing water and soggy conditions within the lower stage of an
extended detention dry pond. Non-routine maintenance includes sediment removal. Extended
detention dry ponds are estimated to lose approximately 1 % of their runoff storage capacity per
year due to sediment accumulation. Sediment removal for extended detention dry pond is
therefore recommended every 5-10 years with more frequent spot removals around the outlet
control device (British Columbia Research Corp., 1991).
Under EPA regulations (40 CFR 261) the material that is cleaned out from a detention pond
must be analyzed to determine if it is a hazardous waste. Therefore, a toxicity test should be
done for accumulated sediments removed from ponds. If the sediment fails the test, it is subject
to the Recource Conservation and Recovery Act (RCRA) and must be disposed of at a RCRA
approved facility (Dorman et al, 1989). However, a study conducted in Florida found that the
bottom sediment sampled from nine ponds, which received runoff water from highways, all had
metal concentrations measured well below the regulatory level to be considered hazardous waste.
Therefore, the sediment can be used if some form if fill is needed such as noise barriers
(berms), highway slopes, or eroded areas. The study also predicted a required dredging cycle
between 7 and 47 years with an average of approximately 25 years (Yousef et al, 1991).
With proper maintenance, extended detention dry ponds can have a long useful life. However,
concrete pipes used for outlets often need to be replaced after 50 years.
Infiltration Basins
Infiltration basins are basins that temporarily store runoff while it percolates into the soil through
the basins' bottom and sides. Infiltration basins should drain within 72 hours and are therefore
generally dry. This is needed to maintain aerobic conditions in order to favor bacteria that aid
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in pollutant removal and to ensure that the basin is empty for the next storm (Schueler, 1987).
Infiltration basins must be designed to trap coarse sediment before it enters the basin proper and
clogs the surface soil pore on the basin floor. If there is concentrated flow, a sediment trap
could be used. If there is sheet flow, a vegetative filter strip could be used.
In-line infiltration basins are typically used for drainage areas from 5 to 50 acres (Schueler,
1987). There must be at least 4 feet of permeable soil (SCS soil group A or B) between the
bottom of the basin and bedrock or highwater table. Infiltration basins are not effective when
the soil is frozen.
The main factors that influence the removal efficiency are the storage volume, basin surface area
and soil percolation rates.
Any runoff that percolates into the ground and reaches surface waters through the groundwater
is commonly assumed to have had the pollutants removed by soil processes such as filtration and
biological action. Therefore, any runoff and pollutants that percolate into the ground are
assumed to be removed. The validity of this assumption depends on the pollutants of concern,
their chemical properties and local conditions.
Operation and Maintenance
Routine maintenance requirements include inspecting the basin after every major storm for the
first few months after construction and annually thereafter, mowing frequently enough to prevent
woody growth, removing litter and debris and revegetating eroded areas. Also, the accumulated
sediment should be removed periodically. The infiltration capacity of a soil will decrease over
time. If the decrease is due to surface clogging, the soil can be deeply tilled or excavated and
replaced. Maryland recommends deep tilling every 5 to 10 years (Schueler, 1987). A
nonfunctioning infiltration basin can also be converted into a wet pond.
According to an infiltration practice survey completed in Maryland, infiltration basins had a
higher failure rate than infiltration trenches or dry wells. Four to six years after construction,
only 38% of the basins (as opposed to 53% of the trenches) functioned as designed. The main
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problem with the basins were inappropriate ponding of water and excessive sediment and debris
(Lindsey, 1991).
Infiltration basins which are properly maintained should have a useful life of 25-50 years before
the outlet structure needs to be replaced. However, as indicated above the basins useful life may
be shortened due to clogging.
Infiltration basins are easier to maintain than infiltration trenches because infiltration trenches
are more susceptible to clogging from sediment, oil, and grease from highway runoff.
Therefore, infiltration basins are the preferred management practices for highways (Dorman et
al, 1989).
Constructed Stormwater Wetlands
Constructed stormwater wetlands are shallow pools that create growing conditions suitable for
the growth of marsh plants. These stormwater wetlands are designed to maximize pollutant
removal through wetland uptake, retention and settling. Constructed stormwater wetlands
typically are not located within delineated natural wetlands and should be located to have a
minimal impact on surrounding areas. In addition, constructed stormwater wetlands differ from
artificial wetlands created to comply with mitigation requirements in that they do not replicate
all the ecological functions of natural wetlands. (Schueler et al, 1992).
Stormwater wetlands usually fall into one of five basic designs: shallow marsh system,
pond/wetland system, extended detention wetland, pocket wetlands, and fringe wetlands.
The main factors that influence the removal efficiency are the size and volume of the wetland
system, flow patterns through the wetland area, the wetlands biota, time of year and degree of
maintenance.
Operation and Maintenance
Constructed stormwater wetlands have maintenance requirements similar to those for wet ponds.
In addition, wetland vegetation should be harvested annually to provide nutrient removal and
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prevent flushing of dead vegetation from the wetland during the die-down season (British
Columbia Research Corp., 1991). The useful life span is indefinite.
5.1.2 Roads Only
Infiltration Trenches and Dry Wells
Infiltration trenches and dry wells are shallow excavated holes or ditches that have been back-
filled with stone to form an underground reservoir. The two practices are similar except that
dry wells only control small volumes of runoff, such as the runoff from a rooftop. Infiltration
trenches can control several acres of drainage. Infiltration trenches will be discussed in this
section, but the information applies to both infiltration trenches and dry wells.
Runoff is temporarily stored in the trench as it percolates into the soil through the trench's
bottom and sides. Infiltration trenches should drain within 72 hours. This is needed to maintain
aerobic conditions in order to favor bacteria that aid in pollutant removal and to ensure that the
trench is empty for the next storm (Schueler, 1987). Infiltration trench systems must be
designed to trap coarse sediment before it enters the trench proper and clogs the soil pores. This
may be achieved by using a vegetative filter strip or appropriate upstream inlet design.
Infiltration trenches are typically used for drainage areas less than 5 to 10 acres and may not be
economically practical on larger sites. Trenches are sometimes the only economical practice for
these small sites (Schueler, 1987).
There must be at least 4 feet of permeable soil (SCS soil group A or B) between the bottom of
the trench and bedrock or highwater table.
The main factors that influence the removal efficiency are the storage volume, trench surface
area, and soil percolation rates.
Any runoff that percolates into the ground and reaches surface waters through the groundwater
is assumed to have had the pollutants removed by soil processes such as filtration and biological
action. Therefore, any runoff and pollutants that percolate into the ground are assumed to be
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removed. The validity of this assumption depends on the pollutants of concern, their chemical
properties and local conditions.
Operation and Maintenance
Routine maintenance requirements include inspecting the basin after every major storm for the
first few months after construction and annually thereafter, mowing the filter strips frequently
enough to prevent woody growth and removal of sediment from the pre-treatment device.
Despite careful design, construction and maintenance, trenches eventually clog. Studies in
Maryland suggest the longevity of trenches may be 10-15 years (Schueler, 1987).
A survey in Maryland of infiltration devices four to six years after construction found only 53%
of the infiltration trenches were functioning as designed. The main problem with the trenches
were excessive sediment loads and clogging (Lindsey, 1991).
Porous Pavement
Porous pavement, an alternative to conventional pavement, reduces much of the need for
drainage conveyance and treatment of the runoff from the pavement area. Instead, runoff is
diverted through a porous asphalt layer into an underground stone reservoir. Porous pavement
has a layer of porous top course covering an additional layer of gravel. A crushed stone-filled
groundwater recharge bed is typically installed beneath these top layers. Runoff infiltrates
through the porous asphalt layer and into the underground recharge bed. The runoff then
exfiltrates out of the recharge bed into the underlaying soils or into a perforated pipe system.
Porous pavement cannot be used where there are high traffic volumes or heavy truck traffic.
This typically restricts porous pavement use to low volume parking areas. Also, porous
pavement is only feasible on sites with gentle slopes.
Porous pavement and recharge beds are usually designed to receive runoff from structures and/or
other paved surfaces through a system of pipes or other conveyance system. However, porous
pavement should not receive runoff from pervious areas, such as lawns. In fact, porous
pavement must be combined with other overall site drainage engineering that carefully directs
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any sediment or particulate laden runoff away from porous pavement surfaces (Cahill, 1991).
Also, there must be at least four feet of permeable soil (SCS soil group A or B) between the
bottom of the recharge bed and bedrock or highwater table.
The main factors that influence the removal efficiency are the storage volume, basin surface
area, and soil percolation rates.
Any runoff that percolates into the ground and reaches surface waters through the ground water
is commonly assumed to have had the pollutants removed by soil processes such as filtration and
biological action. Therefore, any runoff and pollutants that percolate into the ground are
estimated as being removed. The validity of this assumption depends on the pollutants of
concern, their chemical properties and local conditions.
To date the prime criticism of porous pavement has been its clogging due to sedimentation,
especially during the construction phase but also after-construction (Cahill, 1991). If the
pavement becomes clogged it is difficult and costly to rehabilitate (Schueler, 1987).
A study conducted in Maryland found that of 13 porous pavement sites that had been constructed
four to six years earlier, only 2 facilities were functioning as designed. 11% of the sites had
problems with clogging of the facility and 69% had excessive sediment or debris (Lindsey,
1991). Many states no longer promote the use of porous pavement because it tends to clog with
fine sediments. (Washington Department of Ecology, 1991).
There may also be problems with the use of porous pavement in cold climates since sand, ash,
or deicing salts used for snow removal should never be applied to porous pavement. However,
reports have shown that snow and ice melt more quickly on porous pavement. Porous pavement
is also more susceptible to freeze-thaw damage than conventional pavement (SWRPC, 1991).
Operation and Maintenance
Routine maintenance of porous pavement includes having the surface vacuum swept followed
by high pressure jet hosing at least four times per year to keep the asphalt pores open. In
addition, the site should be inspected after every major storm event for the first few months after
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construction and annually thereafter, and potholes and cracks can be replaced using conventional
asphalt if the replaced area does not exceed 10% of the total area. Spot clogging can be treated
by drilling holes into the asphalt layer. However, if the facility becomes completely clogged it
can only be maintained with complete replacement (Schueler, 1987).
Concrete Grid Pavement
Concrete grid pavement, sometimes referred to as "grasscrete," consists of concrete blocks with
regularly interspersed void areas which are filled with pervious materials such as gravel, sand
or grass. The blocks are typically place on a sand and gravel base and designed to provide a
load-bearing surface that is adequate to support vehicles, while allowing infiltration of surface
water into the underlying soil.
As with porous pavement, concrete grid pavement should be used in areas with low traffic
volume. Suggested uses are low volume parking spaces, multi-use open space, fire lanes and
stream banks/lakeside erosion protection. In addition, concrete grid pavement with grass require
at least five hours of sunlight daily for most grass species to survive. Also, there must be at
least four feet of permeable soil (SCS soil group A or B) between the sand and gravel base and
bedrock or high water table.
Concrete grid pavement offers an alternative means in providing load-bearing surfaces without
greatly increasing the impervious areas. The main factor that influences the reduction in runoff
volume and provides pollutants removal are the amount of open spaces, the slope of the concrete
grid pavement; and the underlying soil infiltration rate.
Runoff that percolates into the ground and reaches surface water through the groundwater is
commonly assumed to have had pollutants removed by soil processes such as filtration and
biological action. Therefore, any runoff and pollutants that percolate into the ground are
assumed to be removed. The validity of this assumption depends on the pollutants of concern,
their chemical properties and local conditions.
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Operation and Maintenance
Like all infiltration practices, concrete grid pavement requires maintenance to prevent clogging
of the system. In addition, concrete grid pavement with grass requires additional "normal" grass
maintenance, such as mowing, watering and fertilizing. However, extra care should be taken
when applying fertilizers and pesticides that may have adverse an adverse effect on concrete
products.
With proper maintenance, the life span of concrete grid pavements can be comparable to that
of asphalt pavements which is 20 years (Smith, 1981).
Filtration Basins and Sand Filters
Filtration basins and sand filters are basins that are lined with a filter media (such as sand and
gravel). Stormwater runoff drains through the filter media and into perforated pipes that are
located in the filter media. Detention time is typically 4 to 6 hours (City of Austin, 1990). The
runoff typically requires some form of preliminary treatment such as sedimentation. Hence,
sediment trapping structures are required for sedimentation to prevent premature clogging of the
filter media.
Filtration basins have been used for drainage areas from 3 to 80 acres (City of Austin, 1990).
The underdrain pipe system is intended to improve the perculation rate of the soil and/or control
the water table elevation. Consequently, filtration basins may be used on sites with impermeable
soils (SCS soil group C and D) since the runoff filters through specially placed filter media and
pipe system, not native soils. In addition, a filtration basin's underdrain pipes may lower the
water table in its immediate vicinity, and therefore may be used where water table conditions
would not allow sufficient infiltration (Livingston, 1988).
The main factors that influence the removal rate are the storage volume, filter media, and
detention time.
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Operation and Maintenance
Maintenance requirements include inspecting the basin after every major storm for the first few
months after construction and annually thereafter, removing litter and debris and revegetating
eroded areas. In addition, the accumulated sediment should be periodically removed and the
filter media with sediment depositions should be removed and replaced.
Water Quality Inlet - Catch Basin
Catch basins are the simplest form of a water quality inlet. Catch basins are typical single-
chambered stormwater inlets except that the bottom of the structure has been lowered to provide
2 to 4 feet between the outlet pipe and structure bottom. This provides a permanent pool of
water where sedimentation can occur (City of Austin, 1988).
Operation and Maintenance
To perform properly, catch basins must be cleaned and the accumulated sediment removed. The
required frequency of cleaning is dependent on the storage volume and volume of sediment
entering the catch basin. A typical cleaning frequency is approximately 4 times a year.
However, no acceptable clean-out and disposed techniques currently exist (Schueler et al, 1992).
With proper maintenance, a catch basin should have at least a 50-year life span. However, if
the accumulated sediment is not removed it may be resuspended during a storm and actually
increase the pollutant load from an individual storm.
Water Quality Inlet - Catch Basin With Sand filter
Catch basins with sand filter are a variation of "one" chamber catch basins. They consist of two
chambers, a sedimentation chamber and filtration chamber that is filled with sand. The runoff
first enters the sedimentation chamber that provides effective removal of coarse particles, which
helps prevent pre-mature clogging of the filter media. It also provides sheet flow into the
filtration chamber that will prevent scouring of filter media (Shaver, 1991). As runoff enters
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the filtration chamber additional pollutant removal of finer suspended solids is achieved through
filtering.
Catch basins with sand filters are typically used in highly impervious areas with drainage areas
less than 5 acres. For larger drainage areas with mixed ground covers filtration basins are used
and function on the same principals. Catch basins with sand filters can also be used to retrofit
of small impervious areas that generate high loads.
Operation and Maintenance
Catch basins with sand filters should be annually inspected and periodically the top layer of sand
and deposited sediment should be removed and replaced. In addition, periodically the
accumulated sediment in the sedimentation chamber should be removed (Shaver, 1991).
However, no acceptable clean-out and disposed techniques for the accumulated sediment
currently exist (Schueler et al, 1992).
With proper maintenance and replacement of the sand, the catch basin with sand filter should
have at least a 50-year life span.
Water Quality Inlet - Oil/Grit Separator
Oil/grit separators come in many configurations. A common configuration is the 3-chamber
oil/grit separator. The first chamber is the sedimentation chamber that allows for sedimentation
of coarse material and screening of debris, the second chamber provides separation of oil, grease
and gasoline, and third chamber is provided to prevent any possibility of a surcharge pressure
from occurring and as a safety relief for the structure if a blockage occurs.
An oil/grit separator should be used in areas receiving high hydrocarbon loadings such as gas
stations, loading areas and parking lots. The maximum drainage area to this type of water
quality inlet is typically one acre. They are also appropriate for retrofit of small areas that
generate high loads of sediment or hydrocarbons such as gas stations and fast food parking lots.
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The main factors that influence removal efficiencies are the storage volume for the chambers,
design configuration and maintenance frequency.
Operation and Maintenance
The degree and frequency of maintenance will significantly affect the performance of oil-water
separator. Cleaning the oil/grit separators at regular intervals will prevent the accumulated
debris and oil to be discharged from the structure during intense storms. An oil/grit separator
typically should be cleaned at least four times a year. However, no acceptable clean-out and
disposed techniques currently exist (Schueler et al, 1992).
With proper maintenance the oil/grit separator should have at least a 50-year life span.
However, if the accumulated sediment is not removed it may be resuspended during a storm and
actually increase the pollutant load from an individual storm.
5.2 SUMMARY OF ADVANTAGES, DISADVANTAGES, EFFECTIVENESS
AND COST
This section presents summary tables (Tables 5-1, 5-2, and 5-3) for various management
practices. The information presented in this section is summarized in the following tables:
• Table 5-1 summarizes the advantages and disadvantages of the various
management practices.
• Table 5-2 summarizes the effectiveness of the various management practices.
Effectiveness was defined as the percent pollutant removal that the practice
achieves if properly designed, constructed and maintained. There are many
pollutants found in urban runoff and the effectiveness can be measured for each
of the pollutants. Researchers have not come to a consensus as to what pollutants
are the best to use for measuring effectiveness. However the pollutants that
appear to be of most concern are Total Suspend Solids (TSS), Total Phosphorus
(TP), Total Nitrogen (TN), Chemical Oxygen Demand (COD), Lead (Pb), and
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Zinc (Zn). Therefore, management practices' effectiveness for these pollutants
are tabulated in Table 5-2.
Pollutant removal is achieved through complex chemical, biological, and physical
processes. Due to the complexity of the processes and their dependence on a
large variety of parameters, researchers have not come to a consensus as to the
effectiveness of the practices. Therefore, Table 5-2 presents the effectiveness
information and includes the average and range observed in the reviewed
literature, the probable range expected from a properly designed and maintained
practice based on the literature and issues discussed in Section 5.3, and the
references considered in developing the data.
During the literature search for this project, it was apparent that there have been a limited
number of monitoring studies completed regarding the effectiveness of these management
practices. The results of the studies that were available are summarized in Table 5-2. However,
performance monitoring studies are difficult to compare due to the differences in the studies.
The following variables are involved in BMP performance monitoring (Schueler, 1992):
• Number of storms monitored;
• Type and size of storm monitored;
• BMP design variations;
• Monitoring technique used;
• Pollutant removal calculation technique used;
• Seasons monitored; and
• Characteristics of contributing watershed.
It is also difficult to quantify the pollutant removal capabilities of a BMP because the
performance varies from storm to storm. The pollutant removal capabilities of a BMP will also
vary during the BMP's lifetime (Schueler, 1992).
80040000H:\WPYReport\Roads\Chap5.new
Roads, Highway & Bridges
5-19
Woodward-Clyde
January 29, 1993
-------
50 oo
TABLE 5-1. ADVANTAGES AND DISADVANTAGES OF MANAGEMENT PRACTICES1
MANAGEMENT
PRACTICE
ADVANTAGE
DISADVANTAGE
Infiltration Basin
• Provides groundwater recharge
• Can serve large developments
• High removal capability for particulate pollutants and moderate
removal for soluble polluunts
• When basin works, it can replicate predevelopment hydrology
more closely than other BMP options
• Basins provide more habitat value than other infiltration systems
• Possible risk of contaminating groundwater
• Only feasible where soils permeable and have sufficient
depth to rock and water table
• Fairly high failure rate
• If not adequately maintained can be eyesore, breed mosquitos
and create undesirable odors
• Regular maintenance activities cannot prevent rapid clogging
of infiltration basins
Infiltration Trench
• Provides groundwater recharge
* Can serve small drainage areas
* Can fit into medians, perimeters and other unutilized areas of a
development site
• Helps replicate predevelopment hydrology, increases dry
weather baselfow, and reduces bankfull flooding frequency
• Possible risk of contaminating groundwater
• Only feasible where soils permeable and have sufficient
depth to rock and water table
• Since not as visible as other BMPs, less likely to be
maintained by residents
• Requires significant maintenance
Vegetative Filter Strip (VFS)
• Low maintenance requirements
• Can be used as part of the runoff conveyance system to provide
pre-treatment
• Can effectively reduce particulate pollutant levels in areas where
runoff velocity is low to moderate
• Promotes groundwater recharge, urban wildlife habitat, and
stream bank stabilization
• Economical
• Often concentrates water, which significantly reduces
effectiveness
• Ability to remove soluble pollutants highly variable
• Limited feasibility in highly urbanized areas where runoff
velocities are high and flow is concentrated
• Requires periodic repair, regrading, and sediment removal to
prevent channelization
Grassed Swale
• Requires minimal land area
• Can be used as part of the runoff conveyance system to provide
pretreatment
• Can provide sufficient runoff control to replace curb and gutter
in single-family residential subdivisions and on highway
medians
• Economical
• Low slope swales can create wetland habitat
• Low pollutant removal rates
• Leaching from culverts and fertilized lawns may actually
increase the presence of trace metals and nutrients
• Requires more land than curb and gutter
• Can impact on groudwater quality in certain situations
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TABLE 5-1 ADVANTAGES AND DISADVANTAGES OF MANAGEMENT PRACTICES1 (Cont'd)
MANAGEMENT
PRACTICE
ADVANTAGE
DISADVANTAGE
Porous Pavement
• Provides groundwater recharge
• Provides water quality control without additional consumption
of land
• Can provide peak flow control
• High removal rates for sediment, nutrients, organic matter, and
trace metals
• When operating properly can replicate predevelopment
hydrology
• Eliminates the need for stormwater drainage, conveyance, and
treatment systems off-site
• Requires regular maintenance
• Possible risk of contaminating groundwater
• Only feasible where soil is permeable, there is sufficient
depth to rock and water table, and there are gentle slopes
• Not suitable for areas with high traffic volume
• Need extensive feasibility tests, inspections, and very high
level of construction workmanship (Schueler, 1987)
• High failure rate due to clogging
• Not suitable to serve large off-site pervious areas
Concrete Grid Pavement
• Can provide peak flow control
• Provides groundwater recharge
• Provides water quality control without additional consumption
of land
* Requires regular maintenance
* Not suitable for area with high traffic volume
* Possible risk of contaminating groundwater
* Only feasible where soil is permeable, there is sufficient
depth to rock and water table, and there are gentle slopes
Sand Filter/Filtration Basin
• Ability to accommodate medium size development (3-80 acres)
o Flexibility to provide or not provide groundwater recharge
• Can provide peak volume control
• Can be used in areas where groundater quality concerns
precludes the use of infiltration
• Requires pretreatment of stormwater through sedimentation
to prevent filter media from premature clogging
• Larger designs without grass covers may not be attractive in
residential areas
• Do not provide significant stormwater detention for
downstreams areas
Water Quality Inlets
• Provides high degree of removal efficiencies for larger particles
and debris as pre-treatment
• Requires minimal land area
• Flexibility to retrofit existing small drainage areas and
applicable to most urban areas
• Not feasible for drainage area greater than 1 acre
• Marginal removal of small particles, heavy metals and
organic pollutants
• Not effective as water quality control for intense storms
• Minimal nutrient removal
Water Quality Inlet
with Sand Filler
• Provides high removal efficiencies on particulates
• Requires minimal land area
• Flexibility to retrofit existing small drainage areas
• Higher removal of nutrient as compared to catch basins and
oil/grit separator
• Not feasible for drainage area greater than 5 acres
• Only feasible for areas that are stabilized and highly
impervious
• Not effective as water quality control for intense storms
-------
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TABLE 5-1 ADVANTAGES AND DISADVANTAGES OF MANAGEMENT PRACTICES1 (Cont'd)
MANAGEMENT
PRACTICE
ADVANTAGE
DISADVANTAGE
Oil/Grit Separator
* Captures coarse-grained sediments and some hydrocarbons
* Requires minimal land area
* Flexibility to retrofit existing small drainage areas and
applicable lo most urban areas
* Shows some capacity to trap trash, debris, and other floatables
* Can be adapted to all regions of the country
* Not feasible for drainage area greater than 1 acre
* Minimal nutrient and organic matter removal
• Not effective as water quality control for intense storms
* Concern exists over the pollutant toxicity of tapped residuals
• Require high maintenance
• Pulse hydrocarbon loads may result from resuspension
during large storms
Extended Detention
Dry Pond
• Can provide peak flow control
• Possible to provide good particulates removal
• Can serve large development
• Requires less capital cost and land area when compared to wet
pond
• Does not generally release warm or anoxic water downstream
• Provides excellent protection for downstream channel erosion
• Can create valuable wetland and meadow habitat when properly
landscaped
* Removal rates for soluble pollutants are quite low
* Not economical for drainage areas less than 10 acres
* If not adequately maintained can be eyesore, breed mosquitos
and create undesirable odors
Wet Pond
• Can provide peak flow control
• Can serve large developments, most cost effective for larger
more intensively developed sites
• Enhance aesthetic and provide recreational benefits
• Little groundwater discharge
• Permanent pool in wet ponds helps to prevent scour and
resuspension of sediments
• Provides moderate to high removal of both particulate and
soluble urban stormwaler pollutants
• Creates wildlife habitat
• Very useful in both low and high visibility commercial and
residential development
* Not economical for drainage area less than 10 acres
* Potential safety hazards if not properly maintained
* If not adequately maintained can be eyesore, breed mosquitos
and create undesirable odors
* Requires considerable space which limits their use in densely
urbanized areas with expensive land and property values
* Not suitable for hydrologic soil group "A" and "B" (SCS
classification)
* With possible thermal discharge and oxygen depletion, may
severely impact downstream aquatic life
Extended Detention
Wet Pond
• Can provide peak flow control
• Can serve large developments, most cost effective for larger
more intensively developed sites
• Enhance aesthetic and provide recreational benefits
• Permanent pool in wet ponds helps to prevent scour and
resuspension of sediments
• Provide better nutrient removal when compared lo wet pond
• Creates wildlife habitat
• Not economical for drainage area less than 10 acres
• Potential safety hazards if not properly maintained
• If not adequately maintained can be eyesore, breed mosquitos
and create undesirable odors
• Requires considerable space which limit9 their use in densely
urbanized areas with expensive land and property values
• Not suitable for hydrologic soil group "A" and "B" (SCS
classification)
• With possible thermal discharge and oxygen depletion, may
severely impact downstream aquatic life
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TABLE 5-1 ADVANTAGES AND DISADVANTAGES OF MANAGEMENT PRACTICES1 (Cont'd)
MANAGEMENT
PRACTICE
ADVANTAGE
DISADVANTAGE
Constructed Stormwater Wetland
• Can serve large developments, most cost effective for larger
more intensively developed sites
• Provides peak flow control
• Enhance aesthetic and provide recreational benefits
• The marsh fringe also protects shoreline from erosion
• Permanent pool in wet ponds helps to prevent scour and
resuspension of sediments
• Has high pollutant removal capability
• Creates wildlife habitat
• Not economical for drainage area less than 10 acres
• Potential safety hazards if not properly maintained
• If not adequately maintained can be eyesore, breed mosquitos
and create undesirable odors
• Requires considerable space which limits their use in densely
urbanized areas with expensive land and property values
• With possible thermal discharge and oxygen depletion may
severely impact downstream aquatic life
• May contribute to nutrient loadings during die-down periods
of vegetations
Several items taken from Schucher et al, 1992.
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-------
TABLE 5-2 EFFECTIVENESS OF MANAGEMENT PRACTICES FOR CONTROL OF RUNOFF FROM NEWLY DEVELOPED AREAS
MANAGEMENT
% REMOVAL
MAIN
REFERENCES
PRACTICE
REMOVAL
TSS
TP
TN
COD
Pb
Zn
EFFICIENCY
FACTORS
INFILTRATION BASIN: Ave:
75
65
60
65
65
65
• Soil
Schueler, 1987; EPA, 1983;
percolation
Woodward-Clyde, 1986
Reported Range:
45-100
45-100
45-100
45-100
45-100
45-100
rates
• Basin surface
Probable Range (1):
area
• Storage
SCS Soil Group A
60-100
60-100
60-100
60-100
60-100
60-100
Volume
SCS Soil Group B
50-80
50-80
50-80
50-80
50-80
50-80
No. Values Considered:
7
7
7
4
4
4
INFILTRATION Ave:
75
60
55
65
65
65
• Soil
Schueler, 1987; EPA, 1983;
TRENCH:
percolation
Woodward-Clyde, 1986; Kuo,
Reported Range:
45-100
40-100
(-10)-100
45-100
45-100
45-100
rates
etal, 1988; Lugbill, 1990
• Trench
Probable Range (2):
surface area
* Storage
SCS Soil Group A
60-100
60-100
60-100
60-100
60-100
60-100
Volume
SCS Soil Group B
50-90
50-90
50-90
50-90
50-90
50-90
No. Values Considered:
9
9
9
4
4
4
VEGETATIVE FILTER Ave:
65
40
40
40
45
60
• Runoff
IEP, 1991; Casman, 1990;
STRIP
volume
Glick, et al, 1991; VA Dept.
Reported Range:
20-80
0-95
0-70
0-80
20-90*
30-90"
• Slope
of Cons., 1987; Minnesota
• Soil
PCA, 1989; Schuler, 1987;
Probable Range (3):
40-90
30-80
20-60
-
30-80
20-50
infiltration
Hartigan, et al, 1989
rates
No. Values Considered:
7
4
3
2
3
3
• Vegetative
cover
• Buffer length
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TABLE 5-2 EFFECTIVENESS OF MANAGEMENT PRACTICES FOR CONTROL OR RUNOFF FROM NEWLY DEVELOPED AREAS (Cont'd)
MANAGEMENT
% REMOVAL
MAIN
REFERENCES
PRACTICE
REMOVAL
TSS
TP
TN
COD
Pb
Zn
EFFICIENCY
FACTORS
GRASSED SWALES Ave:
60
20
10
25
70
60
• Runoff
Yousef, et al, 1985; Dupuis,
Volume
1985; Washington State,
Reported Range:
0-100
0-100
0-40
25
3-100*
50-60*
• Slope
1988; Schueler, 1987; British
• Soil
Columbia Res. Corp., 1991;
Probable Range (4):
20-40
20-40
10-30
-
10-20
10-20
infiltration
EPA, 1983; Whalen, et al,
rates
1988; Pitt, 1986; Casman,
No. Values Considered:
10
8
4
1
10
7
• Vegetative
1990
cover
• Swale length
• Swale
geometry
POROUS PAVEMENT Ave:
90
65
85
80
100
100
• Percolation
Schueler, 1987
rates
Reported Range:
80-95
65
80-85
80
100
100
• Storage
volume
Probable Range:
60-90
60-90
60-90
60-90
60-90
60-90
No. Values Considered:
2
2
2
2
2
2
CONCRETE GRID Ave:
90
90
90
90
90
90
• Percolation
Day, 1981; Smith, et al, 1981
PAVEMENT
rates
Reported Range:
65-100
65-100
65-100
65-100
65-100
65-100
Probable Range:
60-90
60-90
60-90
60-90
60-90
60-90
No. Values Considered:
2
2
2
2
2
2
SAND Ave:
80
50
35
55
60
65
• Treatment
City of Austin, 1988;
FILTER/FILTRATION
volume
City of Austin, 1990
BASIN Reported Range:
60-95
0-90
20-40
45-70
30-90
50-80
• Filtration
media
Probable Range:
60-90
0-80
20-40
40-70
40-80
40-80
No. Values Considered:
10
6
7
3
5
5
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O | TABLE 5-2 EFFECTIVENESS OF MANAGEMENT PRACTICES FOR CONTROL OR RUNOFF FROM NEWLY DEVELOPED AREAS (Cont'd)
MANAGEMENT
% REMOVAL
MAIN
REFERENCES
PRACTICE
REMOVAL
TSS
TP
TN
COD
Pb
Zn
EFFICIENCY
FACTORS
WATER QUALITY
Ave:
35
5
20
5
15
5
* Maintenance
Pitt, 1986; Field, 1985;
INLET(7)
Schueler, 1987
Reported Range:
0-95
5-10
5-55
5-10
10-25
5-10
• Sedimentation
storage
Probable Range:
10-25
5-10
5-10
5-10
10-25
5-10
volume
No. Values Considered:
3
1
2
1
2
1
WATER QUALITY
Ave:
80
NA
35
55
80
65
• Sedimentation
Shaver, 1991
INLET WITH SAND
storage
FILTER (7)
Reported Range:
75-85
NA
30-45
45-70
70-90
50-80
volume
Probable Range:
70-90
_
30-40
40-70
70-90
50-80
• Depth of filter
media
No. Values Considered:
1
0
1
1
1
1
OIL/GRIT SEPARATOR
Ave:- _
15
5
5
5
15
5
• Sedimentation
Schueler, 1987
(7)
storage
Reported Range:
0-25
5-10
5-10
5-10
10-25
5-10
volume
Probable Range:
10-25
5-10
5-10
5-10
10-25
5-10
• Outlet
configurations
Number of References
2
1
1
1
1
1
EXTENDED
Ave:
45
25
30
20
50
20
• Storage
MWCOG, 1983; City of
DETENTION
volume
Austin, 1991; Schueler and
DRY POND
Reported Range:
5-90
10-55
20-60
0-40
25-65
(-40)-65
• Detention
Helfrich, 1988; Pope and
time
Hess, 1988; OWML, 1987;
Probable Range (5):
70-90
10-60
20-60
30-40
20-60
40-60
• Pond shape
Bait. Dept. P.W., 1989, cited
in Schueler et al, 1992
No. Values Considered:
6
6
4
5
4
5
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~•also reported as 50% TSS removed
(1) Design Criteria: Storage volume equals 90% ave. runoff volume, completely drain within 72 hours; maximum depth = 8 ft; minimum depth = 2 ft.
(2) Design Criteria: Storage volume equals 90% ave. runoff volume, completely drain with in 72 hours; maximum depth = 8 ft; minimum depth = 3 ft;
trench volume.
(3) Design Criteria: Flow depth < 0.3 ft., travel time > S min.
(4) Design Criteria: Low slope and adequate length
(5) Design Criteria: Min. E.D. time 12 hours
storage volume = 40% excavated
-------
i
to
00
TABLE 5-2 EFFECTIVENESS OF MANAGEMENT PRACTICES FOR CONTROL OR RUNOFF FROM NEWLY DEVELOPED AREAS (Cont'd)
(6) Design Criteria: Minimum area of wetland equal 1 % of drainage area
(7) No information was available on the effectiveness of removing grease or oil
NA: Not Available
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• Table 5-3 presents construction and annual maintenance cost information. In this
table, the cost information is annualized so that comparisons can be made from
one practice to another. To analyze the cost an interest rate of 5 % was assumed.
Some practices have limited useful lives. However, other practices will continue
to provide water quality benefits indefinitely if properly maintained. In order to
analyze the capital costs of those practices, they were assumed to have a useful
life of 50 years. The costs are presented to give planners an idea of the cost of
a practice relative to another and are not recommended for use in estimating or
bidding construction costs.
These summary tables are based on the detailed cost and effectiveness data presented in the
Appendix. Additional effectiveness and cost information follows the tables in Section 5.3 and
5.4.
80040000H:\WP\ReportVRoads\Chap5.new
Roads, Highway & Bridges
5-29
Woodward-Clyde
January 29, 1993
-------
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TABLE 5-3. COST OF MANAGEMENT PRACTICES FOR CONTROL OF RUNOFF FROM NEWLY DEVELOPED AREAS
PRACTICE
LAND
REQUIRE-
MENT
CONSTRUCTION
COST
USEFUL
LIFE
ANNUAL
O&M
TOTAL ANNUAL COST
REFERENCES
INFILTRATION
BASIN
High
Ave: $0.5/ cu. ft. storage
Probable Cost: $0.4 - $0.7/cu. ft.
Reported Range: $0.2 - $1.2/ cu. ft.
25«>
Ave: 7% of capital cost
Reported Range: 3% - 13% of capital cost
$0.03 - $0.05/ cu. ft.
Wiegand, et al,
1986; SWRPC,
1991
INFILTRATION
TRENCH
Low
Ave: $4.0/ cu. ft. storage
Probable Cost: $2.5 - $7.5/cu. ft.
Reported Range: $0.9 - $9.2/ cu. ft.
10<'>
Ave: 9% of capital cost
Reported Range: 5% - 15% of capital cost
$0.3 - $0.9/cu. ft.
Wiegand, et al,
1986; Macal, et al,
1987; SWRPC,
1991; Kuo, et al,
1988
VEGETATIVE
FILTER STRIP
Varies
Established from existing vegetation-
Ave: $0
Reported Range: $0
Established from seed-
Ave: $400/ acre
Reported Range: $200 - $1,000/ acre
Established from Seed & Mulch-
Ave: $1,500/ acre
Reported Range: $800 - $3,500/ acre
Established from sod-
Ave: $11,300/ acre
Reported Range: $4,500 - $48,000/acre
50*
Natural Succession Allowed to Occur-
Ave: $100/ acre
Reported Range: $50 - $200/ acre
Natural Succession Not Allowed to Occur-
Ave: $800/ acre
Reported Range: $700 - $900/ acre
Natural Succession
Allowed To Occur-
Established from-
Natural Vegetation: $100/
acre
Seed: $125/ acre
Seed & Mulch: $200/ acre
Sod: $700/ acre
Natural Succession Not
Allowed To Occur-
Established from:
Natural Vegetation: $800/
acre
Seed: $825/ acre
Seed & Mulch: $900/ acre
Sod: $1,400/ acre
Schueler, 1987;
SWRPC, 1991
GRASSED SWALES
Low
Established from seed:
Ave: $6.5/ lin. ft.
Reported Range: $4.5 - $8.5/ lin ft.
Established from sod:
Ave: $20/ lin. ft.
Reported Range: $8 - $50/ lin. ft.
50*
Established From Seed or Sod-
Ave: $0.75/ lin. ft.
Reported Range: $0.5 - $1.0/ lin. ft.
Established From Seed:
$1/ lin. ft.
Established From Sod:
$2/ lin. ft.
Schueler, 1987;
SWRPC, 1991
POROUS
PAVEMENT
None
Ave: $1.5/ sq. ft.**
Reported Range: $1 - $2/ sq. ft.**
10<3>
Ave: $0.01/ sq. ft.**
Reported Range: $0.01/ sq. ft.**
0.15/ sq. ft.**
SWRPC, 1991;
Schueler, 1987
CONCRETE GRID
PAVEMENT
None
Ave: $1/ sq. ft.**
Reported Range: $1 - $2/ sq. ft.**
20
Ave: (-$0.04)/sq. ft.**
Reported Range: (-$0.04)/ sq. ft.**
0.05/ sq. ft.**
Smith, 1981
-------
TC oo
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TABLE 5-3. COST OF MANAGEMENT PRACTICES FOR CONTROL OF RUNOFF FROM NEWLY DEVELOPED AREAS (Cont'd)
a 8
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PRACTICE
LAND
REQUIRE-
MENT
CONSTRUCTION
COST
USEFUL
LIFE
ANNUAL
O&M
TOTAL ANNUAL COST
REFERENCES
SAND FILTER/
FILTRATION BASIN
High
Ave: $5/ cu. ft.
Probable Cost: $2 - $9/cu. ft.
Reported Range: $1 - $ll/cu. ft.
25®
Ave: Not Available
Probable Cost: 1% of construction cost
Reported Range: Not Available
$0.1 - $0.8/cu. ft.
Tull, 1990
WATER QUALITY
INLET
None
Ave: $2,000/ each
Reported Range: $1,100- $3,000/each
50
Ave: $30/each")
Reported Range: $20-40/eachf4>
$150/each
SWRPC, 1991
WATER QUALITY
INLET WITH SAND
FILTERS
None
Ave: $10,000/ drainage acre
Reported Range: $10,000/ drainage acre
50
Ave: Not Available
Probable Cost: $100/ drainage acre
Reported Range: Not Available
$700/ drainage acre
Shaver, 1991
OIL/GRIT
SEPARATOR
None
Ave: $18,000/ drainage acre
Reported Range: $15,000 - $20,000/
drainage acre
50
Ave: $20/ drainage acre'4'
Reported Range: $5 - $40/ drainage acre'4'
$1,000/ drainage acre
Schueler, 1987
EXTENDED
DETENTION DRY
POND
High
Ave: $0.5/ cu. ft. storage
Probable Cost: $0.09 - $5/cu. ft.
Reported Range: $0.05 - $3.2/ cu. ft.
50
Ave: 496 of capital cost
Reported Range: 3% - 5% of capital cost
$0,007 - $0.3/cu. ft.
APWA Res.
Foundation
WET POND AND
EXTENDED
DETENTION WET
POND
High
Storage Volume < 1,000,000 cu. ft.:
Ave: $0.5/ cu. ft. storage
Probable Cost: $0.5 - $l/cu. ft.
Reported Range: $0.05 - $1.0/ cu. ft.
Storage Volume > 1,000,000 cu. ft.:
Ave: $0.25/ cu. ft. storage
Probable Cost: $0.1 - $0.5/cu. ft.
Reported Range: $0.05 - $0.5/ cu. ft
50
Ave: 3% of capital cost
Probable Cost:
< 100,000 cu. ft. = 5 % of capital cost
> 100,000 & <1,000,000 cu. ft = 3%
of capital cost
> 1,000,000 cu. ft. = 1 % of capital cost
Reported Range: 0.1 % - 5% of capital
cost
$0,008 - $0.07/cu. ft.
APWA Res.
Foundation;
Wiegand, et al,
1986; Schueler,
1987; SWRPC,
1991
CONSTRUCTED
STORMWATER
WETLANDS
High
Ave: Not available
Reported Range: Not available
50*
Ave: Not Available
Reported Range: Not Available
Not available
i
c
*
3
o
o
a.
$
N> ES
no a.
so <<
so a.
W CD
* Useful life taken as life of project, assumed to be 50 years.
** Incremental Cost, i.e. cost beyond that required for conventional asphalt pavement
(1) References indicate the useful life for Infiltration Basins and Infiltration Trenches are between 25-50 and 10-15 years respectively. Due to the high failure rate, infiltrations basins are assumed to have
useful life span of 25 years in infiltration trenches are assumed to have useful life span of 10 years.
(2) Since no information was available for useful life of Filtration Basins they were assumed to be similar to Infiltration Basins.
(3) Since no information was available for useful life of Porous Pavement it was assumed to be similar to that of Infiltration Trenches.
(4) Frequency of Cleaning assumed 2 times per year.
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5.3 EFFECTIVENESS
Factors that influence the effectiveness of the various management practices are shown in Table
5-2. Effectiveness is defined as the percent pollutant removal that the practice achieves if
properly designed, constructed and maintained. Regional and site specific factors such as
rainfall amount and duration, vegetation type, soil type and drainage area influence the
effectiveness of a practice and are discussed as appropriate. The data analyzed to draw the
following effectiveness conclusions are presented in Appendix A.
5.3.1 Highways and Roads
Vegetative Filter Strip
Properly designed and functioning vegetative filter strips effectively remove particulates such as
sediment, organic matter and many trace metals by the filtering action of the grass and
deposition. Removal of soluble pollutants is achieved by infiltration into the soil and is probably
not very effective since typically only a small portion of the runoff infiltrates. Forested filter
strips appear to be more effective than grassed strips, but a longer length is required for optimal
removal rates (Schueler, 1987).
The pollutant removal rates of vegetative filter strips can be increased by increasing the travel
time and decreasing the flow depth. Factors that affect the travel time and flow depth are
drainage area, slope, length and type of vegetative cover (Dorman et al, 1989).
Several sources of information on urban vegetative filter strips (VFSs) and several on agriculture
VFSs were obtained. Most of the reports gave removal rates for a specific VFS slope and
length. In order to provide probable removal rates that could be used at the planning level,
Table 5-2 was developed from the chart prepared by Dorman et al, 1989 for the Federal
Highway Administration (FWHA).
The FHWA report (Dorman, 1989) is based on research and monitoring done for highways.
However, the removal mechanisms and rates of VFSs should be the same on highway sites as
on urban sites and therefore are applicable. In order to estimate removal rates probably
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provided from properly designed urban VFSs using the chart prepared by Dorman et al, the
depth of flow was assumed to be less than 4 inches. This would be appropriate for almost all
VFSs since they are designed for sheet flow and not concentrated flow. The travel time was
assumed to be greater than 5 minutes, which also should be appropriate for correctly designed
VFSs, since the strip should have a low slope and adequate length.
The total suspended solids (TSS) removal efficiency range was read from the chart. In addition,
the research indicated that the lead removal rate is approximately 90% of the TSS removal rate
and zinc removal is approximately 60% of TSS.
These removal efficiency ranges are similar to the reported ranges in the other references. The
report indicated that total phosphorous (TP) and total nitrogen (TN) removal rates could not be
easily related to depth of flow and travel time. Therefore, TP and TN removal rates for Table
5-2 were taken as the range from the other references, excluding turf strips.
It must be noted that the cited removal rates are based on ideal conditions - evenly distributed
sheet flow and a dense, vigorous vegetative cover. However, if the water concentrates, removal
rates can be significantly less and if eroded gullies form the vegetative filter strip could actually
be a source of sediment.
Grassed Swales
Properly designed and functioning grassed swales provide some pollutant removal through
filtering by vegetation of particulate pollutants, biological update of nutrients and infiltration of
runoff. However, because the flow is concentrated the removal rates are low (SWRPC, 1991).
In general swales are not effective in removing soluble pollutants. Also, in some cases trace
metals have leached from swale culverts and nutrients have leached from fertilizers.
Consequently, these pollutant concentrations have actually increased (Schueler, 1987).
To have significant pollutant removal rates, grassed swales must have long hydraulic travel times
and low flow depth. This is often achieved along highways where there are long lengths of
grassed swales. However, along urban roads where travel lengths are typically short, removal
rates are low.
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The pollutant removal rates of grass channels can be increased by increasing the travel time and
decreasing the flow depth. Factors that affect the travel time and flow depth are drainage area,
slope, length, swale width and slide slopes and type of vegetative cover (Dorman 1989).
The probable removal rates for grassed swales were obtained from the above chart discussed for
vegetative filter strips. The removal efficiency for grassed swales along roads and highways is
higher than for grassed swales in other urban areas, because they are typically much longer and
therefore have longer travel times.
Several sources of information on grassed swales were reviewed. However, the reported percent
removal for TSS varied from 0 to >99%. These differences are most likely due to differences
in the swale length and slope.
Wet Ponds
The principle removal mechanisms are sedimentation of the particulate pollutants and biological
uptake of soluble nutrients (Dorman, 1989). Wet ponds are very effective in removing
pollutants if the detention time is long enough to allow the pollutants to settle out. Pollutant
removal rates have been found to be from low to high depending on the size of the basin relative
to its drainage area (Dorman, 1989).
Twenty-four sets of information on wet ponds' removal efficiencies were available in Schueler
et al, 1992. Current literature indicate that removal efficiency should increase with increased
treatment volume. However, plotting the treatment volume (inch per drainage acre) versus
removal efficiency did not show this for the ponds. This is probably due to many site specific
variables. Of the twenty-four, three had reported TSS removal efficiency of <32% while
twenty-one had TSS removal efficiency >54%. The three ponds with substantially lower
reported removal rates may be due to difference in calculation methods (pond #25) and the
storage volume being considerably less (ponds #9 and #10). Since these three ponds' removal
efficiencies were substantially different for most pollutants, they were discounted for determining
the probable removal rate of a properly designed and maintained wet pond. The probable
removal rates given in Table 5-2 show the range of the remaining efficiencies.
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Extended Detention Wet Ponds
The principal removal mechanisms are sedimentation of the particulate pollutants and biological
uptake of soluble nutrients. The upper stage of the extended detention wet pond should be
planted with marsh plants which increase the biological uptake.
Data on removal efficiencies for three extended detention wet ponds were available in Schueler
et al, 1992. Table 5-2 shows the range of efficiencies for TSS and TP from the raw data. As
expected, the TSS and TP removal efficiency for the extended wet pond were higher than for
the wet pond. However, there was not sufficient information on the remaining pollutants to
come to a similar conclusion. However, the extended detention wet pond probably provides
higher removal rates for all pollutants due to the increased detention time (which allows
additional settling) and the additional aquatic fringe (which provides increased biological uptake).
Extended Detention Dry Ponds
Seven sets of information on removal efficiencies for extended detention dry ponds were
available in Schueler et al, 1992. The removal efficiency of TSS fell into two distinct ranges.
Four ponds' removal efficiencies were from 3% to 30%, and three ponds' removal efficiencies
were from 70% to 87%. All of the ponds in the lower range had short detention times (under
10 hours). Settling column experiments have shown that most settling of suspended pollutants
occurs within the first 12 hours (OWML, 1983 cited in Schueler, 1987). Therefore extended
detention ponds should provide a minimum of 12 hours detention. Using this criteria, the 4
ponds with the low detention times were determined to have insufficient detention time and
therefore discounted for determining the probable range of effectiveness for properly designed
and maintained dry extended detention dry ponds. The removal efficiencies for the remaining
three ponds were used to determine the probable range of removal for extended detention dry
ponds.
Infiltration Basins
Pollutant removal for infiltration devices is achieved by capturing the stormwater runoff and
filtering it through the soils under the devices. The infiltration device effectively removes the
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soluble and fine particle pollutants in the captured water. The coarse grained pollutants should
be removed before entering the basin or trench proper to keep it from clogging. The removal
mechanisms of the water infiltrating into the soils involve sorption, precipitation, trapping,
straining and bacterial degradation and transformation. Actual removal rates in the soil will
depend on the solubility and chemistry of the pollutant (Schueler, 1987).
Because there were very little published data on effectiveness of infiltration basins or infiltration
trenches, the efficiencies shown as the probable range in Table 5-2 were calculated using a
method designed by Woodward-Clyde in 1986. The Woodward-Clyde report "Methodology for
Analysis of Detention Basins for Control of Urban Runoff Quality" (Woodward-Clyde, 1986)
produced a planning level estimate for performance of recharge devices based on percolating
area, treatment volume, soil percolation rate and regional rainfall. The report tested the
reliability of the results by comparing removal estimates for a range of conditions with those
produced by the model "STORM," and "SWMM."
In order to further test the methodology for this report, results were compared to data in the
NURP Final Report (EPA, 1983) for recharge basins in the Great Lake region. The results
were similar. In addition, the methodology results were compared to estimated removal rates
in Controlling Urban Runoff (Schueler, 1987) and they were consistent. Therefore, the
methodology appeared to provide reliable planning level removal rates.
Since there is essentially no difference in the procedure for analyzing infiltration basins and
infiltration trenches, they were analyzed together as recharge devices.
For recharge devices, the percent of pollutant removal is the same as the percent of runoff that
is captured by the device and infiltrates into the soil. Any runoff that percolates into the ground
and reaches surface waters through the groundwater is commonly assumed to have had the
pollutants removed by soil processes such as filtration and biological action and hence are
ignored by the analysis. Therefore, any runoff and pollutants that percolate into the ground are
assumed to be removed.
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Removal rates are dependent on an available storage volume. For the probable range of
effectiveness shown in Table 5-2, it was assumed that the design volume would equal 90% of
the average runoff volume.
Removal rates are also dependent on rainfall patterns that vary regionally. In order to account
for regional differences, the model was run for four different rainfall regions. Regional rainfall
data was obtained from "Analysis of Storm Event Characteristics for Selected Rainfall Gages
Throughout the United States" (Woodward-Clyde, 1989). The analysis was performed for four
CZMA regions including the region with the highest volume and intensity and lowest time
between storms (East Gulf), the lowest volume and intensity (Pacific Northwest), the highest
time between storms (Pacific South), and approximate average conditions (Mid-Atlantic).
Another important characteristic for removal efficiency is percolation rates. Only permeable
soils (SCS soil type A or B) should be used with infiltration devices. Since the removal
efficiency varies with percolation rate, the efficiency for "A" soils (minimum infiltration rate
2.41 in/hr to 8.27 in/hr) and "B" soils (minimum infiltration rate 0.52 in/hr to 1.02 in/hr)
(Schueler, 1987) are presented separately.
The efficiency is also based on the percolating area. Although as discussed above, the storage
volume was held constant at 90% of the average runoff volume, the percolating area could vary
based on the depth of the pond or trench. The tables assume the minimum depth of a basin is
2 feet and a trench is 3 feet. The maximum depth is 8 feet or the depth that can completely
drain within 72 hours.
To determine the maximum removal efficiencies for the two soil groups, the model was run
using the maximum percolation rate within the soil group and the maximum percolating area
(i.e. minimum depth). The minimum removal rate was based on the minimum percolation rate
and minimum percolating area (i.e. maximum depth).
For the infiltration basin the following was used:
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Minimum
Removal Rate
Maximum
Removal Rate
Soil A 2.4 in/hr perc, 8' height 8.3 in/hr perc, 2' height
Soil B 0.5 in/hr perc, 3' height 1.0 in/hr perc, 2' height
Since the infiltration trench is filed with stone, the available storage space typically equals 40%
the excavation volume (Schueler, 1987). Therefore, the effective height of an 8 foot trench is
8 feet x 40% = 3.2 feet. It is the available storage volume and effective height which are
important when determining the removal efficiency.
Therefore, for the infiltration trench the following was used:
Minimum Maximum
Removal Rate Removal Rate
Soil A 2.4 in/hr perc, 3.2' height 8.3 in/hr perc, 1.2' height
Soil B 0.5 in/hr perc, 3' height 1.0 in/hr perc, 1.2' height
Based on the runs for the four regions, the range of removal rates was estimated. It was
determined that the regional differences in removal rates were not large enough to justify
reporting removal rates regionally (see Appendix for model results).
Constructed Stormwater Wetlands
The pollutant removal performance of nearly twenty stormwater wetland systems were reported
in Woodward-Clyde, 1991. The probable range of removal effectiveness in Table 5-2 is for the
designs with a minimum area of wetlands equal to 1% of the drainage area. Although the
stormwater wetland systems monitored have differed greatly in their design and treatment
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volume, most have shown moderate to excellent pollutant removal capability under a range of
environmental conditions (Schueler et al, 1992).
Stormwater wetlands pollutant removal capability is comparable to that of wet ponds. Sediment
removal may be greater in well designed stormwater wetlands, but phosphorous removal is more
variable.
5.3.2 Roads Only
Infiltration Trenches
See infiltration basins in Section 5.3.1 for effectiveness information.
Porous Pavement
Two porous pavement studies were cited in the literature. They both obtained relatively high
pollutant removal rates. However, as previously stated, a Maryland study found that of 13
porous pavement sites that had been constructed 4 to 6 years earlier, only 2 facilities were
functioning as designed. Several of the sites evaluated failed due to clogging of the surface from
sediment during and following construction, as a result of sediment-laden runoff being conveyed
to the porous pavement surface.
Concrete Grid Pavement
The information on the removal efficiencies of concrete grid pavements is obtained from
laboratory studies by Day, et.al., 1981 and monitoring studies for a parking lot in downtown
Dayton, Ohio by Smith, et.al., 1981.
The laboratory studies by Day provide information on the runoff volume and pollutant load
reductions associated with concrete grid pavements. The monitoring studies by Smith provide
the removal efficiencies of concrete grid pavements as the reductions in pollutant concentration
and mass in water which has percolated through the concrete grid pavements. For the purpose
of this report, the pollutant removal efficiencies of the concrete grid pavement presented from
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both studies shall be interpreted as the reduction in runoff volume. Any runoff that percolates
into the ground and reaches surface waters through the groundwater is assumed to have had the
pollutants removed by soil processes such as filtration and biological action. Therefore, the
removal efficiencies of pollutant is assumed to be the reduction in runoff.
Concrete grid pavements are basically a form of infiltration measures. Therefore, as a
reference, their pollutant removal efficiencies should be similar to that of porous pavements.
Filtration Basin
Removal efficiencies for filtration basins were obtained primarily from two sources: laboratory
studies done in 1981 (Wanielista et al, 1981 cited in City of Austin, 1988) and monitoring
studies done on several filtration basins in Austin, Texas, 1990.
The Austin report contained the monitoring results for several basins. In addition, based on
these results the report estimated expected removal rates for several possible designs. Three of
the designs were chosen as appropriate for this category and are off-line sedimentation/filtration
basin, on-line sand/sod filtration basin, and on-line sand basin. The expected removal rates are
consistent with the monitoring study results and laboratory study. Therefore, the range of
probable removal rates given in Table 5-2 are the same as the expected removal rates presented
in the Austin Report, with two exceptions. The highest expected removal rate for TSS is 100%.
However, since during large storms some of the runoff will not be treated, 100% removal does
not seem realistic. Instead it was reduced to 90% for Table 5-2. In addition, the expected
removal rates do not include COD, so the COD removal rates reported from the monitoring
study were used.
Water Quality Inlet - Catch Basin
There are very little data available regarding the effectiveness of water quality inlets. The
configurations of outlet pipe and the permanent pool for sedimentation allow the catch basins to
function as small sediment basins with short detention time and high degree of turbulence.
Catch basins appear to trap only coarse-grained sediments.
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Water Quality Inlet - Catch Basin with Sand Filter
The effectiveness of catch basins with sand filter are estimated to be similar to filtration basins.
However, there are no available monitoring studies for catch basins with sand filters. The
effectiveness of the sediment chamber for removal of the different size particles depends on the
particle's setting velocity and the chamber's length and depth. The effectiveness of the filtration
media depends on the depth of the filter media.
Water Quality Inlet - Oil/Grit Separator
The pollutant removal of an oil/grit separator has not been widely tested in the field. Removal
efficiencies for oil/grit separator were obtained from two references. These references indicated
that oil/grit separators have marginal TSS removal efficiency, i.e., less than 25%. These
removal efficiencies are general estimates that inferred from studies on similar structures such
as catch basins. There were no specific oil and grease removal efficiencies provided for oil/grit
separators but oil and grease removal can be improved with the aid of adsorbent (Silverman et
al., 1988). One such application is to place the adsorbent in a removable fine mesh bag;
replacement of the adsorbent could be accomplished by replacing the exhausted bag with one
containing fresh adsorbent.
Porous pavement, concrete grid pavement, water quality inlets - catch basins, water quality inlets
- catch basins with sand filter, and water quality inlets - oil/grit separator are the post-
construction stormwater runoff treatments, which are effective for some urban roads and parking
lots but not highways.
5.4 COST
The cost of the management practices varies greatly and is dependent upon many factors such
as availability and proximity of materials, time of year and labor rates. The costs presented in
this document are a summary of costs found in published documents. These costs are presented
to give planners an idea of the cost of a practice relative to another but are not recommended
for use in estimating and bidding construction contracts. Local suppliers and contractors could
be contacted for this purpose. Cost data were generally influenced more by proximity to major
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urban centers rather than regionally. Consequently, regional variation of cost could not be
supported by the data obtained. It may be more effective to consider the cost ranges presented
as "national" averages and to adjust the cost on a regional basis using published regional cost
variation indexes (e.g., the regional cost index published by the Engineering News Record').
Quantitative cost data were presented in Table 5-3 of this report. Table 5-3 summarizes the total
annual cost, including the annualized construction cost. To annualize this cost, an interest rate
of 5% was assumed. The cost data used to develop these cost summaries are presented in
Appendix B.
The costs presented are only construction costs. They do not include the cost of such items as
land, engineering, and review fees.
The cost of the management practices are dependant on the treatment volume. Due to economy
of scale, as the treatment volume increases, the cost per cubic foot of water treated decreases.
Ponds tend to be the most economical practice for larger drainage areas. Infiltration trenches
and water quality inlets are typically only cost effective for relatively small drainage areas.
Vegetative controls are relatively inexpensive. In fact, grassed swales are less expensive to
construct than curb-and-gutter.
The following is a discussion of the factors that influence the costs that can be expected in
implementing various management practices.
5.4.1 Highways and Roads
Vegetative Filter Strip
The cost of VFS is dependent on the type of vegetation. If the natural vegetation is maintained,
the cost is minimal.
Generally an area that will serve as a VFS should not be cleared and graded, since it is more
effective if the natural vegetation is maintained. A VFS should only be seeded or sodded if the
area is disturbed for the associated development, otherwise it should remain undisturbed.
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Therefore the cost of VFS is assumed only to include the cost for sod or seed and any cost for
clearing and grading is a cost associated with site development and not installation of the
practice.
Grassed Swales
The cost of a grassed swale will vary depending upon the geometry of the swale (height and
width) and method of establishing the vegetation (seed or sod). The construction cost of grassed
swales are typically less than curb and gutter. However, the maintenance cost of swales is
generally higher than curb and gutter. Approximate costs are given in Table 5-3.
Wet Ponds
The cost of ponds is directly related to the storage volume. In addition, if the bedrock layer is
close to the surface the cost may increase exponentially.
The costs of wet ponds were obtained from four sources. The wide cost differences shown on
the wet pond cost chart is probably due to the less expensive ponds being constructed in natural
low lying areas where little or no excavation was required. However, these low lying areas are
often wetlands, and due to present-day strict wetlands laws, these low costs may not be realistic
in 1991.
Extended Detention Wet Ponds
The cost of an extended detention wet pond should be similar to the wet pond. The main cost
difference would be the outlet structure for the extended detention pond would need to be
designed to temporarily store the stormwater runoff.
There was no information available for extended detention wet pond costs, but in some cases the
cost difference between wet ponds and extended detention west ponds will be minimal.
Therefore, it was assumed that wet ponds and extended detention wet ponds have the same cost.
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Extended Detention Dry Pond
The cost of ponds is directly related to the storage volume. In addition, if the bedrock layer is
close to the surface, high excavation costs may make extended detention dry ponds impractical.
The cost of dry ponds were obtained from four sources and are shown in Table 5-3. In addition,
Chart 4, in Appendix C, shows the economy of scale for extended detention dry ponds.
Infiltration Basins
The cost of infiltration basins is directly related to the storage volume. Due to economy of
scale, as storage volume increases, cost per unit volume decreases. Infiltration basins are
typically cheaper per unit volume than extended detention dry ponds due to decreased cost of
the outlet structure. Infiltration basins are also cheaper on a per volume basis than infiltration
trenches.
Constructed Storm water Wetlands
Construction costs for stormwater wetlands have not been systematically analyzed, but are
expected to be marginally higher than wet ponds due to the more complex grading and wetland
planting costs (Schueler et al, 1992).
5.4.2 Roads Only
Infiltration Trenches
The cost of infiltration trenches is directly related to storage volume. As the storage volume
increases, cost per unit volume decreases. Schueler (1987) indicates that infiltration trenches
may not be economically practical on sites larger than 5 to 10 acres.
Porous Pavement
The cost of porous pavement should be measured as the incremental cost, or the cost beyond that
required for conventional asphalt pavement. However, to determine the full value of porous
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pavement one should also consider the savings from reducing land consumption and eliminating
storm systems, e.g. curbs, inlets and pipes (Cahill, 1991). Also, one must consider the
additional cost of directing pervious area runoff around porous pavement.
Concrete Grid Pavement
The cost per square foot of concrete grid pavements will vary depending on the types and
specifications of concrete grid pavements and the existing underlying soil conditions. Currently,
there are no ASTM standards specification governing properties of concrete grid pavement units.
However, the National Concrete Masonry Association (NCMA) has published an industry
standard specification for concrete grid pavers designated as A-15-82.
In addition to the initial installation cost involved, there will be maintenance costs such as grass
mowing, fertilizing and reseeding. The cost of concrete grid pavement is presented as the
incremental cost, i.e., cost beyond that required of conventional asphalt pavement. The
incremental cost of maintenance for concrete pavement shows a net decrease from that of asphalt
pavement. When comparing the maintenance cost between concrete grid and asphalt pavements,
concrete grid pavement does not require the minimum one overlay that is assumed necessary
during the 20 year lifespan of asphalt pavement.
The concrete grid pavements installed in place and annual maintenance cost presented in Table
5-3 are based on information provided by NCMA.
Filtration Basin
Data regarding the cost of filtration basins were obtained from engineers' estimates done in
Austin, Texas for various sized basins (Tull, 1990). These reported costs per cubic foot of
storage are higher than reported costs for infiltration devises, dry extended detention ponds or
wet ponds. No information was available regarding the maintenance costs of filtration basins.
However, because filtration basins function similar to infiltration basins, the annual operation
and maintenance cost was assumed to be the same percent of capital cost as infiltration basins.
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Water Quality Inlet - Catch Basin
In general, the cost of catch basins will be similar to those for standard precast inlets. The
annual maintenance cost of cleaning catch basins will depend on the number of times per year
they are cleaned and the method used. Cleaning catch basins manually by hand or with
clamshell buckets costs approximately twice as much as cleaning with a vacuum attachment to
a sweeper (SWRPC, 1991).
Water Quality Inlet - Catch Basin with Sand Filter
The cost of a catch basin with sand filter will depend on the size of the sedimentation and
filtration chambers, which depends on the drainage area. No information was available
regarding the maintenance cost of catch basins with sand filters. However, information was
available on the maintenance cost of oil/grit separators. It was estimated that the maintenance
cost of catch basins with sand filters would be higher than oil/grit separators since the sand filter
must be periodically replaced. Please note that although maintenance costs of catch basins were
available, they could not be used since they are reported in a different unit than catch basins with
sand filters (each verse drainage acre).
Water Quality Inlet - Oil/Grit Separator
The cost of the oil/grit separator will depend on the storage volume of the chambers which
depends on the drainage area and the configuration of the design components.
The annual cost of maintenance of oil/grit separators will depend on the number of times per
year they are cleaned and the method used. The maintenance costs were assumed to be the same
as cleaning catch basins.
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6.0
OPERATION AND MAINTENANCE
Operation and maintenance procedures that can be used to reduce or eliminate nonpoint source
pollution fall into four general categories: maintenance of vegetation, street cleaning, deicing
chemical use management, and containment bridge maintenance.
Maintenance of vegetation is important for keeping a vigorous vegetation which provides erosion
control and pollution reduction.
Street cleaning removes potential sources of storm water runoff pollution and therefore reduces
the pollutant loads in the runoff.
Deicing chemical use management reduces the amount of stormwater runoff pollution caused by
deicing chemicals. Sodium chloride, which is found in deicing salts, have high water solubility
and low relative affinity for absorption onto soils. Consequently, much of the salt washed from
salt piles or from applications to roads enters the groundwater or surface waters (Cheveron
Chemical Company, 1991). Studies have shown that vegetation can decrease salt concentrations
along roadways.
Containment during bridge maintenance is important to keep pollutants from falling directly into
surface waters during bridge maintenance.
Section 6.1 describes these management practices. Section 6.2 summarizes the effectiveness and
costs of the practices. Section 6.3 discusses the practices' effectiveness and basis for
determining the effectiveness. Section 6.4 discusses the practices' cost and the basis for
determining costs.
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6.1 DESCRIPTION
6.1.1 Maintenance of Vegetation
Establish and Maintain Vegetation
Maintaining a vigorous vegetation along road right-of-ways provides two water quality benefits.
Vegetation protects the area from erosion and it removes pollutants as discussed for vegetative
filter strips and grassed swales in Section 5.0. Grass is an effective type of vegetative ground
cover, however, it must be maintained.
Maintenance should include inspection and quick stabilization and reseeding of any eroding
areas. The number of grass mowings per growing season should be minimized to increase the
grass height and resistance to flow. However, the grass must be periodically mowed since at
some height and flow depth the grass will lay flat which reduces the pollutant reduction
capabilities. The optimum number of mowings should be determined locally based on plant
species and local conditions. In addition, the grass cuttings should be left on the ground to
reduce velocities and act as a mulch (Hartigan et al, 1989).
Sediments must also be removed from vegetative channels when the hydraulic capacity is no
longer available.
Pesticide/Herbicide Use Management
Limiting the application of pesticides and herbicides reduces the amount of these pollutants
entering the storm water runoff and, hence, coastal waters. The use of pesticides and herbicides
by State Highway Agencies (SHA) are typically managed through controls on application and
training. This has resulted in a low percent of total pollutant load being attributed to pesticides
and herbicides. Therefore, the pesticide/herbicide programs being used by SHAs should be
continued (Hartigan et al, 1989).
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6.1.2
Street Cleaning
Street Sweeping
Street cleaning uses either mechanical, vacuum or regenerative air sweepers. Most street
cleaning programs are designed to improve aesthetics. However, street cleaning programs can
also provide water quality befits by removing pollutants from the street surface before they are
washed into the storm sewer system or surface waters. Street cleaning is most effective at
removing debris and large particles. It is less effective at removing fine particles (SWRPC,
1991) and may even loosen fine particles embedded in the street surface and actually increase
the concentration of fine particles in the runoff water.
Street sweeping is not effective for highways, but may be effective for roads in urban areas.
Litter Control
Litter control programs and regulations are often established for their aesthetic and safety value.
However, these programs reduce nonpoint source pollution by removing potential pollutant
sources.
General Maintenance
General maintenance includes pot hole repairs and road-side repairs. Road repairs reduce
nonpoint source pollution by removing potential pollutant sources.
6.1.3 Deicing Chemical Use Management
Protection of Salt Piles
There are numerous environmental impacts associated with improper storage of salt piles. These
impacts include destroying vegetation, polluting groundwater, and increasing soil erosion.
According to the Salt Institute, almost all environmental problems associated with deicing salt
result from improper storage; therefore, salt piles should always be protected from the natural
elements - rain and snow. A Rhode Island DOT study estimated that 20% of the salt in
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unprotected piles was washed into the storm water runoff (The Land Management Project,
1989).
An under-roof storage facility is the best way to protect salt; however, there are a variety of
other building types available for salt storage. The main requirements needed for a successful
storage facility are: the salt piles should always be covered with a roof or temporary covering
material like tarpaulin, have an impervious surface for storage and handling areas, and provide
containment for contaminated runoff.
Minimization of the Application of Deicing Salts
States should follow EPA's guidelines for application rates to reduce the amounts of deicing salts
used. Some recommended guidelines are: apply salt in smaller increments based on changing
traffic and weather conditions, apply salt before storms that are expected to produce heavy
snowfalls, and coordinate the timing of plowing and chemical application, so the salt can break
the snow-ice bond at the road surface before the road is plowed. In addition, personnel training
and more accurate weather information can help minimize the use of deicing salts (Richardson,
1974).
Specially Equipped Salt Application Trucks
The trucks used to apply deicing salts can be equipped with ground-speed sensors which control
the salt discharge rate according to truck speed.
Use of Alternative Deicing Materials
Several deicing materials are available as an alternative to salt. These materials include calcium
magnesium acetate (CMA), calcium chloride (CaCl2), and urea. Of these materials, CMA is
generating the most attention because it may be environmentally safe. In addition, field tests
of CMA, by various state transportation agencies, show that CMA can deice roadways as well
as or better than road salt (Chevron Chemical Company, 1991). The major concern associated
with CMA is that it costs 20 times more than salt by weight. However, because CMA does not
contribute to corrosion of bridges and automobiles, its life-cycle cost may be less than salt.
Conversely, there are new technologies available for protecting new automobiles and bridges
from corrosion, so it is difficult to determine salt verses CMA's actual life-cycle cost.
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Therefore, CMA use should be evaluated on a site-by-site basis based on economic and
environmental impacts of road deicing. In environmentally sensitive areas, alternative deicers
like CMA may be the best economic and environmental choice. Table 6-1 summarizes some
advantages and disadvantages of using salt (NaCl), CMA, Ca Cl2, or urea.
Grassed Swales and Vegetative Filter Strips
Grassed swales and vegetative filter strips can reduce the concentration of salt in the runoff. See
Section 5.0 for information about these two management practices.
6.1.4 Containment During Bridge Maintenance
Contain Pollutants Generated During Bridge Maintenance
Pollutants generated during maintenance operations such as paint, rust and paint removal agents,
and sand blast material should be captured before it falls into coastal waters. Suspended tarps,
vacuums, or booms in water have been used to capture the waste materials.
6.2 SUMMARY TABLES
This section presents summary tables (Tables 6-2, and 6-3) for various management practices.
These summary tables are based on the detailed cost and effectiveness data presented in the
Appendix.
Table 6-2 summarizes the effectiveness and cost of the various operation and maintenance
management practices for maintenance of vegetation, street cleaning, and bridge maintenance.
Effectiveness was defined as the percent pollutant removal which the practice achieves if
properly designed, constructed and maintained. There are many pollutants found in urban runoff
and the effectiveness can be measured for each of the pollutants. Researchers have not come
to a consensus as to what pollutants are the best to use for measuring effectiveness. However
the pollutants that appear to be of most concern are Total Suspend Solids (TSS), Total
Phosphorus (TP), Total Nitrogen (TN), Chemical Oxygen Demand (COD), Lead (Pb), and Zinc
(Zn). Therefore, management practices' effectiveness for these pollutants are tabulated in Table
6-2.
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Table 6-1. Deicing Materials
ADVANTAGES
DISADVANTAGES
NaCl
• Works quickly when applied in
solution
• Least expensive material cost
• Very corrosive
• Harmful to roadside vegetation,
soils, and drinking water
CaCl2
• Works at low temperatures
• Works quickly (reaction with water
is exothermic)
• Very corrosive
• Harmful to roadside vegetation,
soils, and drinking water
Urea
• Works at low temperatures similar
to CaCI2
• Acts to clean oils off the roads
• Harmful to roadside vegetation
with frequent, heavy applications
• Expensive material cost
CMA
• Corrosion inhibitor
• Effectiveness similar to NaCl
indicated by extensive research
• Does not harm roadside vegetation
or drinking water
• Works in temperature range similar
to NaCl
• Expensive material cost
(Source: Nottingham et al, 1983)
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TABLE 6-2. OPERATION AND MAINTENANCE MANAGEMENT PRACTICES EFFECTIVENESS AND COST SUMMARY
MANAGEMENT PRACTICE
% REMOVAL
TSS
TP
TN
COD
Pb
Zn
COST
MAINTAIN VEGETATION
For Sediment Ave:
Control Reported Range:
Probable Range:
90
50-100
80-100
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Natural Succession Allowed To Occur -
Ave: $100/ac/Year
Reported Range: S50-S200/ac/Year
References: Schueler, 1987
For Pollutant Ave:
Removal Reported Range
Probable Range:
60
0-100
0-100
40
0-100
0-100
40
0-70
0-100
50
20-80
0-100
50
0-100
0-100
50
50-60
0-100
Natural Succession Not Allowed To Occur -
Ave: $800/ac/Year
Reported Range: $700-S900/ac/Year
References:
PESTICIDE/HERBICIDE USE
MANAGEMENT
Being Economically Used In Many States
Ave:
Reported Range:
Probable Range:
NA
NA
Being Effectively Used in Many States
STREET SWEEPING
Smooth Street, Ave:
Frequent Cleaning Reported Range:
(One or More Probable Range:
Passes Per Week)
20
20
20-50
NA
NA
NA
NA
5
0-10
0-10
25
5-35
20-50
NA
NA
10-30
Ave: S20/Curt> Mile
Reported Range: $10-J30/Curb Mile
References:
Infrequenl Cleaning Ave:
(One Pass Per Reported Range:
Month or Less) Probable Range:
NA
NA
0-20
NA
NA
NA
NA
NA
NA
5
0-10
0-20
NA
NA
0-10
LITTER CONTROL
Being Economically Used In Many Areas
Ave:
Reported Range:
Probable Range:
NA
NA
Being Effectively Used in Many Areas
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TABLE 6-2. OPERATION AND MAINTENANCE MANAGEMENT PRACTICES EFFECTIVENESS AND COST SUMMARY (Continued)
MANAGEMENT PRACTICE
% REMOVAL
TSS
TP
TN
COD
Pb
Zn
COST
GENERAL MAINTENANCE
Being Economically Used In Many Areas
Ave:
Reported Range:
Probable Range:
NA
NA
Being Effectively Used in Many Areas
CONTAIN POLLUTANTS GENERATED
DURING BRIDGE MAINTENANCE
Ave:
Reported Range:
Probable Range:
Varies With Method of Containment Used
NA
NA
50-100%*
•measured as reduction of all pollutants NA: Not Applicable
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-------
Table 6-3 summarizes the effectiveness and cost of deicing chemical use management practices.
This information is reported as percent of salt removal.
Pollutant removal is achieved through complex chemical, biological, and physical processes.
Due to the complexity of the processes and their dependence on a large variety of parameters,
researchers have not come to a consensus as to the effectiveness of the practices. Therefore,
Tables 6-2 and 6-3 present the effectiveness information and includes the average and range
observed in the reviewed literature, the probable range expected from a properly designed and
maintained practice (based on the literature and issues discussed in Section 6.3, and the
references considered in developing the data.
During the literature search for this project, it was apparent that there have been a limited
number of monitoring studies completed regarding the effectiveness of these management
practices. The results of the studies that were available are summarized in Tables 6-2 and 6-3.
However, performance monitoring studies are difficult to compare due to the differences in the
studies. The following variables are involved in BMP performance monitoring (Schueler, 1992):
• Number of storms monitored;
• Type and size of storm monitored;
• BMP design variations;
• Monitoring technique used;
• Pollutant removal calculation technique used;
• Seasons monitored; and
• Characteristics of contributing watershed.
It is also difficult to quantify the pollutant removal capabilities of a BMP because the
performance varies from storm to storm. The pollutant removal capabilities of a BMP will also
vary during the BMP's lifetime (Schueler, 1992).
Tables 6-2 and 6-3 present annual maintenance cost information. In these tables, the cost
information is annualized so that comparisons can be made from one practice to another. These
costs are presented to give planners an idea of the cost of practice relative to another and are
not recommended for use in estimating or bidding maintenance contracts.
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TABLE 6-3. OPERATION AND MAINTENANCE MANAGEMENT PRACTICES EFFECTIVENESS AND COST SUMMARY
% REMOVAL
MANAGEMENT PRACTICE
SALT (NaCI)
COST
PROTECTION OF SALT PILES
For Salt Storage Building-
Ave.:
Reported Range:
Probable Range:
NA
NA
90-100
Ave.: $30/ton salt
Reported Range: $10-70/ton salt
MINIMIZATION OF APPLICATION OF DEICING
SALTS
Being Economically Used in Many Areas
Ave.:
Reported Range:
Probable Range:
NA
NA
Deicing salts that are not applied to roads
will not enter runoff
SPECIALLY EQUIPPED SALT APPLICATION
TRUCKS
Ave.:
Reported Range:
Probable Range:
NA
NA
Deicing salts that are not applied to roads
will not enter runoff
For Spread Rate Control on Truck -
Ave.: $6,000/truck
Reported Range: $6,000/truck
USE OF ALTERNATIVE DEICING MATERIALS
CMA -
Ave.:
Reported Range:
Probable Range:
NA
NA
Deicing salts that are not applied to roads
will not enter runoff
Ave.: $650/ton
Reported Range: $650/ton
(Note: Cost of Salt $40/ton)
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6.3 EFFECTIVENESS
The following is a discussion of the factors that influence the effectiveness of the various
management practices shown in Tables 6-2 and 6-3. The data analyzed to draw the following
effectiveness conclusions are presented in Appendix A. See Section 6.2 for a discussion of the
effectiveness information.
6.3.1 Maintenance of Vegetation
Establish and Maintain Vegetation
Established vegetation is very effective in reducing erosion. Established vegetation can reduce
total suspended solid loads by 50-100% from pre-establishment loads (Woodward-Clyde, 1992).
Vegetation can also provide pollutant reduction as discussed for vegetative filter strips and
grassed swales in Section 5.0.
Pesticide/Herbicide Use Management
Existing pesticide/herbicide control programs implemented by State Highway Agencies (SHAs)
appear to be effective since the percent of total pollutant loads attributed to pesticides and
herbicides is low (Hartigan et al, 1989).
6.3.2 Street Cleaning
Street Sweeping
The effectiveness of street cleaning is dependant on many site specific variables including:
• rainfall patterns
• season
• pollutant accumulation
a. traffic density
b. dry deposition from local industrial and commercial activities
• equipment access (i.e., absence of parked vehicles)
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• frequency of cleaning
• operator proficiency
• equipment type and condition
Nine references contained information on the removal efficiency of street cleaning. However,
only four of these references reported the percent pollutant removal from street surface. These
rates will typically be higher than the percent pollutant removal from runoff because some of
the pollutant loads on the streets would never be taken-up by the runoff.
As part of NURP, 5 projects studied 10 sites. The conclusion from the NURP study was that
based on statistical testing, no significant reductions in EMC are realized by street sweeping
(EPA, 1983). However, a large database is required to actually identify possible effects. The
report concluded that if there are pollutant reductions from street cleaning, they are not large
(i.e., greater than 50%).
Street cleaning studies in Toronto, Castro Valley, CA and San Jose, CA indicate that street
cleaning on smooth streets done frequently can reduce total solids and heavy metal
concentrations in runoff. Only one study mentioned organics and nutrients and concluded that
street cleaning is not effective for these pollutants.
Litter Control
Litter control reduces nonpoint source pollution by removing potential pollutant sources.
General Maintenance
General maintenance also reduces nonpoint source pollution by removing potential pollutant
sources.
6.3.3 Deicing Chemical Use Management
Protection of Salt Piles
A properly designed, constructed and maintained salt storage facility should be able to eliminate
salt-laden runoff from leaving the site. EPA's salt and storage guidelines should be implemented
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to insure that the storage facility is structurally and environmentally safe. A Rhode Island DOT
study estimated that 20% of salt in unprotected piles was washed into storm water runoff. Some
of these guidelines are listed below:
• Storages should be large enough to hold the maximum amount of chemicals without
overflowing.
• Sufficient vertical and horizontal clearance should be provided so delivery trucks can
unload easily without damaging the structure.
• The storage should be sturdy enough to handle rough usage.
• Good lighting should be provided for night time operations.
Minimization of the Application of Deicing Salts, Specially Equipped Salt Application
Trucks, and Use of Alternative Deicing Materials
It is not possible to quantify the reduced pollutant loadings that will result from the use of these
management practices. However, if these management practices are implemented, less salt will
be applied to the roads, and therefore, less will enter coastal waters.
6.3.4 Containment During Bridge Maintenance
Contain Pollutants Generated During Bridge Maintenance
Although it is difficult to contain 100% of the pollutants, most pollutants should be contained
with suspended tarps, vacuums, or booms in the water.
6.4 COST
The cost of the management practices varies greatly and is dependent upon factors such as
availability and proximity of materials, time of year and labor rates. The costs presented in this
document are a summary of the costs found in published documents. These costs are presented
to give planners an idea of the cost of a practice relative to another but are not recommended
for use in estimating and bidding construction contracts. Local suppliers and contractors could
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be contacted for this purpose. Cost data were generally influenced more by proximity to major
urban centers rather than regionally. Consequently, regional variation of cost could not be
supported by the data obtained. It may be more effective to consider the cost ranges presented
as "national" averages and to adjust the cost on a regional basis using published regional cost
variation indexes (e.g., the regional cost index published by the Engineering News Record).
Quantitative cost data were presented in Tables 6-2 and 6-3 of this report. The following is a
discussion of the factors that influence the costs that can be expected in implementing various
management practices.
6.4.1 Maintenance of Vegetation
Establish and Maintain Vegetation
The cost to maintain vegetation will partially depend on if natural succession is allowed to occur.
Pesticide/Herbicide Use Management
Many State Highway Agencies have effective pesticide/herbicide programs in place.
6.4.2 Street Cleaning
Street Cleaning
One source was obtained that included the operating cost per curb-mile for 5 sites. These costs
included labor, equipment depreciation, fuel, maintenance/materials, overhead and disposal.
Litter Control
Many areas have effective litter control programs in place such as the Adopt-A-Highway
Program.
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General Maintenance
No costs were found in the literature.
6.4.3 Deicing Chemical Use Management
Protection of Salt Piles
One reference was found that gave the construction cost of 17 different constructed salt storage
buildings.
Minimization of Application of Deicing Salts
No costs were found in the literature, however, the average cost/ton of salt is $25 to $50. Thus,
reducing the amount applied would result in a savings of $1.25 to $2.50 per 100 pounds.
Specially Equipped Application Trucks
One reference was found for this cost. This cost includes equipment only and not calibration
or maintenance costs.
Use of Alternative Deicing Materials
Two references were found which gave the cost of alternative deicing materials. In addition,
two references compared the economic cost of road salt and corrosion caused by salt, versus the
economic cost of deicing salt alternatives, which were not as harmful to the environment,
infrastructure, and automobiles (Foster, 1990 and Chevron, 1991).
6.4.4 Containment During Bridge Maintenance
Contain Pollutants Generated During Bridge Maintenance
Although the cost of containing pollutants during bridge maintenance will depend upon the
containment method used, one reference estimated the cost of containing paint chips with a
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tarpaulin and then disposing the paint chips in a properly designed landfill to be approximately
$7,000 (Heller et al, 1992).
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7.0
MANAGEMENT PRACTICE OPTIONS
The following section presents management practice options for Roads, Highways and Bridges.
The management practices listed are mainly for illustrative purposes and they are not all-
inclusive. State or local laws, rules, or standards may also require the use of additional
practices from those listed in this section.
7.1 PLANNING AND DESIGN PRACTICES FOR ROADS AND HIGHWAYS
In the initial planning and design phase, roads and highways should be located away from coastal
shorelines, critical habitat, wetlands, riparian areas, drainage channels and streams. Potential
erosion, sedimentation, and pollution problems should be considered. These practices can be
used for all new roads and highways, including residential streets.
The best time to address control of NPS runoff pollution from roads and highways is during the
planning process. Locating roads and highways away from critical areas, and receiving waters
is the most suitable means for controlling runoff pollution from reaching the receiving waters.
However, when roads and highways must be located near receiving waters, then effective
controls should be considered to treat the runoff as necessary to mitigate any potential NPS
pollution.
The AASHTO Highway Subcommittee on Design guidance presented in "A Guide for
Transportation Landscape and Environmental Design" (AASHTO, 1991) stresses careful project
planning early in the design process that can often prevent the displacement of sensitive land or
water areas. In addition, the FHWA's Federal-Aid Policy Guide (FHWA, 1991) indicates that
it is the policy of the FHWA that Federal-aid highways and highways constructed under the
direct supervision of FHWA shall be located, designed, constructed and operated according to
standards that will minimize erosion and sediment damage to the highway and adjacent properties
and abate pollution of surface and ground water resources.
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Practices
The following practices listed below can be used. Descriptions of some of these practices can
be found in Section 3.0 of this document. Descriptions of the structural practices can be found
in Section 5.0 of this document.
• Provide design details for permanent erosion and sediment controls (e.g.
vegetative buffer strips, grassed swales, pond systems, infiltration systems,
constructed stormwater wetlands, and energy dissipators and velocity controls)
during the planning phase of roads, highways and bridges. (See American
Association of State Highway Transportation Officials (AASHTO), 1991(a); and
Hartigan et. al., 1989)
• Avoid marshes, bogs, and other low lying lands subject to flooding. All wetlands
that are within the highway corridor and subject to removal should be mitigated.
(See AASHTO, 1991(b); and Campbell, 1988)
• Avoid locations requiring excessive cut and fill. (See AASHTO, 1991(b) and
Campbell, 1988)
• Avoid placing highways at right angles to a series of natural drainage channels.
See AASHTO, 1991(b))
• Avoid locations subject to subsidence, sink holes, landslides, rock outcroppings,
and highly erodible soils. (See AASHTO, 1991(b); and Campbell, 1988)
• Select locations on high ground.
• Size rights-of-way to include space for siting runoff pollution control structures
as appropriate. (See Hartigan et. al, 1989; and AASHTO, 1991(a))
• Design residential roads and streets in accordance with local subdivision
regulations, zoning ordinances, and other local site planning requirements.
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• Select the most economic and environmentally sound route location. (See
AASHTO, 1991(b) and Campbell, 1989)
• Use interactive computer models to determine stormwater runoff impacts with all
proposed route corridors. (See Driscoll et. al., 1990)
• Prepare an environmental impact assessment. (See AASHTO, 1991(b))
• Coordinate the design of pollution controls with appropriate State and Federal
environmental agencies.
• Prepare official mapping to show location of proposed highway corridors.
Effectiveness and Cost
The most economical time to consider erosion/sediment and runoff pollution control is during
the planning and design phase of roads and highways. It is much more costly to correct NPS
pollution problems after a road or highway has already been built. The most effective and often
economical control is to locate the roads as far away from receiving waters and critical areas as
possible. However, some portions of roads and highways cannot be located where NPS
pollution does not pose a threat to receiving waters. In these cases, interactive computer models
designed to run on a PC (e.g. FHWA's model (Driscoll et al., 1990)) can be used to examine
the impacts of the proposed road or highway on receiving waters. If controls are needed, then
several economical and effective practices (e.g. vegetated buffer strips, grassed swales, pond
systems, etc.) can be considered and used to treat runoff. Effectiveness and cost information
for these practices are presented in Section 5.0.
7.2 PLANNING AND DESIGN PRACTICES FOR BRIDGES
New bridge structures should be sited and designed in such a manner that shellfish beds,
fisheries, wetlands, critical habitat areas, and other sensitive ecosystems are protected. Bridge
waterway crossings are preferred to causeway designs. These practices can be used for new
bridge structures that cannot avoid locations in areas with identified sensitive ecosystems such
as oyster beds, clam harvest areas, specialized fisheries, and critical flora/fauna habitats. It
should be noted that some bridges may also be subject to U.S. Coast Guard approval by
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Nationwide Permit No. 15, issued by the U.S. Army Corps of Engineers (USACE) under
Section 404 of the Clean Water Act.
Research has shown that bridge construction in coastal areas may cause significant erosion and
sedimentation resulting in the loss of wetlands and riparian vegetation and runoff from bridges
may deliver considerable loadings of heavy metals, hydrocarbons, toxic substances and deicing
materials to receiving waters, as a result of direct delivery through scupper drains with no
overland buffering (Irwin and Losey, 1978; and McKenzie and Irwin, 1983). Bridge
maintenance can also contribute heavy loads of lead, rust, paint, particulates, solvents, and
cleaners. States such as South Carolina and Florida have been actively working to mitigate the
pollution effects from bridge runoff. Guidelines have also been prepared for the management
of runoff from bridges (Wanielista et. al, 1980).
Practices
The practices listed below can be used. Descriptions of some of these practices can be found
in AASHTO, 1989; U.S. Coast Guard, 1983; and Section 3.0 of this document.
• Coordinate design with FHWA, USCG, USACE, and other State and Federal
agencies as appropriate.
• Review environmental impact assessment to insure environmental concerns are
met.
• Avoid locations requiring numerous river crossings.
• Direct pollutant loadings away from bridge decks by diverting runoff waters to
land for treatment.
• Avoid the use of scupper drains on bridges crossing sensitive ecosystems.
• Locate bridges to avoid sensitive ecosystems.
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Effectiveness and Cost
The costs of implementing the above practices must be weighted against the economic benefits
of protecting commercial fisheries and shellfish harvesting areas from runoff waters potentially
containing road surface containments including deicing salts and abrasives, heavy metals,
accidental toxic spills, and automotive fluid leakage. To protect these sensitive areas,
management practices such as minimizing the use of scupper drains and diverting runoff waters
to land for treatment in detention ponds and infiltration systems should be used to mitigate the
pollutant loadings. See Section 5.0 for costs and effectiveness data of ponds, wetlands, and
filtration devices.
7.3 CONSTRUCTION PROJECT PRACTICES
Practices should be used at all road, highway, and bridge construction projects in order to
minimize the detachment and mobilization of sediment, and control/retain sediment onsite.
Erosion and sedimentation from road, highway, and bridge construction, as well as unstabilized
cut and fill areas, can result in serious environmental impacts on receiving waters. Additionally,
FHWA's Federal Aid Policy Guide (FHWA, 1991) also requires that erosion and sediment
damage from the construction of Federal-aid highways and highways under the direct supervision
of FHWA be minimized.
Practices
The practices listed below can be used. Guidance on these and other erosion and sediment
control practices for road and highway projects can also be found in AASHTO, 1990; FHWA,
1985; and in Section 4.0 of this document.
• Write erosion and sediment control requirements into plans, specifications, and
estimates for Federal aid construction contracts, for highways and bridges
(FHWA, 1991).
• Coordinate erosion and sediment controls with FHWA and AASHTO guidelines.
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• Install permanent erosion and sediment control structures at the earliest
practicable time in the construction phase.
• After construction, temporary control structures are to be removed and areas
restored. Sediments will be disposed of in accordance with State and Federal
regulations.
• Coordinate temporary erosion and sediment control structures with permanent
practices.
Effectiveness and Cost
Detailed information on the effectiveness and cost of erosion and sediment control management
practices can be found in Urban BMP Cost and Effectiveness Summary Data for 6217(g>)
Guidance - Erosion and Sediment Control During Construction (Woodward-Clyde, 1993).
7.4 CONSTRUCTION SITE CHEMICAL CONTROL PRACTICES
Practices should be used at all roads, hoghway, and bridge construction projects in order to
minimize toxic and nutrient loadings by reducing the generation and migration of toxic
substances and avoiding excess application of nutrients.
Toxic substances and nutrients tend to bind to fine soil particles, and control of sediments in
most cases, can limit the loadings of these pollutants. However, some substances and nutrients
(e.g. nitrogen) are very soluble, and excess applications or spills during construction can pose
significant environmental impacts.
Practices
The practices listed below can be used.
• Limit machinery maintenance to areas designated and equipped for this activity.
• Limit machinery site access and establish machinery staging pads.
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• Require proper handling and storage of fuels, oils, fertilizers, and other potential
NPS pollutants.
• Minimize runoff entering and leaving the site through perimeter and onsite
sediment controls.
• Inspect and maintain erosion and sediment control practices (both onsite and
perimeter) until disturbed areas are permanently stabilized.
• Divert and convey offsite runoff around disturbed soils and steep slopes to stable
areas in order to prevent transport of pollutants offsite.
• Locate large graded areas on the most level portion of the site and avoid the
development of steep vegetated slopes.
Effectiveness and Cost
Detailed information on the effectiveness and cost of erosion and sediment control management
practices can be found in Urban BMP Cost and Effectiveness Summary Data for 6217(g)
Guidance - Erosion and Sediment Control During Construction (Woodward-Clyde, 1993).
7.5 OPERATION AND MAINTENANCE PREVENTIVE PRACTICES
Effective operation and maintenance programs can reduce NPS pollution from erosion of poorly
vegetated areas; pesticides and nutrients; litter and debris; deicing materials; and debris and toxic
substances from bridge maintenance. The U.S. Coast Guard and states such as Virginia require
that loadings of paint chips, solvents, and particulates be controlled during bridge maintenance.
Additionally, EPA, FHWA, and the Salt Institute encourage the minimization of the application
of road salts.
Practices
The practices listed below can be used for effective operation and maintenance of roads.
Descriptions of some of these practices can be found in Section 6.0 of this document.
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• Establish pesticide/herbicide use and nutrient management programs. (See
Hartigan et al, 1989)
• Restrict herbicide and pesticide use in highway rights-of-way to applicators
certified under FIFRA to assure safe and effective application.
• The use of chemicals such as soil stabilizers, dust palliatives, sterilants, and
growth inhibitors should be limited to the best estimate of optimum application
rates. All feasible measures should be taken to avoid excess application and
consequent intrusion of such chemicals into surface runoff. (See Hartigan et al,
1989; FHWA, 1991)
• Sweep, vacuum, and wash residential/urban streets and parking lots. (See Pitt,
1986; EPA, 1982; Puget Sound Water Quality Authority, 1989; and City of
Austin, 1988)
• Collect and remove road debris.
• Cover salt storage piles. (See Salt Institute, 1987)
• Minimize and regulate the application of deicing salts. (See Salt Institute, 1991)
• Use specially equipped salt application trucks. (See Salt Institute, 1991)
• Use alternative deicing materials, besides salt, where feasible. (See
Transportation Research Board, 1991)
• Organize education programs.
• Encourage litter and debris control management.
• Provide general maintenance such as pothole repair and sealing cracks.
• Inspect and maintain stormwater management and pollution control facilities. (See
Yousef, et al, 1991)
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• Accumulated sediment from stormwater management and pollution control
facilities, and any wastes generated during maintenance, should be disposed of in
accordance with appropriate local, State, and Federal regulations. (See Yousef
et al, 1991)
• Reduce the delivery of pollutants used or generated during bridge maintenance
(e.g., paint, solvents, scrapings) from entering receiving waters (e.g., suspended
tarps, vacuums, or booms). (See AASHTO, 1987)
Effectiveness and Cost
Preventive maintenance is a time-proven cost-effective management approach. Regularly
scheduled maintenance to repair potholes, restore vegetation, and frequent sweeping and
vacuuming of urban streets have effective results in pollution control. Litter control and clean-
up practices are a low cost means for eliminating causes of pollution as are the proper handling
of fertilizers, pesticides, and other toxic materials including deicing salts and abrasives. Tables
6-2 and 6-3 present summary information on the cost and effectiveness of operation and
maintenance practices for roads, highways, and bridges. Many states and communities are
already implementing several of these practices within their budget. As seen in Table 6-3, the
use of road salt alternatives such as CMA can be very costly. However, some researchers have
indicated that reductions in corrosion of infrastructure, damage to roadside vegetation, and the
quantity of material that needs to be applied may offset the higher cost of CMA. Use of road
salt minimization practices such as salt storage protection and special salt spreading equipment
reduces the amount of salt that a state or community must purchase. Consequently,
implementation of these practices can pay for themselves through savings in salt purchasing
costs. Similar programs such as nutrient and pesticide management can also lead to decreased
expenditures for materials. Detailed cost and effectiveness data for these practices are presented
in Section 6.0.
7.6 OPERATION AND MAINTENANCE VEGETATIVE PRACTICES
Vegetated areas and stormwater management systems along roads, highways and bridges should
be maintained, and cut and fill areas should be stabilized. Substantial amounts of eroded
material can be generated from poorly vegetated areas and unstable cut and fill areas. The
Federal-Aid Policy Guide (FHWA, 1991) that indicates erosion control measures should be
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emphasized by the maintenance departments and the AASHTO "Model Drainage Manual"
(AASHTO, 1991) that indicates a thorough maintenance and follow-up program should be
implemented.
Practices
The practices listed below can be used.
• Seed and fertilize; seed and mulch; and/or sod damaged vegetated areas and
slopes.
• Construct retaining walls.
• Develop an inspection program to ensure all areas are stabilized.
• Use energy dissipators and velocity controls to reduce runoff velocity and
erosion.
• Reduce steepness of side slopes.
Effectiveness and Cost
The costs associated with erosion and sediment loss are significant. The practices listed for the
maintenance of roads, highways, and bridges are effective preventive approaches to erosion and
sediment control. See Sections 4.0 and 6.0 for information on cost and effectiveness.
7.7 RETROFIT PRACTICES
Retrofitting control structures within rights-of-way or adjacent land areas can reduce pollutant
loadings from existing roads, highways and bridges. Older and poorly located roads, highways
and bridges may be generating significant NPS pollution loads that could severely impact
receiving waters and their tributaries. Studies by many agencies and states such as FHWA
(Driscoll et al, 1989 and 1990; and Gupta, 1981), EPA (Pitt and Amy, 1973; and Sartor and
Boyd, 1972), the State of Washington (Portele et al, 1982) and Pennsylvania (Spotts, 1989) have
quantified these loads as well as their impacts.
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Practices
The practices listed below can be used. Descriptions of structural stormwater management and
pollution control facilities can be found in Section 5.0 of this document.
• Locate runoff treatment facilities within existing rights-of-way or in medians and
interchange loops.
• Develop multiple use treatment facilities on adjacent lands (e.g. parks and golf
courses).
• Acquire additional land for locating treatment facilities.
• Use underground storage.
Effectiveness and Cost
Cost and effectiveness data for structural stormwater management and pollution control facilities
are presented in Section 5.0. Installing these facilities on existing roads, highways and bridges
can be more costly because of the need to purchase additional land. However, multiple-use
facilities on adjacent lands can offset this cost. As with other sections of this document, the
costs of loss of habitat, fisheries, and recreational areas must be weighed against the cost of
retrofitting existing roads, highways and bridges to control NPS pollutant loads.
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8.0
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APPENDICES
-------
APPENDIX A
EFFICIENCY DATA
-------
MANAGEMENT PRACTICE'S REMOVAL EFFICIENCY DATA
MANAGEMENT PRACTICE FOR URBAN STORMWATER RUNOFF
Infiltration Basin
Infiltration Trench
Vegetative Filter Strip (VFS)
Grassed Swale
Porous Pavement
Concrete Grid Pavement
Filtration Basins
Water Quality Inlet - Catch Basin
Water Quality Inlet - Catch Basin with Sand Filter
Water Quality Inlet - Oil/Grit Separators
Dry. Extended Detention Ponds*
Wet Ponds*
Wet Extended Detention Ponds*
Stormwater Wetlands*
Extended Detention Wetlands*
Natural Wetlands*
Pond/Wetland Systems*
Wetlands
~Compiled by Metropolitan Washington Council of Governments
80040000H:\wp\Report\Roads\append-a.tbl
A-l
Woodward-Clyde
January 29, 1993
-------
Mangement Practice: INFILTRATION BASIN
DESCRIP-
TION
LOCA-
TION
WATERSHED
AREA
(acres)
TREATMENT
VOL.
INFIL-
TRATION
RATE
fin./hour)
REMOVAL EFFICIENCY (%)
STUDY TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Infiltration
Basin
DC
5 ac. minimum,
20 ac.
maximum
Complete 2 yr
runoff volume
0.27
minimum
99
65-75
60-70
BAC: 98
BOD: 90
TM: 95-99
From field
testing of
similar rapid
infiltration land
treatment
systems
NVPDC, 1979
and EPA, 1977
cited in
Schueler, 1987
Infiltration
Basin
DC
5 ac. minimum,
50 ac.
maximum
runoff from 1
in. storm
0.27
minimum
90
60-70
55-60
BAC: 90
BOD: 80
TM: 85-90
From modeling
studies and
field studies
NVPDC, 1979
and Griffin, et
al, 1980 cited
in Schueler,
1987
Infiltration
Basin
DC
5 ac. minimum,
50 ac.
maximum
0.5 in. runoff
/impervious
acre
0.27
minimum
75
50-55
45-50
BAC: 75
BOD: 70
TM: 75-80
From modeling
studies and
field studies
NVPDC, 1979
and Griffin, et '
al, 1980 cited
in Schueler,
1987
Recharge
Device
Great
Lakes
Efficiency
independent of
watershed area
109 cf./ac.
6.0
45
45
45
45
45
45
45
45
Read from
chart
developed from
NURP data
analysis
EPA, 1983
Recharge
Device
DC
Efficiency
independent of
watershed area
Runoff from 1
in. storm
0.5 to 8.27
00
75-98
75-98
75-98
75-98
75-98
75-98
75-98
From model
Woodward-
Clyde, 1986
Recharge
Device
DC
Efficiency
independent of
watershed area
0.5 in.
runoff/imper.
acre
0.5 to 8.27
55-
90
55-90
55-90
55-90
55-90
55-90
55-90
55-90
From model
Woodward-
Clyde, 1986
Recharge
Device
Great
Lakes
Efficiency
independent of
watershed area
109 ef./ac.
6.0
50
50
50
50
50
50
50
50
From model
Woodward-
Clyde, 1986
80040000H:\wp\Report\Roads\append-a.tbl
A-2
Woodward-Clyde
January 29, 1993
-------
Management Practice: INFILTRATION TRENCH
DESCRIP-
TION
LOCA-
TION
WATER-
SHED
AREA
(Acres)
TREAT-
MENT
VOL.
INFIL-
TRATION
RATE
(In./Hour)
REMOVAL EFFICIENCY (%)
STUDY TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Infiltration
trench
DC
5 ac max
Complete
storm
volume
0.27
minimum
99
65-75
60-70
BAC: 98
BOD: 90
TM: 95-99
From field
testing of
similar rapid
infiltration
land treatment
systems
NVPDC, 1979 and
EPA, 1977 cited in
Schueler, 1987
Infiltration
trench
DC
5 ac max
runoff
from 1 in.
storm
0.27
minimum
90
60-70
55-60
BAC: 90
BOD: 80
TM: 85-90
From modeling
studies and field
studies
NVPDC, 1979 and
Griffin, el al, 1980
cited in Schueler,
1987
Infiltration
trench
DC
5 ac max
0.5 in.
runoff
impervious
acre
0.27 min
75
50-55
45-55
BAC: 75
BOD: 70
TM: 75-80
From modeling
studies and field
studies
NVPDC, 1979 and
Griffin, et al, 1980
cited in Schueler,
1987
Infiltration
trench
NA
NA
NA
NA
96
41
61
BOD: 84
NA
Biggers, et al,
1980 and USEPA,
1983 cited in Kuo,
et al, 1988
Infiltration
trench
NA
NA
NA
NA
50
60
(-8)
NA
NURP, 1983 cited
in Lugbill, 1990
Recharge
Device
Great
Lakes
Efficiency
independent
of
watershed
area
109 cf./ac.
6.0
45
45
45
45
45
45
45
45
Read from chart
developed from
NURP data
analysis
EPA, 1983
Recharge
Device
DC
Efficiency
independent
of
watershed
area
Runoff
from 1 in.
storm
0.5 to 8.27
75-98
75-98
75-98
75-98
75-98
75-98
75-98
75-98
From model
Woodward-Clyde,
1986
80040000H:\wp\Rq>orl\Road$\appcnd-a.lbl
A-3
Woodward-Clyde
January 29, 1993
-------
Management Practice: INFILTRATION TRENCH
DESCRIP-
TION
LOCA-
TION
WATER-
SHED
AREA
(Acres)
TREAT-
MENT
VOL.
INFIL-
TRATION
RATE
(In./Hour)
REMOVAL EFFICIENCY (%)
STUDY TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Recharge
Device
DC
Efficiency
independent
of
watershed
area
0.5 in.
runoff/imp
er.
acre
0.5 to 8.27
55-90
55-90
55-90
55-90
55-90
55-90
55-90
55-90
From model
Woodward-Clyde,
1986
Recharge
Device
Great
Lakes
Efficiency
independent
of
watershed
area
109 cf./ac.
6.0
50
50
50
50
50
50
50
50
From model
Woodward-Clyde,
1986
8(XM0000H:\wp\Report\Roads\append-a.tbl
A-4
Woodward-Clyde
January 29, 1993
-------
Management Practice: VEGETATIVE FILTER STRIP (VFS)
DESCRIPTION
LOCA-
TION
WATER-
SHED
AREA (ac)
VFS
SLOPE
VFS
LENGTH
POLLUTANT REMOVAL EFFICIENCY (%)
STUDY
TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Vegetative buffer
RI
NA
NA
NA
Sec Chart
Based on
multiple
simulations
of pollutant
(TSS)
generation,
transport Sl
removal for
buffer strips
under various
site
conditions
using the P8
urban
catchment
model.
IEP, 1991
Vegetative filter
NA
2.5%
85'
Dropped
from 80% to
5056 in 1
season
Varied from
20-80%
Ave= 53%
16 month
study for
sediment
control
Hayes &
Hairston, 1983
cited in
Casman, 1990
\
Orchard grass
buffer
Virginia
NA
NA
31'
70-98
65-95
(-192)-70
66
Monitored
test plots, no
information
on pollution
source
Dillaha, et al,
1989 cited in
Click, et al,
1991
Bluegrass sod
buffer
NA
NA
4'
78
Pollutant
source - up
slope bare
soil
Neibling and
Alberts, 1979
cited in Glick,
et al, 1991
80(W0000H:\wp\Report\Road3\append-a.tbl
A-5
Woodward-Clyde
January 29, 1993
-------
Management Practice: VEGETATIVE FILTER STRIP (VFS)
DESCRIPTION
LOCA-
TION
WATER-
SHED
AREA (ac)
VFS
SLOPE
VFS
LENGTH
POLLUTANT REMOVAL EFFICIENCY (%)
STUDY
TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Grass level
spreader
Virginia
NA
NA
70'
70
(Increasing
length from
70' to 150'
increased
removal rates
only
minutely)
28
20
51
NN:11
Monitored
March to
June '87 - 8
storms,
Pantops
Shopping
Center,
Charlottesvill
e, VA
VA Dept. of
Cons., 1987
Filter strip-
properly designed
and operated
Minn.
NA
NA
NA
30-50
Nonpoint
Source Control
Task Force,
1983 cited in
Minnesota
PCA, 1989 ,
Turf strip
D.C.
NA
NA
20'
20-40
0-20
0-20
0-20
TM: 20-40
Schueler, 1987
Forested strip
with level
spreader
D.C.
NA
NA
100'
80-100
40-60
40-60
60-80
TM: 80-
100
Schueler, 1987
VFS- Source
parking lot
NA
NA
NA
BulTer not effective in reducing pollutant.
Preliminary study, final conclusions not yet reached, but prelim indicates buffer not effective for urban runoff.
Possible reasons, 1) conc. in utban runoff significantly lower than agricult. or forest 2) urban runoff has excess
transport capacity when entering buffer and detaches sediment and adsorbed pollutants with no deposition
occurring.
Glick, et al,
1991
Vegetative
Control
NA
NA
NA
See Chart
90% of
TSS
removal
50 % of
TSS
removal
CU:60%
of TSS
removal
Generated
from
research, see
grass swales
along
highways
table
Hartigan,
et.al., 1989
Agriculture VFS
NA
NA
NA
o Effectiveness
as it is being bu
o VFS more efl
o Effectiveness
of VFS de
ried.
ective in r
of VFS hi
creases with ti
emoving SS th
;hly dependent
me as sediment
in nutrients
on condition o
accuniuli
f filter
ites within
it unless the v
egetation can
grow as fast
Casman, 1990
80040000H:\wp\Rcpon\Roada\appcnd-a.tbl
A-6
Woodward-Clyde
January 29, 1993
-------
Management Practice: VEGETATIVE FILTER STRIP (VPS)
DESCRIPTION
LOCA-
WATER-
VFS
VFS
POLLUTANT REMOVAL EFFICIENCY (%)
STUDY
REFERENCE
TION
SHED
AREA (ac)
SLOPE
LENGTH
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
TYPE
Agriculture
vegetated filter.
D.C.
NA
11%
30'
95
80
70
4
NH4: 69
TKN: 80
P04: 30
Runoff from
Agriculture
feed lot,
storm
Dillah et al,
1988 cited in
Caiman, 1990
NA
11%
15'
87
63
61
-36
NH4: 34
TKN: 64
PD4: -20
simulated- 2
year in
Potomac
Region. Did
not capture
NA
16%
30'
88
57
71
17
NH4: -35
TKN: 72
PCM: -51
change in
filter
efficiency
over period
of time. 2
NA
16%
15'
76
52
67
3
NH4: -21
TKN: 69
P04: -108
test runs
separated by
7 days
Agriculture, VFS
on sandy loam
MD
NA
3%
30'
82
42
Runoff:
41
Leachate:
87
Total: 83
Agriculture
study, 3
simulated
storms over 3
weeks during
Magette, 1987
cited in
Casman, 1990
NA
4%
30'
82
25
Runoff:
48
growing
season.
Subsurface
NA
5%
30'
86
52
Runoff:
51
Leachate:
3
Total: 11
leaching loss
important
component of
inorganic N
movement
from
'na
3%
15'
65
22
Runoff:
-15
Leachate:-
10
Total:-20
agricultural
areas
NA
4%
15'
66
27
Runoff:-6
80040000H:\wp\Report\Roads\appecd-a.tbl
A-7
Woodward-Clyde
January 29, 1993
-------
Management Practice: VEGETATIVE FILTER STRIP (VFS)
DESCRIPTION
LOCA-
WATER-
VFS
VFS
POLLUTANT REMOVAL EFFICIENCY (%)
STUDY
REFERENCE
TION
SHED
AREA (ac)
SLOPE
LENGTH
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
TYPE
NA
5%
15'
72
41
Runoff:
-17
Lcachate:
39
Total:36
Agriculture,
mixture rye,
fescues and
bluegrass on loam
soil:
Surface Runoff
Only:
Surface and
Groundwater:
NA
2%
2%
wr> in
00 00
99
95
94
84
OP:98
TKN: 99
NH4: 88
OP:92
TKN: 92
NH4:78
Measured
surface and
subsurface
leaving site
over 2 years.
Parlor waste
discharged 2
times a day.
Scbwer &
Clausen, 1989
cited in
Casman, 1990
Snow-melt
35
TKN: 57
Seasonal
Efficiency
Winter
95
TKN: 94
Growing
96
TKN: 98
Spring/Fall
96
TKN: 94
o As loading rates increase, efficiency decreases
80040000H:\wp\Repoit\Roads\append-a.tbl
A-8
Woodward-Clyde
January 29, 1993
-------
Management Practice: GRASSED SWALE
DESCRIPTION
LOCATION
1
SLOPE
LENGTH
(FT)
REMOVAL EFFICIENCY (%)
STUDY TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Low vegetation density &
height
DC
2-6%
NA
No significant water quality benefit measured, but report concluded that if residence time and
infiltration capability increased, then could be effective BMP
Study 3 swales, NURP
at Wash. DC suburbs
Schueler, 1987;
British Columbia
Res. Corp., 1991;
and EPA, 1983
Grassed swale with no check
dams
DC
high
NA
0-20
0-20
0-20
TM: 0-20
OD: 0-20
Schueler, 1987
Graised swale with check
dams
DC
low
NA
20-40
20-40
20-40
TM: 0-20
OD: 20-40
Schueler, 1987 j
1
Swale in low density
residential
FL
NA
NA
99 +
99 +
99 +
TKN: 99 +
BOD: 99
Monitoring study in
Brevard Co, Florida
Post, et al 1982 cited
in Whalen, et al,
1988
Swale for commercial
parking lot designed to
provide surface detention,
with a clay layer placed
below top soil layer to
prevent infiltration
NH
low
NA
Negli-
gible
Negli-
gible
25
50-65
50
TKN: 28
BOD: 11
Cu: 48
Cd: 42
NH3: 25-51
ON: Not sig.
NN: 32
Monitoring study in
Durham, NH; Over 11
storms monitored in
Durham, NH as part
of NURP.
Oakland, 1983, and
Athayde, et al 1983
cited in Whalen, et
al, 1988; Schueler,
1987; EPA, 1983;
British Columbia
Res. Corp, 1991
Swales
NA
NA
NA
Pollutants may reach ground water and discharge indirectly into receiving water
Whalen, et al, 1988
80040000H:\wp\Report\Roads\«ppend-a .tbl
A-9
Woodward-Clyde
January 29, 1993
-------
Management Practice: GRASSED SWALE
DESCRIPTI
ON
LOCA
TION
SLOPE
LENGTH
(FT)
REMOVAL EFFICIENCY (%)
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
STUDY
TYPE
REFERENCE
Swale
NA
NA
NA
80
80
60
Cu: 60
Compiled
from
literature
Horner, 1988
cited in British
Columbia Res.
Corp, 1991
Vegetative
Control
*
*
*
See
Chart
9096 of TSS removal
5096 of
TSS
removal
Cu: 6096 of TSS removal
~Generated
from
research, see
grass swales
along
highways
table
Hartigan, et al,
1989
Roadside
drainage
system -
grass swales.
Toront
o
residen
tial
NA
NA
Warm Cold
Weather Weather
Weighted
Storm Melt Total
Water Water Annual
90 13 28
Warm Cold
Weather Weather Weighted
Storm Melt Total
Water Water Annual
Flow: 90 13 20
Monitoring
conducted
1984-1985.
100 rains.
50 snowmclts
monitored.
Pitt and |
Mclean, 1986
cited in Pitt,
1986
Agricultural
vegetated, 1
foot channel,
4% cross
slope
DC
5%
30'length
58
19
7
-158
NH4:-11
TKN:9
P04:31
Runoff from
Agr. feedlot,
storm
simulated 2
yr in
POtomac
Region. Did
Dillaha et al,
1988
cited in
Casman, 1990
15' length
31
2
0
-82
NH4:1
TKN: 1
P04:-3
not capture
change in
filter
efficiency o
er time. 2
test runs
separated by
7 davs.
80040000H:\wp\Report\Roads\append-a.tbl
A-10
Woodward-Clyde
January 29, 1993
-------
Management Practice: GRASSED SWALES ALONG HIGHWAYS
WATER
-SHED
LENGTH
REMOVAL EFFICIENCY (%)
STUDY
DESCRIP-
TION
LOCATION
AREA
(Acres)
SLOPE
(FT)
TSS
TP
TKN
Pb
Zn
Cr
Ni
Cu
OTHER
TYPE
REFERENCE
Grass swale
along 1-4 @
Maitland
Florida
NA
0.896
160
91%
90%
44%
88%
41%
17 storm
events, 8
month
period.
Removal
efficiencies
vary by
storm
Yousef, et al,
1985
Grass swale
along 1-5 @
NE 158th
ADT =
100,000 veh
Washington
NA
220
80%
83%
69%
63%
Homer, 1982
cited in
Dupuis, 1985
Grass swale
along:
1-4 @ South
Orange
Blossom Trail
Florida
0.56 ac/
63%
imperv.
<3.5%
200
87-98%
-47 to
+ 26%
13-51%
33-94%
69-81%
29-65%
42-78%
NOx: 12-
52%
TOC:
58-66%
13 storms
monitored
Hartigan, et
al 1989
1-66
1-270
Virginia
Maryland
1.27 ac/
67%
imperv.
NA
4.7%
3.2%
200
200
52-65%
36-41%
-33 to
+ 12%
17-26%
3-46%
17-78%
8-98%
27-49%
18-47%
-34 to
+ 16%
5 - 83%
12-28%
-43 to
+22%
NOx: 2-
11%
TOC:
29-76%
Nox: -28
to-143%
12 storms
monitored
4 storms
monitored
Removal of metals correlated with TSS removal. Nutrient removal varies widely, appears unrelated to TSS removal. Results suggest that not only
channel lengths, but also channel slope and channel geometry (to reduce flow depth) also contribute to TSS removal, and metals removal
Grass lined
channel, flow
depth less
than 6 inches
Washington
NA
< 8%
200
80%
80%
COD:
80%
Washington
State, 1988
80040000H:\wp\Report\Roads\append-a.tbl
A-ll
Woodward-Clyde
Januaiy 29, 1993
-------
Management Practice: POROUS PAVEMENT
DESCRIPTION
LOCATION
WATER-
SHED
AREA
(Acres)
TREAT-
MENT
VOL.
(InMcre)
INFIL-
TRATION
RATE
(In/Hour)
REMOVAL EFFICIENCY (%)
STUDY TYPE
REFERENC
E
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Porous pavement -
partial exfiltration
Rockville, MD
NA
NA
NA
95
65
85
82
98
99
Pollutant export
over series of
storms monitored
at a terminal
underdrain and
compared to
runoff from
adjacent
conventional
pavement
OWML,
1983, 1986
cited in
Schueler,
1987
Porous Pavement -
partial exfiltration
Prince William,
VA
NA
NA
NA
82
65
80
Pollutant export
over series of
storms monitored
at a terminal
underd rain and
compared to
runoff from
adjacent
conventional
pavement
OWML,
1983, 1986
cited in
Schueler,
1987
80W0000H:\wp\Repoit\Roads\append-a.tbl
A-12
Woodward-Clyde
January 29, 1993
-------
Management Practice: CONCRETE GRID PAVEMENT
DESCRIPTION
LOCATION
REMOVAL EFFICIENCY (%)
STUDY TYPE
REFERENCE
REDUCTION IN STORM RUNOFF
3 types of grid pavements:
lattice, castellated and
poured-in place pavers, all
at 4 % slope
Lab
98.7 TO 100
Lab setting. Runoff volume and pollution
reduction associated for 10 simulated
rainfall events and most with return period
of less than 10 years
Day, 1981
Lattice papers (turfstone)
Downtown municipal
parking lot Dayton,
Ohio
65 to 97
Monitoring study for a period of 10 weeks
for 11 rain fall events with return period of
less than 2 years. The results were
compared to computer simulation of the
hydrological characteristic of the lot as if it
were paved in asphalt.
Smith, et al., 1981
80040000H:\wp\Report\Roads\append-a.tbI
A-13
Woodward-Clyde
January 29, 1993
-------
Management Practice: FILTRATION BASINS
DESCRIPTION
LOCATION
WATER-
SHED
AREA
(ACRES
TREAT-
MENT
VOL.
(In.Acre)
FILTRA-
TION
RATE
(In/Hour)
REMOVAL EFFICIENCY (%)
STUDY
TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Filter media
consisting of
varying layers of
gravel, sand
Lab
NA
NA
NA
80-95
30
BOD:70-90
OP: 50
Lab study
Wanielista, et
al 1981 cited
in City of
Austin, 1988
Filter media
consisting of alum
sludge/sand mixture
Lab
NA
NA
NA
80-90
90
BOD:70-90
OP: 90
Lab study
Wanielista, et
al 1981 cited
in City of
Austin, 1988
Test filter
Lab
NA
NA
NA
OP:75-92
Field study
Harper et al,
1982 cited in
City of Austin,
1988
In-line filtration
basin, overflows
when storage vol.
exceeded
Barton Creek
Square Mall,
Austin, TX
NA
NA
NA
78.3
27.3
33.3
59.5
BOD.-75.6
TOC:60.0
TDS:(-12.9)
NN:(-111.0)
Fe:55.0
FCol:80.7
Excludes
storms
which
overtop the
pond
Welborn et al,
1987 cited in
City of Austin,
1988
In-line filtration
basin, overflows
when storage vol.
exceeded
Barton Creek
Square Mall,
Austin TX
NA
NA
NA
58.1
49.9
32.4
38.7
47.4
BOD:75.6
TOC:50.0
TDS:8.9
NN:(-47.3)
TKN:49.4
Fe:49.2
FCol:82.9
Includes
storms
which
overtop
pond
City of Austin,
1988
Filtration basin -
filter media 3" sod,
4" course sand, 8"
gravel
Highwood
Apartments
Austin, TX
3 ac./50%
imperv.
1/2"
runoff
86
31
45
71
49
TP04:19
NN:(-5)
TKN:48
27 storms
monitored
between
1985-1987
City of Austin,
1990
Filtration basin -
filter media 18"
fine sand, 12"
coarse sand, 6"
gravel
Barton Creek
Square Mall,
Austin, TX
79 ac./7%
imperv.
1/2"
runoff
75
44
50
88
82
TP04:59
NO2+N03:
(-13)
TKN:64
30 storms
monitored
between
1985-1987
City of Austin,
1990
8(X)400(X)H:\wp\Report\Roads\append-a.tbl
A-14
Woodward-Clyde
January 29, 1993
-------
Management Practice: FILTRATION BASINS
DESCRIPTION
LOCATION
WATER-
SHED
AREA
(ACRES
TREAT-
MENT
VOL.
(In.Acre)
FILTRA-
TION
RATE
(In/Hour)
REMOVAL EFFICIENCY (%)
STUDY
TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Filtration basin -
filter media 12"
sand, filter fabric,
gravel
Jollyville,
Austin, TX
9.5
ac/81%
imperv.
1/2"
runoff
87
32
68
81
80
TP04:61
N02+N03:(-
79)
TKN:62
20 storms
monitored
between
1988-1989
City of Austin,
1990
Off-line
sedimentation/
filtration basin
Austin, TX
NA
equal or
less than
1/2"
runoff
80-
100
60-
80
20-
40
OD:40-60
M:60-80
BAC:40-60
Estimates
based on
above
noted
studies
City of Austin,
1990
On-line sand/sod
filtration basin
Austin, TX
NA
equal or
less than
1/2"
runoff
80-
100
0-20
20-
40
OD:20-40
M:40-60
BAC:20-40
Estimates
based on
above
noted
studies
City of Austin,
1990
On-line sand
filtration basin
Austin, TX
NA
equal or
less than
1/2"
runoff
60-80
40-
60
20-
40
OD:20-40
M:60-80
BAC:0-20
Estimates
based on
above
noted
studies
City of Austin,
1990
8(X)40000H:\wp\Rcpott\Roads\appcnd-a.tbl
A-15
Woodward-Clyde
January 29, 1993
-------
Management Practice: WATER QUALITY INLET - CATCH BASIN
DESCRI-
PTION
LOCA-
TION
WATER
-SHED
AREA
(Acres)
TREAT-
MENT
VOL.
(In/Acre)
REMOVAL EFFICIENCY (%)
STUDY
TYPE
REFERENCE
TSS
TP
SP
TN
NO
3
COD
Pb
Zn
OTHER
Catch
basin
cleaned 2
t^rnes a
year
Toronto
Residen
tial
NA
Warm Cold Weighted
Storm Melt Total
Water Water Annual
8 8 8
Monitoring
conducted
during
1984 &
1985. 100
rains, 50
snowmelts
monitored
Pitt &
McLean, 1986
cited in Pitt,
1986
Catch
basins -
cleaned 2
times a
year
Boston,
Mass.
NA
NA
60-
97
10-
56
BOC:
54-88
NA
Aronson,
1983 and '
Field, 1982
cited in Field,
1985
80040000H:\wp\Rcporl\Roads\appcnd-a.tbl
A-16
Woodward-Clyde
January 29, 1993
-------
Management Practice: WATER QUALITY INLET - CATCH BASIN WITH SAND FILTER
DESCRIPTION
LOCATION
DRAINAGE
AREA
LOCATION
REMOVAL EFFICIENCY (%)
STUDY TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Catch Basin with
sand filter
\
Austin, Texas
5 ac max
75-86
31-44
45-68
71-88
49-80
Monitoring studies
by City of Austin,
Texas for 3
filtration sites:
Highwood, BCSM
and Jollyville 1.
Removal rates for
pollutants have
not been widely
tested, but they
are expected to
have removal
efficiencies similar
to those of
filtration basins
for highly
impervious
drainage areas that
are less than 5
acres. Results of
monitoring studies
for filtration
basins in Austin,
Texas is med.
Shaver, 1991
80040000H:\wp\Rcport\Roads\appcnd-a. tf>I
A-17
Woodward-Clyde
January 29, 1993
-------
Management Practice: WATER QUALITY INLET/OIL-GRIT SEPARATORS
WATER-
SHED
AREA
(Acres)
TREAT-
MENT
VOL.
(In/Acre)
REMOVAL EFFICIENCY (%)
DESCRIPTION
LOCATION
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
STUDY
TYPE
REFERENC
E
Water quality
inlet - 3 chamber
NA
1 ac
impervio
us area
max
400 cu ft
wet storage
per
impervious
acre
0-20
Insuff.
knowledge
Insuff.
knowledge
Insuff.
knowledge
insuff.
knowledge
Insuff.
knowledge
BAC insuf.
knowledge
Pollutant
removal
capability
of water
quality
inlets has
never been
tested in
the Geld,
but some
general
estimates
inferred
from
studies on
similar
structures
such as
catch
basins and
oil/water
separators.
Schueler,
1987
Catch basin 3
chamber-
cleaned twice a
y-
NA
1 ac max
NA
10-25
5-10
5-10
5-10
10-25
5-10
Nutrients 5-10
Large particles
- 50% eff.
Finer particles
assoc. w/large
portion of
heavy metals
and organic
pollutants
re suspended.
Pitt, 1985
cited in
Schueler,
1987 and
City of
Austin, 1988
80040000H:\wp\Rcport\Roads\£ppcod-a.lbl
A-18
Woodward-Clyde
January 29, 1993
-------
Management Practice: STREET CLEANING - POLLUTANT REMOVAL IN RUNOFF WATER
DESCRIPTION
LOCATION
WATER-
SHED
AREA
(Acres)
REMOVAL EFFICIENCY (%) IN RUNOFF
STUDY TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Street cleaning on
smooth streets.
One or more
passes/week
One pass/2 weeks
One pass/month
One pass/2 months
One pass/3 months
Toronto
residential
NA
Warm Cold
Weather Weather Weighted
Storm Melt Total
Water Water Annual
25 0 5
23 0 5
20 0 4
16 0 3
13 0 3
Outfall & source
area monitoring
conducted during
1984 & 1985. 100
rains, 50 snowmelts
monitored
Pitt & McLean,
1986
Street cleaning on
rough streets
One or more
passes/week
One pass/2 weeks
One pass/month
One pass/2 months
One pass/3 months
Toronto
residential
NA
Warm Cold
Weather Weather Weighted
Storm Melt Total
Water Water Annual
15 0 3
12 0 2
10 0 2
7 0 1
6 0 1
Outfall & source
area monitoring
conducted during
1984 & 1985. 100
rains, 50 snowmelts
monitored
Pitt & McLean,
1986 cited in
PiH, 1986
Broom street
sweeping
National
NA
No significant reduction in urban runoff quality except in areas with accelerated pollutant accumulations
(commercial and industrial zones) and in areas with direct surface water runoff to the receiving body.
NURP studies
monitored 381 storm
events under control
conditions and 277
during street
sweeping operations
EPA, 1982 cited
in City of Austin,
1988
Rotary broom
sweeper
Bellevue,
Washington
NA
No decrease and possible increase in loadings of solids in runoff from city streets
NURP study
Cited in Puget
Sound Water
Quality
Authority, 1989
Street sweeping .
National
NA
Ineffective in 4 out of 5 areas studied
NURP study
Cited in Puget
Sound Water
Quality
Authority, 1989
Street cleaning, 3
passes/week
Castro Valley,
Alameda
County, CA
NA
Less
than 10
35
TS:20
Cu: Less
than 10
In-situ, NURP
funded
Cited in Pitt, et
al, 1981
80040000H:\wp\Report\Roads\append-a.tbl Woodward-Clyde
January 29, 1993
A-19
-------
Management Practice: STREET CLEANING - POLLUTANT REMOVAL IN RUNOFF WATER
DESCRIPTION
LOCATION
WATER-
SHED
AREA
(Acres)
REMOVAL EFFICIENCY (%) IN RUNOFF
STUDY TYPE
REFERENCE
TSS TP SP TN N03 COD Pb Zn OTHER
Street sweeping
National
NA
o Based on statistical testing, no significant reductions in EMCS are realized by street sweeping,
o Benefits of street sweeping, if any, are not large (i.e. greater than 50%), and an even larger site
data base is required to identify the possible effect,
o Street sweeping increasing EMCS generally not shown by the data, though it could occur in
isolated, site specific cases.
5 NURP projects, 10
sites, compared end-
of-pipe
concentrations for
adjacent swept and
unswept basins
Cited in EPA,
1983
80040000H:\wp\Report\Roads\app«id-a.tbl
A-20
Woodward-Clyde
January 29, 1993
-------
Management Practice:
STREET CLEANING - POLLUTANT REMOVAL ON STREET SURFACE
DESCRIPTION
LOCATION
WATER-
SHED
% REMOVAL ON STREET SURFACE
STUDY
TYPE
REFERENCE
AREA
(Acres)
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Intensive street
cleaning programs
NA
NA
TS: 25-50
NA
Pitt, 1985 cited in
City of Austin,
1988
Broom sweeper
Virginia
NA
40
42
31
35
47
BOD: 43
TS: 55
NA
NVPDC, 1979 cited
in City of Austin,
1988
Vacuum sweeper
Virginia
NA
74
77
63
76
85
BOD: 77
TS: 93
NA
NVPDC, 1979 cited
in City of Austin,
1988
Street sweeping
Wise.
NA
TS: 10
NURP study
in Wise.
SEWRPC, 1983
cited in City of
Austin, 1988
Street cleaning -
mechanical and
vacuum-assisted
mechanical,
frequency varied
between 2 passes per
day and less than 1
pass per week:
Asphalt in good
condition
Asphalt in poor
condition
San Jose, CA
NA
30-60
40
5-12
30-60
40
5-12
30-60
40
5-12
TS: 30-60
TKN: 30-60
OP: 30-60
TS: 40
TKN: 40
OP: 40
TS: 5-12
TKN: 5-12
OP: 5-12
In-situ
Removal
efficiencies
for COD,
TKN, Pb,
OP, Zn, Cr,
Cu, Cd
approx equal
toTS
Pitt, 1979 cited in
Finnemore, 1982
Rough oil and
screenings surface
80040000H:\wp\Rcport\Roads\appcnd-a.tbl
A-21
Woodward-Clyde
January 29, 1993
-------
Management Practice:
STREET CLEANING - POLLUTANT REMOVAL ON STREET SURFACE
DESCRIPTION
LOCATION
WATER-
SHED
AREA
(Acres)
% REMOVAL ON STREET SURFACE
STUDY
TYPE
REFERENCE
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
Mechanical sweeping
RA Vacuum
Castro Valley,
Alameda
County, CA
Castro Valley,
Alameda
County, CA
NA
47-65%
59-71 %
54-63%
58-74%
52-66%
60-71%
TS: 53-64
TKN: 50-63
OP: 52-64
Cu: 55-64
TS: 61-69
TKN: 60-72
OP: 58-70
Cu: 57-70
RA is most
effective in
cleaning
streets with
light
loadings; as
loadings
become
heavier, the
difference
between the
two becomes
insignificant.
Cited in Pitt, et al,
1981
Street sweeping, 4
passes per month
(1/week)
Wisconsin:
Residential
NA
2%
8-12%
TS: 4
Simulation
model studies
Cited in
Southeastern
Wisconsin Regional
Planning, 1991
Commercial
NA
36%
53%
TS: 47
Industrial
NA
27%
37%
TS: 28
Street cleaning,
Cleaning
One
Two
Three
NA
Adimi, 1976 cited
mechanical sweeper
Frequency Pass
Pass
«s Passes
in Young, et al,
efficiency as a
(Days')
(%)
1982
function of sweeping
frequency and
60
41.0
74.0
94.8
number of passes
30
60.5
87.9
97.6
14
66.0
92.1
98.4
7
75.5
95.0
99.0
1
79.4
96.4
99.3
80040000H:\wp\Rcport\Roads\appcnd-a.tbI
A-22
Woodward-Clyde
January 29, 1993
-------
he Pollutant Removal Capability of Pond and Wetland Systems: A Review
NOTK: The table below provides summary data (in the pollutant removal capability of nearly sixty stormwater pond and wetland systems. Kuch
study differs with respect to pond design, number of storms monitored, pollutant removal calculation technique, and monitoring
technique, so exact comparisons between studies are not appropriate.
Nole: An asterisk (•) denotes in Inferred value
able taken from Schueler ^t al. 1992
80CM0000H:\wp\Report\Roads\append-a.tbl
A-23
Woodward-Clyde
January 29, 1993
-------
The Pollutant Removal Capability of Pond and Wetland Systems: A Review
TYPE
NO.
I
NAME
STATE
NO. OF
STORMS
WATER-
SHED
AREA
(Ac ret)
TREAT-
MENT
VOL.
(In./Acrc)
REMOVAL EFFICIENCY (%)
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
WET PONDS
7
Seattle
WA
5
0.75
86.7
78.4
64.4
65.1
65.2
Cu: 66.5
8
Boynton Beach
FL
8
91.0
76.0
87.0
TKN: 58.0
9
Grace Street
MI
18
VBA'R=.52
32.0
12.0
6.0
(-1.0)
26.0
TKN: 7.0
BOD: 3.0
10
Pitt-AA
MI
6
4872.0
VB/VR=0.52
32.0
18.0
7.0
23.0
62.0
13.0
TKN: 14.0
BOD: 21.0
11
Unqua
NY
8
VB/VR=3.07
60.0
45.0
80.0
TOC: 7.0
12
Waverly Hilli
MI
29
VB/VR=7.57
91.0
79.0
62.0
66.0
69.0
95.0
91.0
Cu: 57.0
TKN: 60.0
BOD: 69.0
13
Lake EUyn
IL
23
VB/VR= 10.70
84.0
34.0
78.0
71.0
Cu: 71.0
14
Lake Ridge
MN
20
315.0
0.08
A: 90.0
B: 85.0
61.0
37.0
11.0
8.0
41.0
24.0
10.0
17.0
73.0
52.0
TKN: 50.0
TKN: 28.0
IS
West Pond
MN
8
76.0
0.15
65.0
25.0
61.0
8.0-79.0
66.0
TOC: 19.0
TKN: 23.0
Cr: 48.0-76.0
Cd: 12.0-91.0
16
McCarrons
MN
21
608.0
0.19
91.0
78.0
85.0
90.0
90.0
17
McKiilght Basin
MN
20
725.0
0.22
A: 85.0
B: 85.0
48.0
34.0
13.0
12.0
30.0
14.0
24.0
11.0
67.0
63.0
TKN: 31.0
TKN: 15.0
18
Monroe Street
WI
238.0
0.26
90.0
65.0
70.0
70.0
70.0
65.0
Cu: 75.0
FColi: 70.0
Pest: 25-50.0
Hydro: 75-90
19
Runaway Bay
NC
5
437.0
0.33
54.0
24.0
42.0
TKN: 20.0
Nolr: An ulrrlsk (~) dmota mi Inferred vaIuc
Table taken from Schueler et al, 1992
80040000H:\wp\Report\Roads\appead-a.tbl Woodward-Clyde
January 29, 1993
A-24
-------
The Pollutant Removal Capability of Pond and Wetland Systems; A Review
I
NO. OF
WATER-
SHED
TREAT-
MENT
RKMOVAL KKKICIKNCY <%)
TYPE
NO.
NAME
STATE
STORMS
AREA
(Acre.)
VOL.
(In./Acre)
TSS
TP
SP
TN
N03
COD
Pt>
Zn
OTHER
20
Buck! and
CT
7
20.0
0.40
61.0
45.0
22.0
18.0-59.0
51.0
Cd: <0
TKN: 24.0
TOC: 33.0
Cu: 38.0
21
Highway Site
FL
13
41.6
0.55
65.0
17.0
21.0
7.0
41.0
37.0
22
Woodhollow
TX
14
381.0
0.55
54.0
46.0
39.0
45.0
41.0
76.0
69.0
TKN: 26.0
NH3: 28.0
BOD: 39.0
FColl: 46.0
23
SR 204
WA
5
1.8
0.60
99.0
91.0
69.1
88.2
87.0
Cu: 90.0
24
Form Pond
VA
51.4
1.13
85.0
86.0
73.0
34.0
NH3: (-107.0)
25
Burke
VA
29
27.1
1.22
(-33.3)
39.0
77.0
32.0
21.0
84.0
38.0
WET PONDS
26
Weatleigh
MD
32
48.0
1.27
81.0
54.0
71.0
37.0
35.0
82.0
26.0
TKN: 27.0
(Cont'd)
27
Mercer
WA
5
7.6
1.72
75.0
67.0
76.9
23.0
38.0
Cu: 51.0
28
1-4
FL
6
26.3
2.35
54.0
69.0
97.0
41.0-94.0
69.0
TOC: 45.0
TKN: 68.0
Cd: 43.0-51.0
Cu: 66.0-81.0
29
Timber Creek
FL
9
122.0
3.11*
64.0
60.0
80.0
15.0
80.0
30
Maitland
FL
30-40
49.0
3.65
90.0
87.0
95.0
96.0
PP: 11.0
Cu: 77.0
NH3: 82.0
31
Lakeaide
NC
5
65.0
7.16
91.0
23.0
82.0
TKN: 6.0
N»le: An ixlerlsk (•) dcatrfe* ta Inferred v»Iim
Table taken from Schueler et al, 1992
80040000H:\wp\ReportVRoads\append-a.tbl
A-25
Woodward-Clyde
January 29, 1993
-------
The Pollutant Removal Capability of Pond and Wetland Systems: A Review
TYPE
NO.
I
NAME
STATE
NO. OF
STORMS
WATER-
SHED
AREA
(Acre.)
TREAT-
MENT
VOL.
(In./Acre)
rkmoval fkkiciency <%i
TSS
TP
SP
TN
N03
COD
Pb
Zn
OTHER
WET ED
32
; Uplands
-y J;
ONT
i'.S- ¦¦
#!;??;
. 860.0
t n. '.'ti .r
M
82.0
'•?' V"
69.0
v:-*; •
FColl: 97.0
V- •
33
rEut Banhavco
ONT,
2139.0'
•* ?' ¦
lis
> • 'iTi
47.0,
"J- 4
Iff'!
;!f- i."
tv-'- i.
v;MW:
FCoU: i56.0
34
Kennedy-Burnett
ONT
¦¦ « ¦
• llv -l'-
,395.0 .
v'O 62 * * •
¦, 98-0,
?r.'v„
.79.0 '
- J . V v
(; *
ir v-v-
.,54.0
1y:-7
N - u,
1 r.' <
j&k
¦ 139.0.
-
,21,0,
,Vt "
BOD: 36.0
FColl; 99.0
STORMWATER
WETLANDS
33
EWA3
IL
72.0
59.0
70.0
Fa: 48.0
36
EWA4
IL
76.0
55.0
42.0
Fe: 43.0
37
EWA5
IL
89.0
69.0
70.0
Fe: 50.0
38
EWA6
IL
98.0
97.0
95.0
Fe: 92.0
39
B31
WA
13
461.7
0.01
14.0
(-2.0)
4.0
40
PC12
WA
13
214.8
0.03
56.0
(-2.0)
20.0
41
McCarrona
MN
21
608.0
0.31
87.0
36.0
24.0
79.0
68 0
42
Queen Aiuie's
MD
0 50*
65.0
39.0
44.0
23.0
55.0
NH4: 55.0
ON: (-5.0)
PP: 7.2
43
Swift Run
Ml
5
1207.0
0.60
85.0
3.0
29.0
80.0
2.0
82.0
BOD: 4.0
44
Tampa OITicc Pond
FL
3-8
6.3
0.61
64.0
55.0
65.0
34.0
ON: (-3.7)
45
Highway Site
FL
13
41.6
0.SI
66.0
19.0
30.0
18.0
75.0
50.0
46
Palm Beach PGA
FL
2340.0
2.00*
50.0
62.0
33.0
NH3: 17.0
BOD: 35.0
TOC: 10.0
TKN: 16.0
ED WETLANDS
47
Ba\Jamln Franklin
VA
'»
1
40.0
i-i *¦
0.08 '
- V ' • ' ' Jf
'-lii'l' -f
62.0
'M
14.9
23.6
.frv »*
¦-
! .
' \ ' . *
J. I-
r i ¦ I
.60.0
(-73.5)
C""5:-'
Cd: (-79.8)
NH3: ' 0.0
TKN: 4.4
Note: An asterisk (•) devotes in Inferred vaJut
Tabic taken from Schueleret al, 1992
80040000H:\wp\Report\Roads\ap|>end-a.tbl
A-26
Woodward-Clyde
January 29, 1993
-------
Table L LITERATURE RESEARCHED TO INVESTIGATE PERFORMANCE CHARACTERISTICS OF WETLANDS
Study
Location
Name/LD.
Dcicnrinn Pood
/Wetland
Coo meted
/Natural
Wetland
Oassificaton
Martin and Smoot
1986
Orange County,
Fkrrida
Orange County
Treatment System
detention pood
wetland
constructed
hardwood
cypress dome
Harper etaL
1986
Florida
Hidden Lake
wetland
natural
hardwood
swampland
Reddy etaL
1982
Orange Coowy,
Florida
I ah* Apopka
wetland
constructed
march
Blackburn et aL
1986
Palm Beach,
Florida
Palm Beach PGA
Treatment System
wetland
constructed
and natural
southern
marshland
Esry and Cairns
1988
Tallahassee,
Florida
Jackson Lake
detention pood
wetland
constructed
southern
marshland
Brown, R.
1985
Twin Cmes Metre
Area,
Minnesota
Twin CSriea Metro
wetlands
natural
and
constructed
northern
peatland
Wotzka and Oberts
1988
Rosevilk,
Minnesota
McCanons
Treatment System
pood
wetland
constructed
-------
Tabic L LITERATURE RESEARCHED TO INVESTIGATE PERFORMANCE CHARACTERISTICS OF WETLANDS
Study
Location
Name/1. D.
Detention Pood
/Wetland
Coasuucted
/NitnnJ
Wetland
CUssific&loo
Meiorin
19S6
Fremont,
California
DUST Marsh
/
wetland
constructed
bnddsfa marsh
Momj etaL
1981
Taboe Bum,
California
Taboe Baain
Meadow land
wetland
constructed
?
0
high eleviaoo
riverine
Scberger «nd Davis
1982
Am Albor,
Michigan
Pittifi eld-Ann Arbor
Swift Ron
detention pood
wetland
ooDStmcted
and
ntniral
northern
putUod
ABAG
1979
Palo Alto,
California
Palo Alto Marah
wetland
utunl
bricidah marsh
Jolly
1990
SL Agatha,
Maine
Long Lake Wetland-Pood
Treatment System
pood
wdUad
oanfiruaed
Oberu et *1
1989
Ramsey-Washington Tinners Lake, McKnigfal
Metro Area, Lake, Lake Ridge, and
Minnesota Carver Ravine
drtmrion poodi
wctlaadi
cocfirocted
cattail marsh
Reinell et iL
1990
King Canty.
Washington
B3I and PC12
wctlaods
p»mnd
palunrine
Ruihtoo and Dye
1990
Tampa,
Florida
Tampa Office Pood
wetland
constructed
f ntil fTj«pth
Hey and Barren
1991
Wadswonh,
Illinois
Dea Plainca River Wetland
Demonstration Project
wetland
coaaructed
freshwater
riverine
Taken from Woodward-Clyde, 1991
Woodward-Clyde
January' 29, 1993
80040000H:\wp\Report\Ro»ds\append-a.tbl
A-28
-------
Table 2. AVERAGE REMOVAL EFFICIENCIES FOR TOTAL SUSPENDED SOLIDS AND NUTRIENTS IN WETLANDS REPORTED IN THE LITERATURE
Study
Svstem Name
SvitemTVoe
Martin and Smoot
Orange County
detention pond *
1986
Treatment System
wetland *
entire ryrtem
Harper eta].
Hidden LaJce
wetland
193
-------
Table X AVERAGE REMOVAL EFFICIENCIES FOR METALS AND OIL AND GREASE IN WETLANDS REPORTED IN THE LITERATURE
Study
¦§X&SUii5&&
Martin and Smoot
Orange County
detention pood •
1986
Treatment System
wetland *
entire ryitem
Harper et aL
Hidden Lake
wetland
1986
Reddy et aL
Lake Apopka
reaervoirt
1986
flooded fleldt
Blackburn et aL
Palm Beach POA
lyitem
1986
Treatment Syitem
Eary andCaimi
Jackson Lake
system
1988
Brown
F1 ibLake
wctlsrvVpond
1985
Laka Elmo
wetland
Laka Riley
wetland
Sprint Lake
wetland
Wotzka and Obert
McCamxu Wetland
detention pond *
1988
Treatment System
wetland *
system
Hlckok et al.
WayiaU Wetland .
wetland
1977
Bsrtcn
dear Lake
wetland
1987
Mdorln
DUST Manh
1986
Bat in A
wetland •
Basin B
wetland *
BaitnC
wetland*
Syttem
wetland
Morrii et al.
Angora Geek
wetland
1981
Tallac Lajtoon
wetland
Schergcr and Davii
Pittafleld-Ann Arbcr
detention pond •
1982
Swift Run
wetland
ABAO
Palo Alto Manh
wetland
1979
Jolly
Long Laka Wetland-Pond
endre system
1990
Treatment Svitera
Otxru ct aL
Tama* Laka
detention pond *
1989
McKnl&ht Lake
detention ponds *
LakeRidgo
wetland
Carver Ravine
wetland-pond lystem
Relneh et aL
B3I
wetland
1990
PC12
wetland
Ruibton and Dye
Tampa Office Pond
wetland
1990
Hey and Barrett
Dea Plalnei River Wetland
1991
HWA 3
wetland
HWA 4
wetland
EWA 5
wetland
EWA6
wetland
Median pollutant efficiency for wetland ryrtemi (without *)'.
Negative removal efficiencies indicate net export In pollutant loadi.
Lead
Zine
Copper
Cadmium
Nickel
Chromium Oil and
total
dissolved
total
dissolved
total dissolved
total dissolved
total dissolved
total dissolved Grease
39
29
15
-17
73
54
56
75
83
70
70
65
55
56
41
57
40 29
71 79
70 70
73 75
S3
68
90
94
30
27
S3
8S
61
S3
39
63
32
6
83
63
82
42
24
•29
42
34
42
80
67
•20
•60
17
-19
36
-12
11
26
53
47
13
66
32
-57
13
-25
61
40
29
69
79
48
70
70
75
Taken from Woodward-Clyde, 1991
80040000H:\wp\Report\Roads\append-a.tbl
A-30
Woodward-Clyde
January 29, 1993
-------
Table 4. WETLAND GEOGRAPHIC AND HYDRAULIC CHARACTERISTICS
Study
1
System Name
Watershed
Land Use
%
Land Use
System
Type
Wetland Watershed Wetland/
Size Size Watershed
(acres) (acres) Ratio
Average
Flows
1.
1986
Hidden Lake
residential
NA
wetland
2.5
55.2
4.5%
0.22
NA
NA
NA
diffuse
• The wetland is not« basin, but similar to a grassy swale.
Reddy et al.
1982
Lake Apopka
agriculture
100
reservoirs
flooded fields
0.9
0.9
NA
NA
0.56
0.23
2.6
0.6
9.4 days
4.8 days
3.3
0.7
diffuse
• Design configuration suggests Utile short circuiting occurred.
Blackburn el al.
1986
Palm Beach POA
Treatment System
residential
ItoLf course
NA
wetland
wetland
89
296
2350
3.8%
12.6%
NA
NA
NA
NA
diffuse
• Design configuration suggests little short circuiting occurred.
• Oenerally sheet flow exists within the artificial wetland.
Ersy and Calrnl
1983
Jackson Lake
urban
NA
detention pond
wetland
20
9
2230
© o
>- vo
* *
NA
150
13.5
NA
7.5
1.5
diffuse
• Design configuration suggests little short circuiting occurred.
Brown
198S
Fish Lake
residential
commercial
agriculture
open
30
5
12
JJ
wetland
16
700
2-3%
0.001-0.01
64
NA
4
discrete
• The major influent to these naairal wetlands is
discrete channelized flow.
• The schematic suggests large areas of dead storage.
Lake Elmo
residential
commercial
agriculture
open
12
1
34
53
wetland
225
2060
10.9%
0.001-0.65
900
NA
4
discrete
• Short circuiting was not discussed by the author.
Lake Riley
residential
commercial
agriculture
open
13
2
30
55
wetland
77
2475
3.1%
0.004-IJ5
231
NA
3
discrete
Spring Lake
residential
commercial
agriculture
open
5
1
57
37
wetland
64
5570
1.1%
0.008-4
256
NA
4
discrete
Wotzis and Obat
1988
McCarrons Wetland
Treatment System
urban
NA
detention pond
wetland
system
2.47
6.2
8.67
600
0.4%
1.0%
1.4%
0-QS-.2
2J-9.7
24 days
Z5
diffuse
diffuse
• Three discrete inlets help to minimize short circuiting and
dissipate surface water energy.
Hickok et il.
1977
Wayiala Wetland
residential
commercial
NA
wetland
7.6
65.1
11.7%
0.08
NA
NA
NA
discrete
• Design configuration suggests minimal short circuiting
existed regardless of a single discrete inlet.
Boten
1987
~ear Lake
urban
NA
wetland
32.9
1070
4.9%
1.5
10
3-5 days
OS
diffuse
Meiorin
1986
DUST Marsh
urban
agriculture
93
7
wetland A
wetland B
wetland C
wetland (system)
5
6
21
32
2960
0.2%
0.2%
0.7%
1.1%
10-250
150
4-40 days
4.7
diffuse
• Design configuration suggests little short circuiting occurred
due to long and narrow wetland basins.
Morris et al.
1981
Angora Creek
Tallac Lagoon
wetland
wetland
NA
NA
2816
2781
NA
NA
8.46
8.68
NA
NA
NA
NA
NA
NA
diffuse
diffuse
• Plow occur* as channelized flow until the storm volume
is large enough to force sheet flow through the meadow lands.
Schergcr and Davli
1982
Pittsfield-Ann Arbor
Swift Run
residential
commercial
agriculture
open
45
19
13
23
detention pond
wetland
25.3
25.5
4872
120T
0.5%
2.1%
0-2916
0-166
21-176
15-60
4-105
12-82
0-6
0-3
discrete
discrete
• The schematic suggests large areas of dead storage exist.
Taken from Woodward-Clyde, 1991
80040000H:\wpVRcport\RoadsVappcnd-a.tbl
A-31
Woodward-Clyde
January 29, 1993
-------
Tabic 4. WETLAND GEOGRAPHIC AND HYDRAULIC CHARACTERISTICS (concluded)
Wetland Waurshed Wetland/
Average
Bum
Delation
Watershed
%
System
SUe
Size
Watershed
Flowt
Volume
Time
Depth
Inlet
Study
System Name
Land Uie
Land Uae
Type
(acre.)
(acres)
Ratio
(aem-A)
(hours)
w
Condition
Comments
ABAC)
Palo Alto Marsh
residential
62
wetland
613
17600
3.5%
150-320
400-750
30
1-6
discrete
• Water level end rohunc aro controlled by the lid&l cycle.
1979
commercial
12
• Channelized flow exist until the tide increases caujmg
open
26
the surrounding mtnh to become Inundated.
Jolly
Long Lake Wetland-Pond agriculture
100
wetland-pood
M
It
83%
aoi
1.5
NA
0.5-1
diffuse
• Entire systemcoraiiti of a sedimentation basin, gran filter
1990
Treatment System
strip, constructed wetiind, end deep pond.
Oberu et al.
Tamers Lake
residential
NA
pond
0.07
1134
negligible
NA
0.1
NA
3.0
discrete
• Monitoring occurred during a dry period.
1989
McKnlghtLako
residential
NA
pond
Si]
5217
0.1%
NA
13.2
NA
4.9
discrete
Lake Ridge
residential
NA
wetland
0.94
531
0.2%
NA
10
NA
4.1
discrete
Carver Ravine
residential
NA
wetland-pond
0J7
170
0.2%
NA
1.0
NA
10
discrete
Rcinett et al.
B31
urbanized
NA
wetland
4.9
461.7
1.1%
1.5
0.03-0.43
3 J
NA
discrete
• Storm flowt reduce detention times.
1990
PC12
rural
NA
wetland
3.7
214 J
1.7%
0.7
0.05-0.60
10
NA
discrete
• Qumeltzjlion reduced effective srea in wed and
Ruihton and Dye
Tamp* Office Pond
commercial
100
wetland
033
6.3
5.6%
NA
0.32
NA
0-U
discrete
• Overflow from adjacent wetlands occurred during extremely
1990
high water leak and breach problems occurred during study.
Hey and BanetJ
Dei Plainti Rlvo Wetland
NA
NA
EWA 3
5.6
•
•
5
NA
NA
I
discrete
• Waur is pumped to (he system from (he river (eft-linage area
1991
Danonraatlon Project
NA
NA
EWA 4
5.6
•
•
0.6
NA
NA
1
discrete
of 210 squire milej) for 20 hours per week.
NA
NA
EWA 5
4J
¦
.
4
NA
NA
1
discrete
NA
NA
EWA 6
8.3
-
•
1
NA
NA
1
discrete
NA a Not available
Taken from Woodward-Clyde, 1991
80040000H:\wp\Report\Roadj\append-a.tbl
A-32
Woodward-Clyde
January 29, 1993
-------
Table 5. SAMPLING CHARACTERISTICS FROM THE WETLANDS REVIEWED
Study
Location
Time
ofStndv
Length of
Study
Type
Sample
Number
of Storms
Monitored
Method of Computing
Efficiencies
Martin and Scnoot
1986
Orange County,
Florida
1982-1984
2 yean
7 wmlri gnb
6 oompocitfi
13
ROL
Harper etaL
1986
Florida
1984-1983
1 year
onmpotile
18
ER
RcddyetaL
1982
Orange County,
Florida
1977-1979
2 ycxn
nng^e grab
-150
MC
Blackburn et iL
1986
Palm Beach,
Florida
198S
1 year
single gnb
36
MC
Eny and Cairns
1988
Tallahassee,
Florida
198S
NA
NA
1
NA
Brown
1985
Twin Citi^«
Metro Area,
Minneaou
1982
1 year
onmpoche
5-7
SOL
Wot rial and Obota
1988
RoaeviDe,
Minneaou
1984-1988
2year»
25
ROL
HickoketaL
1977
Minnesota
1974-1975
lOmcaiha
KA
NA
SOL
Bartrn
1987
Waaeca,
Minneaou
1982-19&5
3 yean
ooopocae
27
ER
Meiorin
1986
Coyote Hni«
Fremont, Ca.
1984-1986
2 yean
mmpneitft
11
SOL
Morris ctaL
1981
Tahoe Basin,
California
1977-1978
1 year
cngir. gnb
-75
MC
1 Sdierger and Davis
1982
Ann Arbor,
Michigan
1979-1980
8 month*
oovnpoche
7
SOL
ABAG
1979
Palo Alto,
California
1979
3 months
8
HR
- Jolly
1990
Sl Agatha,
Maine
1989
5 months
nrwnpncitA
11
SOL
ObenictaL
1989
Ramsey-Washington
Metro Area.
Minneaou
1987-1989
2yean
rmmfwit*
7-22
SOL
Rein ell et aL
1990
King Cowty,
Washington
1988-1990
2yean
composite
13
SOL
Rush loo and Dye
1990
Tampa,
Florida
1989-1990
12 months
oncrrpocilc
3-8
ER
Hey and Barren
1991
Wadsworth,
niirxxj
1990
8 months
discrete
cooanttous
SOL
Tahle Notes:
HR * Event mem cocceomtiaa
SOL » Sum of event loads
ROL ¦ Regression of event load]
MC ¦ Mean concentntioa
KA » Not available
Taken from Woodward-Clyde, 1991
80040000H:\wp\Report\Roads\append-a.tbl
A-33
Woodward-Clyde
Januaiy 29, 1993
-------
NOTATION
BAC: Bacteria
BOD: Biological Oxygen Demand
Cd: Cadmium
COD: Chemical Oxygen Demand
Cr: Chromium
Cu: Copper
FCol: Fecal Coli
Fe: Iron
N: Nutrients
NH3: Ammonia
NN: Nitrate/Nitrite
N03: Nitrate
OD: Oxygen Demand
ON: Organic Nitrogen
OP: Ortho-Phosphorus
Pb: Lead
SP: Soluble Phosphorus
TDS: Total Dissolved solids
TKN: Total Kgeldahl Nitrogen
TM: Trace Metals
TN: Total Nitrogen
TOC: Total Organic Carbon
TP: Total Phosphorus
TS: Total Solids
TSS: Total Suspended Solids
Zn: Zinc
NA: NOT AVAILABLE
80040000H: \wp\Rcpoit\Roads\append-a-tbl
A-34
Woodward-Clyde
January 29, 1993
-------
COMPUTER RUNS TO DETERMINE REMOVAL EFFICIENCY OF
INFILTRATION BASINS AND TRENCHES IN VARIOUS REGIONS
Woodward-Clyde
80040000Hi\wp\Report\Roads\append-a .tbl January 29, 1993
A-35
-------
PACIFIC NORTHWEST
Mean Coef, of Variation
Volume 0.5 1.09
Intensity 0.035 0.73
Duration 15.9 0.8
Interval 123 1.5
Area= 1 ac
Rv= 0.5
Volume= 90% ave runoff 817 cf
(0.23 in. runoff) (1 ac * 0.50 * 0.50 in * 90%)
QR VR
63.525 907.5
* * *
* * *
Perc.
Height
Surf. Area
* Fig 4*
*Fig 1*
*Fig 3
Rate (in/hrt
M
(sa.fU
QT
QT/QR
VB
VB/VR
E
VE/VR
% FLOW
% VOL
8.27
2
408.4
281.4
4.43
816.8
0.9
38.1
0.9
100
58.0
2.41
3.2
255.2
51.3
0.81
816.8
0.9
6.9
0.9
66
58.0
2.41
8
102.1
20.5
0.32
816.8
0.9
2.8
0.9
31
58.0
1
1.2
680.6
56.7
0.89
816.8
0.9
7.7
0.9
68
58.0
1
2
408.4
34.0
0.54
816.8
0.9
4.6
0.9
48
58.0
1
5
163.4
13.6
0.21
816.8
0.9
1.8
0.8
19
55.0
0.5
3
272.3
11.3
0.18
816.8
0.9
1.5
0.8
16
55.0
0.27
8
102.1
2.3
0.04
816.8
0.9
0.3
0.3
0
23.0
100.0
85.7
71.0
86.6
78.2
63.6
62.2
23.0
Computed from Woodward-Clyde, 1986
80040000H:\wp\Repoit\Roadj\append-a.tbl
A-36
Woodward-Clyde
January 29, 1993
-------
PACIFIC SOUTH
Per c,
Mean Coef. of Variation
Volume
0.54
0.98
Intensity
0.054
0.76
Duration
11.6
0.78
Interval
476
2.09
Area =
1 ac
Rv =
0.5
Volume =
90% ave runoff
871
cf
(0.24 in. runoff)
(1 ac * 0.50
* 0.54 in * 90%)
cm
¥E
98.01
980.1
* * ~
Height
Surf. Area
~Fig 4*
*Fig 1*
* Fig 3
(in/hr)
m
(sq.ft.)
QI
QT/QR
VB VB/VR
E VE/VR
% FLOW
% VOL
% REMOVA
8.27
2
435.6
300.2
3.06
871.2 0.9
145.8 0.9
100
58.0
100.0
2.41
3.2
272.3
54.7
0.56
871.2 0.9
26.6 0.9
50
58.0
79.0
2.41
8
108.9
21.9
0.22
871.2 0.9
10.6 0.9
21
58.0
66.8
1
1.2
726.0
60.5
0.62
871.2 0.9
29.4 0.9
54
58.0
80.7
1
2
435.6
36.3
0.37
871.2 0.9
17.6 0.9
36
58.0
73.1
1
5
174.2
14.5
0.15
871.2 0.9
7.1 o.a
15
58
64.3
0.5
3
290.4
12.1
0.12
871.2 0.9
5.9 0.9
12
58
63.0
0.27
8
108.9
2.5
0.03
871.2 0.9
1.2 0.8
0
50.0
50.0
'omputed from Woodward-Clyde, 1986
80040000H:\wp\Report\RoadsVappend*a.tbl
A-37
Woodward-Clyde
January 29, 1993
-------
EAST GULF
Mean Coef. of Variation
Volume 0.8 1.19
Intensity 0.178 1.03
Duration 6.4 1.05
Interval 130 1.25
Area= 1 ac
Rv = 0.5
Volume= 90% ave runoff 1307 cf
(0.36 in. runoff) (1 ac * 0.50 * 0.80 in * 90%)
OR
VR
323.07
1452
* * *
~ **
Perc.
Height
Surf. Area
Rate (in/hr)
M
(sq.ft.)
QT
QT/QR
VB
8.27
2
653.4
450.3
1.39
1306.8
2.41
3.2
408.4
82.0
0.25
1306.8
2.41
8
163.4
32.8
0.10
1306.8
1
1.2
1089.0
90.8
0.28
1306.8
1
2
653.4
54.5
0.17
1306.8
1
5
261.4
21.8
0.07
1306.8
0.5
3
435.6
18.2
0.06
1306.8
0.27
8
163.4
3.7
0.01
1306.8
* Fig 4*
~Fig 1*
~Fig
3
R
E
VEA/R
% FLOW
%
VOL
% REMOVA
0.9
40.3
0.9
72
55.0
87.4
0.9
7.3
0.9
23
55.0
65.4
0.9
2.9
0.9
8
55.0
58.6
0.9
8.1
0.9
24
55.0
65.8
0.9
4.9
0.9
18
55.0
63.1
0.9
2.0
0.8
0
50.0
50.0
0.9
1.6
0.8
0
50.0
50.0
0.9
0.3
0.2
0
18.0
18.0
iputed from Woodward-Clyde, 1986
80M0000H:\wp\Reporl\Road3\append-».tbl
Woodward-Clyde
A-38 January 29, 1993
-------
MID-ALTU\NTIC
Mean Coef. of Variation
Volume 0.64 1.01
Intensity 0.092 1.2
Duration 10.1 0.84
Interval 143 0.97
Area =
Rv =
Volume =
1 ac
0.5
90% ave runoff
(0.29 in. runoff)
1 053 cf
(1 ac * 0.50 * 0.64 in * 90%)
Perc.
OR
VR
166.98
1161.6
**~
Height
Surf. Area
(in/hr)
M
(sq. ft.)
QJ
QT/QR
VB
8.27
2
526.4
362.7
2.17
1052.7
8.27
5
210.5
145.1
0.87
1052.7
8.27
8
131.6
90.7
0.54
1052.7
2.41
3.2
329.0
66.1
0.40
1052.7
2.41
8
131.6
26.4
0.16
1052.7
1
1.2
877.3
73.1
0.44
1052.7
1
2
526.4
43.9
0.26
1052.7
1
5
210.5
17.5
0.11
1052.7
0.5
3
350.9
14.6
0.09
1052.7
0.27
2
526.4
11.8
0.07
1052.7
0.27
5
210.5
4.7
0.03
1052.7
0.27'
8
131.6
3.0
0.02
1052.7
VB VB/VR
* Fig 4*
VE/VR
* Fig 1*
% FLOW
* Fig 3
% VOL
% REMOVA L.
0.9
44.7
0.9
81
58.0
92.0
0.9
17.9
0.9
51
58.0
79.4
0.9
11.2
0.9
35
58.0
72.7
0.9
8.1
0.9
30
58.0
70.6
0.9
3.3
0.9
13
58.0
63.5
0.9
9.0
0.9.
33
58.0
71.9
0.9
5.4
0.9
19
58.0
66.0
0.9
2.2
0.9
7
58.0
60.9
0.9
1.8
0.9.
0
58.0
58.0
0.9
1.5
0.8
0
53.0
53.0
0.9
0.6
0.5
0
39.0
39.0
0.9
0.4
0.3
0
25.0
25.0
Computed from Woodward-Clyde, 1986
80040000H:\wp\Rcpoit\Road3\append-a.tbl
A-39
Woodward-Clyde
January' 29, 1993
-------
VEGETATIVE FILTER STRIP REMOVAL EFFICIENCY CHART
Woodward-Clyde
80040000H:\wp\Reporl\Roads\append-a.tbl January 29, 1993
A-40
-------
0.04
0.08
0.12 0.16 0J20
AVERAGE FLOW OEPTH ( FT.)
0.24
0.28
Virginia Channel - Mean Runoff Event
Florida Channel - Mean Runoff Event
Taken from Hartigan et al, 1989
80040000H:\wp\Report\Roads\append-«.thI
A-41
Woodward-Clyde
Jsnuary 29, 1993
-------
\r\(sWrc^rivr*
-------
APPENDIX B
COST DATA
-------
BMP CONSTRUCTIONCOST ESTIMATES
(Cost include construction costs only, exclude land, engineering, etc.)
INFILTRATION BASIN
INFILTRATION BASIN- Washington, D.C. (based on equation from regression analysis from bids for
for 53 ponds and taking out 50% of outlet cost; Wiegand et al, 1986
C=3.05* V" 0.75
Storage
Total
Annual
Volume
Cost
Cost/Cu. Ft.
Maint. Cost
(cu. ft.)
(1988 $)
(S/cu. ft.)
(% capital cost)
10,000
3,146
0.31
3-5%
20,000
5,290
0.26
3-5%
30,000
7,170
0.24
3-5%
40,000
8,897
0.22
3-5%
50,000
10,518
0.21
3-5%
60,000
12,059
0.20
3-5%
70,000
13,537
0.19
3-5%
80,000
14,963
0.19
3-5%
90,000
16,345
0.18
3-5%
100,000
17,689
0.18
3-5%
3te: Cost estimates from Schueler et al, 1985 were not used since
and updates
INFILTRATION BASIN- Oconomowoc, Wisconsin (estimated for 3 foot deep infiltration basin)
Storage Total Annual
Volume Cost Cost/Cu. Ft. Maint. Cost
(cu. ft.) (1988 $) ($/cu. ft.) (% capital cost)
NA NA 1.18 13%
80040000\123\report\roads
B—1
January 29, 1993
-------
INFILTRATION BASINS- Southeastern Wisconsin (estimated from graphs calculated from unit costs); SWRPC, 1991
Storage
Total
Annual
Volume
Cost
Cost/Cu. Ft.
Maint. Cost
(cu. ft.)
(1988 $)
($/cu. ft.)
(% capital cost)
30,000
22,000
0.73
5%
50,000
30,000
0.60
4%
75,000
38,000
0.51
3%
100,000
44,000
0.44
3%
250,000
110,000
0.44
3%
500,000
210,000
0.42
3%
750,000
300,000
0.40
3%
1,000,000
340,000
0.34
3%
80040000\123Veport\roads
B-2
January 29, 1993
-------
CHART 1. UNIT CONSTRUCTION COST AND TOTAL ANNUAL COST OF INFILTRATION BASIN
INFILTRATION BASIN
TOTAL ANNUAL COST/CU FT STORAGE
Siornge. cu.fi.
O
CJ
c
o
o
CJ
c
ZD
0.1 1—
1000
INFILTRATION BASIN
COST/CU FT STORAGE
A A,
10000
100000
Storage, cu. ft.
1000000
lOOOOOn.
80040000\123\report\roads
B-3
January 29, 1993
-------
INFILTRATIONTRENCH
INFILTRATION TRENCH - Washington, D.C. (based on equation from regression analysis from bids for
7 trenches); Wiegand, et.al., 1986
C=26.55*V^ 0.63 V= volume of void space
Storage Total Annual
Volume Cost Cost/Cu. Ft. Maint. Cost
(cu. ft.) (1988 $) ($/cu. ft.) (% capital cost)
300
996
3.32
NA
500
1,373
2.75
NA
750
1,773
2.36
NA
1,000
2,125
2.13
NA
2,000
3,289
1.64
NA
3,000
4,247
1.42
NA
4,000
5,090
1.27
NA
5,000
5,859
1.17
NA
6,000
6,572
1.10
NA
7,000
7,242
1.03
NA
8,000
7,878
0.98
NA
9,000
8,485
0.94
NA
10,000
9,067
0.91
NA
SURFACE INFILTRATION TRENCH- Washington, D.C.; Macal, et.al., 1987
Storage Total Annual
Volume Cost Cost/Cu. Ft. Maint. Cost
(cu. ft.) (1988 $) ($/cu. ft.) (% capital cost)
NA NA NA 5-10%
80040000\123\report\roads B-4 January 29, 1993
-------
UNDERGROUND INFILTRATION TRENCH - Washington, D.C.; Macal, et.al., 1987
Storage Total Annual
Volume Cost Cost/Cu. Ft. Maint. Cost
(cu. ft.) (1988 $) ($/cu. ft.) (% capital cost)
NA NA NA 10-15%
INFILTRATION TRENCH- Wisconsin (estimated from graphs calculated from unit costs, assumed
storage volume equals 40% total volume); SE Wise. Reg. Planning Comm., 1991
Storage
Total
Annual
Volume
Cost
Cost/Cu. Ft.
Maint. Cost
(cu. ft.)
(1988 $)
($/cu. ft.)
(% capital cost)
Comments
198
1,815
9.17
7%
5'x3'x33'
304
1,805
5.94
5%
5'x8'x19'
300
2,750
9.17
7%
5'x3'x50
2004
12,525
6.25
7%
10'x3'x167'
2016
9,450
4.69
5%
io^s^'
3996
21,756
5.44
6%
15'x3'x222'
3984
16,600
4.17
6%
15'x8'x83
9600
40,000
4.17
6%
15'x8'x200'
80040000\123\report\roads
B—5
January 29, 1993
-------
INFILTRATION TRENCH - (based on equation); Kuo, et.al., 1988
cost= 1.28*(0.68*(w*/*(d+1)) + 0.28*((w*l) + (w*d) + (l*w))+2.5*(d+1) + 0.04*((20+w) + (40+0)
Storage Total Annual
Volume Cost Cost/Cu. Ft. Maint. Cost
(cu. ft.) (1988 $) ($/cu. ft.) (% capital cost] Comments
5'x2'x20'
5'x3'x33'
5'x8'x13'
5'x3'x50'
s'xs'xig*
5'x3'x67'
5'x8'x25'
10'x3'x167'
5'x3'x125'
10'x4'x250'
10'x8'x125'
80
364
4.55
NA
198
768
3.88
NA
234
799
3.41
NA
300
1,145
3.82
NA
304
1,013
3.33
NA
402
1,521
3.78
NA
400
1,306
3.27
NA
3,004
6,806
2.27
NA
750
2,805
3.74
NA
4,000
12,844
3.21
NA
4,000
11,879
2.97
NA
80040000\123\report\roads
B-6
January 29, 1993
-------
CHART 2. UNIT CONSTRUCTION COST AND TOTAL ANNUAL COST OF INFILTRATION TRENCH
80040000M 23\report\roads
B—7
January 29, 1993
-------
VEGETATIVE BUFFER STRIP
GRASS BUFFER STRIP- Washington, D.C.; Schueler, 1987
1988
Annual
Establishmen
Area
Cost/ac.
Maint. Cost
Method
(acres)
($/ac.)
(% capital cost)
Hydroseedinc
1-2
2,024
NA
Hydroseedin<
2-5
1,793
NA
Hydroseedin<
5+
1,486
NA
Conventional
1-2
1,845
NA
Conventional
2-5
1,691
NA
Conventional
5+
1,486
NA
Conventional
1-2
8,686
NA
blanket or net
Sodding
1-2
11,171
NA
FOREST BUFFER STRIP- Washington, D.C.; Schueler, 1987
1988 Annual
Cost/acre Maint. Cost
($/ac) (% capital cost)
Conifers- seedlings 102 NA
Deciduous- seedlings 205 NA
Nursery stock-inexpensive species 1,025 NA
Nursery stock-expensive species 5,124 NA
80040000\123\report\roads
B-8
January 29, 1993
-------
MARSH BUFFER STRIP- Washington, D.C.; Schueler, 1987
1988 Annual
Cost/acre Maint. Cost
($/ac.) (% capital cost)
Rhizomes, plugs or small pots 2,050 NA
SOD GRASS FILTER STRIPS- Wisconsin (estimated from graphs calculated from unit costs);
SE Wise. Reg Planning Comm., 1991
Annual
Cost/acre Maint. Cost
($/ac.) 1% capital cost)
40* Wide VFS
27,200
3%
60' Wide VFS
25,400
3%
80' Wide VFS
24,500
3%
100'Wide VFS
25,700
3%
80040000\123\report\roads B-9 January 29, 1993
-------
SWALES
GRASS SWALES- 15 ft wide, 3:1 sideslope (approx. 2.5 ft deep)- Washington, D.C.; Schueler, 1987
1988
Cost/linear ft.
Excavation/shaping plus: ($/linear ft) Comments
Seeding/straw mulching 4.61 more economical
Seeding/net anchoring 8.45 than the curb and
Sodding/stapling 7.94 gutter they replace
SODDED GRASS SWALES- Wisconsin (cost estimated from graph calculated from unit costs);
SE Wise. Reg. Planning Comm., 1991
1988
Cost/linear ft.
($/lin ft)
1' bottom, 1' deep 9
10' bottom, 1' deep 15
1' bottom, 3' deep 20
10' bottom, 3' deep 28
1'bottom, 5'deep 40
10' bottom, 5' deep 50
80040000\123\report\roads
B—10
January 29, 1993
-------
POROUS PAVEMENT
Cost presented are Incremental Costs, ie. cost beyond that required for conventional asphalt pavement
POROUS PAVEMENT - Wisconsin (Based on unit costs); SWRPC, 1991
Incremental Capital Cost/Ac
(Incremental costs, i.e. cost beyond
that required for conventional asphalt
pavement.)
Low
Cost/Ac
$40,051
High
Cost/Ac
$78,288
Moderate Annual
Cost/Ac Maint. Cost
$59,169 $200/ac/yr*
~Incremental O&M costs( includes
vacuum sweeping, high-pressure
jet hosing and inspections)
POROUS PAVEMENT - Washington, D.C. (Based on unit costs); Schueler, 1987
Incremental
Capital Cost/Ac
Low
Cost/Ac
NA
High
Cost/Ac
NA
Moderate
Cost/Ac
$76,916
Annual
Maint. Cost
NA
Comment
Economy of scale not evident
80040000\123\report\roads
B— 11
January 29, 1993
-------
CONCRETE GRID PAVEMENT
Cost presented are Incremental Costs, ie. cost beyond that required for conventional asphalt pavement
CONCRETE GRID PAVEMENT - National Concrete Masonry Association (Based on unit costs)
Low High
Cost/Ac Cost/Ac
Incremental
Capital Cost/Ac
NA
NA
Moderate
Cost/Ac
$65,340
Annual
Maint. Cost
NA
Comment
ave. incremental costs are between
$ 1.00 to $2.00 per sq. ft.
CONCRETE GRID PAVEMENT - Smith, 1981
Incremental
Capital Cost/Ac
Low High
Cost/Ac Cost/Ac
NA
NA
Moderate
Cost/Ac
Annual
Maint. Cost
$43,560 -$1,900*
Comment
ave. incremented costs are about
$ 1.00 per sq. ft.
*there is a net decreased in operation
and management cost for concrete
pavements with life span of 20 years
80040000\123\report\roads
B—12
January 29, 1993
-------
FILTRATION BASINS
SEDIMENTATION/FILTRATION BASINS- Austin, Texas (engineer's estimates); Tull, 1990
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu.Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
f1988)
($/cu.ft.)
($/ac.)
(% capital cost)
1,815
1
13,613
7.50
13,613
NA
1,815
1
19,058
10.50
19,058
NA
3,630
2
16,880
4.65
8,440
NA
3,630
2
19,602
5.40
9,801
NA
9,075
5
25,682
2.83
5,136
NA
18,150
10
38,115
2.10
3,812
NA
27,225
15
46,283
1.70
3,086
NA
36,300
20
54,450
1.50
2,723
NA
54,450
30
70,785
1.30
2,360
NA
80040000\123\report\roads B-13 January 29, 1993
-------
CHART 3. UNIT CONSTRUCTION COST AND TOTAL ANNUAL COST OF FILTRATION BASIN
Storage, cu. ft
80040000\123\report\roads
B—14
January 29, 1993
-------
WATER QUALITY INLETS/CATCH BASINS
3 Chamber Water Quality Inlet (Oil/Grit Separator); Schueler, 1987
Storage Annual
Volume Maint. Cost
(cu.ft.) Cost.S (% capital cost) Comments
NA 7,500 NA ave= $ 7,000 to
$ 8,000
3 Chamber Water Quality Inlet (Oil/Grit Separator) - Montgomery County, Maryland
Storage
Volume
fcu.ft.)
NA
Cost/Acre
$/ac.
17,500
Annual
Maint. Cost
(% capital cost)
NA
Comments
ave= $ 15,000 to
$ 20,000 per acre
Water Quality Inlet (Catch Basin with Sand Filter) - Shaver, 1991
Storage
Volume
(cu.ft.)
NA
1988 Annual
Cost/Acre Maint. Cost
$/ac. (% capital cost)
10,000 NA
Comments
located in 1986,
Maryland
80040000\123\report\roads
B-15
January 29, 1993
-------
Water Quality Inlet (Catch Basin) - Wisconsin, 1991
Storage Annual
Volume Maint. Cost
(cu.ft.) Cost.$ (% capital cost)
NA 3,000 NA
Water Quality Inlet (Catch Basin) - Austin, Texas
Storage Annual
Volume Maint. Cost
(cu.ft.) Cost.S (% capital cost)
NA 1,150 NA
80040000\123\report\roads B-
Comments
None
Comments
ave= $ 900 to
$1,400, cost of
standard inlets
January 29, 1993
-------
DRY PONDS
DRY PONDS
- Chester County, Penn.; APWA Res.
Foundation
Storage
Drainage
Total
Volume
Area
Cost
Cost/Cu. Ft.
(cu. ft.)
(acres)
(1988 $)
(S/cu. ft.)
65,340
19
20,035
0.31
91,480
30
16,695
0.18
222,200
72
26,713
0.12
335,400
35
18,946
0.06
Cost/Acre
Mac.)
1,033
557
370
541
DRY PONDS- Fairfax, Virginia; APWA Res. Foundation
Storage Drainage Total
Volume Area Cost Cost/Cu. Ft. Cost/Acre
(cu. ft.) (acres) (1988 $) ($/cu. ft.) ($/ac.)
6,530 8 12,018 1.84 1448
13,940 36 11,985 0.86 337
15,250 11 7,673 0.50 731
16,120 18 5,031 0.31 287
25,260 1 6 9,412 0.37 592
28,310 1 2 11,847 0.42 982
37,900 227 7,899 0.21 35
48,790 43 12,269 0.25 286
70,570 25 6,855 0.10 278
94,960 55 15,107 0.16 276
104,110 32 6,913 0.07 218
112,820 20 12,142 0.11 611
253,080 94 20,232 0.08 215
382,020 99 50,050 0.13 507
80040000\123\report\roads
B—17
-------
DRY PONDS- Washington, DC (based on WASHCOG NURP equation from regression analysis for
approx. 30 dry ponds) EPA, 1983
C=77.4*V~0.51
Storage
Drainage
Total
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
feu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
1,000
NA
3,217
3.22
NA
5,000
NA
7,311
1.46
NA
7,500
NA
8,991
1.20
NA
10,000
NA
10,411
1.04
NA
25,000
NA
16,613
0.66
NA
50,000
NA
23,658
0.47
NA
75,000
NA
29,093
0.39
NA
100,000
NA
33,691
0.34
NA
250,000
NA
53,760
0.22
NA
500,000
NA
76,557
0.15
NA
750,000
NA
94,143
0.13
NA
1,000,000
NA
109,021
0.11
NA
Annual
Maint. Cost
(% capital cost)
3-5%
3-5%
3-5%
3-5%
3-5%
3-5%
3-5%
3-5%
3-5%
3-5%
3-5%
3-5%
80040000\123\report\roads
B—18
January 29, 1993
-------
CHART 4. UNIT CONSTRUCTIONIST AND TOTAL ANNUAL COST OF DRY POND
1,000
DRY POND
TOTAL ANNUAL COST/CU FT STORAGE
Storage cu.ft.
1,000,000
0.01
100
1000
DRY PONDS
COST/CU FT STORAGE
¦
1
~
¦ Is
¦
" 1
1 ~
\ ¦ ~
L
r
A
• % ^
10000 100000
Storage, cu. ft.
1000000 10000000
80040000\123\report\roads
B—19
January 29, 1993
-------
ALL PONDS >10,000 cu. ft. and < 100,000 cu. ft. - Washington, D.C. (Based on equation from regression analysis
from bids for 53 ponds); Wiegand, et.al., 1986
C = 6.11*V~ 0.752
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
(% capital cost)
10,000
NA
6,419
0.64
NA
5%
20,000
NA
10,810
0.54
NA
5%
30,000
NA
14,663
0.49
NA
5%
40,000
NA
18,205
0.46
NA
5%
50,000
NA
21,531
0.43
NA
5%
60,000
NA
24,695
0.41
NA
5%
70,000
NA
27,730
0.40
NA
5%
80,000
NA
30,659
0.38
NA
5%
90,000
NA
33,498
0.37
NA
5%
100,000
NA
36,260
0.36
NA
5%
MALLONSITE DETENTION PONDS-
- Orlando,
Florida; APWA Res. Foundation
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
(% caDital cost)
18,000
NA
14,400
0.80
NA
NA
160,000
NA
84,800
0.53
NA
NA
250,000
NA
75,000
0.30
NA
NA
500,000
NA
105,000
0.21
NA
NA
1,000,000
NA
140,000
0.14
NA
NA
80040000\123\report\roads
B—20
January 29, 1993
-------
4 DETENTION PONDS AND INTERCONNECTING PIPE - Wisconsin; APWA Res. Foundation
Storage
Volume
(cu. ft.)
392,040
Drainage
Area
(acres)
55
Total
Cost
(1988 $)
158,689
Cost/Cu. Ft.
($/cu. ft.)
0.40
Cost/Acre
($/ac.)
2,885
Annual
Maint. Cost
(% capital cost)
NA
80040000\123\report\roads
B—21
January 29, 1993
-------
WET PONDS
WET PONDS - Chester County, Penn.; APWA Res. Foundation
Storage
Volume
(cu.ft.)
161,170
174,240
1,002,000
Drainage
Area
(acres)
12
275
174
Total
Cost
(1988 $)
8,348
61,339
98,143
Cost/Cu. Ft.
($/cu. ft.)
0.05
0.38
0.56
Cost/Acre
($/ac.)
720
223
564
Annual
Maint. Cost
(% capital cost)
NA
NA
NA
WET PONDS
- Fairfax, Virginia; APWA Res. Foundation
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
(% capital cost)
NA
12
10,201
NA
823
NA
NA
13
4,626
NA
349
NA
NA
17
1,695
NA
102
NA
NA
27
20,677
NA
768
NA
98,880
56
7,371
0.07
132
NA
115,430
57
7,861
0.07
139
NA
NA
105
4,979
NA
47
NA
. 80040000\123\report\roads
B—22
January 29, 1993
-------
ALL PONDS >10,000 cu. ft. and < 100,000 cu. ft.- Washington, D.C. (based on equation from regression analysis
from bids for 53 ponds); Wiegand, et.al., 1986
C=6.11*V~ 0.752
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
1% caoital cost)
10,000
NA
6,419
0.64
NA
NA
20,000
NA
10,810
0.54
NA
NA
30,000
NA
14,663
0.49
NA
NA
40,000
NA
18,205
0.46
NA
NA
50,000
NA
21,531
0.43
NA
NA
60,000
NA
24,695
0.41
NA
NA
70,000
NA
27,730
0.40
NA
NA
80,000
NA
30,659
0.38
NA
NA
90,000
NA
33,498
0.37
NA
NA
100,000
NA
36,260
0.36
NA
NA
80040000\123\report\roads
B—23
January 29, 1993
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WET PONDS > 100,000 cu. ft.- Washington, D.C. (based on equation from regression analysis from bids for 13 wet
ponds.); Wiegand, et.al., 1986
C=33.99*V~ 0.644
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres}
(1988$)
($/cu. ft.)
($/ac.)
(% capital cost)
100,000
NA
58,176
0.58
NA
NA
125,000
NA
67,167
0.54
NA
NA
150,000
NA
75,535
0.50
NA
NA
175,000
NA
83,418
0.48
NA
NA
200,000
NA
90,909
0.45
NA
NA
225,000
NA
98,073
0.44
NA
NA
250,000
NA
104,958
0.42
NA
NA
500,000
NA
164,014
0.33
NA
NA
750,000
NA
212,953
0.28
NA
NA
1,000,000
NA
256,297
0.26
NA
NA
10,000,000
NA
1,129,129
0.11
NA
NA
20,000,000
NA
1,764,440
0.09
NA
NA
30,000,000
NA
2,290,918
0.08
NA
NA
80040000\123\report\roads
B—24
January 29, 1993
-------
WET PONDS - Washington, D.C.; Schueler, 1987
Storage Drainage Total Annual
Volume Area Cost Cost/Cu. Ft. Cost/Acre Maint. Cost
feu, ft.) (acres) (1988 $) ($/cu. ft.) ($/ac.) (% capital cost)
NA NA NA NA NA 3-5%
SMALL ONSITE DETENTION PONDS- Orlando, Florida (in text and estimated off graph); APWA
Res. Foundation
Storage Drainage Total Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
(% capital cost)
18,000
NA
14,400
0.80
NA
NA
160,000
NA
84,800
0.53
NA
NA
250,000
NA
75,000
0.30
NA
NA
500,000
NA
105,000
0.21
NA
NA
1,000,000
NA
140,000
0.14
NA
NA
OFFSITE DETENTION PONDS CREATED FROM NATURAL LOW AREAS- Orlando, Florida; APWA
Res. Foundation
Storage Drainage Total Annual
Maint. Cost
(% capital cost)
NA
NA
NA
NA
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
250,000
NA
40,000
0.16
NA
500,000
NA
55,000
0.11
NA
1,000,000
NA
50,000
0.05
NA
2,000,000
NA
80,000
0.04
NA
80040000\123\report\roads
B—25
January 29, 1993
-------
OFFSITE DETENTION PONDS REQUIRING SUBSTANTIAL EXCAVATION- Orlando, Florida; APWA
Res. Foundation
Storage
Volume
feu, ft.)
500,000
1,000,000
2,000,000
Drainage
Area
(acres)
NA
NA
NA
Total
Cost
(1988 $)
505,000
760,000
1,000,000
Cost/Cu. Ft.
J&SLM
1.01
0.76
0.50
Cost/Acre
($/ac.)
NA
NA
NA
WET PONDS WITH PUMPED REMOVAL - Chicago, III.; APWA Res. Foundation
Storage Drainage
Volume Area
(cu. ft.) (acres)
26,100,000 13,250
Total
Cost Cost/Cu. Ft. Cost/Acre
(1988 $) ($/cu. ft.) ($/ac.)
5,380,346 0.21 406
WET PONDS- Tri-County, Michigan; SE Wise. Reg. Planning Comm., 1991
Storage Drainage
Volume Area
(cu. ft.) (acres)
283,140 NA
Total
Cost Cost/Cu. Ft. Cost/Acre
(1988 $) ($/cu. ft.) ($/ac.)
81,243 0.29 NA
Annual
Maint. Cost
(% capital cost)
NA
NA
NA
Annual
Maint. Cost
(% capital cost)
NA
Annual
Maint. Cost
(% capital cost)
2.5%
WET PONDS- Southeastern Wisconsin; SE Wise. Reg. Planning Comm., 1991
Storage
Volume
(cu. ft.)
43,560
130,680
217,800
435,600
871,200
Drainage
Area
(acres)
NA
NA
NA
NA
NA
Total
Cost
(1988 $)
32,542
61,460
94,022
146,492
227,900
Cost/Cu. Ft.
ft.)
0.75
0.47
0.43
0.34
0.26
Cost/Acre
($/ac)
NA
NA
NA
NA
NA
Annual
Maint. Cost
(% capital cost)
NA
NA
NA
NA
NA
80040000M 23\report\roads
B—26
January 29, 1993
-------
WET PONDS- Southeastern Wisconsin (estimated from graphs calculated from unit costs);
SWRPC, 1991
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
(% capital cost)
30,000
NA
25,000
0.83
NA
5%
50,000
NA
31,000
0.62
NA
4%
75,000
NA
40,000
0.53
NA
4%
100,000
NA
48,000
0.48
NA
4%
250,000
NA
100,000
0.40
NA
3%
500,000
NA
200,000
0.40
NA
3%
1,000,000
NA
330,000
0.33
NA
3%
WET PONDS- Salt Lake County, Utah; SE Wise. Reg. Planning Comm., 1991
Storage
Volume
(cu. ft.)
NA
Drainage
Area
(acres)
160
Total
Cost
(1988
53,068
Cost/Cu. Ft.
ft-)
NA
Cost/Acre
($/ac.)
NA
Annual
Maint. Cost
(% capital cost)
1.5%
WET PONDS- Fresno, California; SE Wise. Reg. Planning Comm., 1991
Storage
Drainage
Total
Annual
Volume
Area
Cost
Cost/Cu. Ft.
Cost/Acre
Maint. Cost
(cu. ft.)
(acres)
(1988 $)
($/cu. ft.)
($/ac.)
(% caDital cost)
NA
NA
1,231,163
NA
NA
0.5%
NA
NA
1,716,868
NA
NA
0.3%
NA
NA
7,207,230
NA
NA
<0.1%
NA
NA
1,201,538
NA
NA
0.9%
NA: Not Available
80040000\123\report\roads
B—27
January 29, 1993
-------
STREET CLEANING - OPERATION COST
includes: wages and salaries, indirect labor, benefits, overhead, fuel, maintenance/materials,
equipment depreciation, and disposal
Location
EPA Region 4
Winston-Salem, NC
EPA Region 5
Milwaukee 1976
Milwaukee 1977
Milwaukee 1978
Milwaukee 1979
Milwaukee 1980
Milwaukee 1988
Milwaukee 1988
Champaigne, IL
EPA Region 9
San Francisco, CA
San Jose, CA
Cost per Curb-Mile
(1989 $'s)
$17.90
$18.07
$17.53
$22.62
$20.61
$19.96
$25.05
$25.00
$14.30-18.00
$12.90-19.40
$27.20
Reference
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
80040000\123\report\roads
B-28
January 29,1993
-------
CHART 5. UNIT CONSTRUCTION COST AND TOTAL ANNUAL COST OF WET / EXTENDED DETENTION WET PONDS
O
oo
o °1
(J
C3
3
C
C
<
o
H
c
D
10.000
WET & ED WET PONDS
TOTAL AN]
NUAL COST/CU F1
rSTORAGE
100,000 1,000,000
Storage, cu.ft.
Z3
o
o
o
c
o
c
o
O
*c
D
0.01
1000
WET PONDS
COST/CU FT STORAGE
10000
100000 1000000
Storage, cu. fL
10000000 100000000
80040000\123\report
B-28A
January 29, 1993
-------
STREET CLEANING - CAPITAL COST
Sweeper Type
Mechanical:
Elgin Pelican
FMC Vanguard 4000
Single broom
Double broom
Vacuum:
Elgin Whirlwind
VAC/ALL Model E-10
Single broom
Double boom
Regenerative Air:
. Elgin Crosswind
FMC Vanguard 3000SP
Single broom
Double broom
TYMCO Model 600
Capital Cost
(1989 $'s)
$65,000 - 75,000
$89,225
$93,550
$120,000
$61,000
$73,467
$110,000
$73,165
$77,700
$87,000
80040000\123\report\roads
B—29
Reference
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
SWRPC, 1991
January 29, 1993
-------
CAPACITIES AND COSTS OF SALT STORAGE BUILDINGS
Storage Building
Int. Dimensions (ft)
Usable
Volume
(yd3)
Capacity
Cost(a) ($)
Cost per ton est.
salt capacity ($)
w
1
hmax
hi
Mass. Turnpike
Wooden Arch
54
78
25
5
1620
1750
35,000
20
Mass. Turnpike
Wooden Rigid Frame
56
77
25
6
1780
1925
50,000
26
California
Dual Storage
50
19
79
50
16
16
7
7
1610
290
1740
310
133,000
65
Maine
Concrete and Wood
28
40
12
4
260
285
6,200
22
North Carolina
Crib with Sliding Roof
18
40
8
8
180
195
7,200
37
N.Y. Thruway
Open Face, Concrete Block
38
27
20
14
310
330
22,000
66
Massachusetts DPW
Braced Timber
36
80
18
8
1175
1270
21,000
17
Domar Dome
51
61
72
82 Diameter
100
116
150
3
3
3
3
3
3
3
360
600
975
1430
2540
3920
8250
390
650
1060
1540
2750
4230
8970
11,000
14,500
18,000
24,000
30,000
42,000
100,000
28
22
17
16
11
10
11
Wheeler Creosoted Timber
28
28
48
39
83
120
16
16
16
14
14
14
430
1150
3020
465
1240
3260
16,000
20,000
36,500
34
16
11
(a) Paving typically not included
80040000\123\report\roads B-30 January 29, 1993
-------
Deicinq Management Practices
Deicing Materials Cost
Usage Ratio
Material
$/ton
to that of Salt
Reference
Sand
$3
Foster, 1990
Salt (NaCI)
$25-50
1
Foster, 1990
NaCI:CaCI @4:1
$75
Land Management Project, 1989
Cargill 90
$150
1
Foster, 1990
GSL Qwiksalt
$150
1
Foster, 1990
Domtar TCI
$150
1
Foster, 1990
Urea
$225
Foster, 1990
Calcium Chloride
$250
CVJ
I
00
o
Foster, 1990
GSL Freezgard
$370
unknown
Foster, 1990
Ethylene glycol
$625
Foster, 1990
CMA
$650
0.6 - 1.2
Foster, 1990
Control Application Cost
Method
Cost
Reference
Spread Rate Control on Trucks
$6,000/truck
Land Management Project, 1989
80040000\123\report\roads B-31 January 29, 1993
-------
The Economic Cost of Road Salt - Results of Six Studies **
(Chevron Chemical Company, 1991)
Study Date
Salt Purchase Price
Vehicle Corrosion
Highway & Bridge Corrosion
Parking Structure Corrosion
Utilities Corrosion
Water Supply Damage
Environmental Damage
Total
Amount of Road Salt Used
U.S. EPA
1976
45
454
113
34
11
660
10,000,000
TISA Study
Salt Inst.
1976
45
145
36
230
10,000,000
Alaska
DOT
1983
$/ton of salt
111
1574
21
1706
4,200
Ontario
Ministry
of Trans.
1985
30
851
94
189
1166
660,000
NY Energy
Develop.
Authority
1987
28
596
738
170
114
1646
1,000,000
Rensselaer
Polytechnic
Institute
1990
50
662
113
71
896
1,000,000
Total Cost in Study Area $6,601,134,216 $2,295,652,174 $7,165,270* $769,773,888 $1,646,168,401 $896,000,000
* Estimated cost if CMA, urea, & sand are used instead = $3,200,000 (Foster et al, 1990)
** All costs in 1990 dollars
80040000\123\report\roads
B—32
January 29, 1993
------- |