EPA/625/R-93/004
                                            September 1993
             Handbook


      Urban Runoff Pollution
Prevention and Control Planning
      U.i Environmental Protection Agency
  Cent
 i'ce of Research and Development
/for Environmental Research Information
      Cincinnati, Ohio
                                  Printed on Recycled Paper

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                                              Notice
This document has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and
administrative review policies and approved for publication. Mention of trade names or commercial products does
not constitute endorsement or recommendation for use.

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                                     Contents
Chapter 1  Introduction.			 1

           Purpose of Handbook	.....	 1
           Target Audience of the Handbook	 2
           Overview of Urban Runoff Pollution	 2
           References	 8

Chapter 2  Regulatory Framework	 9

           Storm Water NPDES Permit Program	 9
           Combined Sewer Overflow Strategy	 10
           Pollution Prevention  Act	(.	 11
           Safe Drinking Water Act	 11
           Nonpoint Source Management Program	 12
           Coastal Zone Nonpoint Source Pollution Control	 12
           Clean Lakes Program	 13
           National Estuary Program	 14
           Agricultural Nonpoint Source Programs	 14
           Summary	,	 15
           References	 15

Chapter 3  The Planning Process	 17

           Description of the Planning Process	 17
           Initiate Program	 20
           Determine Existing Conditions		 21
           Collect and Analyze  Additional Data	 22
   ;        Assess and Rank Problems	 22
           Screen Best Management Practices				 22
           Select Best  Management Practices.	 23
           Implement Plan	 23
           Summary	 23
           Case Study: City of  Lewiston, Maine, CSO, Storm Water, and Nonpoint Source
           Planning Program	 24
           References	 28
                                         iii

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                               Contents (continued)
                                                                                   Page
Chapter 4  Determine Existing Conditions	.	 29

           Preparing a Watershed Description	 29
           Preparing a Receiving-Water Description	 35
           Summary	 39
           Case Study: Cily of Lewiston, Maine, CSO, Storm Water, and NPS Planning
           Program Existing Conditions Assessment	 40
           Case Study: Pipers Creek Watershed Characterization and Water Quality
           Assessment	 47
           References	 51

Chapter 5  Collect and Analyze Additional Data	 53

           Objectives of Data Collection	 53
           Data Collection Programs	'.	 54
           Cost Estimating for Data Collection Programs	 63
           Data Management and Analysis	,	 64
           References	 73

Chapter 6  Assess and Rank Problems	 75

           Problem Assessment Criteria	 75
           Resource Assessments	 84
           Institutional Assessments	 88
           Goals and Objectives Assessments	 88
           Problem Ranking	 88
           Case Study: Ohio Environmental Protection Agency Biological Criteria for the
           Protection of Aquatic Life	 92
           References	 97

Chapter 7  Screen Best Management Practices	  101

           Best Management Practice Overview	  101
           Best Management Practice Screening	  102
           Best Management Practice Descriptions	  107
           Case Study: City of Austin, Texas, Local Watersheds Ordinances	  130
           References 	  134
                                         IV

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                              Contents (continued)
                                                                                  Page
Chapter 8  Select Best Management Practices		  137

           Alternatives Development	  137
           BMP Selection Process	  140
           Conclusions	  147
           Case Study: Maine Department of Environmental Protection
           BMP Selection Matrix		  148
           Case Study: Santa Clara Valley, California, Nonpoint Source Control Program
           BMP Screening Procedure	  151
           References	  156

Chapter 9  Implement Plan.		....	  157

           Contents of an Urban Runoff Pollution Prevention and Control Plan	  157
           Summary	  164
           Case Study: Pipers Creek Watershed Action Plan for the Control of Nonpoint
           Source Pollution		  165
           References	  168

Appendix A Additional References			  169

           Hydrology References	  169
           Water  Resource Sampling References...				  169
           Other Nonpoint Source Pollution References	  169

Appendix B Table of Annotated References	  171
Appendix C Acronyms and Abbreviations			  173

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                                            List of Figures
Figure
Page
 1-1   "typical changes in runoff flow resulting from paved surfaces	 4
 1-2   Pre- and postdevelopment hydraulics	 4
 3-1   Urban runoff pollution prevention and control planning process	 19
 3-2   Watersheds in Lewiston, Maine	 25
 4-1   Total suspended solids (TSS) concentrations	 39
 4-2   Pipers Creek watershed	 48
 5-1   Example stage discharge rating curve.	 63
 5-2   Fecal coliform densities at Station A	.	 66
 5-3   Fecal coliform densities at Station E	 66
 5-4   Relationship between flow and pollutant concentrations	 69
 5-5   Untransformed total suspended solids (TSS) data	 70
 5-6   Log-transformed total suspended solids (TSS) data	 70
 5-7   Distribution of macroinvertebrate indicator species along a sewage leachate-affected stream..... 72
 5-8   Cluster analysis dendrogram for sewage-affected stream survey results	 73
 6-1   Schematic representation of watershed...'.	 90
 6-2   Number of species vs. drainage area for determining 5, 3, and 1  index of biotic
      integrity (IBI) scoring	 94
 6-3   Total taxa vs. drainage area for determining 6, 4, 2, and 0 invertebrate community
      index (IC1) scoring	 96
 7-1   Sample nonstructural control screening matrix	  104
 7-2   Extended detention pond	  112
 7-3   Wet detention system	  114
 7-4   Example shallow-constructed wetland system design for storm water treatment	  115
 7-5   Example wet detention system design for storm water treatment	  115
 7-6   Sample infiltration basin	  117
 7-7   Sample infiltration trench	  118
 7-8   Porous pavement cross section	  119
 7-9   Sample grass-lined swale	  120
 7-10  Schematic design of  a filter strip	  121
 7-11  Conceptual design of a filtration basin	  122
 7-12  Schematic design of  sand filter	  123
 7-13  Conceptual water quality inlet	  125
 7-14  Total suspended solids loading vs. percent impervious cover	  133
 8-1   Example alternative development process	  139
 8-2   Phosphorus removal  for candidate control programs	  140
 8-3   Conceptual diagram of BMP selection method	  141
 8-4   Example continuous simulation results	  142
 8-5   Example cost-benefit ratio curve	  144
 8-6   Santa Clara Valley watershed	  152
8-7   BMP selection process	  154
9-1   Example CSO control conceptual design of a sedimentation/disinfection facility	  158
9-2   Example runoff control conceptual design for a filter system	  158
9-3   Sample agency responsibility matrix	  161
                                                  VI

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                                           List of Tables
Table

 1-1
 1-2
 1-3
 2-1
 3-1
 3-2
 3-3
 3-4
 3-5
 3-6
 4-1
 4-2
 4-3
 4-4
 4-5
 4-6
 4-7
 4-8
 4-9
 4-10
 4-11
 4-12
 4-13
 4-14
 4-15
 4-16
 4-17
 4-18
 5-1
 5-2
 5-3
 5-4
 5-5
 5-6
 5-7
 5-8
 5-9
 5-10
 6-1
 6-2
 6-3
 6-4
 6-5
 6-6
                                                                                       Page
Comparison of Water Quality Planning Projects	
Summary of Urban Runoff Pollutants	... *	
Relative Contribution of Nonpoint Source Loading		....	.........
Estuaries in the National Estuary Program as of 1993.	
Planning Approaches Defined in Regulatory Programs	
Planning Approaches Defined in the Literature	„	
Federal and State Regulation of Urban Runoff	
Land Use Near Major Watersheds in Lewiston, Maine	
City of Lewiston Initial Water Resources Goals				
Comparison of Maine Water Quality Standards	
Use of Mapping Resources for Urban Runoff Planning .•.	
Land Use and Land Cover Classification System.			,	
Federal Sources of Watershed-Related Data	
Federal Sources of Geographic Information  System Mapping Data		
Use of Nonstructural Practices in Study Area Watersheds		
Frequency and Types of Nonstructural Practices Used in Study Area Watersheds	
Existing Regulatory Control Summary—Subdivision Control	
Federal Sources of Water Resource and Hydrology Data	
Example Water Resource Data Spreadsheet	
Lewiston Watershed Data	
Summary of Lewiston Nonstructural Controls—Conservation Districts	
Summary of Lewiston Nonstructural Controls—Performance Standards		
Summary of Lewiston Nonstructural Controls—Development Review Standards	
Existing Source Controls/Municipal BMPs	
Lewiston Existing Structural Controls	
Lewiston Source Input and Receiving-Water Data	
Pipers Creek Watershed Characterization Data		
Pipers Creek Water Quality Characterization Data	
Priority Pollutants in at Least 10 Percent of Nationwide Urban Runoff Program Samples,
Storm Water Sampling Parameters	,
.Detection Frequencies of the Most Frequently Occurring Organic Compounds	...-.,
Typical Combined Work/Quality Assurance Project Plan	
Example Spreadsheet Format for Water Resource Data		
Spreadsheet to Calculate Nitrogen Loads	
Commonly Used Statistical Calculations	
CSO Sampling Results for Total Suspended Solids	
Commonly Used Ecological Diversity Indices	
Diversity Indices for Sewage Leachate-Affected Stream  Samples	,..,..
Criteria for the Assessment of Pollution Problems		
Types  of Activities and Associated Pollutants	
Water Quality Characteristics of Urban Runoff for the NURP Site	
Characteristics of Rainfall, Storm Water, Combined Wastewater, and Treated Effluent ..
Estimated Urban Runoff Loadings Using Constant Concentrations	
Comparison of Urban Runoff Models	
.  3
.  5
.  6
 14
 17
 18
 25
 26
 26
 27
 30
 31
 32
 33
 34
 35
 36
 37
 38
 41
 42
 43
 44
 45
 46
 46
 49
 50
 55
 55
 55
 58
 65
 65
 67
 68
 71
 72
 76
 77
 79
 80
 80
 83
                                                  vii

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                                     List of Tables (continued)
6-7   Comparison of Receiving-Water Models	  87
6-8   Characteristics of the Targeted Areas and Estimated Concentration Loads	  91
6-9   Estimated Total Suspended Solids Loads for Targeted Areas		  91
6-10  Prioritization Analysis for Urban Area Targeting	  91
6-11  Index of Biotic Integrity (IBI) Metrics	  93
6-12  Qualitative Assessment of Index of Biotic Integrity (IBI) Values	  94
6-13  Qualitative Assessment of Modified Index of Well Being (Mlwb) Values	  95
6-14  Qualitative Assessment of Invertebrate Community Index (ICI) Values	  96
6-15  Indices of Biotic Integrity for Two Headwater Stations in Hocking River, Ohio	  97
7-1   Urban Runoff Pollution Control BMPs	  102
7-2   Structural  BMP Initial Screening Criteria	  106
7-3   Maximum  Development Intensity	  131
7-4   Barton Creek Development Requirements	  134
8-1   Sample BMP Selection	  138
8-2   Example Matrix Comparison	  145
8-3   Example CSO Abatement Alternative Matrix Comparison	  146
8-4   Priority Estuary Storm Water Control Matrix	  149
8-5   Nonpriority Estuary Storm Water Control Matrix	  150
8-6   Summary of BMP Treatment Level Codes	  150
9-1   Potential Implementation  Responsibilities	  162
9-2   Pipers Creek Action Plan Recommendations	  167
                                                VIII

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                                 Acknowledgments
This handbook is the product of the efforts of many individuals. Gratitude goes to each person
involved in the preparation and review of the document.

Authors
David Bingham, William Boucher, and Peter Boucher of Metcalf & Eddy, Inc., Wakefield, MA, were
the principal authors of this handbook.

Technical Contributors
The following  individuals provided  invaluable technical assistance during the development of this
handbook:
          Thomas Mumley, San Francisco Bay Regional Water Quality Control Board, Oakland, CA
          Austan Liebrach, City of Austin, Environmental and Conservation Services Department,
          Austin, TX
          Richard Field,  U.S. EPA, Office of Research and Development, Storm and Combined
          Sewer Program, Edison, NJ
          Michael Brown, Doctoral Candidate, Cranfield Institute of Technology, School of Water
          Sciences, Woldingham, Surrey, UK
          William Swietlik, U.S. EPA, Office of Water, Storm Water Section, Washington, DC
          William Tate, U.S. EPA, Office of Water, Storm Water Section, Washington, DC
    •      Richard Gustav, City of Seattle, Engineering Department, Drainage and Wastewater
          Utility, Seattle, WA
          Christopher Branch, City of Lewiston, Department of Public Works, Lewiston, ME
          Steven Johnson, City of Lewiston, Department of Public Works, Lewiston, ME
          Joyce Noel, Maine Department of Environmental Protection, Augusta, ME

Peer Reviewers
The following individuals peer reviewed this handbook:
          Thomas  Davenport, U.S. EPA, Region V, Watershed Management Unit, Chicago, IL
          Eric  Livingston,  Florida  Department  of  Environmental  Regulation,  Stormwater
          Management Section, Tallahassee, FL
          Earl Shaver, Delaware  Department of Natural Resources and  Environmental Control,
          Division of Soil and Water Conservation, Dover, DE

Editorial Reviewers and Document Production
Heidi Schultz, Eastern Research Group, Inc. (ERG), Lexington, MA, provided editorial review and
produced this handbook.
                                          ix

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Technical Direction and Coordination

Daniel Murray, U.S. EPA, Office of Research and Development, Center for Environmental
Research Information, Cincinnati,  OH, coordinated the preparation of this handbook and
provided technical direction throughout its development.

Special Thanks

Lawrence Martin, U.S. EPA, Office of Research and Development, Office of Science, Planning
and Regulatory Evaluation,  Washington, DC, provided support and assistance during the
preparation of this handbook. His efforts were truly appreciated.

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                                             Chapter 1
                                            Introduction
Purpose of Handbook

Urban runoff pollution sources, including storm water,
combined sewer  overflows,  and  diffuse  or nonpoint
sources of water pollution, are formidable obstacles to
achieving water resource goals in many municipalities.
Because these types of  pollution sources  are  best
addressed locally, the U.S.  Environmental  Protection
Agency (EPA) has prepared  this handbook to provide
local officials with a practical planning  approach for
developing and  implementing urban  runoff pollution
prevention and control plans  in urban settings.

This handbook is designed  to serve  as an overall
reference. Other  references and guidance manuals
have addressed specific aspects  of storm water and
urban nonpoint source  (NPS) control, such as  best
management practice (BMP) design (Schueler, 1987;
Tourbier and Westmacott, 1981), monitoring (U.S. EPA,
1988),  and  regulatory compliance (U.S. EPA, 1991,
1992a,b,c).  This  handbook,  however,  presents  a
step-by-step planning approach that municipal officials
can  use  to  develop technically feasible,  targeted,
affordable, and comprehensive urban runoff pollution
prevention and control plans.  Based on information from
numerous  references,  this   handbook  is   both an
information source for urban runoff pollution issues and
a guide to the planning and implementation of effective
pollution prevention measures and controls.  It will also
help municipalities comply with evolving environmental
regulations related to urban  runoff management and
control.

The handbook is divided  into chapters that outline a
step-by-step planning process. The planning process
emphasizes and addresses the following considerations:

• A multitude of  diffuse pollution  sources exist (e.g.,
  combined  sewer overflows (CSOs), storm water, and
  NPS),  and each type of source often  has specific
  regulatory requirements. The planning approach is
  designed  to be flexible enough to address these
  numerous  sources (including  point  sources)  and
  regulations or  to focus  on  specific  sources  or
  regulations.
o While a high level of complexity and uncertainty is
  unavoidable in urban runoff  control planning, this
  handbook is designed to minimize such difficulties by
  identifying a clear series of logical steps for  the
  analysis. These steps are founded on what various
  regulations require, what is described in the technical
  literature, and what is standard practice for planning.
  Each chapter in the handbook describes one of these
  steps.

• Municipalities need a flexible approach based on the
  problems to be solved and available resources. The
  handbook,  therefore, presents a-range of options
  (from simple to complex) for the major steps in the
  planning process.  Examples of  these  options  are
  provided and case study descriptions are included to
  demonstrate their use.
« Numerous  published resources  address  particular
  aspects of or steps in the planning process. Rather
  than repeat this literature, this handbook refers to the
  best sources and shows where and how to apply
  them in the  planning  process.

« It  is  more  cost effective  to  prevent  potential
  urban   runoff  pollution  problems  and  protect
  existing  resources  than  to  implement  pollution
  controls  once a problem exists.  Therefore,  this
  handbook emphasizes pollution prevention and the
  implementation of regulatory controls designed to
  protect existing resources.

This chapter  provides  an  overview of urban runoff
pollution  issues including  types  of pollutants, their
origins and modes of transport, and their effects on
receiving waters. Chapter 2 discusses the  regulatory
framework and the agencies and programs  that  deal
with urban  runoff pollution prevention and control.
Chapter 3 describes the planning process set forth in
this document. It stresses the iterative nature of storm
water and urban NPS pollution prevention and control
planning,  and the  need  to  set goals that can be
reassessed    and   refined   as   efforts   progress.
Subsequent chapters discuss each step in the planning
process for the development of an urban runoff pollution
prevention and  control plan.  The  process includes

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 assessment of existing conditions using available data
 (Chapter 4), collection and analysis  of supplemental
 data (Chapter 5),  problem assessment and  ranking
 (Chapter 6),  screening  (Chapter  7) and selection
 (Chapter 8)  of  pollution  prevention  and  control
 strategies, and definition of the selected plan (Chapter 9).

 Target Audience of the Handbook

 This handbook has been prepared for municipalities
 seeking to comply with evolving Urban runoff regulatory
 requirements and to improve or protect water resources
 and  their uses through  efficient  and cost-effective
 pollution  prevention  and  control   strategies.  The
 information  in this  handbook  is primarily oriented to
 urban and  suburban  communities  with  residential,
 commercial, and industrial areas. Rural communities
 with  extensive  agricultural  areas are not  directly
 addressed, although some techniques discussed in  the
 handbook are applicable. This document can also be
 used by state  agencies, local environmental groups,
 and  other  entities responsible  for or interested in
 protecting water resources. The  handbook can  be a
 resource   to   persons   of  diverse   backgrounds
 implementing an urban runoff  pollution prevention and
 control project.  For example, it  can  be used  by a
 muItMsciplinary team (from city or county governments)
 that  might  include engineers,  biologists,  planners,
 chemists,   political  officials,   environmental   group
 members, and residents, all contributing their expertise
 and resources to the project.

 Overview of Urban Runoff Pollution
 Urban runoff pollution results from numerous sources.
 It is the result of rainfall and snow melt that becomes
 contaminated  as it travels  through the atmosphere,
 along the land surface, and makes its way to a water
 body. Urban runoff can enter a water body from  an
 identifiable point source, such as  a  separate storm
 sewer outfall or a combined sewer overflow. It can also
 flow  directly into  a water body without  an  easily
 identified point of entry. Regardless of the point of entry,
 urban runoff has diffuse origins  and, therefore, is difficult
 to manage and control.

 EPA regulates certain point source discharges of urban
 runoff through  the  National  Pollutant  Discharge
 Elimination System  (NPDES) permit program. NPDES
 permit requirements currently apply  to urban  runoff
 discharges from separate storm sewer systems of many
 large municipalities and  urban  counties  across the
 country; to urban runoff discharged through a combined
sewer overflow; and to urban runoff discharges from
separate storm sewer outfalls  that violate state water
quality standards.

Since urban runoff that enters water bodies from diffuse
or unidentifiable  locations  and  sources can cause
 significant water quality degradation, it certainly should
 be addressed as part of a municipality's overall urban
 runoff pollution prevention and control program.

 To benefit fully from the nation's urban water resources,
 widespread implementation  of urban runoff pollution
 prevention  measures and controls is necessary. Unlike
 point source control, however, institutional frameworks
 and funding sources to deal with urban runoff pollution
 are  usually not well established, especially in smaller
 communities.

 Urban runoff pollution prevention and control programs
 present unique challenges.  Management and control
 programs must often be developed and implemented at
 the municipal level by local officials who  might not be
 familiar  with  the technical  and  regulatory  issues
 surrounding urban runoff pollution. The development of
 an urban runoff pollution prevention and control plan
 typically requires dealing with an extraordinary amount
 of ambiguity. To  illustrate this complexity,  Table 1-1
 compares various types of water resource improvement
 projects. Municipal wastewater treatment projects are
 driven  by   regulations and  the  NPDES  program
 requirements  to  control point  sources with  large,
 typically  end-of-pipe methods (biological or chemical
 wastewater treatment), which generally do not call for
 land use control or involvement of multiple agencies. At
 the  other  end of the  spectrum,  urban  runoff  and
 nonpoint sources  are inherently difficult to address
 because of the large number and types  of  diffuse
 discharges, the quantity and effects of which are difficult
 to  assess. Control   of  such  sources  can require
 structural   BMPs,    stricter   regulations,    more
 comprehensive municipal maintenance  programs,  and
 environmental  education   for   homeowners    and
 businesses. (BMPs  as used in this handbook  can
 indicate any type of pollution control measure, including
 structural,  regulatory,  maintenance,   education,  or
 others.)  A  successful  local  urban  runoff  pollution
 prevention   and  control  program  depends  on  the
 involvement and support of multiple entities including
 federal  agencies,  state agencies, local  government
 departments, watershed protection groups, and private
 citizens.  Each of  these  groups has a stake in  the
 program's   outcome  and   could   have   significant
 resources to contribute.

 The promulgation of EPA's storm water regulations and
 the evolution and strengthening of other p'rograms, such
 as those dealing  with nonpoint source pollution  (see
 Chapter 2), reflect a  trend—municipalities  are  being
 required  to address diffuse  sources  of  pollution to
 greater and greater degrees. These programs typically
 emphasize  management, rather than  treatment, and
 rely  heavily on  local  control measures. Given  the
complexity  of  urban  runoff pollution  control and  the
typical scarcity of resources,  municipal departments

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Table 1-1.  Comparison of Water Quality Planning Projects
Project Type
Regulatory basis



Type and number of
pollutant sources

Reliability of
predicting pollutant
loads and impacts
Type of alternatives

Emphasis on
regulatory/land use
control
Agencies needed for
implementation
Engineering
Facilities
National
Environmental
Policy Act; State
Construction
Grant Program
One or few point
source(s)

High


Engineering

Limited


Few

CSO Facilities
EPA National
Strategy; State
CSO policies


Few to multiple
point sources

High


Engineering
with some BMPs

Limited


Few

Storm Water
Management
Storm Water
Permit Rule, 40
CFR Part 122


Few to multiple
piped and direct
discharges

Moderate


BMPs and
engineering

High


Some

Nonpoint
Source
Control
CWA,
Section 319



Multiple
nonpoint
sources

Low to
moderate

BMPs with
some
engineering
High


Many

Lake
Restoration
CWA,
Section 314



Multiple
: point and
nonpoint
sources
Moderate


BMPs and
, in-lake

High


Some

Watershed
Management
SDWA, Surface
Water Treatment
Rule


Multiple point
and nonpoint
sources

Low to moderate


Engineering,
BMPs, and in-lake

High


Many

 must share responsibilities,  and  state and federal
 agencies,  as well  as local  groups, ideally should
 network and build coalitions. Successful control efforts
 require effective planning and decision-making to make
 the best use of available resources. Identification of
 high-priority  problem  areas  and  development  of
 effective pollution prevention and control strategies are
 critical to a successful program.
 Land development and intensive land use lead directly
 to many of the pollution problems associated with urban
 runoff. These problems can be divided into two basic
 categories: hydrologic impacts and pollution.

 Hydrologic Impacts of Urbanization

 When precipitation contacts the ground surface, it can
 take  several paths. These include  returning  to the
 atmosphere by  evaporation; evapotranspiration,  which
 includes direct evaporation and transpiration from plant
 surfaces; infiltration  into the ground surface; retention
 on the ground surface (ponding); and traveling over the
 ground  surface (runoff).  Altering  the  surface  that
 precipitation contacts alters the fate and transport of the
 runoff.  Urbanization replaces  permeable surfaces with
 impervious surfaces (e.g., rooftops, roads, sidewalks,
 and  parking lots),  which  typically are designed to
 remove rainfall as quickly as possible. As seen in  Figure
 1-1, increasing the proportion of paved areas decreases
 the  infiltration   and  evapotranspiration   paths  of
 precipitation, thus increasing the amount of precipitation
 leaving an area as runoff.
 In addition to magnifying the volume of runoff, urban
 development increases  the  peak  runoff  rate  and
decreases travel time of the runoff. When mechanisms
that  delay  entry of runoff  into receiving waters (i.e.,
vegetation)  are  replaced with systems designed to
remove and convey storm water from the surface, the
storm water's travel time  to the  receiving  waters  is
greatly reduced, as is the  time required to  discharge
the storm  water generated by a storm. Figure 1-2
shows an  urban area's typical predevelopment and
postdevelopment discharge rates over time.

The following changes to hydrology might be expected
for a developing watershed:
•  Increased peak discharges (by a factor of 2 to 5).

•  Increased volume of storm runoff.

•  Decreased time for runoff to reach stream.
•  Increased frequency and severity of flooding.

•  Reduced streamflow during periods of prolonged dry
   weather  (loss of base flow).
•  Greater  runoff and  stream velocity  during  storm
   events.
Each of these hydrologic changes can lead to increased
pollutant transport and loading to receiving waters. As
peak discharge rates  increase, erosion and channel
scouring become greater problems. Eroded  sediments
carry nutrients, metals, and other pollutants. In addition,
increases in runoff volume result in greater discharges
of pollutants. Pollution problems, therefore, multiply with
increased urbanization.
Changes in hydrology affect receiving waters through
channel widening and subsequent streambank erosion

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                   100%  —
                    80% —
                    60% —
                    40% —
                    20% —
                                Natural
                                 cover
10-20%
 paved
35-50%
 paved
75-100%
 paved
                             Legend

                             r".'.!".'.'..'".".'.l  Evapotranspiration

                             I         I  Runoff

                                        Infiltration
 Figure 1-1.  typical changes in runoff flow resulting from paved surfaces (MPCA, 1989).
                                                           Postdevelopment
                                          Time
Figure 1-2.  Pre- and postdevelopment hydraulics (MPCA, 1989).

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and  deposition, increased stream elevation  due  to
greater discharge rates, and  an increased amount of
sedimentary material within a stream due to streambank
erosion. The decrease in the ground surface's infiltration
capacity and loss of buffering  vegetation undermines a
significant mechanism  for pollutant removal,  thereby
increasing  the load  entering  the receiving  waters.
Hydrologic  changes  can  result  in  more  subtle  but
equally important impacts. Removal or  loss of riparian
vegetation due to erosion, for example, can increase
stream temperature as levels of direct sunlight increase,
which  can  in  turn  change the biological  community
structure. With increased sunlight, algae in nutrient-rich
receiving waters grow faster and the dominant species
changes, which  affects  the  composition  of  higher
organisms.  Increased  imperviousness and  loss  of
ground-water  resupply  can  lead  to  more frequent
low-flow conditions  in perennial streams. The effects of
hydrologic  changes  due  to  urbanization therefore
should be  prevented or  mitigated to minimize  urban
runoff pollution.

Further discussion  of urban runoff hydrologic analysis
is presented in Chapter 6. Appendix A lists sources of
                                         additional, more detailed information on the effects of
                                         urbanization on runoff and stream hydrology.

                                         Urban Runoff Pollution

                                         Prevention and control of urban runoff pollution requires
                                         an understanding  of pollutant categories, of the major
                                         urban sources of these pollutants, and of the pollutants'
                                         effects. Table 1-2  lists the primary categories of urban
                                         runoff  pollutants,  pollutants  associated  with  each
                                         category,  typical  urban  runoff pollutant sources, and
                                         potential effects.  Table 1-3  summarizes the  relative
                                         contribution  of predominant  NFS pollution sources to
                                         the degradation of U.S. rivers,  lakes, and estuaries.
                                         Additional pollutant sources  often  included  in these
                                         categories are shown in Table 1-2.  For municipalities,
                                         urban stormrgenerated runoff and construction are the
                                         most  prevalent sources; outlying agricultural activities
                                         also can play a significant role in many urban areas.

                                         The effects of urban  runoff pollutants vary for different
                                         water resource types. A given municipality's pollutants
                                         of concern, therefore,  depend on the types of water
                                         resources in and downstream of the community, and
Table 1-2.  Summary of Urban Runoff Pollutants

Category         Parameters
                                   Possible Sources
                                                                      Effects
Sediments
 Nutrients
 Pathogens
 Organic
 enrichment
 Toxic
 pollutants
Organic and inorganic
  Total suspended solids (TSS)
  Turbidity
  Dissolved solids
Nitrate
Nitrite
Ammonia
Organic nitrogen
Phosphate
Total phosphorus

Total coliforms
Fecal coliforms
Fecal streptococci
Viruses
E. Coli
Enterococcus

Biochemical oxygen demand (BOD)
Chemical oxygen demand (COD)
Total organic carbon (TOC)
Dissolved oxygen

Toxic trace metals
Toxic organics
 Salts
Sodium chloride
Construction sites
Urban/agricultural runoff
CSOs
Landfills, septic fields
Urban/agricultural runoff
Landfills, septic fields
Atmospheric deposition
Erosion
Urban/agricultural runoff
Septic systems
Illicit sanitary connections
CSOs
Boat discharges
Domestic/wild animals

Urban/agricultural runoff
CSOs
Landfills, septic systems


Urban/agricultural runoff
Pesticides/herbicides
Underground storage tanks
Hazardous waste sites
Landfills
Illegal oil disposal
Industrial discharges

Urban runoff
Snowmelt
Turbidity
Habitat alteration
Recreational and aesthetic loss
Contaminant transport
Navigation/hydrology
Bank erosion

Surface waters
  Algal blooms
  Ammonia toxicity
Ground water
  Nitrate toxicity


Ear/intestinal infections
Shellfish bed closure
Recreational/aesthetic loss
Dissolved oxygen depletion
Odors
Fish kills


Bioaccumulation in food chain
organisms and potential toxicity
to humans and other organisms
Vehicular corrosion
Contamination of drinking water
Harmful to salt-intolerant plants

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  Table 1-3.  Relative Contribution of Nonpoint Source Loading
           (U.S. EPA, 1990a)
                               Relative Impacts, %
  Source
                           Rivers    Lakes   Estuaries
Agriculture
Storm sawers/urban runoff*
Hydrotogical modification
Land disposal
Resource extraction
Construction
Silviculture
55.2
12.5
12.9
4.4
13.0
6.3
8.6
58.2
28.0
33.1
26.5
4.2
3.3
0.9
18.6
38.8
4.8
27.4
43.2
12.5
1.6
 ' Includes combined sewer overflows.

 their  desired  uses.  While  conditions are  very site
 specific, the water resources generally most affected by
 certain pollutants are discussed in the following sections.

 Sediments

 Sediment is made up of particulate matter that settles
 and fills in the bottoms of ditches, streams, lakes, rivers,
 and wetlands. Sediment loading occurs primarily from
 soil erosion and runoff from construction sites, urban
 land, agricultural areas, and streambanks. While some
 sedimentation is natural,  construction, farming,  and
 urbanization accelerate the process by increasing the
 rates  of  storm water  runoff,  by  removing  cover
 vegetation, and by changing slopes and affecting soil
 stability.  Increased  runoff  from  developed  areas
 transports  solids  from various  sources,  including
 deposition from erosion,  litter (both manmade  and
 naturally  produced), and road sanding. These solids
 also carry nutrients, metals, and other substances that
 can affect water resources adversely.

 Sedimentation  can   have   substantial   biological,
 chemical,  and  physical effects  in receiving waters.
 Solids  can either  remain  in suspension  and settle
 slowly, or settle quickly to the bottom. Suspended solids
 can make water look cloudy or turbid, diminishing a
 water  body's  aesthetic  and  recreational  qualities.
 Decreased light penetration into the water column due
 to increased turbidity reduces the growth of microscopic
 atgae  and submerged aquatic vegetation. Suspended
 solids  can also threaten the survival of filter-feeding
 organisms   (e.g.,   shellfish   and  small   aquatic
 invertebrates), which  could stop feeding or feed less
 efficiently. Sight-feeding predators (e.g.,  game fish and
 microscopic predatory feeders)  have trouble locating
 prey In turbid waters and, as a result, can suffer from
 Increased stress and decreased survival.

 Deposited sediments that change the physical nature of
the bottom can greatly alter hydrology and habitat and
affect navigation. Sedentary,  bottom-dwelling species
 can be smothered by accumulating sediment, and the
 habitat change can threaten many species that use the
 bottom habitat to feed,  spawn, or live. Depositional
 sediments are also a sink for adsorbed  pollutants,
 such  as nutrients, toxic  metals, and  organics, which
 can affect  both  water-column  and  bottom-dwelling
 organisms. These toxic pollutants can be remobilized if
 sediments are disturbed and can pose a health hazard
 to  humans through  the  consumption  of  fish  and
 shellfish.  Solids  can cause problems  in  either  the
 suspended or the deposited state. While less of an
 issue for  ground water,  solids can affect all surface
 water resource types.

 Nutrients

 Runoff can contain high concentrations of nitrogen and
 phosphorus, the nutrients of primary concern to water
 quality. Nutrients  are associated with  agricultural  and
 urban  runoff,  atmospheric  deposition, leachate  from
 landfills and septic  systems, and erosion.  Nutrient
 additions can cause eutrophication, or over-enrichment,
 of receiving waters, stimulating algal growth. In many
 cases, nutrients  from urban  runoff  originate  from
 chemical fertilizers and thus are in a dissolved  form
 which algae in the receiving waters can  readily utilize.
 Traditionally,   phosphorus    is    considered    the
 growth-limiting nutrient in freshwater  systems, while
 nitrogen   is  considered  growth-limiting  in  marine
 systems. According to research in estuarine systems,
 however, seasonal shifts  can occur between nitrogen
 and phosphorus enhancement of algal growth (D'Elia et
 al., 1986a,b).

 Nutrient enrichment can result in severe  algal blooms,
 either in the water column or in stream and lake beds
 (by attached forms of algae).  Blooms  in the water
 column can occur either as surface scums of blue-green
 algae   (e.g.,  Anacystis   or  Oscillatoria  blooms)  or
 throughout the water column by numerous species of
 floating algae. In all cases, blooms can be transported
 by wind and currents, and are often concentrated along
 the downwind shoreline; these blooms can  cause
 unpleasant odors  and otherwise  detract  from  the
 aesthetic value of the water resource. High densities of
 certain algal species  can  create  taste  and  odor
 problems   in drinking water  from  reservoirs.  Some
 marine  algal  species   potentially   stimulated    by
 eutrophication of coastal waters contain toxins that can
 be harmful to humans  consuming affected fish  or
 shellfish.  In addition  to  increased algal  densities,
 nutrient enrichment can  lead  to  shifts in species
 composition that can  profoundly affect the transfer of
 carbon through the food  web (Sanders  et al., 1987;
 Duguay et  al., 1989).

 One of the most profound effects of eutrophication is
the depletion of dissolved  oxygen in the water column.
                                                    6

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Algal cells from blooms and aquatic plants not utilized
as food by fish or other aquatic species eventually settle
to the bottom sediments. Bacterial decomposition of this
material consumes oxygen and can  lead  to anoxic
conditions  (little  or  no  dissolved acygen)  in the
near-bottom waters. These conditions can persist for
months  during  the summer,  damaging fish  habitat,
creating odors,  and releasing  more nutrients from the
sediments. This phenomenon can occur on a  small
scale, such as in a pond, small lake, or the quiescent
embayments of lakes and rivers used for spawning, or
on a very large scale such as in the Chesapeake Bay.
While mobile organisms, such as many species of fish,
can  frequently  move away  from  oxygen-stressed
waters,  sessile organisms, such as shellfish, or fish
species that require high levels of oxygen, such as trout,
are at much higher  risk. In  highly  nutrient-enriched
waters,   a diurnal  variation  in  dissolved  oxygen
concentration might occur. During daylight hours, algae
produce oxygen through photosynthesis; then at night,
algae consume dissolved oxygen through endogenous
respiration.
Generally, nutrients cause problems that allow for the
development of algal blooms  in slow-moving waters,
such as lakes, coastal areas, large rivers, and wetlands.
Nutrients  are not considered a significant problem in
fast-moving urban streams, except  when such streams
contribute nutrient loading to other  water resources.

Pathogens
Pathogens are bacteria, protozoa, and viruses that can
cause disease  in humans. Although not pathogenic
themselves, the presence of bacteria such as  fecal
coliform or fecal enterococci are used as indicators of
pathogens and of potential risk to human health. While
detecting these indicator organisms in runoff does not
conclusively prove the presence of  pathogens, no more
reliable system has been developed.
According to data from the Nationwide Urban Runoff
 Program (NURP) study (U.S. EPA, 1983), urban runoff
typically contains fecal coliform densities of 10,000 (104)
to 100,000 (105) organisms  per 100 milliliters. While
these high densities  of  indicator organisms  do  not
 necessarily  indicate  the presence  of   pathogens,
 potential  health risks  are associated with primary
 contact recreation, such as swimming; with secondary
 contact   recreation,  such   as  boating;  and  with
 consumption of contaminated fish and shellfish in areas
 affected by urban runoff.
 The primary sources of bacterial  and viral pathogens
 are runoff from livestock in agricultural areas and runoff
 from pet wastes and other contaminants in urban areas
 (ASIWPCA,  1985).  Other sources of these disease-
 causing  ;organisms  include  failed  septic systems,
 landfills,  .bathers,  combined sewer overflows,  and
unauthorized  sanitary  sewer  connections  to storm
drains.
Pathogens generally cause water quality degradation in
slow-moving waterways and water resources used by
humans for primary and secondary contact recreation
or shellfishing. Pathogens are considered pollutants of
concern in drinking-water sources, slow-moving rivers,
lakes, and estuaries. Pathogen-contaminated discharges
to wetlands  or to fast-moving urban  streams are
typically  less of a concern because of  the lack  of
recreational use and fishing in such waters.

Oxygen-Demanding Matter
As microorganisms consume organic matter deposited
in water  bodies  via  storm-water runoff,  oxygen  is
depleted from the water. Organic enrichment can arise
from  agricultural and urban runoff,  combined sewer
overflows (CSOs),  and leachate from septic tanks and
landfills.   A  sudden  release  of oxygen-demanding
substances into a water body during a storm can result
in total  oxygen   depletion and fish  kills.  Organic
enrichment can also have long-term effects on sediment
quality, increasing organic  content and the tendency of
sediments to deplete surface waters and benthos of
oxygen, referred to as sediment oxygen demand (SOD).
The solid and dissolved organic content of water and its
potential  to  deplete  oxygen  is measured  by  its
biochemical oxygen demand (BOD).
Oxygen-demanding matter  is primarily a concern in
water bodies that  support aquatic life, such as rivers,
lakes, and estuaries. While generally a less  important
consideration  for   fast-moving  urban streams and
wetlands, high organic loads have been shown to cause
oxygen depletion in some  urban streams.

Tox'rc Pollutants
Toxic pollutants include metals and organic chemicals.
 Heavy metals in urban runoff result from sources such
 as the breakdown of galvanized and chrome-plated
 products (e.g., trash cans and car bumpers), vehicular
 exhaust residue, and deicing agents. Potential sources
 of toxic  organic pollutants include vehicular residues,
 industrial  areas,  landfills, hazardous waste sites,
 leaking  underground and aboveground  fuel  storage
 tanks, and  fertilizers  and  pesticides. In the NURP
 studies (U.S. EPA, 1983), copper, lead, and  zinc were
 detected in  more than 90 percent of  storm water
 samples from residential,  commercial,  and  light
 industrial sites;  14 toxic organic  compounds  were
 detected in more than 10  percent of samples.
 Potentially toxic compounds in urban runoff pollution
 include  oil  and grease products from vehicles  and
 construction   equipment.  These   products   enter
 waterways in  runoff from  roads, parking lots, service

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 areas, and construction sites, and can be constituents
 of  landfill  leachate.  Such  hydrocarbons frequently
 become  adsorbed  to sediment particles and are
 deposited in bottom sediments. These compounds are
 toxic to aquatic organisms and  can bioaccumulate  in
 fish and shellfish, potentially resulting in toxic effects  to
 humans consuming this tainted  food. Because of the
 potentially acute and chronic effects of toxic pollutants,
 their discharge to all water resource types should be
 limited.

 Sodium and Chloride

 Discharges of  sodium and chloride to surface waters
 result primarily from road salting  during the winter, and
 snowmelt  during   the early spring  thaws.  These
 discharges can affect  the taste of drinking water, can
 harm people who require low sodium diets, and can
 result in corrosion. Also affected are salt-intolerant plant
 species. Sodium and chloride concentrations in runoff
 are typically small enough  to not  cause  serious
 problems in  water resources with continuous flushing
 (e.g.,  in rivers and streams). Sodium and  chloride
 discharges are more  of a concern in drinking-water
 supplies and water resources that are not well flushed
 (e.g., lakes and ground water).
 References

 When an NTIS  number  is cited in a reference, that
 document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650


ASIWPCA. 1985. Association of State and Interstate
  Water Pollution  Control  Administrators. America's
  clean water: the states' nonpoint source assessment.
  Washington, DC.

D'EIia, C.F., J.G. Sanders, and W.R. Boynton. 1986a.
  Nutrient enrichment and phytoplankton dynamics in
  the Patuxent River estuary. Final Report to Maryland
  Office  of  Environmental  Programs.  [UMCEES]
  Chesapeake Biological Laboratory Ref. No. 86-30.

D'EIia, C.F., J.G. Sanders, and W.R. Boynton. 1986b.
  Nutrient enrichment studies in a coastal plain estuary:
  phytoplankton  growth  in  large-scale  continuous
  cultures. Can. J. Fish Aquat. Sci. 43:397-406.
 Duguay,  L, G. Muller-Parker, S. Cibik, J. Love, J.
   Sanders, and D. Capone. 1989. Effects of insolation
   and  nutrient  loading on the response  of  natural
   phytoplankton.  Final   Report  to  the  Maryland
   Department   of   the   Environment.   [UMCEES]
   Chesapeake Biological Laboratory Ref. No. 89-134.

 MPCA. 1989.  Minnesota  Pollution  Control Authority.
   Protecting water  quality  in  urban   areas:  best
   management practices for Minnesota. St.  Paul, MN.

 Sanders,  J.G.,  S.J.  Cibik,  C.F.  D'EIia, and W.R.
   Boynton.  1987. Nutrient enrichment in a coastal plain
   estuary:   changes   in   phytoplankton    species
   composition.  Can. J. Fish. Aquat.  Sci. 44(1):83-90.

 Schueler,  T.R.  1987.  Controlling  urban  runoff: a
   practical  manual for planning and designing  urban
   BMPs.    Metropolitan   Washington    Council   of
   Governments Publication 87703.

 Tourbier,  J.T.,   and   R.   Westmacott.  1981.  Water
   resources protection  technology.  A handbook  of
   measures to  protect  water  resources  in  land
   development. Urban Land Institute, Washington, DC.

 U.S. EPA. 1983. U.S. Environmental Protection Agency.
   Results of the Nationwide Urban Runoff Program, vol.
   1. Final report (NTIS PB84-185552). Washington, DC.

 U.S. EPA. 1988. U.S. Environmental Protection Agency.
   Guide for preparation of quality assurance project plans
   for the National Estuary  Program.  Washington, DC.

 U.S. EPA. 1990. U.S. Environmental Protection Agency.
   National   water quality  inventory—1988  report  to
   Congress. EPA/440/4-90/003. Washington, DC.

 U.S. EPA. 1991. U.S. Environmental Protection Agency.
   Guidance manual for the preparation of part 1 of the
   NPDES  permit  applications  for  discharges  from
   municipal  separate storm sewer systems. EPA/505/
   8-91/003A. Office of Water, Washington, DC.

 U.S.  EPA.  1992a.  U.S.   Environmental  Protection
   Agency.  Storm water  management  for  industrial
   activities:  developing pollution prevention plans and
   best  management  practices.  ERA/832/R-92/006.
   Office of Water, Washington, DC.

U.S.  EPA.  1992b. U.S.   Environmental  Protection
  Agency. Storm water management for construction
  activities: developing pollution prevention plans and
  best  management  practices.  EPA/832/R-92/005.
  Office of Water, Washington, DC.

U.S.  EPA.  1992c.  U.S.   Environmental Protection
  Agency.  Guidance manual for the preparation of part
  2 of the NPDES permit applications for discharges
  from  municipal separate storm  sewer  systems.
  EPA/833/B-92/002. Washington, DC.

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                                             Chapter 2
                                     Regulatory Framework
The structure of urban runoff regulations includes all
levels of government. Responsibility for enforcement
and oversight of these regulations can  be held by
federal, state, local, or in some cases regional agencies.
Despite this array of  programs and regulations, the
primary responsibility  for  developing  approaches to
solve urban runoff pollution problems generally resides
with  municipalities.  Such  pollution  problems  are
considered to be best handled locally because of the
site-specific nature of pollution sources and of potential
pollution prevention and control activities.
The major direction for prevention and control of urban
runoff pollution has come from the federal government
through the 1972 Clean  Water Act  (CWA)  and its
amendments. Several sections of the Act  deal  with
diffuse source pollution. Additional federal statutes that
address urban  runoff pollution include  the  Pollution
Preventiori Act, the Safe Drinking Water Act (SDWA),
and the Coastal Zone Management Act (CZMA).
This chapter  discusses the major federal regulations,
policies, and programs related to urban runoff pollution
prevention and control. Given the national scope of this
handbook and the site-specific nature of state, regional,
and  local  regulations,  this  chapter  focuses  on
regulations and programs at the federal level. Currently,
the major federal statutes,  regulations, and programs
that provide a framework  for storm water runoff and
NPS pollution prevention and control are:
• Storm Water NPDES Permit Program

• Combined Sewer Overflow Strategy
• Pollution Prevention Act

• Safe Drinking Water Act
• Nonpoint Source Management Program

• Coastal Zone Nonpoint Source Pollution Control

• Clean Lakes Program

• National Estuary Program
• Agricultural Nonpoint Source Programs
This chapter  includes a general discussion of each of
these statutes, regulations, and programs and of how
they relate to urban  runoff pollution control at the
municipal  level.  Because of the dynamic,  evolving
nature of  most of these regulations  and programs,
municipalities  must  keep  up  to  date  on  specific
schedules and requirements. In addition, local officials
need to be familiar with urban runoff pollution prevention
and control programs initiated and overseen by state,
county, and local entities. These programs might stem
from  federal  regulatory authority but  will  be  more
tailored and  directly applicable  to  local issues and
needs.

Storm Water NPDES Permit Program

Under Section 402 of the  1972 CWA, point source
discharges of  pollutants  to navigable  waters are
prohibited unless authorized by an NPDES permit.
Initially, the focus of the permit program was on point
source  discharges  of  industrial   and.  municipal
wastewaters.  As controls for point source discharges
were implemented, however, it became apparent that to
achieve the  water quality  goals of the  CWA,  more
diffuse  sources  of pollutants,  including urban  and
agricultural runoff, also would have to be addressed.
In the  1987 amendments  to  the  CWA, Congress
introduced new provisions  and reauthorized existing
programs   that   address   diffuse   sources.   The
development  of a workable  program to regulate storm
water discharges was challenging given the number of
individual discharges, the diffuse nature of the sources
and related water quality effects, and limited state and
federal  resources. After  extended development and
review,  EPA  promulgated  the  NPDES storm  water
regulations in  November  1990. These regulations
represent the most comprehensive program to date for
controlling  urban and  industrial storm water  runoff
pollution.  The  storm  water   regulations  apply to
municipal  separate storm sewer systems that  serve
either incorporated populations greater than 100,000 or
unincorporated,  urbanized  populations greater than
100,000 based  on the  1980  decennial census. In
addition, EPA defined a discharge associated with
industrial activity;  activities that fall within 11 industrial
categories are required to obtain a NPDES storm water
permit (U.S. EPA, 1990a).

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 The  1990  NPDES  storm water  permit  regulations
 directly affect approximately 200 municipalities and 47
 counties across the  country, as well as an estimated
 125,000  industries  and  10,000  construction  sites
 annually.  Under this extensive  program,  affected
 municipalities and industries must conduct storm water
 runoff  sampling and  collect  site  characterization
 information for each  permit application. The municipal
 permit application requirements include:
 • Proof of the municipality's legal authority to enforce
   the regulations.

 * Characterization of the municipality's storm  water
   runoff through wet-weather sampling.
 • Location  of   illicit  storm drain  connections and
   development   of   a   plan    to  eliminate   those
   connections.

 • Description of existing urban runoff control programs
   and  development  of  a proposed  storm  water
   management program.
 • Analysis of the municipality's fiscal  resources to
   Implement the program.
 Once a permit application is filed and a permit issued,
 both  municipalities  and  industries are  required  to
 comply with permit conditions  as specified  by EPA or
 the responsible state permitting authority. EPA has
 developed general permits designed  to cover  many
 industrial  storm  water  discharges.  These  general
 permits require  the  elimination of non-storm  water
 discharges   from   drainage    systems   and   the
 development of a storm water pollution prevention plan,
 including:
 * Development of a pollution prevention team.
 • Description of sources expected to add pollution to
   runoff.
 • Implementation of source control practices, such as:
   - good housekeeping,
   — preventive maintenance,
   — spill prevention and response procedures,
   — equipment inspections,
   — employee training,
   - recording and internal reporting procedures,
  — removal  of non-storm water discharges,
  — sediment and erosion control, and
  - management of runoff.
 •  Implementation of annual site-compliance evaluations.
 Most   municipalities   in   the   United  States  have
 populations  under 100,000 and  therefore are  not
currently required to file municipal storm water permit
applications. EPA is considering regulations to address
storm water runoff pollution from smaller communities
(CWA Section 402), which could be required to develop
storm water  management plans.  In addition, existing
NPDES regulations allow EPA or a responsible state
permitting authority to require permits for any storm
water discharges that cause violations of water quality
standards.

Combined Sewer Overflow Strategy

Combined sewer overflows (CSOs) are discharges from
sewer systems that are designed to carry storm water
rainfall  and  snowmelt  runoff, along  with  sanitary
sewage, pretreated industrial wastewater, and a certain
quantity of flow from storm and ground-water infiltration.
Combined systems  were constructed  in more than
1,200  municipalities  throughout  the  United States,
particularly  in  the  Northeast,  East,  and   Midwest.
Combined sewer  systems  have   overflow  points
designed  to discharge wet-weather flows tfiat exceed
the carrying capacity of the system (usually designed to
carry peak dry-weather flow).  Such combined sewer
discharges,   if  not treated  before overflowing  into
receiving  waters,  can   significantly  affect  water
resources and threaten human health.

Many municipalities have  begun to  address these
pollution sources  through  various  means,  such  as
storing  and  treating the  discharges, implementing
low-cost BMPs, and replacing combined  sewers with
separate sanitary and storm sewer  systems. Separating
combined systems  can be  a  long  and   relatively
expensive process and  results in a separate storm
drainage  system  that could  eventually require  an
NPDES permit.

To address CSO discharges, EPA developed a national
strategy (Federal Register, 1989), which sets forth three
major objectives in NPDES permitting for CSOs:

• To ensure  that no CSOs occur during  dry-weather
  flow conditions.

• To bring all wet-weather CSOs into compliance with
  the technology-based requirements of the CWA and
  applicable state water quality standards.

• To minimize impacts on water quality, aquatic biota,
  and  human  health  from wet-weather generated
  overflows.

To achieve these objectives, recommended strategies
include the application of the best conventional pollutant
control technology  (BCT), or best available technology
economically  achievable  (BAT),  based  on  best
professional judgment (BPJ).

The technology-based effluent limitation for CSOs were
mandated to include six minimum technologies:

• Proper operation and maintenance
                                                  10

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• Maximization of collection system storage

• Pretreatment

• Maximization of flow to treatment plant

• Elimination of dry-weather overflows

• Control of solids and floatables
Following the development of a guidance document for
implementing the National CSO Strategy, three more
minimum technologies were added to the list:

• CSO inspection, monitoring, and reporting

• Pollution prevention

• Public notification of CSO impacts
EPA, with input from  numerous state,  municipal,  and
environmental organizations, released a new Draft CSO
Control Policy on January 19,1993. The final policy will
provide   guidance to   permittees  on  developing
consistent  CSO  control strategies,  and to  NPDES
permitting authorities  on developing permit language
and enforcement strategies that will ensure consistent
implementation of control strategies.

Pollution Prevention Act
With the passage of  the Pollution Prevention Act of
1990, Congress  established  a  national policy  that
emphasizes  pollution  prevention over control  or
treatment. With this policy, Congress defined a pollution
prevention  hierarchy  for  all  pollution  reduction
programs:
• Pollution  should be  prevented or  reduced at the
  source whenever feasible.
• Pollution  that   cannot  be   prevented should  be
  recycled in an environmentally safe manner.
• Pollution that cannot be prevented or recycled should
  be treated in an environmentally safe manner.
• Disposal or other release to the environment should
  be  a last resort and should be conducted in an
  environmentally safe manner.
As stated in Chapter 1, one goal of this handbook is to
integrate pollution prevention into urban runoff pollution
control  planning.  Summarizing  the goals of EPA's
pollution prevention program,  the National  Pollution
Prevention Strategy serves two basic purposes:
• To provide guidance  and direction for incorporating
  pollution   prevention   in   EPA  regulatory   and
  nonregulatory programs.
• To  set forth a program  that  will achieve  specific
  pollution prevention objectives in a reasonable  time
  period.
To address the first  objective,  EPA is  investigating
changes  to  the  institutional  barriers  to  pollution
prevention within the Agency by:

• Designating   special   assistants   for  pollution
  prevention  in each assistant administrator's office,

• Developing incentives and awards for Agency staff
  who engage in pollution prevention efforts.

• Incorporating prevention  into each program office's
  comprehensive 4-year strategic plans.

• Providing pollution prevention training to Agency staff.

• Supporting technology innovation.

• Including prevention-related activities in the Agency's
  operating guidance, accountability measures,  and
  regulatory review and development process.

To  address  the second objective,  EPA is targeting
high-risk chemicals and seeking to reduce releases of
these chemicals through a voluntary program.

This   pollution   prevention   policy  was  originally
developed to address industrial waste issues.  Since it
also applies to storm water and diffuse source pollution,
EPA is now  emphasizing  pollution prevention at  the
municipal level in dealing with urban runoff pollution.
Municipalities are encouraged to employ techniques
and policies that reduce  the amount  of pollutants
available for transport in urban runoff. Municipalities can
implement activities and  use management practices
that are  consistent with  EPA's  pollution prevention
policies.  Such  activities  include  public education;
household hazardous waste collection;  location  and
elimination  of  illicit connections  to separate storm
systems; reduction of roadway sanding and salting; and
reduction of pesticide, herbicide, and fertilizer use. Such
programs, which are  discussed  in later chapters, can
reduce the availability of pollutants for washoff.

Safe Drinking Water Act
The Surface Water Treatment  Rule (SWTR) of  the
SDWA outlines requirements for watershed protection.
Municipalities that use surface water for drinking-water
supplies  are required by EPA or the  approved state
agency to develop a watershed protection plan for such
surface  waters  (AWWA,  1990).  Municipalities  are
required to:
• Develop a watershed description, including:
   - the watershed's geographic location and  physical
     features;
   - the  location  of major components of the water
     system  in  the watershed;
   - annual   precipitation   patterns,   streamflow
     characteristics, and other hydrology information;
                                                   11

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   - agreements  and  delineation  of land use and
     ownership.

 • Identify the watershed characteristics and activities
   detrimental to water quality, such as:
   - the effects of precipitation, terrain, soil types, and
     land cover;
   — the effects of animal population;
   - point sources of contamination;
   - nonpoint sources of contamination, such as road
     construction, pesticides, logging, grazing animals,
     and recreational activities.
 • Control  detrimental  activities  by  implementing
   appropriate control practices.
 • Conduct ongoing routine and specific monitoring.
 Under the SDWA, watershed control programs also
 must:

 • Minimize potential contamination by Giardia  cysts
   and viruses in the water source.
 • Characterize the watershed hydrology  and  land
   ownership.

 • Identify watershed characteristics and activities that
   threaten or harm source water quality.
 * Monitor activities that threaten or harm source water
   quality.
 These watershed control programs are designed to
 protect  surface drinking water supplies  from  urban
 runoff and NPS pollutants, and to reduce the need for
 subsequent water treatment.

 Nonpoint Source Management Program
 A 1975 federal program designed  to address  NPS
 pollution,  called  the 208  program, did  not lead  to
 significant implementation. A more recent program,
 initiated under the 1987 CWA amendments, is one of
 the few federal programs that specifically addresses
 and provides funding  for NPS  control. Through this
 program under CWA Section 319, states must submit a
 Nonpoint Source Assessment Report which:
 • Identifies  navigable   waters  that do   not   meet
  applicable water quality standards.
 • Identifies categories of nonpoint sources that add
  significant pollution to the waters not meeting water
  quality standards.
• Describes  the  process for  identifying  BMPs  to
  address the identified nonpoint sources.
• Identifies and describes state programs for controlling
  pollution from identified nonpoint sources.
 To be eligible for funding under CWA Section 319, states
 can use the information in Nonpoint Source Assessment
 Reports to develop and gain EPA approval for Nonpoint
 Source Management Plans. These management plans
 provide a framework to address the state's NPS control
 issues and to  develop priorities  for implementation. At
 a minimum, management plans  must include:

 • An identification of the BMPs selected to address the
   nonpoint sources identified in the Assessment Report.

 • An identification of the programs to implement these
   BMPs.

 • A schedule  with annual  milestones for  program
   implementation.

 • A certification of existing adequate legal authority to
   implement the program.

 • A description of available federal  and state funding
   sources to be used.

 Through CWA Section 319, EPA has the authority to
 base annual NPS funding on its review and approval of
 these management plans. EPA usually grants funds to
 the state authority overseeing NPS control and allows
 the state  authority to earmark the funds for specific
 programs, which are to be implemented on a watershed
 basis to the maximum extent possible. The priorities set
 in a state's management plan influence  how the funds
 will be spent each year. Depending on the state, funding
 through  this  program  could  be  available  for  a
 municipality, or a group of municipalities, to implement
 aspects  of an  NPS  management program  in  a
 high-priority watershed. Funds  from   this  program,
 however,  are  limited  and are  available mainly  for
 demonstration  projects to educate  or  establish  the
 effectiveness of particular controls.

 Coastal Zone Nonpoint Source Pollution
 Control

 Under Section 6217(g) of the 1990 Coastal Zone Act
 Reauthorization,  states with  existing  coastal  zone
 management programs are required to establish coastal
 NPS programs approved by  EPA and the National
 Oceanic and  Atmospheric  Administration  (NOAA).
 These programs will be incorporated into the existing
 state NPS management plans (CWA Section 319) and
 state  Coastal  Zone Management Programs (CZMA
 Section  306). The purpose of Section  6217(g) is to
 encourage states to work with  local authorities and
 other states to develop and implement  a program of
 NPS pollution  management  to  restore and protect
coastal waters (U.S. EPA, 1991). This program is limited
to NPS pollution control in  coastal areas and  the
contribution of inland sources of  pollution to degraded
coastal water quality. In order to maintain a federally
                                                 12

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approved coastal zone program,  states must  act to
reduce NFS pollution through:

• Implementing  EPA-specified management  measures
  and additional state-developed measures  to control
  NPS pollution in  impaired  or  threatened  coastal
  waters.

• Modifying the  state  coastal  zone  boundary,  if
  necessary.

• Developing enforceable policies and mechanisms to
  implement the  Coastal  Zone Act Reauthorization
  management measures.

• Coordinating activities with existing CWA  programs,
  such as basin planning (Section 303), NPS planning
  (Section  319), and the  National  Estuary Program
  (Section 320).

• Developing a technical assistance program for local
  governments  and the  public  to  implement the
  management measures.

• Developing a public participation program.

The  coastal   NPS  program  can  directly  affect
municipalities  in  coastal   areas with  impaired or
threatened waters if they are not covered by the NPDES
municipal permit program (CWA Section 402). They will
likely be required  by the  state coastal NPS  control
agency to implement management practices to address
NPS pollution. In addition,  since this program includes
a requirement for states to reassess  their coastal zone
boundaries, municipalities that formerly were not within
coastal areas might now be included.
EPA and  NOAA, along with  other  federal  and state
agencies,  are  developing  guidance  materials:  a
document to assist states in  developing their coastal
NPS pollution control program (U.S.  EPA, 1991) and a
document   specifying  management   measures  for
controlling  NPS pollution in coastal  areas (U.S. EPA,
1993). This management measures guidance document
includes the following information for each management
measure discussed:

• A description of  activity categories and  applicable
  locations.

• A listing of the pollutants addressed.

• A  description  of  the  water  quality  effects  of
  implementation.

• An  outline  of the expected  pollutant  reductions
  achievable.

• A cost description.

• An outline of specific factors to  be considered in
  adapting management measures to specific sites.
The  major  management  measure  categories  are
agriculture, forestry, urban, marinas and recreational
boating,  hydromodification,  shoreline  erosion,  and
wetlands. Where the proposed management measures
do not address pollution problems adequately, states
must  develop additional management  measures  to
prevent and  reduce  nonpoint  sources of pollution.
States  with   existing  coastal  zone   management
programs  will be required to implement management
measures  in  conformity with the  approved  NPS
measures. This requirement could result in additional
urban   runoff   pollution   prevention   and   control
requirements on affected coastal municipalities.

Clean Lakes Program

The Clean Lakes Program, initiated in 1972 under CWA
Section 314, sets goals for defining the  cause and
extent of pollution problems in each state's lakes and
for developing  effective  techniques to restore these
lakes.  Lake protection or restoration projects should
include the  development of watershed assessments
that consider all point and  nonpoint sources affecting
lake quality. Each state is encouraged to organize and
administer its own lakes program and to apply for EPA
grants for lakes projects that  meet state and  EPA
criteria.
A review  of statewide lake quality, to  be  part of the
biennial state Section  305(b) report, must include:
• Identification and classification of all publicly owned
  lakes.                                   '      '
« Description  of  the  procedures,  processes,  and
  methods to control sources of pollution.
• Description of the methods and procedures to restore
  lake quality.
• Description  of  methods and  procedures to control
  high acidity.
« List of  the lakes for  which  uses are known to  be
  impaired.
• Assessment of the water quality status and trends.

Clean Lakes projects are conducted in several phases:
a  diagnostic/feasibility  study,  implementation   of
recommendations,  and  long-term  monitoring.  The
diagnostic section of the study must  consist of the
following information:

« Name, location, and hydrologic characteristics of the
  lake to  be studied.

• Geologic description of the drainage basin.

• Public access to the lake,
• Size and  economic  structure  of  the watershed's
  population.
                                                  13

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 • Summary of historical lake uses.
 • Adverse impacts caused by lake degradation.
 • Water uses of the lake.
 • Point sources of pollution to the lake and abatement
   actions to reduce this pollution.
 * Land uses in the lake watershed.

 • Discussion   and  analysis  of  historical  baseline
   limnological data and 1 year of current limnological
   data as described in 40 CFR Part 35.
 • Identification and discussion of biological resources
   in the  lake.
 The feasibility section should include:
 * Identification and  discussion of  pollution  control
   alternatives.

 • Benefits expected from implementing the project.
 * Long-term  monitoring schedule.
 • Proposed milestone implementation schedule.
 • Description of how nonfederal funds will be obtained
   for the project
 • Relationship between the proposed  lake project and
   other water pollution control initiatives in the area.
 • Summary of public participation in  developing and
   assessing the project.
 * Operation and maintenance plan.
 * Copies of  all  permits  and  impending  permits
   applicable to the project.
 Once a diagnostic/feasibility report has been submitted
 and approved, federal  grants may  be available to
 implement project recommendations.

 National Estuary Program
 With the 1987 passage of CWA amendments  (Section
 320), Congress created the National Estuary Program
 (NEP) to identify nationally significant estuaries, protect
 and improve their water quality, and enhance their living
 resources (U.S. EPA, 1990b). NEP estuary selection is
 based   on   the   estuaries'  potential  to  include
 environments of significant national concern  and the
 demonstrated commitment by involved local parties to
 protect   these  valuable  resources.   Currently,   21
 estuaries are  part of the NEP (see Table 2-1). Common
 problems found in these estuaries include pollution from
agricultural and urban runoff and  waste  disposal
activities, as well as high levels of toxins and pathogens,
excess nutrient loading,  habitat loss, and declining
abundance of living marine resources.
 Table 2-1.  Estuaries in the National Estuary Program
          as of 1993
 Albemarle-Pamlico Sounds, NC

 Buzzards Bay, MA

 Casco Bay, ME

 Chesapeake Bay, MD/PA/VA

 Corpus Christi, TX

 Delaware Bay, DE

 Delaware Inland Bays, DE

 Galveston Bay, TX

 Indian River Lagoon, FL

 Long Island Sound,  CT/NY

 Massachusetts Bay, MA
Narragansett Bay, Rl

New York/New Jersey Harbor,
NY/NJ

Peconic Bay, NY

Puget Sound, WA

San Francisco Bay, CA

San Juan Bay, PR

Santa Monica Bay, CA

Sarasota Bay, FL

Tampa Bay, FL

Tillamook Bay, OR
Once an estuary is accepted into the NEP, EPA formally
convenes a Management Conference of Agency and
local  representatives to  develop a  Comprehensive
Conservation and Management Plan (CCMP) to protect
the estuary. The Management Conference must also
build  support to  carry out the CCMP recommended
actions,  conduct extensive  research, and  implement
projects  to improve  the water quality of the estuary.
These projects  are usually demonstration activities
implemented on a small scale, but can be applicable to
larger areas of an estuary.

The NEP is  not specifically designed to address the
issue of NPS pollution. All 21 estuaries currently in the
program have identified storm water runoff and diffuse
source  pollution  as  problems. Municipalities located
within   an  NEP  estuary's  watershed   might  be
encouraged as part of the CCMP, therefore, to address
diffuse source pollution issues. In  addition, the NEP is
a  potential funding  source for urban runoff  control
projects. Municipalities  in  the watersheds of  major
coastal embayments should be aware of this program
and  understand  the management  structure  and
program objectives of local NEPs.

Agricultural Nonpoint Source Programs

While this handbook focuses primarily on storm water
and NPS pollution issues  in urban watersheds, many
municipalities have outlying agricultural and other areas
that contribute solids, nutrients, pesticides, herbicides,
and pathogenic organisms to urban receiving waters. In
many areas of the country, a basinwide approach must
be taken to correct receiving-water impacts, and the
basin  is likely to contain agricultural activities. The U.S.
Department  of  Agriculture   (USDA)   administers
programs that address agricultural  NPS  problems.
These programs are managed by the Soil Conservation
Service   (SCS)  and  the  Agricultural   Stabilization
and  Conservation Service  (ASCS),  which conduct
                                                  14

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research;  undertake  demonstration projects; develop
technologies;  and  provide  education,  technical
assistance, and funding (Margheim, 1990).

USDA programs do not set specific regulatory controls
on agricultural practices to  prevent or reduce diffuse
source  pollution.  Rather,   they  provide  technical
assistance and cost-sharing-based funding to farmers
for implementing  agricultural  BMPs,  such as animal
waste control systems, conservation tillage, vegetative
buffer strips, and filter  strips. Also, informational and
educational  services are  provided   through  these
programs by the Cooperative Extension Service.
Examples of USDA pollution control activities include:
• Conservation operations: Provides basic funding for
  technical assistance  to farmers, other  landowners,
  and units of government.

• Small   watershed  projects:.  Provides  planning,
  technical, and financial assistance for implementation
  of  BMPs in small watersheds.
• Resource conservation and development projects:
  Provides  funding  for  personnel  to  coordinate
  interorganizational  cooperation and coordination on
  certain  environmental  activities   in  designated
  multicounty areas.
• Hydrologic unit areas: Provides technical assistance
  to  targeted agricultural watersheds to improve and
  protect water quality.
• Demonstration projects: Provides funding for planning,
  educational, technical, and  financial assistance in
  agricultural  watersheds   for  demonstrating   and
  accelerating the adoption and implementation of new
  and innovative technologies that emphasize protecting
  ground water from  agrichemicals.
• Agricultural conservation program: Shares  cost of
  implementing  agricultural  conservation  practices
  (BMPs) on farmland
• Special projects: Shares cost of implementing water
  quality BMPs in identified watersheds.
• Other: Accelerate  technical assistance to regional
  projects such as National Estuary Programs; develop
  and transfer water quality technology, training, and
  public involvement; promote many  locally oriented
  and organized water quality projects (e.g., Lakes Lay
  Monitoring  Program,  educational  programs  for
  schools, conferences on wetlands and sludge, and
  certification programs for pesticide use).

Summary
As demonstrated in this chapter, numerous regulations
address urban runoff pollution prevention and control at
the federal, state,  and local  levels.  In planning a
program,   all   applicable  regulations   should  be
considered and integrated. For example, the planning
process outlined  in this handbook can  be used  to
develop plans to address pollution from separated or
combined  systems,  or where both systems exist. The
process applies to  BMP programs  both  for  CSO
problems  and  for  separate  storm water;   in  many
instances,  both  sources  exist  within the   same
watershed. It can  also  be  used in multijurisdictional
planning   efforts   where    storm   water,    CSO,
drinking-water  protection,  or  other  elements  are
controlled  by different levels of state, regional, or local
government.

References

When an  NTIS number is  cited in a reference, that
document is available from:
  National Technical Information Service
  5285  Port Royal Road
  Springfield, VA  22161
  703-487-4650

AWWA. 1990.  American Water Works  Association.
  Guidance manual for compliance with the filtration
  and   disinfection  requirements  for  public  water
  systems  using   surface  water  sources.   (NTIS
  PB90-148016). Washington, DC.

Federal  Register. 1989. Fed. Reg. 54(173). Septembers.

Margheim, G.A. 1990. Making nonpoint pollution control
  programs  work,   proceedings   of   a    national
  conference, April  23-26, 1989. National Association
  of Conservation Districts. St. Louis, MO.

U.S.  EPA.  1990a.  U.S.  Environmental  Protection
  Agency. NPDES permit application  requirements for
  storm water discharges. Final regulation: a summary.
  October 31.

U.S.  EPA.  1990b.  U.S.  Environmental  Protection
  Agency. Progress in the National Estuary  Program,
  report to Congress.  EPA/503/9-90/005.  Office  of
  Water, Washington, DC.

U.S. EPA. 1991. U.S. Environmental Protection Agency.
  Coastal Nonpoint Pollution Control Program: program
  development and approval guidance. Office of Water,
  Washington, DC.

U.S. EPA. 1993. U.S. Environmental Protection Agency.
  Guidance  specifying  management  measures  for
  sources  of  nonpoint  pollution  in  coastal waters.
  EPA/840/B-92/002. Office of Water, Washington, DC.
                                                  15

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                                             Chapter 3
                                     The Planning Process
This chapter outlines the process for developing and
initiating urban runoff pollution prevention and control
plans.  It  also  discusses  the   establishment  and
refinement of program goals. Each step in the planning
process  is  discussed  separately and  in  detail  in
subsequent chapters.

Description of the Planning Process

The planning  process  for  urban  runoff pollution
prevention  and  control  programs  presented  in this
handbook is based on regulations that  require such
programs and on technical  literature about planning
approaches. Table 3-1 compares  planning approaches
required by various regulations. Despite the increasing
complexities and uncertainties as one proceeds from
left to right in the matrix (as was demonstrated in Table
1-1), the required planning approaches are similar. The
process  generally consists  of the  following  major
components:

• Determining existing conditions: Analyzing existing
  watershed and water resource data and collecting
  additional data to fill gaps in existing knowledge.

• Quantifying pollution sources and effects: Utilizing
  assessment tools and models to determine source
  flows and contaminant loads, extent of impacfs, and
  level of control needed.

• Assessing alternatives: Determining the optimum mix
  of prevention and treatment practices to address the
  problems of concern.

• Developing  and implementing  the recommended
  plan: Defining the selected system of prevention and
  treatment practices  for  addressing  the  pollution
  problems of  concern and developing a  plan for
  implementing those practices.
Table 3-1.  Planning Approaches Defined in Regulatory Programs
Project Type
Regulatory basis


Determining
existing conditions



Quantifying
pollution sources
and water
resource impacts

Assessing
alternatives



Developing and
implementing the
recommended plan




Engineering
Facilities
National
Environmental
Policy Act
Describe existing
system

Develop planning
criteria
Collect and
analyze data



Develop
alternatives

Assess
alternatives
Develop
recommended
plan

Develop
implementation
plan
CSO Facilities
National CSO
Strategy (8/89)

Describe existing
conditions



Collect and
analyze data



Develop
alternatives

Assess
alternatives
Develop
recommended
plan

Develop
implementation
plan
Storm Water
Management
Storm Water
Permit Rule, 40
CFR 122
Describe existing
conditions



Collect and
analyze data



Developing
alternatives

Assess
alternatives
Develop
management plan

Develop
implementation
plan

Nonpoint
Source Control
CWA, Section
319

Analyze existing
conditions



Collect and
analyze data

Identify and rank
problems
Screen BMPs

Select BMPs


Develop ~
recommended
plan

Develop
implementation
plan
Lake Restoration
CWA, Section
314

Describe
environmental
conditions


Conduct
diagnostic survey



Conduct
feasibility study



Develop
recommended
plan

Develop
implementation
plan
Watershed
Management
SDWA


Develop
watershed
description


Identify
detrimental
characteristics


Conduct risk
assessment



Develop
detrimental
activities control
plan



                                                  17

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Each  regulatory  program  outlined  in  Table  3-1
addresses the  same components  of water  quality
planning but uses different language to describe the
process of each component

For  example, as a result of the differing  regulatory
approaches,    municipalities   might   independently
conduct CSO and storm water planning. Yet since these
sources of pollution often exist in the same watersheds
and  affect the same water  resources, this fractured
approach is  not desirable. To address urban  runoff
pollution  control effectively, communities must consider
multiple pollution sources in planning using a watershed
approach. Table 3-2 lists selected planning  processes
outlined in the literature, which tend to resemble those
required by the regulations  cited in Table 3-1. The
planning process described in this handbook has been
developed to be consistent with regulatory requirements
as well as technical literature.

The planning  approach  used in this handbook  (see
Figure 3-1) is intended  to offer municipal officials a
systematic approach to  developing an  urban runoff
pollution prevention  and  control plan. In general, the
planning process proceeds as follows:

1. Initiate program (Chapter 3)

2. Determine existing conditions (Chapter 4)

3. Set site-specific goals
Tablo 3-2. Planning Approaches Defined in the Literature




Literature
Reference
Determining
existing conditions









Quantifying
pollution sources
and effects



Assessing
alternates








Urban Surface
Water
Management
(Walesh, 1989)
Establish
objectives and
standards

Conduct Inventory






Analyze data and
prepare forecasts




Formulate
alternatives

Compare
alternatives and
select
recommended
plan



Developing the
Watershed Plan
(U.S. EPA, 1991a)
Identify problems
and opportunities
and determine
objectives

Develop resource
data




Interpret, analyze,
and evaluate data
and forecasts



Formulate and
evaluate
alternatives

Evaluate and
compare
alternatives

Developing Goals
for Nonpoint
Source Water
Quality Projects
(U.S. EPA,
1991 b)
Inventory
resources and
forecast conditions








Identify problems

Develop goals or
objectives


Formulate
alternatives

Evaluate
alternatives



Santa Clara
Valley Nonpoint
Source
Study — Volume II:
NPS Control
Program.
(SCVWD, 1990)
Initiate public
participation

Define existing
conditions

Review regulatory
problems

Define goals and
objectives
Define and
describe problems




Identify NPS
control measures

Evaluate control
measures

Develop evaluation
criteria
State of
California Storm
Water Best
Management
Practice
Handbooks
(CDM, 1993)
Define goals

Assess existing
conditions







Set priorities





Select near-term
BMPs






Urban
Stormwater
Management
and
Technology:
Update and
Users' Guide
(U.S. EPA, 1977)
Assess existing
data

Compare
conditions vs.
objectives

Determine extent
of runoff problem


Conduct
selective field
monitoring

Refine problem
estimates
Assess
alternatives






                                                             Examine and
                                                             screen measures

                                                             Select measures


Developing and
Implementing the
recommended
plan


Prepare plan
implementation
program
Implement plan


Select alternative Select best
and record decision alternative and
record decision
Reassessment of
measures
Recommend
control measures
and
implementation
program


Implement Determine
near-term program attainable
improvements
Assess program
effectiveness
                                                   18

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                  Program Activities
                                                                             Technical Activities
                     Set general
                    program goals
                    Set site-specific
                    program goals
                      Refine site-
                    specific program
                         goals
                   Monitor program
                     effectiveness
  Initiate
 program
(Chapter 3)
                                                                                Determine
                                                                             existing conditions
                                                                                (Chapter 4)
                                                                             Collect and analyze
                                                                               additional data
                                                                                (Chapter 5)
                                                                                 Assess and
                                                                               rank problems
                                                                                 (Chapter 6)
                                                                               Screen BMPs
                                                                                (Chapter?)
                                                                                   I
                                                                                Select BMPs
                                                                                (Chapter 8)
                                                                              Implement plan
                                                                                (Chapter 9)
Figure 3-1.  Urban runoff pollution prevention and control planning process.
                                                           19

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4. Collect and analyze additional data (Chapter 5)
5. Refine site-specific goals
6. Assess and rank problems (Chapter 6)
7. Screen BMPs (Chapter 7)
8. Select BMPs (Chapter 8)
9. Implement plan (Chapter 9)
While the planning process generally is intended to be
followed in  sequence,  the process  can always  be
altered  depending  on the  specific  situation.  For
example, a  municipality might already  have begun
planning to address certain sources (e.g., storm water
or CSOs). In such cases, starting  later in this planning
process or integrating other sources into the ongoing
planning might be more efficient.
Goal  setting and refinement is  more appropriately
shown as a parallel process rather than a specific step.
Only very general goals should be considered at the
outset of a program.  Existing data should be assessed
before setting any site-specific goals. As new data are
analyzed, new findings and issues are likely to emerge.
Program goals  therefore  must  be  reevaluated  as
the  planning process  progresses.  Monitoring  the
effectiveness of what has  been implemented  is very
Important.  Since  further  planning typically will  be
required, the point of reentry in the planning process
needs to be flexible.
The remainder of this chapter describes each  step of
the planning process  in greater detail. The chapter ends
with a case study showing the process of setting and
refining  program goals for Lewiston, Maine.

Initiate Program
As a first  step in the planning process,  municipal
officials  undertaking  urban runoff pollution  prevention
and control planning should develop an overall program
structure. Early  considerations include organizing  a
program team; establishing communication, coordination,
and control  procedures for members of the planning
team  and  other  participants;  identifying tasks and
estimating the number and types of personnel and other
resources for each task; and scheduling tasks (Walesh,
1989).
For local urban runoff pollution prevention and control
programs, the program team should  be made up of
municipal   personnel:   public   works    personnel;
conservation officials;  engineering  personnel;  parks
personnel;   and  planning  and  other  officials  who
regularly deal with or control issues such as utilities,
land  use  and  zoning,  development  review,  and
environmental  issues.   The   team   should    be
muttidisciplinary and  able to address the engineering,
land use, and environmental issues that will need to be
resolved. It is important to involve all entities, including
political officials and the public, who have a stake in the
program outcome. To win support for the end result, a
shared ownership of the process is necessary. Given
that municipal boundaries typically do not coincide with
watershed  boundaries,  individuals  from all affected
communities  should  be  involved  in  the  program.
Depending on the size and complexity of the program,
private consulting resources might  also be necessary.
In addition, involving officials of other agencies at the
county, state, and federal levels is prudent, especially if
one  of these  agencies is  directly responsible  for
controlling  sources  within the watershed. Also, such
agencies might have regulatory oversight and might be
able  to   contribute  funding  or  provide  technical
assistance. Based on their potential contribution to the
program, their role could consist of participation on a
technical  or  management  advisory  group. Further
discussion on program team  composition is provided in
Chapter 9.

Initiating  the  program also  includes establishing the
program  management tasks necessary for successful
program  execution. Methods of project management
and control might already be  in effect in the municipality
or may be developed  specifically for  the  program,
particularly in  the case  of  multiagency  involvement.
These tasks include estimating, forecasting, budgeting,
and controlling costs; planning, estimating, and scheduling
the program activities; developing and evaluating quality
control practices; and developing and  controlling the
program  scope. The program team also will have to
develop a funding plan, as well as a public information,
education, and outreach program.

Once the program team is assembled and the program
is structured, the remaining portions of the planning
process can be undertaken.

Goal Setting

Setting goals is a key aspect of the planning process,
and refining goals is an ongoing consideration. Projects
such  as  those  discussed in this handbook, some of
which deal with multiple point and nonpoint sources,
require  an integrated   urban  runoff  management
program,  including  flood,  drainage,  and  pollution
prevention  and control.  Successful implementation of
these programs depends on establishing clear goals
and objectives that are quantitative, measurable, and
flexible (U.S. EPA, 1991c). Setting  goals is a process
that moves from less to more specificity as additional
information on the watershed and  water resources is
obtained.  Figure 3-1 shows the  iterative  nature of
setting  program goals  as the  planning  process
proceeds. As noted earlier,  site-specific goals  should
not be set at least until existing conditions are assessed.
                                                  20

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Types of Goals

The two main types of urban runoff goals are water
resource-   and  technology-based   goals.   Water
resource-based goals  are  based on receiving-water
standards which consist of designated uses and criteria
to   protect  these   uses.  For   example,   water
resource-based goals  may relate to uses, such  as
"opening half of the currently closed shellfish beds."
They also  may  consist of  more  specific pollution
reduction goals, such  as lowering the Trophic State
Index or reducing the number of oxygen-demanding
substances in a lake. In addition, water resource-based
goals can place numerical limits on the concentrations
of  specific  pollutants.  Further, examples  of  water
resource-based  goals  include  no  degradation,  no
significant  degradation,  and  meeting water  quality
standards!  As a  defining  characteristic  of  water
resource-based goals, the success in meeting such a
goal  is determined by  the  condition of  the  water
resource. Applying water resource goals to urban runoff
problems, however, might be difficult since water quality
standards would need to be assigned to intermittent and
variable events.

In contrast, technology-based  goals  require specific
pollution prevention  or  control  measures  to address
water resource problems. They can  be very general,
such as "implement the nine minimum technologies for
CSO control," or very specific, such as "implementing
runoff detention at 50 percent of the industrial sites in a
watershed." A municipality might be able to determine
the effectiveness  of implementing these goals without
conducting  future water quality monitoring. With most
technology-based  goals,  implementing  the  control
measures is presumed to be adequate to protect water
resources.  Monitoring,  however, is still essential after
implementation to gauge the program's effectiveness
and to see if the desired environmental results are being
achieved.

The types of goals set by a municipality usually depend
on  the natural or political forces driving urban runoff
control and the public's level of knowledge about the
affected water  body. If a  community undertakes  an
urban runoff pollution prevention and  control program
because it  has lost a resource (e.g., closed shellfish
beds or loss  of  fishing or  swimming  areas),  the
community usually will set a  water quality-based goal
linked directly to   recovering  the   resource.  If  a
community  expects to  lose a resource from a known
source (e.g., a farm located directly  on a stream or
frequent oil spills from an industrial plant),  its goal can
be specific  and technology-based. On the  other hand,
communities  that are  not currently suffering  from
obvious problems with a water  resource might launch
urban runoff pollution prevention and  control programs
only to comply with regulations (see Chapter 2). These
communities might not know or be aware of existing or
potential water quality problems.  Even under these
conditions, however, setting general goals,  such as "to
meet the requirements of the regulations," is not only
possible, but important. Even this general goal directs
the program's focus, which  then can be made more
specific as more information is obtained. In these cases,
the municipality typically has to rely on state-mandated
goals for the specific water body of concern or general
state mandates for the condition of all water bodies.

Although the water resource- and technology<-based
goals  discussed  above  differ  in   specificity  and
complexity, they are all valid for an urban runoff pollution
prevention and control plan.  Goal-setting will  focus the
scope of work throughout a program.

Reassessing Goals
Far  from  static  statements,   water resource-  or
technology-based  goals  should  be  reassessed  as
appropriate in  the planning process. Once early goals
have been stated for a watershed or receiving water, all
future  actions affecting  these  resources  can  be
considered against this backdrop and the goals can be
reassessed. As more information is gathered, the goals
can be maintained, made more specific, or changed
completely. By the time the program is defined  and
ready to be implemented, however, fairly specific goals
should exist so that program evaluators can determine
whether or not goals have been met.

Determine Existing Conditions
After initiating the program, the planning  team must
develop a greater understanding of existing watershed
characteristics and water resource conditions in order
to:

• Define  existing  conditions pertinent to the urban
  runoff pollution prevention  and control program.

• Identify data gaps.
• Maximize use of existing  available information and
  data.

• Organize a diverse set of information in a useable
  way.
The required research is typically done by  gathering
existing   available  watershed   information   (e.g.,
environmental,  infrastructure, municipal,  and pollution
source  information),  as well as receiving-water data
(e.g.,  hydrologic, chemical,  and biological data,  and
water quality standards and criteria). This  information
can be obtained from various  data  bases,  mapping
resources, and federal, state, and local agencies. The
information can then be  used to develop watershed
maps;  to determine water,  sediment, and  biological
quality;  and to establish the  current status  of streams,
                                                  21

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 rivers, and other natural resources. Once these data are
 gathered,  the  program   team  can  organize  the
 information  into  a coherent  description of existing
 conditions and determine gaps in knowledge. In this
 way,  the existing conditions  of  the watershed  and
 receiving waters can  be  defined. This step in the
 planning process is discussed  in Chapter 4.

 Collect and Analyze Additional Data

 Even  under the best circumstances,  municipalities
 usually will  not have  all  the  required information to
 describe  adequately  a   program  area's  existing
 conditions. The program team, therefore, might have to
 gather additional information through field investigation
 and data collection. With this additional information and
 existing data, the program team can evaluate more fully
 the existing conditions of the watersheds  and water
 resources of concern. Given the cost and time involved
 in data gathering, the program team will have to weigh
 the benefits of additional data  collection against using
 limited funds for plan development and implementation.
 If the additional data are required, a plan to gather these
 data  must be  developed. The plan should include
 an assessment of available  staffing  and  analytical
 resources; identification  of sampling stations, frequencies,
 and parameters for sampling and analysis; development
 of a plan to manage, analyze, and interpret the collected
 data; and analysis of available  or  needed financial
 resources. This  step  in  the planning process is
 presented in Chapter 5.

 Assess and  Rank  Problems
 Once sufficient data have been collected and analyzed,
 the data can then  be  used to assess and rank the
 pollution problems. Based on data gathered in earlier
 steps, the team will need to develop a list of criteria to
 assess problems. These criteria are used in conjunction
 with water quality assessment methods  and models
 to  determine current  impacts  and future  desired
 conditions.
 Having determined the problems of concern,  the project
 team can rank these problems to set priorities for the
 selection and implementation  of  pollution  prevention
 and control  measures. The emphasis on  ranking of
 resources and  problems  is  central  to  EPA's  NPS
 strategy. This concept assumes that focusing resources
 on targeted areas or sources enhances water resource
 improvement. Further,  it assumes that demonstrating
water resource benefits increases  public support of
 urban runoff pollution prevention and control programs
as  citizens become  more  closely attuned  to overall
water quality goals (U.S. EPA,  1987). The municipality,
therefore, should investigate the  sources of pollution
affecting the high-priority water  bodies to determine the
 order in which to address these, problem sources. In
 many  cases,  an analysis at the  sub-basin level is
 needed  to  determine which  areas of a  watershed
 contribute the greatest loadings. The data gathered in
 the  previous  step  will  be particularly useful in  this
 assessment.  Also,  municipalities  should  investigate
 water resources within their region to develop priorities
 so that limited resources can be targeted to areas with
 greatest potential for improvement. Various levels of
 detail can be used in this assessment, ranging from
 simple unit load methods to complex computer models.
 This ranking procedure, one of the more subjective and
 difficult steps in the  urban runoff  planning  process,
 is  described   in  Chapter  6, along  with  problem
 assessment.

 As additional  data  are collected and  evaluated, the
 program team should refine the goals  of the program
 and make them more specific. For example, at the
 beginning of the program, the municipality might have
 been aware of excessive algal blooms in  a lake but
 might not know the cause. An initial goal of the pollution
 prevention and control program might have been simply
 to  eliminate   these   algal   blooms.  After  further
 investigation  and   water   quality   sampling,   the
 municipality  might  discover  that  continuous  high
 phosphorus loadings are  directly contributing to the
 algal  blooms. The  goal could then be  made more
 specific  by focusing  on  reducing   or   eliminating
 phosphorus sources. The initial goal, rather than being
 abandoned  in  favor of another goal,  is refined to focus
 future  actions  on  the specific causes of the water
 resource impairment.

 Screen Best Management Practices
 Once  the  water  resource   problems  have  been
 prioritized, specific water resource problems and their
 sources can be addressed. The program  team should
 compile  a  list of  various pollution prevention and
 treatment  practices  and review   them   for  their
 effectiveness  in solving the  prioritized problems. To
 assist  the  municipality in gathering  information on
 various practices, Chapter 7 includes brief descriptions
 of various nonstructural and structural  practices, and
 includes  references for additional  information.  Also
 described is the initial BMP screening  step, when
 potential practices are reviewed for their applicability to
 the watershed and water resource problems of concern.
 While the team initially faces a large number of potential
 practices,   obviously  inappropriate   practices   are
 eliminated in this step based  on criteria  such as the
 primary pollutants removed, drainage area served, soil
 conditions,  land   requirements,   and   institutional
 structure. Following this initial  screening,  the program
team  will have a  list  of  potential  practices to be
evaluated further.
                                                  22

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 Select Best Management Practices

 During this step, the program team investigates the list
 of potential pollution prevention and treatment practices
 developed from the previous step to determine which to
 include in the plan. More specific criteria should be used
 for analyzing these potential practices than during the
 initial  screening.  To make  the  final  selection, the
 program team must use the analytical tools developed
 during the ranking and assessment of problems, as well
 as  decision  factors such  as  cost, program  goals,
 environmental effects, and public acceptance. As with
 the  initial screening step, these evaluation criteria
 depend   on   established  priorities.  Generally,  the
 selection process  yields  a recommended  system of
 various  pollution  prevention and treatment practices
 which  together address  the  pollution  sources  of
 concern. Availability of required resources to implement
 the practices  is a  major  consideration. If needs and
 resources don't match, the municipality might have to
 adjust its expectations to  what  realistically can  be
 accomplished.  Both  structural  and   nonstructural
 practices might be  required. This step in the planning
 process  is discussed in Chapter 8.

 Implement Plan

 After choosing  pollution   prevention and  treatment
 practices, the  program team moves  from planning to
 implementation, which often occurs through a phased
 approach. Inexpensive and well-developed  practices
 can  be implemented early in the program as pilot or
 demonstration  studies;   and these  results  might
 influence further  implementation. Given the added
 requirements   of   implementation,   operation,  and
 maintenance, the original program team might expand
 to include members with more construction experience.
 Also, funding  sources are  needed  for initial capital
 expenses and continuing  operation and maintenance
 costs.  Nonstructural practices must  be implemented,
 and the team must arrange for the detailed design and
 construction:of structural practices.

 During this  step,  program responsibilities must be
clearly delineated. All involved entities must be familiar
with and accept their role in implementing and enforcing
the plan.  Continuing activities also should be clearly
 defined and monitoring  schedules should be  set to
 determine the  program's effectiveness in meeting its
 goals. Maintenance programs should be developed so
 that  structural  practices  continue  to  operate  as
 intended. Finally, the municipality should be aware of
 available  federal and state technical assistance that
 could help throughout implementation of the plan. This
 step in the planning process is discussed in Chapter 9.

 Summary

 This handbook is based on the process outlined in this
 chapter. The process includes setting goals, analyzing
 existing data, collecting and analyzing additional data,
 assessing and  ranking  problems,  screening BMPs,
 selecting  BMPs, and defining and implementing the
 plan. The process is founded on approaches described
 both   in   technical  literature  and  in   regulatory
 requirements. Each step should be followed to develop
 an  effective  and  realistic  urban   runoff , pollution
 prevention and control program.

 Developing and implementing an urban runoff  pollution
 prevention and control program at the municipal level is
 a multidisciplinary effort that requires a program team
 that has varied experience and is familiar with  program
 requirements. The process presented in this handbook
 is   designed  to provide  program  teams  with a
 step-by-step  approach to conducting these types of
 planning programs.

 Planning,   however,  is  only  the first phase in the
 protection  of water resources.  The program team
 should keep in mind the ultimate goals of the program.
 Since implementation and program assessment are
 important, the setting and refinement of program goals
 is key. By reaching an  early consensus on program
 goals and reassessing goals during the process, the
 program team can increase the possibility of successful
 implementation.   During   the  planning   process,
 increasing knowledge about the area's water resources
 and  characteristics  of  the watersheds  should be
 emphasized.  All these  steps are  important  to the
 program's ultimate success.

The following case  study outlines some of the initial
steps in program development and initial goal setting for
Lewiston,  Maine.
                                                  23

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                                      Case Study:
                              City of Lewiston,  Maine,
         CSO, Storm Water, and Nonpoint Source Planning Program


Background
The city of Lewiston, situated on the Androscoggin River,  is Maine's second largest city. Lewiston and
its sister city, Auburn,  serve as the industrial, commercial, and service center for Maine's southern,
central,  and western regions. With a population of about 40,000,  Lewiston has a combination of
residential,  commercial,  industrial, and parkland  use with  limited  agricultural  land. It  has seven
watersheds that will be described later.
In 1991, Lewiston launched a planning program to address issues such as CSO impacts, storm water
management, and nonpoint source control. Known as the city's Clean Water Act  master planning
program, the effort was undertaken for a number of reasons: Maine required the city to develop a facilities
plan for  CSO abatement, and there was potential for development of new storm  water and NPS
requirements at the state and federal levels. Incorporating  these considerations into an overall planning
effort_a proactive approach—would meet requirements of existing regulations and prepare the city for
future requirements. By undertaking a  program  consistent with watershed needs, Lewiston chose a
comprehensive rather than  fragmented approach based on different,  and possibly conflicting and
overlapping, regulatory requirements. The city also decided to set water resource-based goals that would
be as consistent as possible despite the changing regulatory environment.

Program Initiation
The city's public works department assumed responsibility for the program and formed a team that would
meet regularly and guide the planning process. The team  included individuals from:
•  Department of Public Works
•  Planning Department
•  Lewiston-Auburn Water Pollution Control Authority
•  Highway Department
•  General public
The public works department assigned a staff person who expended a significant amount of his time to
support the effort. The department also secured funding (100% from city funds), developed a scope of
services, and hired an engineering consultant to perform technical tasks and provide services which
were beyond Lewiston's capability or available resources.

Regulatory Setting
One of the program team's first tasks was to compile information on current federal and state regulations
that potentially pertained to the planning effort. A series of contacts were made, especially with state
regulatory personnel, to determine the status of  regulatory activities.  Information on current regulatory
setting was reviewed (as summarized in Table 3-3) and  appropriate state regulatory personnel were
identified. Changes were occurring in several areas, especially CSO and storm  water, that needed to
be monitored and incorporated into the program.

Set Initial Program Goals
Using available data, initial goals were developed along with assessment of existing conditions. This
assessment is described in a companion case study at the end of Chapter 4. A basic  goal was that the
program should result in an understanding of and compliance with current and  upcoming regulations
related  to CSO, storm water, and NPS  control. Initial goals  were  also established for each major
watershed. The watersheds are shown in Figure 3-2, and their characteristics are listed in Table 3-4.
                                            24

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 Table 3-3.  Federal and State Regulation of Urban Runoff
 Regulation                        Federal
                                                                           State
 Combined Sewer Overflows
 Storm Water NPDES Permits
 Pollution Prevention Act
 Safe Drinking Water Act

 Nonpoint Source Pollution
 Regulations
 Coastal Zone Nonpoint Source
 Pollution Control
 Clean Lakes Program
 National Estuary Program
 Agricultural Nonpoint Source
 Programs
 Comprehensive Planning/Growth
 Management
 Shoreland Zoning
National policy (currently under review)
CWA, Section 402 NPDES regulations
National Pollution Prevention Strategy
Surface Water Treatment Rule

CWA, Section 319

Coastal Zone Management Act, Section
6217(g)
CWA, Section 314
CWA, Section 320
Funding and guidance provided at the
state level through SCS
Not applicable
Not applicable
 State CSO policy (approved by EPA)
 General permit (does not currently affect
 Lewiston)
 Future impacts
 Municipal permits
 Municipally owned industrial facilities
 Not applicable
 State allows variance; however, not
 applicable to Lewiston
 General guidance from state NPS office

 Probably not applicable (coastal
 boundaries not yet determined)
 Limited funding for state program
 Lewiston and Auburn in upper reaches of
 Casco Bay watershed; CCMP  being
 developed
 SCS assistance to farms; no significant
farms in city
Growth management plans required;
 Lewiston obtained approval
 Requires special  zoning practices within
75 ft of streams and 250 ft of other water
bodies; Lewiston obtained approval
                                                                       	Watershed boundaries
                                                                       	  Streams
Figure 3-2.  Watersheds in Lewiston, Maine.
                                                       25

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Table 3-4.   Land Use Near Major Watersheds in Lewiston, Maine
Watershed Name                   Size, ac        Land Use Description
No-Name Pond
No-Name Brook
Stetson Brook
Hart/Goff Brooks
Salmon/Moody Brooks
Japson Brook
Androsooggin River
  750        Rural/residential, shore line cottages
10,000        Mainly undeveloped, some residential
 3,000        Rural, residential, and commercial/industrial
 1,600        Residential, commercial, and industrial
 1,900        Primarily undeveloped, minor agriculture
 1,500        Residential and institutional
 2,300        Urban in central core, undeveloped or industrial In outlying area
The program team held a workshop to facilitate discussion and obtain input on the city's water resources
and appropriate initial program goals. A form similar to that shown in Table 3-5 was used to compile the
information. Each watershed was discussed, including  its water quality classifications, current uses,
known problems, desired  uses, and  goals. A qualitative  assessment or ranking  of the individual
watersheds was  included to indicate the relative importance of the water resources to the city. This
procedure was done to assist later decision-making which could involve setting priorities for funding or
phasing of activities.
Table 3-5. City of Lewiston Initial Water Resources Goals

Watershed Water Quality
Name Classification
No-Name A
Pond
No-Name C
Brook
Stetson Brook B
Hart and B
Goff Brooks



Salmon/Moody B
Brook

Jepson Brook B

Androsooggin C
River

Ground water GWA*

Current Uses
Aesthetics
Recreation-fishing,
boating
Aesthetics
Aesthetics
Aesthetics



Aesthetics

Drainage

Aesthetics
Recreation-fishing,
boating

Drinking water
supply (for town of
Lisbon)

Known
Problems
Algal blooms
Septic tank
discharges
Erosion (use
of ATVs)
Debris
Erosion
CSOs (one)
Erosion
Industrial
areas
Interceptor
sewer
surcharging
Agriculture

CSOs (no
visual/odor)
Debris
Point
sources
(paper mills)
Erosion
(gravel pits)
CSOs
None known
Qualitative
Assessment
of Importance
Most important
town water
resource
Second most
important town
water resource
Third most
important town
water resource
Fourth most
important town
water resource



Small
watercourses of
minor
importance
Channelized
drainage ditch

Large regional
water resource

Currently of
limited
importance to
town

Desired
Uses
Same
Same
Same, plus
fishing
Same



Same

Same

Same

Same

Goals
Maintain and protect
existing uses
Maintain and protect
existing uses
Upgrade to Class B
Meet Class B
standards
Meet Class B
standards



Meet Class B
standards

Maintain current use

Meet Class C
standards

Maintain and protect
existing uses
* Ground-water classification A.
                                                   26

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 While the initial goals were recognized as expensive and potentially not attainable in the near future,
 the interactive process was desirable when feasible in terms of cost and effort. Moreover, the goals could
 be revised if unrealistic. Consideration was given to the existing regulatory requirements in the water
 quality standards (see Table 3-6). The main differences in water quality criteria for each classification
 are for dissolved oxygen and E. coll bacteria.
 Table 3-6.  Comparison of Maine Water Quality Standards
                                                         Minimum Dissolved
                                                              Oxygen
E. coli Bacteria


Classification
AA

A



r


Designated Uses
Drinking water (with disinfection); fishing; primary
and secondary contact recreation; free-flowing
and natural habitat for fish and other aquatic life'
Drinking water (with disinfection); fishing; primary
and secondary contact recreation; industrial
process and cooling water; hydroelectric power
generation; navigation; natural habitat for fish
and other aquatic life


mg/L
As
naturally
occurs
7.0





%
Saturation
As
naturally
occurs
75




Geometric
Mean
NoJIOO mL
As
naturally
occurs
As
naturally
occurs


Single
Sample
NoJIOOmL
As
naturally
occurs
As
naturally
occurs


      B        Drinking water (with treatment); fishing; primary     7.0*      75a         84b         427b
               and secondary contact recreation; industrial
               process and cooling water; hydroelectric power
               generation; navigation; unimpaired habitat for fish
               and other aquatic life
      C        Drinking water (with treatment); fishing; primary     5.0       60          142b        94913
               and secondary contact recreation; industrial
               process and cooling water; hydroelectric power •
               generation; navigation; habitat for fish and other
               aquatic life
* From October 1 to May 14, the 7-day mean dissolved oxygen is not less than 9.5 mg/L, the 1-day minimum is 8 0 mq/L
  May 15 to September 30.

In some cases, where desired uses of the water  resource were being met, maintaining and protecting
these uses was set as an initial goal.  For some  brooks,  aesthetics was the only use of concern; the
initial goal of meeting Class B standards was set  even though the Class B standard also allows fishing
and swimming. For Jepson Brook, which is a channelized drainage ditch, meeting Class B standards
was not a priority. For No-Name Brook, there was a desire to upgrade the standard to Class B from
Class C. Thus, the variety of watersheds and water resources was reflected in the range of initial goals.

Assessment of Existing Data

An extensive effort was made to assess existing information and data, as described in a separate case
study at the end of Chapter 4. The following conclusions pertaining to the program's initial goals were
based on already available data:

• The city has an aggressive and extensive regulatory control system which addresses many NFS and
  storm water control issues; with minor improvements, this system  could fulfill the goals of maintaining
  and protecting existing  uses.

• Virtually no water quality data or information on any of the brooks in the city are available; more
  information is needed to assess the existing conditions and establish goals for these systems.
• Extensive data exist on the Androscoggin River, which does not meet Class C standards;  much of
  the pollution appears to stem from upstream sources, but the contribution of CSOs  needs to be
  defined better.
                                               27

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     Future Activities
     Several activities are planned for implementation. The data collection program (described in the separate
     case study at the end of Chapter 4) will be CSO-related  and implemented in 1993. Additional data
     collection is being considered beyond that effort. After the  initial planned data collection activities, the
     initial program goals are to be reviewed and refined as needed. The city is also considering changes in
     their current regulations to control urban runoff pollution better. Lewiston also plans to implement a
     cross-connection  removal program. In the long term, Lewiston's Clean Water Act master planning effort
     plans to follow the overall planning approach outlined in this document, including data collection,
     refinement of program goals, data assessment and modeling, ranking of problems, and BMP screening
     and selection.
References
When an  NT1S number is cited in a reference, that
document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650
COM.  1993.  Camp  Dresser & McKee.  State  of
  California storm  water best management practice
  handbooks.  California State Water Quality Control
  Board.
SCVWD. 1990. Santa Clara Valley Water District. Santa
  Clara Valley nonpoint source study—volume II: NPS
  control program. San Jose, CA.
U.S. EPA. 1977. U.S. Environmental Protection Agency.
  Urban   stormwater  management  and  technology:
  update  and  users' guide.  EPA/600/8-77/014 (NTIS
  PB-275654).
U.S. EPA. 1987. U.S. Environmental Protection Agency.
  Setting  priorities: the key to nonpoint source control.
  U.S. EPA Office of Water Regulations and Standards.
  Washington, DC.
U.S.  EPA.  1991 a. U.S.  Environmental  Protection
  Agency. Developing  the watershed plan. Published
  in Seminar Publication: Nonpoint Source Watershed
  Workshop. EPA/625/4-91/027 (NTIS PB92-137504).
  Cincinnati, OH.
U.S.  EPA.  1991 b. U.S.  Environmental  Protection
  Agency. Developing goals for nonpoint source water
  quality projects.  Published in Seminar Publication:
  Nonpoint Source Watershed  Workshop.  EPA/625/
  4-91/027 (NTIS PB92-137504). Cincinnati, OH.

U.S.  EPA.  1991c. U.S.  Environmental  Protection
  Agency. Goals and  objectives for nonpoint  source
  control projects in an urban watershed. Published in
  Seminar Publication: Nonpoint Source Watershed
  Workshop. EPA/625/4-91/027  (NTIS PB92-137504).
  Cincinnati, OH.
Walesh,   Stuart  G.  1989.   Urban  surface  water
  management. New York: John Wiley & Sons, Inc.
                                                  28

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                                              Chapter4
                                 Determine Existing Conditions
 Existing conditions must be investigated and described
 prior to data collection, problem assessment, and BMP
 evaluation. An investigation includes gathering, reviewing,
 analyzing, and  summarizing  mapping   resources,
 hydrology, water quality and other environmental data,
 as well as municipal planning information for the subject
 region, county, municipality, or watershed. A description
 of existing conditions has two major components:

 •  Watershed  description,  which characterizes  the
   sources of  runoff and the "causes" of water resource
   problems.

 •  Receiving-water description, which characterizes the
   receptors of the watershed sources and their effects.
 The watershed  description defines the watershed area
 and its subwatersheds and further identifies pertinent
 geographic and environmental  features (e.g., land use,
 geology,  topography,  and  wetlands),  infrastructure
 features  (e;g.,   sewerage and  drainage  systems),
 municipal data  (e.g.,  population, zoning, regulations,
 and ordinances), and  potential pollution  source data
 (e.g., in-stream sediments, landfills, underground tanks,
 and point source  discharges). The  receiving-water
 description provides water  resource  information for
 water  bodies affected  by the watershed, which can
 include any  type  of  receiving  water (e.g.,  rivers,
 streams, lakes, and estuaries) and its sediment and
 biota as well as ground water.

 This chapter  describes an approach and  rationale for
 defining  and  assessing   existing  conditions.  The
 objectives are to develop a convenient way to organize
 information, to develop a definition of existing conditions
 pertinent  to  urban runoff pollution  prevention arid
 control, to identify data gaps to be addressed under a
 field sampling program, and to maximize use of existing
 available information. Extensive applicable information
 usually is  available  from   municipal  government
 departments,  state and federal agencies, and private
vendors, as well as  from files and data bases of maps
and  environmental  data.  The more  persistent and
thorough  the investigator,  the  more  information  is
obtained. These early efforts support future  phases of
planning by:
 •  Providing a basis for establishing and reassessing
   water   resource   protection   and  improvement
   objectives.
 •  Identifying pollutants of concern and related effects
   on water resources.

 •  Providing a base map for locating pollution sources
   and controls.
 •  Defining areas of concern where pollutant loadings
   pose a high environmental or public health risk and
   where source control efforts  should be focused.
 •  Providing  information  for  development  of  water
   quality models, if needed.
 •  Planning, designing, and implementing BMPs.
 •  Evaluating post-implementation  improvements  and
   beneficial use attainment.
 •  Identifying areas of good water quality and high value
   to focus protection efforts.
 This chapter first discusses how to prepare a watershed
 description,  including the types of information needed,
 sources of watershed mapping and data, and methods
 for organizing and presenting the information. For areas
 where watershed mapping  does not exist or needs to
 be verified,  techniques  to   develop mapping  are
 discussed. Next/the  chapter  describes developing  a
 receiving-water description including the types of water
 resource data useful in investigating pollution sources
 and  assessing  receiving  water conditions, sources of
 data, and methods for organizing and evaluating the
 information.

 Preparing a Watershed Description
The watershed is the entire surface area that drains into
 a particular water body. Runoff  from precipitation falling
on the watershed  flows through  systems  of storm
sewers, channels,  gullies, and streams to the lowest
elevation, usually to a river, lake, or estuary. Multiple
watersheds often exist in a study area because  many
urban runoff pollution prevention and control programs
are based upon political boundary areas, such as the
limits of a municipality.
                                                  29

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The first step in describing  each  watershed  is  to
delineate the  watershed  and  smaller watersheds  or
subwatersheds within it,  some  of  which  might  be
identified later in the planning process as  significant
contributors to water resource impacts. Once the areas
are delineated, the municipalities and other entities with
jurisdiction for actions within them should be identified.

In  many states, watershed  delineation  mapping  is
available either on large base maps or through a digital
mapping resource. If mapping is not readily available,
however, watershed  delineation  can be done  using
topographical  maps; watersheds can be delineated  by
connecting  the  points  of highest elevation  on land
surrounding the  subject water body. Watershed  maps
can be  prepared using town or  county topographic
maps, which are typically available at scales suitable for
use as a base map. These scales range from 1 in=200
ft for small watersheds,  to 1  in=2,000 ft or higher for
large watersheds. The watershed map will serve as the
base map for additional data.

Types of Watershed Data
Table 4-1 outlines the types of mapping  available for
preparing a watershed description and  the pertinent
information  in these sources.  Land use data are
especially important  to  obtain given the relationship
between land use  and  urban  runoff  pollution (see
Chapter 1). Land use information can be separated into
either a few general  categories  or many   specific
categories; an appropriate level of detail  should  be
selected before undertaking a mapping effort. Table 4-2
presents two options: 9 general categories of  land use
and 37 specific categories. In addition to these options,
combinations  of the two  may also  be considered.
Classifications should  be  selected  based   on the
diversity of land use types in the watershed and the
level of detail  of existing information. They can also  be
selected so that they are consistent with  local zoning.
At  a minimum,  however, classification should include
major categories of land use, such as residential areas,
commercial and industrial developments, agricultural
operations, forested areas, open space and park land,
and other significant land uses that could affect water
resources.

Once the watersheds are delineated on a base map and
land use categories have been  selected, additional
features and  data  for each watershed are compiled.
Pertinent information includes:

• Environment
  - topography,
  — land use,
  — recreational areas (e.g., beaches, boating areas),
  — soil and surface/bedrock geology,
Table 4-1.  Use of Mapping Resources for Urban Runoff
          Planning
Types of
Mapping
Use in Urban Runoff Planning
Drainage
basins

Topographical
Land use
Soil/geology
Vegetation
Zoning
Infrastructure
Assessor
maps

Aerial
photographs


Water bodies
Identify and delineate subwatersheds
Identify and delineate pollution sources

Delineate drainage areas, slopes, and
patterns
Calculate hydrologic model variables
Identify areas prone  to erosion

Qualitatively analyze runoff quantity and
quality
Identify land use trends
Assess effects of land use on water quality
Locate potential sites for installation of control
structures

Evaluate erosion potential
Determine infiltration capacity for BMP design
Determine depth to bedrock
Identify depth to water table
Determine treatability of soil column

Identify areas protected by wetland regulations
Identify vegetative buffers
Identify undeveloped areas (e.g., forested
areas)

Identify priority areas based on type of
development
Identify potential areas of future development
Evaluate zoning changes and other
regulatory controls

Locate drainage system discharges
Design drainage system modifications
Identify opportunities for retrofit
Design storm water sampling program
Locate existing control practices
Locate utilities for placement of controls

Determine land ownership
Determine land use
Identify resource areas
Identify areas of erosion

Delineate potential problem areas
Identify pollutant transport considerations
   — vegetation,
   - natural resources (i.e., wetlands, wildlife resources,
     and shellfish beds),
   - temperature,
   - precipitation, and
   - hydrology.

   Infrastructure
   - roads and highways,
   - storm drainage systems,
   - sanitary sewer systems,
   - treatment facilities, and
   - other utilities (i.e., water, electric, gas).
                                                       30

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 Table 4-2.  Land Use and Land Cover Classification System
          (Anderson, 1976)
 Level I
Level II
 1. Urban or      11. Residential
   developed land 12. Commercial and services
               13. Industrial
               14. Transportation, communications, and utilities
               15. Industrial and commercial complexes
               16. Mixed urban or developed land
               17. Other urban or developed land

 2. Agricultural    21. Cropland and pasture
   land         22. Orchards, groves, vineyards, nurseries, etc.
               23. Confined feeding operations
               24. Other agricultural land

 3. Rangeland    31. Herbaceous rangeland
               32. Shrub and brush rangeland
               33. Mixed rangeland
 4. Forest land    41. Deciduous forest land
               42. Evergreen forest land
               43. Mixed forest land

 5. Water        51. Streams and canals
               52. Lakes
               53. Reservoirs
               54. Bays and estuaries

 6. Wetland       61. Forested wetlands
               62. Nonforested wetlands
 7. Barren land    71. Dry salt flats
               72. Beaches
               73. Sandy areas other than beaches
               74. Bare exposed rock
               75. Strip mines, quarries, and gravel pits
               76. Transitional areas .
               77. Mixed barren land

 8. Tundra        81. Shrub and brush tundra
               82. Herbaceous tundra
               83. Bare-ground tundra
               84. Wet tundra
               85. Mixed tundra
9. Perennial      91. Perennial snowfields
  snow or ice    92. Glaciers
 • Municipality
  — population,
  - zoning,;
  — land ownership,
  — regulations,
  - ordinances, and
  - municipal  source  control  BMPs  (e.g.,   street
    sweeping and catch basin cleaning).

  Potential pollution sources/existing structural BMPs
  - landfills,
  - waste handling areas,
  - salt storage facilities,
  - vehicle maintenance areas,
  - underground tanks,
  - NPDES discharges,
  — pollution control facilities,
   -  retention/detention ponds, and
   —  flood control structures.

 Once these data are collected, some can be plotted on
 the watershed base map if useful.

 Sources of Watershed Mapping and Data

 Watershed data are site specific and can be obtained
 from  municipal  government  departments,  state and
 federal agencies, and private vendors, and by searching
 files  and data bases of maps and environmental data.
 Much of this information  is contained in reports and
 maps dealing with  the watershed. At the federal and
 state levels, mapping is increasingly available in digital
 form  that   can  be  downloaded to  a geographic
 information  system (GIS)—a flexible  and  powerful
 computer-based  tool  that  can   store,  display,  and
 analyze geographical information. Digital data for use
 with a GIS are available from data bases maintained by
 many state and federal agencies, and the private sector.
 Two  major sources  of  watershed  data  are  U.S.
 Geological   Survey   (USGS)   maps  and  aerial
 photographs. USGS maps  depict many of the  land
 attributes  shown   in  Table  4-2,  including   urban,
 residential, forested, and wetland areas, as  well  as
 roads, buildings, and water bodies. Aerial photographs
 can provide a high level of detail  on land use and also
 can be  used later in the  assessment  and ranking of
 pollution sources. Aerial photographs are generally sold
 as 9 in by 9 in prints that cover about half a square mile;
 thus  it  may be necessary to overlap a number  of
 photographs to  map an  entire  study  area. Satellite
 imagery is also available from several sources, but this
 tool is more useful for a regionwide analysis and might
 not  provide the  resolution   required for  analysis  of
 smaller   watersheds.   The   following   paragraphs
 summarize sources of available watershed mapping
 and GIS data.

 Local

 Existing watershed  mapping is most  readily available
 from  local municipal government departments that use
 mapping to track property ownership,  plan  for future
 development,  maintain public utilities, and enforce
 environmental  regulations.  Potential  local sources  of
 mapping include the following municipal offices:

 • Assessor: Maps of individual parcels,  data  on parcel
  size and property ownership.

 • Planner: Land  use maps, aerial photographs, zoning
  maps.

 • Engineer:  Storm sewer  and other  utility plans and
  structural information.

• Public Works: Utilities and maintenance activities.
                                                    31

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• Conservation: Mapping of wetlands, soils, and other
  vegetation and natural resources.

• Water Supply and distribution system utilities  and
  ownership of protected areas.

• Health: Septic system  locations and maintenance
  records, status of water resources with respect to
  public use and consumption.
• Other: Watersheds and  other information also might
  be delineated on maps prepared for special drinking
  water districts and flood control districts.

State
Watershed mapping might also be available from state
agencies responsible for  conservation, water quality,
and oversight of state programs implemented at the
local level, such as wetland  protection and health
codes.  These  maps, however, might not be as  site
specific or  as current as those  available from  local
sources and might be less accessible because of the
location or the structure of state government. One
method of locating mapping at the state level is to obtain
a  directory of state  departments  and  services  and
contact those departments that would  likely  maintain
mapping. Generally the following types of information
are available:
• State environmental  agency:  Water quality data,
  previous studies,  existing controls,  NPDES permits,
  and compliance data.
• Conservation   districts:   Farm   locations   and
  inventories, locations  of existing  agricultural BMPs,
  soil descriptions.
•  Water resources: Watershed delineations,  locations
  of potential  pollution  sources,  status   of  water
  courses, locations of public drinking water supplies.
•  Wetlands and   wildlife:  Locations   of   protected
  wetlands and other habitat areas.
• State colleges and universities: Mapping as part of
  research,   government   contracts,   or    graduate
  program  studies  at institutions  with programs  in
  environmental  engineering  or  science,  civil  or
  agricultural engineering, or biology.

In addition, some states offer an  extensive list of GIS
data. Data typically available from state GIS agencies
include:   topography,   state   plane   coordinates,
community boundaries, hydrography, major roads,  land
use, major drainage basins and  sub-basins,  aquifers,
public  water supplies,  EPA-designated  sole source
aquifers,  surficial geology, census data, hypsography,
and protected open space. Each  data type exists  as a
separate "layer" of digital  information. Many  states
publish descriptions of available data layers and  user
services.
Federal

The  federal  government  collects  and  maintains
environmental mapping and data through a number of
programs and agencies.  Readily  available sources
include USGS Earth Science Information Centers! EPA
regions, and other agencies. Several federal sources of
mapping are  listed in  Table 4-3;  some are national
offices of federal agencies that may direct inquiries to
satellite  offices  with data  for  specific regions. The
federal government also has an extensive amount of
GIS data available for use. Some of the more important
sources of these data are shown in Table 4-4. Additional
sources are available from EPA.

Table 4-3.  Federal Sources of Watershed-Related Data
Source                   Type of Information
U.S. Geological Survey
National Cartographic
Information Center
507 National Center
Reston, VA 22092

U.S. Geological Survey
EROS Data Center
507 National Center
Reston, VA 22092

U.S. Department of
Agriculture
Soil Conservation Service
(Contact the office of SCS
State Conservationist or the
State Agricultural Experiment
Station)

Hazardous Substance Sites
National Technical
Information Service
Computer Product Support
Group
5285 Port Royal Road
Springfield, VA 22161

U.S. Fish and Wildlife Service
(Contact:
National Cartographic
Information' Center
P.O. Box 6567
Fort Worth, TX 76115)
Mapping of topographic features,
land use, land cover, and slopes;
aerial photographs; and satellite
imagery


High altitude aerial photography
Soil survey reports that include
soil maps, soil descriptions, aerial
photographs, and soil
management information
including erosion potential,
suitability for septic tank
adsorption fields, and flooding
frequency

Topography, soil types, soil
conditions, and substance
storage data for specific studied ,
sites
Wetland mapping on USGS
topographical quadrangles
 Private
 Numerous private firms produce mapping, GIS  data,
 aerial photographs, and land surveys, frequently for
 municipal clients. Local firms involved in mapping and
 GIS data are listed in the yellow pages or local business
 directory. An extensive list of private GIS data sources
 and services can be obtained from private sources,
 such as trade journals. In addition, private colleges and
 universities with programs  in geology, engineering,  or
 environmental protection can be valuable sources.
                                                     32

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 Table 4-4. Federal Sources of Geographic Information
          System Mapping Data
 Source
                          Type of Information
 U.S. Geological Survey
 Room 1C402
 507 National Center
 Reston, VA 22092
 U.S. Bureau of Census
 Data User Services Division
 Room 407
 Washington Plaza
 Washington, DC 20233

 U.S. Fish & Wildlife Service
• National Wetlands Inventory
 9720 Executive Center Drive
 St. Petersburg, FL 33702

 U.S. Soil Conservation Service
 National Cartographic Center
 P.O. Box 6567
 Fort Worth, TX 76115
 Digital elevation models
 (OEMs)—digital terrain elevations
 at regularly spaced horizontal
 intervals

 Geographic names information
 system (GNIS)—proper names of
 places, features, and areas

 Planimetric data in digital line
 graph (DLG) form including
 boundaries of states, counties,
 and cities; transportation facilities
 including roads, trails; pipelines
 and transmission lines;
 hydrography including streams
 and water bodies; and
 topographical contours

 Land use and land cover (LULC)
 data on urban or developed land,
 agricultural land, rangeland,
 forested land, water, wetlands,
 barren land, tundra, and
 perennial snow and ice

 Digital political and census data
 such as roads, rivers,  political
 boundaries, address ranges, and
 zip codes
Vegetated wetland and
deep-water habitat mapping
Soils information (address shown
is for the federal SCS office; soils
information can also be obtained
from individual state offices)     :
Analysis of Watershed Data

This section discusses several methods of analyzing
watershed data  to  define existing conditions. These
methods  include development and use of watershed
maps and analysis of existing regulatory and municipal
practices and other existing BMPs.

Development of Watershed Maps

Maps are created to show watershed-related data, such
as topography, land use, watersheds and subdrainage
areas,   soils,   infrastructure,   natural   resources,
recreational  areas,  special fish  and  wildlife  habitat
areas, and existing pollution control structures. All this
information   is  important in  urban  runoff  pollution
prevention and control planning. If maps are generated
from  information that  is several  years  old,  field
investigations might need to be conducted to verify and
update the information. The most efficient way to verify
this information is through a "windshield survey." In
urban and suburban areas, most watershed areas are
accessible by car. Field observations are compared with
 existing maps, and changes or additions are traced onto
 the base map.

 When  required information is not available from  the
 sources  discussed in the previous  section, a  more
 complete survey of the watershed will  be required. In
 small watersheds  of  a few acres, these surveys  are
 typically  conducted by car and on foot. To conduct a
 survey   of  a   large  watershed,   however,  aerial
 photographs can supplement the site investigations and
 provide a more complete picture.
 Another  method of generating watershed maps  is by
 computer. The data in a GIS are organized into thematic
 layers  (such as land use, water bodies, watersheds,
 topography,  or  transportation)  which  can be overlaid
 and  plotted  in  any  combination. In  addition,  GIS
 systems are equipped with a data management system
 that  can organize  and  store  text  and numerical
 descriptive  information. This information  can be very
 basic, such as whether a  land  use in  a particular area
 is  residential  or  industrial,   or  it   can  be  very
 sophisticated,  consisting  of  multiple tables of  data,
 including  land  ownership   information,  discharge
 monitoring report information, soils information, or water
 quality  information.   Given the  technical  expertise
 required  and the  capital  expenditures for computer
 hardware and software, the use of a GIS might not be
 feasible for some urban runoff pollution prevention and
 control program teams. A  GIS requires  an appropriate
 personal  or mainframe computer and a graphics plotter.
 Developing new mapping  for  an area,  whether using
 GIS, aerial survey, or other means, can be expensive
 and time consuming.  The urban runoff  planning effort
 should not turn into a mapping and GIS effort. Since
 base mapping  and GIS  tools  have  numerous  uses
 within a  community, development  of such a system
 should be considered  as a separate program.

 Use of Watershed Maps

 Once watershed maps have been developed, additional
 data  can be obtained by  measuring  the area of the
 watershed and  its  subwatersheds—useful information
 for calculating runoff flows  and pollutant  loads from the
 watershed. Available methods for measuring area range
from manually measuring to using an electronic digitizer
to using GIS software. In one method,  a grid overlay is
created  on  the  watershed  base  map  of  known
dimensions and the area is approximated by counting
the grid  squares in  the  watershed.  Another  similar
method is to use a planimeter,  a device designed to
trace the watershed boundary. To use a digitizer, which
functions  as a computerized planimeter, the map is
placed on a surface  underlaid  by  an electronic grid
system. The boundary of the watershed is traced with
an  electronic  pointer  which  digitally  records   the
coordinates,  and the area  is then  calculated  by
                                                    33

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computer. In addition, GIS software has algorithms that
can be used to measure area.
Once  the  watersheds  and  subwatersheds  are
delineated and the existing conditions are indicated, the
total area of each  land  use  category for the entire
watershed and each subwatershed can be calculated.
This calculation is important because each type of land
use tends to have its own pollutant loads and urban
runoff pollution prevention and control issues. After the
runoff from each type of land use is characterized,
future changes  in pollutant  loading due to  planned
changes in land use can be estimated  and used to
assess potential future impacts and control scenarios.
These data will be important to the problem assessment
and ranking process  described in Chapter 6.
Other land use analyses can be conducted by mapping
and  reviewing  different  watershed attributes.  These
analyses  can  be  facilitated  by creating overlays
depicting  individual  watershed  attributes   or  by
displaying selected  thematic layers on a  GIS. For
example, historical land use changes can be assessed
by   comparing   historical   mapping   from   USGS
topographical  maps,  which  are  based  on  aerial
photography and periodically updated, thus documenting
land use changes over time. In many urban areas, the
USGS maps exist from as early as the 1880s. Recent
changes in land use can be used to focus source control
efforts, to locate new sampling stations, or to  modify
land use regulations.

Analysis of Regulatory and Municipal Practices
Analyses  of other types of watershed data generally
consist of creating tabular summaries, plots and figures,
or maps designed to describe the major characteristics
of  each  data  type  and  subtype.   Public   works,
engineering,   planning,   and   health   department
personnel can assist in developing a profile of existing
regulations and practices. Table 4-5 is a simple format
for  presenting   existing  municipal   practices;  the
information in this table is very general, indicating only
whether or  not certain practices  are  used. The
comparison  also can be more detailed  as shown  in
Table 4-6, which describes the actual characteristics of
each practice,  such as the  equipment used  and
frequency of actions.
In addition to  these municipal practices, regulatory
control practices affecting urban runoff pollution should
be investigated and summarized. Table 4-7 outlines an
example review of local subdivision  regulations that
could be used  to prevent  and reduce urban runoff
pollution in four communities. The table analyzes the
regulations' ability to provide runoff quantity  control,
solids control, and other pollution control. Such a review
can  be developed for all regulations (e.g.,  zoning,
wetlands, earth removal, and special protection districts)
Table 4-5.  Use of Nonstructural Practices in Study Area
         Watersheds (Adapted from Woodward-Clyde
         Consultants, 1989)
Control Watershed
Practices 1
Street sweeping
Litter control
Public education
Pet waste
removal
Local ordinances
Fertilizer control
Reduced
sanding and
salting
Catch basin
cleaning
Hazardous
waste collection
days
Yes
Yes
Yes
No
Yes
No
Yes
Yes ,
Yes
Watershed
2
Yes
Yes
No
No
No
Yes
Yes
No
Yes
Watershed
3
No
Yes
No
Yes
Yes
Yes
No
Yes
No
Watershed
4
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
No
Yes = Control measure exists
No = Control measure does not exist
that could affect urban runoff pollution. Generally, the
municipality should investigate all aspects of current
practices that could affect storm water runoff quality,
including the practices and regulations shown in Tables
4-5,  4-6,  and 4-7,  as  well  as  others:  special
requirements for stream corridor preservation, buffer
zones,  and open  space  preservation; septic system
planning and testing  requirements;  and regulations
pertaining  to nontidal  wetlands.  These issues are
discussed further in the regulatory control section of
Chapter 7. An example analysis of both regulatory and
municipal urban runoff practices is provided in two case
studies at the end of this chapter.

Contents of a Watershed Description

Once the information on existing conditions has been
gathered  and  the watershed  maps  have  been
developed,  the watershed can  be  described.  The
watershed  description  is organized by data type (i.e.,
environmental,  infrastructure, municipal,  and  potential
sources/existing BMPs). Each  data type has its own
section with a narrative  description of each data subtype
supported  by appropriate tables  and/or maps.  The
maps and data developed in the previous steps provide
the primary information in the description. While not all
this information will be of immediate use to the program
team at this stage, it could be important as planning
continues.

Information gaps should be outlined and presented  in
the watershed description as a first step  in developing
a plan to gather additional information  (see Chapter 5).
A summary listing of information recommended for the
                                                   34

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 Table 4-6. Frequency and Types of Nonstructural Practices Used in Study Area Watersheds (U.S.

 	Community 1           Community 2          Community 3
                                                         EPA, 1992)

                                                                 Community 4
 Street Sweeping
 Frequency
 Equipment (number)


 Catch Basin Cleaning

 Frequency
 Equipment (number)


 Solid Waste Management
Every other day on 30
major streets and once
a week on others

Mechanical (3)
Once a year
Mechanical (1): Clamp
Once a week downtown
and once a year in
other areas

Mechanical (1)
Vacuum (3)
Once a year
Mechanical (1):
Orange Peel
                                                                    Twice a year
Mechanical (1)
Twice a year
Mechanical (1)
 Roadway Sanding and Salting

 Sand:salt ratio             4:3

 Salt used (tons/road mile)     11

 Special reduced-use zones    None

 Other Nonstructural Practices

 Fertilizer and pesticide usage  None used
Animal waste removal

Illicit connection
identification and removal
No program

No program
                      1:1

                      12

                      None
Fertilizer used on town
ball fields

No program

No program
4:1

3.5

None



None used


No program

No program
Once a year, except
Lake Cochichewick
(three times a year) and
downtown (twice a year)
Mechanical (2)
Once a year
Mechanical (1): Orange
Peel
ntjsiuenuai
Commercial
Recycling program

Once a week
Twice a week
Paper
Fall leaves
Once a week
Private collection
Paper

Once a week
Twice a week
None

Once a week
Once a week
Paper
Leaves/grass
                                           7:1

                                           6

                                           None
Granular fertilizer used
for sodding

No program

No program
watershed description is provided later in this chapter,
and two examples are given in the case studies at the
end of the chapter.

Preparing a Receiving-Water Description

In addition to a watershed description, a receiving-water
description should be  prepared,  which includes  the
types of water resource data that should be sought,
sources of data,  and  methods  to  summarize  and
analyze existing  receiving-water  conditions.  Many
program areas have multiple receiving  waters, such as
tributaries, larger rivers or estuaries,  or lakes; in many
cases, adding ground water to this list could be useful.
Effective  identification   and  use of  existing  water
resources data could reduce the program schedule and
cost, most significantly by reducing additional sampling
and analysis. In  addition,  review of  historical  water
quality data provides a basis for:
• Establishing and reassessing goals.

• Documenting   the  type   and   extent
  runoff-related water resource impacts.
                 of   urban
          • Identifying data gaps that should be addressed with
            a sampling program.

          • Identifying priority areas and major nonpoint pollution
            sources.

          • Quantifying pollutant loads.

          • Documenting  impairment or loss of beneficial uses
            and water quality standard violations.

          • Documenting areas with good water quality that could
            be threatened or that should be protected.

          Types of Receiving-Water Data

          The types of water resources data that should be sought
          include:

          • Source input data (flow and quality)
            - CSO data,
            - storm water data, and
            - other NFS data.

          • Physical/hydrologic
            - physiographic and bathymetric data,
                                                     35

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Table 4-7.  Existing Regulatory Control Summary—Subdivision Control (U.S. EPA, 1992)

Subdivision Control       Community 1            Community 2            Community 3
                                                                     Community 4
Scops of regulations
Runoff Quantity Control
Opon space
Postdavelopment
flow control
Runoff recharge




Additional Controls

Solids control



Other pollution control
AH lots being
subdivided come under
Subdivision
Regulations; lots on an
accepted public way
and with sufficient
frontage are classified
as "Approval Not
Required"
Requires due regard for
maintaining natural
features and open space

None specified
None specified
None specified
None specified
All lots being
subdivided come under
Subdivision
Regulations; lots on an
accepted public way
and with sufficient
frontage are classified
as "Approval Not
Required"
Requires that efforts be
made to maintain
natural features and
open space
Requires calculations
showing no increase in
peak flow during 100-
year storm
None specified
Requires the
development of a runoff
control plan that
minimizes erosion

None specified
All lots being
subdivided come under
Subdivision
Regulations; lots on an
accepted public way
and with sufficient
frontage are classified
as "Approval Not
Required"
Requires that efforts be
made to maintain
natural features and
open space
None specified
None specified
None specified
None specified
All lots being
subdivided come under
Subdivision
Regulations; lots on an
accepted public way
and with sufficient
frontage are classified
as "Approval Not
Required"
Requires that efforts be
made to maintain
natural features and
open space
Requires calculations
showing pre- and
postconstruction peak
flows and total volumes
for 2-, 10-, and
100-year storms
Requires that storm
water be recharged
rather than piped to
surface waters to the
maximum extent feasible
Requires that an
erosion control plan be
developed for during
and after construction

None specified
  — flow characteristics,
  — tidal elevation in coastal areas, and
  - sediment data.

• Chemical
  - water quality data and
  — sediment data.

• Biological
  - fisheries data,
  - benthos data,
  — plankton data, and
  — biomonitoring data.

• Water quality standards and criteria
  — federal criteria and
  — state standards.

These  data should be gathered to help the  program
team develop a  profile of the conditions in the water
body of concern. Source discharge, water, sediment,
and biological data typically will exist from past studies
of  the watershed.  By gathering  this  information,  a
picture can be developed of existing conditions and data
gaps can be identified.
                                   Sources of Water Resources Data

                                   A wide range of sources of existing water  resources
                                   data can be found at the local, state, and federal levels.
                                   Each  agency  that  has  conducted water  resource
                                   assessments in the study area should be contacted for
                                   its  available  data  and  asked about other potential
                                   sources. As this chain continues, fewer new sources are
                                   identified; diminishing returns indicate when most, if not
                                   all, available  data have been  obtained. The following
                                   paragraphs summarize potential, as well as established,
                                   sources of water resources data.

                                   Local

                                   Many municipal departments listed earlier as potential
                                   sources of mapping can also provide water resources
                                   data from previous studies, wetland or  other permit
                                   applications, or routine water resources  monitoring. For
                                   example, health departments typically conduct routine
                                   monitoring of water resources to protect the environment,
                                   to ensure the safety of recreational swimming areas,
                                   and to manage  onsite sewage disposal  systems or
                                   septic tanks.  Municipal departments  responsible  for
                                   reviewing construction and wetlands permit applications
                                   can track local water quality conditions  as part of local
                                                        36

-------
 water  resource   regulations  designed  to  prevent
 cumulative degradation  of  sensitive resources. Local
 permit applications can  contain recent and historical
 water quality, source discharge, and hydrologic data to
 demonstrate  compliance with  local or state wetlands
 and water quality regulations. Receiving-water data also
 might be available from NPDES monitoring  records,
 which often represent valuable information about the
 effects of a specific pollution source. Also data might be
 available for water bodies in special drinking-water or
 flood-control districts.

 State

 In  most states,  several  agencies  deal  directly  or
 indirectly with  water quality issues, such as water
 resources, pollution control, clean lakes, transportation,
 fisheries, environmental  review, wetlands, and coastal
 zone management. The  agencies might also deal  with
 water quality in terms of  discharge permit applications,
 fisheries status reports, development review, wetlands
 impacts,  and  effects on coastal  resources.  Every 2
 years,  states  prepare two  reports—a  Section 305(b)
 Water  Quality Assessment Report,  summarizing  the
 status  of the  states' waterways,  and  a Section  319
 Nonpoint Source  Assessment Report,  listing  water
 bodies affected by  nonpoint  sources—that  indicate
 sources of  existing water data, programs that address
 NFS  pollution, and  sources  of  agency assistance.
 These reports are  available  from  the  state  water
 pollution  control agency or the EPA  regional  office.
 Information concerning water bodies in the Clean Lakes
 Program (CWA Section  314) also might be available
 from the state.

 Federal

 The federal government  is an excellent  source  of
 hydrology and water resources data through agencies
 such as EPA,  SCS, and  the USGS. Table 4-8 outlines
 a number of major federal government sources of water
 resource data including  water  quality,   hydrology,
 meteorology, biomonitoring, and sediment quality data.
 In some cases, information can be supplied through the
 mail; in other cases, such as the USGS National Water
 Data Exchange, the information can be accessed only
 by using a computer modem.

 Analyzing Water Resources Data

 Existing data  collected by  different  local, state,  and
federal  organizations likely  were  collected  using
 different methods, at different times, and with different
objectives. Each data set  should, therefore,  be reviewed
to assess its  quality and applicability to urban  runoff
pollution  prevention  and  control  program  efforts.
Although the criteria for this assessment should be site
specific, basic considerations include sampling program
Table 4-8.  Federal Sources of Water Resource and
          Hydrology Data
Source
                     Type of Information
U.S. Environmental Protection Agency
Clean Lakes
Program

National Estuaries
Program

Mussel Watch
Program
Ocean Data
Evaluation System

Permit Compliance
System (PCS)
STORET Data


U.S. Geological Survey
Water Resources
Division

Water Quality Branch
                     Water quality and other diagnostic
                     information for lakes monitored under
                     the Clean Lakes Program
                     Water quality and other diagnostic and
                     research data for 21 coastal
                     embayments
                     Monitoring of mussel tissue for heavy
                     metals and other toxic and xenobiotio
                     compounds in areas of wastewater
                     discharges
                     Pollution sources, effluent,  water
                     quality, biological and sediment
                     pollution data
                     Point source discharge data from
                     NPDES monitoring programs
                     Flow and water quality data in receiving
                     waters
                     Flow and water quality data collected at
                     USGS streamflow gaging stations for
                     rivers and streams
                     Receiving waterflow and water quality
                     data, point source data from NPDES
                     monitoring programs

U.S, Department of Commerce
National Climatic        Precipitation data and statistics from
Center                weather-monitoring stations nationwide

U.S. Food and Drug Administration
Shellfish Sanitation
Branch
                     Sanitary survey reports for coastal
                     areas with shellfish habitat. Reports
                     include shoreline surveys for actual
                     potential pollution sources and water
                     sampling data for total and fecal
                     coliform
U.S. Army Corps of Engineers
Reservoir water
Dredging Permit
Application
Program


Other

U.S. Department of
Agriculture,  Soil
Conservation Service

National Oceanic and
Atmospheric
Administration

Federal Emergency
Management Agency
                     Quantity and quality data
                     Water and sediment quality data
                     collected in support of Clean Water Act
                     Section 404 dredge and fill permit
                     applications
                     Sediment data for specific structural
                     controls
                     Marine charts for coastal areas, tide
                     tables, and tidal current tables

                     100-year flood plain elevations
design and quality assurance/quality control (QA/QC).
Data that would be useful in the planning process can
be  entered  into  a  data  base  to  facilitate  data
organization, management, and analysis. One method
is to enter the information into a personal computer-
                                                      37

-------
based standardized  spreadsheet  format that allows
sorting  and  plotting  of the data. Spreadsheets  are
extremely versatile and allow the user to:
* Organize data from multiple sources.
• Analyze data from individual  sampling programs or
  of aggregate data.
• Sort  data,  such as  by  sampling  station location,
  analytical parameter,  or date of collection.
• Statistically analyze data.
• Create x-y  plots of parameter concentration versus
  time or distance.
* Continuously update  the data base.
Table 4-9 presents an example spreadsheet format with
the results of example statistical calculations. Figure 4-1
illustrates an  x-y plot of total suspended solids (TSS)
concentrations  over  time  at the monitoring  station
used in Table  4-9.  More  advanced  applications of
spreadsheets can be used for hydrologic calculations
and  for calculating pollutant loading based on runoff
volumes and pollutant concentrations.  Spreadsheets
can also be used to create data input files for computer
models that help evaluate pollutant concentrations in
receiving waters and effects on water resources and
beneficial uses.
In addition to simple spreadsheet programs for storing
and  organizing data, specialized database management
programs can be utilized. These programs are designed
specifically  for organizing large amounts  of data and
manipulating the data to produce customized reports.
These programs can often produce output for direct use
in analysis  programs, such  as  those discussed  in
Chapter 6. Also, since GIS applications generally use
data bases to store and retrieve data for generating data
layers, a GIS system could be used for analyzing the
existing  water resources data.  In this way, the water
resources  information  can be directly plotted on the
base maps generated during the watershed description
Table 4-9.  Example Water Resource Data Spreadsheet
Station"
45
45
45
45
45
45
45
45
45
45
45
45
45
45
45




Date"
031885
032085
040185
042985
050385
051385
051585
052085
052985
062585
071785
072385
072685
072785
073185




Day0
108
110
122
150
154
164
166
171
180
207
229
235
238
239
243




Timed
0800
1310
1010
1300
1230
1410
2010
1800
1330
0810
2040
0850
1330
1620
1150




Parameter9
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
TSS
Avg
Dev
Max
Min
Concentration,'
mg/L
50
30
800
330
200
20
50
100
40
400
324
930
160
120
450
266.93
272.08
930
20
Flow,9
tfVs
2.1
2
10.5
4.1
2.6
2.3
1.9
3
2.7
2.9
4.3
6.1
2.5
2.9
3.7




Agencyh
uses
EPA
EPA
uses
EPA
EPA
EPA
USGS
EPA
USGS
EPA
EPA
USGS
EPA
USGS




Method1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1




*Tha station number assigned to the collection location during the study; the same physical location may have more than one station number
  for surveys conducted by different agencies.
  Date of the sample collection.
0 Sequential numbering of days starting with the earliest date of data collection.
dTima of the sample collection (HHMM).
"Water quality parameter (TSS = total suspended solids).
1 Mass of constituent per unit volume.
° Volume per unit time during sampling.
. Agency conducting the survey.
1 Analytical method (1 = Standard Method 2540 D).
                                                     38

-------
                        Station Number 45
       1

      0.9

      0.8

   ^ 0.7
 ^1
 if 0.6

 g| 0.5

      0.4

      0.3

      O.Z

      0.1

       0
I
           100  120  140  160  180  200  220  240  260
                          Day Number

 Figure 4-1.  Total suspended solids (TSS) concentrations.

 process,  which allows  the user  to  link watershed
 information, such as land use or soil conditions, directly
 with water resource data.

 The Data Management and Analysis section of Chapter
 5  discusses in more detail presenting and analyzing
 water resource data.

 Contents of a Receiving-Water Description

 After the  water resource data have been gathered, a
 receiving-water  description  must  be  developed  to
 describe the existing conditions of the water body being
 investigated. This description should include summaries
 of the data collected,  organized by  data type  (i.e.,
 physical/hydrologic,  chemical,  biological,  and  water
 quality standards and criteria). Each summary includes
 a  narrative description  outlining  the  information
 gathered for each data type. This information should be
 presented in a way that indicates existing data gaps and
 a priority for addressing those gaps.

 Summary

 This  chapter discusses  the collection of existing
 information to describe the planning area's watersheds
 and water resources. The information collected should
 concentrate on  the  delineation  of watersheds;  the
 description of land uses in the  watersheds; and the
 identification of  related environmental, infrastructure,
 municipal, and  pollution  source  data. The  water
 resource description should present data on physical,
chemical, and biological conditions of  the water body
 along with applicable standards and criteria. Based on
 the  material presented in this chapter, a suggested
 outline  for  the  existing conditions  description is as
 follows:

 •  Project area

 •  Watershed data description
   - environmental data,
   - infrastructure data,
   - municipal data,
   - potential sources/existing BMP data,
   - miscellaneous data,  and
   - data gaps.

 •  Receiving water data description
   - source input data,
   - physical/hydrologic data,
   — chemical data,
   - biological data,
   - water quality standards and criteria,
   - miscellaneous data,  and
   - data gaps.
 •  Summary of data needs

 •  Refinement of goals

 Expending resources at the beginning of the planning
 process "to  locate as mucfi  e^isHng~Tn"formation  as
 possible is cost effective  in the long term, because it
 helps maximize use of existing information, minimize
 data collection costs, and avoid overlooking important
 data resources.

 The information, having been gathered and analyzed,
 has to be examined to determine existing knowledge
 gaps.  If  necessary   information is  unavailable,  the
 program team must  collect additional  data. The next
 chapter discusses obtaining  and analyzing the water
 resource data required to describe existing conditions
fully.

The program team can base site-specific program goals
on the existing conditions information by examining the
general initial goals and refining them. As discussed in
Chapter  3,  a  knowledge of  existing conditions is
important to have before  site-specific  goals  can be
established.

The following case studies provide examples of existing
conditions assessment for water bodies in  Lewiston,
Maine, and Pipers Creek in Seattle, Washington.
                                                   39

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                                      Case Study:
                               City of  Lewiston, Maine,
                CSO, Storm Water, and NFS Planning Program
                         Existing Conditions Assessment


Background

Lewiston, Maine, embarked on a planning program in 1991 to address CSO, storm water, and NPS
pollution issues. Overall aspects of this planning program are described in a companion case study at
the end of Chapter 3. This presentation focuses on the city's efforts to evaluate existing conditions.

The city invested significant time and energy in assembling and analyzing existing information in an effort
to maximize the use of existing data and minimize the need for new data (and the potentially high cost
of collecting it). The  city also wanted a systematic way to sort and analyze information with respect to
the critical pollution control issues. A set of "baseline information" was also desired from which to compare
and assess future program needs and activities.

Existing conditions were assessed using a methodology  similar  to that described in  Chapter 4. A
watershed description, a receiving-water description, and a summary of data needs were prepared. Each
of these components, including the approach and results, is described below.

Watershed Data
The program team,  using the  list of watershed data in Chapter 4, contacted and held meetings with
individuals  who  might  have  pertinent data.  The  list of data compiled is shown in Table 4-10.
Environmental data on the watersheds were generally available from a combination of local, state, and
federal sources, as shown. Infrastructure data were available from the city, who already had accurate
mapping of the major roadways, drainage system, and sewerage system. Municipal data, as well as
data on potential pollution sources and BMPs, were available but required significant effort to compile.

Areas requiring a lot of work—potential  pollution sources, nonstructural controls, municipal  source
controls, and existing structural controls—are described in the following paragraphs.

Potential Pollution Sources
While a number of possible pollution- sources existed within the city's watersheds, they had never been
mapped.  The city compiled extensive information on underground and aboveground storage tanks,
landfills, vehicle maintenance  areas,  salt storage and snow dumping areas, CSOs, and storm drain
cross-connections. These were plotted on a base map, along with watershed  boundaries, receiving
waters, and other important features  such  as gaging stations,  recreational  areas, and flood  control
structures. The map contains  information similar to that required in the NPDES storm water permit
regulations. It provided a convenient way of reviewing watersheds and potential pollution sources within
them, possible threats to receiving waters, and the underlying zoning districts.

Most of the potential pollution  sources exist within the watershed areas of Jepson Brook, Hart Brook,
and Androscoggin River—the most  developed  watersheds.  Stetson Brook watershed has several
potential sources, and Salmon/Moody Brook has almost none. No-Name Brook and Pond watersheds
did not have many source areas. One area of medium-density residential development on Sabattus
Street with a concentration of underground tanks was noted. Located at the brook's downstream portion
near the pond, this area is of concern.

Nonstructural Controls

The city's land use and zoning code and other development guides were reviewed to determine the
status of nonstructural controls. The city was determined to have a comprehensive set of nonstructural
                                            40

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Table 4-10.  Lewiston Watershed Data
Description                        Source
Environmental
Topography
Land use
Recreational areas
Soil and surface/bedrock geology
Vegetation
Natural resources
Temperature
Precipitation
Hydrology
Infrastructure
Roads and highways
Storm drainage system
Sanitary sewer (and combined
sewer) system
Treatment facilities
Other utilities
Municipal
Population

Zoning
Land ownership
Regulations and ordinances
Municipal source control BMPs
Potential Sources/BMPs
Landfills
Waste handling areas
Salt storage facilities
Vehicle maintenance facilities
Underground tanks
NPDES discharges
Pollution control facilities
Retention/detention ponds
Flood control structures
USGS topographical maps; city's 100- and 200-scale maps
Zoning Map Lewiston, Maine, revised 11/7/91; Comprehensive Land Use Plan (1987)
Parks Department inventory
USDA Soil Conservation Service Soil Survey
USGS quadrangle sheets and Maine DOT aerial photos
Comprehensive Land Use Plan  (1987)
NOAA
National Climatic Data Center; four rainfall gauges owned and operated by Lewiston
FEMA flood mapping


Various city maps exist
Record drawings provided by the city
Record drawings provided by the city

Record drawings provided by the city
Gas, New England Telephone maps
U.S. Census data; Maine Dept. of Data Research and Vital Statistics; Comprehensive
Land Use Plan (1987)
Zoning regulations; city zoning map; Comprehensive Land Use Plan (1987)
City Assessor's maps
Draft development permit provided by the city; Comprehensive Land Use Plan (1987)
Interviews with various city departments and staff
Locations developed by city
Locations developed by city
Locations developed by city
Locations developed by city
ME DEP list supplemented by the city
Locations developed by city
Lewiston Area Water Pollution Control Authority
Public Works  Department inventory
Public Works  Department inventory
                                                      41

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controls, which were analyzed and presented in a series of matrices—a convenient tool to assess the
strengths and weaknesses of the regulations.
The major areas of existing regulatory authority include conservation districts, performance standards,
and development review standards. Conservation districts (Table 4-11) are areas in the city that require
special protection. Each district has requirements on the amount of open space or impervious surface
area, on the size of buffer zones where applicable, and for solids control and pollution control.
Performance standards (Table 4-12)  are designed to  control impacts of certain activities (e.g., earth
removal or timber harvesting) in specific areas (e.g., shoreline or flood plains). In  each case, buffer or
filter strips  are required as appropriate. Controls also are specified in most cases  for solids or other
potential pollutants.
Development review standards (Table 4-13) apply to all new developments above certain specified sizes.
The sizes are relatively small so that most  new developments or redevelopments are Covered. These
standards contain a number of general review criteria for storm water management, erosion control, and
other miscellaneous items.
Overall, the controls provide a more thorough and aggressive program than many communities of similar
size have.  The major  area  needing  strengthening was the  control of postdevelopment flows. Most
requirements involved control of a 25-year storm which  is oriented toward flood control. Because smaller
storm events (i.e., 1-year return period or less) typically contribute most of the urban runoff pollutant
Table 4-11.  Summary of Lewlston Nonstructural Controls—Conservation Districts
                            Resource Conservation
                            (RC)
                         Ground-Water
                         Conservation (GC)
                         Lake Conservation (LC)
Scope of regulations
Runoff Quantity Control
Open space
Postdevelopment flow control

Runoff recharge


Additional Controls
Solfds control



Other pollution control
Protects fragile ecosystems   Protects existing and
and areas of unique value    potential ground-water
as shown on city zoning map supply areas
At least 90% open space

Minimum 25-ft stream buffer

Minimum 50-ft shoreline
buffer
None specified

None specified
Earth removal performance
standards apply (see Table
4-12)


Performance standards
apply (see Table 4-12)
Maximum impervious surface
ratio of 0.25
None specified

Specify measures to protect
from loss of recharge
No earth removal below
seasonal high ground-water
table
Prohibits solid waste
disposal, petroleum storage,
deicing chemical storage,
snow dumping, hazardous
waste storage, automotive
repair shops, junkyards,
cemeteries, and land
application of sewage

Ground-water protection plan
required
                         Protects water quality of
                         No-Name Lake
Maximum impervious surface
ratio of 0.1

Minimum 50-ft shoreline
buffer

Increase of <20% for
25-yr/24-h storm
None specified
Submit erosion and
sediment control plan to
minimize sediment discharge
to pond

Prohibits use of fertilizers
within buffers, onsite sewage
disposal within 250 ft

Total lawn and garden area
<30% of lot area

No increase of phosphorus
in pond >one part per billion
for a development
                                                  42

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Table 4-12. Summary of Lewiston Nonstructural Controls— Performance Standards
Shoreline Area Earth Removal Timber Harvesting
Scope of
regulations
All areas within 250' ft of
Androscoggin River and
tributaries and all areas in.
Resource Conservation
District (see Table 4-11)
New earth removal or
expansion of existing
activities
Limits activities
depending on zoning
district
Floodplain
Management
Controls
development within
floodplains
 Runoff Quantity Control
 Open space       75-ft buffer around        Natural vegetative strip at
      i           high-value wetlands       least 50 ft wide must be
                                        maintained around activity
                 Filter strip of varying width  (can be  as High as 100 ft)
              •"  required between road
                 and water body
Postdeyelopment
flow control
Runoff'recharge
Road culverts and. bridges  No net increase in runoff
shall pass 25-yr storm     discharge

None specified           None specified
                         Minimum 50-ft stream
                         buffer

                         Buffer strip required
                         depending on slope

                         Limits on amount of
                         vegetation removed
                         depending on area

                         None specified

                         None specified
Additional Controls
Solids control      No grading or filling on
      '.           slopes >25%

                 All listed activities must
                 prevent erosion and
                 sedimentation     • '  '•
Other pollution
control
Filter strip required near
tilled land

Subsurface .disposal not,
allowed within 100 ft of
water body

Agriculture shall minimize
bacteria and nutrient
contamination
No slopes greater than 2:1    None specified

Erosion prevention plans
including the use of ditches,
sedimentation basins, or
dikes must be used if the
activities are within 250 ft of
a water body
Operation may not cause
harmful leachate

Petroleum or hazardous
waste storage prohibited
Prohibited in resource
conservation district

Limited in shoreline
areas and lake
conservation district
                                                                    None specified
                     None specified

                     None specified
                                                                    Structures must be
                                                                    protected from flood-
                                                                    waters (limits
                                                                    erosion)
Locate sewerage
system to minimize
contamination of
waters
loading on a long-term basis, control of such smaller storm events was recommended. Another area that
could be strengthened is the onsite disposal of storm water. While noted in the development review
standards,  this plan  could be  made  more  specific. Finally, other parts of the  development review
standards could be made more specific with respect to runoff pollution  control.

Municipal Source Controls

Interviews were conducted to summarize the current city "source control" activities (summarized in Table
4-14). Most activities  conducted by the city appeared reasonable with respect to standard practices of
similar sized  municipalities. Areas that appear to need further consideration include cross-connection
removal•,  road salting,  and  household hazardous waste  pickup.  The  city  has  identified  some
cross-connections and plans to implement a removal program. Road-salting policy does  not vary in
sensitive  areas such  as No-Name Pond; such a policy  could be beneficial in the sensitive receiving
waters. Many communities are involved in household hazardous waste pickup programs. Such a program
could prove beneficial and would be consistent with the  city's other aggressive solid waste programs.
Such programs, however, also can be expensive. Further evaluation of municipal BMP/source control
activities is  planned after collection of data and evaluation of various possible BMP programs.
                                                 43

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Table 4-13.  Summary of Lowlston Nonstructural Controls—Development Review Standards

                Storm Water Management      Erosion Control              Other

Scope of         Standards apply to all new subdivisions, residential developments with more than five units,
regulations       nonresldential developments, and numerous other development categories.
Runoff Quantity Control
Open space      Preserve natural drainage ways  Preserve natural vegetation

                                            No fill storage within 50 ft of
                                            water body
Postdevelopment  Must handle 25-yr storm without  None specified
flow control       surcharge
Runoff recharge   Dispose of storm water on the    None specified
                property to the extent possible
                           Landscaping plan required

                           Open space set-asides for larger
                           developments
                           Storm water drainage plan required
                           (25-yr/24-h storm)
                           None specified
Additional Controls
Solids control      None specified
Earth material removal         Erosion control plan required
standards apply (see Table 4-12)

Permanent erosion control
measures within 15 days after
final grading, or use temporary
measures

Use debris basins, silt traps, or
other measures during
construction
Othor pollution    Cannot degrade biological and   None specified
control           chemical properties of receiving
                waters; such controls as oil and
                grease traps, onsite vegetated
                waterways, and reductions of
                dofcing and fertilizers may be
                required
                           Avoid extensive grading and filling

                           No adverse impact on ground-water
                           quantity or quality

                           No undue water pollution

                           No adverse impact on shoreland
Existing Structural Controls

The structural controls installed  in the city within the last few years were inventoried. The information
compiled is summarized in Table 4-15. Few structural controls exist largely because of the limited new
development or redevelopment in recent years. Most of the projects used the 25-year storm required in
current city regulations as the design criteria. As noted in the nonstructural control discussion, inclusion
of smaller events is being considered as an additional requirement.

Most structural controls listed are detention ponds. In one case, subsurface infiltration is used. In another
case, an inlet structure controls flow from the Garcelon bog wetland into Jepson Brook, and thus is not
a development-related  project.  The  summary  indicates that there  is currently no  inspection  or
maintenance schedule for most of the facilities—a shortcoming for the flood-control use of the facilities
as well as if the facilities were to be used to assist in urban  runoff pollution control.

Receiving-Water Data

As shown in Table 4-16, data on  receiving waters or on the major pollution sources to the receiving
waters were limited. Data were available only for the Androscoggin and Little Androscoggin (which feeds
into the Androscoggin River in Lewiston)  rivers. The USGS maintains monitoring stations on both rivers,
and  published data  are available on dissolved  oxygen, temperature,  pH, and conductivity.  Maine
Department of Environmental Protection (ME DEP) has collected grab samples on a weekly basis during
summer, and data on dissolved oxygen, E. coli or fecal coliform bacteria, phosphorus, total Kjeldahl
nitrogen (TKN), nitrate (NO3), ammonia (NH3), and conductivity are available for several years. The most
                                                  44

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 Table 4-14.  Existing Source Controls/Municipal BMPs

 Source Control/BMP            Description
 Street Sweeping

 Frequency
 Equipment


 Catch Basin Cleaning
 Frequency
 Equipment

 Roadway Sanding and Salting
 Sand:Salt Ratio
 Salt used (tons/road mile)
 Special reduced-use zones

 Solid Waste Management
 Residential
 Commercial
 Recycling program

 Composting program

 Other Existing Controls/BMPs

 Household hazardous waste

 Fertilizer and pesticide usage

 Animal waste removal

 Illicit connection identification
 and removal

 Storm drainage system
 maintenance
All roads once a year; downtown, greater frequency
City owns two mechanical and one vacuum sweeper, and leases one mechanical
sweeper
2,750 catch basins exist; about 1,500 are cleaned each year, April through November
City owns a Vac-All catch basin cleaner
6:1
15,000 yd3/yr sand; 3,000 tons/yr salt
None
By city; once a week; downtown areas twice a week; three fall leaf pickups
By commercial haulers
Curbside once a week, newspapers/cans/clear glass; dropoff for all residential as well as
commercial, scrap metals/office paper/magazines and other materials
None; home composting is encouraged by the city
Waste oil dropoff for residents; no other program

None

Dead-animal pickup on roads only; no program to remove animal wastes

No removal program currently in place; some cross-connections have been identified


General maintenance activities use 25% of annual Highway Department staff labor hours
comprehensive set of data available was collected  by International Paper Company relative to its
wastewater discharge upstream of Lewiston. Although the available data do not cover the entire reach
of the Androscoggin River in  Lewiston, significant data on  fisheries  and sediment exist.  None of the
existing data were oriented towards definition of wet-weather impacts in the receiving water. Some of
the ME DEP grab samples were taken during or after storm events, and the bacteria data indicate
elevated bacteria levels during these periods.

Because of the limitations in available data, two major areas of data collection were decided upon. The
first is data on CSO flows, loads, and impacts, required as part of CSO planning efforts by the state.
The second is information on selected city  water resources where no data currently exist. These
programs are described in the following sections.

CSO Data Collection

The CSO data collection program, being conducted in 1993, encompasses two major elements: CSO
and storm water discharges, and receiving waters. Flow and water quality data are being  collected for
several storm events for several of Lewiston's CSO discharges. These data will be used to calibrate a
computer model of the sewer system. Data are also being collected  on several separate  urban storm
drain discharges to identify the quality of storm water discharge to the receiving waters.

Dry- and wet-weather sampling is being conducted at four locations on the Androscoggin River, and at
two along Jepson Brook, where many of the CSOs discharge. Sampling is being conducted over a 2-day
period during and after several storm events. Sampling is also being  conducted during dry weather to
                                                45

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Table 4-15.  Lewiston Existing Structural Controls

Structure
type
"type of
control
Location
Ownership
Receiving
water
Year
constructed
Design
criteria
Land use
Inspection
schedule
Maintenance
schedule
Kensington
Terrace
Phase II
Detention
pond
8-inch orifice
48-inch
orifice stand
pipe
Southerly
side of
Sherebrook
Extension
City of
Lewiston
Tributary to
No-Name
Brook
1990
2-yr and
25-yr storms
Neighborhood
Conservation
"A" and Res
None
None
Turnpike
Industrial
Park
Two
detention
ponds (P1
andP2)
P1: 12-inch
orifice
P2: 18-inch
orifice
P1: North of
Cottage
Road
P2: South
of Cottage
Road
City of
Lewiston
Drainage
ditch to
Hart Brook
1990
25-yr storm
Industrial '
None
None
Chalet
Motel
Detention
pond
8-inch
orifice
Southwest
of Lisbon
Street
Chalet
Motel
Hart Brook
1992
25-yr storm
Highway
business
None
None
Super Shop
'n Save
Underground
piping
detention
system
6-inch by
3-foot 4-inch
orifice
Sabattus
Street and
Highland
Spring Road
Super Shop
'n Save
Tributary to
Garcelon
Bog/Jepson
Brook
1988
25-yr storm
Highway
business
None
None
Sand Hill
Estates
Detention pond
10-inch orifice
Southwest of
Woodille Road
City of Lewiston
Intermittent
stream to
Jepson Brook
1989
Volume = 0.52
acre-feet
Neighborhood
Conservation
"A"
None
None
Andrews
Pond
Small pond
48-inch
orifice
Bates
College,
behind
Olin Arts
Center
Bates
College
Jepson
Brook
Unknown
Not
available
Institutional
Office
District
Unknown
Unknown
Jepson
Brook Inlet
Structure
Inlet control
structure
Concrete weir
East of
Farwell Street
City of
Lewiston
Jepson Brook
1986
Not available
Neighborhood
Conservation
"A"
2-3 times/yr
None
Lewiston
Recycling
Facility
Detention
pond
8-inch
orifice
18-inch
orifice
West of
recycling
center
City of
Lewiston
Tributary
to Andros-
coggin
River
Scheduled
for spring
1993
25-yr
storm
Industrial
N/A
N/A
             Table 4-16.  Lewiston Source Input and Receiving-Water Data
             Description                                 Source
             Source Inputs (Flow and Quality)
             CSO
             Storm water
             Other NPS
             Receiving Water
             Physiographic and bathymetric data
             Row characteristics
             Sediment data
             Water quality data*
             Sediment data
             Rshories data
             Benthos data
             Biomonitoring  results
             Federal standards and criteria
             State standards and criteria
None
None
None


Some available; see water quality data below
USGS flow data
International Paper—Androscoggin River
ME DEP; USGS; CMP; Union Water Power Co.
International Paper—Androscoggin River
International Paper—Androscoggin River
International Paper—Androscoggin River
None
EPA
ME DEP
             * Note: All water quality data in Androscoggin River only.
                                                     46

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 establish background conditions. Data  are being analyzed for several parameters including  E. coli
 bacteria, pH, dissolved oxygen, and temperature.

 Water Resources Data Collection

 Due to the absence of available data, collection of new data was recommended in the major watershed
 tributaries (except for Jepson Brook, which is being sampled as part of the CSO sampling effort) as well
 as in No-Name Pond. The details of the program will be developed after the CSO sampling effort is
 completed in 1993. In general, the program will consist of dry- and wet-weather data collection at various
 stations. Grab sampling is contemplated because the major purpose of this effort is to characterize the
 quality of each water resource.
                                      Case Study:
                     Pipers Creek Watershed Characterization
                           and Water Quality Assessment


The Pipers Creek watershed borders Puget Sound in northern Seattle, Washington. Pipers Creek is an
urban  freshwater stream that drains a 3.5-square-mile watershed. Land use in the watershed  is
approximately 56 percent residential and 12 percent industrial and commercial, with the remaining 32
percent left as open space. Figure 4-2 shows the creek and its watershed.

As part of an overall effort to improve water quality in Puget Sound and its tributaries, an NPS pollution
control plan was developed in 1989 and 1990 by the city of Seattle and the, Washington Department of
Ecology (WA DOE). The purpose of the plan was to develop a program of control measures to reduce
or prevent NPS pollution to Pipers Creek. The plan was 'developed after Pipers Creek was selected by
the WA DOE as one of the state's first early action watershed projects for NPS pollution control. The
plan was funded by the WA DOE through a grant to Seattle.

An early step in action plan development was characterizing the natural and manmade environments in
the Pipers Creek watershed to  help determine the land use practices  and  physical conditions that
contribute to NPS pollution in the watershed. Also, existing water resource conditions were determined
by gathering and analyzing available water quality data for Pipers Creek. The results are summarized
in the "Pipers Creek Watershed Action Plan for Nonpoint Source Pollution: Watershed Characterization
and Water Quality Assessment" (WA DOE, 1990), which includes the data required to develop pollution
prevention and control measures for the Pipers Creek watershed.

The types of watershed and water resources data collected and used in the Pipers Creek characterization,
compared with the types of characterization data recommended for collection in this chapter, are shown
in Tables 4-17 and 4-18. In general, the full range of relevant baseline information was gathered, except
perhaps information that might have been available on  certain potential pollution sources. While some
existing watershed data were found to be available, existing  water resource, sediment chemistry, and
biological data were less complete. Water resource data came primarily from periodic sampling efforts
carried out by the Seattle Engineering Department and the Metro Wastewater Treatment Plant. In
general, samples were collected during dry weather and were collected for bacteria. Some wet-weather
data were also available. The major sources of data were the monthly fecal coliform sampling conducted
                                            47

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Figure 4-2.  Pipers Creek watershed.
                                                  48

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 Table 4-17.   Pipers Creek Watershed Characterization Data
 Watershed Characteristics             Type of Information Included
 Environmental Data
 Topography
 Land use

 Recreational areas
 Soil and surface bedrock
 Vegetation
 Natural resources
 Temperature
 Precipitation
 Infrastructure Data
 Roads
 Storm drainage systems
 Sanitary sewer systems
 Treatment facilities
 Other utilities
 Municipal Data
 Population
 Zoning
 Land ownership
 Regulations
 Ordinances
 Municipal BMPs
 Potential Sources/Existing BMPs
 Landfills
 Waste handling areas
 Salt storage facilities
 Vehicle maintenance areas
 Underground tanks
 NPDES discharges and pollution
 control facilities
 Retention/detention ponds
 Flood control structures
 Description of topography focusing on steep areas subject to erosion
 Detailed discussion of current and projected land use with map showing
 residential, commercial, and recreational uses
 General discussion of recreational lands
 Description of soils and geology with emphasis on  erosion potential
 Detailed discussion of vegetative habitat with maps of watershed
 Discussion of natural resources with maps of watershed
 General discussion indicating average, high, and low temperatures
 Fifteen years of data to calculate rain event durations and intensities

 Description of roadways in watershed
 Detailed discussion including map of major trunk drains
 General description of sewerage system
 Discussion of size and location of treatment plant and outfall
 Not addressed

 Detailed discussion including current and projected  population data
 Description including watershed zoning map
 Description of the amount and location of land publicly owned
 Detailed description of existing regulations and programs addressing potential
 NFS pollution
 Detailed description of ordinances addressing NPS  pollution
 General description of garbage disposal  practices in the watershed

 Not addressed*
 Brief description of existing facilities in the watershed
 Not addressed*
 Not addressed*
 Description of underground tank program and potential extent of problems
Treatment plant discussed but not flows  and loads
Not addressed*
Not addressed*
* These sources may or may not exist in the watershed.
                                                         49

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Table 4-18.  Pipers Creek Water
Receiving Water
Quality Characterization Data
     Type of Information Included
Physlcal/Hydrologic Data
Tidal elevation
Row characteristics
Physlographte/bathymetric
Sediment physical characteristics
Chemical Data
Water quality

Sediment quality
Biological Data
Fisheries
Benthos
General
Other
Quality standards and criteria
     No discussion of tidal influence on Pipers Creek
     No available data on Pipers Creek flow characteristics
     General discussion of physical characteristics
     No physical sediment data available

     Available water quality data from previous studies; data include sediments, metals,
     pathogens, nutrients, and organics
     Some available sediment heavy metal data from previous studies was discussed

     General description of fish populations in watershed
     No discussion of benthic data
     Description of plant and animal life throughout the watershed

     General description of federal and state water quality standards         	
by Metro at two stations in Pipers Creek since 1970 and a source tracing program conducted at 40
stations in Pipers Creek in  1987 and 1988. Some of these sites were sampled fewer than four times
and others were sampled more than 25 times. Other parameters were analyzed only on a sporadic basis.
Available data were summarized in text, tables, graphs, and maps to help develop a profile of existing
watershed characteristics and water resources.  Based  on this information, the  need for collecting
additional water resource, sediment, and biological data was determined. The project team decided that
no additional data collection was needed before developing the action plan (see Chapter 9 case study).
Once the existing conditions of the watershed were defined, the project team conducted an initial analysis
of the NPS pollution problems using the available data. In this  project, problems were defined as:
•  Significant impairment of designated uses.
•  Unfavorable conditions in comparison with similar watersheds.
•  Relatively frequent exceedances of water resource standards.
•  Lack of specific types of data that are necessary to quantify conclusions.
•  Occurrences that contribute to NPS pollution.
Based on this qualitative assessment, the general problems identified included:
•  Bacterial contamination
•  Turbidity, sediments, and other solids caused by erosion
•  Heavy metals
•  Oxygen depletion
                                                 50

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      • Organics from pesticides and petroleum products
      • Nutrients (e.g., phosphorus)

      According to  available wet-weather data, these  problems worsened during rainy weather. The
      assessment concluded that urban runoff is the primary cause of pollution  problems in Pipers Creek.
      More specific evaluations of NPS pollution could not be accomplished with  the available data, and the
      project team proposed collecting additional data in conjunction with the implementation of preliminary
      pollution prevention measures. The areas requiring additional data collection are:
      • Storm-related receiving water and storm runoff quality data.

      • Periodic dry-weather sampling throughout a larger area of Pipers Creek.
      • Flow and tidal data to help  isolate specific sources.

      • General biological sampling to determine the water body's overall health.

      While the lack of such data prevented the project team from recommending  specific structural BMPs to
      address identified pollution sources,  the team determined that a general pollution prevention program
      focusing on municipal,  regulatory, and public education approaches should be implemented as a first
      step. In  addition to these measures, the program team incorporated additional water quality monitoring
      and implementation of structural demonstration projects to collect more data.
References

When an NTIS number is cited in  a reference, that
document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650

Anderson, J.R.  1976.  A  land  use and land cover
  classification system for use with remote sensor data.
  U.S. Geological Service.  Professional paper no. 964.
U.S. EPA. 1992. U.S. Environmental Protection Agency.
  Storm  water quality control in the Merrimack River
  Basin.  U.S. EPA Region 1. Boston, MA.

WA DOE. 1990. Washington  Department of Ecology.
  Pipers  Creek  watershed action  plan for  nonpoint
  source  pollution: watershed  characterization  and
  water quality assessment. Olympia, WA.

Woodward-Clyde  Consultants.   1989.  Santa  Clara
  Valley  Nonpoint  Source Study  Volume  II:  NPS
  Control Program. Santa Clara Valley Water District.
                                                 51

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                                               Chapter 5
                              Collect and Analyze Additional Data
 Urban  runoff pollution  problems are rarely clear cut.
 While  information from  existing  studies  might  be
 sufficient to understand certain issues, new data often
 must be collected before the assessment and ranking
 of problems or the screening and selection of BMPs.

 Because of the diffuse and intermittent nature of urban
 runoff pollution, its characteristics are difficult to quantify.
 Nonetheless, documentation and quantification of pollutant
 characteristics and effects are critical in developing an
 urban runoff pollution prevention and control plan. Data
 collection activities are often the most expensive aspect
 of the urban  runoff planning process. A common pitfall
 in  urban  runoff  programs  is  expending  extensive
 resources on collecting data that turns out  to be of
 limited  value  to the  overall planning. Data collection
 efforts therefore should be carefully  planned with very
 specific objectives given the difficulty in characterizing
 urban runoff:problems. In this way, only data  that is
 necessary and valuable to the program are collected,
 saving scarce program resources for implementation of
 controls.    i

 This chapter describes how to develop a data collection
 program  that  supports  the  urban  .runoff  pollution
 prevention and control  planning process. The chapter
 first outlines  possible  goals and objectives of  data
 collection  and the  general types  of data  required
 depending on  the  program.   Important  factors  in
 developing a data collection program are highlighted,
 including selection of parameters, selection of sampling
 stations, and frequency  of data collection. Planning the
 data collection work is then discussed, including work
 plan  development,   sample  analysis,  and   quality
 assurance/quality  control.  Executing the program is
 then discussed, including sampling techniques for water
 resource, hydrologic,  and rainfall data collection. The
 chapter ends  with a  discussion of management and
 analysis  of  the  collected  data,  including  various
 methods for analyzing and presenting the data.

 Objectives of Data  Collection

The scope of a data collection program for urban runoff
pollution investigations must be site specific. It should
 reflect the data needs determined during analysis of
 existing  conditions in  conjunction with  initial program
 goals identified in the planning process. Data needs
 may focus  on  potential  pollution  sources;  water
 resource problems;  compliance with  local, state, and
 federal regulations;  or other  issues. A discussion of
 typical data  collection objectives at this stage of the
 program follows.

 Assess Existing Conditions

 If existing data are not sufficient to establish current dry-
 or wet-weather conditions, additional data are needed.
 Dry-weather  sampling of water resources could include
 areas affected by  urban runoff  loading  and areas
 upstream of,  and therefore not influenced by, the urban
 runoff discharges in the watershed. It might also include
 sampling of dry-weather base flows entering the water
 resource through creeks, pipes, or ditches which could
 contain illicit connections. In addition to water sampling,
 sediment and biological sampling are particularly useful
 for determining a water resource's relative health, as
 discussed in  the Chapter 6 case study. Also, sampling
 of habitats, wildlife, soils, and other components of the
 watershed might  be  required to  establish existing
 conditions.

 Wet-weather  sampling  can be used to determine runoff
 pollutant  concentrations  and  to  observe  their
 downstream effects. Wet-weather sampling is critical in
 urban runoff  pollution prevention and control planning
 because most of  the  source loadings occur  in wet
 weather.  Sampling of runoff and measurement of flow
 in both sources and receiving waters during a storm can
 be used  to determine the variability of runoff volumes
 and  pollutant loads and to  assess receiving-water
 impacts for a  particular storm. Results from sampling of
 receiving waters during storms can be used to evaluate
the effects of storm water  runoff on ambient water
quality, violations  of  water quality standards, and the
effects of storm water on beneficial uses. Other types
of wet-weather observations could be useful to assess
flow paths, ponding,  areas of erosion, and other wet-
weather conditions in the watershed.
                                                   53

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Retina Problem Identification

Data collection programs might focus on collecting the
additional  information  needed  to  identify  problems
clearly, such as pollutant sources and water resource
impacts, that first were identified during the existing
conditions assessment. These data can provide the
basis for source  identification,  problem  assessment,
and  BMP  selection.  Data  collection  for  problem
identification could again  involve dry- or wet-weather
sampling of sources,  receiving  waters, or watershed
factors.

Calculate Pollutant Loads

Flow  concentration  data  from  sources  of  pollutants
collected in dry or wet weather, as appropriate, can be
used  to  estimate pollutant  loadings and  to  identify
priority pollution sources  and watersheds. Pollutant
loadings may be estimated using numerous methods
ranging from simple to complex (see Chapter 6). These
estimates can be used to evaluate event  or annual
pollutant  loadings  from  the  watershed,  evaluate
resource impacts, and select appropriate BMPs.

Provide Data for Computer Models

Computer models can be used as predictive tools to
assess problems  and  the  potential  benefits  of
alternative  pollution prevention and control  strategies
(see Chapter 6). Quantitative models that are calibrated
and  verified  using  data  from  site-specific sampling
programs can be used to estimate impacts of future
pollution  loadings anticipated under potential control
strategies.  Models quantify pollutant loads as well  as
assess impacts on receiving waters or other ecosystem
components. These models often  require particular
types of input data that  might have to  be collected.
These typically involve dry- or wet-weather source flow
and  concentration data,  but can  also include other
specialized parameters. For example, data on sediment
oxygen demand in the receiving water might be needed
if dissolved oxygen  modeling is a primary concern, or
physical and chemical  characteristics of street surface
solids might be tested  if pollutant buildup and washoff
is to be simulated.

Address Important Pollution Sources  or
Resource Areas

The monitoring program might need to focus on known
or suspected major  pollution sources, to supplement
available data and  confirm the existence of pollutant
loading from a  source.  Pollution sources could  be
either point or nonpoint sources  expected to  be of
particular importance to the program.  The  monitoring
program also might need to focus  on critical resource
areas. Natural  resources that could warrant special
consideration  for  sampling  include  shellfish  beds,
wildlife sanctuaries and refuges, wetlands, coral  reefs,
spawning grounds, recreational fishing areas, bathing
beaches, and drinking-water resources.

Fulfill Regulatory Requirements

Specific  regulatory programs might require collection of
certain data types. As discussed in Chapter 2, programs
such as  the NPDES storm water permit program have
specific  data  collection  requirements.  As  another
example, flow and quality data at CSO outlets might
have to  be collected to  satisfy state  CSO planning
requirements.
Each data collection program should be  developed
based on one or a combination of the above objectives,
or other objectives as  appropriate. Data  should be
collected only  if a specific purpose  relevant to the
program is fulfilled.

Data Collection Programs
Developing a  data  collection  program  depends on
numerous factors.  The  program  should have clear
objectives, as discussed  in the previous section  of this
chapter.   The   program   should   also   reflect  the
goal-setting process described in Chapter 3. Design of
the data collection  program also depends on factors
such as the size and nature of  the watersheds  and
 receiving waters. The plan  must  take  into  account
available funding, resources, and schedule constraints.

This section discusses how to implement urban runoff
data collection programs. First, the major elements of
designing a data collection program, including selection
 of  parameters, sampling  locations,  and sampling
frequency,  are summarized. The  selection  of  an
 analytical  laboratory, laboratory  methods and data
 quality   assurance  procedures are then  discussed.
 Finally,  the chapter  discusses  how  to  conduct the
 sampling program, including water sampling, sediment
 sampling, and hydrologic and rainfall monitoring. Some
 of the   numerous,  detailed  technical references  on
 monitoring that this  handbook  is  not attempting to
 reproduce are included in Appendix A.

 Designing the Data Collection Program

"Since data collection programs are site specific and
 varied,  providing detailed guidance on  what  should
 "typically" be done is not realistic. This chapter opens
 with an overview  of the  type  of objectives  often
 established.  The  major  considerations  in design of
 a   data collection   program—parameter  selection,
 sampling station selection, and the frequency of data
 collection—are presented in this section.
                                                  54

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Selection of Parameters

Parameters  to  be  measured  during  the sampling
program should be  selected  based on the review of
existing  conditions;  the program's overall goals;  the
specific objectives of the data collection program; and
the requirements of local, state, and federal regulations.
For example, most state water quality standards have
numeric limits for indicator bacteria levels in waters
intended for swimming and boating. If local beaches are
threatened by bacterial contamination from storm water
or CSOs, bacteria sampling needs to be included in the
program.

Given the long list of potentially important parameters,
site-specific  considerations   drive  the  selection  .of
parameters to be tested. The most common pollutant
categories associated  with  urban runoff  are  solids,
oxygen-demanding matter, nutrients,  pathogens, and
toxic  substances  as  discussed  in  Chapter  1.  The
sampling  plan  may  include  analysis  of  specific
parameters  included  in  these  or  other  pollutant
categories (see Table  1-3).  Table 5-1 lists the most
commonly identified priority pollutants in the Nationwide
Urban  Runoff Program (NURP). Specific  pollutant
Table 5-1.  Priority Pollutants in at Least 10 Percent of
          Nationwide Urban Runoff Program Samples (U.S.
          EPA, 1983a)*
                            Table 5-2.  Storm Water Sampling Parameters (U.S. EPA, 1991a)
Metals and Inorganics
Antimony
Arsenic (50%)
Beryllium
Cadmium
Chromium (60%)
Copper (90%)
Cyanide
Lead (95%)
Nickel
Selenium
Zinc (95%)

Pesticides
Alpha-hexachlorocyclohexane
Alpha-endosulfane
Chlordane
Lindane
Halogenated Aliphatics
Methane, dichloro

Phenols and Cresols
Phenol
Phenol, pentachloro
Phenol, 4-nitro

Phthalates Esters
Phthalate, bis(2-ethylhexyl)

Polycyclic Aromatic
Hydrocarbons
Chrysene
Fluoranthene
Phenanthrene
Pyrene
* Frequency of detection in parentheses when 50% or greater.

parameters are required for characterizing storm water
as part of an NPDES permit application for a municipal
storm sewer system discharge (Table 5-2).

Based on  more recent data  than NURP's, the most
commonly detected  organic compounds are shown in
Table 5-3 (U.S. EPA, 1990a). In this same study, seven
metals (aluminum, cadmium,  chromium, copper, lead,
nickel, and zinc)  were  tested for  both filtered  and
Sediments/Solids
Total dissolved solids (TDS)
Total suspended solids (TSS)
Bacteria
Total conforms
Fecal conforms
£ co//
Enterococci
Fecal streptococci
Nutrients;
Total phosphorus
Dissolved phosphorus
Total nitrogen
Total ammonia
Organic nitrogen

Other
pH
Cyanide
Biochemical oxygen demand
(BOD)
Chemical oxygen demand
(COD)
Metals
Antimony
Arsenic
Beryllium
Cadmium
Chromium (total)
Chromium (hexavalent)
Copper
Mercury
Nickel
Selenium
Silver
Thallium
Zinc

Organics
Volatile organic compounds
(VOCs)
Base/neutral and acid
extractable compounds (BNAs)
Pesticides/PCBs
Phenols
Oil and grease
                            Table 5-3.  Detection Frequencies of the Most Frequently
                                      Occurring Organic Compounds (U.S. EPA, 1990a)
Organic Compound
1 ,3-Dichlorobenzene
Fluoranthene
Pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(a)fluoranthene
Bis(2-chloroethyl)ether
Bis(chloroisopropyl)ether
Naphthalene
Chlordane
Benzo(a)anthracene
Benzyl butyl phthalate
Phenanthrene
Frequency of Detection, %
23
23
19
17
17
17
14
14
13
13
12
12
10
                            unfiltered fractions from numerous source areas (i.e.,
                            roofs,  parking  areas,  storage areas, streets, loading
                            docks, vehicle service areas,  landscaped areas, and
                            urban creeks). Detection frequencies were very high for
                            every metal tested in the unfiltered samples.

                            The information in Tables 5-1 through 5-3 can be used
                            as  a  starting  point and  can be  refined  to  reflect
                            program-specific needs. Other conventional parameters
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such as temperature, dissolved oxygen, turbidity, and
specific conductivity  can  be included as indicator
parameters to support specific assessments of urban
runoff pollution sources and receiving waters. It is also
important  to  characterize  particle settling velocities,
particle diameters,  and  dissolved and nondissolved
chemical  fractions  for   use  in  evaluating  runoff
treatability and pollutant routing in the watershed and
receiving waters.
In addition to the source and receiving-water quality
parameters outlined above, sediment samples may be
analyzed for  physical and chemical parameters, such
as grain size  distribution, organic content, total organic
carbon (TOG), nutrients, metals,  petroleum products,
polychlorinated biphenyls (RGBs), or other parameters.
As pollutants  are partitioned between the dissolved and
particulate  phase,  sediment  chemistry reflects the
portion of the particulate-bound  pollutants that settle.
These pollutants  can, through  other  physical  and
chemical mechanisms, be introduced  into the water
column.  Sediment chemistry can indicate potential
pollution problems caused by the sediments, such as
the release of metals and other pollutants into the
water column and the depletion of overlying dissolved
oxygen (DO) as organic matter is  broken down by
microorganisms.
The sediment  characteristics  reflect  the  long-term
effects  of intermittent  and  variable  urban  runoff
discharges. These long-term effects could be  more
significant than short-term water quality variations that
occur in response to individual runoff events. In fact,  it
is easier and more cost effective to test sediments and
plant and animal populations in the affected areas than
to conduct sampling of the intermittent pollution sources
and receiving-water responses. The existing substrate
and communities integrate the cumulative effects and
can be characterized rapidly since they do  not vary
extensively.  Numerous  runoff  event  samples are
necessary to obtain  reliable statistics,  however, and
such data gathering is expensive and time consuming.

Sampling of aquatic biota involves collecting biological
species from the water column and  sediments  to
determine  the  species  diversity,  dominance,  and
evenness. This  process  can include sampling for
plankton, periphyton,  macrophyton, macroinvertebrates,
and fish and determining the number and density of
populations in the water resource. In addition, physical
habitat indicators, such as substrate and plant types
and  conditions,  are  useful  indicators of  pollution
impacts. As  with sediment, these habitats reflect the
long-term  effects of the  intermittent urban   runoff
Impacts. These effects might be subtle and take a long
time to occur, depending on the nature of the transport
mechanisms  and receiving-water body.
Toxicity test sampling can  be used to determine the
relative toxicity of storm water runoff from a conduit,
creek, or other  flow stream that might be receiving
contaminants. Toxicity testing, an integral part of the
NPDES  point source monitoring program, has been
included in  several states' storm  water permitting
programs. Toxicity test results also provide information
on  the relative degree  of  chronic and acute toxicity,
which again reflect the period of exposure of organisms
to toxic effects. A thorough discussion of toxicity testing
can be found in the Technical Support Document for
Water Quality-Based Toxics Control (U.S. EPA, 1991b).

Selection of Sampling Stations

Sampling stations should be selected strategically so
that data collected from a limited number of stations
satisfy multiple sampling objectives. The major types of
sampling are watershed-based (urban runoff sampling)
and water resource-based (receiving-water and aquatic
ecosystem sampling).

Urban Runoff  Sampling.  Wet-weather  generated
discharges (e.g.,  storm water, CSO, and NFS)  can
contribute  large  pulses of pollutant  load  and could
constitute  a significant  percentage  of  long-term
pollutant  loads  from   urban and  suburban areas.
Wet-weather sampling  can  be  used to characterize
runoff from  these discharges, determine  individual
pollutant source and total watershed loadings,  and
assess  the  impact on  receiving  waters.  Pollution
sources,  tributaries,  or entire  watersheds  can  be
ranked  by total  pollutant  load and prioritized  for
implementation  of pollution prevention  and control
measures (see Chapter 6).

In selecting a site for urban runoff sampling during wet
weather, the  following criteria should be considered:

• Discharge volume:  Select sites that  constitute a
  significant  portion of the flow from a watershed.

• Pollutant concentrations: Based either on historical
   information or on land  use or population density,
  select sampling  sites to quantify representative or
  varying pollutant load sources.

• Geographic location: Select sites that permit sampling
   of flows from major subwatersheds or tributaries to
   permit isolation of pollutant sources.

• Accessibility: Select sites that allow safe access and
   sample collection.

• Hydraulic conditions: Utilize existing flow measurement
   devices, such as weirs or gaging locations, or sample
   where hydraulic conditions are conducive to manual
   or automated flow measurements.

Sampling should also  include dry-weather flows from
storm drains or other structures to determine  if  they
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 result  from illicit connections, or from ground-water
 infiltration.  The  magnitude  of  these  dry-weather
 discharges determines the need to identify and remove
 these  illicit  connections. Detailed  procedures for this
 have been developed (U.S. EPA, 1993).

 Water Resource Sampling. For the impact of urban
 runoff  to  be assessed, the  water  quality  of receiving
 waters during normal  dry-weather periods should be
 known. Water quality data collected during dry-weather
 conditions provide  a  basis of comparison to data
 collected  during wet-weather conditions.  These data
 are  also  needed to  quantify dry-weather  pollutant
 transport  from tributaries and ground-water flows. If
 existing data are not sufficient to characterize current
 conditions,  stations  should   provide  good  spatial
 coverage  within the receiving waters. Based on initial
 sampling  results, the  number of  stations potentially
 could  be  reduced. For example,  if initial sampling
 results show  that  a  particular  stream  within  a
 watershed is of high quality, sampling coverage of this
 stream could be reduced. Additional stations could be
 added in  response to  expected changes  in land use
 (such  as  high-density  development  projects), which
 might  affect water quality.  Critical stations, however,
 such as those that previously indicated water quality
 violations, need to be maintained. Also, use of existing
 stations from other programs should be maximized.

 Wet-weather sampling stations should  be located to
 assess impacts of significant urban runoff pollutants and
 major storm drain systems and CSO outfalls. Receiving
 water  stations   should  include  the   dry-weather
 monitoring stations for  comparison. Additional stations
 may be sampled within tributaries affected by storm
 water,  CSO, or other discharges and land use types of
 particular concern.

 Other general site selection criteria for receiving waters
 include:
 • History of available data

 • Easy accessibility
 • Safety of personnel and equipment

 • Entry points of incoming sources or tributaries
 • Adequate mixing of sources or tributaries
 • Straight reaches, rather than bends

 Sediment Sampling.  Sediments in  receiving waters
 affected by urban runoff integrate the long-term effects
 of dry- and  wet-weather discharges because of their
 relative immobility.  Grab samples can be taken to
 indicate historical accumulation  patterns.  Sampling
sites could be distributed spatially at points of impact,
 upstream  (or downstream) reference sites, areas of
future  expected changes, or other areas of particular
interest. Selection of  specific locations is subject to
accessibility, hydraulic conditions, or other aforementioned
criteria.

Biological  Sampling.  Benthic or  bottom-dwelling
organisms are affected  both  by contaminants in  the
water  column  and through contact  or ingestion  of
contaminated sediments. The type, abundance, and
diversity of these benthic organisms thus can be used
to  investigate  the presence,  nature,  and  extent  of
pollution problems. Comparisons of areas upstream
and downstream  of  a  suspected pollution source
require that  sampling locations  have  similar bottom
types,  because physical  characteristics affect both the
chemical composition as well as the habitat requirements
of organisms.

Regional  data  or indices  might  be available  for
comparisons with local  site conditions to determine
whether an ecosystem is stressed.  An  example of the
use of ecoregional data and biotic indices is presented
at the end of Chapter 6. Such data provide a reference
for comparison and might suggest appropriate habitat
types or areas to sample  in determining the level of
pollution impact.

Frequency of Data Collection

The frequency of data collection significantly affects
program cost and should be  determined  judiciously
based  on  the need  for sufficient data  to develop
statistically   valid   conclusions.   Information   on
determining valid  sampling frequencies is available
(U.S. EPA, 1983b). Wet-weather runoff sampling is often
limited to several  events and selected representative
subwatersheds  because   of   the  large   resource
requirements  and  high  costs.  Data  must  then  be
extrapolated to other  similar subwatershed areas and
used to calculate storm-related pollutant loading for an
entire watershed.  Depending  on the area's size and
number of watersheds,  and  on financial  resources,
adequate characterization of storm water runoff from
different watersheds might require a phased approach.
Areas  of  most  concern   are  sampled  first,  with
subsequent sampling to characterize other areas based
on  a watershed priority sequence.  Given the cost of
such sampling, collection of sediment and ecosystem
data that integrate the long-term effects of urban runoff
may be fruitful  since they are relatively stable and do
not need to be characterized as frequently.

For water resources monitoring, the sampling schedule
should account for seasonal climatic changes as well
as  seasonal land  use  activities,  such as  fertilizer
application in spring, or road deicing activities in winter,
that might influence water quality. In temperate areas
with pronounced seasonal changes, monitoring stations
are  usually  sampled  at  least  seasonally.  This  is
especially important for sampling of aquatic biota. For
characterization  of  urban  runoff  sources,  several
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sampling  events  are  ordinarily  scheduled  during
worst-case conditions: In spring during snowmelt and
heavy rains when runoff and contaminant transport is
significant, or during summer conditions when streamflow
is low, receiving-water dilution is minimal, and contaminant
concentrations are potentially highest. In addition, the
relatively high temperatures in summer can affect
aquatic biota, as well as reduce the capacity of water to
maintain  high  DO  levels  and  stimulate  bacterial
metabolism,  placing additional demand  on  oxygen
supplies in the water column. This scenario represents
worst-case conditions in  areas that experience organic
and nutrient enrichment. In areas with fairly constant
climate,  less emphasis is placed on seasonality, with
perhaps more attention placed on land use activities.

After the implementation  of BMPs, additional data might
be   collected  to  assess their effectiveness.  Data
collection after BMP implementation is discussed  in
Chapter 9.

Planning the Data Collection Program

After the data collection program is designed, more
detailed planning and preparation is necessary. This
planning includes development of a data collection work
plan, selection of analytical laboratories and  methods,
and organization  of the necessary staff  and equipment
resources.

Quality Assurance/Quality Control
The  sampling  program should  include a  Quality
Assurance Project Plan (QAPP) to ensure the collection
of meaningful and cost-effective data. An EPA guidance
manual,  Interim  Guidelines and Specifications  for
Preparing Quality Assurance Project Plans (U.S.  EPA,
1983a) is designed to help EPA and  its contractors
prepare  QAPPs. Another   EPA  document,   entitled
Guidelines for Preparation of Combined Work/Quality
Assurance Project Plans for Environmental Monitoring
(U.S. EPA, 1984), combines a work plan with revisions
to the QAPP format and includes a  generic plan. The
elements of this plan, listed in Table 5-4, are discussed
below.
Title  pages  of  QAPPs should  include  places  for
signatures  of personnel  with  approval  authority.
Municipal programs may  use this format for approval by
the project manager or  other responsible individuals.
Additional information could include  project name,
requestor, date of request, and date of initiation (U.S.
EPA, 1984).
The project description is intended to define the goals
or objectives of the project and how the plan will satisfy
those objectives. A subsection on data usage identifies
the  recipients of  the  data and  establishes  their
requirements, thus ensuring that the plan will  produce
Table 5-4.  Typical Combined Work/Quality Assurance Project
          Plan (Adapted from U.S. EPA, 1984)

 1. Title page

 2. Table of contents

 3. Project description
   A. Objective and scope statement
   B. Data usage
   C. Monitoring network design rationale
   D. Monitoring parameters and frequency of collection
   E. Parameter table

 4. Project fiscal information (optional)

 5. Schedule of tasks and products

 6. Project organization and  responsibilities

 7. Data quality requirements and assessments

 8. Sampling procedures

 9. Sample custody procedure

10. Calibration procedures and preventive maintenance

11. Documentation, data reduction, and reporting

12. Data validation

13. Performance and system audits

14. Corrective action

15. Reports
usable  and  effective  data.  A  description  of  the
monitoring network includes sampling site locations and
the  rationale for their  selection. A subsection  on
monitoring parameters and frequency includes a list of
the types of samples to be taken at each site and how
they will be collected. These parameters are then listed
in a table that includes the number of samples, sample
matrix (e.g., water and sediment),  analytical method to
be used by the laboratory, sample preservation method,
and sample holding time.

Fiscal information as to projected costs for sampling
labor,  equipment   and   supplies,  analyses,  and
requirements  for outside  support  may be  included to
support  a budgetary  analysis of the  project.  This
information  will  ensure  that available  resources are
adequate and  properly  allocated to  maximize  the
project's  effectiveness.

One section details the schedule for the project from the
conceptual stage through the  completion  of the final
report. This  schedule aids in assessing the availability
of resources  and  arranging for  outside  support. A
following  section details the project organization and
identifies individuals responsible for the various aspects
of the project, as well as other outside support.  An
organizational chart is frequently included.

Data  quality requirements  (frequently  subject  to
regulatory and budgetary constraints) are  determined
through input from data users, samplers, and analytical
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 personnel and focus on the data needs of the program.
 Objectives should be established  prior to development
 of a work plan. The objectives include the required level
 of detection, analytical precision (repeatability of a set
 of measurements), and accuracy  (agreement of result
 with  true value) obtained  from  analytical  results.
 Accuracy and precision are identified through the use
 of  performance  standards,  analytical  spikes  and
 surrogates, method  blanks, and replicate samples.
 Many of these approaches are parameter-specific, as
 are  the  acceptance  criteria.  These considerations
 should  be discussed  with  the analytical  support
 personnel for the parameters to be sampled. Acceptable
 criteria for various analytical methods are listed in the
 federal regulations (40 CFR 136, Tables  A and B).

 Other  quality   assurance  considerations   include
 representativeness (whether the  collection samples
 represent  conditions and  matrices that support the
 program's objectives), comparability  (whether  the
 analysis  results  can be  compared with other data
 bases), and completeness (whether the  valid data
 obtained  satisfies the program's objectives).  These
 considerations are basic  to the  development  of the
 sampling  plan, and are used to assess the success of
 sampling efforts.
 Detailed   sections  follow  in  the combined  Work
 Plan/QAPP that describe  sampling procedures and
 documentation of sample custody, equipment calibration,
 and  data  handling.  Sampling procedures  can  be
 generally  described,  citing method-specific  references
 such as Standard Methods (APHA, 1992) for detailed
 sampling considerations. Sample documentation typically
 employs  a chain-of-custody form that describes and
 follows the transfer of each sample bottle. Every time
 responsibility for the samples is transferred, signatures
 are  used  and   copies  retained  to  document  the
 transaction. Equipment logbooks  are maintained to
 document maintenance, calibration, and repairs. Data
 documentation includes provisions to meet the needs of
 legal or scientific challenges to the data, as well as
 quality control over  data  entry,  transfers,  and any
 calculations performed.

 The  remaining sections of the combined work/QAPP
 are used to document procedures to validate data, to
 record performance  of  laboratory  personnel and
 equipment, to record steps for corrective  action, and to
 note reporting requirements. Data validation consists of
 an objective review of the data base generated by the
 project against criteria established prior to sampling,
 including holding times, detection  limits, and QA/QC
 results for accuracy and precision. Performance  audits
are done  prior  to making  arrangements  to ensure
laboratory capabilities, as well as during the program to
identify problems  and institute corrective  actions if
 required. Corrective action  provisions define  how to
 proceed in the event that QA/QC objectives are not met.
 Reporting requirements include interim progress reports
 to management personnel to document the status of the
 project, as well as a final report that presents the results
 and conclusions  of the study, including a summary of
 QA/QC performance.

 Analytical Laboratories

 Before  undertaking  the  data  collection  program,
 arrangements  must be  made to have  the samples
 analyzed by a laboratory. If the laboratory analyses are
 not conducted  inhouse, or if an appropriate laboratory
 is not already under  contract to the municipality,  a
 service contract  can  be developed with an  outside
 laboratory that specifies the number  of samples, the
 price per sample, the  analytical methods to be used,
 and a QA/QC plan.

 A laboratory should be selected based on a number of
 criteria, .including  price, analytical  capability,  past
 experience,  reputation,  and  certification.  In  most
 instances,  laboratories that are state  certified for
 specific  chemical  analyses should  be  used. The
 laboratory should be familiar with the type of sampling
 program and the schedule. This familiarity facilitates
 development of a scope of  services, which, in turn,
 helps  ensure  quality  data  and  timely  results. The
 laboratory should be  asked  to provide  a list of past
 clients as references.  The laboratory should have  a
 strong QA/QC program and sufficient capacity to handle
 the  volume and  types of  samples generated by  a
 multifaceted  sampling program.  Because  of  the
 unpredictable   nature  of  storms  for  wet-weather
 monitoring programs, the laboratory must be available
 to receive samples on short  notice, including at night
 and  on weekends, and to perform analyses within the
 required  holding times.

 Other important steps in selecting a laboratory include
 comparison of  costs per analysis or per  sample, and
 evaluation of savings through volume discounts for the
 large number of samples  that  might be generated,
 especially during wet-weather  sampling. Turnaround
 time for  data submittal and the form of deliverable
 offered are additional considerations. A turnaround time
 of 3  weeks is  considered reasonable  for  typical
 analyses for nutrients, solids, and bacteria.  Some
 laboratories can submit results in digital format so that
 it can be directly  inputted to a database management
 system. Many laboratories can supply bottles and other
 equipment, such as coolers,  for the preservation and
transport of samples and courier service for sample
pickup. Such details should  be clearly communicated
before finalizing the contract for analytical services.
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 Analytical Methods

 Of the  many  analytical  methods  to  determine the
 pollutant concentration   in  water  and  sediments,
 standard methods  for  water and wastewater,  as
 published  in the  Federal  Register  and  Standard
 Methods for the Analysis of Water and  Wastewater
 (APHA, 1992), usually achieve the desired objectives of
 the program. The laboratory can modify these methods
 based on the type of sample and the level  of detection
 required.  For   example,  storm   water  pollutant
 concentrations might be significantly greater than those
 diluted by  receiving water;   therefore, methods  for
 analysis of pollutants in storm  water might require less
 sensitivity than methods used to analyze drinking water.
 Other particulars  of the  type of sample (e.g.,  salt
 water or fresh water) might dictate  the  analytical
 method or sample preparation requirements for certain
 parameters, such as metals. The desired detection limit,
 or the lowest concentration that can be reliably detected
 In a  sample, should be  determined in advance.  As
 mentioned,   the  Standard Methods  text  provides
 complete documentation  of  applicable methods  for
 physical, chemical, and  biological  analysis. Specific
 guidance on the analysis of pollutants as required under
 the  NPDES  program  is provided in  the  federal
 regulations (40 CFR 136.3, Tables lAthrough IE). These
 guidelines establish  standard  analytical  methods,
 detection limits for all parameters, and the volume of
 sample required.

 Organization of Resources

 Resources required for  the  data  collection  include
 personnel and equipment. Personnel should be familiar
 with their roles and responsibilities as  defined in the
 work plan and  the team leader and each crew  chief
 should visit the sites in advance.  A health and safety
 plan should be prepared which identifies the necessary
 emergency procedures and safety equipment. Special
 training  might be required, particularly if potentially
 hazardous chemicals are involved, or if confined space
 entry (into manholes, for example)  is required. The
 Occupational Safety and Health Administration (OSHA)
 sets forth requirements for worker safety and protection
 while conducting such work.

 Equipment also must  be  prepared in advance: An
 inventory of  all the necessary equipment should  be
 taken; all equipment to be used in the  effort, such as
 boats, motors, automobiles, and batteries, should  be
 checked; field monitoring equipment should be properly
 calibrated and tested.

 Specific sampling logistics vary with the objectives of
the program. For example, dry-weather sampling can
often  be conducted during daytime  work hours in an
 unhurried manner, though sampling must be scheduled
appropriately to coincide with diurnal,  tidal, or other
variations of importance to the program. By contrast,
investigations of  wet-weather  impacts  in  a  large
sampling program could require several teams who can
mobilize with only a  few hours  notice to conduct
concurrent sampling at several  locations. Receiving-
water sampling could frequently include sampling for
several days after the rainfall  event to assess the
residual effects of urban runoff pollutant loads.

Wet-weather sampling requires thorough planning and
rapid mobilization to implement an effective  sampling
program.  It also  requires  specific  and  accurate
weather information.  Local  offices of the American
Meteorological  Society can provide a list of Certified
Consulting  Meteorologists who provide  forecasting
services specific to the needs of a sampling  program.
Radar contact  can also  be established for  real-time
observation   of  conditions.  If a  sampling  criterion
requires a minimum of 0.5 inches of rainfall because of
resulting CSO  discharges, additional  insight Into the
timeframe of heaviest rainfall can be developed. While
incurring an  additional cost, these efforts could result in
significant savings in costs associated with false starts
and unnecessary laboratory charges.

The rainfall,  darkness, and cold temperatures that often
occur when conducting wet-weather field investigations
render even small tasks difficult. Contingency planning
and  extensive  preparation,   however,  minimizes
mishaps  and  helps  ensure  safety.  Prior  to  field
sampling,  all equipment should be organized, sample
containers should be assembled, and the bottle  labels
filled out to the extent possible. Labeling is best done
by writing directly onto the sample bottle with permanent
markers. If stick-on labels are used,  they should be
waterproof and  secured  with clear  tape. The  label
should indicate the sampling  event (e.g., storm #1),
station location or number,  sample number, preservative
used, and the parameters for which the sample is to be
analyzed.  The sample  number is the most important
identifier, and should be unique to each sample.

Conducting the Data Collection Program

A comprehensive  data collection program with both
source and receiving-water sampling can consist of dry-
and wet-weather monitoring  including water quality,
sediment,   and  sampling of  aquatic  biota;   flow
monitoring;  and   rainfall  monitoring.  This  section
describes the common types of sampling used for urban
runoff programs.

Water Sampling

Sampling  as part of an urban runoff control  program
primarily involves collecting water samples, preserving
them, and transporting them to a laboratory with as little
change in character as possible. Certain parameters,
including temperature, pH, and dissolved oxygen, are
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measured in the field (in situ) because values for these
parameters can change substantially if measured from
a sample of water that has been disturbed of held for a
long time. These parameters  are  usually measured
using battery-powered instruments with probes placed
directly in the water; results are taken from a digital or
analog readout and values are recorded in a field
notebook.

For  samples  undergoing  laboratory  analysis,   the
volume of sample required by the laboratory should be
considered. In addition, accurate measurement of many
pollutants requires  specific  sample container  types,
container cleaning or other preparations, or specialized
collection techniques.  After collection, sample bottles
should be placed in a cooler with bagged ice or reusable
ice packs. Glass bottles should be separated by plastic
bottles or packing material to prevent breakage during
transport to the laboratory. Documentation of analytical
methods, volume requirements, containers, preservatives,
and maximum holding times is provided  in the federal
regulations (40 CFR 136.3,  Table II),  and detailed in
such documents as  Standard Methods (APHA, 1992).

Sampling for water chemistry can involve a number of
approaches. The following terminology is referred to:

•  Grab   sample:  Samples  collected  manually  and
   analyzed individually.

•  Discrete sample: Individual samples collected at
   specific times collected manually or  automatically,
   often combined to create a composite  sample.
•  Composite sample:  Samples combined based on a
   predetermined formula involving flow weighting, time
   interval, or other approach.

•  Automatic sample: Samples  collected. using  an
   automated sampling device.

Grab samples usually  are analyzed individually to
characterize conditions at the time  of  sampling. Many
parameters, such as nutrients and  metals, may be
composited, but attention must be paid to preservative
requirements. If sampling protocols permit and program
objectives  are  satisfied,  composites  represent a
cost-effective approach to quantifying pollutant loads by
reducing the number of samples submitted for analysis.
Other analyses, including bacteria, oil and grease,  and
volatile   organic  compounds  (VOCs),  cannot  be
composited and individual grab samples must be used.
Urban   Runoff   Sampling.   During   wet-weather
sampling, water samples may be taken manually or by
automatic samplers  installed at  the sampling  site
before  the   rainfall.  Automatic samplers  may  be
installed in  manholes  to  sample storm  water or
combined sewer systems, or placed in enclosures next
to creeks or culverts  to sample runoff.  They can be
controlled by flow-measurement devices, by stage height
monitors,  or by timers,  permitting comprehensive
sampling of flow quality with minimal labor.
Automatic samplers may be  used to collect discrete
samples  into individual  bottles  at  predetermined
intervals of  time or flow rate, or to collect discrete
samples and automatically composite them directly into
one container using a pre-set formula. The option of
using discrete or composite sampling is dictated by the
objectives of the program and the parameters to be
measured.  Automatic sampler  units can be either
purchased, leased, or furnished as part of a contractor's
service.
Wet-weather sampling must  be  performed  by two-
person teams to reduce the time required to sample
each station and  for safety reasons. Typically, one team
can sample  at least two stations if the stations are in
close proximity.  Because  of the  typical rapidity of
rainfall-runoff responses, however, the area that can be
covered is  limited.  One  team member  typically fills
sample  bottles   while   the   other  performs  flow
measurements and  records relevant information  in a
field book, including station number, time, date, weather
conditions  (e.g., rain  intensity,  wind  intensity  and
direction), and other observations, such as oil sheens,
odors, or the presence of foam.
Proper  characterization  of urban runoff, either by
manual or  automated  sampling, requires  periodic
sampling of the flow stream. This sampling should begin
with the pre-storm condition, if possible, followed by the
"first  flush," when rainfall  first  washes  accumulated
contaminants from the surface of the watershed and
pollutant  concentrations  are highest,   and  should
continue through the duration  of the rainfall event.
Storm  water   pollutant   loadings  can  then  be
characterized using discrete  samples taken  over the
course of the storm,  or  by creating a flow-weighted
composite based on  the  relative flow rate  (or other
appropriate  parameter) associated with  each sample
taken. Flow  measurement methods and an example of
flow-weight composited data are discussed later in this
chapter.
Receiving-Water Sampling. Sampling   of  receiving
waters to provide background water quality data and to
assess impacts from  urban runoff pollutants  could
range from manual collection of bacterial  samples from
a stream to a full-scale oceanographic investigation of
a harbor  using  a  sizable vessel and  considerable
logistics. The important considerations are to sample
the  parameters  of concern  using proper  sampling
techniques (i.e.,  USDI, 1984;  U.S. EPA,  1982;  Plumb,
1981; APHA, 1992).  Further references are cited in
Appendix A.
                                                  61

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Other considerations for sampling are specific both to
the program objectives as well as to the sampling
station location  characteristics.  For  example, while
surface sampling of shallow, well-mixed systems, such
as  streams, is  adequate to  assess water  quality,
additional samples of a cross  section of wider rivers
might be necessary to meet study objectives.  Deeper
systems subject to stratification from salinity or thermal
conditions  should  include  some form  of  vertical
sampling, which could entail samples taken separately
from several depths analyzed individually or composited
to yield one sample. Such a case requires the use of
sampling devices such as Kemmerer or Nansen bottles
which can be lowered to the desired depth and tripped
by a weight dropped from the surface to produce a
discrete sample. Instruments for in situ sampling of pH,
temperature, dissolved oxygen, or salinity also can be
lowered  to specified  depths,  with  measurements
transmitted to the surface by cable and recorded.

Sediment Sampling

Analysis  of sediment chemistry data can indicate the
historic water quality. Water column contaminants are
concentrated in the  sediments through  mechanisms
such   as sedimentation, adsorption,  and  organic
complexation.

Chemical and physical sampling involve the collection
of  representative   samples   of  sediments,  with
methodologies dictated by the physical character of the
system (e.g., depth, substrate type) and  the  type of
analysis being conducted. In most cases, shallow-water
sediments can simply  be collected by hand  using a
stainless steel spoon,  spade,  or push-corer.  Deeper
systems, such as lakes and estuaries, may require the
use of vessel-deployed grab samplers or corers. These
types of  samplers are  described in existing guidance
(U.S.  EPA,  1990b)  and Standard Methods  (APHA,
1992). The grab or core is then subsampled in a manner
consistent with the requirements of individual analyses.

In most cases, the sample is placed in a plastic bag or
other container and transported to the laboratory in iced
coolers. While this approach is  appropriate for physical
analysis  and certain chemical  analyses (e.g., carbon
and metals), some analyses require special containers
or preservatives.  Parameter-specific requirements, as
well as the required volume  of  sample  for  various
analyses, are  listed  in  methodological   references
(Plumb, 1981).

Biological Sampling

Biological sampling of benthic  organisms depends on
the water body and the type of organism being sampled.
Estuaries, lakes, and large rivers typically are sampled
by a grab sampler of specified area and penetration
depth. Samples then are screened through a sieve, and
the organisms retained on the sieve are transferred to
a sample bottle and preserved. Streams  and small
rivers can be sampled using a variety of samplers, again
depending  on   depth,  flow  rate,   substrate,  and
community type. In addition, artificial substrates can be
employed which  minimize  the problem  of  locating
similar substrates in all sampling areas. Comprehensive
guidance exists for collecting biological samples using
these devices (U.S. EPA, 1990b).

Flow Measurement

Flow measurement of streams, rivers, and runoff in and
from drainage systems is needed to calculate pollutant
loads and to design BMPs. Flow rate measurements
can  be  made  using a variety of  methods:   The
velocity-area method  (ISO, 1979; USGS, 1982; USDI,
1984) can be used to estimate flow  rates in streams,
rivers and other open channels. In  this method, the
channel's cross-sectional  area,  as  computed  from
channel width and depth measurements, is multiplied
by flow velocity readings. Flow measurements should
be taken with a portable velocity meter at  20  and 80
percent of the depth, or at 60 percent of the depth at
regular intervals across the channel (Chow, 1959).

Flow measurements can also be made by automatic
devices installed  in channels,  storm drains, or  CSO
structures (U.S. EPA, 1975). These devices utilize  a
variety of  sensor  types,  including  pressure/depth
sensors and acoustic measurements of stage height or
Doppler effects  from flow velocity. Data are  stored in a
computer chip that can be accessed and downloaded
by portable computer. Data are processed based on the
appropriate pipe,  flume, or weir hydraulic  equations.
Field calibration of data using such equations is critical
because  these  types of data might  be influenced by
surcharging, backwater, tjdal flows, and other complex
hydraulic conditions typical of urban runoff flows.  Such
devices can be purchased, leased, or furnished as  a
contract service.

Accurate flow measurements can also be made at
hydraulic control structures, such as weirs or  flumes,
where  the  rate of flow is a  function of  the water
elevation. If project finances allow, portable weirs or
flumes can be  purchased  or leased and installed in
storm  drains,  sewers, or  channels  for taking flow
measurements during storms (USDI, 1984). Flow and
elevation can also be taken at concrete weirs  or staff
gages owned by the U.S. Geological Survey. For weirs,
flumes, and other standard structures, records of stage
height taken at the time of flow measurements can be
used to develop a stage discharge rating that  can be
used as a quick reference for future  readings (USGS,
1982).  Figure  5-1 provides  an example  of a stage
discharge rating curve for a  river.  In general, flow
measurement stations should  have uniform  channel
                                                  62

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           lo-

        a  e —
            5 —
            4 —
            3—
                                                      I              \
                                                      8            10

                                            River Discharge, cfs x 1,000
                          12
                                        14
Figure 5-1.  Example stage discharge rating curve.
conditions for six channel widths upstream to eliminate
any turbulence, to avoid tidal or backwater effects that
would interfere with flow patterns, and to allow adequate
mixing of upstream  flow from tributaries (U.S.  EPA,
1991a).

Rainfall Monitoring

Rainfall data are necessary to estimate the amount of
runoff generated during an event, which is then used to
predict runoff volumes and predict responses to events
of different magnitudes. Existing long-term rainfall data
might be available near the area from the network of
gages  operated  by  the  National  Oceanic   and
Atmospheric Administration. Because of the variability
in the possible distribution  of  rainfall  over a relatively
small area, a network of rain gages might be necessary
to support these objectives.  The  number  of gages
required depends on the size of the program, the area,
topography, season,  and typical characteristics of local
rainfall  events.  Available   resources   for  rainfall
monitoring should be concentrated  in critical  areas
under investigation. Guidance  in determining rain-gage
network density is available (U.S.  EPA, 1976).

Rainfall gages consist of  two types: nonrecording
gages, which  measure total rainfall,  and continuous-
recording  gages, which  measure  intensity over  the
duration of the event. The latter type is more desirable
for most urban runoff programs because an understanding
of the time-varying watershed hydrologic response to
rainfall variations within a storm event can be gained
from such data. One type of continuous-recording gage
is the tipping-bucket gage, which records the number of
times a calibrated bucket is filled  and subsequently
tipped  and  emptied  into  a larger reservoir.  Other
continuous gages utilize a weighing  mechanism to
record rainfall amounts.
Rainfall gages should be located in open spaces away
from  the  immediate  shielding effects  of  trees or
buildings.   Ground   installations  are   preferable (if
vandalism is not a significant problem). Roof installations
are another option, and public buildings, such as police,
fire, or public works buildings, are often used. The
installation should be in an unobstructed area of the
ground or roof.

Cost Estimating  for Data Collection
Programs

State and federal funding for urban  runoff control
programs  typically is limited; the burden of financing
these efforts therefore falls on a municipality. As the
data collection program is being developed, the cost of
the program should  be considered. A cost  estimate
should be prepared  for the entire program, including
in-house and  outside  services from consultants and
analytical   laboratories.  If  funding levels   are  not
adequate  to  complete  the  sampling  program,  the
                                                   63

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program should be redefined by scaling down the scope
of sampling (i.e., number of sampling stations and/or
sampling  frequency) or by using a phased approach
and completing critical  components  first and other
components as funding becomes available.

Data collection for an entire municipal area with multiple
watersheds can be very costly, and might use up limited
resources  that   could   be   applied   to   actual
implementation  of  controls.  Sampling  limited  but
representative areas and extrapolating this information
to  other  unmonitored  areas might  be  more  cost
effective.  Although such extrapolation  is  risky and
should be done with caution, it  might be necessary
given program budget constraints. As discussed earlier
in this chapter,  a focus  on  ecosystem  components
which integrate long-term effects (e.g., aquatic biota,
habitats, sediments) could yield valuable data at a more
reasonable cost.
Some  large  municipalities might have  the  in-house
resources to  undertake a comprehensive urban runoff
sampling   program,   including  staffing,   equipment,
analytical  capabilities,  and the  technical expertise
required    for  data  interpretation.   For   smaller
municipalities, or  those without  extensive technical
resources, the sampling program should take  full
advantage of technical assistance offered by state and
federal agencies; contracted laboratories can be used
for necessary analytical services.
The major cost elements of the data collection program
include the following:

• Personnel costs, in-house and/or contracted, for the
  field effort.

• Laboratory analysis costs.
• Monitoring  equipment costs.
• Miscellaneous equipment costs.
* Data analysis and  reporting costs.

Each item should  be estimated in as much detail as
possible. Labor costs should include direct salaries plus
overhead   and  profit costs  for contracted  work.
Laboratory analysis costs are often provided on a unit
cost-per-sample  basis.  Other equipment costs  are
based on  rental or purchase prices. Data analysis and
reporting will  include technical  labor plus clerical time,
and  perhaps office supplies and computer costs.

Data collection cost estimates  are highly site and
circumstance specific and range from several thousand
to millions of  dollars. As stated earlier, it tends to be a
major component, often the largest single element, of
the planning program. Therefore, designing the program
to respond to appropriate objectives requires the utmost
care.
Data Management and Analysis

Since data collection programs generate large amounts
of information, management and analysis of the data
are critical to a successful program. Even small-scale
programs, such as those  involving only a few storm
water and receiving-water monitoring stations,  can
generate hundreds of pages and thousands of data
records.  Monitoring  these stations over  time  adds
significantly  to the  amount  of  data. Thus, a  key
requirement is the ability  to  store large  amounts  of
environmental data in an accessible format, allowing the
data to be manipulated for a variety of  analyses.

Methods to manage and analyze data are presented in
this  section:  spreadsheets, graphical  presentations,
database   management  systems,   and   statistical
analysis. Examples of how these methods can be used
to assess a sample data set are given.  These methods
can also be used to analyze existing data (Chapter 4).
More detailed  methods  of  assessment,  such  as
watershed and receiving water modeling, are presented
in Chapter 6.

Spreadsheets
Selection  of  the  most efficient  method  for  data
management  depends on the scale of the program. For
small-scale   urban  runoff  programs, a  computer
spreadsheet program can be used. Entry of data into a
computer format permits easy manipulations, such as
calculations  and  graphics. Whether  a computer  is
available or not, data records should be organized into
tables by sampling station. An example of such a table
is shown in Table  5-5. Parameters recorded during a
survey can be entered into columns of  data, with each
row  in the table representing a  sampling  event. For
storm event  monitoring,  each  row can  consist  of
consecutive samples collected during  the event. The
sample  ID number, which  should be unique to every
sample, can be used as the principal sample identifier
should data be exported to a GIS or  other computer
applications.
Most spreadsheet programs can also be used to create
graphs of the  data and to perform calculations. Once a
format has been developed for data entry, calculations
such as contaminant load or percent oxygen saturation
can be automatically performed as the data are entered.
An example of a format used to calculate nitrogen loads
(ammonia and total nitrogen) is presented in Table 5-6.
Spreadsheet  files  can be  combined  as  required  to
present selected information, perform investigations,  or
export data to other computer applications such as GIS
(see Chapter 4) or urban  runoff and  receiving water
models (see Chapter  6).
                                               \
                                                  64

-------
Table 5-5. Example Spreadsheet Format
Sample
6
10
23
38
42
47
51
61
65
69
75

Month
7
7
7
9
9
9
9
10
10
10
10
Date
Day
18
19
20
4
5
5
6
17
18
18
18

Hour
2030
0920
1020
1710
0656
1750
0003
1730
0525
1117
1714
River
Stage,
ft
2.31
2.34
2.15
2.61
2.59
2.55
2.63
2.48
2.72s
2.75
2.57
for Water Resource Data
Temp.,
°C
24.8
21.2
22.5
23.0
21.8
23.0
22.7
18.5
18.5
18.7
18.5
PH
7.7
7.7
7.8
8.3
7.8
8.3
7.6
7.6
7.6
7.1
7.3
DO,
rng/L
7.65
8.14
8.35
8.80
8.20
8.78
7.75
8.90
8.50
8.90
8.20
Conduc-
tivity,
mS/cm
0.23
0.23
0.22
0.20
0.20
0.20
0.19
0.19
0.19
0.19
0.19
Fecal
Coliforms,
MPN/100 mL
<20
20
<20
<20
<20
20
80
560
300
140
140
TSS,
mg/L
<1
1.2
<1
1.8
2.9
2.8
3.1
4.5
6.8
5.9
5.8
BODS,
mg/L
5.6
4.4
<4
<2
<2
<2
<2
<2
<2
3.2
<2
Total
Nitrogen,
mg/L
0.899
0.897
0.853
1.081
*
0.775
0.832
0.914
0.905
0.903
*
Total Phos-
phorus,
mg/L
0.061
0.033
0.030
0.142
0.113
0.122
0.153
0.059
0.049
0.065
0.048
* Sample not analyzed.
Table 5-6.  Spreadsheet to Calculate Nitrogen Loads
Sample
6
10
23
38
42
47
51
61
65
69
75

Month
7
7
7
9
9
9
9
10
10
10
10
Date
Day
18
19
20
4
5
5
6
17
18
18
18

Hour
2030
0920
1020
1710
0656
1750
0003
1730
0525
1117
1714
Freshwater
flows, tf/s
19.4
20.5
12.1
35.9
35.3
33.1
37.1
28.0
45.3
49.2
33.9
Total Nitrogen,
mg/L
0.899
0.897
0.853
1.081
*
0.775
0.832
0.914
0.905
0.903
ft
TN Load,
kg/d
42.6
44.9
25.3
94.9
•ft
62.7
75.4
62.5
100.4
108.6
*
Ammonium,
mg/L
0.015
0.013
0.011
0.017
0.021
0.004
0.010
0.093
0.098
0.204
0.180
Ammonia
(NH4)
Load, kg/d
0.7
0.7
0.3
1.5
1.8
0.3
0.9
6.4
10.9
24.6
14.9
* Sample not analyzed.

Graphical Presentation

Graphic   displays   enhance   data   analysis  and
interpretation.  Plots translate large sets  of data into
easy summaries. Another effective use of graphics is
the spatial presentation of environmental data, such as
on a hand-drawn or GIS-simulated map (see Chapter
4).  Whether using  the  capabilities of  spreadsheet
programs or a GIS, or plotting data on graph paper by
hand,  a  trend analysis  for  a particular parameter,
location, or sampling program can be developed from a
data set. Figure 5-2 illustrates a simple line plot of
routine monitoring data for fecal coliform data taken
monthly over a 1-year period. Figure 5-3 depicts fecal
coliform data at a receiving water station influenced by
a storm sewer during a 24-hour period after a rainfall
event. In both figures, the state water quality criterion
for fecal coliform bacteria is indicated and quick, visual
comparisons of the collected data to the criterion can
be made.

Database Management Systems

A computer-based database management system is
used to store collected data and to permit easy retrieval
for subsequent calculations and analyses. Database
design  involves   a   knowledge   of the  database
management system being used and the requirements
of database manipulation and interaction with other
software. The data base can be coordinated with, or be
part of, a GIS. In addition, the data base can be used
                                                  65

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                       500
                            Jan. Feb. Mar. Apr.  May June July Aug. Sept.  Oct. Nov. Deo.
                                                    Sampling Month
 Figure 5-2.  Fecal coliform densities at Station A.
                       500
                            300
                                    600
                                           900
                                                    1200    1500

                                                    Sampling Time
                                                                  1800
                                                                          2100
                                                                                  2400
Figure 5-3.  Fecal coliform densities at Station E.

as input to urban runoff and receiving water models (see
Chapter 6).

Types of sampling information that could be included in
the data base include: sample identification number,
type of sample (e.g., rain water), sampling  date and
location,  analyses  performed,  results  of  chemical
analyses, detection limits, name of laboratory, name(s)
of personnel collecting samples, dimatic information, and
comments regarding the sampling or analyses. Database
queries can request information that focuses on specific
attributes. For example, the user may select all dissolved
oxygen concentration data for a specific sampling location,
or the user may select all dissolved oxygen data below
a certain  concentration from all stations to determine
compliance with water quality standards. More detailed
information concerning  data bases is available  in the
user manuals of database management software and in
the literature (Date, 1985; Korth and Silberschatz, 1986;
Maier,  1983; Hursch et al., 1988).
                                                    66

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Statistical Analysis
Statistical analyses  can be conducted to establish
trends and comparisons of the collected data such as
pollutant concentrations and loadings associated with
specific sampling locations or storm events. Statistical
interpretation provides information that can  be used to
determine  characteristics of the  data  set such as
whether a concentration is high or low compared to the
others, the amount of variation among the data, and the
way  in  which the  data are  distributed.  Statistical
methods can  also be applied to results of biological
sampling  of receiving waters  and sediments. These
methods  can  be  used to  identify shifts  in species
abundance and community structure which might result
from exposure to pollutants.
Commonly used statistical calculations  are shown in
Table 5-7 and discussed in the following sections. Table
5-8 presents  results  for TSS samples from a  CSO
monitoring program  to  illustrate  the  use of these
statistical calculations. This CSO monitoring program
included 10 sampling sites at combined sewer overflow
locations for two storm  events (November 3 and 22).
Table 5-8  also  includes estimates for  flow-weighted
composites for comparison with the statistical values.
Flow-weighted composite data are frequently generated
when discrete sampling is performed within a storm
event, as discussed earlier in this chapter. Figure 5-4
depicts the results  from one  sampling  site plotted
against  the   overflow  discharge  rate and  rainfall
hyetograph to illustrate  the relationship between flow
and discrete samples upon which the  flow-weighted
composite value is based.

Measures of Location
Statistical measures of location describe the relationship
between various values in  a  data set, including the
mean,  median,  and  frequency  distribution. These
statistical values can be  used to determine average
values and the most likely value of future sampling
results.
Mean. The arithmetic mean, or average, is calculated
by  summing the observations  and then dividing the

Table 5-7.  Commonly Used Statistical Calculations
                                sum by the number of observations (see Table 5-7). A
                                mean  value  can  be  used  as  a  benchmark  for
                                comparison  to individual data points  or to regulatory
                                standards.  In  some   cases,   state  water  quality
                                standards employ the use of the geometric mean (e.g.,
                                bacterial  standards).  In this  case,  the  individual
                                observations are multiplied,  and  the nth root  (n =
                                number  of  observations)  is calculated.  Arithmetic
                                means for each station  and  an  overall mean for  the
                                entire storm are provided in Table 5-8.

                                Median. To obtain the median or central point value of
                                a  data  set, the observations must first  be put into
                                numerical order and then divided into  two  equal parts.
                                If the number of observations is odd, the median is the
                                single middle value. If the number is even, the median
                                is  obtained by calculating the mean of the two middle
                                values of the  ordered  list.  Median  values for  each
                                station and an overall median for the  entire  storm  are
                                provided in Table 5-8.

                                Frequency Distribution. Frequency  distributions  are
                                developed by  dividing  the  range of  data  points  or
                                observations into evenly spaced  intervals  and then
                                counting the  number of observations that fall within
                                each interval. A relative frequency distribution  is
                                obtained  by dividing each number in the  frequency
                                column by the number of observations in the data set
                                (Devore,  1987). A  graphical  representation  of a
                                frequency distribution can  be obtained by  plotting a
                                histogram, or bar chart, of the intervals along the x-axis
                                and the number of observations along the y-axis.

                                Many types of environmental data are either normally
                                or lognormally distributed/Normally distributed data are
                                symmetric about the mean (which in the case of normal
                                distribution  is equivalent  to the  median),  with a
                                histogram that resembles the shape  of a bell curve.
                                Lognormally distributed data could exhibit a curve which
                                is  skewed to the right or left, or could be flatter or more
                                peaked than a normal curve. Storm water and CSO data
                                are often  lognormally distributed.
                                Many   statistical  tests  (parametric  statistics)   to
                                determine if mean  values from  two sets  of data  are
                                significantly different require  that data  be  normally
Statistical Parameter
Arithmetic mean
Geometric mean
Variance
Formula
x = (x
X = "N
•i + x2 +...+ XnJ/n
'(X,i X X2 X . . . X X n)
Variable Definitions
Xn = value of the n* data point
n = number of observations in a data set
X|, Xi = variables that are being correlated
Correlation coefficient
s2 = pxl2-(£x,)2/n]/(n-1)

r = PCX, - x)(y, -

 = [nS(X|)(y,) -
                                                   67

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Table 5-8.  CSO Sampling Results for Total Suspended Solids
Sit*
003
Mean value
Median value
Flow-walflhtad
value
009




Mean value
Median value
Row-walghted
value
C1IC
WIK1"

Moan value
Median value
Flow-weighted
value
023

Moan value
Median value
Flow-weighted
value
080





Mean value
Median value
Flow-weighted
value

Date
11/3
11/3
11/3
11/3
11/3
11/3
11/3

11/3
11/3
11/3





11/3
11/3
11/3
11/3
11/3
11/3
11/3
11/3

11/3
11/3
11/3
11/3
11/3
11/3
11/3
11/3
11/3




11/3










Time
0525
0545
0615
0632
0632
0715
0815

0705
0805
0905





0745
0815
0845
0945
1045
1215
1215
1345

1100
1115
1145
1215
1245
1315
1415
1515
1515















TSS,
mg/L
35
31
38
48
46
31
42
37
38.5
37

160
110
63



111
110
109

400
120
73
58
29
20
18
25
103
58
105

150
91
110
55
44
46
14
26
28
67
50.5
58

No
data










Date
11/22
11/22
11/22
11/23
11/23
11/23


11/23
11/23
11/23
11/23
11/23
11/23
11/23

11/23
11/23
11/23
11/23
11/23
11/23
11/23
11/23

11/22
11/22
11/22
11/22
11/22
11/22
11/23
11/23
11/23




11/22
11/22
11/22
11/23
11/23
11/23
11/23
11/23





Time
1530
1545
2150
0215
0315
0535


0000
0015
0015
0210
0310
0410
0810

0115
0130
0300
0300
0400
0510
0510
0800

1820
1920
2020
2120
2120
2220
0020
0220
0520




1605
1620
1650
0105
0205
0405
0605
0905





TSS,
mg/L
27
33
48
16
49
22
32.5
30
27

100
110
160
49
44
77
66
78.5
71.5
59

80
140
180
190
76
30
24
31 '
90
78
45

38
71
33
11
12
15
13
58
160
50
52
83

110
140
49
45
74
21
30
33
63
47
42


Site
012
Mean value
Median value
Flow-weighted
value
003



Mean value
Median value
Flow-weighted
value
070
Mean value
Median value
Flow-weighted
• value

086
Mean value
Median value
Flow-weighted
Vdl(J6

088





Mean value
Median value
Flow-weighted
value

All Sites
Combined
Mean value
Median value
Date
11/3
11/3
11/3
11/3
11/3



11/3
11/3
11/3
11/3
11/3
11/3
11/3


11/3
11/3
11/3


11/3
11/3
11/3


11/3
11/3
11/3
11/3
11/3
11/3










Time
0650
0705
0735
0835
0935



0725
0740
0810
0910
0910
1010
1210


1025
1255
1325


0840
0855
0925


0840
0940
1040
1140
1240
1240










TSS,
mg/L
110
63
51
35
95
71
63
59

160
39
17
47
130
230
160
116
124.5
160

42
13
18
24
18 .
27

27
21
17
22
21
23

160
91
42
25
28
24








73
45
Date
11/23
11/23
11/23
11/23
11/23
11/23
11/23
11/23


11/23
11/23
11/23
11/23




11/23
11/23
11/23
11/23
11/23
11/23


11/22
11/23
11/23
11/23
11/23
11/23


11/23
11/23
11/23
11/23
11/23
11/23
11/23
11/23








Time
0130
0145
0215
0315
0415
0615
0615
0805


0015
0030
0200
0300




0300
0330
0430
0530
0720
0920


1605
0025
0225
0335
0540


0205
0220
0250
0350
0450
0550
0550
0750








TSS,
mg/L
68
200
170
170
60
21
22
23
102
68
82

44
32
22
190




360
110
120
73
40
31
122
91.5
58

150
140
340
230
170
67
183
160
266

780
240
150
310
230
51
47
41
257
230
161



104
66
                                                       68

-------
                 1.2

                 1.1

                  1

                 0.9

                 0.8
              •a
              E.  0.7

              £  0.6

                 0.5

                 0.4

                 0.3

                 0.2

                 0.1

                  0
LJLUU LLU
                 I
                                               SITE 012
                                            Novembers, 1992
Illlllilllllilllllllllllllllllllll
             Row
                                         —0.01 i
                                         —0.02",
                                                           -120

                                                           -100

                                                           - 801
                                                                !
                                                           - 60t

                                                           - 40 '

                                                           - 20
                      5:00
          6:00        7:00        8:00
                    Time of Day, a.m.
                                                                   9:00
                                                                             10:00
Figure 5-4.  Relationship between flow and pollutant concentrations.
distributed.  It is therefore  necessary  to  determine
whether a particular data set satisfies this assumption
prior  to  employing  parametric statistics.  Tests  for
normality (e.g., Kolmogorov-Smirnov one-sample test,
Sokal and Rohlf, 1969) are used to compare the data
distribution with a normal one to  determine if it is
sufficiently similar.

Prior to comparisons with other data sets, such a test
was performed on the pooled data for all measurements
of TSS given  in Table 5-8. A histogram of the pooled
(untransformed)  data was  made first (Figure 5-5), A
Kolmogorov-Smirnov one-sample  test  indicated  the
data  were   significantly  different  from  a  normal
distribution (dotted line in histogram). A log transform
was then applied (Figure 5-6), and the test for normality
repeated. The transformed data  were  found  to  be
normally distributed. The transformed data now met the
assumptions for parametric statistical analysis.  In  the
event that all attempts at data transformations prove to
be  ineffective, nonparametric statistics  (e.g., Mann-
Whitney U-test)  can still  be employed for comparison
and assessment of data.

Many parametric and nonparametric tests can be found
in statistical packages for personal computers/These
statistical packages can easily access information from
data bases, and greatly facilitate the evaluation of  the
data generated by a monitoring program.

Measures of Variability

Statistical measures of variability describe how closely
the data  set is grouped around  the  mean  value.
                              Statistical tests performed to determine significance
                              between two means require as a basic assumption that
                              the variance components of the two data sets are not
                              significantly different.  The  two  most  frequently  used
                              measures  of  variability are  variance and standard
                              deviation.
                              Variance.  Variance   is  a  measurement  of  the
                              dispersion  of observations  about the  mean—the sum
                              of  the  squares  of the  differences  between  each
                              observation and the mean divided by the degrees of
                              freedom in the data set (see  Table  5-7).  The term,
                              degrees of freedom, equals the number of observations
                              minus 1.

                              Standard  Deviation.  The standard deviation is the
                              square  root of the  variance and  is expressed in the
                              same units as the mean. For a  normal distribution, the
                              data included in the range of 1 standard deviation from
                              the mean represent 68.26 percent of the total data set.
                              A range of  2 standard  deviations from  the  mean
                              represents 95.44 percent of the data set and a range of
                              3 standard deviations from the mean represents 99.74
                              percent of the data set.  For example, the standard
                              deviation in the pooled TSS data for all sites was 102
                              mg/L,  indicating  a high degree of variability when
                              compared with an overall mean value of 91 mg/L.

                              Confidence Intervals

                              To   determine  whether  an   estimated  parameter
                              measurement such as a  contaminant  concentration
                              measured  in  a laboratory  or forecasted by  a model
                              represents the actual value of that parameter, the
                                                   69

-------
n
                                                    n
                                                                                                        r-30
                                                                                                         -24
                                                                                                         -18
                                                                                                         -12
                                                                                                         -6
n
                                                   mg/L
Figure 5-5. Untransformad total suspended solids (TSS) data.
                                                                                                        r-10
                                                                                                         -8
                                                                                                              I
                                                                                                         -6
                                                                                                         -4
                                                                                                         -2
                                                                                                       -L.O
                                                   log mg/L
Ftgura 5-6.   Log-transformed total suspended solids (TSS) data.
                                                        70

-------
estimated value can be  compared to a confidence
interval. A confidence interval can be interpreted as the
probability  that  an estimated value  falls  within  the
calculated  limits  of  the interval. For  example, a
95-percent confidence interval indicates  a 95-percent
probability  that  the  estimated  value  falls  within  the
specified limits of that confidence interval. Thus, only 5
percent of the estimated values would fall outside of this
range. The technical  details  of deriving confidence
intervals are  beyond  the scope  of  this  document;
however, there are numerous references that could be
useful, including Devore (1987) and other textbooks on
probability and statistics.

Correlation Coefficient. The correlation  coefficient (r)
provides useful information concerning the relationship
between pairs of data, denoted as x and y. An example
would be the relationship between  TSS concentrations
from a site and  the area that contributes runoff to the
site. The value of  r does not depend  on which of the
two variables  is labeled  "x" and which is labeled 'V,"
nor does it depend on the units  of x and y. Generally,
a  correlation   coefficient  is   considered   weak  if
0 < Irl < 0.5, strong  if 0.8 < Irl < 1.0,  and  moderate
otherwise (Devore, 1987).

Analysis of Biological Data
The evaluation of biological data could involve  a
number of statistical approaches,  which include both
qualitative and quantitative methods. Qualitative methods
frequently include the use of indicator organisms whose
presence or absence indicates the level of water quality.
Quantitative methods include comparisons of biomass,
organism densities, and community indices.
Qualitative Methods, Indicator species have been
used for several community levels, including  plankton,
fish,  and benthic  macroinvertebrates.  For  example,
phytoplankton  species  have  been  categorized  as
indicative of clean  and polluted water, and responsible
for taste and odor problems  in   reservoirs (APHA,
1992). Indicator species of  organic  enrichment  and
other  pollutants  in   marine  systems  have  been
described by  Pearson and Rosenberg (1978). In the
case of freshwater  benthic macroinvertebrates  and
fish,  pollution-tolerant  or -intolerant  organisms have
been assigned  index values corresponding to  their
pollution tolerance (Hilsenhoff, 1977,  1987; U.S. EPA,
1989; summarized in U.S. EPA, 1990b). These index
values typically  utilize  scales of 0 to  5, or 0 to 10, to
indicate the level of tolerance to pollutants.
The use of benthic macroinvertebrate  indicator species
is illustrated in results from a stream survey to assess
the relative impact of nutrients and other contaminants
from an area affected by  sewage leachate (Figure 5-7).
In the survey, EPT taxa (Ephemeroptera, Plecoptera,
Trichoptera = mayflies, stoneflies, and  caddisflies) were
used to represent species sensitive to pollution, while
chironomid dipterans (blackflies), nonchironomid flies,
and  oligochaete  worms  were  used  to  represent
pollution-tolerant organisms.

The results reflected a fairly even distribution of the four
groups of organisms at the upstream control site (Site
A). Pollution-tolerant species, particularly the oligochaete
worms which are good indicators of organic enrichment,
were found in  elevated  numbers downstream of the
impact area (Site  B). Further downstream (sites C
through E), the  relative abundance of the four groups of
organisms came  to reflect  conditions found  at  the
upstream control site. In many urban environments, it
might be difficult to find an upstream control site. This
is common  for  feeder  streams and  creeks which
originate within the urban area  such that the entire
reach is impacted. In such cases, it is  necessary to
consider reference sites  in other areas which are not
affected.                          .

Quantitative   Methods.  Quantitative  methods  to
analyze  biological data  utilize  results  for biomass,
number  of  organisms,   and  species  composition.
Statistical methods  described  in earlier sections are
used  to  interpret  numeric  data  on  biomass  and
densities. Community composition is analyzed through
the  use  of diversity and similarity indices, which
examine  the  number  of  organisms  and taxa  to
determine if communities are stressed by pollutants. A
number of these indices exist,  which are described in
the literature (Washington, 1984).

The  most  frequently used diversity  indices describe
species diversity, dominance, and evenness (Table 5-9),
which provide the basis for comparisons of results from
different sampling stations and study areas. Because of
the influence of natural variability on the  distribution of
species, such  comparisons  are restricted to similar
habitats  such  as fast-moving  sections  of  a  shallow
stream (riffles), or deeper pooled areas. These indices
have been employed in ecological studies for a number
of years, permitting comparisons with historical data bases.

Calculation of these indices  using  the data in the
stream survey  (Table 5-10) mirrored the results for the

Table 5-9.  Commonly Used  Ecological Diversity Indices
Shannon-Wiener Diversity Index

Simpson's Dominance


Evenness
H'=£{ni/n[ln(ni/n)]}
   where i = 1 . . . s
 = H7ln(s)
where:
n, = number of individuals in a species i of a sample from a
     population
n = number of individuals in a sample from a population
s = number of species in a sample or population (also called
     richness)
                                                    71

-------
Table 5-10.  Diversity Indices for Sewage Leachate-Affected Stream Samples
Station
A
B
C
D
E
Total Taxa
44
33
31
39
15
Mean Number of
Organisms per ft2
372.2
1261.9
1193.1
796
60
Diversity
2.932
1.196
1.864
1.541
2.273
Dominance
0.077
0.536
0.263
0.442
0.138
Evenness
0.77
0.34
0.54
0.42
0.84
distribution of indicator organisms illustrated in Figure
5-7. Diversity and evenness values were both highest
at the control Site A, and lowest at Site B, indicating the
shift  toward  opportunistic,  pollution-tolerant species
which had a competitive advantage over less tolerant
species. These results can also be plotted in a manner
similar to the indicator species results. Statistical tests
to  determine  the  significance  of  the   observed
differences can  be  easily  performed  following the
methods of Solow (1993).
Similarity indices permit comparisons of results to a
reference station by calculation of similarity coefficients.
These similarity coefficients can be subjected to cluster
analysis, with the results illustrated through  the use of
dendrograms which graphically group similar communities
together. Guidance exists using examples of the most
widely  used  indices  (U.S.  EPA,  1990b), including
examples  of  applying statistical methods  described
earlier to determine the level of significance associated
with comparisons using these quantitative approaches.
A dendrogram for the Bray-Curtis coefficient calculated
from the stream survey example (Figure 5-8) illustrates
the similarities between sites influenced by the sewage
leachate (Sites B through D). The upstream control site,
A, and the most downstream site, E, clustered together,
indicating a high degree of dissimilarity with the sites
most influenced by the sewage leachate. Again, tests of
significance can be  applied to  the results, and  are
typically included in  statistical  packages  which  are
available to run cluster analyses.
               100
                                                                          Legend
                                                                            EPTTaxa
                                                                          A Nonchironomid Diptera
                                                                          • Chironomid Diptera
                                                                          o Oligochaetes
                                                  Station
                                         -Sewage leachate

Figure 5-7.  Distribution of macrolnvertebrate Indicator species along a sewage leachate-affected stream.
                                                     72

-------
     o —i
I
   0.1
    0.2 —
   0.3 —
   0.4 —
   0.5 —
   0.6 —
   0.7 —
    0.8 —
    0.9 •
    1.0 •
                        Bray-Curtis Index
Figure 5-8.  Cluster analysis dendrogram for sewage-affected
          stream survey results.
References
When an  NTIS number is cited in a reference, that
document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650

APHA. 1992.  American  Public  Health  Association.
  Standard methods for  the analysis of water and
  wastewater, 18th edition. Washington,  DC.
Chow, V.T. 1959. Open-channel hydraulics. New York,
  NY: McGraw-Hill.

Date, C.J. 1985. An introduction to database systems.
  Menlo Park, CA: Addison Wesley.
Devore,  J.L.  1987.  Probability  and  statistics  for
  engineering  and  the  sciences,  second  edition.
  Monterey, CA: Brooks/Cole Publishing Company.

Hilsenhoff,  W.L.   1977.  The  use  of  arthropods  to
  evaluate water quality of streams. Dept. of Natural
  Resources, Madison, Wl. Tech. Bull. No. 100.

Hilsenhoff, W.L.  1987. An improved biotic index  of
  organic stream  pollution. Great  Lakes  Entomol.
  20:31-39.

Hursch,  C.J.,  and J.L.  Hursch.  1988.  SQL, the
  structured query language. Blue Ridge Summit, PA:
  TAB BOOKS, Inc.

ISO.    1979.     International    Organization    for
  Standardization. Measurement of liquid flow in open
  channels.  Case  Postale  56-CH  1211*  Geneva,
  Switzerland.  ISO Standard 748-1979E.
Korth,  H.F., and  A.  Silberschatz.  1986. Database
  system concepts.  New York, NY: McGraw-Hill.

Maier,  D. 1983. The theory of relational databases.
  Computer Science Press.
Pearson, T.H.,  and R. Rosenberg. 1978. Macrobenthic
  succession  in  relation to organic enrichment and
  pollution of the  marine environment. Oceanor. Mar.
  Biol. Ann. Rev. 16:229-311.
Plumb,  R.H., Jr.  1981.  Procedures for handling and
  chemical analysis of sediment and water samples.
  Technical Report  ERA/CE-81-1. U.S. Environmental
  Protection Agency/U.S.  Army Corps of Engineers
  Technical Committee on Criteria for Dredged and Fill
  Material. Vicksburg, MS: U.S. Army Waterways Exp.
  Station.

Sokal,   R.R.,  and  F.J.  Rohlf.  1969.  Biometry—the
  principles  and  practice of statistics  in biological
  research. San Francisco, CA: W.H. Freeman and Co.
  776 pp.
Solow,  A.R.   1993. A  simple  test  for change  in
  community structure. J. Animal Ecology 62:191-193.

USDI.  1984. U.S.  Department of the Interior. Water
  measurement manual.  Bureau of Reclamation Water
  Resources Technical Publication. Washington, DC:
  U.S. Govt. Printing Office.

U.S. EPA. 1975. U.S. Environmental Protection Agency.
  Sewer  flow   measurement;   a   state-of-the-art
  assessment. EPA/600/2-75/027 (NTIS  PB-250371).
  Washington, DC.

U.S. EPA. 1976. U.S. Environmental Protection Agency.
  Methodology for the  study of urban storm generated
  pollution  and   control.  EPA/600/2-76/145  (NTIS
  PB-258743). U.S. EPA Office  of Research  and
  Development.
                                                 73

-------
U.S. EPA. 1982. U.S. Environmental Protection Agency.
  Handbook for sampling and sample preservation of
  water  and  wastewater.  EPA/600/4-82/029  (NTIS
  PB83-124503). Cincinnati, OH:  U.S. EPA Office of
  Research    and    Development,    Environmental
  Monitoring and Support Laboratory.
U.S.  EPA.  1983a.  U.S.   Environmental  Protection
  Agency. Interim  guidelines and specifications for
  preparing    quality   assurance  project    plans.
  EPA/600/4-83/004 (NTIS  PB83-170514). U.S. EPA
  Office of Research and Development.
U.S.  EPA.  1983b.    U.S.  Environmental  Protection
  Agency. Guidelines for the monitoring of urban runoff
  quality. EPA/600/2-83/124 (NTIS PB84-122902). U.S.
  EPA Office of Research and Development.
U.S. EPA. 1984. U.S. Environmental Protection Agency.
  Guidelines for preparation of combined  work/quality
  assurance project plans for environmental monitoring.
  Office of Water Regulations and Standards, QA-1, May
  1984. Washington, DC.
U.S. EPA. 1986. U.S. Environmental Protection Agency.
  Quality criteria for water, 1986. EPA/440/5-86/001.
  Washington,  DC:  U.S.  EPA  Office  of  Water,
  Regulations and Standards.
U.S. EPA. 1989. U.S. Environmental Protection Agency.
  Rapid bioassessment protocols  for use in  streams
  and rivers:  benthic macroinvertebrates and fish.
  EPA/440/4-89/001.
U.S. EPA. 1990a. U.S. Environmental Protection Agency.
  Hazardous and toxic wastes associated with urban
  runoff. In: Remedial action, treatment, and disposal
  of hazardous wastes: proceedings of the 16th Annual
  Hazardous Waste Research Symposium. EPA/600/
  9-90/037 (NTIS PB91-148379). Washington, DC: U.S.
  EPA Office of Research and Development.

U.S. EPA. 1990b. U.S. Environmental Protection Agency.
  Macroinvertebrate field and laboratory methods for
  evaluating the biological integrity of surface  waters.
  EPA/600/4-90/030  (NTIS PB91-171363). U.S. EPA
  Office of Research and Development.

U.S.  EPA.  1991 a.  U.S.   Environmental  Protection
  Agency. Guidance manual for the preparation of part
  1 of the NPDES permit applications for discharges
  from  municipal  separate storm  sewer  systems.
  EPA/505/8-91/003A.  U.S.  EPA Office  of   Water
  (EN-336).

U.S. EPA. 1991 b. Technical support document for water
  quality-based  toxics  control.   EPA/505/2-90/001.
  Washington, DC: U.S. EPA Office of Water.

U.S. EPA. 1993. U.S. Environmental Protection Agency.
  Investigation of inappropriate pollutant entries into
  storm   drainage   systems,   a   user's    guide.
  EPA/600/R-92/238 (NTIS PB93-131472). Edison, NJ:
  U.S. EPA Office of  Research and Development.

USGS.  1982.  U.S. Geological Survey. Measurement
  and computation of streamflow: vol. 1—measurement
  of stage  and discharge; vol.  2—computation  of
  discharge. Water-Supply Paper  2175.

Washington, H.G. 1984. Diversity, biotic, and similarity
  indices: a review with special relevance to aquatic
  ecosystems. Water Res. 18(6)653-694.
                                                 74

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                                             Chapter 6
                                  Assess and Rank Problems
This chapter presents methods for evaluating available
or newly collected data in order to assess problems.
Problem assessments,  as defined in  this chapter, are
evaluations  performed  to determine the  extent and
severity  of  urban runoff-related  problems. Problem
assessments are used  to determine the need for and
appropriate  level of  pollution  prevention and control
measures for the program. It is important to consider
both existing  and  potential  problems, so that the
program addresses  resource  protection,  as well as
problems that already exist.

The first step is  defining problem assessment criteria,
which are used to assess the extent  or severity of an
urban runoff-related problem. Following this definition, the
most commonly used methods of problem assessment
are presented, including pollutant source assessments,
resource assessments, institutional assessments, and
goals and objectives assessments. Finally, methods for
ranking problems based on results of  the assessments
are included in this chapter because of the complexity
of urban runoff problems and the frequent need to set
priorities. Results of problem assessment and ranking
presented in this chapter provide the basis for  BMP
screening and selection  in subsequent steps of the
planning process.

Problem Assessment Criteria
Problem assessments  can address  a wide range of
issues, including:

• The types of urban runoff pollution in the watershed.
• The extent to which these pollution sources adversely
  affect resources.
• The institutional needs and constraints in addressing
  the problems.

• The goals established for the program area.

Criteria for  the  assessment  can be  developed  to
address these major issues, to determine the important
issues, and to provide a basis for problem assessment.
Only criteria  considered  most critical and helpful in
distinguishing between  problems should be selected.
Assessment criteria, such as those listed in Table 6-1,
can be evaluated qualitatively or quantitatively. These
criteria are briefly described below and elaborated upon
later in  the  chapter in the discussion of assessment
methods.

Pollutant Source Criteria

Assessment criteria focusing on pollutant characteristics
and the pollutant sources that  affect a resource are
among the most critical in determining which problems
should be addressed. Pollutant source criteria, such as
those listed in Table 6-1, describe the range of pollutant
characteristics and sources and the size of each source.
The  distance  between the source and the  affected
resource and the mode of pollutant transport are also
useful assessment criteria. Pollutant loading during wet
weather versus dry weather can also be considered.
Tools useful in evaluating  pollutant source  criteria
include GIS and urban runoff models (described later in
this chapter).

Resource Criteria
Resource criteria assess effects on  resources and aid
in determining locations where preventive and corrective
measures are needed. Water resources of various types
(e.g., ground water, surface water, and drinking water)
are often  the driving  force for such assessments, but
many other types of resources,  such as  biological,
wildlife,  and infrastructure could  be appropriate to
consider.  Examples of these assessment criteria, as
listed in Table 6-1, describe the importance or value of
a resource  with respect to issues such  as habitat,
recreational use, and public water supplies. The current
and desired uses of a resource may be included as
resource criteria. The .degree to which a resource is
impaired  and  the type of impairment may  also be
considered. Tools such as receiving-water models and
biotic indices (see the case study at the end of  this
chapter) and habitat evaluation procedures are used to
assess the existing conditions and simulate  responses
of the resources to potential preventive and corrective
measures. Information gathered during existing conditions
assessment (Chapter  4) and  data collection and
analysis  (Chapter 5)  are useful   in  analyzing  the
resource criteria. The  relative health of each resource
                                                  75

-------
 Table 6-1.  Criteria for the Assessment of Pollution Problems
 	(Adapted from U.S. EPA, 1987a)
 Pollutant Source

 "type of pollutant
 Pollutants typically associated with the source
 Source magnitude/pollutant loading
 Transport mechanisms to the resource (direct pipe, overland flow
 or ground water)
 Wat'/dry-woather trends

 Resource

 Existing use of the affected resource (type, status, and level of
 use)

 Designated or desired use of the affected resource
 Type and severity of Impairment

 Relative value of resource affected

 Institutional
 Available  resources and technologies
 Understanding of problems and opportunities
 Appraisal  of potential for solving the identified problem
 Implemontability of controls
 Applicable regulations
 Muitiagoncy responsibilities
 Funding sources and limitations
 Public perception

 Goals and Objectives
 Water resource goals (water use objectives)
 Technology-based goals
 Land use  objectives
 Objectives of planner and sponsor


 In a community and  the  desire of the community  to
 improve its quality helps determine  the  priorities for
 implementation.

 Institutional Criteria

 Urban runoff-related problems  can also be assessed
 using criteria that focus on the institutional constraints
 on regulators,  owners, and the  public.  Institutional
 criteria are based on applicable  regulations, preferences
 of the local authorities and regulatory agencies, funding
 sources  and  limitations,  multiagency responsibilities
 and overlaps,  and public  acceptance of the  program.
 Interviews  and  meetings  with   interested  parties,
 including agencies,  environmental  groups,  advisory
 groups, and private citizens, can be conducted to help
 develop  institutional criteria. Questionnaires can  be
 prepared and distributed to help  identify concerns.
Complaints, either filed with local authorities or available
through  interviews with citizens,  also provide useful
 input. Knowledge of problems gained through public
 interaction programs can help to ensure public support
 of  urban  runoff pollution  prevention  and  control
 programs which  are implemented later.  Examples of
 institutional criteria are listed in Table 6-1.

 Goals and Objectives Criteria

 Urban runoff problems can be evaluated with respect to
 current and future goals. Using goals and objectives
 assessment criteria,  presented in Table 6-1, allows the
 program  team to focus  on  problems where preventive
 or corrective  measures would provide  the  greatest
 benefit. One goal, for example, might be to increase the
 usage of public beaches by improving the conditions of
 degraded water bodies meant for swimming. Application
 of goals  and  objectives criteria could identify where
 corrective measures would provide the greatest benefit,
 perhaps at beaches only slightly degraded and needing
 only minimal cleanup before they are restored, or at
 beaches  in heavily populated areas where many people
 could benefit from restoration of the water body. Goals
 and objectives can be  set for restoration of affected
 resources, but protection of existing uses is as valid a
 goal as restoration.

 Methods  of problem assessment, presented in the
 following  sections, use  the criteria discussed in this
 section as a basis for comparison  and evaluation.

 Pollutant Source Assessments

 Pollutant   source  assessments   address  the  type,
 magnitude, and transport mode of pollution  sources
 (existing or potential) in  a watershed or program area.
 These assessments are  frequently  aimed at quantifying
 the  source flows  and pollutant loads under various
 conditions.

 Source Determination and Data Evaluation

 Urban runoff pollution sources can  be defined using the
 watershed description (Chapter 4) and other information
 such as  the type(s) of pollution affecting a  water
 resource,  the  pollutant transport mechanisms, the
 characteristics   of drainage  patterns  and  drainage
 structures, and the land uses in  the program area.
 Activities  or land uses within  a watershed that are, or
 potentially could be, causing pollution problems need to
 be identified. Pollutant types found in the watershed can
 provide clues regarding the source(s) of the  problems.
To isolate pollution sources, the  watershed  can  be
divided into smaller areas so that individual pollution
sources can be tracked  down. Depending on the size
of the watershed,  a drainage basin can first be divided
into sub-basins, which can, if necessary, be divided into
individual   tributaries,  pipe  systems, or  -drainage
channels.   Pollutant  types  typically  associated  with
certain activities or land uses are  listed in Table 6-2,
                                                    76

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This information  can be used  to identify  potential
sources. Problem sources can also be identified based
on  resource conditions, such  as eutrophication  of  a
water  body resulting  from excessive  nutrients,  or
closures of shellfish beds because of high  levels of
bacteria. In addition, sediments from aquatic systems
and storm sewers can provide useful information for
identifying potential sources (U.S. EPA,  1991 a).

Pollutant Source Flow and Load Estimation

Computer modeling is valuable in quantifying the flows
and loads of  pollution sources  needed  for pollution
source assessments. Models can be used to estimate
source  strengths  as  well  as  to  evaluate   the
effectiveness  of  proposed  corrective measures  or
BMPs. Models available for urban runoff assessments
vary  widely   in  complexity,  ranging  from  simple
estimation techniques to sophisticated and expensive
computer models. The following discussion highlights a
number of  commonly  used  methods,  focusing on
models used to  predict pollution characteristics in an
urban   environment.   Information  on   urban  and
non-urban models is available from literature (U.S.  EPA,
1987b,1991b;  Nix,  1991; Walesh, 1989) and  from
agencies that  sponsor the models. Methods of urban
runoff modeling  discussed in this  section include the
constant  concentration   or  unit   load estimates,
preliminary screening  procedure,  statistical  method,
universal soil loss equation,  rating-curve or regression
approaches,  and  hydrologic  and  pollutant  buildup-
washoff models.

Constant Concentration or Unit Load Estimates
Constant concentrations or unit pollutant  loads, which
can be used to estimate pollutant source loads, can be
obtained from  available data or estimated  based on the
types and sizes of land uses in the watershed. Constant
concentrations can  be coupled with  runoff volume
estimates to calculate runoff loads or can be used  in
hydrologic models to calculate time variable flows and
loads. The constant concentration or unit load method
is easy to use, and can be helpful as a first-cut estimate
to identify which areas within a watershed contribute the
largest  pollutant loads. Wet-weather and dry-weather
conditions  can   also  be  evaluated  separately,   to
determine the relative contributions of pollutants during
these weather periods. This method can  be facilitated
using  a  GIS with  information such as wet- and
dry-weather  pollutant  concentrations  from  different
sources, land use or source boundaries, and quantities
of flow produced in each area. Constant concentrations
or  unit loads  can  also  be  estimated  using  a
spreadsheet.
EPA's Nationwide  Urban  Runoff  Program (NURP),
conducted from 1978 to 1983,  is one example of a
comprehensive study  of storm  water  runoff  from
residential,  commercial,  and light  industrial  areas
throughout the United States. It contains  a large data
base of pollutant  concentrations and loads measured
during various storm events (U.S. EPA, 1983a). Other
data bases of storm water pollutant concentrations and
loads include  Driver and Tasker  (1990);  Tasker and
Driver (1988); and U.S. EPA, 1974, 1977,1982a, 1990.
Such data bases, however, must be used cautiously.
For example, since the NURP data are based largely
on areas without sanitary waste or industrial  waste
influences, they  might not be representative of the
location being studied.
These  types of data can be applied to  source load
estimation  techniques   such   as   the  constant
concentration or unit load method. For example, Table
6-3 presents median and mean values of event mean
concentrations (EMCs) derived from urban runoff from
EPA's NURP study  (U.S. EPA, 1983a). Typical ranges
of concentrations  of various pollutants found in rainfall,
storm water, combined wastewater, and wastewater
effluent  are  presented  in  Table 6-4.  With  the
aforementioned cautions, such values can be used as
first-cut estimates of pollutant loadings.  Because of the
high  variability   of  urban   runoff  data,  however,
site-specific data are required to ensure the accuracy of
this or other methods.
Table 6-3. Water Quality Characteristics of Urban Runoff for
         the NURP Site (U.S. EPA, 1983a; Adapted from
         Novotny, 1992)

                           Site Median    Site Mean
                           Event Mean    Event Mean
Constituents
Total suspended solids, mg/L
Biochemical oxygen demand
(5-day), mg/L
Chemical oxygen demand, mg/L
Total phosphorus, mg/L
Soluble phosphorus, mg/L
Total Kjeldahl nitrogen, mg/L
Nitrate and nitrite nitrogen, mg/L
Total copper, fig/L
Total lead, ng/L
Total zinc, jig/L
Concentration
100
9
65
0.33
0.12
1.50
0.68
34
144
160
Concentration
141 to 224
10 to 13
73 to 92
0.37 to 0.47
0.13 to 0.17
1.68 to 2.12
0.76 to 0.96
38 to 48
161 to 204
179 to 226
Table  6-5  shows  an  example  of  the  constant
concentration method used to estimate loadings of fecal
coliform  bacteria and nitrate-nitrogen  and to prioritize
nonpoint sources in a watershed.  To estimate the
loadings, mean concentrations for different land uses
were multiplied by the estimated annual runoff volume.
                                                   79

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Tab)* 6-4.  Charactarlatics of Rainfall, Storm Water, Combined Wastewater, and Treated Effluent (Adapted from various sources;
           so* Metcalf & Eddy, Inc., 1991; Novotny, 1992)
PanurMttr Rainfall
Suspended solids, mg/L —
Biochemical oxygen demand 1 to 13
(5-day), mg/L
Chemical oxygen demand, mg/L 9 to 16
Fecal coliform bacteria, —
MPN/100 mL
Total phosphorus, mg/L 0.02 to 0.15
Total nitrogen, mg/L —
Total KjoWahl nitrogen, mg/L —
Nitrate nitrogen, mg/L 0.05 to 1.0
Total lead, pg/L 30 to 70
* Average value.
Storm Water
141 to 224
10 to 13
73 to 92
Combined
Wastewater
.,270 to 550
60 to 220
260 to 480
Primary
Effluent
40 to 120
70 to 200
165 to 600
Secondary
Effluent
10. to 30
15 to 45
. 25 to 80
1,000 to 21 ,000 200,000 to 1,1 00,000 — —
0.37 to 0.47
3 to 24
1.68 to 2.12
0 to 4.2
161 to 204

1.2 to 2.8
4 to 17
' —
— '
140 to 600

7.5*
35*
.— •
—
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30*
—
— "
—

T«Wt 6-5. Estimated Urban Runoff Loadings Using Constant Concentrations (U.S. EPA, 1992)
Source Area,
ATM Description and Location , ac
A Main St and Freoport outlet stores 3.3
B Commercial development at I-95 30.6
Interchange, Main and Pine streets
C A portion of Freoport Crossing 13.9
outlets, Main St, Vamey Rd., and
KarKfean
D Main St., Vamey Rd., a portion of 21 .0
Unwood Rd., and adjacent
residential development
E1 Southern LL Bean parking lot 6.5
E2 Northern LL Bean parking lot 5.5
F Independence Way, Eastland Shoe 14.1
warehouse, Horsefeathers
Restaurant, and Main St
G Somerset Condominiums, Summer 38.0
St, Upper West St, and Freeport
Place Condominiums
H Municipal garage, Main St., and 15.0
town office parking lot
1 ' Downtown Village area along Main 19.2
St between Morse and West streets
including Oak
"Fecal coliform concentration = 16,000 org/100 mL,
6 Fecal coliform concentration = 17,000 org/100 mL,
° Fecal coliform concentration = 14,000 org/100 mL,
Fecal coliform concentration = 37,000 org/100 mL,
Annual
Runoff
% Runoff Volume,
Impervious Land Use- Coefficient Mgal
85 Commercial8
50 Commercial
60 Commercial
10 Multifamily
residential3
85 Industrial0
80 Industrial
20 Commercial
20 Single-" and
multifamily
residential
60 Industrial
Commercial
75 Commercial
0.73 2.7
0.45 15.7
0.61 9.7
0.13 3.1
0.73 5.4
0.69 4.3
0.21 3.4
0.21 9.1
0.53 9.1
0.65 14.2
Annual
Fecal
Coliform
Loading
org x 1fT2
(rank)
1.7(12)
9.8 (1)
6.0 (3)
2.0 (10)
2.8 (7)
2.2 (8)
2.1 (9)
•5.9 (4)
4.7 (5)
8.8 (2)
Annual
Nitrate
Nitrogen
Loading
Ib (rank)
14(11)
82 (1)
51 (4)
24 (8)
28 (7)
23 (9)
18 (10)
73 (3)
48 (5)
75 (2)
Quali-
tative
Ranking
Low
High
High
Low
Medium
Medium
Low
High
High
High
NO3-N concentration = 0.63 mg/L
NO3-N concentration = 0.96 mg/L
NO3-N concentration = 0.63 mg/L
NO3-N concentration = 0.96 mg/L
                                                          80

-------
 Runoff volumes were based on the size, irnperviousness,
 and land use of each source area. Table 6-5 presents
 the  estimated pollutant loadings  for the  watershed.
 Based on this analysis, 5 of the 10 areas (B, C, G, H,
 and I) of nonpoint source pollution were qualitatively
 assigned  ratings  of "high"  based on  their pollutant
 loadings. These areas contribute more than 75 percent
 of the total pollutant loading in the watershed.

 Preliminary Screening Procedure

 Simple equations  can be  used  to estimate annual
 average loading contributions of urban runoff for 5-day
 biochemical oxygen demand (BOD5), suspended solids,
 volatile solids, total phosphate phosphorus, and total
 nitrogen. The preliminary screening procedure is a
 sophisticated unit load method which can be  used to
 calculate unit loads as a function of land use, population
 density, and frequency of street sweepings (U.S. EPA,
 1982b). Pollutant loadings can be  estimated based on
 the relative contribution  of  pollutants from each land
 use; however, the  equations are not location  specific
 and are useful, only for screening purposes. Using the
 preliminary  screening  procedure,  unit  loads  are
 calculated by the following equation developed by EPA
 (U.S. EPA, 1976a) as reported by Walesh (1989):

             L = u(i,j)xPxPDFxSWF

 where:
     L = average annual amount of pollutant j
        generated per unit of land use  i, Ib/ac/yr
  u(i,j) = load of pollutant j generated per
        unit of runoff from land use i, in
        Ib/acre-inch
     P = average annual precipitation, in
  PDF = population density factor,  a dimensionless
        parameter with a value for residential
        areas of 0.142 + (0.218)(PD)°-5*,
        where PD is a population density in
        persons per acre, equal to 1.0  for
        commercial and industrial areas, and
        0.142 for institutional areas (e.g., parks,
        cemeteries, and schools)
 SWF = street-sweeping factor, a dimensionless
        parameter; SWF =1.0 when streets are
        swept infrequently,  with the average time
        between street sweepings being greater
        than 20 days; for more frequent street
        sweeping, SWF is less than 1.0 and could
        be estimated from site-specific  data or
        literature values.


The unit pollutant loads (u) are obtained from measured
or estimated concentrations  or loadings from  various
land use or source areas.
Statistical Method

The  statistical  method  of  modeling  urban  runoff
assumes that EMCs are distributed log-normally and
characterizes EMCs by their  median values and their
coefficients of variation. EPA's statistical method (U.S.
EPA, 1979) includes  statistical properties of rainfall,
area, runoff coefficients, median EMCs, and coefficients
of variation of EMCs of various pollutants. The Federal
Highway  Administration  (FHWA)  has  implemented
EPA's statistical method  for  various locations  in  the
United States (Driscoll et al., 1989; Woodward-Clyde
Consultants, 1990a).

The runoff flow rate and volume from a mean event are
computed  by the FHWA model using  the following
equations:

       MQR = Rv x MIP x ARW x (3,630/3,600)    <;

          MVR = Rv x MVP x ARW x 3,630

where:
 MQR = average runoff flow rate for mean storm
        events, ftVs
   Rv = runoff coefficient  (ratio of runoff to rainfall),
        equal to 0.007 x  IMP + 0.10, where IMP is
        equal to the impervious fraction of the
        drainage area, %
  MIP = rainfall intensity for mean storm event, in/fir
ARW = drainage area of  the highway segment, ac
 MVR = volume of runoff for mean storm event, ft3
 MVP = rainfall volume for mean storm event, in

The  numbers  3,630  and  3,600  are  dimensional
conversion factors.

The log-normally distributed EMCs are calculated by the
equation:
                   = TCRV(1+CVC2)
where:
MCR = EMC for site, mg/L
 TCR = site median pollutant concentration, mg/L
 CVC = coefficient of variation of EMCs

and the mean event mass load is computed by:

      M(MASS) = MCR x MVR x (62.45 x 1 0"6)

where:
M(MASS) = mean pollutant mass loading Ib/event
    MCR = mean runoff concentration, mg/L     ,
    MVR = mean storm event runoff volume, ft3
   i-        •      i    -      . •        ..'•;"
Universal Soil Loss Equation

The Universal Soil Loss Equation is primarily applicable
to agricultural areas and is used to estimate the soil loss
                                                  81

-------
and sediment yield from a homogeneous parcel of land
(U.S. EPA, 1976b). The discussion in this handbook is
general, and more detailed information can be obtained
from referring to  more specific sources (SCS, 1977).
This method, relatively simple to  use, considers such
factors  as rainfall, erosive forces of the rainfall,  soil
erodibility, slope, vegetative cover, and erosion control
practices.  Since  this  method is used primarily to
estimate soil  loss and, when modified, sediment yields
from non-urban, agricultural areas, it is less applicable
to the problems addressed in this  handbook than other
methods discussed.

The Universal Soil Loss Equation  is:

             E = AxRxKxLSxCxP

where:
  E = soil loss by water erosion in rill and inter-rill
     areas, tons/yr
  A = area, ac
  R = rainfall factor, accounting for erosive forces of
     rainfall and  runoff, erosion index units/yr
  K a soil erodibility factor reflecting the physical and
     chemical properties of a particular soil,
     tons/ac/erosion unit index
LS a slope length or topographic factor reflecting the
     influence of vegetation and mulch,
     dimensionless
  C - cover and management factor reflecting the
     influence of vegetation and mulch,
     dfmensionless
  P = erosion control practice factor that is similar to
     the cover-management factor, but accounts for
     practices on the land surface such as
     contouring, terracing, compacting,
     sedimentation basins and control structures,
     dimensionless
In order to estimate sediment yield (as opposed to soil
loss), the equation is modified by adding a sediment
delivery ratio  (Sa) as follows:
         Y(S)E = AxRxKxLSxCxPxSd

where:
Y(S)g = sediment loading to stream, tons/yr
   S . . . Xn  x BCF
where:      A
            Y = estimated storm-runoff load or
                volume, response variable
  Po. Pi. Pz. Pn = regression coefficients, provided by
                Driver and Tasker, 1990
 X0, X17 X2, X3 = physical, land use, or climatic
                characteristics, explanatory variables
         BCF = bias-correction factor, calculated by
                Driver and Tasker, 1990

Hydroiogic and Pollutant Buildup-Washoff Models

For  larger and  more complex programs,  it  may  be
desirable  to  use  hydrologic  and pollutant  buildup-
washoff models. These models address the accumulation
of pollutants  during  dry-weather periods and  the
washing off of these pollutants during rainfall events. Of
the many models available,  some of the more widely
used models that use a buildup-washoff  mechanism
include Hydrological   Simulation  Program — Fortran,
HSPF  (U.S.  EPA, 1981); Storm  Water Management
Model, SWMM (U.S. EPA, 1988b); Storage, Treatment,
Overflow, Runoff Model, STORM;  and Source Loading
and  Management Model, SLAMM (Pitt,  1989). These
models are described below. Table 6-6 compares these
urban hydrologic and pollutant buildup-washoff models
and the EPA statistical  method as implemented by the
FHWA. Many other models are available which are not
described here.

HSPF, available from EPA,  simulates movement and
storage of water in the hydrologic budget of a watershed
or drainage  basin,  from  rainfall to  streamflow  to
ground-water storage.  HSPF is  useful  when  large
watersheds comprising multiple  pollutants and  land
uses are to be modeled and/or when issues  such  as
sediment  erosion, pollutant interaction, and  ground-
water quality of the system are of concern. Input data
requirements  of  this model are extensive and include
time series inputs of hydrologic and meteorologic data,
and  input of  characteristics  describing  pollutants,
topography, storage, response, and evapotranspiration.
HSPF can simulate  receiving waters and pervious and
                                                  82

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 Table 6-6.  Comparison of Urban Runoff Model!! (U.S. EPA, 1991 c; Pitt, 1989)
                                                                                 Model
Attribute
Sponsoring Agency

Type of Method
Surface water— simple
Surface water— refined
Soil/ground water— simple
Soil/ground water— refined
Surface water— statistical
Simulation Type
Continuous
Single event
Hydraulic/Hydrologic Features
Rainfall/runoff analysis
Sewer system flow routing
Full, dynamic flow routing
Surcharge
Regulators, overflow structures
Storage analysis
Predicted Pollutant Concentrations in:
Runoff water
Surface water
Ground water
Predicted Pollutants
Conventional
Organic
Metals
Number of pollutants
Source/Release Types
Continuous
. Intermittent
Single
Multiple
Diffuse
Unique Features
Special solids routines
Treatment analysis
Degradation products
Data base
Uncertainty analysis
Input/execution manager
Level of Application
Screening
Intermediate
Detailed (suitable for design)
Data and Personnel Requirements8
Overall Model Complexity1
Available on Microcomputer
Storm Water
Management
Model (SWMM)
EPA



X
X



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X
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X
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Impervious lands and soils. Although it is complicated,
model documentation is available from EPA, including
copies of the model, user assistance,  and periodic
training sessions (U.S. EPA, 1991d).
SWMM  Is a  complex model using  finite-difference
approaches that can be used to simulate urban storm
water runoff and combined sewer overflows. Input data
requirements are extensive and  involve information
such as precipitation, air temperature, channel and pipe
networks, land use patterns, and storage and treatment
facilities (U.S EPA, 1991d). SWMM can be used during
both the planning and design phases of a program. Its
output consists of  hydrographs,  pollutographs, and
control options and cost (U.S. EPA,  1991d). Model
documentation is available from EPA.
While the use of SWMM and HSPF requires a high level
of effort and expertise, the models also lend themselves
to more simplified treatment and simplified versions are
available. For example, in SWMM, the  buildup-washoff
method of estimating pollutant contribution to a system
can be substituted with constant pollutant concentrations.
SWMM can also be run in a long-term mode using
variable   time  steps  so  both  event-specific  and
seasonal/annual conditions can be analyzed.

STORM contains simplified hydroiogic and water quality
routines   for  urban  runoff  modeling. While data
requirements of the model  are minimal, the model is
less flexible than  other, more complex models. Output
of STORM includes storm event summaries of runoff
volume,   concentrations  and  loads,  storage  and
treatment utilization,  and  total overflow  loads and
concentrations (U.S.  EPA,   1991d).  Although  the
simplicity of STORM makes it an attractive model for
screening purposes, it has not been updated  by  its
agency sponsor,  the U.S. Army Corps  of Engineers,
Hydroiogic Engineering Center (HEC), since  1977.
While the model has  been  updated  and refined  by
private entities and  many applications of STORM exist,
use of STORM has  declined in recent years (U.S. EPA,
1991d).
SLAMM  is a proprietary model which  can be used to
evaluate the effects of pollution control measures and
development characteristics on urban runoff quality and
quantity.  Model  input requirements  include rainfall
duration, depth of rainfall, areas of each pollution source
type, SCS  soil  types,  building   density,  land use,
pavement texture, traffic density,  and roof  pitch (Pitt,
1989). The SLAMM model user manual incorporates a
discussion of the hydrology of small storm events and
its  relationship to more "standard" hydroiogic models.
Investigations have shown the need to represent the
rainfall-runoff processes correctly for the more frequent,
smaller size storms since they often account for a major
part of the pollution loading (Pitt,  1989). Output of the
SLAMM  model includes, for each rain and land use,
matrices describing  source  area and outfall flow
volumes, paniculate residue mass and concentrations,
and relative contributions from each rainfall event (Pitt,
1989).
While many other models  are also  available, some
receive  little or no support from their sponsoring parties
and/or have not been widely used. Other widely used
models  can simulate hydrology but not pollutant buildup
and washoff. Such models include TR20 (SCS, 1969)
and  HEC1  (Hydroiogic  Engineering Center,  1990).
These hydroiogic models are  not discussed in detail
here; model documentation and references contain the
specific hydroiogic calculations used.

Hydroiogic models, such  as TR20 and  HEC1, can be
used to generate time-varying runoff flows for one  or
more storm events  using   rainfall  and  watershed
characteristics  as model inputs. To generate urban
runoff pollutant loads, the hydroiogic output (flow versus
time) from  the  models  could  be combined  with
estimated  urban  runoff  concentrations.  For some
applications, for  example sizing of BMPs  such  as
detention ponds, only a hydroiogic model is needed.

 Transport Characteristics Determination

 In addition to the magnitude of a pollutant  load, the
 location of a pollution source with respect to the affected
 resource, the  mode of transport to the resource and
 degradation of the pollutant should also  be considered.
 For example, sources with a clear path  to a waterway,
 such as pipes, ditches and gulleys, are more likely to
 cause adverse effects in a receiving water than similar
 sources that must travel through natural filters such  as
 forested or grassy areas before entering  a surface water
 body.  Changes  in  loads,  from  the   initial  source
 discharge to the  point where they affect the receptor,
 occur because of such factors as travel time, dilution,
 soil   infiltration, and  decay.   Fate  and transport  of
 pollutants  can  be  modeled  using hydroiogic and
 pollutant  buildup-washoff models which  attempt  to
 account for these factors deterministically. Since the
 simpler methods (i.e., unit load or statistical) can only
 empirically  estimate  these  factors,  the  level  of
 uncertainty and error is likely to be higher. The level of
 uncertainty  is high even with  the deterministic models,
 though. Site-specific data is thus important to validate
 any tool which is used.

 Resource Assessments

 Resource assessments address the impact of pollutant
 sources on the resources of interest—taking the results
 of the  pollutant source assessments (described in the
 previous section of this chapter) and determining the
 effect of these pollutant sources on water resources.
 Assessments,  however,  can  be conducted on  other
 ecological aspects  of a watershed, as well. Water
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resources can include water quality as well as aquatic
life, sediment, and other characteristics of the water
bodies. Methods to perform resource assessments can
range  from  evaluation of  water quality data  and
comparison with criteria, to mathematical  modeling of
receiving waters. These methods are described further
in this section.

Basic Data  Evaluation

Urban runoff  problems can be identified by evaluating
available  and  newly  collected data.  Evaluation of
available  data is  conducted  with  numerous  tools,
including   spreadsheets,    database   management
systems, GIS, statistical analysis (described in Chapter
5),  and  mathematical models  (described  in  this
chapter).  The data  are  compared  to  acceptable
resource criteria to determine the existence  and severity
of problems.

A useful measure of the condition of a specific water
resource is comparing its water quality, sediment, or
biological data with state water quality standards or EPA
water quality criteria.  State  water quality standards
define the quality of water that supports  a particular
designated use. EPA publishes water quality criteria that
consists   of   scientific  information  regarding  the
concentrations  of specific chemicals  in  water  that
protect  species against adverse  acute  (short-term)
effects  on  sensitive   aquatic organisms,  chronic
(long-term) effects on aquatic organisms, and effects on
human health from drinking water and eating fish (U.S.
EPA, 1986). These criteria, often  based on results of
toxicity testing of sensitive species, are intended to be
protective of all species. Section 304(a)(1) of the Clean
Water Act requires  EPA to  publish and  periodically
update these criteria.

The Safe Drinking Water Act of 1974, established to
protect public drinking-water supplies, requires EPA to
publish  maximum contaminant level goals (MCLGs),
which are non-enforceable levels at which there are no
known or  anticipated  health effects, and maximum
contaminant  levels  (MCLs),  which  are  enforceable
levels, based  on best technology, treatment techniques,
and other  factors including cost. Updates to federal
criteria are announced  in Federal Register notices.

States have  surface  water  standards that  classify
surface  water bodies  into use categories, establish
instream levels necessary to  support these uses, and
define    policies   regarding    the   protection   and
enhancement of  these water resources. EPA  can
establish water quality standards (40 CFR 131) for toxic
pollutants in  states and territories that have  not fully
adopted their own standards. In addition, many states
have ground-water standards that designate  uses for
various   ground  waters,  and  water  quality  levels
necessary   to   sustain  these   uses  and   protect
ground-water quality.

The interpretation of sediment chemistry results is not
straightforward. A number  of approaches have been
used  to evaluate  the  degree  of contamination in
sediments (Maughan, 1993). Many of these approaches
have been developed to determine impacts associated
with dredging activities (U.S. EPA and  U.S.  ACOE,
1991). EPA is developing criteria for sediment similar to
those for water quality for certain organic compounds
(U.S.  EPA,  1988c). An important  factor  affecting the
development of  these  criteria is the bioavailabiiity or
toxicity risk to aquatic organisms due to a contaminant
in undisturbed sediment.  Since this bioavailabiiity is
influenced by the physical and chemical nature of the
sediment, toxic  effects  which might be  seen at low
concentrations in some sediment types might not be
evident in others.

To take the  variability due to sediment characteristics
into    account,   contaminant   concentrations   are
normalized  through  equilibrium  partitioning between
particulate and liquid (pore water) phases, after which
EPA  water  quality  criteria  are used  to  assess
environmental   or   human  health   risks.   Further
development of sediment criteria for inorganics, such as
metals, is  anticipated. Until sediment  criteria  are
finalized, much of the evaluation of sediment chemistry
data is accomplished on a relative basis by comparing
the results from  upstream and downstream stations to
determine if  elevated levels of contaminants exist, or by
comparing   results  to  other  areas  where  data  are
available.

Ecological effects can be assessed by examining the
biological community structure. Specific parameters to
consider include the relative abundance of pollution-
tolerant and pollution-sensitive  species  as  well  as
common  indices   including,  but  not   limited   to,
Shannon-Weiner diversity, Simpson's dominance, and
evenness (Pielou, 1975) as discussed in Chapter 5.
Various types of biological  criteria  or  indices  are
available from  the literature  and can  be  used for
comparative purposes.  An  example of the  use of
biocriteria to evaluate data is the State of Ohio biotic
index,  which has been used to assess the condition of
the biota of  rivers and streams since 1978 (U.S. EPA,
1991e). Ohio's use of biocriteria is described in the case
study at the  end  of this chapter.

Receiving-Water Modeling

Receiving-water  models are used to assess existing
conditions and to simulate future conditions of a water
resource under various pollution prevention and control
scenarios. They can also be used to assess the impact
of alternative BMPs (Chapter 8). These models receive
input   from   runoff  model  results,  field-measured
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parameters,  and values of parameters found  in the
literature. The level of complexity of the receiving-water
model chosen should parallel that of the model used to
assess urban runoff flows and loads. Some commonly
used receiving  water models include the Enhanced
Stream  Water Quality Model (QUAL2E),  the  Water
Quality Analysis Simulation Program (WASP4), and the
Exposure Analysis Modeling System II (EXAMSII), as
summarized in Table  6-7 and described in more detail
below.  In  addition,  HSPF,  discussed above,  has a
receiving-water  model component.  These  models,
along with  the  SWMM  model, are available from
ERA'S  Center for Exposure Assessment Modeling,
Environmental Research Laboratory, in Athens, Georgia.

QUAL2E can  be used either as  a steady-state or
quasi-dynamic model  to simulate conditions  of rivers
with multiple headwaters, waste discharges, tributaries,
withdrawals,  dams,   and  incremental  inflows  and
outflows. The model  can simulate  15 water quality
constituents, including dissolved oxygen,  biochemical
oxygen demand, temperature, nitrogen and phosphorus
species, cdifomns, arbitrary nonconservative constituents,
and conservative  constituents   (U.S. EPA,  1987c).
QUAL2E-UNCAS is an enhancement to QUAL2E which
allows the user to perform uncertainty analysis on the
effects of model sensitivities and uncertain input  data
on model forecasts (U.S.  EPA, 1987c). Three types of
uncertainty analyses are available: sensitivity analysis,
first-order error analysis, and Monte Carlo simulation.
Using this model, the user can determine input factors
that contribute the most to the model's uncertainly and
the level of risk associated with model predictions.  Both
QUAL2E and QUAL2E-UNCAS are supported by  EPA
and are well documented.
The modeling  framework   of  WASP4   provides  a
flexible-compartment  modeling approach, applicable in
one, two, and three dimensions, which can be used to
simulate contaminant fate in surface water. WASP4 is
structured to allow the easy substitution of user-written
subroutines  into the  model. Thus, a range  of water
quality problems can  be  simulated by WASP4 using
either one of the model's  kinetic subroutines or a
subroutine written by the user. The model can be used
to simulate  biochemical  oxygen demand, dissolved
oxygen,   nutrients   and   eutrophication,   bacterial
contamination, and toxic chemicals in the sediment bed
and in the overlying waters. In addition, WASP4 can be
linked to other models, such as DYNHYD5, a simple
model  that simulates variable tidal cycles, wind and
unsteady flows, ^MJhe Food  Chain Model,  which
predicts pollutant uptake and distribution throughout an
aquatic food chain (U.S. EPA, undated).

EXAMSII performs evaluations and error analyses of
the fate of synthetic organic  chemicals based on
user-specified properties of chemicals and ecosystems,
such as descriptions of a system's external loadings,
transport processes and  transformation  processes.
Model   predictions   include   chemical   exposure,
consisting of long-term chronic, 24-hour  acute,  and
96-hour acute concentrations; fate, consisting of the
distribution of chemicals in the system and the relative
dominance  of  each transport  and  transformation
process; and persistence, the time required for effective
purification of the system  once the loading has ended
(U.S. EPA, undated).

Model Selection

Selection  of receiving water models for  resource
assessments (or of urban runoff models for pollutant
source assessments) depends on considerations such
as available input data, project  requirements, budget
constraints,  and user preference and  familiarity.  It is
sometimes useful to choose a simple or screening level
model at first to identify major pollutant impacts or loads
for  which  preliminary control  measures  could  be
implemented. A more complex model can then be
selected  if more  detailed analyses of the  impact  of
pollutants and  the  effect  of  alternative  corrective
measures are required. Since model  simulations can
help in selecting pollution prevention and  treatment
measures (and thus, in allocating of limited funding), the
user should  have experience with the model to ensure
that the model predictions are correct. An understanding
of the selected model and  its capabilities and limitations
is critical.

In 1976,  EPA compiled a list of  questions and factors
that should be considered when selecting a model (U.S.
EPA, 1976b). These considerations, which can be used
to select either urban runoff or receiving water models,
are presented below.

To determine whether a model is required or could be
used, one could consider the following issues:

1. What is the problem to be solved?

2. What temporal resolution is required? Depending on
   the type  of  water quality problem and  receiving-
   water, single-event, seasonal, or long-term multiple-year
   calculations might be appropriate.

3. Is a model needed? If so, what approach  is necessary
   (e.g., computer program, hand calculations)? Would
   a gross assessment of relative loads and impacts
   on water quality suffice?

4. What input,  calibration,  and verification  data are
   available? The model  selected must be  calibrated
   and  verified, and adequate input  data  must be
   collected. If  data are not available, or if adequate
   funds for data collection are  not provided, the use
   of a complicated model could be ruled  out.
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Table 6-7.  Comparison of Receiving-Water Models (U.S. EPA, 1983b, 1985a,b)

                                                         Models
Attribute
Application
Dimensionality
State
Water column
transport
Sediment bed
condition
Sediment bed type
Unique features
Enhanced Stream
Water Quality Model
(QUAL2E)
River flow, well-mixed
lakes
One-dimensional
Steady-state
Quasi-dynamic
Advective and dispersive
Completely mixed
Stationary
UNCAS — Uncertainty
analyses of input
parameters on model
forecasts
Water Quality Analysis
Simulation Program (WASP4)
General — river flow, lakes,
estuaries, oceans
Three-dimensional
Time-varying
Advective and dispersive
Completely mixed
Stationary
TOXIC — models dissolved and
adsorbed chemical concentrations
EUTRO4— models DO, CBOD,
nutrients, phytoplankton
DYNHYD5— models tidal cycles,
wind, unsteady inflows
Food Chain model — simulates
uptake and distribution throughout
a food chain
Exposure Analysis
Modeling Systems II
(EXAMS II)
Nontidaf lakes
Three-dimensional
Steady-state
Advective and dispersive
Completely mixed
Simplified exchange
Stationary
Contaminant
transformation and
transport processes
Hydrological
Simulation
Program— Fortran
(HSPF)
Unstratified lakes
One-dimensional
Time-varying
Advective
Completely mixed,
sedimentation
Moving
ARM— Agricultural
runoff model
NFS— Nonpoint
source model
If a model is determined to be necessary, other factors
to consider include the following:

1. Regardless  of  the  method  selected,  personnel
   qualified in water quality analysis should be available.
   Any  model,  simple  or  complicated,  requires a
   considerable  amount of expert judgment in its
   application. Without this expertise, model application
,   likely will fail.

2. The major  costs in applying any computer-based
   model  are  related to becoming familiar with  the
   model, collecting basic data for model application
   (most of these data remain the same, regardless of
   the number of times the model is used), and setting
   up the model on the  local computer system. Thus,
   availability  of models that  previously have  been
   calibrated and applied locally should be considered.

Once it has been determined that a model will be used,
the  following  questions should be  considered  in
determining  whether  the  model is suitable  for  the
problem being studied.

1. What, if any, water quality  constituents  are to be
   modeled and can the model accommodate them?

2. Is the  problem  steady state or dynamic (i.e., do
   sources or conditions change over time)?

3. What are the spatial considerations? F:or streams, a
   one-dimensional model is adequate if homogeneous
   mixing across the river cross-section is an adequate
   assumption.  For an  estuary,  a two-  or three-
   dimensional model might be required.

4. Has  a model under consideration been used and
   tested?  Is  good,  user-oriented  documentation
   available?

5. If  a  proprietary  model is considered, how  will
   continuity in planning  be accommodated?  The
   planning process is ongoing, and models are most
   economical when used repeatedly.
6. What are the costs of model application? Computer
   costs are relatively insignificant; the major costs of
   model  use are personnel costs.

Model Validation

The input data file for a model used either for resource
assessment  or  pollutant  source  assessment  is
calibrated using values of parameters measured during
field  investigations  of the pollution sources  and/or
receiving-water system,  depending on  the type  of
modeling. Parameters to  be included as model input,
but that were not measured during field sampling, are
estimated and adjusted to provide a close fit of model
predictions to measured data. Values for parameters not
easily or  regularly  measured  can be obtained from
engineering and scientific publications. Often,  typical
values,  or "default values," for these parameters  are
presented in the model's user manual and can be used
in the initial phases  of model calibration.
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Model verification, the next step in the model validation
process, often involves using a second data set to verify
the accuracy of the calibrated model input.  Measured
parameters from the second data set are input to the
model and simulated levels  of parameters (such  as
dissolved oxygen concentration) are compared to actual
values  measured  during the second field sampling
survey.  Verification may be conducted qualitatively, by
visually comparing graphical  representations of the
model  simulation  and  actual  data.  In addition,  a
quantitative verification can be conducted through the
use  of simple statistical  comparisons.  Calibrated
parameters can be adjusted again, to ensure a good fit
between model predictions  and each  data  set. A
detailed discussion of the model validation procedure
was presented by U.S. EPA (1980).
Once the  urban runoff or receiving-water model has
been  validated, it can  be  used to simulate various
scenarios  of storm  events,  pollutant loadings, and
corrective  measures. Graphical presentation of model
results  is  an effective method for displaying model
simulations during evaluation  of results and in reports.
While computer modeling  is valuable for examining
existing conditions and simulating impacts due to future
changes, users should be aware that model predictions
are only as accurate as the quality of the data used;
some level of error is associated with even the best
modeling techniques.

Institutional Assessments
Assessment of the institutional constraints of a program
provides the managers with  perspective concerning the
nontechnical  issues  affecting  the  program.  The
institutional issues  of a program are  assessed  by
evaluating the program's potential and limitations and
by reviewing the requirements of involved agencies and
the public. One major institutional issue  that must  be
addressed on an urban runoff program is determining
the responsibilities of each involved party, especially for
programs involving multiple  agencies. Issues related to
the  control  of the   program  (e.g.,  enforcement,
maintenance, permitting, and funding) can  affect the
program's emphasis and the selection of its corrective
measures.  Another  institutional  issue  involves the
limitations of  available technology.  Implementability of
controls can also be considered, particularly in areas
involving limited access to  private properties.  The
potential for eliminating or reducing an urban runoff
problem or improving affected  water resources can also
be considered.  Questions and concerns of the public
might prove to be influential  during the decision-making
processes. Applicable  regulations  could force  the
sequencing  of  corrective  measures  so that those
addressing  compliance  with the  regulations   are
implemented first.
Goals and Objectives Assessments

The relative importance of an urban runoff problem can
be assessed by comparing it to the program's resource
and/or technology-based goals and the objectives of the
program's sponsor, as discussed  in Chapter 3. For
example, one water resource goal might be to "provide
improvements to water quality in areas where the most
people  will  benefit." Comparison  of  the  pollution
problems to such a goal provides the program team with
perspective on which problems to solve to achieve the
goal.  By  comparing  the  pollution  problems to the
program's goals and objectives, the program team can
identify and focus on problems that are compatible with
these goals. The  assessments conducted on pollutant
sources, water resources, and  institutional aspects
provide input to these determinations.

Problem Ranking

Since funding to  correct pollution problems is usually
limited, the sources or impacts to be addressed should
be prioritized to allow for targeting of limited resources.
While ranking is a subjective process that requires the
judgment of decision-makers, ranking systems can be
used to help develop priorities. A ranking methodology
can range from simple, descriptive methods (qualitative)
to numerically complex (quantitative), depending on
the urban  runoff program  objectives  and  funding
constraints. Ranking methods can apply to a variety of
geographic areas, ranging from counties or communities
with multiple watersheds to individual water bodies  or
pollution sources. Criteria such as those presented in
Table 6-1 can be used in problem ranking.

Ranking should be conducted  following  consultation
with involved parties, including local, state, and federal
agencies;  local  environmental groups; and concerned
citizens. Public opinion can have a large influence on
the ranking of  pollution problems. For example, the
public  might give priority  to controlling  sources that
discharge to a favorite pond used for swimming. Urban
runoff   control   programs  should  consider  public
concerns and desires when prioritizing problems, no
matter which type of ranking approach is employed.

Three types of ranking procedures, ranging from simple
to complex, are discussed  in this section.

Qualitative Ranking

The  simplest  ranking approach  uses  qualitative
rankings (e.g.,  high,  moderate,  or low)  to  prioritize
pollution problems such as in the  example presented in
Table 6-5. Other qualitative ranking methods use letters
(e.g., A, B, C) or  numbers (e.g.,  1, 2, 3) to develop a
relative scale for comparing problems. The qualitative
rankings must then be interpreted to determine which
problems should  be of  highest priority in developing
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controls. In the example in Table 6-5, the qualitative rank
is based on estimated pollutant load. Other measures
can also be  used as a basis for qualitative  rankings
{e.g.,  level of public concern or the importance of the
use to be protected).

Numerical Ranking

To  perform  numerical   ranking,  rating  points  are
assigned to each  ranking criterion for each problem.
Each  ranking criterion is assigned a weight based on its
importance relative to the  other criteria. The rating
points are then multiplied by the relative weight. AH of
the products  (i.e., criterion rating x relative weight) are
summed for  a given problem. This procedure is then
repeated for all the problems being evaluated. The
sums thus assigned are  compared and the problems
with the highest sums receive the highest priority during
implementation of urban runoff controls.

In an example of a numerical  ranking  system for
prioritizing pollution sources (Woodward-Clyde Consultants,
1990b), a hypothetical  application of this  weighted
ranking methodology uses the following criteria: water
body  importance (as reflected by stream or lake size),
type of use (ranging from urban drainage to recreational
contact), status of use (impaired versus denied), level
of use  (low,  moderate or high),  pollutant loads (not
actual loads but estimates for comparative purposes),
and implementability of controls (based on institutional
factors, existing ordinances, or technical  considerations).
These criteria are similar to some identified in Table 6-1.
The relative importance of each criterion is designated
by assigning  a weight appropriate for the site-specific
conditions of the watershed under consideration. The
sum of all weights  used to rank the problems equals
100. Next, for each problem, the criteria are ranked
using a suggested range  of 1  to 9, with  a  higher
numerical ranking indicating a higher need for corrective
action. This listing  allows relative comparisons to be
made among problems with respect to a single criterion.

A hypothetical  urban watershed, consisting  of three
streams and  several types of land use, illustrates this
numerical ranking  method  for prioritizing   pollution
problems  (Figure   6-1).  Information  describing  the
system is presented  in Tables 6-8 and  6-9. Typical
sources for  these  data  include site-specific pollutant
loading data, model results, and literature values from
data bases  such  as those  identified earlier in,this
chapter. There are four criteria of equal weight: stream
size,  beneficial  use, pollutant load,  and ability  to
implement (Table 6-10).  The three "use" criteria are
clustered together as subcriteria of the "beneficial use"
criterion.

Ranking for "stream size" is determined based on the
total drainage  area of each  of the three streams.
Consistent  with  the   goals  for  the  hypothetical
watershed, Stream C is ranked highest with respect to
"type of use" because of its recreational uses in the city
park; because  it is used mainly as an urban  drain,
Stream B  receives the lowest ranking; and Stream A is
ranked  between the other two streams because  it is
used to support aquatic life. With respect to "status of
use,"  Stream  A  ranks  highest  because although
somewhat impaired, it has the potential to be improved
by control of pollution sources. Stream B receives a low
ranking for use status because its water quality is poor
and its function  as part of an urban drainage system has
long been accepted.  Stream C also receives  a low
ranking for use  status since the water is of high quality.
Rankings for "level of use" reflect the number of people
using or affected by each stream.

Mass pollutant  loadings are calculated based on runoff
coefficients  (functions  of the  amount  of impervious
area),  runoff concentrations of  pollutants, and  the
amount of land use type in each stream's drainage area.
Each stream is ranked  based on the proportion of
pollutant load from its watershed  (in this example, total
suspended solids is used). The watershed of Stream B
is judged  easiest to implement controls because  it is
predominantly  industrial.  Based  on  the  method
presented  in this example, Stream C's  watershed
should  receive  priority  during   implementation  of
controls, followed by Stream A's and then Stream B's.

Quantitative Ranking

A fully quantitative ranking of urban runoff problems also
could be performed using pollutant source assessment
methods such  as  urban  runoff models and resource
assessment methods such as receiving-water models.
Quantitative ranking requires the greatest  amount of
resources. For this approach, the models would be used
to determine which  pollution sources contribute the
greatest impacts by  testing various load  reduction
scenarios. Through such evaluations, critical  problem
sources or  impacts  could be prioritized.  Chapter 8,
which concerns selection of BMPs, discusses this type
of approach further.
                                                   89

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                    Stream C
                           Open   . .^^	
                         (developing)
            Stream A
Figure 6-1.  Schematic representation of watershed (Woodward-Clyde Consultants, 1990b).
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Table 6-8.  Characteristics of the Targeted Areas and Estimated Concentration Loads (Woodward-Clyde Consultants, 1990b)
                                      Average Concentration in Runoff, mg/L                   Drainage Area, ac
Land Use
Category
Industrial
Commercial
Residential (high
density)
Residential (low
density)
Open — developing
Open— urban park
Total urban area
Upstream
drainage area
Total drainage area
Runoff
Coefficient
0.6
0.8
0.4
0.2
0.1
0.1



Total
Suspended
Solids
120
80
90
100
150
50



Oil and
Grease
20
15
10
5
0
0



Total
Petroleum
0.20
0.20
0.40
0.60
0.80
0.80



Copper
0.05
0.05
0.04
0.03
0.01
0.01



Stream
A
0
1°
100
200
0
0
310
600
910
Stream
B
150
80
100
0
0
0
330
0
330
Stream
C
0
110
50
200
150
50
560
20,000
20,560
Urban
Total
150
200
250
400
150
50
1,200
20,600
21,800
                 Table 6-9.  Estimated Total Suspended Solids Loads for Targeted Areas (Woodward-Clyde
                            Consultants, 1990b]i
                                                         Total Suspended Solids, Ib/in of rain
Land Use Category
Industrial
Commercial
Residential (high density)
Residential (low density)
Open — developing
Open — urban park
Watershed total
Watershed rank value
Stream A
0
145
817
908
0
0
1,870
1.7
Stream B
2,452
1,162
817
0
0
0
4,431
4.1
Stream C
0
1,598
409
908
511
57
3,482
3.2
Urban Total
2,452
2,906
2,043
1,816
511
57
9,784
9.0
Table 6-10.  Prioritization Analysis for Urban Area Targeting (Woodward-Clyde Consultants, 1990b)
                                                 Beneficial Use
Urban Watershed
Weights
Watershed A
Watershed B
Watershed C
Total urban watershed
stream
Size
25
4
2
8
8
Type
10
5
2
8
8
Status
10
7
2
2
5
Level
5
4
1
6
8
pollutant
Load (TSS)
25
1.7
4.1
3.2
9.0
Ability to
Implement
25
5
7
3
2
Target
Score*
100
4.08
3.73
4.85
6.45
* Target score = weighted average of rank points = sum (rank score x weight)/sum (weight)
                                                           91

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                                       Case Study:
                      Ohio Environmental Protection Agency
              Biological  Criteria for the Protection of Aquatic Life
 Background

 Since 1978, the Ohio Environmental Protection Agency (Ohio EPA) has been assessing the biota of
 rivers and streams as part of its basic monitoring strategy. This biomonitoring program was developed
 for Ohio's fishable waters in response to aquatic life goals of the Clean Water Act. Originally, biocriteria
 were used to assess the effects of wastewater treatment plant discharges on aquatic life throughout the
 state. Then, with the increased emphasis on addressing storm water runoff and NPS pollution sources,
 the Ohio ERA has begun using biomonitoring for these sources.

 The use of biocriteria to assess a water body's overall health has several advantages over more common
 chemical analysis of receiving waters, including (Ohio EPA, 1987):

 • The fish and macroinvertebrates sampled inhabit the receiving water continuously.

 • The effects of past events (e.g., floods and droughts) are considered.
 • Cumulative impacts can be  seen.

 • The species used have a long life span.

 • The species allow a direct measure of CWA's biological goals.

 The traditional approach of water chemistry analysis results in a snapshot of the receiving-water body
 at the time of sampling.  For a more complete picture, numerous sampling events are required, which
 can be very costly. Biocriteria analysis, however, gives a cost-effective assessment, although somewhat
 qualitative,  of the water body and its ability to support aquatic life.

 Analysis Methods

 In developing biocriteria,  the state was divided into five different ecoregions with generally homogeneous
 characteristics. Within each ecoregion,  water bodies were selected as "regional reference sites" to
 represent "least impacted" conditions. Rather than represent pristine conditions, these sites were
 selected based on the amount of stream channel modification, the condition of the vegetative riparian
 buffer, water volume, obvious  color/odor problems, and general representativeness. Once these sites
 were selected, fish and  macroinvertebrate sampling programs were implemented to determine water
 body characteristics and to obtain information  required to develop quantifiable criteria to compare with
 the health of othefwatefbodies. Three water Body health indices were developed from the sampling data:
 • Index of biotic integrity (IBI)

 • Modified  index of well  being (Mlwb)
• Invertebrate community index

The IBI and Mlwb are used to assess fish community health, and the ICI is used in the assessment of
macroinvertebrate communities. Each index is developed by assessing a number of criteria for the water
body of interest, as described below.

Index of Biotic Integrity

Used as a measure of the health of fish communities, the IBI consists of 12 criteria, or metrics, designed
to give an overall assessment of the biota. The metrics are developed depending on the type of water
resource being analyzed. The three types of sites include headwaters sites (drainage areas less than
20 square miles), wading sites (drainage areas greater than 20 square miles sampled by wading), and
                                            92

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boat sites (drainage areas greater than 20 square miles sampled from a boat). Each of these types has
its own set of metrics for use in determining the IBI, as shown in Table 6-11.
               Table 6-11.  Index of EJiotic Integrity (IBI) Metrics

                            IBI Metric
Headwaters
   Sites
Wading
 Sites
Boat
Sites
                 1. Total number of'species
                 2. Number of darter species
                   Round-bodied suckers, %
                 3. Number of sunffsh species
                   Number of headwaters species
                 4. Number of sucker species
                   Number of minnow species
                 5. Number of intolerant species
                   Number of sensitive species
                 6. Tolerant species, %
                 7. Omnivores, %
                 8. Insectivorous species, %
                 9. Top carnivores, %
                   Pioneering species,  %
                10. Number of individuals
                11.  Simple lithophils, %
                   Number of simple lithophilic
                   species
                12. Diseased  individuals, %
                   DELT anomalies, %
    X
    X
   X
   X

   X

   X
                            X
                            X
    X
    X
    X
    X

    X
    X

    X
   X
   X
   X
   X

   X
   X
 X
 X
 X
 X

 X
 X
Data for each of these metrics were collected and plotted against drainage area for each of the "least
affected reference sites" in each ecoregion. The plot showing the relationship between the metric and
drainage area was then divided into three equal regions as shown in Figure 6-2. These plots form the
basis for determining the IBI for the water body of concern. When determining the IBI, data for the water
body are compared with the "least affected reference site" plots, and each metric is rated according to
whether it approximates (5), deviates somewhat from (3), or strongly deviates (1) from the value expected
at a reference site. For example, looking at the number of species example shown in Figure 6-2, a water
body with a drainage area of 10 square miles and 10 species collected during a sampling run would be
given a rating of 3 for that metric.  Similar ratings are given for all 12 metrics making up the IBI. After all
ratings for a water body are given, they are added up; the sum represents the water body's IBI. Because
of the rating scales used, the IBI  for a water body  will range from 12 (very poor biotic integrity) to 60
(very good biotic integrity). Ranges of IBI values and their respective qualitative assessments are shown
in Table 6-12.
                                                93

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                  I    I   I  I  I  I  II
                   Wading/headwater sites
                                    10                        100
                                         Drainage Area, mi2
1,000
Figure 6-2.  Number of species vs. drainage area for determining 5, 3, and 1 Index of blotic Integrity (IBI) scoring.
          Table 6-12. Qualitative Assessment of Index of Blotic Integrity (IBI) Values

Wading sites
Boat sites
Headwaters sites
Exceptional
50-60
50-60
50-60
Good
36-48
36-48
40-48
Fair
28-34
26-34
26-38
Poor
18-26
16-24
16-24
Very
Poor
<18
<16
<16
Modified Index of Well Being
The Mtwb is the second index used to describe the quality of fish populations in water bodies throughout
the state. A more traditional index, the Mlwb takes into consideration the fact that healthy systems support
a larger variety and abundance of fish than stressed systems. This index incorporates four measures of
fish community health:
• Numbers of individuals
• Total biomass
• Shannon diversity index based on numbers
• Shannon diversity index based on weight
                                              94

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The formulas used to calculate Mlwb are:
                           Mlwb = 0.5 In N + 0.5 In B + H(no.) + H(wt.)
where:
     N = relative numbers of all species (excluding species designated highly tolerant)
     B = relative weights of all species (excluding species designated highly tolerant)
 H(no.) = Shannon diversity index based on numbers
 H(wt.), = Shannon diversity index based on weight
The Shannon diversity index is defined by the following formula:
                                     H=-E[(n/N)xln(ni/N)]
where:
nj = relative numbers or weight of the  ith species
N = total number or weight of the sample
Ranges of Mlwb values and  their respective qualitative assessments are shown in Table 6-13.
          Table 6-13.  Qualitative Assessment of Modified Index of Well Being (Mlwb) Values

                               Exceptional       Good       Fair       Poor
                                             Very
                                             Poor
          Wading sites
          Boat sites
>9.5
            8.0-9.3
            8.3-9.4
5.9-7.9
6.4-8.7
4.5-5.9
5.0-6.4
<5.0
Invertebrate Community Index
The ICl is used to measure the health of the invertebrate community. Invertebrates are useful as
indicators of environmental quality because they (Ohio EPA, 1987):
• Form permanent and relatively immobile communities
• Can be easily collected in large numbers even in small water bodies
• Can .be sampled at relatively low cost per sample
• React quickly to environmental change
• Occupy all stream habitats
• Inhabit the middle of the aquatic Food web
The method used to determine the ICl is similar to that for the IBI. A number of "least affected reference
sites" were identified and sampled to develop criteria. The ICl consists of 10 invertebrate community
metrics each with four rating categories (0, 2, 4, and 6). The 10 metrics used to calculate the ICl are:
• Total number of taxa
• Total number of mayfly taxa
• Total number of caddisfly taxa
• Total number of dipteran taxa
• Percent mayfly composition
• Percent caddisfly composition
                                              95

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 • Percent tribe tanytarsini midge composition

 • Percent other dipteran and non-insect composition

 • Percent tolerant organisms

 • Total number of qualitative EPT taxa [EPT = Ephemeroptera (mayflies), Plecoptera (stoneflies),
   Trichoptera (caddisflies)]

 The rating involves giving 6 points to sites of exceptional quality, 4 points for those representing typical
 good  communities, 2 points for  slightly affected  communities, and 0 points  for  highly  affected
 communities. As shown in Figure 6-3, plots have been developed to determine the range of values for
 each metric. For example, a stream sample that has a drainage area of 100 square miles and a total of
 30 taxa would receive a rating of 4. A similar analysis is performed for each  metric and the 10 values
 are summed to obtain the final ICI value. This value, which ranges from 0 to  60, represents the health
 of the water body with respect to the invertebrate community. Ranges of ICI values and their respective
 qualitative assessments are shown in Table 6-14.
          60
          50
         40
          30
         20
          10
                                                                    I
                              10
                                                100
                                          Drainage Area, mi2
                                                                  1,000
     10,000
Figure 6-3.  Total taxa vs. drainage area for determining 6, 4, 2, and 0 invertebrate community Index (ICI) scoring.
         Table 6-14.  Qualitative Assessment of Invertebrate Community Index (ICI) Values


                               Exceptional       Good       Fair        Poor
Very
Poor
         All sites
                                 48-60
                                               34-46
                                                          14-32
                                                                     2-12
Example of Biocriteria Implementation

Taken from the upper Hocking River in Ohio, the calculation of IBI values for fish habitat at two different
river headwater stations are shown  in Table 6-15.  In this example, the fish habitat at Station 2 is
significantly better than at Station 1. As indicated by Table 6-12, the index for Station 1 (14) ranks it as
very poor for fish habitat, while the rating for Station 2 (34) ranks it as fair for fish habitat.  In order to
                                               96

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compare these habitats effectively, strict controls had to be kept over the
fish and analyze the results. To implement similar programs in other areas
studies and tests must be conducted because of the site-specific nature of
the IBI.
Table 6-15. Indices of Biotic
Integrity for Two Headwater
methods used to obtain the
, the necessary background
the criteria used to develop
Stations in Hocking River, Ohio
Station 1

Numbers of
Total species
Total individuals
Sunfish species
Sucker species
Intolerant species
Proportion of individuals, %
Round-bodied suckers
Omnivores
Insectivores
Tolerant species
Top carnivores
Simple lithophils
Anomalies
Totals
Value

5
12
1
1
0

0
67
19
(36
7
7
0

Ranking

1
1
1
1
1

1
1
1
1
3
1
1 .
14
Station
Value

14
130
4
3
0

34
38
50
42
10
57
0

2
Ranking

3
1
5
3
1

3
1
3
1
3
5
5
34
References
When an  NTIS number is cited in a reference, that
document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650
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Maughan,  J.T.  1993.  Ecological  assessment  of
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Novotny, Vladimir.  1992. Unit pollutant loads. Water
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Ohio EPA. 1987. Ohio Environmental Protection Agency.
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 Pielou, E.C. 1975. Ecological diversity. New York, NY:
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 Pitt,  Robert. 1989. SLAMM  5—source loading  and
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 U.S.  EPA.  1976b. U.S.  Environmental  Protection
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 U.S. EPA. 1979. U.S. Environmental Protection  Agency.
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  U.S.  EPA.  1983a.  U.S.  Environmental  Protection
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  U.S.  EPA.  1985b.  U.S.  Environmental  Protection
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  U.S.  EPA.   1986   as  updated  in  1987.  U.S.
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U.S. EPA. 1992. U.S. Environmental Protection Agency.
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U.S.  EPA. Undated. U.S.  Environmental Protection
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  managers. Final report.
                                                  99

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                                              Chapter 7
                             Screen Best Management Practices
Selecting BMPs for preventing and controlling urban
runoff  pollution  is  a  two-step  process.  First,  a
comprehensive list of BMPs should be compiled and
screened to eliminate those that are inappropriate for
the area. Based on appropriate BMPs, alternatives are
then developed and assessed. Finally, the BMPs to be
implemented are selected.

This chapter addresses the first step in this process—
initial screening.  First,  a  general overview  of the
categories  of  BMPs addressed in this handbook  is
given.  The  chapter then  describes  methods   of
screening the list of potential BMPs. The remainder  of
the  chapter defines  BMPs used for  urban  runoff
pollution  prevention  and control,  along with  a brief
description  of  their characteristics  and  sources  of
additional information. This chapter's contents assist in
compiling a list  of  BMPs  for  consideration  in the
screening process.

Best Management Practice Overview
Urban  runoff pollution problems are  more difficult  to
control than steady-state,  dry-weather point  source
discharges because of the intermittent nature of rainfall
and runoff, the number of diffuse discharge points, the
large variety of pollutant source types, and the variable
nature of the  source  loadings. Since the  expense  of
constructing facilities to collect and treat urban runoff is
often prohibitive, the emphasis of storm water pollution
control should be on developing a  least cost approach
which  includes nonstructural controls  and low-cost
structural controls.
Nonstructural controls include regulatory controls that
prevent  pollution  problems  by  controlling   land
development and land use. They also include source
controls  that  reduce  pollutant buildup  or lessen  its
availability  for washoff during rainfall. A case study at
the  end  of this chapter  discusses the  extensive
nonstructural regulatory urban runoff controls used  by
Austin, Texas.
Low-cost structural controls include the use of facilities
that encourage uptake  of  pollutants by vegetation,
settling,  or filtering.  Because  of the variability  of
pollutant removal,  these  controls can  be  used  in
series  or in  parallel  combinations.  The  concept of
implementing a "treatment train"  might, for example,
include initial pretreatment, primary pollutant removal,
and final effluent polishing practices to be  constructed
in series.
All sources, both point and nonpoint, in a program area
or watershed should be addressed. For urban areas,
such sources often include urban runoff  as well as
CSOs. Practices for controlling both  storm water and
CSO  pollution are described  in this  chapter.  The
practices discussed for urban runoff  control are  also
applicable to storm water before it enters  a combined
sewer  collection  system.  In  addition, this chapter
describes various  types  of storage and  treatment
facilities also commonly used to address CSOs.

Depending on the pollutant control mechanisms used,
urban  runoff pollution  control practices can be divided
into several categories:
• Regulatory controls

• Source controls

• Detention facilities

• Infiltration facilities

• Vegetative practices

• Filtration practices
• Water quality inlets
CSO-specific  control  practices are also  divided into
several categories:

• Source controls

• Collection system controls

• Storage

• Physical treatment

• Chemical precipitation

• Disinfection
While  these  lists do not include  all  urban runoff and
CSO control practices, these categories are convenient
ones for purposes of presentation and discussion.
                                                   101

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 Table 7-1 lists commonly used urban  runoff and CSO
 BMPs based on the categories  provided.  The  next
 section describes methods  of  BMP  screening.  The
 remainder of the chapter then gives a brief overview of
 some of the  more  important characteristics of these
 BMPs, including the types of pollutants controlled, the
 pollution removal mechanisms employed, limitations on
 their  use,  maintenance  requirements,  and  general
 design considerations.

 Best Management Practice Screening

 The goal  of  BMP  screening  is   to  reduce   the
 comprehensive list of BMPs to a more manageable list
 for  final selection.  Because this step  is  an  initial
 screening, methods used are generally qualitative and
 require   professional   judgment.  While   extensive
 knowledge  about  specific  design   criteria  is   not
 necessary at this stage in  the  screening  process,


 Table 7-1. Urban Runoff Pollution Control BMPs

 Urban Runoff Controls

 Regulatory Controls
 Land uso regulations
 Comprehensive runoff control regulations
 Land acquisition
 Source Controls
 Cross-connection Identification and removal
 Proper construction activities
 Street sweeping
 Catch basin cleaning
 Industrial/commercial runoff control
 Solid waste management
 Animal waste removal
 Toxic and hazardous pollution prevention
 Reduced fertilizer, pesticide, and herbicide use
 Reduced roadway sanding and salting
 Detention Facilities
 Extended detention dry ponds
 Wet ponds
 Constructed wetlands
 Infiltration Facilities
 Infiltration basins
 Infiltration trenches/dry wells
 Porous pavement
Vogctatlva Practices
Grassed swales
Filter strips
Filtration Practices
Filtration basins
Sand fillers
Other
Water quality inlets
 understanding the BMP's effectiveness and applicability
 to the program area's problems is crucial.
 For this  discussion, the  BMPs are divided into two
 general  categories:   nonstructural   and  structural.
 Nonstructural    BMPs—which    include    regulatory
 practices, such as those  that limit impervious area or
 protect natural resources, and source controls, such as
 street  sweeping or  solid  waste management—are
 typically implemented throughout an entire community,
 watershed, or special area. While structural BMPs, such
 as detention ponds or infiltration practices, may be
 designed to address specific pollutants  from  known
 sources, they also can be implemented throughout an
 area.  In addition, structural BMPs can be required in
 new developments or redevelopments.
 Comprehensive plans addressing urban runoff pollution
 prevention  and control rely  on both nonstructural and
 structural practices.  While  plans addressing specific
CSO Controls

Source Controls
Water conservation programs
Pretreatment programs

Collection System Controls
Sewer separation
Infiltration control
Inflow control
Regulator and system maintenance
Insystem modifications
Sewer flushing

Storage
Inline storage
Offline storage
Flow balance method

Physical Treatment
Bar racks and screens
Swirl concentrators/vortex solids separators
Dissolved air flotation
Fine screens and microstrainers
Filtration

Chemical Precipitation

Biological Treatment

Disinfection
Chlorine treatment
UV radiation
                                                     102

-------
problems in small watersheds might tend to focus on
structural practices, urban  runoff pollution prevention
and control programs should include implementation of
nonstructural as well as structural control approaches.
Methods for screening both nonstructural and structural
practices are outlined below.

Nonstructural Practices

Since the number of potential nonstructural BMPs to be
implemented is very large, initial screening is useful
before the  final selection process. The regulatory and
source control BMP descriptions contained later in this
chapter focus  on the  most commonly  implemented
practices;  other,  less  commonly  used   practices,
however, also could be considered. In addition, each
practice (e.gi, solid waste management) can be divided
into numerous subpractices (e.g., management of leaf
litter,  rubbish, garbage, and lawn clippings). An urban
runoff management plan for the Santa Clara Valley, for
example, identified more than  100 separate potential
nonstructural  BMPs   used throughout  the  country
(Woodward-Clyde Consultants,  1989).  Municipalities,
therefore, have to screen regulatory and source control
BMPs based on their particular watershed. The Santa
Clara  Valley program  and the BMP  screening and
selection method are discussed in the case study at the
end of Chapter 8.
One  screening method involves  applying  screening
criteria to each nonstructural practice to determine its
applicability to the conditions  in the watershed. The
screening criteria, which are specific to the watershed
and depend on the program goals, include:
• Pollutant removal: Since different regulations and
   source control practices are designed to  address
   different pollutants, the program team should ensure
   that the screened list of controls includes practices
   designed  to address   the  pollutants of  primary
   concern. In  addition,  some  practices  might  not
   provide sufficient pollutant removal.
• Existing  government  structure: Some   practices
   implemented throughout  the  country   require  a
   specific  government structure. For example, while a
   strong county government might be important for
   implementing a specific regulatory control, the role of
   county governments can vary from one section of the
   country   to  another.  Practices  requiring  specific
   government structures that do not exist in the area
   of concern therefore could be eliminated from the list.

 • Legal  authority:  For   regulatory  controls  to  be
   effective, the legal authority to implement and enforce
   the regulations must exist, if municipal boards and
   officials  lack this authority, they could be required to
   obtain it through local action.
• Public or municipal acceptance: Implementing certain
  practices could be difficult because of resistance from
  the public or an involved municipal agency. These
  practices can be eliminated from the list.

• Technical feasibility: The municipal BMPs that require
  large expenditures and extensive efforts might not be
  suitable for small municipalities that lack the required
  resources.
Additional screening  criteria may also be used, as
shown in the Santa Clara Valley case study at the end
of Chapter 8.
Another  method of screening  involves  use  of  a
comparative  summary  matrix.  Figure 7-1 shows an
example of such a  matrix that can be used to screen
nonstructural control practices. Though  developed for
screening nonstructural control practices in coastal
areas, this matrix is at least in part applicable to inland
areas  as well. In this matrix, various regulatory and
source control practices are listed and their abilities to
meet various criteria are compared.  The criteria listed
include ability to remove specific pollutants, such as
nutrients  and sediments, maintenance requirements,
longevity, community acceptance, secondary environmental
impacts, costs, and site requirements. Other criteria are
also listed, some of which are applicable only in coastal
areas. For each practice and criterion, an assessment
of effectiveness is indicated: solid circles indicate high
effectiveness and open circles, low effectiveness. This
type  of matrix can provide a basis  for an  initial
assessment of practices and their applicability to the
program.

 Structural Practices
 Because structural practices generally are more site
specific  and have more restrictions  on  their use than
 nonstructural  practices, the initial screening step for
these  practices  can  be  more  precise  than for
 nonstructural practices. Table 7-2 outlines some of the
 more  important criteria for  the screening of structural
 BMPs,  including   their   typical  pollutant   removal
 efficiencies, land requirements,  the drainage area that
 each  BMP  can  effectively  treat,  the  desired  soil
 conditions, and the desired ground-water elevation.  By
 using these criteria and the  information obtained during
 data collection and analysis and problem identification
 and ranking, the program team can  narrow the list of
 BMPs to be further assessed in the BMP selection step.
 The   initial  screening  criteria  for  structural  control
 practices include the following:
 • Pollutant removal: The municipality  should ensure
   that BMPs selected address the primary pollutants of
   concern to the level of removal desired.
                                                   103

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 Table 7-2. Structural BMP Initial Screening Criteria
Structural BMPs
Detention Facilities
Extended detention
dry ponds
Wat ponds

Constructed wetlands

Infiltration Facilities
Infiltration basins

Infiltration
trenches/dry wells
Porous pavement

Vegetative Practices
Grassed swales

FHtor strips

Filtration Practices
Filtration basins

Sand filters

Other
Water quality Inlets


Suspended
Solids

Medium

Medium-
high
Medium-
high

Medium-
high
Medium-
high
High


Medium

Medium-
t^t «
high

Medium-
high
High


Low-
medium
Typical
Nitrogen
•
Low-
medium
Medium

Low


Medium-
high
Medium-
high
High


Low-
medium
Medium-
high

Low

Low-
medium

Low

Pollutant Removals3
Phosphorus

Low-medium

Medium

Low-medium


Medium-high

Low-medium
Medium


Low-medium

Medium-high


Medium-high

Low


Low

Pathogens

Low

Low

Low


High

High
High


Low

Low


Low

Low


Low

Metals

Low-
medium
Medium-
high
Medium-
high

Medium-
high
Medium-
high
High


Low-
medium
Medium


Medium-
high
Medium-
high

Low

Relative
Land
Require-
ments

Large

Large

Large


Large

Small
N/A


Small

Varies


Large

Varies


N/A

Drainage
Area"

Medium-
large
Medium-
large
Large


Small-
medium
Small
Small-
medium

Small

Small


Medium-
large
Low-
medium

Small

Desired
Soil
Conditions

Permeable

Impermeable

Impermeable


Permeable

Permeable
Permeable


Permeable

Depends
on type

Permeable

Depends
on type

N/A

Ground-
Water
Elevation

Below
facility
Near
surface
Near
surface

Below
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Below
facility
Below
facility

Below
facility
Depends
on type

Below
facility
Depends
on type

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.  tawn — -*ww/Qt iviouiuui — wwu/o, i iiyu = t»
  Small» <10 acres, Medium = 10-40 acres, Large = >40 acres.

• Land requirements:  Large land  requirements for
  some of the aboveground structural BMPs can often
  restrict  their  use in highly developed  urban areas.
  Land requirements vary depending on the BMP.
* Drainage area: The structural BMPs listed in Table
  7-2 are  used  primarily to treat runoff from watersheds
  up to 50 or 60 acres, and the optimum drainage area
  to be served varies for each practice and according
  to the  land  use (connected  impervious area, for
  example). Drainage areas above this size might have
  to be treated by locating BMPs in subwatersheds.
• Soil characteristics: Structural BMPs  have differing
  requirements for soil  conditions. Infiltration facilities
  generally require permeable soils, while detention
  BMPs  generally require  impermeable soils.  The
  municipality must become familiar with soil conditions
  in the watershed.
•  Ground-water elevation: The ground-water elevation
   in the watershed can be a limiting factor in siting and
   implementing  structural  BMPs.  Generally,   high
   ground-water elevation can restrict  the  use  of
   infiltration facilities  and filtration practices; but it is
   necessary for  constructed  wetlands and may be
   desirable for detention facilities.
•  Public acceptance: Since a municipality could have
   difficulty implementing a  structural  BMP  without
   public  approval, public acceptance of the  BMPs
   should be considered in the screening step.

Of the screening criteria listed, the pollutant removal,
land  requirements, and  drainage  area  served are
usually   absolute  restrictions.  Soil   condition   and
ground-water elevation,  on the other hand,  impose
restrictions that could  be overcome by such means as
importing soil or constructing facilities with clay liners to
                                                  106

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restrict  ground-water  inflow.  Such  modifications,
however, can add significantly to the BMP costs.

Best Management Practice Descriptions

This section  provides a brief overview of the BMPs
discussed, based on the categories presented in Table
7-1. Additional references  should be consulted before
selecting,  designing,  and implementing  BMPs  (see
Appendix A). Appendix B lists widely available and
helpful  documents   that   provide   more   detailed
information on designing, constructing, and maintaining
urban runoff and CSO BMPs. There are a host of other
BMPs that address specific pollution sources, such as
landfills, industrial sites, salt storage facilities, marinas,
and numerous others. As mentioned earlier, agricultural
BMPs are not discussed in depth in this handbook.

Urban Runoff Control Practices

This section addresses  regulatory  controls,  source
controls, and several types of commonly used structural
controls.

Regulatory Controls

Urbanization increases the amount of impervious land
area, which in turn increases storm water runoff with its
associated pollutants (see Chapter 1).  Municipalities
can prevent or reduce many of these pollution problems
by implementing regulatory controls to limit the amount
of impervious area and to protect valuable resources.
These regulatory controls can prevent or limit the
quantity of runoff as well as its pollution load. Regulatory
controls typically implemented by municipalities include:

•  Land use regulations, such as:
   - zoning ordinances,
   - subdivision regulations,
   - site plan review procedures, and
   — natural resource protection.
•  Comprehensive runoff control regulations.

•  Land acquisition.
Local government regulations can require storm runoff
controls, reduce the level of impervious  area, require
the preservation of natural features,  reduce erosion, or
require other important practices. The  major aspects of
storm  water prevention and control—including runoff
quantity  control, solids control,  and other  pollution
control—are illustrated in the case study  at the end of
this chapter on the regulatory practices implemented by
Austin, Texas.
Runoff  Quantity  Control.  Regulations addressing
runoff  quantity  control can be used to reduce the
effects of land  development on watershed hydrology.
Hydrologic control  in turn results in pollution contra/,
and can be accomplished through requirements such as:

• Open space: By maintaining specified levels of open
  space  on a development site, the total  area  of
  impervious surface is reduced and  infiltration  of
  precipitation is increased. This leads to decreases in
  total pollutant  discharge  and potential  downstream
  erosion by reducing total  and peak runoff flows.

• Postdevelopment flow control: Many development
  regulations require that peak runoff  conditions from
  a site  be  calculated before and after construction.
  These  requirements  specify that conditions  after
  construction   must    reflect   conditions   before
  construction. This  control is typically accomplished
  through the use of detention facilities, which can
  reduce peak  runoff discharge   rates,   thereby
  decreasing  downstream  erosion  problems. These
  regulations  specify   the  desired  outcome;  the
  approach  for  ensuring that  outcome,  however, is
  determined by the  developer.

• Runoff recharge: Regulations may specify that storm
  water runoff be recharged on site. Such regulations
  can reduce the runoff leaving a site, thereby reducing
  development-induced   hydrologic   changes  and
  pollutant transport. By directly promoting infiltration,
  peak and total runoff rates can be decreased and
  pollutant discharges and downstream erosion can be
  reduced.  Such  runoff  recharge  also  might  help
  maintain surficial aquifer  levels.
Solids Control. Regulations addressing solids control
could include requirements for control  practices during
and after construction,  since  such  activity has  been
shown to be a major contributor of solids. Construction
activities can greatly increase the level of suspended
solids in storm  water runoff by  removing vegetation
and  exposing the  topsoil  to  erosion   during  wet
weather. Yet while communities have requirements for
implementing erosion control practices on construction
sites, fewer communities require erosion control after
construction is complete. Since many other land uses
can contribute solids loadings, regulatory requirements
can cover various types of industrial  and commercial
activities.

Other Pollution Control. Land development  increases
the  concentrations of  nutrients, pathogens,  oxygen
demanding  substances, toxic contaminants,  and salt
in  storm  water  runoff.  Development   regulations,
therefore, can be used to address  some  of these
specific pollutants. These regulations can take the form
of special requirements for limiting nutrient export in
special  protection  districts  or setting  performance
standards for known problem pollutants.
While many of the regulatory controls outlined in this
section are used by municipalities, few  communities
                                                   107

-------
 have used these regulations systematically to prevent
 urban runoff pollution problems. The regulations, developed
 over a number of years,  have had  purposes largely
 unrelated  to urban  runoff pollution  prevention  and
 control. By reexamining and amending these regulations
 and ordinances to reflect water resource goals, however,
 communities can improve their ability to prevent and
 control urban runoff pollution.

 Land Use  Regulations.  Land  use  regulations  can
 include zoning ordinances, subdivision and site plan
 regulations and review requirements, and environmental
 resource   regulations  such  as  wetlands  protection.
 These  practices   are   used   as  tools  to promote
 development patterns that are compatible with control
 of urban runoff discharges.

 Zoning, Most communities have residential, commercial,
 industrial,  and other zoning districts that specify the
 types of development allowed and dictate requirements,
 including:

 • Specifying the  density  and type  of development
  allowed in  a given area, thereby maintaining pervious
  areas.

 • Controlling acreage  requirements  for  certain  land
  uses  and associated  setback,  buffer,  and  lot
  coverage requirements.

 • Directly and indirectly affecting the types of materials
  that can be stored or used on sites.

 • Not  allowing  potentially  damaging  uses  (e.g.,
  underground chemical storage or pesticide application)
  in sensitive watersheds.

 Examples of  types of zoning controls that can be used
 to protect water bodies include:

 • C/asfercfeve/opme/tf: Allowing structures in developments
  to be constructed close  together to preserve open
  space.

 • Down-zoning: Changing an established zone to a use
  that allows a lower level  of density.

 * Phase-in zoning: Changing the zoning of a specific
  area over time, usually as inappropriate sites reach
  the end of  their useful life.

 • Large lot zoning: Requiring greater minimum acreage
  for development in certain locations.

• Conditional zoning: Allowing certain  activities  only
  under specified conditions that protect water quality.

• Overlay zoning: Placing additional zoning requirements
  on an area  that is already zoned for a specific activity
  or use.

• Open space preservation: Protecting open space and
  buffer zones in the community near water bodies.
 • Performance standards: Permitting certain land uses,
   usually industrial activities, only if they meet specific
   performance criteria.

 These practices can be used by communities to ensure
 that land uses  in each area are appropriate for that
 area's water resources.  Such controls are especially
 useful  in  sensitive  areas,   such  as water  supply
 watersheds,  and  can  serve to reduce  or control
 development.

 Subdivision Regulations. Subdivision review deals with
 land that is divided into separately owned parcels for
 residential  development.   Municipalities  have  the
 authority to review the plans for such subdivisions and
 to restrict development options  via requirements for
 drainage, grading,  and  erosion  control, as  well as
 provisions  for   buffer  areas,   open  spaces,  and
 maintenance. Through this  review, municipalities can
 ensure that  proper practices  are designed into  the
 development.

 Site Plan Review. Site plan review ensures compliance
 with  zoning,   environmental,  health,  and  safety
 requirements. Municipalities can require developers to
 consider how construction activities will affect drainage
 on site and to design plans for reducing urban  runoff
 pollution problems.  Developers usually are required to
 submit  information  to a  municipality  on the natural
 drainage characteristics of the site, plans for erosion
 control, retention and protection of wetlands and water
 resources, arid disposal of construction-related wastes.

 Natural Resource Protection. Municipalities can also
 protect water resources by  protecting  lands, such as
 floodplains, wetlands, stream buffers, steep slopes, and
 wellhead areas.  By use of resource overlay zones that
 restrict  high  pollution  activities  in   these  areas,
 development can be controlled and the potential for
 urban runoff pollution can be reduced.

 Comprehensive Runoff  Control Regulations.  In
 addition to strengthening and broadening existing local
 regulatory control practices, states and municipalities
 can   implement  runoff   pollution   control  through
 comprehensive regulations.  While still relatively rare,
 comprehensive plans to address urban runoff pollution
 exist  in various  states and communities. They are
 designed  to  fully  address   urban  runoff  pollution
 problems  by identifying specific  land  use  categories
and  water resources that deserve special  attention,
and outlining methods for implementing source control
and  structural   BMPs.  While  the  form  that these
comprehensive regulations take is very specific to the
needs   of  a  state  or  community,   reviewing  the
regulatory approaches that have been tried by others is
useful in developing options.  Examples include (Pitt,
1989):
                                                  108

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• Austin, TX: Comprehensive Watersheds Ordinance,
  1986; Urban Watersheds Ordinance, 1991  (see the
  case study at the end of this chapter).

• Birmingham,  AL: Proposed Watershed  Protection
  Ordinance.

• State of Maryland: Model Stormwater  Management
  Ordinance, 1988.

• State of Wisconsin: Model Construction Site Erosion
  Control Ordinance, 1987.
Land Acquisition. To protect valuable resources from
the effects of development, municipalities  can  purchase
land within the watershed to control land  development.
Municipalities can acquire land to convert to parks or to
maintain as  open space; this  approach,  however, can
be very expensive.

Source Control Practices
Source controls  include  the nonstructural  practices
designed to  reduce the availability of pollutants. Many
of these practices tie directly into EPA's  Pollution
Prevention  strategy discussed  in  Chapter  2, which
focuses on preventing pollution  sources  from entering
the system rather than on treatment. Some of the more
common practices used by municipalities  throughout
the country include:
• Cross-connection identification and removal
• Proper construction activities
• Street sweeping and catch basin cleaning

•' Industrial/commercial runoff control
• Solid waste  management
• Animal waste removal
• Toxic and hazardous waste management

• Reduced fertilizer, pesticide, and herbicide use
• Reduced roadway sanding and salting

Cross-Connection  Identification  and   Removal.
Within the NPDES storm water regulations,  EPA has
specifically emphasized the importance of implementing
a program to identify and  remove inappropriate sanitary
and industrial wastewater connections to municipal storm
water  drainage systems—a  problem  in many  urban
areas. For  example, a study of  the  storm drainage
system in  the Humber River  watershed  in Toronto
indicated that about 10  percent of the outfalls from
the system  had  dry-weather flows considered to  be
significant  pollutant sources.  This study  found that
more than  50 percent of  the  annual discharges of
water volume, total suspended solids, chlorides, and
bacteria from the monitored industrial, residential and
commercial  areas were  associated with dry-weather
discharges from the storm drainage system (U.S. EPA,
1993a).                  .
Dry-weather discharges, such as from illegal wastewater
discharges to the storm drainage system, can cause
serious water  resource  degradation. The addition of
sanitary  wastes  increases  the  concentrations  of
organics, solids, nutrients, and bacteria in the  storm
water runoff. Industrial wastes can be highly variable but
can substantially increase the concentrations of heavy
metals and other related pollutants in runoff (U.S. EPA,
1993a).

Unauthorized and inappropriate connections to drainage
systems can exist for  many reasons. In the past,
connector pipes between  sanitary sewers and  storm
drains  could have been installed to relieve surcharging
of the  sewer system and prevent backups of sewage
into homes and businesses. Connections from residential
sanitary  sewers or  commercial  and  industrial  floor
drains  also exist.                            '

Cross-connections are common  in municipalities that
have undergone sewer separation. During separation,
a  new pipe system  is often constructed to act as a
separate sanitary sewer, and the old combined system
is converted to operate as a separate storm drain
because of  its large size and carrying capacity.  To
complete the separation,  existing  connections to the
combined sewer must be plugged and  reconnected to
the new sanitary sewer. If sewer connections to the
newly  created storm drain  continue to exist with  no
written record or are  not located on plans, they can be
missed during the reconnection.  In addition, as new
construction occurs,  accidental  connections to  the
storm drainage system can occur.
Because cross-connections typically are not documented,
pollution from these connections can often be difficult to
locate. Municipalities, however, can develop a program
to locate and eliminate these connections. This program
should be designed to identify dry-weather discharges
and to  determine the  flow sources  by developing
updated drainage  system  maps,  conducting dry-
weather  inspections,  and  sampling  dry-weather
discharges.  In some instances, discharge results from
ground-water infiltration to the drainage system  and
might  not be  a  pollution  concern. If the analyses
conducted on dry-weather flows indicate the presence
of pollutants, however, the system should be traced to
locate the source of the pollutants.
Locating cross-connections to storm drainage systems
is similar to conducting the infiltration and inflow (I/I) and
sanitary sewer evaluation survey (SSES) investigations
that many  municipalities  regularly  conduct. These
investigations can be done  through successive visual
inspections, dye  testing,  or TV investigations. Once
located, cross-connections must  be  removed so  that
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 Industrial and sanitary wastes are discharged  to  a
 municipal sewerage system. Routine drainage system
 inspections should continue in order to avoid problems
 from inadvertent cross-connections from new development.

 Detailed information is available in  an EPA guidance
 document entitled Investigation of Inappropriate Pollution
 Entries  Into  Storm Drainage Systems  (U.S.  EPA,
 1993a).

 Proper Construction Activities. Construction activities
 have been cited in numerous water quality assessments
 as a  major source of sediment to surface  waters.
 During construction, natural  vegetation  is removed
 from a site, exposing the topsoil. If the soil remains
 bare and exposed for  extended periods, rainfall can
 cause erosion and transport the soil to nearby water
 bodies. After the soil enters a water body, decreases in
 water velocity cause the suspended solids to settle out
 of the water column and accumulate as sediment on
 the  bottom of  the  water body. This  sediment can
 smother benthic organisms and carry pollutants,  such
 as  petroleum  products  and  metals.  Construction-
 induced  erosion therefore should  be minimized. This
 section addresses some of the planning practices and
 controls  that  can be used at construction sites  to
 reduce erosion and subsequent soil transport.

 While the practices discussed in this section are general
 and can  be applied at construction sites throughout the
 country,   most  state  environmental   offices   have
 developed soil and erosion control handbooks tailored
 to the specific needs of the state. These documents
 provide  more detailed  guidance for developing and
 implementing  programs to address construction site
 pollution problems.  In addition, some  municipalities,
 such as Birmingham,  Alabama  (Pitt,  1989),   have
 developed  ordinances  to  address construction-site
 erosion controls.

 On construction sites, areas to be maintained in  their
 preconstruction  condition  should remain  undisturbed
 during   construction;   existing  vegetation   to  be
 incorporated into the final site should  be maintained.
 The planned roads and parking areas should be used
 for construction traffic and other construction-related
 activities; these areas can be treated with crushed stone
 during construction and paved after construction has
 been completed. Planned open areas at a site should
 be seeded immediately after clearing, and open areas
 not in use  for  construction should  be covered  with
 crushed stone or seeded with a temporary cover crop.

The planning, sequencing, and timing  of construction
activities are also important to reduce  soil  transport.
 Phasing  and limiting of clearing activities so that one
area  of  a  site is  complete  and  stabilized  before
beginning work on other  areas can also reduce the
potential  for erosion.
 On large construction sites with extensive grading and
 vegetation removal, structural erosion control practices
 are required. During construction activities, temporary
 berms or weirs can  divert runoff away from disturbed
 areas of the site. Runoff diversion or slope modifications
 should be incorporated into the final site design; during
 construction, these  diversion  structures should  be
 protected by  crushed stone  or blankets to reduce
 erosion.

 Since construction site runoff contains  high  levels of
 suspended solids, temporary structures that filter out or
 settle out solids should be incorporated into the site.
 Straw  bales,  silt fences,  dewatering  filters,  and
 sedimentation basins are often used to control erosion.
 Straw bales can be placed across  a sloped area to
 intercept runoff from the slope and trap sediment. They
 can also be used around  storm water inlets and catch
 basins to reduce the transport of sediment to nearby
 drainage systems. In addition, straw bales  can be
 placed at intervals along  long slopes to reduce runoff
 velocity  to control erosion. Straw bales  need to be
 replaced every few months; the old bales can be broken
 up and  used for ground cover if properly installed and
 maintained. Silt fences can be used for many of the
 same functions as straw bales  and usually  have a
 longer life.

 In addition to these temporary, inexpensive erosion-
 control   devices,  storm  water  runoff  from  larger
 construction sites should be directed to  sedimentation
 basins,  designed to intercept runoff and hold it for an
 extended period to allow suspended solids to settle out.
 Sedimentation basins, which require periodic cleaning,
 already might be incorporated into the final site design
 as permanent  storm  water  attenuation/treatment
 controls. When construction is completed, they should'
 be cleaned out and the bottoms regraded.

 To ensure  that  construction  site   erosion  control
 practices are properly implemented and that regulations
 are  followed,  plans  must be  reviewed   prior to
 construction  activities  and  inspections  must  be
 conducted. Municipalities or responsible agencies must
 provide for erosion control plan review, site review, and
 enforcement.

 Street   Sweeping  and   Catch  Basin  Cleaning.
 Frequent street sweeping can limit the accumulation of
 dirt,   debris,  and  associated   pollutants,  and  the
subsequent deposition of these pollutants  in storm
drains and  waterways.   Regular  cleaning  of catch
basins can  also remove  accumulated sediment and
debris that ultimately could be discharged from storm
drains and combined sewers. In most municipalities,
these tasks are conducted at scheduled intervals and
have  been  shown to result  in  significant  pollutant
reductions only if an  intensive schedule  is followed. A
study  performed in San Jose, California, showed that
                                                  110

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50 percent of the total solids and heavy metals could
be removed from urban  runoff when city streets were
cleaned once or twice a day. When the streets were
cleaned only once or twice a month, the removal rate
dropped  to  less  than 5 percent (U.S.  EPA,  1979).
Increased frequency also  could  result  in  increased
fugitive  air emissions.  Regular street sweeping and
catch basin Cleaning can, in any case, remove some of
the large floatable  litter that is unsightly  in  urban
surface  waters.  Street sweeping twice  a week and
catch basin  cleaning once or twice a year have been
found effective  in  removing  these  large  floatable
pollutants (U.S. EPA,  1983). Determining the effectiveness
of street  sweeping  programs,  however,  is difficult
because of  variations in pollutant buildup and  storm
events. In addition, studies have shown that the choice
of sweeping equipment can  significantly affect  the
effectiveness of cleaning programs (Pitt, 1989).

Commercial/Industrial   Runoff  Control.   Certain
commercial and industrial sites can be responsible for
disproportionate contributions of some pollutants (e.g.,
grit, oils, grease,  and toxic materials) to the drainage
system. Typical sources of potential concern include
gasoline stations, railroad yards, freight loading areas,
and parking lots. In specific cases where significant
pollutant loadings to the  system are contributed by
well-defined locations of limited area, pretreatment of
the runoff from  these areas could be a  practical and
effective control measure. Pretreatment measures can
be  required as part  of a  community's regulations.
Examples of pretreatment measures include oil/water
separators for gasoline stations, or the use of modified
catch basin designs  to enhance the retention  of oil and
grease or solids. Procedures for the detection and
location of illicit connections to separate storm drains
by testing for specific chemical tracers could be applied
to identify commercial or industrial sources contributing
substantial levels of problem pollutants.

Solid Waste Management. Most communities have
programs to collect  and dispose of solid waste in an
effort to maintain clean  streets and provide a service
for local residents and businesses. Some communities
provide added services during times otparticularly high
waste generation. For example, some municipalities in
the northern United States provide extra collection
services  during the fall to collect leaves—an added
service  that helps  keep  leaves from  blowing into
surface  waters. A study  of storm  water  runoff into
Minneapolis lakes found that phosphorus levels were
reduced by 30 to 40 percent when street gutters were
kept free of leaves and  lawn clippings (MPCA, 1989).
Actual  reductions of  pollutant loads,  however,  are
difficult to predict. In general, any solid  waste that is
picked up and disposed of in a controlled manner will
be less likely to  enter a drainage system.
Animal  Waste  Removal.  Domesticated  and  wild
animal wastes represent a source of bacteria and other
pollutants that can be washed into surface waters by
urban  runoff.  These  pollutants can be  reduced by
reducing  the animal   waste  on  paved  surfaces.
Municipalities often enact and enforce leash laws and
pet waste cleanup  ordinances. The effectiveness  of
these programs in reducing pollutant loads is unknown,
however, and usually depends on voluntary actions by
private citizens.

Toxic and Hazardous Waste Management. Improper
dumping  of  household  and  automotive toxic  and
hazardous wastes into  municipal storm inlets,  catch
basins,  and  other storm drainage  system entry points
can  result in  significant discharges of pollutants  to
surface waters during rainstorms. This dumping can be
a particular problem in urban areas where individuals
change the oil or antifreeze in their cars and dispose of
the  wastes  in  nearby  catch  basins.  In  addition,
homeowners and small businesses sometimes dispose
of products such as waste paints and solvents  in storm
water inlets and catch basins. To address the problem,
municipalities   can   educate   residents  on  the
consequences of dumping these  wastes into storm
drainage system entry points. In addition, communities
can  develop hazardous- and  toxic-waste collection
days to dispose of  or recycle these wastes properly.
Also, storm  drain  systems can  be  labeled  with
warnings about the pollution prcolems associated with
dumping wastes. The effectiveness of such programs,
however, cannot be determined in advance because of
the voluntary nature of compliance. For business and
industry,  an  inspection,  testing,  and enforcement
program (similar to an industrial pretreatment program)
can be developed.

Reduced Fertilizer, Pesticide, and Herbicide Use.
Fertilizers, pesticides, and herbicides washed off the
ground during storms can contribute to water pollution.
Agricultural,  park land,  and other land  uses  can be
sources of these pollutants.  Many communities use
these  chemicals on  park  lands, and  homeowners
utilize them on their lawns. Controlling the use  of these
chemicals on municipal lands and educating the public
can   help  reduce   nutrient   and   toxic  pollutant
concentrations in urban runoff.

Reduced Roadway Sanding and Salting. In  areas of
the United States with freezing road conditions, sand
and  salt are used  in  the  winter to  improve driving
conditions. Salt and sand can be washed off roadways,
however, and pollute receiving waters. The problem is
exacerbated during spring snowmelt and early spring
rainstorms when most of these pollutants are available
for  transport.  These  problems can be  reduced by
minimizing the use  of  chemicals  for snow  and ice
control to the minimum necessary for public safety and
                                                  111

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by utilizing proper equipment. In addition, salt storage
sites have been shown to be persistent and frequent
sources of contamination, especially  during  rainfall
(U.S. EPA, 1973); sand and salt piles therefore should
be covered. Also, deicing alternatives, such as calcium
magnesium acetate  (CMA), can be  used  in  some
cases (U.S. EPA, 1974a,b).

Detention Facilities

One  of the  most common  structural methods  for
controlling urban runoff and reducing pollution loading
is through the construction of  ponds or wetlands to
collect runoff, detain it, and release it to receiving waters
in a controlled manner. Pollution reduction during the
perfod of temporary runoff storage results primarily from
settling of solids. Detention facilities, therefore, are most
effective at  reducing  the concentrations of solids and
the pollutants that typically adhere to solids, and less
effective at removing  dissolved pollutants.
Currently,  the  three types  of  detention  facilities
commonly used to remove pollutants from storm water
runoff are extended detention dry ponds, wet ponds,
and constructed wetlands; each is discussed below. For
more detailed design  information, the references listed
in Appendix B should be consulted.
Extended Detention Dry Ponds. Most municipalities
are familiar with the concept of constructing dry ponds
to  control peak  runoff. When used as water quality
BMPs, dry ponds are designed with orifices or other
structures that restrict the  velocity and volume of the
discharges (see Figure 7-2). Dry ponds thereby detain
the runoff before discharging it to surface waters.
Pollutant Removal. During the storage period, heavier
particles settle out of the runoff, removing suspended
solids and pollutants, such as metals, that attach to the
particles or precipitate out. Some dry ponds also include
vegetated  areas that can  provide pollutant  removal
through filtering and vegetative uptake. Dry ponds are,
therefore, most effective at removing suspended solids
and some  nutrients and  metals, and  less effective at
removing dissolved pollutants and  microorganisms.
Overall,  the pollutant removal  effectiveness of  dry
ponds  has been shown to be less than for wet ponds
and constructed wetlands (see Table 7-2).  ,

Design Considerations. Retrofitting existing dry ponds
with new outlet structures can  sometimes enhance a
municipal flood-control structure to increase its pollution
control effectiveness. Care must be taken, however, to
ensure  that the  overflow  capacity  of the  pond is
maintained, so that it continues to fulfill its original
flood-control  function.   Study  of   the   hydraulic
characteristics of the dry pond will be necessary before
retrofitting. Temporary storage also can be provided for
runoff from smaller storms by  building a small  berm
around an existing outlet  structure.
For water quality dry  ponds, important design criteria
include the desired detention time and the volume of
runoff to be detained.  These factors dictate the pond's
size and affect the pollutant removal  efficiency of the
structures.   Most  dry-pond  sizing  criteria  specify a
             Maximum
             elevation
             of extended
             detention pool
               Safety
               bench
                                                                             Emergency spillway
                                                                                   r\
                          Maintenance access
                          to micropool
FIgur* 7-2.  Extended detention pond (U.S. EPA, 1991 a).
                                                   112

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certain detention time for a given design storm. For
example, the  Maryland  Water Resources Authority
specifies that water quality dry ponds must be large
enough to accommodate the runoff volume generated
by the 1-year, 24-hour storm  to be  released over a
minimum of 24 hours (Schueler, 1987). In contrast, the
Washington State Department of  Ecology (WA  DOE)
specifies that  dry  ponds must be large enough  to
accommodate  the  runoff volume  generated by the
2-year, 24-hour storm and release it over a period of 40
hours (WA DOE, 1991).

Dry ponds should also include some form of low-flow
channel designed to reduce erosion; vegetation on the
bottom of the pond to promote filtering, sedimentation,
and  uptake of  pollutants; and an  outlet  structure
designed to remove pollutants and withstand clogging.
In addition, dry pond designs typically include upstream
structures to  remove coarse sediments  and reduce
sedimentation and clogging of the outlet. Also, outlets
might be connected to grassed swales (biofilters)  to
provide additional pollutant removal (WA DOE, 1991).
Each of these components of a dry pond design either
enhances pollutant removal or reduces operation and
maintenance costs for the structure.

Maintenance  Requirements.  Maintenance of  water
quality  dry  ponds  is important.  Regular  mowing,
inspection,  erosion  control,  and debris and  litter
removal, are necessary to prevent significant sediment
buildup and vegetative overgrowth (Schueler, 1987).
Also,  periodic nuisance  and  pest control could be
required. Dry-pond  design  should recognize  these
maintenance requirements. The pond slopes should
allow for mowing, and access roads should be provided.
Limitations  on Use. Like other storm water treatment
structures used in large watersheds, a primary physical
constraint on the construction of water quality dry ponds
is their large land  requirements.  For this  reason,
locating dry ponds in new developments is usually more
practical than constructing them in already developed
areas.   Other   physical  constraints   include  the
topography and the depth to bedrock.
Wet Ponds. The design of wet ponds is similar to that
of dry ponds and constructed wetlands. In wet ponds,
storm water runoff is directed into an constructed pond
or enhanced natural pond, in which a permanent pool
of water is maintained until being  replaced with  runoff
as shown in Figure 7-3.  Once the capacity of  a wet
pond  is exceeded,  collected  runoff is  discharged
through an outlet structure or an emergency spillway.
Pollutant Removal.  The  primary  pollutant removal
mechanism in  wet ponds is settling. The ponds are
designed to collect storm water runoff during rainfall and
to detain it until additional storm water enters the pond
and displaces it. While the runoff is detained, settling of
particulates and associated pollutants takes place in the
pond.                                          ,

Wet ponds  can also remove pollutants from  runoff
through vegetative uptake.  Wet  ponds  should be
vegetated with native emergent aquatic plant species,
which  can  remove dissolved  pollutants  such as
nutrients from the runoff before it is discharged to the
receiving water.

Design Considerations.  Wet  ponds   typically  are
designed with a number of different water levels. One
level of the pond has a permanent pool of water. The
next level periodically is  inundated with water during
storms; this area should be vegetated and relatively flat
to promote  settling  and filtering  of sediments and
vegetative uptake of nutrients. The highest level will be
inundated only during extremely heavy rainfall; this area
also should be vegetated to prevent soil erosion. At
least 30 percent of the surface area of a wet pond
should be a vegetated zone (Livingston et aL, 1988).
Typically, this vegetation is concentrated at the outlet as
a final  "polishing" biofilter.
The sizing of wet ponds is similar to that of dry ponds
in that a number of different "sizing  rules"  provide
varying levels of pollution control. Generally, these rules
specify the volume of runoff to be detained in the Wet
pond during a storm. For example, the Maryland Water
Resources Authority specifies that the permanent pool
of a wet  pond should  be  large enough to contain
one-half inch of runoff distributed over the impervious
portion of the contributing watershed (MD WRA, 1986).
In Florida, storage volume for 1 inch of runoff above the
normal pool elevation is recommended. This volume
must be released  at a slow rate;  no more than half
should be discharged within 60 hours after the event,
and all the volume must be released after 120 hours. A
hydraulic retention time of 14 days for the permanent
pool volume is recommended (Livingston et al., 1988).

The design of water quality wet ponds must also take
into consideration  the  possibility of  large  storms.
Emergency spillways should be included in the design
to prevent flooding difficulties. In addition, the pond's
inlet and outlet structures  should  be separated and
constructed  at either end of the pond to maximize full
mixing  when  large  flows  occur  and  avoid  short-
circuiting.  By separating the inlet from  the outlet, the
detention time of the pond can also be increased. A
forebay or other system for pretreatment also might be
advisable. Further design guidelines for wet ponds can
be found in the  references in Appendix B.

Maintenance Requirements. Like many other BMPs,
wet ponds require routine maintenance to be effective.
Wet ponds are designed  to allow for settling  of
suspended solids;  therefore, periodic removal of the
accumulated sediment must be performed  (perhaps
                                                  113

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                                              Cross Section
                                                                                 Top of embankment

                                                                                        Max. safety storm WSE

                                                                                      imergenoy spillway Inverted
                                                                                              Riser crest
                   Safety storm passage
           2-yr storm water management storage
                Extended detention (ED) storage
                                                             %£%%#^^
                                                               £>^^
      Note: Figure not to scale.
                                                                      Antiseep collars
                                                 Plan View


                            - Max. safety storm water surface elevation (WSE)
    Max. extended
    detention (ED) WSE
       r— wax. saieiy storm water sunace elevation (wst)

X.   J^"'	  /—Max 2-yr stormWSE_             *'—



                  "
                                                                                        Embankment
   "
                                                                                                 Riser in
                                                                                                 embankment
                                                                                                      Outlet
                                                                                                      protected
                                                                                                      by riprap
                 '  "«^T^: Max. ED WSE—^	£^ /
                  """* -.*>	 Max". 2-yr storm WSE- - "  J$\
                           ---_    .	*       <£•£**
                                    -
                                                                                                  Emergency
                                                                                                  spillway
                                                          Max. safety storm WSE
Figure 7-3.  Wet detention system (Roesner et al., 1988).
                                                       114

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every  10 to  20 years). Removed sediment  must be
disposed of in accordance with appropriate regulations,
which  could  include  testing and  special  handling
requirements for contaminated material. In addition, the
pond slopes  should  be regularly  mowed to make the
sediment removal process easier and to enhance the
aesthetic qualities of the area. Inlet and outlet structures
should  be  inspected  periodically  for  damage  and
accumulated litter, and the  pond bottom  should be
inspected for potential  erosion.  Erosion of the pond
bottom from high velocity flows can result in increased
sediment transport and overall reduction in the pollutant
removal capabilities of the pond.

Limitations on Use. Water quality wet ponds have large
land requirements and usually are more suited to new
development projects where they can be designed into
the site. In addition, wet ponds are not suitable for use
in areas with porous soils  or low ground-water levels
because a pool of water in the bottom is key to  their
design. Wet ponds should be built into the ground water
with their  control elevation  set  above  the  level  of
seasonal  high water tables.  Synthetic  impermeable
materials or clay can be used to prevent seepage. Wet
ponds also have physical limitations related to the site
topography; since locating wet  ponds in areas  with
extreme slopes is often difficult, relatively flat locations
are preferable.

Constructed  Wetlands.  Constructed wetlands are
effective   in  removing   many  urban  storm  water
pollutants.  Two  prevalent  types  of  systems  are
shallow-constructed  wetlands (Figure 7-4)  and  wet
detention  systems  (Figure  7-5). The wet detention
system is a wet pond with extensive shoreline shallow
wetland areas. Wetland systems combine the  pollutant
removal capabilities of structural storm water controls
with the flood attenuation provided by natural wetlands.
Proper design of constructed wetlands—including their
configuration, proper use of pretreatment techniques to
remove sediments and petroleum products, and choice
of vegetation—is  crucial  to the  functioning of the
system.

Pollutant  Removal.   Constructed  wetland   systems
perform a series  of pollutant removal  mechanisms
including sedimentation, filtration, adsorption, microbial
               Inflow
      Level spreader
      mechanism
                                                                                            Outflow
Figure 7-4.  Example shallow-constructed wetland system design for storm water treatment (Maryland DNR, 1987).
                                                                                   Outflow
                 Sediment sump
                                                                                       Oil/grease
                                                                                       skimmer
                                                                        (10:1 desirable;
                                                                   4:1 minimum)
                                             Deeper area


Figure 7-5.  Example wet detention system design for storm water treatment (Livingston et at., 1988).
                                                  115

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decomposition,  and  vegetative  uptake  to  remove
sediment,  nutrients,  oil  and  grease,  bacteria, and
metals. Wetland systems reduce runoff velocity, thereby
promoting  settling of  suspended solids. Plant uptake
accounts  for  removal of dissolved constituents.  In
addition, plant material can serve as an effective filter
medium, and denitrification in the wetland can remove
nitrogen. A review  of pollutant removal effectiveness
data for 15 constructed wetlands and 11 natural wetland
systems designed  to treat  storm water  found high
removals of total suspended solids and lead and only
fair removal of ammonia, total phosphorus, and zinc
(U.S. EPA, 1992a). In addition, constructed wetlands
were found to have higher average removal rates and
less variability than natural systems (U.S. EPA, 1992a).
Specific wetland vegetation  species remove specific
pollutants  from  storm water  runoff (RIDEM,  1989).
Some of the most commonly used wetland vegetation
includes cattails, bulrushes, and canary grass.
Design Considerations.  Because the use of wetland
systems for storm water runoff control is a relatively new
technology, generally  accepted design  criteria do not
exist.  Some   general   guidelines,  however,   are
recognized  as important in  the design  of  wetland
systems.  These  guidelines   include maximizing  the
detention   time  of  runoff in the  wetland  system,
maximizing the distance between the inlet and outlet,
and providing some form of pretreatment for sediment
removal.
Maximizing the travel  time of runoff through a wetland
system allows for greater opportunity for sediments to
settle out of the water and for wetland plants to take
up nutrients and other pollutants. Travel time can be
increased in a wetland by reducing the gradient over
which the  flow travels or by  making the flow travel
over a greater distance before being discharged. In
either case, some  designers recommend a 24-hour
detention  time  during  the  1-year,  24-hour  storm
(RIDEM, 1989). if  the distance separating the inlet
from the outlet in a wetland system is not sufficient,
flow might enter the wetland system and not become
fully mixed during large rainstorms (see also the wet
pond discussion).  This  phenomenon,  known as
short-circuiting,  can  greatly  reduce  the wetland
system's level  of treatment. Short-circuiting can be
reduced by careful design  of the wetland system.
Wetland design should also  take into account that
sediment  accumulation   in  wetland  systems can
greatly  shorten their effective  life and  that  some
suspended solids should be removed from the runoff
before it  enters the wetland system. The  design
should include sloped sides to allow easy removal of
accumulated sediments and harvesting of  plants.
Recommendations  for constructed wetland systems
are  expected   to  evolve  as  more  research  is
conducted.
Maintenance Requirements. Like most storm water
quality controls,  constructed wetlands require regular
maintenance.  In  addition  to   regularly  scheduled
sediment   removal,  wetland  systems  should  be
periodically cleared of dead vegetation. Harvesting of
plants in the wetland might be appropriate for pollutant
removal purposes; if so, disposal of removed material
must be planned.

Limitations on Use. While constructed wetland systems
can treat storm water runoff effectively, they do require
large areas of undeveloped land, which can make siting
of wetland systems difficult especially in urban areas.
For this reason, incorporating wetland systems into new
development is usually more feasible than retrofitting
them  into  existing  developments. Existing wetlands
occasionally can be retrofitted for pollutant removal if
not prohibited by local or  state regulations. Achieving
proper soil conditions and ground-water levels can also
present difficulties. To maintain a  wetland environment,
soils must be resistant to infiltration (i.e.,  have  low
permeability) and a water supply must be constant. In
general,  soils  in  the  system  must be  saturated
throughout  the   growing   season  so  the   desired
vegetation  will  survive.  Since  natural wetlands  are
protected  resources, diverting storm water to them for
treatment will likely be   prohibited.  Finally,  created
wetlands become a resource area that may be subject
to protection under federal, state, and local laws.

Infiltration Facilities
Unlike detention facilities that capture and eventually
release storm water runoff to a surface water body,
infiltration facilities permanently capture runoff so that it
soaks  into the ground water. Because they do  not
release the runoff to a surface water, infiltration facilities
are sometimes  called  retention facilities.   Pollutant
removal  in these  BMPs  occurs primarily  through
infiltration, which eliminates the runoff volume or lowers
it by the capacity of the facility. Since the infiltrated flow
can travel through the ground water and still be released
to surface waters, dissolved pollutants such as some
nutrients and metals could be  reintroduced  to  the
surface water with minimal pollutant removal. Currently,
the three different types of facilities commonly used to
promote infiltration and remove pollutants from storm
water   runoff  are   infiltration   basins,  infiltration
trenches/dry  wells,   and  porous  pavement  (grassed
swales, which also promote infiltration, are addressed
later under vegetative practices). Each of these BMPs
is discussed  in  this section.   For  detailed design
information, the references listed  in Appendix B should
be consulted.
Infiltration Basins. Infiltration basins are similar to dry
ponds, except that  infiltration basins  have  only an
emergency spillway and no standard outlet structure.
                                                  116

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All flow entering an infiltration basin (up to the capacity
of the basin) is, therefore, retained and allowed to
infiltrate into the soil (see Figure 7-6).

Pollutant Removal. Infiltration  is the  major pollutant
removal mechanism. Infiltration basins, like dry and wet
ponds,  receive storm water  runoff  from  drainage
systems and provide storage up to a designed volume.
Unlike dry detention  ponds which  eventually release
stored runoff through  a drainage system, or wet ponds
which maintain a permanent pool of water, infiltration
basins  release stored  runoff  through  the  basin's
underlying  soil.  Infiltration basins provide storm water
pollutant  removal  through  volume  reduction   and
filtration and settling.  Infiltration basins are particularly
effective  in  removing bacteria,  suspended  solids,
insoluble nutrients, oil and grease, and floating wastes.
They are less effective in removing dissolved nutrients,
some  toxic  pollutants,  and   chlorides.  Therefore
infiltration  basins  should  not  be  used when  the
ground-water quality itself is a concern or when these
pollutants can  be reintroduced through  ground-water
flow to surface waters.

Design Considerations. The most important consideration
in the design of infiltration basins  is calculating the
basin's size  for the drainage area and the soil type
involved. Some designers recommend off-line basins to
capture and  infiltrate the first one-half inch of rainfall
from the contributing  drainage area (MD WRA, 1986).
The appropriate amount of flow must be diverted to the
system, and soil tests need to be performed to estimate
the infiltration rates and appropriately size the basin.
Also related to the proper size of infiltration basins is the
amount of time necessary for the basin  bottom to dry
between rainstorms.  Designers generally specify that
               infiltration basins should be designed to be dry for at
               least 3 days between  storms (Schueler,  1987). This
               interval allows the soil to  dry, thereby increasing  its
               pollutant  removal  capacity.   Basin  shape  is  also
               important. It should have gently sloping sides to allow
               for easy access to mow the bottom  vegetation.  An
               emergency  spillway must also be incorporated into the
               basin  design.  Finally, some  form of pretreatment is
               recommended to remove suspended sediments from
               runoff before  it is  discharged to  the  basin. This
               pretreatment will reduce the need for periodic removal
               of accumulated sediment which can clog the soil pores
               and reduce the level of infiltration.

               Maintenance Requirements. Infiltration basins require
               moderate to high levels of periodic maintenance. Most
               are designed with  vegetated  bottoms  to provide
               stabilization and promote some vegetative  uptake of
               nutrients. Periodically, the bottom of the basin must be
               mowed and accumulated sediments must  be removed
               to maintain  desired infiltration rates.

               Limitations   on Use.  Infiltration  basins  often  have
               relatively large land requirements and are better suited
               for  location  in  developing  areas  than  in already
               developed areas. Infiltration basins also require suitable
               soil to be effective. Accumulating runoff must be able to
               infiltrate the soil  in the bottom of the basin. Typically,
               sand and loam,  with infiltration rates greater than or
               equal to 0.27 in/hr  (WA DOE,  1991), are the preferred
               soils for  infiltration systems.  The  use of  infiltration
               basins can  be   restricted   by  high  ground-water
               elevations.  For infiltration to occur, ground-water levels
               should be located at least 2 to 4 feet below the bottom
               of the basin.
        Top view
   Riprap
   outfall
   protection
                                                                         Riprap
                                                                         settling
                                                                         basin and '*
                                                                         level spreader
Flat basin floor with
dense grass turf
Figure 7-6. Sample infiltration basin.
                                                   117

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Infiltration Trenches/Dry Wells. Subsurface infiltration
practices, such as infiltration  trenches or dry wells,
force runoff into the soil to recharge ground water and
remove  pollutants. These infiltration  structures  are
located below  ground and usually  must be  built  "off
line" because of their limited storage area (see Figure
7-7). Subsurface infiltration systems generally consist
of precast concrete structures with  holes in the sides
and bottom surrounded by 2 to 4 feet of washed stone.
Storm water runoff is directed into these structures and
infiltration takes place.
Pollutant Removal. The structural controls described in
this section use  filtration  as  the  primary  pollutant
removal  mechanism,  much  like onsite  wastewater
treatment systems commonly  used  in  many  small
communities.   These  controls  effectively   remove
suspended  sediments and  floating  debris, as well as
bacteria   which   are  difficult   to   remove  without
disinfection.  Infiltration practices are  generally  less
effective  at  removing  dissolved nutrients,  such as
nitrogen or other soluble contaminants, which can travel
through  ground  water  and be discharged to  the
receiving water.
Design  Considerations.  The  soil  infiltration  rate is
probably the most important consideration in the design
of  infiltration  structures.  The  soils  underlying  the
structure must be tested to determine their suitability for
infiltration. Some authorities specify the types of soils
acceptable for  infiltration as noted above for infiltration
basins. Structure size is another primary consideration.
                                         The structures  must be large  enough  to  handle the
                                         desired design  storms. Also, the  structures must be
                                         designed  to  allow larger storms to  bypass  them.
                                         Because subsurface infiltration  structures do not have
                                         outlets, they usually have to be  designed off line of the
                                         regular drainage  system. Runoff  can then enter the
                                         infiltration  structure until it is full;  additional runoff is
                                         directed away from the structure. A diversion structure
                                         upstream of the infiltration structure is normally part of
                                         the design. The flow entering this structure (which could
                                         be a simple  manhole) is directed to the  subsurface
                                         infiltration structure until it is full; then additional flow is
                                         directed away from the  structure and along the drainage
                                         system. A typical sizing rule for subsurface infiltration
                                         structures  is they should store the runoff from the first
                                         one-half inch  of rainfall on the site  (Livingston  et al.,
                                         1988).

                                         Infiltration structures must also be designed to empty in
                                         a reasonable length of time. The  underlying soils, to
                                         remove pollutants  from  runoff effectively,  must be
                                         allowed to dry between  rainstorms.  Most experts specify
                                         that infiltration structures should contain a  reservoir of
                                         runoff for no  more than 3 days after rainfall (Shaver,
                                         1986).

                                         Maintenance Requirements. Infiltration structures require
                                         periodic cleaning to remove accumulated sediment and
                                         petroleum products. Often the need for this maintenance
                                         can be reduced  by incorporating into the design a
                                         pretreatment  structure  that removes  sediments  and
                                         petroleum products from the runoff. These pretreatment
                                              Dike
                                                             20 ft minimum vegetated strip
Filter fabric
                                 Aggregate
                                                   3 ft minimum
                                                   depth
                                                        Filter fabric
Rguro 7-7. Sample infiltration trench (Livingston et al., 1988).
                                                    118

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structures can also minimize the discharge to ground
water  of some  pollutants,  such  as  solids.  While
addressing these  issues  in the  design of infiltration
structures can reduce routine maintenance requirements,
the design still should include an  observation well that
allows inspectors to determine sediment deposition.
Limitations on  Use. Subsurface  infiltration structures
can be used for end-of-pipe treatment as well  as  be
located at different points in the drainage system. If
located at the downstream end of a drainage system,
infiltration structures can have large land requirements.
Subsurface  infiltration  structures,  because  they  are
located underground, can be located in areas such as
parking lots and access roads.
The primary  physical  limitation to locating infiltration
structures, other  than  land  requirements,  is  the
suitability  of   soil,   which  must  be  neither  too
impermeable to runoff  (e.g., clay,  silt,  or till) nor too
rapidly  permeated  (e.g.,  sand).  Another potential
physical limitation is the depth  to ground water.  To
provide proper treatment  and reduce the possibility of
ground-water contamination, a distance of at least 2 feet
should be maintained between  the  bottom  of  the
infiltration structure and the mean high ground-water
elevation.
Porous Pavement. Paved roads and  parking  areas,
because they increase  watershed imperviousness, are
major contributors to storm water runoff problems in
urban areas. Porous pavement, however, allows water
to  flow  through a  porous asphalt layer and into  an
underground gravel  bed. Porous  concrete pavement
can also be used. Use of this porous pavement can
thereby reduce runoff volume and pollutant discharge.
This practice,  used  in areas  with  gentle  slopes, is
generally designed into parking areas that receive light
vehicle traffic.
Pollutant  Removal.  Field  studies have  shown that
porous pavement systems can remove significant levels
of both soluble and paniculate pollutants (Schueler,
1987).  Porous  pavement  is  primarily  designed  to
remove pollutants deposited from  the atmosphere, as
coarse solids can clog the pavement pores. In these
systems,  pollutant removal occurs primarily after the
runoff  has infiltrated  into the underlying soils. Pollutant
removal is accomplished by trapping of sediments, and
infiltration  through   the  underlying  soils  which  can
remove  pollutants   such as  bacteria.  The  removal
efficiency depends  on  the storage volume  of the
pavement,  the basin  surface area,  and the  soil
percolation  rate (U.S. EPA,  1991b).
Design  Considerations.  Porous  asphalt  pavement
generally is designed with an upper  pavement layer 2-
to 4-inches  thick, a 1- to 2-inch layer of coarse sand, a
stone  reservoir to provide  storage, and a bottom filter
fabric  as  shown in Figure 7-8. Other types of porous
pavement  include   poured-in-place  concrete  slabs,
pre-cast concrete grids, and modular units of brick or
cast concrete (Livingston et al., 1988). The differences
in pavement design result in  different ways that the
collected  runoff is discharged. Some systems let all the
runoff discharge through the underlying soils and into
                                                           im
                                                               Porous asphalt: Coarse asphaltic
                                                               mix (1/2- to 3/4-in aggregate)
                                                               in a layer that is 21/2 to 4 in thick.
                                                                Filter: Coarse (i.e., 1/2-in)
                                                                aggregate in a layer that is
                                                                2 in thick.
                                                                Reservoir: Coarse (i.e., 1- to 2-in)
                                                                aggregate; voids are designed for
                                                                runoff detention. Thickness of layer
                                                                depends on storage required
                                                                and frost penetration.
        '	Filter fabric	

         Existing soil: Minimal compaction,
         so that porosity and permeability
         are retained.
 Figure 7-8.  Porous pavement cross section (WA DOE, 1991).
                                                    119

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 the ground water. While these systems provide good
 pollutant  removal, they can result  in  ground-water
 contamination. Other systems include perforated pipes
 to collect the runoff and discharge it directly to a surface
 water; while these systems  protect the  ground water
 below the pavement, they do not provide the same level
 of pollution removal as the full infiltration systems.

 Porous pavement is designed so that a certain amount
 of runoff is collected and stored in the stone reservoir.
 The design criteria, therefore, determines the depth of
 the stone reservoir. The maximum depth of the stone
 reservoir also is affected by  the infiltration rate of the
 underlying soils. Runoff should be completely drained
 within a maximum of 3 days after the maximum design
 storm event  to  allow the  underlying  soils  to dry,
 maintaining aerobic conditions that improve pollutant
 removal (Schueler, 1987).

 Maintenance  Requirements.  Porous  pavement can
 have  extensive  maintenance   requirements.  The
 pavement must be kept free of coarse particles that can
 clog the pavement and prevent runoff from  collecting.
 The pavement must, therefore, be regularly inspected
 and cleaned with a vacuum sweeper and high pressure
 jet The state of  Maryland,  by reviewing its porous
 pavement practices, found that after 4 years of use only
 two of the 13  systems were functioning as designed
 (Lindsey etal., 1991). The 11  malfunctioning sites were
 affected primarily by clogging and excessive sediment
 and debris.
 Limitations  on  Use.   Because porous  pavement  is
 expensive to replace or repair, it is generally only used
 on  parking areas that  receive moderate to low traffic.
 The area to be paved also should be relatively flat with
 a depth of 2  to 4 feet from  the  bottom of  the stone
reservoir to the high water table. In addition, the soils
under the pavement must allow for infiltration.

Vegetative Practices

Urbanization results in the elimination of vegetation and
increases in impervious area. Vegetative practices in
urban areas decrease the impervious area and promote
runoff infiltration and solids capture. These practices
generally provide moderate to low pollutant removal and
are therefore used as pretreatment for the removal of
suspended solids from runoff prior to more intensive
treatment by other practices. The  two  major types of
vegetative practices commonly used in urban areas are
grassed  swales  and  filter strips  (both  sometimes
referred   to  as   biofliters).  Native   vegetation  is
recommended since it requires less site preparation and
maintenance.

Grassed  Swales.  Grassed  swales  are  channels
covered with vegetation to reduce erosion of soil during
storms (see  Figure 7-9). They are used to  replace
conventional catch basin and pipe network systems for
transporting runoff  to  surface waters. Storm water
runoff flows through the grassed swale reducing runoff
velocity and  promoting  the removal  of  suspended
solids.

Pollutant  Removal.  Infiltration  of the runoff  and
associated pollutants is the most  important pollutant
removal  process  accomplished by grassed  swales.
Grassed swales also remove pollutants through  filtering
by the vegetation and settling of solids in low-flow areas.
Because  of  these pollutant  removal  mechanisms,
swales are most effective at removing suspended solids
and  associated  pollutants,  such  as  metals.  The
mechanism of infiltration also allows  removal of bacteria.
             Erosion control
             seed mix or sod —,
                                       Trapezoidal Cross Section
                                                                                   Minimum
                                                                                   freeboard
                           Channel bottom
                           sloped for proper
                           flow conveyance
            Erosion control blanket

         Seed mix (ref. plant list)

         Topsoil, 4 in min. depth
Figure 7-9.  Sample grass-lined swale (Horner, 1988).
                                                  120

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Grassed swales provide little  removal of dissolved
pollutants, such as nutrients. Based on many studies of
grassed swale effectiveness, removal rates are high for
metals and particulates (Pitt, 1989).

Design Considerations. Pollutant  removal in grassed
swales can be increased by reducing runoff velocity—
reducing the slope, increasing the vegetation density,
and installing check dams to promote ponding. Also, the
underlying soils should have a high permeability to help
promote infiltration.

Maintenance Requirements. Grassed swale maintenance
is aimed at preserving dense vegetation and preventing
erqsion of underlying soils. This maintenance includes
regular mowing, weed removal, and watering during
drought periods and after initial seeding. In conjunction
with  mowing, the cut material should be removed.

Limitations on Use. Grassed swales might be difficult to
retrofit in already developed areas. They can replace
curb and  gutter drainage systems, but work best in
low-slope areas with  soil  that is not  susceptible to
erosion.

Filter  Strips. Filter strips,  shown in Figure 7-10, are
similar  to  grassed  swales.  Runoff entering  these
systems, however, generally is sheet flow, is evenly
distributed   across   the  filter  strip,   and  flows
perpendicular to the filter strip. Because these  systems
can accept only overland sheet flow,  level spreading
devices are used so that water is not ponded.

Pollutant Removal.  Pollutant removal in  filter strips
depends on the filter strip's length, size, slope, and soil
permeability; the size of the watershed; and the runoff
velocity (Horner, 1988). Filter strips are most  effective
at removing pollutants such  as  sediment,  organic
material, and some trace metals, and  less effective at
removing dissolved pollutants such as  nutrients.

Design Considerations. The  major design aspects of
filter strips  that can  be effectively  changed  are the
length, width, slope, and vegetative  cover of the strip.
Greater pollutant removal results from filter strips that
are long and flat. A level spreading device must also be
incorporated in the design of a filter strip to ensure that
concentrated flow does not enter and create a  channel.
If concentrated flows enter a filter strip, they can cause
erosion of  the  vegetation and soil and reduce the
structure's  pollutant removal efficiencies. In addition to
these considerations, filter strips should be constructed
in areas with porous soil to promote infiltration.
                                         Grassed
                                           area
                                      (plants and trees)
                                  Stone trench
                                  level spreader
Figure 7-10.  Schematic design of a filter strip.
                                                   121

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 Maintenance  Requirements.  Filter  strips  must  be
 mowed and weeded regularly—the same maintenance
 practices as grassed swales. In addition, the strip must
 be watered  after initial  seeding. In  some cases,
 however, large filter strips can be "left on their own" so
 that large vegetation can grow and create a natural filter
 strip. This option reduces the level of maintenance
 required and can enhance the  pollution removal of the
 strip.

 Limitations on Use. The major limitation on the use of
 filter strips is the slope of the land; these strips operate
 best when placed on flat surfaces that have permeable
 soils. Also, filter strips treating large watersheds can
 have  large  land  requirements that  preclude  their
 location in urban areas.

 Filtration Practices

 Filtration  practices provide  runoff treatment through
 settling and filtering using a specially placed layer of
 sand  or other filtration  medium.  Flow  enters the
 structure, ponds for a period of time, and filters through
 the media to an underdrain that discharges to a surface
 water. These practices attempt to simulate the pollutant
 removal of Infiltration  practices using  less land  area.
 Two different types of filtration practices currently in use
 are filtration basins and sand filters.
 Filtration Basins. Storm  water runoff  diverted to a
 filtration  basin  can be detained, allowed to percolate
 through filter media, and collected in perforated pipes
 as shown in Figure 7-11. These perforated pipes then
 transport the  filtered  runoff to the  receiving water.
 These systems have  been used extensively in Austin,
 Texas, showing  good pollutant removal  efficiencies
 and low failure rates  (City of  Austin,  TX, 1990).
 Communities in other  regions might experience some
 initial problems in importing the technology (U.S.  EPA,
 1991 a). One major question  regarding filtration basins
 Is  the  effect   of  cold  temperature   and  freezing
 conditions on the operation of these systems.

 Pollutant Removal. Pollutant removal in filtration basins
 occurs because of settling during the initial ponding time
                                      and   filtering  through   the   soil  media.   Removal
                                      efficiencies  in  filtration  basins  depend  on  several
                                      factors, including the storage  volume, detention time,
                                      and filter media used. In general, longer detention times
                                      increase the  system's  pollutant  removal  efficiency.
                                      Increasing   the   detention  time  usually  requires
                                      increasing the overall size of the filtration basin.

                                      Initial settling of suspended solids occurs in filtration
                                      basins during the initial ponding of the runoff. Increasing
                                      detention   time   therefore  promotes  settling  and
                                      increases the pollutant removal efficiency. Reducing the
                                      size of the perforated pipe, increasing the depth of filter
                                      medium, or decreasing the percolation rate of the filter
                                      medium can  be  used to increase the detention time.
                                      Changes in the  filter medium  also affect the pollutant
                                      removal efficiency of filtration basins. To date, filtration
                                      basins have primarily used sand as the filtering medium.
                                      Recent studies, however, have investigated the use of
                                      a combination of sand and peat,  taking advantage of
                                      the adsorptive properties of peat  to increase pollutant
                                      removal efficiencies (Galli, 1990). These  sand-peat
                                      systems, however,  are  generally untested  and  their
                                      pollutant removal efficiencies are only theoretical.

                                      Design Considerations. In Austin,  Texas, sand filtration
                                      basins are typically designed to provide a detention time
                                      of 4 to 6 hours and have  been  used to treat runoff from
                                      drainage areas from three to 80 acres (City of  Austin,
                                      TX,  1990). An  experimental  storm water  sand-peat
                                      filtration basin to  be constructed in Montgomery County,
                                      Maryland, is being designed to store the first one-half
                                      inch   of  rainfall   from the  impervious  land  in  the
                                      watershed. In the Maryland area, this sizing criterion
                                      results in the treatment of 50 to 60 percent of the annual
                                      storm runoff volume (Galli, 1990). Runoff from larger
                                      storms will exceed  the capacity  of  these filtration
                                      systems and will be diverted  away from the filtration
                                      basin or discharged through an emergency spillway. To
                                      improve the longevity of  sand and sand-peat filtration
                                      basins,  runoff  entering  the  systems  is  typically
                                      pretreated  to   remove   suspended   solids.   Such
                                      pretreatment  techniques  as the use of a wet pool or
n
Cleanout
  pipe
 n
                                                             i— Geotextile fabric
      i,,!	in	h	ill	i	
      r	
                           ! sia\n fine sand
                                  -8-in perforated pipe          "~ Geomembrane

Figure 7-11.  Conceptual design of a filtration basin (City of Austin, TX, 1990).
                                                   122

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water quality inlets can be used in  conjunction with
filtration basins.

Maintenance Requirements. Storm water runoff filtration
basins  require  extensive  maintenance  to  remove
accumulated sediments and prevent clogging of the
filtering medium.  Maintenance  requirements include
inspecting the basin after every major storm event 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 removed periodically and the filter medium,
when  clogged  with  sediment  deposits,  should  be
removed and replaced (U.S. EPA, 1991b).

Limitations  on  'Use.  Filtration basins  can  often  be
difficult to locate in highly urbanized areas because of
their large land requirements. In addition, high ground-
water levels can restrict their use. Finally, they have not
been widely used throughout the country and might not
be considered a proven technology.
Sand Filters. Sand filters are similar to the filtration
basins outlined above but can be built underground to
reduce the  amount of land required.  These  systems
consist of a catch basin for settling of heavy solids and
a filtration chamber (see Figure 7-12). Runoff enters
the catch  basin  and collects  to the  basin capacity,
overflows into a  sand-filled  chamber that  provides
filtration, and  is discharged through an outlet pipe in
the bottom  of the filtration chamber.  Other  types of
systems can  be  designed  in  conjunction  with  wet
ponds or other practices, using natural or imported soil
banks or  bottoms, to increase their pollutant removal
capability. The use of sand filters for storm water runoff
treatment   has  been   demonstrated  in   Maryland
(Shaver, 1991).

Pollutant Removal. Sand filters use the same pollution
removal  mechanisms as filtration  basins and provide
similar pollutant removal. Initial removal of heavy solids
occurs through settling in the catch basin and further
treatment is provided by filtration through the sand-filled
                                                   Plan View

                                                       Flow
                                                                                        Drain
                                                                                      Outfall pipe
                                                 Section A-A'

                                          Grated cover       Solid cover
                            Row
            1/2-in reinforcement bars
            6-in on center each way
                      3,000 PSI concrete
                                         Grate (fabric wrapped
                                         over entire grate opening)  —I
                                                                           Provide nipple, fittings,
                                                                           etc. as required
Figure 7-12.  Schematic design of sand filter (Shaver, 1991).
                                                    123

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 chamber.  Sand filters  are particularly  effective  at
 removing suspended solids and pollutants that attach to
 suspended solids, such as metals. Moderate removal of
 bacteria can be expected,  but these systems cannot
 provide removal of soluble pollutants such as  nitrogen
 and phosphorus.

 Design Considerations. Because this BMP has not been
 widely used, there  are few  generally accepted design
 criteria for sand filters. The catch basin section  must be
 designed to provide some  sediment removal and to
 ensure that flow enters the filtration chamber as sheet
 flow to prevent scouring of the sand. The maximum
 drainage area that  can be treated by a sand filter has
 been reported as about 5 acres (Shaver,  1991). Sand
 filters generally are used to treat impervious areas, such
 as parking lots, so that smaller sediment particles
 typical of pervious areas will not clog the sand filter.

 Maintenance Requirements. Sand filters require minimal
 maintenance,  consisting  of  periodically  removing
 accumulated sediment and the top layer of sand from
 the filtration  chamber  and  removing  accumulated
 sediment and floatables from the catch basin.  Regular
 inspections of the filter system can indicate when this
 maintenance is required.

 Limitations on Use.  Because of their small size, sand
 filters are designed to be used for pretreatment in large
 watersheds or full treatment in small watersheds. They
 cannot provide sufficient treatment for large watersheds
 (Shaver, 1991).

 Water Quality Inlets

 Water quality inlets, also known as oil and grit separators,
 are similar to septic tanks used for removing floatable
 wastes in onsite wastewater disposal systems. These
 inlets  provide   removal  of  floatable  wastes  and
 suspended solids through the use of a series of settling
 chambers and separation baffles as shown in Figure
 7-13. These systems have been designed and used for
 many  years,  but   storm   water pollutant  removal
 efficiencies are generally unknown.

 Given the limited pollutant removal expected from water
 quality inlets, they are usually used in conjunction with
 other  BMPs.  Fairly effective  at  removing  coarse
 sediments and floating wastes, water quality inlets can
 be  used to pretreat runoff before it is discharged to
 infiltration systems or detention facilities.  In this way,
 some of the routine  maintenance other BMPs  require
 (e.g.,   sediment   removal and  unclogging  of outlet
 structures) can be reduced. Water quality inlets also can
 serve to capture petroleum spills that could enter other
treatment structures or surface waters.

 Pollutant Removal.  The  primary pollutant removal
mechanisms of water quality inlets are separation and
settling. The use of three chambers in these inlets
 serves to increase the detention time of the runoff in the
 tank, allowing settling to occur. In this way, suspended
 solids, and the attached pollutants, are removed from
 the runoff. In addition, the use of baffles and inverted
 elbows helps to remove  floating litter and petroleum
 products from the storm water. The level of removal of
 these pollutants depends on the volume of water
 permanently detained in the tank, the velocity of flow
 through  the tank, and  the depth of the baffles and
 inverted elbows  in the  tank.  By increasing detention
 time and decreasing flow velocity, the level of sediment
 and floatables expected  to be removed from water
 quality inlets can be improved.

 Design  Considerations.  There  are  few  generally
 accepted design criteria for water quality inlets. Their
 design depends  on the size  of the watershed being
 treated  and  the  detention  time  required.  Since
 suggested detention times are usually  measured in
 terms of minutes rather than days, water quality inlets
 generally do not remove  pollutants from storm water
 runoff as effectively as some of the more intensive
 detention facilities discussed  in this section.  Water
 quality inlets have the  advantage of being relatively
 small  so  they can be  placed throughout a drainage
 system rather than just  at the downstream end of the
 system.

 In water quality inlet design, provisions should be made
 to  reduce the  entering flow  velocity. Sediment  and
 petroleum products collect in the water quality inlets. If
 entering  flow has  a  sufficiently  high  velocity,   the
 accumulated pollutants can  be  resuspended  and
 discharged from the inlet.  The flow and velocity of the
 entering runoff can be hydraulically restricted by limiting
 the  size  of  the  inlet pipe. Flows greater  than  the
 maximum design flow should be diverted away from the
 water  quality inlet  by  a  diversion structure  in  an
 upstream manhole.

 Maintenance Requirements. Water quality inlets require
 periodic maintenance to remove accumulated pollutants;
 in general, these inlets should  be cleaned about twice
 a year. Cleaning  can be performed with a vacuum truck
 similar to those used to  clean catch basins. The waste
 removed  from  water quality  inlets,  which includes
 petroleum products  as  well as  sediments that have
 accumulated in   the bottom,  should  be  tested  to
 determine proper disposal requirements, though their
 characteristics are similar to  those  of  catch  basin
 wastes.  Periodic  inspections  between  scheduled
 maintenance are also required to determine the level of
 accumulated pollutants.

 Limitations  on   Use. There   are  few  physical  site
 limitations on the use of  water  quality inlets. The inlets
are generally designed as  belowground structures and
do not require large amounts of land. Given their small
size, however, large watersheds cannot be drained into
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a water quality inlet. Removal.efficiencies depend on
the detention  time in the water quality inlets. Their use
is usually restricted  to small watersheds of less than 2
acres. Another restriction on  the use of water quality
inlets is dry-weather base flow. If dry-weather base flow
cannot easily be removed from a drainage system, a
larger water quality inlet and more frequent maintenance
are needed to accommodate this flow as well as the
flow resulting from a rainfall event.

Combined Sewer Overflow Control Practices

Some of the urban  runoff BMPs discussed above are
applicable to CSO control. Additional control  practices
commonly used for  CSO control are described in this
section,   including  a  general  discussion  of  each
practice's applicability, its pollutant removal effectiveness,
                                                         • 12-in compacted 3/4-in stone
             and  its  maintenance  requirements.  More  detailed
             references on CSO control are presented in Appendix
             B. Because CSOs contain sanitary sewage and other
             waste streams,  the  primary  pollutants of  concern  in
             CSO control are suspended solids, biochemical oxygen
             demand, and pathogens. CSOs, however, also contain
             nutrients, metals, and other toxic substances.

             Source Controls
             Many of the source control practices that address urban
             runoff pollution are applicable to  CSOs because they
             address  contaminants that can enter any storm water
             collection  system,  whether  separate or  combined.
             Additional  source  control measures  include water
             conservation and pretreatment programs.
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 Water Conservation Programs, One way of reducing
 the  amount of sewage in a combined system  is to
 attempt to control the amount of water used by homes
 and businesses that is then converted to wastewater.
 Typical programs and practices for control include:

 •  Plumbing retrofit: Using  low-flush toilets, flush dams,
   faucet aerators, and other water-saving devices.

 •  Plumbing code changes: Requiring implementation
   of water-saving devices in new construction or as
   they are replaced.

 •  Education programs: Encouraging water conservation
   in businesses and homes by providing information on
   its benefits.

 •  Technical assistance: Providing water-use audits or
   case  studies demonstrating potential  savings to
   businesses.

 •  Rate system modifications: Adjusting rate systems to
   promote or reward water savings.

 While these programs might require minor changes in
 personal habits, they can be cost effective compared to
 end-of-pipe treatment. There are limits, however, to the
 reductions in  water  use  that  can  be  achieved
 reasonably.

 Pretreatment  Programs.   These   programs   are
 Implemented at the  local level to control industrial and
 commercial  sources of  wastewater discharging  to a
 municipal sewer  system.  The  goals  of a  local
 pretreatment program are  to stop or prevent industrial
 and  commercial pollutants  from  passing through a
 municipal wastewater treatment plant, thereby violating
 state water  quality standards; to  stop or prevent
 disruption of treatment plant operations  caused  by
 industrial  and  commercial  pollutants,- including the
 contamination of municipal treatment plant residuals;
 and  to ensure the safety  of municipal sewer system
 and  treatment  plant workers by   minimizing  their
 exposure  to potentially dangerous or toxic pollutants.
 While   pretreatment   programs   historically    have
 controlled  large   industrial  wastewater   sources,
 programs increasingly are focusing on controlling the
 discharges from small  businesses  and  households.
 Local pretreatment  programs  typically  include  the
following activities:

 • Development of sewer-use regulations: To establish
  requirements  on  the  quality  and  quantity  of
  nondomestic wastewater that can be discharged to a
  municipal   sewer  system  and  to  provide   the
  municipality with legal authority to ensure compliance
  with pretreatment requirements.

• Monitoring and surveillance: To sample and analyze
  industrial and commercial discharges and to conduct
  onsite  inspections  of  industrial  and  commercial
  facilities   to  determine   the  compliance   with
  pretreatment requirements.

• Permitting and  enforcement:  To issue permits to
  individual  industrial  and  commercial wastewater
  discharges that  establish  site-specific pretreatment
  requirements and to take all  necessary actions to
  ensure compliance with those requirements.

• Technical assistance  and education programs: To
  provide assistance to the regulated  industries  and
  commercial facilities, including encouragement to use
  pollution  prevention measures to address wastewater
  control problems and to educate the general public
  on the effects of common household products  and
  wastes that are discharged to the sewer system.

A pretreatment program  implemented in a municipality
with combined  sewers can help  control industrial  and
commercial pollutants discharged from CSOs during
storm  events.  The  level to  which a pretreatment
program can control the quality of CSO discharges,
however, is very difficult to determine. Nonetheless, as
part of an overall program to decrease the deleterious
effects of CSOs, a pretreatment program can provide
positive results.

Collection System Controls

Many collection system  controls exist for addressing
pollution from CSO discharges. These controls focus on
modifying  the  sewer system  to reduce CSO flow,
volume, and contaminant load.

Sewer Separation. One method for addressing CSO
pollution is to convert the combined collection system
to separate storm water and sanitary sewer systems by
constructing a  new separate sanitary  sewer.  Sewer
laterals  from  homes   and  businesses  are  then
connected   into   the  new  system.   Inappropriate
connections to the old  system  from  buildings  are
plugged. This conversion eliminates the possibility of
sanitary wastes entering the  drainage system  and
being discharged to a surface water. Sewer separation,
however, can be  very  expensive and  disruptive. A
municipality implementing  this practice  likely has to
address urban  runoff pollution problems. In  systems
that consist of both combined and separate drainage
areas, partial separation  (i.e.,  separation  of some
combined areas) could be cost-effective.

Infiltration  Control. Sources of  infiltration  include
ground water entering the collection system through
defective pipe joints, cracked or broken pipes,  and
manholes  as  well as  footing   drains  and  springs.
Infiltration flow rates tend to be relatively constant, and
result in lower volumes  than  inflow  contributions.
Infiltration problems are usually not isolated, and often
reflect a more general  sewer (or drainage)  system
deterioration. Extensive rehabilitation is typically required
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to remove  infiltration  effectively.  The rehabilitation
effort often  must include house laterals, which  are
normally a  significant  source.  Except in very large
drainage systems, control of infiltration generally has a
much smaller impact on CSO reduction  than control
applied to inflow.

Inflow  Control. CSO  control  can  be achieved  by
diverting some of the surface runoff inflows from the
combined sewer system, or  by  retarding the rate at
which these flows are  permitted to enter the system.
Inflow  of surface  runoff can be  retarded  by using
special gratings, restricted outlet pipes, or hydrobrakes
(or comparable commercial devices)  to modify catch
basin inlets to restrict the rate  at which surface runoff is
permitted to enter the  conveyance system.  Inlet flow
restrictions can be designed to produce acceptable
levels of temporary ponding  on  streets or parking lot
surfaces, allowing runoff to enter the system eventually
at the inflow point, but reducing the  peak flow rates that
the  combined  sewer system  experiences.  Flow
detention to delay the entry of runoff into the collection
system by storing  it temporarily and  releasing it at a
controlled rate can also be accomplished by rooftop
storage  under appropriate conditions. Elimination of
the  direct  connection   of  roof  drains to the  CSO
collection system and causing this runoff to  reach the
system inlets by overland flow patterns (preferably via
unpaved or vegetated  areas) is another method of
retarding inflows.
When site conditions permit, some  surface runoff flows
can  be prevented from entering the combined system,
by diverting them via overland flow to pervious areas or
to separate storm drains. When these outlets are not
available, excess surface runoff flows can be diverted
to more favorable locations  in the combined system
(called flow-slipping).

Regulator and System Maintenance. Malfunctioning
regulators are a common problem for combined sewer
systems and  can  result in dry-weather  overflows  to
receiving waters or  in  system backups and flooding.
Static regulators often malfunction because of plugging
or interference by debris  in  the  sewer  system.
Mechanical  regulators  tend  to   require   frequent
maintenance. Municipalities should, therefore, develop
an inspection and maintenance program designed  to
keep these  regulators operating  as designed.  The
expected reduction in  CSO flows  and loads resulting
from this maintenance  is site specific and depends on
the existing conditions in the system.

In-System   Modifications.   These  practices  are
designed to reduce CSO discharges  by modifying the
system to store more flow and allow it to be carried to
the  treatment plant.  Possible  modifications include
adjusting regulator  control  features, such  as  weir
elevation; installing new regulators; or installing  new
relief  conduits.  The effectiveness and  applicability of
these practices  is site specific and  depends  on the
existing capacity of the system and the treatment plant.
These practices  can be  cost  effective  in  locations
where excess capacity exists.

Sewer  Flushing. Sewer  flushing  is  an additional
practice to address  CSO pollution  problems.  In this
practice, water is used to flush deposited solids from
the combined system to the treatment plant during dry
weather. This practice is typically used  in flat areas of
the collection system where  solids are most likely to
settle out. The  effectiveness of  this practice is site
specific  and depends  on  the flush  volume;  flush
discharge rate;  wastewater flow; and  sewer  length,
slope, and diameter. Though not currently a widely
used  practice,  sewer flushing  has been tested in
selected areas (WPCF, 1989).

Storage

CSO  discharges occur when the flow  in  a combined
system exceeds the capacity of the sewer system or the
treatment plant. Storing all or  a portion of the CSO
discharges  for  treatment during dry weather  can
effectively reduce these overflows. Storage techniques
include in-line and off-line  storage.

In-Line Storage. In-line storage uses existing capacity
in major combined sewer  trunk lines or interceptors to
store combined flows. During  storms,  regulators are
used  to cause flow to back up in the system allowing it
to be stored in the system. While not  all  flow can be
stored in the sewer system, this practice can reduce
overflow volumes during  large storms and eliminate
overflow volumes during small  storms. After a storm,
stored  flow  proceeds  to  the  treatment  plant  for
treatment. The overall pollutant  removal in this practice
depends on the level of storage space  available in the
existing  system. Care must be taken  to  ensure that
flows do not back up onto streets or into homes.

Off-Line   Storage.  Off-line  storage  consists  of
constructed  near-surface  or deep  tunnel  detention
facilities. Near-surface facilities usually consist of
concrete tanks or, in some cases, large conduits which
also convey flow to a treatment facility.  Tunnels can
provide large storage volumes with relatively  minimal
disturbance to the ground surface, which  can  be very
beneficial in congested urban areas.  Overflows are
directed to the storage facility, held during the storm,
and  pumped to  the POTW  after  the  storm, thus
reducing  the overflow  quantity  and frequency. The
overall pollutant removal  in this practice  depends on
the design capacity of the storage facility and the
percentage of overflows that can be stored.

Flow Balance  Method.  The in-receiving water flow
balance method involves  using floating pontoons and
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 flexible curtains to create an in-receiving water storage
 facility. CSO flows fill the  facility  by displacing the
 receiving  water that  normally  occupies the storage
 facility. The  CSO  flows are  then pumped  to the
 collection  system following  a storm.  The technology
 has been used for CSO control in Brooklyn, New York.
 This alternative involves permanently  installing the
 floating pontoons in the receiving water near the CSO
 outlets. The  feasibility of this  technology, therefore,
 depends in part on  whether the storage facility would
 have a significant impact on the aesthetic value of the
 surrounding area, and whether the structure would be
 a hindrance to navigation. Other site-specific concerns
 include the availability of volume due to tidal variations
 in  coastal waters and the  need for  protection from
 damage due to high  winds or wave action.

 Physical Treatment

 Most of the urban runoff BMPs previously discussed
 employ physical processes to reduce pollution. Physical
 treatment practices can also be used to reduce pollutant
 discharges from CSOs. The practices discussed in this
 section  include  bar  racks  and  screens and  swirl
 concentrators/vortex solids separators.

 Bar  Racks  and  Screens.  These  practices use
 screening technologies to reduce the flow of solids in
 combined  systems. They  are typically  used  as a
 preliminary treatment  step  to  remove  floatables
 upstream of other processes. Different screens have
 different size  openings to  provide  various levels  of
 solids removal.  Bar racks have the largest openings
 (typically 1 inch or more)  and microstrainers have the
 smallest openings (typically as small as 15 microns).
 All  these   practices  require  periodic  and  regular
 cleaning  to  prevent  the  accumulation  of  solids.
 Typically only the smaller screens  provide significant
 pollutant  removal.  Screens  are most effective  at
 removing floatables  and,  depending on screen size,
 can remove suspended solids and  can provide some
 BOD removal.

 Swirl Concentrators/Vortex Solids Separators. These
 technologies are designed to provide flow regulation
 and remove solids from combined flow by forcing flow
 into a vortex path, so that solids and nonsolids can be
 separated. The resulting underflow containing separated
 solids can  then be  conveyed to a treatment facility.
 One advantage of these structures is that they have no
 moving  parts and  thus  require less  maintenance
 than  other structures. The  effectiveness of  swirl
 concentrators and vortex solids separators depends on
 the settling characteristics  of the  CSO solids, the
 amount of turbulence created in the structure, and the
flow rate. Data have shown  that these practices can
 provide  up  to  60-percent removal of solids and BOD,
with the greatest removal occurring during the first
flush washoff (WPCF, 1989). They are, however, most
 effective in removing larger solids; their performance is
 highly dependent on the  influent solids particle size
 distribution and specific gravity.

 Dissolved Air  Floatation. Dissolved  air floatation
 (DAF) removes solids from wastewater by introducing
 fine  air  bubbles  which  attach to  solid  particles
 suspended in the liquid, causing the solids to float to
 the surface where they  can be skimmed off. While this
 technology has been tested in CSO applications, it has
 not been widely applied. Because of its relatively high
 overflow rate and short detention time, DAF does not
 require   as   large   a   facility   as  conventional
 sedimentation. Oil  and  grease are  also more  readily
 removed by dissolved air floatation. The high operating
 costs for DAF are due to large energy demand; skilled
 operators are required for its operation.

 Fine Screens  and Microstrainers.  These devices
 remove solids  through  capture on screen media. The
 most common fine-screening devices include  rotary
 drum and rotary disk  devices.  In  the rotary  drum
 screen, media is mounted on  a rotating drum. Flow
 enters the end of the drum, and passes out through the
 filter  media.  Drum   rotational   speed   is  usually
 adjustable. Solids retained on the inside of the drum
 are backwashed to a  collection  trough. Filter  media
 aperture size typically ranges from 15  to 600 microns.
 The rotary  disk  screen  has  the  screening  media
 mounted on  a circular  frame placed perpendicular to
 the flow. Flow passes through  the bottom  half of the
 rotating disk, which is submerged. Solids retained on
 the disk are directed to a discharge launder  using
 spray water.

 One form of static screens features wedge-shaped steel
 bars,  with  the flat part  of the wedge facing the flow.
 These wedge-wire screens typically  have openings
 ranging from 0.01  to 0.05 in. These screens require
 daily maintenance to prevent clogging (Metcalf & Eddy,
 Inc., 1991). Screens are subject to blinding from grease
 and first-flush solids loads; a high-pressure  backwash,
 as  well as the collection and conveyance of backwash
 solids, are typically  required.  Effective cleaning of
 screens after storm events using  high pressure steam
 or  cleaning  agents is  typically  required to maintain
 performance. Removal efficiencies can be increased by
 decreasing media aperture size, but  smaller apertures
 are  more  likely  to blind. Coarse  screening  and
 disinfection facilities are often provided in conjunction
 with microstrainers.

 Filtration.  Dual-media  high-rate  filtration  has  been
 piloted for treatment of  CSO flows using a two-layer
 bed, consisting of coarse anthracite particles on top of
 less coarse  sand.  After backwash, the less dense
anthracite remains on top of the sand. Filtration  rates
of 8 gal/f^/min or more result in substantially smaller
area  requirements  compared  with  sedimentation.
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Demonstration test  systems include pretreatment by
microstrainers.  The  use  of  chemical  coagulants
improves performance considerably. A disadvantage to
filtration is the filters'  tendency to clog during use in
treating wastewater, thus limiting  hydraulic capacity
and effectiveness of solids removal. Filtration is more
appropriately applied  after  sedimentation  or  fine
screening to provide pretreatment. While operation can
be automated, filtration tends to be O&M intensive.

Chemical Precipitation

Chemical precipitation facilities store and use polymer,
alum, or ferric chloride to cause solids to precipitate.
Chemical  precipitation  can  increase  the  pollution
removal  that  generally  occurs from  other settling
practices, thereby allowing  for  the design of smaller
sedimentation tanks. Chemical precipitation generates
more sludge than other settling techniques. Pollutant
removal depends on the types of chemicals used and
the characteristics of the combined flow.  Removal  rates
for these practices are up to 70 percent for BOD and
85  percent for  suspended  solids. Because  CSO
treatment facilities are  intermittently operated, however,
sludge buildup and handling can  become a major
problem.

Biological Treatment
While biological treatment processes have the potential
to provide a high quality effluent,  disadvantages of
biological treatment  of CSOs include:
• The biomass used to break down the organic material
  and assimilate nutrients  in the  combined sewage
  must be kept alive during dry weather, which can be
  difficult  except at   an  existing  treatment plant;
  biological  processes  are subject to  upset when
  exposed to intermittent and highly variable loading
  conditions.
• The land requirements for these types of processes
  can preclude their use in  urban areas.
• Operation and  maintenance can be  costly and the
  process requires highly skilled operators.

Some biological treatment technologies are utilized in
CSO control as elements of a wastewater treatment
plant.  Pump-back flows from CSO  storage  facilities
commonly receive secondary treatment at the treatment
plant, once wet-weather flows have subsided.  In a
treatment plant that has maximized the  wet-weather
flows it accepts, flows are sometimes split, with only a
portion of the primary treated flows receiving secondary
treatment; to avoid  process upset. The split flows are
blended and disinfected for discharge.

Disinfection

Because pathogens are the primary pollutant of concern
in CSO control, practices focusing on disinfection are
commonly used.

Chlorination.  Combined flows can be  treated with
dissolved or gaseous chlorine to reduce the level of
pathogens in the flow. Chlorination is typically used in
conjunction with upstream solids removal.  Chlorination,
however,  is not effective at  addressing  aesthetic or
other water quality  impacts  of CSOs.  Dissolved
chlorine  (hypochlorite) is currently  more commonly
used than gaseous  chlorine because the equipment is
more reliable and storage of the chemicals is  safer.
Dechlorination  might be necessary to minimize the
adverse   effects   of   chlorine  on  aquatic   life.
Effectiveness of disinfection depends on the amount of
chlorine  used  and the  contact time between  the
chlorine  and the  wastewater. With sufficient dosage
and  mixing,  close to  100-percent destruction  of
pathogens is possible. These facilities require regular
inspection and maintenance.

UV Radiation. Introduction of  ultraviolet radiation to
combined   wastewater  is   designed   to   provide
disinfection without the addition of harmful chemicals.
This practice uses an ultraviolet lamp submerged in a
baffled channel located  downstream of  an effective
solids removal  process. The  effectiveness of  this
practice  depends on the lamp intensity, the contact
time  between  the  lamp and  the  wastewater,  the
distance  between the wastewater and the lamp, and
the  level of solids  in the wastewater. This system
provides disinfection only and does not contribute to
removing other pollutants. The high amount of solids in
CSO flows  limits the performance of  UV  radiation
unless the solids can first be reduced.
An overview of urban runoff and CSO BMPs is given to
help develop a list of BMPs to be screened.  As noted
earlier,  many  references  also can  be  used  (see
Appendix B). After the BMPs have been screened, BMP
selection is the next step of the planning approach.
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                                       Case Study:
                                  City of Austin, Texas,
                            Local Watersheds Ordinances
 Austin, a highly urbanized city bisected by the Colorado River, contains a number of high quality lakes,
 aquifers, and streams. The major water resources in the area include three lakes—Lake Travis, Lake
 Austin, and Town Lake—which form a major drinking-water reservoir acting as the main water supply
 for the city; Edwards Aquifer and Barton Springs are the area's other major water resources. These
 water resources are potentially threatened by urban runoff pollution from urbanized areas; Town Lake
 already is affected  significantly. To reduce and prevent urban  runoff pollution problems in these
 resources, Austin has developed and passed three major watershed ordinances:
 • The Comprehensive Watersheds Ordinance, 1986
 • The Urban Watersheds Ordinance, 1991

 • The Barton Springs Ordinance, 1992

 The primary goal of these ordinances is to protect the water resources of the  Austin  area from
 degradation from nonpoint source pollution. Other goals include preventing the loss  of recharge to the
 Edwards Aquifer, preventing adverse impacts from wastewater discharges, and protecting the natural
 and traditional character of the water resources in the Austin area. In addition, the city has implemented
 other ordinances that control NPS pollution.

 Water pollution problems in the Austin area have been extensively studied since the mid-1970s. In 1981,
 the city participated in NURP and began implementing and monitoring the effectiveness of urban runoff
 structural controls. The city has been a leader in developing and implementing NPS regulatory controls. The
 city's first NPS  control ordinance, the Lake Austin Watershed Ordinance in 1978, was followed by other
 watershed ordinances in 1981 and 1984 designed to protect additional sensitive watersheds and upgrade
 the level of protection. The experience and data gathered as a result of these ordinances led the city to
 propose and adopt a more complete set of protections for water resources as described in this summary.

 The Comprehensive Watersheds Ordinance

 The Comprehensive Watersheds Ordinance (CWO) is directed at preventing urban runoff pollution by
 placing requirements on proposed new developments within a 700-square-mile area of the city and its
 extraterritorial jurisdiction. It was developed in  1986 by a task force, appointed by the city council, with
 representatives from environmental groups, citizens, developers, and a council-appointed environmental
 board. The ordinance includes requirements for limiting impervious cover, using water quality buffer
 zones,  protecting critical  environmental  features,  limiting  the  disturbance of  natural  streams,
 implementing erosion control practices, constructing sedimentation and filtration basins, and restricting
 onsite wastewater disposal. The ordinance divides the city into four different watershed categories that
 each allow for different levels of development  intensity: urban,  suburban, water supply suburban, and
 water supply rural. While urban watersheds were not originally covered by the CWO, they are addressed
 in the Urban Watersheds Ordinance which is described later. Requirements  for all the applicable
 watershed categories are shown in Table 7-3.

 The  waterways located in each watershed category are classified as minor,  intermediate,  or major
 depending on the total drainage area contributory to the  waterway (see Table 7-3). Each waterway
 classification  has  an associated critical  water quality (WQ)  zone which encompasses the  100-year
 floodplain boundary  and is located 50  to 100  feet from minor  waterways,  100 to 200  feet from
 intermediate waterways, and 200 to 400 feet from major waterways. No development is allowed in this
critical WQ zone. Each waterway type also has an associated water quality buffer zone that begins at
the end of the  critical WQ zone and extends upland for a defined distance as shown in Table 7-3.
 Development in this zone is restricted by limits on the allowed percent imperviousness of the site. Areas
outside the WQ buffer zone are considered upland areas and have less stringent percent imperviousness
                                            130

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Table 7-3. Maximum Development Intensity
Waterways
Watershed Inter-
Category Minor mediate
Suburban


Drainage area: 320 ac 640 ac
Critical WQ zone: 100 ft 200 ft
WQ buffer zone: None 100 ft

Water Supply Suburban — Class 1


Drainage area: 128 ac 320 ac
Critical WQ zone: 100 ft 200 ft
WQ buffer zone: 100 ft 200 ft



Water Supply Suburban — Class II


Drainage area: 128 ac 320 ac
Critical WQ zone: 100 ft 200 ft
WQ buffer zone: 100 ft 200 ft



Water Supply Suburban— Class III


Drainage area: 320 ac 640 ac
Critical WQ zone: 100 ft 200 ft
WQ buffer zone: 100 ft 200 ft

Water Supply Rural

' Drainage area: 64 ac 20 ac
Critical WQ zone: 100 ft . 200 ft
WQ buffer zone: 100 ft 200 ft








a Net site area.

Major



1,280ac
400ft
150ft




640 ac
400ft
300ft






640 ac
400ft
300ft






1,280ac
400ft
300ft



640 ac
400ft
300ft









Except in Lake Austin/Lake Travis, where filtration
0 Only at major intersections.

Development Limits
Water Quality
Buffer Zone



30-percent
impervious cover





18-percent
impervious
cover; no
development
over recharge
zone



30-percent
impervious
cover; no
development
over recharge
zone



30-percent
impervious cover




One unit per 3
acres; no
development
over recharge
zone







is required.


Area Type



Residential:
Duplex:
Multifamily:
Commercial:



Residential:
Multifamily:
Commercial:






Residential:
Multifamily:
Commercial:






Single-family:
Duplex:
Multifamily:
Commercial:


Single-family:
Cluster:





Multifamily:
Commercial:
Planned:
Retail:



Uplands
Zone9 Transfer

% Impervious
Cover •
50 60
55 60
60 70
80 90

% Impervious
Cover
30 40
40 55
40 55




% Impervious
Cover
40 55
60 65
60 70




% Impervious
Cover
45 50
55 60
60 65
65 70

Unlts/ac
0.5 1.0
1.0 2.0



% Impervious
Cover
20 25
20 25
50 50
50-60° 60-70



Acceptable
Cfviiftfiiral
oiruciurai
Pollution
Controls



Sedimentation
Sedimentation
Filtration
Filtration



Filtration
Filtration
Filtration






Filtration
Filtration
Filtration






Filtration
Filtration
Filtration
Filtration


40% buffer"





40% buffer
40% buffer
40% buffer
Filtration



131

-------
  restrictions. In this zone, the restrictions are tied to the type of development proposed for the site as
  shown in Table 7-3. Some development restrictions  can be reduced if the developer transfers land
  located in the watershed to the city. In this way, development density can be increased by the developer
  in exchange for an increase in publicly held lands. For example, a multifamily development in suburban
  Class I water supply watershed is restricted to 40-percent impervious unless the developer is able to
  use development rights transfers (see Table 7-3). In this case, the development can reach 55-percent
  impervious and still meet the requirements of the ordinance.

  In addition to the restrictions on site percent imperviousness,  developments in these watersheds are
  required to incorporate structural control practices. The acceptable control practices are sedimentation
  basins, filtration basins, and vegetative buffers as outlined in Table 7-3. Basins must be designed to
  capture, isolate, and hold at least the first one-half inch of runoff from contributing drainage areas. Also,
  nonstructural requirements serve to prevent pollution. These include limitations on the depth of cuts and
 fills, limitations on construction on steep slopes  (greater than 15 percent), and limitations on the
 disturbance of natural streams including  restrictions on the number of stream crossings. Temporary
 erosion controls, such as silt fences and rock berms, are required during construction.

 In Austin, proposed new development plans are reviewed by  a separate environmental review staff,
 autonomous from other departments. This allows for  a focused review that includes field surveys of
 projects in sensitive areas.  Once the plans are approved, city inspectors monitor construction for
 compliance with the approved plans. Approximately 50 percent of  the financing for  reviews and
 inspections required by this ordinance comes from development permit fees. The fees vary depending
 on the development size and  are higher in sensitive watersheds because of the  increased review
 requirements. The rest of the expenses are covered through a drainage utility fund which consists of
 monthly service charges to the residents in the utility service area.

 Since these requirements apply to new developments, the CWO is designed to prevent or reduce future
 increases  in pollutant load to the  target water bodies. The ordinance can be applied  to a variety of
 watershed characteristics and water resource types.

 Given the short time this ordinance has existed and its focus on prevention, assessing its effectiveness
 is difficult. These control measures, however, have been shown to reduce urban runoff pollution on a
 nationwide and a local level. The city's analysis of its nonpoint  source  monitoring program, completed
 in 1990, showed that pollutant loads increase with increased impervious cover. Figure 7-14, based on
 that 1990 report, compares total suspended solid loads from land with various levels of development as
 measured  by percent impervious  cover. This type of data was used to define the impervious land
 limitations  in the ordinance.

 Urban Watersheds Ordinance

 In 1991, the city council approved task force recommendatiohs to include urban area watersheds among
 those covered by development ordinances. This ordinance, created in response to increased pollution
 in Town Lake due to urban runoff discharges, focuses on the urban watersheds not previously covered
 by the CWO. It requires the implementation of structural controls in new developments undergoing site
 plan review. All new residential, multifamily, commercial, industrial, and civic development  in the urban
 watersheds are required to construct water quality basins (either sedimentation or filtration basins) or
 provide a cash payment to the city  for use  in  an Urban Watersheds  Structural Control Fund. Structural
 controls must be used  to capture the first  one-half inch of runoff from all contributing areas. The
 Watersheds Structural Control Fund is used to retrofit and maintain structural controls where required
 in the urban watersheds. In addition to this requirement, new developments in the urban watersheds are
 required to provide for removal of floating materials from storm water runoff through the use of oil/water
 separators or other practices. Redevelopment projects in the urban watersheds are also included in this
 ordinance,  where structural  controls and the  removal  of floatable materials are  required. For
 redevelopment projects, the city has, developed a Cost Recovery Program Fund to provide 75 percent
of the cost of structural controls. These funds will be allocated through the drainage utility fund.
                                             132

-------
                                                  n TSS Loading, nonrecnarge zone
                                                  O TSS Loading, recharge zone
                                                            II      I
              1,200
              1,000
               800
            -„ 600
               400
               200
                   0     10     20    30    40    50    60    70     80     90    100
                                      Percent Impervious Cover

Figure 7-14.  Total suspended solids loading vs. percent impervious cover.

In urban watersheds, the critical WQ zone is the boundary of the 100-year floodplain and is generally
located  50 to 400 feet from the waterway. As with the Comprehensive Watersheds  Ordinance, no
development is allowed in the critical WQ zone.
Since this ordinance was passed only recently, there are no data concerning its effectiveness. Like the
CWO, however, it focuses on using proven structural and nonstructural control measures that the city
believes will effectively prevent urban runoff pollution.

Other  Nonpoint Source Control Programs
In addition to the CWO and the Urban  Watersheds Ordinance, Austin has developed other ordinances
designed to reduce nonpoint source pollution from new developments and  redevelopments. One of
these, the Barton Springs Zone Ordinance, provides special protection to watersheds contributing to
Barton Springs, a widely visited and used natural spring bathing area in Austin. This ordinance, created
to be a nondegradation ordinance with specific performance  requirements, includes definitions of
waterways and development limits similar to those specified  in the CWO.  Only one- or two-family
residential development with a  density  of 1 unit per 3 acres is allowed in the Barton Springs watershed
transition zone, which extends up to 300 feet from the water body. In addition,  new developments in the
Barton Springs watershed must comply with the following requirements (see Table 7-4): reduce pollutant
concentrations compared with  the  undeveloped conditions and discharge no greater than a specific
maximum pollutant concentration after development. The city measures these requirements quarterly on
each development through a developer-funded monitoring program.

Additional NFS control programs in Austin include:
• Land Development Code: Enforces  landscaping regulations and protects trees and natural areas in
  "the city.
• Underground Storage Tank  Program: Develops  guidelines for underground storage of hazardous
  materials, permitting and inspection of these underground storage tanks, and investigation of problems
  and response to emergency situations.
• Water Quality Retrofit Program:  Involves  engineering and building, with private sector participants,
  permanent controls for already  developed  areas and are producing storm water  runoff pollution
  problems for the city's key receiving waters.
                                             133

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                          Table 7-4.  Barton Creek Development Requirements
                          Pollutant
Percent Reduction
from Background
Maximum Discharge
Concentration, mg/L
                          Total suspended solids

                          Total phosphorus

                          Total nitrogen

                          Total organic carbon
     60%

     15%

     15%

     50%
     144

       0.11

       0.95

      14
        Water Quality Monitoring Program: Monitors and characterizes pollutants from various land uses and
        structural controls, monitors surface and ground-water quality, and develops water quality models and
        data bases; also conducts specific studies on known nonpoint source problems.
        Household Chemical Collection Program: Provides for safe disposal of hazardous materials and other
        wastes generated from  household use; conducted for the past 6 years, this  program is currently
        located at a permanent site where collection events occur each year.
        Storm Sewer Discharge Permit Program: Involves permitting and regular inspection of industrial and
        commercial discharges to storm sewers and water courses.
        Emergency and Pollution Incident Response Program: Involves responding to emergency spills,
        general water pollution incidents, and citizen complaints related to water quality.
        Street Cleaning and Litter Collection Program: Provides regular street cleaning—nightly in the central
        business district, monthly on other major roads, and bimonthly in residential neighborhoods.
        Integrated Pest Management Program: Encourages application of the most environmentally safe
        pesticide techniques practicable for pest management in municipal operations.
References
When  an NTIS  number is cited in  a reference, that
document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650
City of Austin,  TX. 1990.  Removal efficiencies of
  stormwater   control   structures.   Environmental
  Resource Management Division, Environmental and
  Conservation Services Department.
Galll, J. 1990. Peat-sand filters: a proposed stormwater
  management practice for urbanized areas. Department
  of Environmental Programs, Metropolitan Washington
  Council of Governments. Washington, DC.
Horner, R. 1988. Biofiltration systems for urban runoff
  water quality control.  Washington State Department
  of Ecology. Seattle, WA.

Undsey, G., L Roberts, and W. Page. 1991. Stormwater
  management  infiltration  practices  in  Maryland:  a
  second   survey.  Maryland   Department  of  the
  Environment, Sediment and Stormwater Administration.
  Baltimore, MD.
      Livingston, E., E. McCarron, J. Cox, and P. Sanzone.
        1988. The Florida development manual: a guide to
        sound  land  and  water   management.   Florida
        Department of Environmental Regulation. Stormwater/
        Nonpoint Source Management Section.

      MD WRA. 1986. Maryland Water  Resources Authority.
        Minimum water quality and planning guidelines for
        infiltration practices. Maryland Department of Natural
        Resources.

      Metcalf & Eddy, Inc. 1991. Wastewater engineering:
        treatment, disposal, reuse. New York, NY: McGraw-
        Hill, Inc.

      MPCA.  1989.   Minnesota  Pollution  Control  Agency.
        Protecting water quality in urban areas. St. Paul, MN.

      Moffa,  P.  1990. Control and treatment of combined
        sewer overflows. New  York,  NY:  Van  Nostrand
        Reinhold.

      Pitt, R. 1989. Source Loading and Management Model:
        an urban nonpoint source quality model—volume  I:
        model development  and  summary.  University  of
        Alabama, Birmingham.
                                                 134

-------
RIDEM.   1989.   Rhode   Island  Department  of
  Environmental  Management.  Artificial  wetlands  for
  stormwater treatment: processes and designs. Rhode
  Island Nonpoint Source Management  Program.

Roesner, L.A., B. Urbonas,  and M.B.  Sonnen. 1988.
  Design of urban runoff quality controls: proceedings
  of an engineering foundation  conference on current
  practice and design criteria for urban quality control.
  Potosi, MO. July. Published by the American Society
  of Civil Engineers, New York,  NY.

Schueler, T. 1987. Controlling urban runoff: a practical
  manual  for  planning and  designing urban BMPs.
  Metropolitan Washington Council of  Governments.

Shaver,  E.H.  1986.  Infiltration as  a stormwater
  management component. Maryland Department of
  the   Environment,  Sediment   and   Stormwater
  Administration.  Delaware  Department of  Natural
  Resources. Dover, DE.
Shaver, E.H. 1991. Sand filter design for water quality
  treatment. Delaware Department of Natural Resources.
  Dover, DE.
ULI.  1981. Urban Land  Institute.  Water  resource
  protection technology: a handbook  of measures to
  protect   water  resources in  land  development.
  Washington, DC.
U.S. EPA. 1973. U.S. Environmental Protection Agency.
  Water pollution and associated effects from  street
  salting.  EPA/R2-73/257 (NTIS PB-222795). U.S. EPA
  National Environmental Research Center.
U.S.  EPA. 1974a.  U.S.  Environmental  Protection
  Agency. Manual for deicing chemicals: storage  and
  handling. EPA/670/2-74/033 (NTIS PB-236152).
U.S.  EPA. 1974b.  U.S.  Environmental  Protection
  Agency. Manual for deicing  chemicals: application
  practices. EPA/670/2-74/045  (NTIS  PB-239694).
U.S.  EPA. 1974c.  U.S.  Environmental  Protection
  Agency.  Urban storm  water  management  and
  technology:  an  assessment.  EPA/670/2-74/040
  (NTIS PB-240687).
U.S. EPA. 1977.  U.S. Environmental Protection Agency.
   Urban  storm  water management  and technology:
   update and users' guide. EPA/600/8-77/014  (NTIS
   PB-275654). Washington, DC.
 U.S. EPA. 1979.  U.S. Environmental Protection Agency.
   Demonstration  of  nonpoint  pollution   abatement
   through  improved   street    cleaning   practices.
   EPA/600/2-79/161  (NTIS PB80-108988). U.S.  EPA
   Office of Research and Development.
U.S. EPA. 1983. U.S. Environmental Protection Agency.
  Results of the nationwide urban runoff program: vol.
  1-final report. (NTIS PB84-185552.) Water Planning
  Division. Washington, DC.
U.S. EPA. 1987. U.S. Environmental Protection Agency.
  Guide to nonpoint  source control. Office of Water.
  Washington, DC.
U.S.  EPA.  1991 a.  U.S.  Environmental  Protection
  Agency.  A  current  assessment of  urban best
  management practices: techniques for  reducing
  nonpoint source  pollution in the coastal zone. U.S.
  EPA Office of Wetlands, Oceans, and Watersheds.

U.S.  EPA.  1991b.  U.S.  Environmental  Protection
  Agency.    Postconstruction    stormwater   runoff
  treatment. Washington, DC.
U.S.  EPA  19923.  U.S.  Environmental  Protection
  Agency.  The  use  of  wetlands   for  controlling
  stormwater  pollution.   Region  V. Chicago,  IL.
  Distributed by the Terrene Institute. Washington, DC.

U.S.  EPA.  1992b.  U.S.  Environmental  Protection
  Agency.  Casco Bay  storm  water management
  project: Concord Gully, Frost Gully and Kelsey Brook
  watersheds. U.S. EPA Region I. Boston,  MA. January.

U.S.  EPA.  1992c.  U.S.  Environmental  Protection
  Agency. Decision-maker's storm water  handbook:  a
  primer. U.S. EPA Region V. Chicago, IL.

U.S.  EPA.  1993a.  U.S. Environmental  Protection
  Agency. Investigation of inappropriate pollutant entries
   into storm drainage systems. Storm and Combined
   Sewer Control Program.
U.S.  EPA.  1993b.  U.S. Environmental  Protection
   Agency. Guidance specifying  management measures
   for source of nonpoint pollution  in  coastal waters.
   EPA/840/B-92/002. U.S. EPA Office of Water.
WA DOE.  1991.  Washington  State  Department of
   Ecology. Storm  water management manual for the
   Puget Sound Basin.
Woodward-Clyde Consultants. 1989. Santa Clara Valley
   nonpoint source study. Santa Clara Valley Water District.
Woodward-Clyde Consultants.  1990.  Urban  targeting
   and BMP selection: an information and guidance
   manual for state NPS program staff engineers and
   managers. Final report.
 WPCF.  1989. Water Pollution Control Federation.
   Combined  sewer  overflow pollution  abatement:
   manual of practice FD-17.
                                                 135

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                                             Chapter 8
                             Select Best Management Practices
Urban runoff problems, because of their diverse nature,
need to be addressed through a combination of source
control, regulatory, and structural  BMPs. The selected
combination  needs to  reflect   the  program  goals
(Chapter 3) and the priorities set during the assessment
and  ranking  of existing problems  (Chapter  6). The
planning  approach in  this handbook recommends  a
two-step  process for  BMP selection.  This  chapter
covers the second part of the BMP selection process,
which uses the screened list of potentially applicable
BMPs  to  develop and select  the  BMPs  to be
implemented.
To select BMPs, the alternatives typically are developed
and compared to ensure that all options are considered
and that the best possible plan is selected based on a
predetermined set of selection criteria. While a specific
problem caused by a specific source, might not require
development  of alternative BMP  plans, for  most
programs which tend to deal with  multiple sources and
impacts,  it is wise to investigate alternatives before
selecting   a  final  set of  BMPs. This  chapter first
addresses development  of alternative plans and then
the selection of recommended BMPs. At the end of this
chapter, two separate case studies on methods of BMP
selection  are  presented.

Alternatives Development
Alternatives are developed using  the BMPs still under
consideration after the screening  process (Chapter 7).
The  alternatives can  include various combinations  of
source control, regulatory, and structural BMPs. Source
control and regulatory BMPs are often  implemented
across entire regions or  jurisdictions. Structural BMPs
can  be  directed  at  specific  pollutant  sources   or
implemented  across geographic areas, including both
structural  BMPs for  new  development  in currently
undeveloped  areas or for retrofit  in already developed
areas. To  address fully the urban runoff pollution
problems in an area, BMPs from all these categories
are often required.
Three  commonly  used  methods  for  developing
alternatives are discussed in this section. The first starts
with known urban runoff  problems and known pollutant
reductions desired. The second develops a range of
possible control levels for evaluation. The third involves
applying specific BMPs throughout a project area. Any
one or a combination of these methods can be used to
develop an urban runoff pollution prevention and control
plan.

In the first method, before developing the alternative
plans, the problems to be addressed and desired level
of control are decided. This information could  be
obtained  from the problem assessment and ranking
step  described in  Chapter  6.  Various types  or
combinations of practices are then developed to meet
the  desired  control  level  to  address  the  known
problems. For example, if a program goal is to reduce
fecal  coliform bacteria levels to below the criterion for
safe  consumption  so that  shellfishing beds can  be
opened, the level of control  needed must reduce the
bacteria counts to a known  level. Information on the
expected  bacteria loadings  from  various sources  is
needed. Combinations of BMPs can then be developed
to achieve the needed control level by  focusing on
BMPs that control  the various sources. Criteria  for
developing alternative BMPs to meet the  control level
can  include  cost, pollutant removal efficiency, site
characteristics, public acceptance, and others.

This alternative development method might lead to an
emphasis on structural controls because these BMPs
focus on  addressing pollution problems  from known
sources,  such as septic tanks, illicit cross-connections
in storm water drains, and others. It has the advantage,
however, of ensuring that known priority problems are
addressed by each alternative. While this method can
be used to develop alternatives for meeting either water
quality or technology-based goals,  it  is especially
applicable for meeting specific  water resource or
pollutant removal goals.

An example of this BMP selection method is shown in
Table 8-1. In this example, multiple pollution problems,
such  as agricultural runoff,  urban runoff, and  failed
onsite septic  systems, were  contributing to closed
shellfish  beds. Table  8-1  compares various  urban
runoff control practices for cost,  level of expected
improvement,  public agency support, and other factors
                                                 137

-------
 Table 8-1.  Sample BMP Selection (Metcalf & Eddy, Inc., 1989)
 BMP
                   Technical
                    Feasi-
            Monetary Factors
 Water    Public     Other
 Quality     and      NPS
Improve-   Agency  Control
billty    Capital   O&M   Funding    ment    Support   Efforts
                                                                               Demon-
                                                                               stration
                                                                                Value    Comments
 Urban Runoff

 Source controls

 Infiltration
Storage               +

Treatment             +


Land Disposal

Sawering              +

Alternative disposal      +


Nonstructural
         Low    Mod.


         Mod.    Low
                             High    High

                             High    High
                             High

                             High
                High

                Low
                                    Does not achieve WQ
                                    goals

                                    Soil and ground water
                                    might preclude its use
                                    Effective pollutant
                                    removal

                                    No bacteria removal

                                    High capital cost
                                    Environmental impacts
                                    High capital cost

                                    High capital cost
                                    Likely public opposition
Regulation and
enforcement
Tax Incentives
Local financing

Beneficiaries
financing
Public education

+ Low - - - - _ Extensive public support
required
- - + + - + No programs in place
— - + - - + Town funding not
available
- - + -,-+ Complete organizational
requirements
+ Mod. Low + + + + + Builds public awareness
and support
 + = Favorable or present
 — « Unfavorable or not present

 to   determine   the  best   mix  of   practices   for
 implementation.

 Based  on this review,  a combination of regulatory,
 educational, and structural runoff pollution prevention
 and control practices was  recommended:  enacting
 stricter local zoning and conservation bylaws oriented
 toward runoff pollution  prevention,  constructing  an
 infiltration  system  along a  stretch  of roadway with
 known  high  pollution  levels, conducting  a   public
 education  program, and improving  ongoing  water
 resource monitoring efforts.

 In the second method, alternatives representing a range
 of control  levels are developed.  For  example, three
 tevels of control could be formulated based on a range
 of pollutant removals (i.e., low, medium, and high). The
 low-level control alternative might consist of a minimum
 mbc of BMPs designed to address priority problems. The
 medium-level control alternative might  consist of  the
same practices as the low-level control alternative plus
additional  BMPs  designed   to  address additional
problems  or to  address more fully the same priority
problems.  The  high-level  control  alternative   might
                                   include  the practices of  the  medium-level control
                                   alternative  as  well  as  additional  practices.  Each
                                   alternative plan therefore contains a subset of the BMPs
                                   included in the next higher level  control alternative,
                                   allowing for a cost-effectiveness  comparison among
                                   various control levels.

                                   An example of this approach performed as part of the
                                   Santa  Clara  Valley   NPS  pollution  control   plan
                                   development  is  shown in Figure  8-1.  Three  BMP
                                   categories were considered: educational (E), regulatory
                                   (R), and public  agency  actions  (P). Within  each
                                   category, specific  BMP practices were identified (e.g.,
                                   E1, E2) and compared to evaluate the cost and benefit
                                   of each level. Some of the individual practices shown
                                   on  Figure 8-1 were considered but not included.  This
                                   approach is analogous to the screening step described
                                   in Chapter 7. The  complete process used in the Santa
                                   Clara Valley study is described in the case study at the
                                   end of this chapter.

                                   Another  example of this approach  which  includes
                                   structural controls is shown in Figure 8-2 (Pitt, 1989). In
                                   this  example,   10 different  urban  runoff   pollution
                                                    138

-------
Educational
control
measures

E1 , t
E2
E3
E4
E5
E6
E7
E8
E9
• E10
E11
E12
E13
E14
E15
E16
E17 '
E18
1













' \
k i






1 I






r 1

i






1







4
E19 '
, 	 Considered
E20 butnot
E21 included*
E22 j
                                              Regulatory
                                               control
                                              measures
R3
R4
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R16


R18
R19
R20
                                                rtt
                                                 i
        H  in
                                                   Considered
                                                     but not
                                                    included*
                                                       I
                                                       *
                           Practices in low-control alternative
                           Practices in medium-control alternative
                           Practices in high-control alternative
                            Removed during initial screening
Public
agency
actions



•ttt
P4 ' "
P5
P6
P7 J
P8
P9
P10
P11
P12
P13
P14
P15
P16
P17
P18
P19
P20
P21
P22
P23
P24
P25
P26
P27
P28
P29
P30
P31
P32
P33
P34


r




i r
















)
























r
t
Considered
but not
included*
1
Figure 8-1.  Example alternative development process (Woodward-Clyde Consultants, 1989).
prevention and control practices alternatives are plotted
to compare phosphorus reduction with annual cost. The
practices  analyzed include various combinations  of
street sweeping, catch basin cleaning, construction of
detention  basins,  and  implementation  of  infiltration
practices. Similar plots were also developed for solids
and lead removal. Based on this analysis, Program 8
was recommended, a combination of infiltration and wet
detention.

This second method is especially applicable for meeting
general goals that do  not include specific  pollutant
removal requirements. For example, if the goal is to
reduce nitrogen discharges to a coastal embayment by
the maximum  extent  practicable,  then  a  series  of
alternatives can be developed covering a,range  of
pollutant reduction levels and costs. These alternatives
then  can  be  compared  on  a  cost-benefit  and
affordability basis.
           The third method of developing alternatives begins with
           the screened list of appropriate control measures. Each
           BMP is then assessed for its ability to address the
           known  and anticipated  problems. As an  example,
           preference might generally be given to BMPs that:

           • Address more than one problem or lead to meeting
             more than one goal.
           • Have lower construction and operating costs.

           • Are  most effective at removing the pollutants  of
             concern.

           • Emphasize pollution prevention rather than treatment.

           • Are likely to address future problems.

           • Concentrate on addressing the priority problems.
           The assessment of individual BMPs results in alternatives
           based on implementing each BMP throughout the study
                                                   139

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              10—1
               8 —
               6 —
               2-
                                                                                           10
                                                                                           D
                                                                              7
                                                                              D
                               2
                               D
                               1
                               D
3
D
                                                          5
                                                          D
             4
             D
                                                                        6
                                                                        D
                                      8
                                      D
                                                                                     g
                                                                                     D
                                   "I	1	1	
                                    10                 20                 30
                                         Percent Reduction Compared to Current Program
                                               40
 Figure 8-2.  Phosphorus removal for candidate control programs (Pitt, 1989).
 area. The comparison of alternatives is then in effect a
 comparison of different BMPs. This approach yields
 useful data on systemwide implementation of particular
 BMPs. While  one type  of BMP might not address the
 range of urban runoff problems or goals in a study area,
 an urban runoff pollution problem might exist which a
 particular BMP is well suited to control.  In this case,
 implementation of that BMP  on a regional basis, with
 the BMPs strategically located by the municipality, can
 be more effective and more  easily controlled than
 requiring  each developer to  implement that BMP for
 individual developments.

 An example of this method of alternative  development
 Is the Henrico County,  Virginia, regional storm water
 detention program (George and Hartigan, 1992). Early
 in the process of developing a storm water management
 plan, it was decided that, given the conditions existing
 in the watershed, regional detention basins would be
 used to control  runoff pollution. Regional detention
 basins were chosen because they provide both flood
 and pollution  control, had fewer site restrictions than
 other pollution control structures, and can be designed
 to   accommodate   expected   new   developments.
 Therefore, the major remaining decision in the program
 was the number, location, and size of the detention
 basins.

 All the above methods lead to the development of
 alternative plans to address the urban runoff pollution
 problems of concern. While the actual contents of each
 alternative plan are site specific and depend on the type
of alternative evaluation to be conducted, some general
          guidelines for presenting the alternative plans can help
          in assessing them. Preliminary sketches, rough cost
          estimates,   expected   pollutant    removals,   and
          environmental  effects can  be  included  for  each
          alternative so comparisons can be made.

          BMP Selection Process

          After  the alternatives  have  been developed, they are
          compared using a decision  process  (Figure 8-3) that
          evaluates the relative  merits of each plan. Because of
          the complexity of urban runoff control  problems, a
          number of  factors must  be considered in  assessing
          alternative plans. These alternatives are represented in
          Figure 8-3 as  inputs  to the decision process, and
          include analysis tools, design conditions, and decision
          factors. The analysis tools are those used to assess and
          rank the existing  pollution problems (see Chapter 6).
          The design conditions are the set of conditions under
          which to compare the alternatives. The decision factors
          are the  criteria used to compare the alternatives. All
          these inputs are then used to evaluate the alte -natives
          using  one or more decision analysis methods. This
          section  first describes each input to the decision
          analysis, then describes the various decision analysis
          methodologies that can be used to select BMPs that will
          comprise the urban  runoff  pollution  prevention  and
          control plan.

          Analysis Tools

          These tools, described in  detail in Chapter 6,  can
          include watershed models, receiving-water models, and
                                                  140

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     Analysis Tools

     • Watershed models          ^ Source flows/loads
     • Water resource models 	*" Receiving water cone.
     • Ranking models       	*• Priority problems
                                           \
                                                 m
Design Conditions

• Wet-weather events
• PS/NPS flow/quality
• Receiving water flow/quality
      Decision Factors

     • Cost (capital, O&M)
     • Program goals
     • Environmental effects
     • Public acceptance
     • Others
Figure 8-3.  Conceptual diagram of BMP selection method.

ranking models. The numerous types of models range
from simple to complex, and selection of appropriate
models to use has been discussed. The analysis tools
are  used  to  project  future  conditions,  given  the
alternatives  being investigated. For example, the total
pollutant loads for each alternative can be calculated
(whether using a unit load method or complex models
such as SWMM), yielding one item of input information
as the alternatives are compared. Similarly, the impacts
to receiving  waters can  be assessed using these tools,
to compare these effects before making a decision.

In the Humber River drainage area in Toronto (Figure
8-2),  for example, SLAMM was used to analyze  10
different control programs (Pitt, 1989) for program cost
and pollutant removal.  The final decision was based
largely   on   the    cost-effectiveness   information
determined  for each of  the alternatives using this
analysis tool.

Design Conditions
One  major  consideration  in  BMP selection  is  to
determine  appropriate conditions  under  which  to
compare  the  alternatives. These  so-called  design
conditions are generally set up to reflect various future
conditions, including future no-action conditions which
reflect future expected  conditions with no new BMPs.
Some important design conditions to be  developed as
part of an urban runoff pollution prevention and control
plan include:
•  Population
•  Land use/expected development (i.e., buildout)
•  Point source/NPS flows/concentrations
•  Background receiving-water flows/concentrations
Decision Analysis
• Holistic
• Cost-benefit
• Matrix
• Decision factor
«Optimization
                                                                                        Recommended
                                                                                        BMP
                                                                                        plan
                                                 Each condition is defined for specific future planning
                                                 periods (e.g., 20 years).
                                                 Part  of the comparison  involves  the selection  of
                                                 worst-case  or  critical conditions. In  the  case  of  a
                                                 receiving water,  this condition could  be  a summer
                                                 low-flow period. In the case of urban runoff flow and
                                                 load  estimation,  it  often involves selection  of wet-
                                                 weather design conditions. These wet-weather conditions
                                                 are often in the form of design storms. For example,
                                                 runoff from a new development site might be required
                                                 to meet preexisting conditions up to a 25-year frequency
                                                 design storm. A state CSO policy might require control
                                                 up to a 1-year, 6-hour design storm. Two significant
                                                 concerns exist when developing wet-weather design
                                                 conditions. One is distinguishing between wet-weather
                                                 design  criteria used for pollution control and for flood
                                                 control.  The second is  the use of individual design
                                                 storms  versus multiple storms, continuous simulation,
                                                 or probabilistic methods.
                                                 Historically,  design  storms  have  been used to size
                                                 structures for flood control  purposes. These  facilities
                                                 were often sized to control  storms of 5-year,  10-year,
                                                 25-year, or  greater  return periods. In contrast,  BMPs
                                                 used for wet-weather pollution control can be sized for
                                                 much smaller storm events (e.g., 1-year storm or less),
                                                 because most rainfall events (over  90 percent) are
                                                 smaller than a 1-year storm. Thus, a BMP sized for a
                                                 1-year storm would control more than 90 percent of the
                                                 total runoff volume. Of course, many other BMP design
                                                 factors are important (e.g., retention time and peak flow
                                                 capacity), but design criteria  appropriate for pollution
                                                 control  should be kept in mind. This also points out the
                                                 need to consider multiple design conditions  for dual
                                                 purpose (water quality and flood control) BMPs.
                                                   141

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Individual design storms have been and still are often
used to size structural BMPs. They are also frequently
specified in various federal, state, and local regulations.
While use of a design storm is a simple, understandable
criterion, deciding on the size storm is less clear cut. A
review of wet-weather design conditions stresses the
benefits of using continuous or probabilistic simulation
rather  than relying on  a single design storm event
(Freedman and Marr, 1992). The increasing power and
speed of personal computers allows modeling of a long
time series  of   rainfall-runoff  conditions  (using  the
watershed models, and in some cases receiving water
models, described in Chapter 6) at a reasonable cost.
This method allows investigations of a large number of
storm events  and the ability to develop a frequency
distribution  of values  of  concern  (i.e.,  number  of
overflows, amount of pollutant load, or number of water
quality violations) for the range of rainfall conditions.

An example (Figure 8-4)  of  the use  of  continuous
simulation  (Freedman  and Marr, 1992) indicates a
frequency distribution of bacteria  concentrations with
and without CSOs at a particular location. Such results
frame the range of possible CSO control effects and
help determine appropriate control goals and level of
desired reduction for a range of conditions  rather than
for one event.

Decision Factors

An important step in BMP plan selection is to determine
the important  decision factors. The selection of these
factors is site  specific and needs to be determined  by
the program team based on the characteristics of the
watershed and the financial and personnel resources
available. Typical decision factors are discussed below.
Cost

One of the most important decision factors is the relative
cost of each alternative. In cost assessment, costs of
development  and  implementation for nonstructural
BMPs, as  well as of  construction and operation for
structural BMPs, need to be considered. The program
benefits  such  as those  associated  with  restored
resources also need to be considered. Costs should
generally reflect the life-cycle cost of an alternative over
the planning period and are usually easy to derive. The
cost benefits associated with the implementation of a
control plan,  however, are usually more difficult  to
determine.  For example, if an urban runoff control plan
is designed to reduce the discharge of fecal coliform to
a closed shellfish area, monetary benefits are derived
from  opening these  beds.  While  analysis of  these
benefits can be difficult, they  should  be included in
determining total program costs.

Meeting  Program Goals

Alternatives are also assessed  on  their ability to meet
program  goals, including the control of major sources
and effects  on priority watersheds. Since at this  stage
in a program, the  goals have  been reassessed and
expanded upon a  number of times, a  large number of
specific goals might exist, and  each alternative  might
not meet all the program goals.  Preference generally is
given to alternatives that address the most goals or the
most important goals.  Priority resources and pollution
sources should be the focus of the selected alternative.

Operability

The decision factors included here take into consideration
the reliability of structural controls, the reliance of the
alternative plan on existing structures,  and the number
                      160
                                       100           1,000          10,000
                                    Fecal Coliform Concentration, MPN/100 mL

Figure 8-4.  Example continuous simulation results (Freedman and Marr, 1992).
                          100,000
                                                   142

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of structures included in the alternative. Operability is
generally  a  measure  of  a  system's  complexity.
Complicated systems and plans  might be difficult or
expensive to implement and operate; these factors are,
therefore, taken into consideration in the BMP selection.
Typically, this decision factor favors source control and
regulatory practices  that  do  not have  the  level of
complexity and  possible  operational  problems of
structural controls.

Buildability

This decision factor is directed primarily at the selection
of  structural  BMPs.  Taking  into  consideration the
various aspects of construction, the criteria investigated
under this category include the site requirements, extent
of disruption, and degree of construction difficulty. When
relying  on  complex structural  controls,  difficulties
inherent in construction and future maintenance  might
need to  be overcome., While not a consideration  in
source control  and  regulatory control practice, this
factor can be very important for structural controls.

Environmental Effects
Implementing urban  runoff pollution control plans can
affect the environment both positively  and negatively.
The positive effects on  resources result  from the
removal of pollution  sources.  Resources that can be
positively affected include  water resources,  aquatic
animal and plant life, wildlife, wetlands,  and  many
others. The negative environmental effects, which can
include aesthetic problems, cross-media contamination,
the loss of useable land, wetlands impacts, and many
others, must also be considered in the assessment.
The importance of this decision factor is becoming more
widely recognized. There seems to be a shift away from
viewing urban  runoff control structures  only on their
pollution  control ability. Incorporating  structures into
new developments or retrofitting them in existing areas
can gain  wider acceptance  if  additional aesthetic
qualities are considered. For  example, unvegetated
aboveground  infiltration  basins   or  diy ponds  are
generally not attractive elements of the environment
and  could  serve  as   insect   breeding   grounds.
Natural-looking  wet  ponds  or  vegetated  wetlands,
however, can be incorporated into the environment and
even serve to  improve aesthetics. These  issues can
greatly affect public acceptance.

Institutional Factors

This decision factor relates to existing  governmental
structures,   legal   authority,  and   implementation
responsibilities. To implement alternatives, the logistical
resources must be in place, and the proper authority to
pass and enforce regulatory practices must exist. If the
proper authority does not exist, an analysis of attaining
it  must  be   undertaken.   In   addition  to  these
considerations, the team should investigate existing
urban runoff programs  in the community, region, or
state. Often, cost savings can be  realized and total
program efforts can be reduced by taking advantage of
material  and  data compiled during  these existing
programs.

Public Acceptance

In many instances, the public will be responsible for at
least a portion of the funding required to implement the
recommended plan. Public reaction to the urban runoff
control plan should, therefore, be assessed through the
use  of public meetings. Measuring  public acceptance
can  be difficult, but can  be important to the overall
success of a program,

Other Decision Factors

Additional  decision factors—such  as maintainability,
level of pollution control, or size requirements—can be
included in the assessment of alternative plans if they
are more important than those discussed above.
Once the final decision  factors have been chosen and
applied to  the alternative plans, the  plans can be
assessed through applying a decision analysis tool.
Methods  for  conducting this decision  analysis are
presented below.

Decision Analysis Methods
Assessing  alternatives takes into account a variety of
factors, both quantitative and qualitative.  The type of
assessment conducted  in  these  programs,  which
involves an integration and comparison of these factors,
is an example of multiattribute decision-making and can
be performed with various decision analysis methods.
The following decision analysis methods, which  are
listed in order from the most qualitative  to the most
quantitative, can be utilized:

• Holistic

« Cost-benefit ratios
• Matrix comparisons

• Decision  factor  analysis

• Optimization

Two additional BMP selection processes, which combine
aspects of a number of the above  approaches,  are
discussed in the case studies at the end of the chapter.

Holistic
This approach is qualitative and relies on certain basic
facts,  intuition, and  professional judgment.  One  key
deciding factor (e.g., cost) can guide the process. Given
                                                   143

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 the inherent complexity of assessing alternative urban
 runoff control plans and the large number of available
 inputs  to  the  decision,  this  approach  is  usually
 over-simplified. Selecting  an appropriate plan from the
 developed  alternatives  will   generally  require  an
 assessment of multiple factors and should be done in
 as quantitative a manner as is reasonably possible.

 Cost-Benefit Ratios

 The  relative  value of different alternatives  can be
 measured using cost-benefit ratios, such as cost per
 pound of pollutant removed or cost per day of effect on
 resources. This approach can be used as a tool to
 determine which  BMP  should  be  used  first.  For
 example, if it is determined that reducing solids using
 source control measures costs less  per pound than
 using a structural BMP, then source control measures
 should be utilized first Since the unit cost of source
 control measures increases with the amount of solids
 eliminated,  the  cost  per pound  of  solids  removed
 increases with the number of pounds  removed. The
 extent to which  source control measures should be
 used for pollutant removal is then given by the point at
 which the marginal cost-benefit ratio (i.e., change in
 cost/change in benefit) becomes larger than that of
 another alternative.
 Another advantage of the cost-benefit ratio approach is
 that it allows use of the knee-of-the curve methodology,
 which seeks to determine the  point in the cost-benefit
 curve where the marginal cost to achieve a marginal
 benefit becomes  significantly  higher. This factor is
 measured  by the marginal cost-benefit ratio defined
 above.   Figure   8-5   shows  an   example   of this
 methodology  where  the  cost-effectiveness   drops
 dramatically as practices are implemented to reduce
 lake standards exceedance to below 10 days per year.

 The cost-benefit ratio approach, however, is limited by the
 number of cost-benefit ratios that can be conveniently
 considered simultaneously. To represent the  different
 elements of a complex issue better, where some benefits
 might be counterbalanced by some detriments, multiple
 costs and benefits must be considered.

 Matrix Comparison

 Matrix comparison, a common decision-making method
 used in facilities planning and siting,  is suggested in
 EPA's Construction Grants guidelines  (see Table 8-2).
 Environmental impacts in Table 8-2 can be divided into
 short-term construction-related impacts and long-term
 operational impacts.  The matrix comparison approach
 is  also applicable to the assessment of  urban runoff
 control alternatives. This approach involves preparing a
 matrix that  compares alternatives against selected
 decision factors, both quantitative and qualitative. Where
 possible, numerical values  are given  to compare the
 alternatives, and, for qualitative factors, subjective
 comparisons are used (such as poor, fair, good, and
 excellent).

 An example of the matrix comparison approach for CSO
 abatement is shown in Table 8-3. In this example, three
 alternative control programs are  compared  for cost,
 conformance with objectives, operability, and buildability.
 While Alternative 1  provides  the  greatest  pollutant
 removal and reliability, it also has the highest cost. If
 cost is an important factor, Alternative 3 would be the
 selected  alternative,  since  it has the lowest present
 worth cost.  Alternative 2,  however,  provides  better
 reliability  than  Alternative  3  and  has equivalent
                        8
                        U)
                        I
                        °o
                        i£
                                           Annual days of water quality violation
                                                         vs.
                                                  Design storm facilities
                                         20    30
40
50
60
70
80
                                       Average Number of Days per Year
                                      Lake Standards Would Be Exceeded
Figure 8-5.  Example cost-benefit ratio curve (Moffa, 1990).
                                                  144

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Table 8-2.  Example Matrix Comparison (adapted from U.S. EPA, 1985)
                                                                    Alternatives
Type of Impact
                                        #3
#4
Monetary Cost, $
Capital cost

Annual O&M cost

.Cost per household unit

Environmental Impact
Cultural resources

Floodplains and wetlands

Agricultural lands

Coastal zones

Wild and scenic rivers

Fish and wildlife

Endangered species

Air quality

Water quality and uses

Noise, odor, aesthetics

Land use

Energy requirements

Recreational opportunity

Reliability

Implemcntability
o

•H-
Legend:
++  Significant beneficial impact
+   Minimal beneficial impact
o   No impact
-   Minimal adverse impact
••—  Significant adverse impact -•
cost-effectiveness in terms of present worth dollars per
gallon controlled. While this approach is useful, it can
be quite subjective and care and professional judgment
must be  taken in defining the appropriate decision
factors and applying the method.

Decision Factor Analysis
This is a matrix approach, which further quantifies the
decision factors by using weighting methods. In this
approach, quantitative factors are used to eliminate the
subjective   comparisons  required   in  other  matrix
approaches. These criteria should be:
1. Nondominant—no criterion should be dominant.  •
2. Complete—no  pertinent information  should be left
   out.
3. Scorable—criteria cannot be vague, since it must be
   weighted clearly.
4. Independent—criteria should not overlap each other.
              Weights are then generated for each decision factor.
              These weights must have  a  common  scale, and the
              relative importance of each factor to the decision should
              be  reflected  in  the weights. One  example of  this
              approach for site priority  setting was  described in
              Chapter 6.  A further example is the  BMP selection
              approach in the ME DEP case study at the end of this
              chapter. The  major  difference between  this approach
              and the matrix approach outlined above is that, in this
              approach, the decision  factors must be quantitative.
              Therefore, subjective comparison terms, such as good
              or fair, cannot be utilized. The decision factors must be
              able to be described by values that can be summed.
              Variations on this type of approach and various decision
              support software  can facilitate the conduct  of these
              analyses.

              Optimization

              Optimization,  a widely  used  method  of quantitative
              decision making, involves formulating a problem as the
                                                    145

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 Table 8-3.  Example CSO Abatement Alternative Matrix Comparison (Metcalf & Eddy, Inc., 1988)

                                                                         Alternatives

 Selection Criteria
                                                     #1
                                                                              #2
                                                                                                      #3
 Monetary Factors
 Capital cost

 Annual O&M cost

 Present worth (PW), 20 yr

 PW, S/gal

 Conformance with Objectives
 Control of major discharges

 Elimination of problem areas

 Impact of priority areas

 Operabillty
 Number of facilities

 Rolfability

 Level of O&M

 Reliance on existing facilities

 Impacts on downstream facilities

 Bulldabillty
 Site requirements

 Extent of disruption

 Dagrsa of difficulty

 Adaptability to phased Implementation

 Conformance with current plans
$176,000,000


$162,000,000

   $9.08



   Good

   Good

   Good


     0

   High

   Low

   Low

   Low


   Low

   High

   High

   Good

   Fair
$106,000,000

 $4,070,000

$139,000,000

   $7.77


   Good

    Fair

   Good


     3

  Medium

   High

   High

   High


   High

   Low

   High

   Fair

   Poor
$92,800,000

 $4,080,000

$126,000,000

   $7.77



   Good

    Fair

   Good


     3

    Low

    High

    High

    High


    High

    Low

    High

    Fair

   Poor
maximization (or minimization) of an objective function,
subject to a series of constraints. In linear optimization,
both the objective function and the constraints must be
linear functions of  the  decision variables.  Various
methods are available for finding the optimum set of
decision variables  and several software packages can
perform the analysis.  These methods are summarized
in basic textbooks  on  optimization (Monks, 1987).

For plan selection, the objective function can be cost or
a  more complicated  function of cost, benefits,  and
detriments. Examples of benefits that could be included
are gallons of discharge removed, pounds of pollutants
removed,  and  days  of  beach  closure  avoided. A
multifactor objective function can account for tradeoffs
among costs, benefits, and detriments by incorporating
relative weight for each factor:
where:
     F = objective function
     a) = weight and conversion factor
     yi = cost-benefit factor
         All terms in the above equations must have the same
         dimension   (e.g.,  dollars)  so  that   weights  also
         incorporate  a   conversion  factor.  The  optimization
         process  then  consists  of maximizing the  objective
         function, by optimally  selecting the  values  of the
         decision variables  on  which  the  different  factors
         depend.  Then,  each cost-benefit factor,  y|f  must  be
         expressed  linearly in  terms of each of the decision
         variables, X:
         where:
             by = a different weight or conversion factor

         This relationship is relatively easily established for cost
         (such  as Hfe-cycle cost),  but  more  difficult for other
         factors, such as pounds of pollutant removed or days of
         beach closure. For these types of factors, models need
         to  be applied with  different values  of the decision
         variable and straight-line fitted to the result. Constraints
         must also be established as  linear functions of the
         decision  variables.  Possible  constraints  are  the
         maximum number of excursions of standards per year
         or   the  maximum  amount  of  pollutant  reduction
                                                     146

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achievable  given background conditions.  Once the
objective function and constraints are defined, various
algorithms  and software packages are available to
determine  the  combination  of  decision  variables
maximizing the objective function.

A  major problem with  this  approach  is that many
relationships   pertaining  to  BMP  selections  are
nonlinear.  Qualitative  factors are  also difficult to
incorporate in  the process, especially in the  form of
linear functions  of the decision  variables.  Nonlinear
optimization,   while  accounting   for  the  nonlinear
dependence  of  various factors,  is  mathematically
complex. It also tends to suffer from the same types of
drawbacks  as linear programming because it is not
effective for problems that include qualitative factors.

Determination of Appropriate Decision
Analysis Approaches

Matrix   comparison  and  decision  factor  analysis
approaches are typically best suited to BMP selection.
Such approaches rely on the analytical tools available
to  analyze  the system and on the best professional
judgment of those assessing the alternatives. Given
specific problems that can be quantified, optimization
could be tried. Most BMP selection projects involving
urban runoff, however, would be too complex. If the
problems being addressed are simple, then the holistic
or  cost-benefit ratio  techniques can be utilized. These
simple, qualitative approaches can also be implemented
as first approximations for plan  assessments whose
final results  must  be  made using  more  complex
approaches.  In  summary,  an  appropriate  decision
analysis method or methods must be  selected  that
reflect:
• The  complexity of the problems and the  plans to
  address them.

• The  data needs of each method and the  ability to
  obtain the required data.

• The  financial and personnel resources available to
  conduct the assessment.

A matrix comparison or decision factor analysis most
likely would be involved.

Conclusions

The selection of BMPs to control urban runoff pollution
is difficult and can best be performed by undertaking a
systematic assessment process, aided by the use of
analytical tools and the selection of appropriate design
conditions  and  decision factors. Because  of the
qualitative nature  of  some inputs  to the  decision,
subjective comparisons among the alternative  plans
typically are  necessary. The process  outlined in this
chapter is a guide for  decision making,  but cannot
account for  all possible circumstances. Professional
judgment  and  care are needed  in determining the
methods   for  developing alternatives,  the  decision
factors to be employed, and  the decision  analysis
method to utilize. Once these choices have been  made
and the BMP plan has been selected, the urban  runoff
pollution prevention and control plan can be developed
in more detail so that it can be implemented.

The  following case studies provide examples of BMP
selection approaches used by the State of Maine for
runoff control in new developments and by the  Santa
Clara  Valley  Water Quality Control  Board in the
development and  implementation of  a major  runoff
pollution prevention and control plan.
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                                      Case Study:
                 Maine Department of Environmental Protection
                                BMP Selection Matrix
To address storm water and NPS pollution control in areas of new development, the Maine Department
of Environmental Protection (ME DEP) has developed a method to select BMPs. The method which is
presented in a state guidance document is based on the following information:

• Development land use type and size

• Receiving-water type (e.g., estuary, wetland, river, or stream)

• Watershed priority (either priority or non-priority)

• Erosion and sediment control target or level to achieve

• Storm water quality control target or level to achieve

• Erosion and sediment control options and treatment level codes

• Storm water quality control options and treatment level  codes
To implement the BMP selection method, ME DEP developed a series of eight matrices, two matrices
for each receiving water type  (i.e., estuary, wetland, river, and stream). One  matrix  is  applied to
development in designated priority watersheds and the other is applied to development in  nonpriority
watersheds. A priority watershed list has been developed by ME DEP based on environmental sensitivity,
local support for water quality, and importance of the watershed to the state. Example matrices for priority
and non-priority estuary watersheds are shown in Tables 8-4 and 8-5.
Each matrix has two major components, which are broken down by  land use type: an erosion and
sediment control level to  achieve and a storm water quality level to achieve. The level to achieve for a
given combination of land use  and receiving-water category is a relative, qualitative measure of the
impact of storm runoff pollution. It ranges from 1  to 5, with 1 being the lowest impact and 5 being the
greatest impact. For example, a multihousing development proposed for a priority estuary watershed is
given an erosion and sediment level  to achieve of 2 and a water quality level to achieve of 3.  By
comparison, a small residential  development in the same  priority watershed is given an erosion control
level to achieve of 1 and a water quality level to achieve of 1. In all cases, the levels to achieve  for
priority watersheds are greater than or equal to those for  nonpriority watersheds.

Each matrix also addresses the types of BMPs that can be implemented for pollution control. ME DEP
selected a number of BMPs and assigned each a treatment level code based on the expected level of
pollutant removal. The treatment level code is a relative,  qualitative  measure designed to indicate the
relative pollutant removal  expected from various BMPs. Treatment level  codes range from 1 to 3, with 1
providing the lowest level of control and 3 providing the greatest level of control. The BMPs and their
treatment level codes  are shown in Table 8-6. As indicated, various designs for  each BMP are given
different treatment level codes. For example, a 50-foot buffer is given a treatment level code of 1; a 125-foot
buffer is given a treatment level code of 2; and a 200-foot buffer is given a treatment level code of 3.

For a proposed development to be approved, the sum of treatment level codes for the proposed BMPs
must be greater than  or equal to the level to achieve.  For example, if a multihousing unit development
is proposed for a priority estuary (erosion level to achieve of 2 and water quality level to achieve of 3),
the developer could implement  erosion and sediment controls (treatment level 2) and a combination of
a swale (treatment level  1) and an infiltration system (treatment level 2). Additional combinations also
could be implemented as long as the total treatment level provided is greater than or equal  to the total
level to achieve. ME  DEP has  also recommended that at least one vegetative BMP be implemented
unless the site is already 100-percent impervious. The specified vegetative BMPs are buffers, grassed
swales with level spreaders, and swales.
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Table 8-4.  Priority Estuary Storm Water Control Matrix
Land Use Category
Low-density residential, >2 ac/lot
High-density residential, <2 ac/lot
Erosion and
Sediment
Level to
Achieve
1
2
Erosion and
Sediment Controls
Erosion and
sediment 1
Erosion and
sediment 2
Water Quality
Level to
Achieve
1
3
Storm Water Controls
Buffer 1
Buffer 1 or 2
Wet pond 2
Commercial, <1 ac disturbed


Commercial, 1-3 ac disturbed



Commercial, >3 ac disturbed
Intensive-use open space
(e.g., golf courses, nurseries)
Multihousing users
Erosion and
sediment 1

Erosion and
sediment 1


Erosion and
sediment 2
Erosion and
sediment 2
Erosion and
sediment 2
Infiltration 1 or 2
Created wetland 2

Buffer 1
Buffer 1 or 2
Infiltration 1
Swale 1

Buffer 1 or 2
Infiltration 1 or 2
Created wetland 2
Wet pond 2 or 3
Fertilizer control  1
Shallow impoundment 1

Buffer 1 or 2
Fertilizer control  1
Pesticide control 1
Created wetland 2 or 3
Wet pond 2 or 3

Buffer 1 or 2
Fertilizer control  1
Pesticide control 1
Created wetland 2
Wet pond 2
Infiltration 1 or 2
Industrial, <1
Industrial, 1-3
Industrial, >3
ac disturbed
ac disturbed
ac disturbed
1
1
2
Erosion and
sediment 1
Erosion and
sediment 1
Erosion and
sediment 2
1
2
5
Buffer 1
Swale 1
Buffer 1 or 2
Swale 1
Buffer 1 or 2
Swale 1
Created wetland 2
Wet pond 2 or 3


or 3
This BMP selection system is in its early stages of implementation. Its success will depend on the ability
to establish levels to achieve that adequately protect water bodies in new developments. It will also
depend on the ability of treatment level codes to  quantify the effectiveness of the identified  control
measures. Thus, the system is a technology-based approach for erosion and sediment control,  as well
as for storm water pollution  control.

Currently this method is outlined in a statewide guidance document and is not a regulatory requirement.
Municipal officials can incorporate this process at their discretion in subdivision regulations. This method
of BMP selection requires extensive upfront work to develop the matrices and BMP levels of treatment.
Once these are developed, however, this  method provides  a  simple and direct  technology-based
approach to BMP selection.  It has flexibility in terms of the range of BMPs that can be selected for given
types of proposed development and given site constraints.
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Table 8-5. Nonprlorlty Estuary Storm Water Control
Erosion and
Sediment
Level to
Land Use Category Achieve
Low-density residential, >2 ac/lot 1

High-density residential, <2 ac/lot 2

Commercial <1 ac disturbed 1

Commercial, 1-3 ac disturbed 1

Commercial, >3 ac disturbed 2



Intensive-use open space 2
(e.g., golf courses, nurseries)



Muilihouslng units 2

Industrial, <1 ac disturbed 1

Industrial, 1-3 ac disturbed 1

Industrial, >3 ac disturbed 2



Matrix


Erosion and
Sediment Controls
Erosion and
sediment 1
Erosion and
sediment 2
Erosion and
sediment 1
Erosion and
sediment 1
Erosion and
sediment 2


Erosion and
sediment 2



Erosion and
sediment 2
Erosion and
sediment 1
Erosion and
sediment 1
Erosion and
sediment 2




Water Quality
Level to
Achieve Storm Water Controls
1 Buffer 1

2 Buffer 1 or 2
Infiltration 1
1 Buffer 1

1 Buffer 1

2 Buffer 1 or 2
Infiltration 1
Swale 1
Shallow impoundment 1
3 Buffer 1 or 2
Infiltration 1 or 2
Fertilizer control 1
Created wetland 2
Wet pond 2
2 Buffer 1 or 2
Infiltration 1
1 Buffer 1
Swale 1
2 Buffer 1 or 2
Swale 1
4 Buffer 1 or 2
Swale 1 or 2
Created wetland 2 or 3
Wet pond 2 or 3
Table 8-6. Summary of BMP Treatment Level Codes
BMPs
Erosion and Sediment Control
One line of erosion control
Two lines of erosion control
Nongrassed Buffers
50ft
125ft
200ft
Infiltration Systems
Single system
Multiple systems
Wet Ponds
Single-pond system holding 2.5 in of runoff
Double-pond system each pond holding 2.5
Created Wetlands
Single created wetland
Two created wetlands
Other BMPs
Swales
Shallow impoundments
Street cleaning
Fertilizer application control
Pesticide use control
Grassed swales with level spreaders













in of runoff










Reverting land (i.e., allowing currently impervious land to be a
vegetative buffer)

Level of Treatment

1
2

1
2
3

1
2

2
3

2
3

1
1
1
1
1
1
1


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                                      Case Study:
                           Santa Clara Valley, California,
       Nonpoint Source Control Program BMP Screening Procedure


Background

In 1986, the San  Francisco Regional Water Quality Control Board developed a basin plan for San
Francisco Bay which involved regulatory activities to control point and nonpoint source discharges. The
basin plan was the driving force behind initiating the Santa Clara  Valley Nonpoint Source Control
Program. This program involves a number of local governments and county agencies and is designed
to address water quality problems in  Lower South San Francisco Bay. In developing the Santa Clara
Valley Nonpoint Source Plan, a 12-step process that closely follows the process outlined in this handbook
was used. The steps in this process are:

• Initiate program

• Determine existing conditions

• Conduct field monitoring

• Define program objectives
• Develop evaluation and planning criteria

• Compile inventory of candidate controls

• Apply criteria to screen candidates

• Apply professional judgment to select a practical set of controls

• Estimate overall program cost and  effectiveness
• Revise the previously defined control programs to balance cost, effectiveness, and other factors

• Describe the roles of various agencies

* Develop an implementation schedule
Development of the Santa Clara Valley Nonpoint Source Control Plan began in 1986 and has continued
through various stages to initial implementation and preliminary assessment of effectiveness.

Watershed Description

Santa Clara County, which incorporates the entire study area, is located at the southern end  of San
Francisco Bay (see Figure 8-6). The 690-square-mile watershed consists primarily of the relatively flat
Santa Clara Valley. Land use in the watershed is approximately 30 percent residential, 5 percent
industrial (predominantly light industry associated with high technology manufacturing), and 62 percent
open space. Three large cities—San Jose, Sunnyvale, and Santa Clara—account for the majority of
urban areas in the watershed.

Overview of Water Quality

To characterize existing water quality  in Lower South San Francisco Bay, a comprehensive monitoring
program was undertaken. This program included, hydrologic monitoring, wet- and dry-weather water
quality monitoring, sediment  monitoring, and biological monitoring. The monitoring was conducted
primarily to determine the levels of toxic pollutants, such as heavy metals and pesticides, as well as
nutrients and fecal coliform bacteria. Data obtained through this monitoring program were input to data
bases and used  for developing computer models. Watershed loads were estimated using the  Storm
Water Management Model (SWMM), calibrated to the observed data gathered in the monitoring program.
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                                                  Legend

                                                  —	Santa Clara County boundary
                                                          Approximate watershed and
                                                          study area boundary
Figure 8-6. Santa Clara Valley watershed.

The data were also used to compare the relative contributions of point (e.g., waste water treatment
plants) and nonpoint source pollution to the bay.

Water quality monitoring results indicated that heavy metal concentrations in receiving waters increase
during wet weather, because of contaminated runoff as well as resuspension of contaminated sediments.
The metals primarily detected were cadmium, chromium, copper, lead, nickel, and zinc. Copper was the
primary metal regularly detected at levels  greater than the EPA aquatic life criteria; these criteria were
exceeded only occasionally for cadmium,  lead, and zinc. Also,  during wet weather,  hydrocarbons and
pesticides were detected in approximately 25 percent of the ambient water samples collected,  while
none were detected during dry weather. The limited bacteria data gathered indicated increased levels
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(by a factor of about 10) of fecal coliform bacteria during wet weather as compared to dry-weather
conditions.
In comparing point and nonpoint source contributions to water quality problems in Lower South San
Francisco Bay, the monitoring results showed that point sources account for approximately 98 percent
of the nutrient load. Nonpoint sources, however, accounted for 60 to 80 percent of the load for metals
and about 98 percent of the total suspended solids yearly load.

Management Practice Screening
Because of the large size of the watershed and the variety of pollutants entering the Lower South San
Francisco Bay, the emphasis of the nonpoint source pollution control program was on pollution prevention
measures and nonstructural controls that could be implemented across municipal boundaries. Selection
of appropriate  pollution prevention measures and  controls was  accomplished  through a process
consisting of preliminary screening followed by final control measure selection (see Figure 8-7).
In order to screen the extensive list of potential pollution prevention and control practices, the program
team first listed important criteria for the selected measures. The criteria developed for this project were:
•  Pollutants controlled: Controls for metals, pesticides, oil and grease, bacteria, and sediments are
   emphasized.
•  Effectiveness: Each control measure should provide sufficient pollution control toward the overall
   program to warrant its inclusion.
•  Reliability/sustainability: Control measures should be effective over an extended time period and be
   able to be properly implemented over time.
•  Implementation cost: Control measures with low planning, design, land acquisition, construction, and
   equipment acquisition costs were emphasized.
•  Continuing costs: Emphasis was placed on control measures with low operation, maintenance, repair,
   support service, and equipment replacement costs.
•  Equitability: Controls were evaluated regarding  the degree to which costs and benefits would be
   equitably distributed among the participating agencies.
•  Universality: Controls were evaluated in terms of how universally they  would have to be applied to
   be effective.
•  Public  acceptability:  Control  measures were  assessed on  the expected  public response  to
   implementation.
•  Agency acceptability: Control measures were evaluated on  the expected response of agencies
   responsible for implementation.
• Relationship to regulatory requirements: Control measures were  evaluated on their consistency with
   existing and anticipated regulatory requirements.
• Risk/liability: Control measures were evaluated in terms of the risks or liabilities which could occur
   in implementation.
• Environmental implications: Control measures were evaluated regarding the positive and negative
   environmental impacts resulting from their use.
Once the control measure criteria were developed and agreed upon, the program team developed a
comprehensive list of potential measures for implementation. The inventory of potential measures was
developed through a review of technical literature  and other nonpoint  source  control programs. In
addition, technical and managerial personnel from other state agencies, county agencies, and city public
works and planning agencies were interviewed.
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154

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This review resulted in a list of more than 120 separate measures to be screened. This initial list was
to be comprehensive; no consideration was given to the applicability of the measures. Once the list had
been developed, however, obviously inappropriate measures were eliminated—primarily those designed
to address specific situations that did not exist in the watershed. This initial screening  reduced the list
of potential pollution prevention and control measures to 92.

This list of 92 measures was then assessed qualitatively using the criteria  developed earlier in  the
program. Each potential control measure was assigned a letter grade (A through F) for its ability to meet
the criteria. Measures receiving an A were viewed to meet all or  a large number of the  assessment
criteria, while those receiving an F were viewed to meet none or very few of the assessment criteria.
The control measures that fell into the category of F were immediately eliminated from further
consideration in the Santa Clara Valley watershed.
The final list of potential pollution prevention and control measures was then arranged into three groups
by grade, function, and implementation method as shown in Figure  8-7. The control measures  arranged
by  function included source controls, hydraulic controls, and  treatment-based  controls.  The control
measures arranged by implementation method included educational controls, regulatory controls, and
public agency actions. By arranging the controls in these various ways, the program team could select
control measures  that gave a good mix of type and implementation method.

Management Practice Selection
At this point, the assessment criteria used in the initial screening were applied to  each  potential control
measure to develop three alternative programs: Program I, the smallest scale program, was  designed
to be low cost and provided a minimal level of pollution control. Program III, the largest scale  program,
was designed to provide a high level of pollution control but had a high cost. Program II, designed to
represent a middle road between Programs I  and  III, was the program recommended in the report
because it was felt to provide the best cost-benefit of the three alternatives.
The recommended alternative included educational, regulatory, and  public works (structural) control
measures. Most  of these measures are  to be  implemented  across  the watershed, but  some
recommendations specific to known problems areas are also included.

Implementation
In order to efficiently implement the NPS control plan, the task force determined high-priority actions for
immediate implementation. The following actions are considered to  be high priority because they can be
implemented across the watershed.

• Conduct wet-weather  monitoring.
• Develop and implement a public information  program.
• Develop and begin implementation of illicit connection identification and removal.

• Conduct illegal  dumping monitoring program and provide training.

• Evaluate treatment based controls.
• Develop and begin implementation of areawide and community-specific storm water management
   program.
Still in the early stages of implementation, the program cannot yet be evaluated. Implementation of many
of  the above high-priority measures, however, is progressing. This case study shows  a qualitative
selection process that utilizes a set of screening and selection criteria to develop low, medium, and high
pollution prevention and control alternatives.
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References

When an  NTIS number is cited in a reference, that
document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650

Freedman, P.L., and Marr, J.K. 1992. Design conditions
  for wet weather controls. Proc. Water Environment
  Federation  Specialty Conference, Control of  Wet
  Weather Water Quality Problems. Indianapolis, IN.
  May 31-June 3.

George,  T.S.  and  J.P.  Hartigan.  1992.  Regional
  detention  planning  for stormwater  management:
  model for  NPDES  management programs. Proc.
  Water Environment Federation Specialty Conference,
  Control  of Wet Weather Water  Quality Problems.
  Indianapolis, IN. May 31-June 3.

Metcalf &  Eddy,  Inc. 1988. Lower Connecticut River
  phase   II   combined   sewer   overflow   study.
  Massachusetts Division of Water  Pollution Control.
Metcalf & Eddy,  Inc. 1989. Coastal  nonpoint source
  demonstration project: nonpoint source control for the
  watershed of Snell Creek—Westport, Massachusetts.
  Massachusetts Department of Environmental Protection.

Moffa,  P. 1990. Control and treatment  of combined
  sewer  overflows.  New  York, NY: Van  Nostrand
  Reinhold.

Monks, J.G. 1987. Operations management: theory and
  problems, 3rd ed. New York, NY: McGraw-Hill.

Pitt, Robert.  1989. Source  Loading and  Management
  Model:  an  urban nonpoint  source  water quality
  model—volume): model development and summary.
  University of Alabama, Birmingham.

U.S. EPA. 1985. U.S. Environmental Protection Agency.
  Construction grants 1985. EPA/430/09-84/004. U.S.
  EPA Office of Water. Washington, DC.

Woodward-Clyde  Consultants.  1989.  Santa  Clara
  Valley  nonpoint source study. Santa  Clara  Valley
  Water District.
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                                            Chapters
                                         Implement Plan
The final step in the planning process is to develop an
implementation plan for prevention and control of urban
runoff pollution. This plan sets forth the recommended
control program in  a form readily usable  by the team
charged with program implementation. The information
obtained through the earlier tasks of assessing existing
conditions,  collecting and  analyzing additional data,
identifying and assessing problems, and screening and
selecting BMPs  must be  clearly summarized as a
"roadmap" or work plan for future activities.

Contents of an  Urban Runoff Pollution
Prevention and Control Plan
The urban runoff pollution prevention and control plan
should contain the following information:
• Conceptual information on recommended BMPs
• Schedule of activities
• Responsibilities for BMP implementation
• Description of monitoring plan
• Summary of regulatory requirements
• Public involvement program
• Identification of funding sources/mechanisms
Each item is important to implementation of the plan and
is described in the  following pages. At the end of this
chapter, a case study using the Pipers Creek watershed
implementation  plan shows how each of these plan
components was developed.

Description of Recommended Best
Management Practices
The first part of the urban runoff pollution prevention and
control plan is a description of the BMPs selected for
implementation.  This   includes  regulatory  BMPs,
municipal  practices, structural BMPs,  and any other
BMP activities selected for implementation.

Regulatory BMPs
Regulatory BMPs, which  play an important role in urban
runoff  pollution prevention and  control, should be
included  and summarized in the control plan. The
summary requires a clear description of the proposed
regulatory changes and the approach to implement the
changes. Regulatory BMPs can address requirements
for an entire community or can be focused on a specific
area  targeted  for  protection. The  level  of  effort
necessary  to implement  the control  program varies
depending  on  these  regulatory  requirements.  This
information  is included in the BMP description  along
with a discussion of the method required to comply with
the regulation,  and any required  enforcement and
maintenance  activities.   Some  regulations  require
passage  through the vote  of a specific board  or
committee,  while others require a  full vote of residents
in the community. The  process needs to be outlined in
the urban runoff pollution  prevention and control  plan.
Finally, costs need to be developed.  These include
one-time costs  associated  with implementing  the
regulation as well as  recurring costs  associated with
education,  information, oversight, and enforcement.
Case studies  of regulatory  control  approaches are
presented at the end  of Chapter  4 (Lewiston, Maine)
and Chapter 7 (Austin, Texas).

Municipal BMPs
Municipal BMPs include the nonstructural  and source
control practices carried out by each responsible  public
entity—street-sweeping,  catch  basin  cleaning, and
cross-connection identification and removal.  For each
of these BMPs, a plan needs to be prepared that details
the frequency of conducting each practice, the locations
at which the practice takes place (preferably on a map),
a schedule of activities, the required staffing, and the
cost. Initial  program startup costs could include training
staff and purchasing equipment. In addition, municipal
BMPs typically include  ongoing  operational costs—
labor for public works  and maintenance staff efforts. A
record system  should also  be  designed  to   track
activities and pertinent data (e.g., pounds  of debris
removed and areas swept).  Municipal source control
and nonstructural practices are discussed  in Chapters
4 and 7 and in the  Lewiston,  Maine, case study,  which
is presented at the end of Chapter 4.
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 Structural BMPs

 Structural BMPs eventually require engineering design
 and construction. At this stage of planning, information
 needed to support each BMP includes  a description,
 pictures, diagrams or concept sketches  (see Figures
 9-1 and 9-2), design information and assumptions, as
   well  as  pertinent  conceptual details of the structural
   BMPs. The details should indicate known site conditions
   such  as existing  structures;  topography; and  other
   site-specific  information such as soil conditions,  utility
   locations,  and  wetlands,  as  available.  Also included
   should be a general  plan of the  watershed showing
                                                                       Influent sluice gate
 Inclined
 find screens
 over effluent
 cninool—\
                   54-in conduit to outfall
                     V
                                    Collection trough -
                                                                                             42-in Influent conduit
 Dewatering system

    Sluice gate and
    target baffle
                                              NaOCI storage
                                              and feed system
                 Effluent
                 channel
                        Overflow
                        weir
   Slope 1/4 in/ft
                                                 Detention tanks
                                            Operations building
                      - Influent channel
 Figure 9-1.  Example CSO control conceptual design of a sedimentation/disinfection facility (Metcalf & Eddy, Inc., 1988).
          Winter
          flow weir
                                                                         Parking lot
                                                                         surface
                     Riprap lined inlet
                     channel/level spreader
                     12 in deep, 4 ft wide-.
                                                                                            Approximate
                                                                                            existing ground
                                                                                              Additional storage
                                                                                              volume, 0.5 in
                       Dewatering
                       outlet pipe
                          Dewatering manhole

                       4-In perforated PVC underdrain
                       S = 0.2%
                    Washed stone, 3/4 to 1 1/2 in

                 Min. depth of sand layer, 12 in
Impermeable geomembrane liner
Figure 9-2.  Example runoff control conceptual design for a filter system (U.S. EPA, 1992).
                                                         158

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locations of the recommended BMPs and the pollution
sources they are designed to address. Final detailed
design plans and specifications for each structural BMP
are developed later, once the plan is approved.

For each BMP, a cost estimate is also developed. After
the  initial  cost  estimate  during  the  alternatives
development step,  this estimate is refined to a more
detailed estimate for purposes of the  implementation
plan.  Improved accuracy is  important since it could
provide  a basis for allocation  of funds.  Given the
uncertainty at this stage (site survey and engineering
work normally is still to be done), contingencies should
be  included in the estimate; and the cost perhaps
should be presented as a range.  For structural BMPs,
ranges  of costs can  be obtained by consulting the
Chapter 7 references. These costs, however, provide
only guidelines and often vary widely depending on
site-specific characteristics, such as  soil  conditions,
depth to bedrock, and level of surrounding development.
Costs include those for design, capital, and operations
and maintenance. Costs for engineering, field surveys,
borings,  construction   labor  and  materials,  and
contingency are also usually included. These costs can
be  presented in terms of present worth and tied to an
applicable price index, such as the Engineering News
Record (EN R) cost index, so the costs can be adjusted
by others in the future.
Proper  operation  and  maintenance   is  particularly
important  to the long-term  functioning of structural
BMPs. A method must be developed for ensuring that
maintenance  requirements   are  included  in  the
management  plan  along  with   inspection  and/or
enforcement mechanisms. For example, if a community
requires an  industry  or  developer  to  construct  a
detention  facility  to  remove  suspended solids from
runoff, the community must also develop a method for
ensuring that the practice is properly maintained. Some
municipalities have addressed this issue by establishing
special  funds designed to  ensure  maintenance  of
BMPs.  In these circumstances,  a municipality might
require  the industry or developer to contribute a fee to
a fund that pays for inspection and maintenance of the
BMP by municipal employees. Another option is for the
municipality to require the private party to perform the
maintenance.  This  option,  however,   gives   the
municipality less control over the BMP and still requires
that the municipality conduct periodic inspections of the
BMPs.

Other Related Activities
Several related activities, which might not fall strictly into
the earlier categories identified, include public participation
and  education,  monitoring,  and maintenance and
enforcement.  Both public participation and education,
and  monitoring  are addressed  as   separate  plan
components later in this  chapter. Maintenance  and
enforcement  is  discussed  under  the  section  on
responsibilities for BMP  implementation. In general,
however, all  BMPs  and activities which  are  to be
included  in  the  program  should be  described  and
discussed as part of the implementation plan.

Schedule of Activities
Because of the complex nature of urban runoff planning,
implementing all the recommended BMPs in a short
time generally is not possible.  In some  cases,  the
implementation schedule  must  allow  time  for  pilot
testing of BMPs in selected  areas,  monitoring  the
results of these pilot tests, and final desigo of full-scale
BMPs.  In   fact,  implementation  of  complex  and
expensive urban runoff BMPs is often conducted in a
series of steps. These steps can include the following
(U.S EPA, 1991):
•  Planning phase: Analyzing, evaluating, and planning
   initial tasks.
•  Preparation phase: Preparing budgets, resources,
   and necessary permits.
•  Pilot-scale implementation phase (only if necessary):
   Testing selected  BMPs for effectiveness  and cost
   prior to full-scale implementation.
•  Full-scale implementation: Designing and constructing
   the selected BMPs.
•  Evaluation/documentation phase:   Evaluating  the
   effectiveness of the implemented BMPs  to guide
   future action; preparing periodic reports documenting
   the results.
These considerations are incorporated into a schedule
with  start  and  finish  dates  for major  tasks  and
milestones.  The schedule should also include  interim
dates of reporting BMP results and monitoring program
results.
Depending on the program's size, the schedule could
be shown by means of a simple bar chart or  a more
complex critical  path  method  (CPM) system using
project scheduling/management  computer  software.
The type of schedule selected depends on the  level of
program complexity—the number of tasks and subtasks
(activities) required, the number of involved entities, the
length of time over which the program will extend, and
the available program management resources.
Implicit in developing an implementation schedule is the
need to set priorities. The program team should review
the recommended  BMPs and determine an order of
implementation  (or phasing),   taking  into  account
extenuating circumstances  in  any particular case.  If
funding  is  a major issue,  for  example,  the  least
expensive recommendations can be implemented early
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 in the process. Individual projects need to be phased in
 accordance with available funding.
 One set of priorities that might be considered is to first
 implement regulatory and nonstructural  controls, then
 evaluate them over time, and later implement structural
 controls. This approach might be effective in developing
 areas where  BMPs can be required as development
 occurs. In addition, nonstructural and regulatory BMPs
 are less costly to implement than structural BMPs. This
 approach  would not be as effective in areas where
 retrofit of BMPs is  necessary.  In general, priorities and
 thus the schedule of program  implementation, must be
 tailored to each situation.

 If the development of public support for the program is
 critical, the team might choose to address BMPs with
 potential for significant pollution reduction. In this case,
 BMPs that could improve the water quality of widely used
 water bodies should be implemented, if possible, before
 other steps are taken. These decisions should  be
 reflected by the implementation schedule. A cost-benefit
 analysis (see Chapter 8) can be used to assist in setting
 priorities. For example, an analysis could be performed
 to determine total cost per pound of pollutant removed
 and projects implemented accordingly.

 Responsibilities for BMP Implementation
 The individuals and entities responsible for implementing
 each aspect of the program must be identified in the
 urban runoff pollution prevention and control plan. Since
 a well-defined institutional framework for urban runoff
 pollution prevention and control might be  lacking, much
 of the effort for implementing plans must come from local
 and regional governments.  Officials at the  state and
 federal levels will likely be responsible for enforcement
 and oversight, and technical and financial assistance
 might also be available.

 To develop a plan,  municipal officials must coordinate,
 initiate activities, and motivate  others in the community
 or other agencies  to get involved. Figure 9-3 is an
 example format showing recommended actions and the
 agencies charged with implementation. Obtaining firm
 commitments from these agencies prior to program
 Implementation is important to the final success of the
 program. Table  9-1 identifies  groups, agencies,  and
 Individuals that can provide  support for aspects of the
 management  plan,  including  monitoring,  design,
 permitting,  regulations, public education, maintenance,
 and enforcement.

 Description of Monitoring Plan

A monitoring program should be conducted during and
after  urban runoff  pollution prevention  and  control
program implementation  to  assist the municipality  in
determining the effectiveness of its overall program in
 achieving water  resource  goals.  Monitoring  during
 program  implementation includes  data collection  to
 measure the overall program effects on water resources
 and  determine the  effectiveness of BMPs. Existing
 water  resource  conditions determined  during the
 planning  process provide  a  good  understanding  of
 water resource quality before program implementation.
 A monitoring plan to assess water resource conditions
 during and after  program implementation allows the
 level  of  resulting improvements to be assessed by
 comparison to existing conditions.

 Trend analyses  are  important  in  understanding the
 effects of watershed activities on water resources, and
 can provide important feedback to assessments of the
 success of urban runoff pollution prevention and control
 measures. Long-term data can be used to demonstrate
 the influence of program activities on water  resource
 quality. Sampling data can also be used to educate the
 public on the effects of urban runoff pollution  on water
 resources and the need for  control. To increase public
 awareness,  information  that identifies the effects of
 urban  runoff  pollution   can   be   disseminated   in
 newsletters, at public meetings, or by other means.

 Overall   program  effectiveness  can   usually   be
 determined  more easily than  the effectiveness of
 individual BMPs. As  part of the urban  runoff control
 program,  a  long-term  monitoring  plan  should  be
 designed   to  measure  program effectiveness  and
 provide program accountability.  The plan  should use
 existing   monitoring   stations  (both  those   used in
 previous studies and those used for collecting additional
 data as outlined in Chapter 5) to collect long-term data
 with which comparisons can be made. In this way, the
 progress  of  the  program  in  addressing   pollution
 problems   and  preventing  further  water   resource
 degradation  can  be determined.  Monitoring  plan
 components  (e.g., a map  of monitoring  stations,  a
 record of  the frequency of sampling at each station, a
 parameter list, and a QA/QC project work plan) should
 be  identified  in a work plan  similar to that  outlined for
 sampling in Chapter 5.

 Collecting sufficient data to  clearly demonstrate BMP
 effectiveness is difficult for many reasons, including the
 variability  of runoff flow and quality, and the difficulty in
 separating the effect of a particular BMP on a receiving
 water. Caution should  be exercised in developing these
 types of monitoring programs because they can be very
 expensive; sufficient data to  reach a  conclusion  might
 not be obtained. More detailed  discussions  of BMP
 effectiveness sampling is available  elsewhere  (U.S.
 EPA, 1976).

The effectiveness of nonstructural and regulatory BMPs
is   difficult to  assess.  These   BMPs  are  usually
implemented slowly over time  and affect a geographically
wide area  (typically within a political boundary). Patience
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  Table &-1. Potential Implementation Responsibilities

  Program Component                   Potentially Responsible Parties
                                          Other Potentially Involved Parties
  Monitoring



  Engineering design



  Permitting and regulatory controls
 Public education
 Maintenance
 Enforcement
 Local boards of health
 State water pollution Control agency
 State marine fisheries department


 Local engineering department
 State department of public works
 SOS

 Local boards of health
 Local conservation office
 Local planning board
 EPA
 State water resources agency
 Federal coastal zone management
 U.S. Army Corps of Engineers

 Regional environmental agency
 Local environmental groups
 Watershed associations
 State environmental agency
 Soil and water conservation districts
 EPA

 Local department of public works
 SCS
 Private owners of BMPs

 Local conservation agency
Local board of health
Planning board
Local code enforcement officer
Federal coastal zone management
U.S. Army Corps of Engineers
EPA
Local environmental groups
University students
Volunteer organizations
Environmental consulting companies

University engineering departments
Engineering consulting companies


Local environmental groups
Environmental consulting companies
                                                                               Local environmental groups
                                                                               Local civic groups
                                                                               Private organizations
                                                                               Cable TV/newspapers
                                                                               Contract maintenance providers
 rating  system  can  be  useful to  assess  program
 effectiveness semiquantitatively over time, or at critical
 periods before and after BMP implementation.

 These types of nonconventional monitoring methods
 are not as direct as demonstrable water resource quality
 improvements, but they are valuable in documenting
 program success.

 Summary of Regulatory Requirements

 Regulatory issues that need to be addressed  include
 both  the implementation of regulatory BMPs  and the
 application for regulatory approvals and permits needed
 to  implement  nonstructural  and  structural  BMPs.
 Regulatory BMPs are  discussed in Chapter  7. The
 urban runoff pollution prevention and control program
 could involve the modification  or  strengthening  of
 existing  regulations, including zoning, site plan  review,
 subdivision, or wetlands protection or the development
 of new regulations.

 In  addition,  a  municipality  must obtain appropriate
 regulatory approvals and permits before implementation
and construction  of BMPs that could alter wetlands,
waterways, or water quality, even if the BMP results in
environmental benefit.  These requirements should be
summarized  as  part  of  the urban  runoff  pollution
                    prevention  and  control  program.  Coordination  with
                    appropriate  agencies  is  advisable  before  applying
                    necessary approvals and permits. Agencies from which
                    permits will be required should be contacted early in the
                    planning  process  to  determine  requirements  for
                    securing all necessary approvals and  permits.

                    Major  permits required in  implementing  urban runoff
                    control BMPs originate at  all levels of government-
                    federal, state, and local. The permits of concern usually
                    address the following issues:

                    • Alterations to wetlands.

                    • Dredging and filling operations.

                    • Disturbances  within  a  specified   distance  of  a
                      waterway.

                    • Soil  and erosion control at construction sites.

                    • Alterations to the water quality of a  water body.

                    • Alterations  to   existing  or  construction   of  new
                      discharges to a  water body.

                    • Impacts on endangered species.

                    • Impacts on historic/archaeological sites.

                    • Impacts on natural resources and ecologically sensitive
                      areas.
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Major permitting programs at the federal level include:
the National Environmental Policy Act (NEPA); the U.S.
Army Corps of Engineers—Section 10 of the Rivers and
Harbors Act  and CWA Section 404;  EPA's NPDES
Permit Program; and the CZMA Federal Consistency
Concurrence  Certificate. Additional requirements  can
be in place for many of the regulatory programs outlined
in Chapter 2. Information is available through regional
EPA offices and the state agencies dealing with these
issues. Requirements for state and local permits are site
specific vary widely,  and  are  available  from  the
responsible local or state agency.

Public Involvement
Support and  involvement of the general  public,  both
homeowners and businesses, is considered crucial to
plan implementation and its ultimate  success. While
public involvement should be an  integral part of the
planning process, a public involvement program should
be developed as part of overall program implementation.

Components of  public  involvement programs can be
wide ranging, involving one or  more of the following
components:
• Program  meetings  and  presentations  to  provide
   information and updates.
• Program materials such as newsletters, fact sheets,
   brochures, and posters.
• School  education programs such as special classes
   and tours.
• Homeowner education programs on individual control
   of urban runoff related pollution.
• Consumer  education  programs   on   appropriate
   product purchasing and handling.
• Business education programs.
 • Media  campaigns  including  radio, newspaper,  or
   television.
 • Coordinating   and  coalition  building  with   local
   watershed or activist groups to support the program.
 The numerous other possibilities include setting  up a
 program  hotline,  sponsoring  special  events,  and
 conducting  surveys. A task force can  be set up to
 coordinate and help focus these activities.
 Public involvement can be approached  in numerous
 ways. The case  study on the Pipers Creek watershed
 at the end of this chapter identifies the elements used
 for that program. The Santa Clara Valley case study at
 the end of Chapter 8 shows how public involvement
 activities  can be identified  and evaluated as  BMP
 options.
Funding Sources and Mechanisms
Since a large percentage of funding for  urban runoff
pollution prevention and control programs comes from
local sources,  this section  focuses on local funding
mechanisms. Sources of funding  at the federal and
state levels are uncertain and likely only to provide a
small percentage of  the total  needed funding. It  is
important to keep in touch with the regional EPA offices
and  the state  agencies dealing  with urban  runoff
pollution prevention and control to determine the current
status of funding for program implementation. Funding
sources usually available to local jurisdictions fall into
the following categories:
• Local funding mechanisms

• Matching fund programs
• Grant programs
An  urban  runoff  pollution prevention  and control
program budget typically  includes   funds  from  a
combination of sources. The actual funding sources
utilized depend on many factors, including the following
(PSWQA, 1989):
• The sustainability of the funds.
• The ease with which the  funds can be obtained.
• The  administrative requirements  of  the  funding
  option.
• The correlation between  the funding option and the
  problem.
•  The typical use made of  the funding.
The construction of a  structural  BMP,  for  example,
typically requires one-time,  short-term funding that can
be obtained through a grant or cost share program. The
development of  a monitoring or maintenance program,
however, typically requires continuing funding.

 Local Funding  Mechanisms
 Regional, state, and federal  storm  water and  NPS
 funding programs are usually intended for small-scale
 projects to  collect  data  and  demonstrate  control
 methods. Larger scale programs, therefore, have to be
 financed primarily through local mechanisms, including
 (U.S. EPA, 1990):

 • General funds
 • Long-term borrowing

 • Pro-rata share fees
 • Storm water utilities
 • Special assessment districts
 General Funds.  General funds  are raised  locally,
 usually through  property taxes, fees, and fines and can
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  be directed to urban runoff pollution prevention and
  control.  The  use  of  general funds  might require
  reallocating existing revenues  or creating additional
  revenue sources. These funds can be used either for
  one-time costs or annual operation and maintenance
  costs.

  Long-Term Borrowing. Local entities can also fund
  pollution prevention and control projects through bonds
  and other long-term borrowing. Funding through bond
  issues is usually used only  for  one-time  expenses,
  such as the design and construction of large structural
  BMPs.

  Pro-Rata Share  Fees. Pro-rata  share fees  can be
  used to finance the construction and maintenance  of
  urban runoff projects. This mechanism requires land
 developers to contribute funds to  a local entity  in
 charge of local BMPs.  Fees are typically  based on a
 technical assessment of the development"s potential  to
 contribute to the  urban  runoff pollution problem. For
 example, a municipality can require developers to pay
 a fee based on the amount of impervious surface  in the
 development. The fees could vary depending on the
 development's location (e.g., watershed or proximity to
 protected resources). These pro-rata share fees are
 often used in currently undeveloped areas where future
 development could threaten water resources.

 Storm Water  Utilities. Many municipalities in urban
 areas have begun to set up storm water utilities. Storm
 water utilities usually assess all existing residential and
 commercial buildings a fee based  on their percentage
 of impervious area. A survey of 25  storm water utilities
 conducted  by  the   Maryland  Department  of  the
 Environment in 1987 outlined  many of the similarities
 and differences among these utility programs (Lindsey,
 1988). According  to the survey, storm water  utilities
 had been established in small  communities as  well as
 large urban centers.  Most utilities are administered by
 local departments of public works, which also have the
 responsibility for operation and maintenance  of BMPs.
 These programs  have  proved  to be good,  stable
 funding sources.

 Special  Assessment Districts.  Some states have
 enacted legislation that allows for the development of
 special  assessment  districts for flood control,  lake
 management, aquifer protection, drainage,  or shellfish
 protection. Once a special district is formed,  funds for
 projects in a district can be raised  by levying fees on
 landowners  in the  district. Such programs are viewed
 as more  equitable forms of financing. Because these
 programs  require approval of residents in the special
district these funding programs can be  difficult to
establish (PSWQA, 1989).
  Matching Fund Programs

  Matching  fund  programs  (also  called  cost share
  programs) can exist at the regional, state, and federal
  level  and are typically restricted to financing specific
  activities or  control  measures.  In these programs,
  entities implementing  control programs  can obtain
  funding for a certain percentage of the cost. Matching
  fund programs have been available from the federal
  government through the Construction Grants Program,
  State  Revolving  Loan  Fund, NPS program (CWA
  Section 319), the Clean Lakes Program (CWA Section
  314),   and  the National  Estuary Program  (CWA
  Section 320). Each of these programs is described in
  Chapter 2. Matching funds are also available from the
  Department of Agriculture through the Soil Conservation
  Service  and  the  Agricultural   Stabilization   and
 Conservation Service.

 Grant Programs

 Regional, state, and federal agencies might also offer
 special  grants  which  typically are limited and  can
 change from  year  to year. Because of the uncertain
 nature of these grants, they are not reliable sources of
 funding for long-term  programs; however, they  can
 provide funding for  short-term  needs. Grants  are
 available through many of the same federal sources as
 for matching funds.

 Summary

 The  final  recommended   urban   runoff  pollution
 prevention and control plan should be summarized in a
 document which can be used by responsible officials
 and agencies  in plan  implementation. An example
 of such a plan is provided in the case study on the
 Pipers  Creek watershed at the  end of this chapter.
 By  developing  a  thorough  and   accessible  final
 implementation document and periodic reports, the plan
 will  have a greater chance of success. In addition,
 valuable  information   can  be  compiled   for  other
 communities.

 While   completion  of  the  urban  runoff  pollution
 prevention  and control  plan signifies the end of  the
 planning process described  in this handbook, it is
 only the  first  step in  the  overall program. Plan
 implementation will likely be a long-term effort and the
 planning is  by  no means  over at this  stage.  As
 implementation and  further monitoring occurs, the plan
 might need to be updated, refined, and modified. When
this  occurs, the planning process  described  in this
handbook (Figure 3-1) may be re-entered at any point.
For example,  a new problem assessment  might  be
needed, a change  in priorities (or  problem ranking)
could be necessary, or new BMP options (or deletion of
BMPs previously thought appropriate) might need to be
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considered. The program needs to be reevaluated and
updated constantly throughout implementation.

As a final note, achieving the critical balance between
resources  expended on  program planning and those
used for program implementation is a challenging task.
The program team must develop a pollution prevention
and   control  plan  using  its  valuable   resources
cost-effectively. Every dollar and manhour not used in
the planning process can be applied to  program
implementation.  Difficult  choices  must  be  made
throughout  the  planning  process  to  ensure  that
technically  defensible  decisions  are  made  while
still  maintaining  adequate   resources   for  future
implementation.
                                           Case Study:
                            Pipers Creek Watershed Action Plan
                       for the Control of Nonpoint Source Pollution


     The Pipers Creek watershed, an urban drainage basin of approximately 3.5 square miles, is located in
     northern Seattle, Washington, bordering Puget Sound. To improve the water quality in Puget Sound and
     its tributaries, a comprehensive study of the Pipers Creek watershed was conducted during 1989 and
     1990 by the city of Seattle and the Washington State Department of Ecology (WA DOE, 1990). This
     study led to the development of the Pipers Creek Watershed Action Plan  for the Control of Nonpoint
     Source Pollution. The plan  presents recommended actions, an implementation schedule,  regulatory
     issues, and remaining needs for the watershed.
     The Pipers Creek Action Plan was developed through a 12-step process that closely follows the 7-step
     process used in this handbook (see Chapter 3). The steps include:

     • Initiate public participation

     • Define existing conditions

    , • Review regulatory requirements

     • Define goals and objectives

     • Define and describe the problem
     • Identify candidate measures to control NPS pollution
     • Employ a practical approach to evaluate candidate pollution control measures

     • Develop criteria for evaluating candidate controls
     • Examine, evaluate, and screen candidates
     • Select most promising source control measures

     • Continue  assessment of selected source control measures

     •  Recommend source control measures and an implementation program
      In this program, the existing conditions were defined prior to developing and stating program goals. Goals
     were reevaluated and redefined at numerous points during the program.
      NPS pollution and erosion problems were of highest concern in the Pipers Creek watershed. A watershed
      management committee (WMC) was created to develop the action plan, made up of local residents and
      representatives of community and environmental organizations,  businesses, and local government
      agencies. The committee determined that, since NPS pollution is difficult to link precisely to sources, a
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  broad range of control measures should be recommended.  The following five programs for controllina
  NFS pollution were developed:

  •  Public education: Since some pollution problems were caused by public actions, public education
    programs were recommended to inform the general public of actions that result in pollution of surface
    waters.

  •  Regulation: Since  some existing regulations could be used to address NFS  pollution, regulatory
    programs were recommended to increase coordination and enforcement of the existing laws and
    regulations designed to prevent water pollution.

  •  Operation and maintenance: Since existing drainage structure operation and maintenance activities
    could be used to reduce NFS pollution, the action plan recommended ways to protect water resources
    through improving and coordinating these  efforts.

  •  Public works: Even with  full implementation of municipal and regulatory control practices throughout
   the  watershed,  pollution  problems  would  still  exist.  The action  plan therefore, included
    recommendations  for structural  control  practices where  appropriate,  to  reduce  water  quality
   degradation.

 •  Monitoring: The action   plan  includes recommendations  for monitoring  management  practice
   implementation to determine the effectiveness of individual practices as well as a recommendation
   for monitoring overall water resources to further characterize the NFS problems.

 The recommendations given within these programs are broad in scope and focus primarily on municipal
 and regulatory controls (Table 9-2). Controls  for specifically identified pollution sources are included in
 the public works recommendations and consist of demonstration projects designed to determine the
 effectiveness of specific structural controls.

 For each of the five programs, WMC has developed detailed recommendations and summarized them
 in an action plan that includes conceptual information on recommended BMPs, a schedule of activities,
 responsibilities involved in implementation, a description of the monitoring plan, a summary of regulatory
 requirements, and  identification of funding  requirements  and sources. The plan also includes a
 discussion of  pollution prevention and reduction activities that have been  implemented already and
 additional water resource data that should be obtained.

 To increase the effectiveness of the public education program, the WMC and the WA DOE recommended
 that some public education  activities begin before the action plan is completed. As a result, a number
 of actions to inform and educate the watershed community have been initiated with the approval of the
 city, including:

 • Posting informational signs at key areas in the watershed.

 • Stenciling storm drains with a warning against dumping wastes.

 • Providing staff assistance to community efforts related to water quality protection.

 • Staging a media event and dedicating a billboard promoting the protection of water quality.

 • Starting a public education pilot project that provides a half-time watershed educational specialist to
  undertake a variety of activities in the watershed.

A detailed plan to implement the recommendations has been  developed, including:

• Obtaining written  commitments from local and state agencies and citizen's groups  responsible for
  implementation; these commitments are important given the wide array of agencies and organizations
  involved in the program.

• Creating an implementation committee staffed  by  community representatives and  members of
  agencies  responsible  for  implementation;  this committee is responsible for evaluating program
  progress.
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Table 9-2.   Pipers Creek Action Plan Recommendations
Public Education
Provide public information during action plan development
Develop a household educational brochure
Hire a watershed specialist to provide education
Develop a park educational display
Develop a watershed educational video
Continue volunteer activities in the watershed
Institute an annual watershed awareness week
Paint signs on storm drains—"Dump No Waste, Drains to
Stream"
Regulatory Controls
Develop a septic system inspection program
Develop a water quality training program for all city
inspectors
Monitor permanent detention systems
Require BMPs at many new construction sites
Install additional pet waste signs
Conduct a study to determine the effectiveness of current
regulations
 Install additional dumping enforcement signs
 Operation and Maintenance
 Develop a program to trace pollution in storm drainage
 systems
 Locate septic systems serving basements
 Expand sanitary sewer system inspections
 Inspect the major sanitary system trunk line in the Pipers
 Creek watershed
Operation and Maintenance (cont)
Develop a program to determine the correct cleaning
schedule for catch basins
Improve maintenance of open drainage ditches
Provide additional trash receptacles in parks
Expand the existing spill-response program
Public Works
Construct a test grassed swale in the watershed
Conduct a program to test erosion controls
Conduct a test program to increase in-system detention
Reduce erosion from an  identified pipe discharge
Reduce erosion from waterside park trails
Install current deflectors to reduce In-stream erosion
Improve the fisheries habitat in park areas
Reduce odor from two sewer systems
Monitoring Program
Create an implementation committee to oversee the action
plan
Conduct routine water quality monitoring
Conduct storm event monitoring in Pipers Creek
Conduct periodic video surveys and a refuse dumping
survey in Pipers Creek
 Periodically review watershed land use
 Require annual agency status reports
 Require annual summary reports of progress in Pipers
 Creek
 •  Developing assessment criteria for the implementation committee to evaluate the program's success;
    assessment criteria should include:
    — source control recommendations implemented,
    - water quality monitoring results,
    — opinion surveys,
    — recycling participation,
    - yard waste collection,
    - results of the annual neighborhood cleanup program,
    - Earth Day participation,
    - return of salmon to Pipers Creek,
    - participation in educational events, and
    - attention from the local media.
  • Developing and implementing a long-term monitoring program, including:
    - routine water resource monitoring,
    — specific storm event monitoring,
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        - visual monitoring, and
        - land use monitoring.

      • Requiring  biannual status reports from each agency responsible for implementation: these reports
        should address:
        - progress and accomplishments in general,
        - problems with implementation,
        - actual versus estimated costs,
        - suggested modifications to the program, and
        — actions for the following year.

      Since the recommendations made in this program rely heavily on the data available to the program team,
      the  initial focus of implementation is on pollution prevention activities, public education, demonstration
      projects, and additional data gathering. In this way implementation is not delayed while further water
      resource sampling is conducted. Additional sampling and assessment of control measures could lead to
      further implementation.
 References

 When an NTIS number is cited in a reference, that
 document is available from:
   National Technical Information Service
   5285 Port Royal Road
   Springfield, VA 22161
   703-487-4650

 COM. 1993.  Camp  Dresser &  McKee.  State of
   California storm water best management practice
   handbooks.  California State Water Quality Control
   Board.

 Dressing, S.A., J.C. Clausen, and J. Spooner. 1992. A
   tracking index for nonpoint source implementation
   projects. Proc. National Rural Clean Water Program
   Symposium. Orlando, FL.

 Lindsey,  G.  1988. A survey of  stormwater utilities.
  Stormwater  Management Adminstration, Maryland
   Department of the Environment.

Metcalf & Eddy, Inc. 1988. Lower  Connecticut River
  phase   II   combined  sewer   overflow  study.
  Massachusetts Division of Water Pollution Control.

PSWQA, 1989. Puget Sound Water Quality Authority.
  Managing  nonpoint  pollution:    an  action   plan
  handbook for Puget Sound watersheds.
 U.S. EPA. 1976. U.S. Environmental Protection Agency.
   Methodology for the study of urban storm generated
   pollution and control. ERA/600/2-76/145.

 U.S. EPA. 1990. U.S. Environmental Protection Agency.
   Financing mechanisms for BMPs. Urban Nonpoint
   Source/Stormwater Management Fact Sheets. U.S.
   EPA Region V. Chicago, IL.

 U.S. EPA. 1991. U.S. Environmental Protection Agency.
   Evaluating nonpoint source control  projects  in an
   urban watershed. In Seminar Publication: Nonpoint
   Source  Watershed Workshop.  EPA/625/4-91/027
   (NTIS PB92-137504).

 U.S. EPA. 1992. U.S. Environmental Protection Agency.
   Casco  Bay  storm  water  management  project:
   Concord  Gully,  Frost Gully  and  Kelsey  Brook
   watersheds. U.S. EPA Region I. Boston, MA.

WA  DOE.  1990.  Washington State  Department of
   Ecology. Pipers Creek watershed action plan for the
   control of nonpoint source pollution: final control plan.
   Pipers Creek Watershed Management Committee.

Woodward-Clyde  Consultants.  1989.  Santa  Clara
  Valley nonpoint source study. Santa Clara  Valley
  Water District.
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                                          Appendix A
                                    Additional References
When an NTIS  number is cited in a reference, that
document is available from:
  National Technical Information Service
  5285 Port Royal Road
  Springfield, VA 22161
  703-487-4650

Hydrology References
Andersen, D.G. 1970. Effects of urban development on
  floods in northern Virginia. U.S. Geological  Survey
  Water Supply Paper 2001-C. Washington, DC.

Hammar, T.R. 1972. Stream channel enlargement due
  to urbanization. Water Resource Research 8(6).

Klein,  R.D.  1979.  Urbanization and  stream  quality
  impairment. Water Resources Bull. 15(4).

Leopold, L.B. 1968. Hydrology for urban planning—a
  guidebook on the hydrologic effect of urban land use.
  U.S. Geological Survey Circular 554. Washington, DC.

Water Resource Sampling References

 Plumb, R.H., Jr. 1981. Procedures for  handling and
  chemical analysis of sediment and water samples.
  Technical  report  no. EPA/CE-81-1. U.S. EPA/U.S.
  ACOE Technical Committee on Criteria for Dredged
  and  Fill  Material. Vicksburg,  MS:  U.S.  Army
  Waterways Exp. Station.
 U.S. EPA. 1973. U.S. Environmental Protection  Agency.
   Biological field and laboratory methods for measuring
   the   quality  of  surface  waters  and  effluents.
   EPA/670/4-73/001. U.S. EPA Office of  Research and
   Development. Cincinnati, OH.
 U.S. EPA. 1975. U.S. Environmental Protection Agency.
   An assessment of automatic sewer flow samplers.
   EPA/600/2-75/065 (NTIS PB-250987).

 U.S. EPA. 1975. U.S. Environmental Protection Agency.
   Sewer flow measurement: a state-of-the-art assessment
   EPA/600/2-75/027 (NTIS PB-250371). Municipal
   Environmental Research Laboratory. Cincinnati, OH.

 U.S. EPA. 1976. U.S. Environmental Protection Agency.
   Design and testing of  a prototype automatic sewer
   sampling  system.   EPA/600/2-76/006  (NTIS
   PB-252613).
U.S. EPA. 1976. U.S. Environmental Protection Agency.
  Methodology for the study of urban storm generated
  pollution  and  control.  EPA/600/2-76/145  (NTIS
  PB-258743). Office  of Research and Development.
  Cincinnati, OH.
U.S. EPA. 1982. U.S. Environmental Protection Agency.
  Handbook for sampling and sample preservation of
  water and wastewater. EPA/600/4-82/029.

U.S. EPA. 1983. U.S. Environmental Protection Agency.
  Guidelines for the monitoring of urban runoff quality.
  EPA/600/2-83/124 (NTIS PB84-122902).

U.S. EPA. 1986. U.S. Environmental Protection Agency.
  Quality criteria for  water,  1986. EPA/440/5-86/001.
  Washington,  DC:  U.S.  EPA Office of  Water,
  Regulations and Standards.
U.S. EPA. 1990. U.S. Environmental Protection Agency.
  Monitoring lake and reservoir restoration.  EPA/440/
  4-90/007.   Prep,   by    North   American   Lake
  Management Society. Washington, DC.
U.S. EPA. 1992. U.S. Environmental Protection Agency.
  NPDES storm water sampling guidance document.
  EPA/833/B-92/001.  Office  of Water.

WA DOE. 1989. Washington State Department of the
  Environment. Guidance for conducting water quality
  assessments. Olympia, WA.

 Other Nonpoint Source Pollution
 References
 Metcalf &  Eddy, Inc. 1991.  Wastewater engineering:
  treatment, disposal, and reuse, 3rd ed. New York, NY:
   McGraw-Hill.
 U.S. EPA. 1992. U.S.  Environmental Protection Agency.
   Economic analysis  of   coastal  nonpoint source
   controls: marinas. U.S. EPA Nonpoint Source Control
   Branch:  Washington, DC.
 U.S. EPA. 1992. U.S. Environmental Protection Agency.
   Storm water  management for industrial activities:
   developing pollution prevention plans and best manage-
   ment practices. EPA/832/R-92/006. Office of Water.

 Woodward-Clyde Consultants. 1991. Urban BMP cost
   and effectiveness. Summary data for 6217(g) guidance:
   onsite sanitary disposal systems. December.
                                                 169

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                                     Appendix B
                           Table of Annotated References
Document Title
Author, Date*
                                                        BMPs Included
                               Information Available
Controlling Urban Runoff: A Practical Manual for Planning Schueler, 1987
and Designing Urban BMPs
Protecting Water Quality in Urban Areas MPCA, 1989
Guide to Nonpoint Source Control U.S. EPA, 1987
Water Resource Protection Technology: A Handfoook of ULI, 1981
Measures to Protect Water Resources in Land
Development
Urban Targeting and BMP Selection: An Information and Woodward-Clyde
Guidance Manual for State NPS Program Staff Engineers Consultants, 1990
and Managers
Combined Sewer Overflow Pollution Abatement WPCF, 1989
Urban Storm Water Management and Technology: An U.S. EPA, 1974c
Assessment
Decision Maker's Storm Water Handbook: A Primer U.S. EPA, 1992c
Urban Storm Water Management and Technology: U.S. EPA, 1977
Update and User Guide
Control and Treatment of Combined Sewer Overflows Moffa, 1990
Detention
Infiltration
Vegetative
Filtration
Quality inlets
Housekeeping
Detention
Infiltration
Vegetative
Quality inlets
Housekeeping
Detention
Infiltration
Housekeeping
Detention
Infiltration
Vegetative
Quality inlets
Housekeeping
Detention
Infiltration
Vegetative
Housekeeping
Collection system
Storage
Treatment
Housekeeping
Collection system
Storage
Treatment
Housekeeping
Detention
Infiltration
Vegetative
Filtration
Quality inlets
Source control
Collection system
Storage
Treatment
Source control
Collection system
Storage
Treatment
General descriptions
Effectiveness
Design
Use limitations
Maintenance
Cost
Examples
General descriptions
Effectiveness
Use limitations
Maintenance
Cost
Examples
General descriptions
Effectiveness
Cost
General descriptions
Effectiveness
Design
Use limitations
Maintenance
Cost
General descriptions
Effectiveness
Design
Use limitations
General Descriptions
Design
Effectiveness
Maintenance
Cost
General descriptions
Design
Maintenance •'
Use limitations
General descriptions
Effectiveness
Design
Use limitations
Maintenance
Examples
General descriptions
Design
Maintenance
Use limitations
General descriptions
Design
Maintenance
Use limitations
                                           171

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Document TlUe Author, Date*
Guidance Specifying Management Measures for Source U.S. EPA. 1993b
of Nonpolnt Pollution in Coastal Waters

I r ' I!



The Fforida Development Manual: A Guide to Sound Livingston et al.
Land and Water Management 1988





Storm Water Management Manual for the Puget Sound WA DOE 1991
Basin





BMPs Included
Housekeeping
Infiltration
Vegetative
Filtration
Quality inlets


Housekeeping
Infiltration
Vegetative
Detention
Filtration
Site planning

Housekeeping
Infiltration
Vegetative
Quality inlets



Information Available
General descriptions
Effectiveness
Design
Use limitations
Maintenance
Cost
Examples
General descriptions
Effectiveness
Design
Use limitations
Maintenance
Cost
Examples
General descriptions
Effectiveness
Design
Use limitations
Maintenance
Cost
Examples
172

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                      Appendix C
            Acronyms and Abbreviations
ARM
ASCS
ATV
BAT
BCT
BMP
BNA
BOD
BOD5
BPJ
CBOD
CCMP
CFR
CMA
CMP
CPM
COD
CSO
CWA
CWO
CZMA
DAF
DEM
DLG
DO
ED
EMC
ENR
EPA
EPT
agricultural runoff model
Agriculture Stabilization and Conservation Service
all-terrain vehicle
best available technology economically achievable
best conventional technology
best management practice
base/neutral and acid extractable compound
biochemical oxygen demand
5-day biochemical oxygen demand
best professional judgment
carbonaceous biochemical oxygen demand
Comprehensive Conservation and Management Plan
Code of Federal Regulations
calcium magnesium acetate
Central Maine Power
critical path method
chemical oxygen demand
combined sewer overflow
Clean Water Act
Comprehensive Watersheds Ordinance
Coastal Zone Management Act
dissolved air floatation
digital elevation model
digital line graph
dissolved oxygen
extended detention
event mean concentration
Engineering  News Record
U.S. Environmental Protection Agency
Ephemeropter, Plecoptera,  Trichoptera
                            173

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  EXAMS
  FEMA
  FHWA
  GC
  GIS
  QMS
  GWA
  HEC
  HSPF
  IBI
  ICI
  I/I
  LC
  LULC
  MCL
  MCLG
  MEDEP
 Mlwb
 MPN
 N/A
 NEP
 NEPA
 NH3
 N03
 NOAA
 NPDES
 NPS
 NURP
 O&M
 OSHA
 PCB
 PCS
 PS
 PSI
 PVC
 PW
QAPP
QA/QC
  Exposure Analysis Modeling Systems II
  Federal Emergency Management Agency
  Federal Highway Administration
  ground-water conservation
  geographic information system
  geographic names information system
  ground water A (classification)
  Hydrologic Engineering Center (U.S. Army Corps of Engineers)
  Hydrological Simulation Program—Fortran
  index of biotic integrity
  invertebrate community index
  infiltration and inflow
  lake conservation
  land use and land cover
  maximum contaminant level
 maximum contaminant level goal
 Maine Department of Environmental Protection
 modified index of well being
 most probable number
 not applicable
 National Estuary Program
 National Environmental Policy Act
 ammonia
 nitrate
 National Oceanic and Atmospheric Administration
 National Pollutant Discharge Elimination System
 nonpoint source
 Nationwide Urban Runoff Program
 operation and maintenance
 Occupational Safety and Health Administration
 polychlorinated biphenyl
 Permit Compliance System
 point source
 pounds per square inch
 polyvinyl chloride
 present worth
quality assurance project plan
quality assurance/quality control
                            174

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QUAL2E
RC
SCS
SDWA
SLAMM
SOD
SS
SSES
STORM
SWMM
SWTR
IDS
TKN
TN
TOC
TSS
 USDA
 USGS
 UV
 VOC
 WADOE
 WASP4
 WMC
 WQ
 WSE
Enhanced Stream Water Quality Model
resource conservation
Soil Conservation Service
Safe Drinking Water Act
Source Loading and Management Model
sediment oxygen demand
suspended solids
sanitary sewer evaluation survey
Storage, Treatment, Overflow, Runoff Model
Storm Water Management Model
Surface Water Treatment Rule
total dissolved solids
total Kjeldahl nitrogen
total nitrogen
total organic carbon
total suspended solids
 U.S. Department of Agriculture
 U.S. Geological Survey
 ultraviolet
 volatile organic compound
 Washington Department of Ecology
 Water Quality Analysis Simulation Program
 watershed  management committee
 water quality
 water surface elevation
                              175
                   «,.S. GOVERNMENT PRINTS: OFFICE: 1995-650-006/22045

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