Submitted to:
EPA Region I
Boston, Massachusetts
Storm Water Quality
Control in the
Merrimack River
Basin
September 30, 1992
& Eddy
J Ftc,
BOSTON, MA O22o3-2 1 1

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Metcalf & Eddg
An Air & Water Technologies Company
September 30, 1992
Mr. Robert Morehouse
United States Environmental Protection Agency, Region I
JFK Federal Building
Bostn, Massachusetts 02203
Subject:
EPA Work Assignment 2-15: Storm Water Quality Control in the Merrimack
River Basin
Dear Mr. Morehouse:
We are pleased to transmit the report entitled “Storm Water Quality Control in the Merrimack
River Basin.” This report contains an overview of storm water and nonpoint source pollution
issues, a review of control practices, a review of controls in four Merrimack River basin
communities, recommended control practice improvements, and a summary assessment
procedure for communities to follow in investigating their current storm water and nonpoint
source controls.
Thank you for the opportunity to work on this project.
Very truly yours,
David R. Bingham
30 Harvard Mill Square Wakeheld. MA 01880
Mailing Address. P0 Box 4043. Woburn MA 01888-4043
617-246-5200 FAX 617-245-6293

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TABLE OF CONTENTS
Page
LIST OF TABLES ii
PURPOSE 1
OVERVIEW OF STORM WATER AND NPS POLLUTION ISSUES 2
Hydrologic Changes 2
Increased Pollutant Discharge 3
REVIEW OF CONTROL PRACTICES 9
Regulatory Controls 12
Source Controls 15
Structural Controls 18
EXISTING CONTROLS IN FOUR MERRIMACK RIVER BASIN COMMUNITIES 23
Regulatory Controls 24
Source Controls 36
Structural Controls 38
STRENGTHS AND WEAKNESSES OF IMPLEMENTATION 38
Flood Control 40
Storm Water Quality 40
General Site Development 41
RECOMMENDED IMPROVEMENTS 41
Regulatory Controls 42
SUMMARY OF ASSESSMENT PROCEDURE 46
Investigate Existing Regulatory and Source Control Measures 46
Investigate Recent Land Development 48
Assess Water Resources 49
Strengthen Controls 50
REFERENCES 51
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LIST OF TABLES
Page
Table 1. Summary of NPS Pollutants, Sources, and Effects 4
Table 2. Pollutants of Concern for Various Water Resources 5
Table 3. Urban Storm Water Runoff Pollution Controls 10
Table 4. Storm Water and NPS Control References 11
Table 5. Existing Regulatory Controls 26
Table 6. Existing Source Controls 37
Table 7. Site Evaluation Checklist 39
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STORM WATER QUALiTY CONTROL IN THE MERRIMACK RIVER BASIN
PURPOSE
Storm water runoff and nonpoint source (NPS) pollution have been found to cause problems in
water resources . throughout the United States. Because of the site specific nature of these
problems and the ability of communities to control such pollution, effective solutions can come
from actions taken at the local level. The purpose of this document is to provide municipal
officials with information on storm water and NPS pollution control and how to improve existing
regulations and practices to better accomplish such control. The document provides:
• Background information on the effects of land development on storm water
hydrology and pollution and their impact on various receiving water resources
• A brief description of various types of control measures used to prevent and
remove pollution from storm water runoff
• A descnption of the current regulations and practices that address storm water
pollution in four Merrimack River basin communities
• Recommendations to strengthen regulatory requirements and source controls for
storm water pollution control
• A summary of the assessment procedure used so that other communities may
investigate and strengthen their storm water control regulations and practices.
In developed areas it is difficult, expensive, and time-consuming to construct pollution controls
once a storm water pollution problem already exists. It is more cost-effective to prevent
potential pollution problems prior to the occurence of development or to implement controls
during redevelopment. This document, therefore, emphasizes the importance of implementing
storm water pollution controls as regulatory requirements rather than having to correct problems
after the fact in existing developments.
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OVERVIEW OF STORM WATER AND NPS POLLUTION ISSUES
Storm water and NPS pollution is derived from diffuse or widespread sources, is usually
associated with rainfall, snow melt runoff, or percolation, and may lack an easily identifiable
point of entry. To fully attain the beneficial uses identified for a community’s water resources,
implementation of effective storm water and NPS pollution controls is often necessary. NPS and
storm water pollution are inherently difficult to address because of the large number and types
of sources, the quantity and impacts of which are difficult to assess. The best solutions stress
management (rather than treatment) techniques, with reIiance on local control measures.
At the federal level, EPA is starting to address storm water runoff pollution through the National
Pollution Discharge Elimination System (NPDES) permit program. Municipal storm water
runoff is now a permitted point source if it is derived from medium or large municipalities
(greater than 100,000 population); however the trend is to regulate storm water runoff from
smaller and smaller communities. Within existing regulatory authority, communities already
have the ability to control impacts from storm water and NPS pollution. This is because land
development and intensive land uses lead directly to many of the problems associated with storm
water and NPS pollution control. These problems can be divided into two basic categories:
hydrologic changes and increased pollutant transport.
Hydrologic Changes
When precipitation contacts the ground surface, it can take several paths. These include
returning to the atmosphere by evaporation or evapotranspiration, 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
water. Land development replaces permeable surfaces with impervious surfaces (roof tops,
roads, sidewalks, parking lots, etc.) designed to remove rainfall as quickly as possible.
Increasing the proportion of paved areas decreases the infiltration and evapotranspiration paths
of precipitation, thus increasing the amount of precipitation leaving the area as runoff. In
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addition, the intensity of runoff is magnified by urban development and increases in impervious
surfaces. When overland flow through natural vegetation is replaced by storm drainage systems,
the time it takes for storm water to travel to a receiving water is reduced.
Changes to hydrology expected for a moderately developed watershed include (Shueler, 1987):
• Increased peak discharges and frequency of high flows
• Increased volume of storm runoff
• Decreased time for runoff to reach the receiving water
• Increased frequency and severity of flooding
• Reduced flow during periods of prolonged dry weather
• Greater runoff and water velocity during storm events
Each of these changes leads to increased pollutant transport and loading to receiving waters.
As peak discharge rates increase, erosion and channel scouring become greater problems. The
eroded sediments also carry nutrients, metals, and other pollutants associated with them. In
addition, increases in runoff volume result in greater discharges of pollutants. These and other
effects result in increasing pollution problems as increased development occurs.
Increased Pollutant Discharge
In addition to the effects of hydrologic changes on storm water pollution loads, land development
leads to an increase in pollutant loadings in runoff. The increased pollutant loadings result from
a combination of higher total and peak runoff volumes caused by the hydrologic changes
discussed above, and an increase in the concentrations and amounts of pollution associated with
developed land. Table 1 (EPA, 1992) lists the primary categories of pollutants that result from
urban runoff, parameters typically monitored for each category, potential pollutant sources, and
associated potential effects.
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TABLE 1. SUMMARY OF NPS POLLUTANTS, SOURCES, AND EFFECTS
; ;: j
CATE( O Y . PARAMEI RS
BL SO R9

Solids Organic and Inorganic .
TSS
Turbidity
Dissolved Solids
Urban/Agricultural Runoff
CSOs
Turbidity
Habitat Alteration
Recreational & Aesthetic Loss
Contaminant Transport
Navigation/Hydrology
Nitrate
Nitrite
Ammnnia
Organic Nitrogen
Phosphate
Total Phosphonis
Urban/Agricultural Runoff
Landfills,Septic Fields
Atmospheric Degradation
Erosion
Surface Waters
Algal Blooms
Ammnnia Toxicity
Groundwater
Nitrate Toxicity
Total Coliforms
Fecal Coliforms
Fecal Streptococci
Viiuses
Urban/Agricultural Runoff
Septic Systems
CSOs
Boat Discharges
Domestic/Wild Animals
Ear/Intestinal Infections
Shellfish Bed Closure
Recreational/Aesthetic Loss
BOD
COD
TOC
Urban/Agricultural Runoff
CSOs
Landfihls,Septic Systems
DO Depletion
‘Odors
Fish Kills
Toxic Trace Metals
Toxic Organics
Pesticides/Herbicides
Underground Storage Tanks
Hazardous Waste Sites
Landfills
Illegal Oil Disposal
Industrial Discharges
Lethal and Sublethal to hnmnnc
and other organisms
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The predominant sources of runoff and NPS pollution include urban storm-generated runoff,
construction, and agricultural activities. Additional sources include atmospheric deposition,
material storage, highway and bridge maintenance, illegal dumping or disposal, auto salvage
yards, vehicle washing and processing areas, snow dumping areas, utility right-of-ways, surface
runoff from ifiling stations, sediments (either through resuspension or through release of
pollutants from undisturbed sediments), sewer system leaks, domestic and wild animals, litter
from natural vegetation, and non-storm water discharges to separate storm drainage systems
(Morehouse, 1988). For municipalities, urban storm-generated runoff in industrial, commercial,
and residential areas as well as construction activities represent the most prevalent sources.
Outlying agricultural activities can also play a role in some areas.
The effects of storm water and nonpoint source pollutants are different for different water
resource types. The pollutants of concern to a given municipality will, therefore, depend on the
types of water resources present in that community and the desired uses of those waters. Table
2 indicates the water resources that are potentially impacted by various runoff and nonpoint
source pollutants.
TABLE 2. POLLUTANTS OF CONCERN FOR VARIOUS WATER RESOURCES
Drinking
Water
Stream
River
Wetland
Lake
Estuary
Suspended Solids and Sediment
•
•
•
I
S
•
Nutrients
S
I
S
S
I
Pathogens
S
I
I
I
Oxygen Demanding Substances
I
I
S
S
Toxics
I
S
I
S
I
I
Sodium and Chloride
S
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Suspended Solids
Suspended solids (sediment) are 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 stream banks.
Although some sedimentation is natural, construction, farming, and urbanization can 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 soil erosion, deposition from wind erosion, litter (both
manmade and naturally produced), and road sanding. These solids also carry nutrients, metals,
and other substances that can impact the water resource and aquatic life.
Sedimentation can have substantial biological, chemical, and physical effects in receiving waters.
Suspended solids can make the water look cloudy or turbid, diminishing the aesthetic and
recreational qualities of the water body while reducing the growth of algae and submerged
aquatic vegetation. Once the solids settle out and become deposited as sediment, they can
smother bottom dwelling species and act as a sink for pollutants which can later resuspended.
Since solids can cause problems in either the suspended or deposited state, they impact all water
resource types.
Nutrients
The nutrients that are of primary concern to water quality and that are present in high
concentrations in storm water are nitrogen and phosphorus. Nutrients are associated with
agricultural and urban runoff, atmospheric deposition, leachate from landfills and septic systems,
and erosion. Nutrient additions can .result in eutrophication, or.over enrichment of receiving
waters, which can cause excessive algal growth. In many cases, nutrients contributed from
urban runoff originate from chemical fertilizers and thus are in a dissolved form readily utilized
by algae in the receiving waters. Phosphorus is generally the most important nutrient in
freshwater because it is growth-limiting, while nitrogen tends to limit growth in marine waters.
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Nutrient enrichment cai result in severe algal blooms, either in the water column or in stream
and lake beds, that can cause unpleasant odors and otherwise detract from aesthetic value. High
densities of certain algal species can result in taste and odor problems in drinking water from
reservoirs. More seriously, some marine algal species contain toxins that can be harmful to
humans eating affected fish or shellfish. Also, eutrophication can result in depletion of dissolved
oxygen in the water column. Generally, nutrients cause problems in slow moving waters that
allow for the development of algal blooms, such as lakes, coastal areas, large rivers, and
wetlands. Therefore, they are generally not considered a problem in fast moving urban streams,
except as 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 indicator bacteria, such as coliform, fecal coliform or
fecal enterococci are used as indicators of pathogens and of potential risk to human health.
Potential health risks are associated with primary and secondary contact recreation, such as
swimming, and with consumption of contaminated fish and shellfish in areas affected by urban
runoff.
Bacterial and viral pathogens are for the most part attributed to livestock in agricultural areas
and runoff in urban areas. Other sources of these organisms can include failed septic systems,
landfills, or combined sewer overflows and unauthorized sanitary sewer cross connections in
storm drains. Like nutrients, pathogens generally cause water quality degradation in slow
moving waterways and resources used by humans for primary and secondary contact recreation
or sheilfishing. Pathogens are, therefore, primarily considered pollutants of concern in drinking
waters, slow moving rivers, lakes, and estuaries; Pathogen contaminated discharges to wetlands
or fast moving urban streams are typically less important due to the lack of recreational and
fishing uses of such waters.
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Oxygen-Demanding Matter
As discussed above, microorganisms consume organic matter that is deposited in water bodies
by storm water runoff. In the process, oxygen is removed from the water. Organic enrichment
is caused by agricultural and urban runoff, combined sewer overflows, and leachate from septic
tanks and landfills. A sudden release of oxygen-demanding substances into a waterbody during
a storm can result in the total depletion of oxygen and in 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). This oxygen demanding matter
is primarily a concern in waterbodies that support aquatic life, such as rivers, lakes, and
estuaries. It is, therefore, generally a less important considerations for fast moving urban
streams and wetlands.
Toxic Pollutants
Toxic pollutants include trace metals and organic chemicals. Heavy metals in urban runoff can
result from the breakdown of products such as trash cans and car bumpers, fallout from
automobile emissions, and other metal products. Potential sources of toxic pollutants include
vehicular residues, industrial areas, landfills, hazardous waste sites, leaking underground and
aboveground fuel storage tanks, and agricultural areas at which chemicals are used. Other
potentially toxic compounds in storm water and NPS pollution include oil and grease from
vehicles and construction equipment. These compounds are generally in runoff from roads,
parking lots, service areas, and construction sites, and can be a constituent of landfill leachate.
Oil and grease products can be adsorbed to sediment particles and be deposited in the bottom
sediments. These compounds can be toxic to aquatic organisms and can bioaccumulate in fish
and shellfish, potentially resulting in toxic effects to humans eating this tainted food. Because
of the potentially acute and chronic effects of toxic pollutants, efforts should be made to
appropriately limit their discharge to all water resource types.
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Sodium and Chloride
Discharges of sodium and chloride to surface waters result primarily from road sailing
operations during winter months and snowmelt during the early spring thaws. These discharges
can affect the taste of drinking water supplies and be harmful to people on low sodium diets.
Of secondary importance is its potential impact on salt intolerant plant species. However, the
concentrations of sodium and chloride in runoff are typically small enough to not cause serious
problems, especially in resources with continuous flushing (rivers and streams). Sodium and
chloride discharges are, therefore, of concern in drinking water supplies and lakes.
REVIEW OF CONTROL PRACTICES
Because of the lack of funding for storm water pollution control activities as well as the
difficulty in implementing controls for multiple source types at many locations with intermittent
(rainfall-driven) discharges, the emphasis of storm water pollution control measures is typically
on nonstructural controls and low-cost structural controls designed to prevent pollution.
Nonstructural controls include regulatory measures that prevent NPS pollution problems by
controlling land development, and source controls that seek to reduce pollutant buildup or lessen
its availability for wash-off during rainfall. Low-cost structural controls remove pollutants from
runoff by using natural processes, such as settling, filtering, biological breakdown, or uptake
by vegetation, or using small facilities with no mechanical or electrical equipment, such as water
quality inlets and oil and grease traps.
Depending on the pollutant control mechanisms they use, storm water runoff and NPS pollution
control practices are divided into the following categories:
• Regulatory (land use) controls
• Source controls
• Structural controls
- Detention facilities
- Infiltration facilities
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- Vegetative practices
- Filtration practices
- Water quality inlets
Table 3 lists the most commonly used urban storm water controls. This section provides a brief
description of some of the more important controls. More detailed references, such as those
shown in Table 4, should be consulted before selecting, designing, and implementing controls.
TABLE 3. URBAN STORM WATER RUNOFF POLLUTION CONTROLS
Regulatory Controls Detention Facilities
Land Use Regulations Extended Detention Dry Ponds
Protection of Natural Resources Wet Ponds
Land Acquisition Constructed Wetlands
Source Controls Infiltration Facilities
Street Sweeping Infiltration Basins
Catch Basin Cleaning Infiltration Trenches/Dry Wells
Fertilizer and Pesticide Management Porous Pavement
Animal Waste Removal
illicit Connection Identification and Removal Vegetative Practices
Solid Waste Management
Reduced Roadway Sanding and Salting Grassed Swales
Filter Strips
Filtration Practices
Filtration Basins
Sand Filters
Water Quality inlets
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TABLE 4. STORM WATER AND NPS CONTROL REFERENCES
Document Title Author Controls Induded Information
Available
Controlling Urban Runoff: A Schueler Detention General Descriptions
Practical Manual for Planning and Infiltration Effectiveness
Designing Urban BMPs, 1987 Vegetative Design
Filtration Use Limitations
Quality Inlets Maintenance
Cost
Examples
Protecting Water Quality in Urban MPCA Source Control General Descriptions
Areas, 1989 Detention Effectiveness
Infiltration Use Limitations
Vegetative Maintenance
Quality Inlets Cost
Examples
Guide to NPS Control, 1987 EPA Source Control General Descriptions
Detention Effectiveness
Infiltration Cost
Water Resource Protection Urban Land Source Control General Descriptions
Technology: A Handbook of Institute Detention Effectiveness
Measures to Protect Water Infiltration Design
Resources in Land Development, Vegetative Use Limitations
1981 Quality Inlets Maintenance
Cost
Urban Storm Water Management EPA Source Control General Descriptions
and Technology: An Assessment, Collection System Design
1974 Storage Maintenance
Treatment Use Limitations
Coastal Nonpoint Source Control EPA Source Control General Descriptions
Program: Management Measures Infiltration Effectiveness
Guidance - Draft, 1992 Vegetative Design
Filtration Use Limitations
Quality Inlets Maintenance
Cost
Examples
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Regulatory Controls
Urbanization increases the amount of impervious land area, which, in turn, leads to increases
in storm water runoff with its associated pollutants. Municipalities can prevent or reduce many
of these pollution problems by implementing regulatory controls designed to reduce the amount
of impervious area and to protect valuable resources. The major categories of regulatory
controls include:
• Implementing land-use regulations
• Restricting development in valuable natural resource areas
• Acquiring parcels of land or buffer zones to prevent development
Following is a discussion of some common municipal regulatory practices that can be used to
control storm water and NPS pollution. Estimates of pollution control that can result from
implementing these controls are contained in a number of documents, such as those listed in
Table 4. One table from a recent publication has been reproduced in Appendix A as an example
of the type of information that is available.
Land Use Regulations
Land-use regulations can be used to encourage development patterns compatible with storm
water runoff and NPS pollution control objectives. Land-use regulations can include zoning
ordinances, subdivision and site plan regulations and review requirements, and environmental
resource regulations such as wetlands protection.
Zoning. Zoning ordinances specify the density and type of development that can occur. in given
areas. Zoning density controls acreage requirements for certain land uses and associated
setback, buffer, and lot coverage requirements. Zoning use directly and indirectly affects what
types of pollutants may be stored or used on the site. Pollutant intensive uses can be restricted
or eliminated in sensitive zones or allowed only under special permit approval. Zoning
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regulations can serve to address both the hydrologic and pollutant discharge concerns involved
in new development. Examples of types of zoning practices designed to protect water bodies
include:
• Cluster Development : 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 types of 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 waterbodies.
• Performance Standards : permitting certain land uses, usually industrial activities,
only if they meet specific performance criteria.
Communities can utilize these zoning practices to ensure that land uses in specified areas of the
municipality are appropriate given their proximity to nearby water resources. Implementing
special zoning restrictions in especially sensitive areas, such as a water supply watershed, can
serve to reduce development in the watershed and ensure that any development taking place is
appropriate.
Subdivision Review. When land is divided into separate parcels for development, communities,
under Massachusetts State Law, require the developer to go through a subdivision review
process. Parcels that have sufficient frontage on an approved public way are classified as
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“Approval Not Required” and do not go through preliminary and definitive plan review. All
other proposed subdivisions must go through this review. During this review, municipalities can
include requirements for drainage, grading, and erosion control and provisions for buffer areas,
open spaces, and maintenance. In this way, municipalities can ensure that proper practices are
designed into the development.
Site Plan Review. Prior to development of certain activities, municipalities may require a site
plan review process to ensure compliance with zoning, environmental, health, and safety
requirements. In this review, developers are usually required to consider how site development
will affect such concerns as traffic circulation, air quality, and ambient noise levels. Developers
may also be required to submit information on the natural drainage characteristics of the site and
plans for erosion control, the retention and protection of wetlands and water resources, and the
disposal of construction-related wastes. However, criteria which can impact storm water and
NPS pollution are not often specified in the site plan review regulations.
Protection of Natural Resources. Municipalities can also protect water resources by restricting
development in lands, such as floodplains, wetlands, stream buffers, steep slopes, and wellhead
areas. By implementing special development restrictions in these areas, the potential for storm
water and NPS pollution can be reduced. These protection practices usually take the form of
special protection districts or overlay zones.
Land Acquisition
In addition to zoning and resource protection, municipalities can purchase land or obtain
conservation easements within a watershed to control land development. In this way, valuable
-. resources can be protected from the effects of development. Municipalities can acquire land to
convert to parks or to maintain as open space; however, this can be a very expensive approach.
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Source Controls
Source controls include nonstructural practices that can reduce the availability of storm water
runoff and NPS pollutants. Some of the more common practices in current use in many
municipalities use include:
• Street sweeping and catch basin cleaning
• Reduced fertilizer, pesticide, and herbicide use
• Animal waste removal
• Illicit connection identification and removal
• Solid waste management
• Reduced roadway sanding and salting
Although effectiveness of these practices can be difficult to predict, the table shown in Appendix
A indicates the general removal effectiveness expected from urban housekeeping (street sweeping
and catch basin cleaning), fertilizer control and household hazardous waste collection.
Street Sweeping and Catch Basin Cleaning
Frequent street sweeping and catch basin cleaning can prevent the accumulation of dirt, debris,
and their associated pollutants, and the subsequent deposition of these pollutants in storm drains
and waterways. In most municipalities, these tasks are conducted at scheduled intervals. It has
been shown that street sweeping results in significant pollutant reductions only if an intensive
schedule (once or twice per day) is adhered to consistently. It is, however, not practical for
communities to maintain this level of Street sweeping. In addition, catch basin cleaning has not
been shown to result in significant pollutant reductions. Cleaning rates of twice per year are
generally recommended. Although neither of these practices results in significant pollutant
eii ival,regulai sfreet sweeping and catch basin cleaning can remove some of the large floatable
litter that is unsightly in urban surface waters.
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Reduced Fertilizer. Pesticide. and Herbicide Use
Fertilizers, pesticides, and herbicides washed off the ground during storms can contribute to
water pollution. Generally, agricultural land uses are primarily responsible for these pollutants.
However, some communities use these chemicals on park lands, and homeowners utilize them
on their lawns. These can be sources of pollutants in urban areas. Controlling the use of these
chemicals on municipal lands and educating the public can, therefore, help reduce nutrient and
toxics concentrations from these fertilizers and pesticides. However, unless existing practices
include significant fertilizer or pesticide use near waterbodies, minimal nutrient load reductions
would occur.
Animal Waste Removal
Domesticated and wild animal wastes represent a source of bacteria and other pollutants that can
be washed into surface waters by storm water runoff. These pollutants can be reduced by
reducing the animal waste on paved surfaces. Municipalities can enact and enforce leash laws
and pet waste cleanup ordinances. The effectiveness of these programs in reducing pollutant
loads is difficult to assess and to implement, since it depends on voluntary actions by private
citizens. It is anticipated that minimal pollutant load reduction would occur form this practice,
except perhaps where large concentrations of pets exist.
Illicit Connection Identification and Removal
Unauthorized and inappropriate connections in drainage systems can cause continuous dry
weather discharges of sewage or toxic materials and can exist for many different reasons. In
the past, connector pipes between sanitary sewers and storm drains. migh.t h ve• 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. As new construction occurs, accidental connections to the wrong system can also
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occur. Because these cross connections are not typically documented, pollution resulting from
them can be difficult to locate. Municipalities can, however, develop a program to locate and
eliminate these connections. These programs are similar to infiltration/inflow studies conducted
by municipalities on sanitary sewer systems. Detailed information on locating and eliminating
these cross connections is available in a draft EPA document entitled “Assessment of Non-Storm
Water Discharges into Separate Storm Drainage Systems” (Pitt, 1990).
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 particularly high waste times. For example, some municipalities
in the northern United States provide extra collection services during the fall to collect leaves.
These waste collection practices, although designed for aesthetic reasons, can help to reduce
pollutant discharge to surface waters. Actual reductions in 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.
Reduced Roadway Sanding and Salting
In areas with freezing road conditions, sand and salt are used to improve driving conditions in
the winter months. These can be washed off the roadways, however, and pollute receiving
waters. The problem is exacerbated during spring snow melt and early spring rainstorms when
most of these pollutants are available for transport. Limiting the use of chemicals for snow and
ice control to the minimum necessary for public safety and utilizing proper equipment can reduce
these problems. Also, deicing alternatives,such as calcium magnesium acetate (CMA), cãn be
used in some cases, although they are expensive.
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Structural Controls
Structural controls can be used to remove pollutants from runoff. In highly developed areas,
regulatory controls are instituted mainly during the redevelopment process and source control
practices may not be sufficient. In these cases, it may be necessary to retrofit structural controls
into existing developments. In addition, structural controls can be implemented in undeveloped
areas through regulatory requirements that specify their use. The approximate pollutant
removals for various structural controls is indicated in the table in Appendix A. Similar tables
and information are contained in the references cited in Table 4.
Structural controls seek to remove pollutants from runoff through natural processes, such as
settling, filtration, and vegetative uptake. Proper functioning of these practices depends on
following strict design criteria and maintenance schedules. It is important that structural controls
be regularly inspected and maintained. Common maintenance practices include replanting and
mowing vegetation, removing accumulated sediment, and unclogging outlet structures. Detailed
information on the design and maintenance of the following structural controls are contained in
the documents listed in Table 4.
Detention Facilities
One of the most common structural methods for controlling storm water runoff 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 period of temporary runoff storage
results primarily from settling of solids and their associated pollutants (nutrients, metals).
Extended Detention Dry. Ponds. Many development projects have involved constructing dry
ponds to control peak runoff. These ponds can also be used for pollution control, where the
ponds are designed with structures to restrict the velocity and volume of runoff discharges. Dry
ponds detain the runoff so that heavier particles settle, removing suspended solids. Vegetation
in the dry ponds also provide pollutant removal through filtering and vegetative uptake.
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Although dry ponds remove suspended solids and their associated pollutants, they are less
effective at removing dissolved pollutants and microorganisms.
Wet Ponds. The design of wet ponds is similar to that of dry ponds except that a permanent
pooi of water is maintained in the ponding area. Once the capacity of a wet pond is exceeded,
collected runoff is discharged through an outlet structure or an emergency spillway. While the
runoff is detained, settling of solids takes place. In addition, many wet ponds are vegetated with
plant species, which can often remove pollutants, such as nutrients, from the runoff before it is
discharged to the receiving water. The continuous ponding of water in wet ponds improves the
pollutant removal process over that found in dry ponds.
Constructed Wetlands. Artificially constructed wetlands may be effective in removing urban
storm water pollutants and in flood attenuation. Proper design of artificial 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 systems. Wetland systems
also reduce runoff velocity, thereby promoting settling of suspended solids. Plant uptake
accounts for nutrient removal as well as removal of a portion of the oil and grease and metals
from runoff. In addition, plant material can serve as an effective filter medium, and
denitrification processes can serve to remove nitrogen.
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 discharges into the ground
water. Pollutant removal occurs primarily through filtration, which is effective at removing
solids, those pollutants that adhere to solids; and bacteria. Infiltration is less effective at
removing dissolved pollutants, such as nutrients and some metals.
Infiltration Basins. Infiltration basins are similar to dry ponds, except that infiltration basins
are designed to permanently capture all or part of the incoming flow. Flow entering an
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infiltration basin travels to the ground water through the soil. Infiltration basins provide storm
water pollutant removal through both filtration and settling, but the primary pollutant removal
mechanism is filtration. Infiltration basins are particularly effective in removing bacteria,
suspended solids, insoluble nutrients, oil and grease, and floating wastes. They are, however,
less effective at removing dissolved nutrients, some toxics, and chlorides.
Infiltration Trenches/Dry Wells. These practices differ from inifitration basins because they
are located below ground and usually must be built “off line” (only a specific volume of runoff
enters an infiltration facility with the balance continuing along another path) because of the
limited storage area they provide. Subsurface infiltration systems can consist of precast concrete
structures with holes in the sides and bottom surrounded by washed stone. These structural
controls use filtration as the primary pollutant removal mechanism, much like onsite wastewater
treatment systems used in many communities. They 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.
Porous Pavement. Paved roads and parking areas are major contributors to storm water runoff
problems in urban areas because they increase watershed imperviousness. Porous pavement,
however, allows water to flow through a porous asphalt layer and into an underground gravel
bed. Using this porous pavement can, therefore, reduce runoff volume and pollutant discharge.
This practice is used in areas with gentle slopes and is generally designed into parking areas that
receive light vehicle traffic. These systems are, however, designed to remove only fine grained
particles because coarse particulate pollutants can clog the pavement. In these systems, pollutant
removal primarily occurs after the runoff has inifitrated into the underlying soils....
Vegetative Practices
Urbanization results in the elimination of vegetation and increases in impervious area.
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Vegetative practices can be implemented in urban areas to decrease the impervious area and
promote runoff infiltration and solids capture. These practices provide moderate to low pollutant
removal and can be used for pretreatment for the removal of suspended solids from runoff prior
to more intensive treatment by other practices.
Grassed Swales. Grassed swales are channels covered with vegetation used to replace 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. Grassed swales remove pollutants through filtering by the vegetation and
settling of solids in low flow areas. However, infiltration of the runoff and associated pollutants
is probably the most important pollutant removal process. Because of these pollutant removal
mechanisms, swales are most effective at removing suspended solids and their associated
pollutants. They provide little removal of dissolved pollutants.
Filter Strips. Filter strips are similar to grassed swales. Runoff enters these systems as
overland flow evenly distributed across the filter strip. Because these systems can accept only
overland sheet flow, they are usually used in conjunction with level spreading devices. Filter
strips are most effective at removing pollutants such as sediment, organic material, and some
trace metals. They are less effective at removing dissolved pollutants.
Filtration Practices
Filtration practices provide runoff treatment through settling and filtering through a specially
placed layer of sand or other filtration medium. Flow enters the structure, ponds for a period
of time, and ifiters through the media to an underdrain that discharges to a surface water. These
practices attempt to simulate the pollutaht removal of infiltration practices using less land area.
Filtration Basins. Storm water runoff diverted to a filtration basin is detained, allowed to
percolate through filter media, and collected in perforated pipes, that transport the filtered runoff
to the receiving water. These systems have been used extensively in Austin, Texas, showing
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good pollutant removal efficiencies and low failure rates. Pollutant removal in filtration basins
occurs because of settling during the initial ponding time and filtering through the soil media.
Sand Filters. Sand ifiters are similar to the filtration basins outlined above but are designed to
reduce the amount of land required by building them below ground. These systems consist of
a basin for settling of suspended solids and a filtration chamber. Runoff enters the basin and
collects to the basin capacity. It then overflows into a sand-filled chamber that provides
filtration and is discharged through an outlet pipe in the bottom. The use of sand filters for
storm water runoff treatment is still experimental and has been implemented in a demonstration
in the state of Maryland. Sand filters use the same pollution removal mechanisms as filtration
basins and will provide similar pollutant removal. Initial removal of suspended solids occurs
through settling in the basin and further treatment is provided by ifitration through the sand-filled
chamber. Sand ifiters are particularly effective at removing suspended solids their associated
pollutants. Moderate removal of bacteria can be expected, but these systems cannot provide
removal of soluble pollutants such as nitrogen.
Water Ouality 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. 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 structural
storm water quality controls as pretreatment devices. They can be fairly effective at removing
coarse sediments and floating wastes and can be used to pretreat runoff before it is discharged
to infiltration systems or detention facilities. In this way, some of the routine maintenance
required of structural controls, such as sediment removal and unclogging of outlet structures,
can be reduced. Water quality inlets also can serve to capture accidental spills or illegal
discharges that could potentially enter other treatment structures or surface waters.
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EXISTING CONTROLS IN FOUR MERRIMACK RIVER BASIN COMMUNITIES
This section reviews the existing regulatory, source, and structural controls implemented in four
communities in the Merrimack River basin. The four communities are:
• Lawrence
• Methuen
• Newburyport
• North Andover
The City of Lawrence is densely developed with only a few parcels on which new development
could occur (MVPC,1991). Since little future new development will occur, improvements in
storm water pollution control will primarily result from changes to the regulations that impact
redevelopment and substantial renovations and from improved source controls. In addition to
these considerations, Lawrence is primarily served by a combined sewer system. Combined
sewer pollution control is being addressed through the NPDES permitting program. However,
storm water runoff controls can assist in reducing CSOs by reducing runoff volumes and the
storm water pollutant load component of the combined sewer overflows.
Methuen is a moderately developed town, covering about 23 square miles of which
approximately 40 percent is developed. Residential development dominates the land uses within
the town, although there are smaller amounts of retail and industrial activity. The center of the
town is somewhat densely populated while the outlying areas are less developed, and are not
served by sewers. Management practices for storm water control would need to be reviewed
as to how well they address both new development and redevelopment projects.
Newburyport is a moderately developed city located at the mouth of the Merrimack River. Most
of the city is residentially developed, with commercial development located downtown and in
the vicinity of the Route 95 interchange. Industrial activity occurs along the waterfront and in
the industrial park near Route 1 on the Newburyport/Newbury line. Most of the city’s
developable land has been developed, with the exception of some parcels near the Artichoke
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Reservoir Watershed on the West Newbury border.
North Andover is primarily a residential community of which 25% is developed and another
24% is potentially developable (MVPC, 1991). Most of the developed area is in residential use,
while significant portions of the open land are in public, wetland, and agricultural use.
These communities were chosen because they represent a variety of levels of existing
development, perceived levels of environmental awareness, and water resources to be restored
or protected. The information contained in this section will be used as a basis for
recommendations that can be used by these and other municipalities in the Merrimack River
basin and elsewhere to improve control of storm water pollution.
Regulatory Controls
Land development is a major cause of increased problems related to storm water runoff—both
quantity and quality—in growing urban areas. Therefore, by controlling and directing land
development through existing and new regulations, communities can reduce the impacts of storm
water runoff. However, in practice, the level of control existing in a community is related to
the perceived need to control or prevent pollution in particular water resources, and the ability
or willingness of the responsible government agencies to use their authority.
As discussed earlier, communities can control development and its associated storm water runoff
problems through zoning. Most communities have residential, commercial, industrial, and other
zoning districts established that specify the types of development allowed and dictate
requirements for building density, setbacks, lot coverage, landscaping, and drainage.
Communities permit certain activities as a right in the zoning districts and. may also specify that
certain activities are allowed in specific zones under special permit review. In order for these
zoning districts to provide runoff pollution protection, however, they must be appropriate for
the types of nearby water resources. Changing zoning districts and requirements for each
district may, therefore, present opportunities to improve storm water runoff pollution control.
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The appropriateness of these changes, however, is very site specific.
The areas of local regulations that generally relate to runoff control and were reviewed for this
project are:
• Subdivision Regulations
• Special Permit and Site Plan Review
• Wetlands Protection
• Earth Removal
• Special Zoning Controls
Existing provisions of these regulations for each of the four communities are outlined in Table
5. These regulations can be used by local government entities to 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 these regulations that are important
for storm water control are described in the following paragraphs. These major aspects are used
to organize the matrices in Table 5 so that the specific provisions of the regulatory practices in
each of the four communities can be summarized.
Runoff Ouantity 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 control.
This can be accomplished through a number of requirements:
• Open Space : By maintaining specified levels of open space on a development
site, the total area of impervious surface is reduced and inifitration of
precipitation is increased. This leads to decreases in total pollutant dischaEge and
potential downstream erosion by reducing total and peak runoff flows.
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TABLE 5. EXISTING REGULATORY CONTROLS
SUBDIVISION
CONTROL
Lawrence
Methuen
Newbul7port
North Andover
Scope of Regulations
As required under MGL all
lots being subdivided come
under Subdivision
Regulations. Lots on an
accepted public way and
having sufficient frontage
are classified as “Approval
Not Required”
As required under MGL all
lots being subdivided come
under Subdivision
Regulations. Lots on an
accepted public way and
having sufficient frontage
are classified as “Approval
Not Required”
As required under MGL all
lots being subdivided come
under Subdivision
Regulations. Lots on an
accepted public way and
having sufficient frontage
are classified as “Approval
Not Required”
As required under MGL
all lots being subdivided
come under Subdivision
Regulations. Lots on an
accepted public way and
having sufficient frontage
are classified as “Approval
Not Required”
Runoff Quantity Control
Open Space
Post-Development
Flow Control
Runoff Recharge
- Requires due regard for
maintaining natural features
and open space
- None specified
- None specified
- 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 that efforts be
made to maintain natural
features and open space
- None specified
- None specified
- Requires that efforts be
made to maintain natural
features and open space
- Requires calculations
showing pm and post-
construction peak flows
and total volumes for 2,
10, and 100 year storms
- Requires that storm water
shall be recharged rather
than piped to surface
waters to the maximum
extent feasible
Solids Control
- None specified
- Requires the development
of a runoff control plan that
minimizes erosion
- None specified
- Requires the development
of an erosion control plan
both during and after
construction
Other Pollution Control
- None specified
- None specified
- None specified
- None specified
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TABLE 5 (Continued). EXISTING REGULATORY CONTROLS
SPECIAL PERMIT AND
SITE PLAN REVIEW
Lawrence
Methuen
Newburyport
North Andover
Scope of Coverage
Site Plan Review
Special Permit
- Required for all new
construction except 1 and 2
family residences
- Required for all uses
requiring a special permit
- Requirements depend on
district
- Required for
nonresidential buildings
over 5,000 ft 2 and two
buildings on sime lot
- Required for all uses
requiring a special permit
- Required for specific
listed uses
- Required in specially
designated waterfront zones
- Required for residential
use exceeding 9 units
- Required for new
industrial and commercial
uses
- Required for specific
listed uses
- Required for
development or additions
>2000 ft 2 except single
family dwellings
- Required for specific
listed uses -
Runoff Quantity Control
Open Space
Post-Development
Flow Control
Runoff Recharge
- None specified
- Requires drainage plan for
10 year storm
- Requires on-site
infiltration wherever
practical
- Review boards have the
authority to impose special
conditions for buffers and
planting strips
- None specified
- None specified
- Required boundary
landscaping equivalent to 5
ft’/lOO ft 2 of parking
- None specified
- None specified
- None specified
- Requires plan showing
drainage control structures
to eliminate increases in
peak and total flow from
2, 10, and 100 year storms
- Detailed hydrology study
including potential
downstream impacts
- None specified
Solids Control
- Requires the development
of an erosion control plan
& minimal grading
- None specified
- None specified
- None specified
Other Pollution Control
- None specified
- None specified
- None specified
- See special zoning
controls- Watershed
Protection District
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TABLE 5 (Continued). EXISTING REGULATORY CONTROLS
LOCAL WETLANDS
PROTECTION’
Lawrence
Methuen
Newburyport
North Andover
Scope of Regulations
- No local ordinance; State
standards (MGL Ch 131
Sec 40) apply
- Local wetland protection
bylaw; State standards
(MGL Cl i 131 Sec 40) also
apply 2
- No local ordinance; State
standards (MGL Cl i 131
Sec 40) apply
- Local wetland protection
bylaw; State standards
(MGL Ch 131 Sec 40) also
apply 2
Runoff Quantity Control
Open Space
Post-Development
Flow Control
Runoff Recharge
- Restrictions on amount of
tree cutting allowed
- Compensatory storage
must be provided for all
inland flood volume lost
within same reach of water
body
- Must provide drainage
calculations for the 10 and
100-year storms
- None specified
None in addition to state
standards
- None in addition to state
standards
- None in addition to state
standards
- Restrictions on amount of
tree cutting allowed
- Compensatory storage
provided for all inland
flood volume lost within
same reach of water body
- Must provide drainage
calculations for the 10 and
100-year storms
- None specified
- Provides for 25 ft no
disturb zone and 50 ft no
build zone
- Hydrologic analysis
required for mean annual
10 and 100-year storms
- No net increase in rate of
aunoff allowed
- Standards established for
long-term design and
operation of basins
- Infiltration, leaching
catch basins, and drainage
dry wells recommended.
1 Specific performance standards are established in the state regulations for each type of coastal and inland resource area. Communities must refer to regulations
(310 CMR 10) for guidance. The listed standards apply to all resource areas, as noted
2 These communities must also comply with the requirements of the Massachusetts Wetlands Protection Act. Requirements listed are contained in local
regulations. See Lawrence and Newburyport for state standards applying to these communities.
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TABLE S (Continued). EXISTING REGULATORY CONTROLS
LOCAL WETLANDS
PROTECTION
(Continued)’
Lawrence
Methuen
Newbwyport
North Andover
Scope of Regulations
- No local ordinance; state
standards (MGL Ch 131
Sec 40) apply
- Local wetlands protection
bylaw; state standards
(MGL Ch 131 Sec 40) also
apply 2
- No local ordinance; state
standards (MGL Ch 131
Sec 40) apply
- Local wetlands protection
bylaw; state standards
(MGL Ch 131 Sec 40) also
apply 2
Solids Control
- Agricultural maintenance
and improvement activities
must be in accordance with
SCS guidelines
- Utility lines permitted if
erosion control plans are
developed
- None in addition to state
standards
. Agricultural maintenance
and improvement activities
must be in accordance with
SCS guidelines
- Utility lines permitted if
erosion control plans are
developed
. Erosion control plan
required including
temporary and permanent
ground cover and specific
erosion control measures
Other Pollution Control
- Application of herbicides
to public and utility
structures must be in
accordance with USDFA
management plans
- Must provide an estimate
of pm. and post-
development water quality
conditions
- None in addition to state
standards
- Application of herbicides
to public and utility
structures must be in
accordance with USDFA
management plans
- Must provide an estimate
of pre and post-
development water quality
conditions
- Wetlands approved for
fill must be replaced or
restored in accordance with
state and local standards
Specific performance standards are established in the state regulations for each type of coastal and inland resource area. Communities must refer to regulations
(310 CMR 10) for guidance. The listed standards apply to all resource areas, as noted
2 These communities must also comply with the requirements of the Massachusetts Wetlands Protection Act. Requirements listed are contained in local
regulations. See Lawrence and Newbuiyport for state standards applying to these communities.
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TABLE S (Continued). EXISTING REGULATORY CONTROLS
EARTH REMOVAL
Lawrence
Methuen
Newburyport
North Andover
Type of Regulations
- Zoning Bylaw & Earth
Removal Bylaw
- Soil Removal Ordinance
- Building Regulations
- Zoning Bylaw
Exemptions
- Construction of a building
or road for which a permit
has been issued
- Approved subdivisions
- Projects with approved
building permits
- Normal farm, garden, and
orchard activities
- Public use, cemeteries,
roads, and utilities
- Construction with an
approved building permit
and for which a plan has
been filed with the Soil
Removal Board
- On-site road construction
- Waiver process for sites
< 1 acre or removal <500
cubic yards
- Removal incidental to on-
site development
- Less than 50 cubic yards
of soil to be removed
.
Runoff Quantity Control
Open Space
Post-Development
Flow Control
Runoff Recharge
- None specified
- None specified
- None specified
- Provide 100 foot natural
buffer to a public way or
wetland
None specified

- None specified
- None specified
- None specified
- None specified
- None specified
- Hydrogeologic study
required specifying
downstream impacts of
removal
- None specified
Solids Control
- The impact of removal on
runoff must be determined
- Determine effect of
removal on storm water
runoff
- Provide 100 foot natural
buffer to a public way or
wetland
- Describe potential impacts
to nearby surface waters
- The plan must be
approved by the Soil
Conservation Service if>
1 acre in size
- Siltation basins are
required
- No more than 5 acres of
soil removal can take place
at one time
Other Pollution Control
- None specified
- None specified
- None specified
- None specified
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TABLE 5 (Continued). EXISTING REGULATORY CONTROLS
SPECIAL ZONING
CONTROLS
Lawrence
Methuen
Ncwbui rport
North Andover
Runoff Quantity Control
Open Space
Post-Development
Flow Control
Runoff Recharge
- None specified
- None specified
- None specified
Planned Unit and Cluster
Cluster Development
- Minimum requirement of
30% open space
- Hydrologic analysis is
required before
development
Setback
- Setback requirement for
development near open
streams and the Merrimack
River
Floodplain District
- Development prohibited in
floodway unless no increase
in flooding can be proven
- None specified
Planned Residential and
Development Districts
Develonment
- Minimum requirement of
30% open space
Floodplain District
- No increase in flood
discharge in Zone A
- None specified
- Required minimum 30%
open space for planned
residential districts and
20% for planned
development districts
Special Protection District’
- Specifies protection zone
between 100 and 325 feet
of the high water mark
Floodolain District
- No development in
floodway unless no
increase in 100 yr flood
- None specified
Solids Control
- None specified
- None specified
- None specified
Special Protection District’
- Agricultural use allowed
only with proper controls
Other Pollution Control
- None specified
- None specified
Performance Standards
- Materials that could
contaminate a ninning
stream cannot be
discharged
Special Protection District’
- Nitrogen levels in
groundwater are less than
10 mgll at property line
- Determine phosphorus
concentrations
- Prohibits potential
pollution causing activities
LaKe LocnlcnewlcK watersuen
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Post-development Flow Control : Many development regulations require that peak
runoff conditions from a site be calculated before and after construction. These
requirements specify that the conditions after construction must reflect the
conditions before construction. This is typically accomplished through the use of
detention facilities, which can reduce peak runoff discharge rates, thereby
decreasing downstream erosion problems. Through these regulations the desired
outcome is specified but the approach for ensuring that outcome 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 the 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.
Solids Control
Regulations addressing solids control may take the form of requirements for implementing
erosion control practices during and after construction. 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. Most communities, therefore, have
requirements for implementing erosion control practices on construction sites. These
requirements are generally overseen and enforced by the Conservation Commission when
development occurs in or near wetland areas. Fewer communities have requirements for erosion
control after construction is complete.
Other Pollution Control
Land development increases the concentrations of nutrients, pathogens, oxygen demanding
substances, toxics, and salt in storm water runoff. Development regulations, therefore, could
be used to address some of these specific pollutants. These regulations might take the form of
special requirements for limiting nutrient export in special protection districts or setting
performance standards for known problem pollutants.
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Strengths and Weaknesses of Existing Regulations
The review indicates that none of the four communities surveyed in the study has a
comprehensive program in place to address storm water and NPS pollution. Instead, each
community addresses specific components of storm water management (i.e., soil erosion, flood
control, or wetlands protection) to varying degrees. Below is a general discussion of the
strengths and weaknesses of regulatory controls in the four communities. The controls
investigated include:
• Subdivision Control
• Special Permit and Site Plan Review
• Local Wetlands Protection
• Earth Removal
• Special Zoning Controls
Subdivision Control. As previously noted, Massachusetts law requires that, with the exception
of parcels having sufficient frontage on an accepted public way, all parcels being subdivided
must undergo subdivision review. The four communities reviewed for this project require some
level of storm water pollution control in the subdivision design and development process.
However, the level of control required varies from community to community. In the area of
runoff quantity control, all four communities have language encouraging the maintenance of open
space and natural features. No specific requirements for open space, however, are given. For
post-development flow control, Methuen and North Andover state specific design storms under
which flow must be controlled. North Andover, however, is the only community that recognizes
the importance of controlling smaller, more frequent storms rather than just the large storms that
cause flooding. North Andover, is also the only community requiring the use of on-site runoff
recharge to the “maximum extent feasible.” This requirement is not defined in terms of
performance standards, however. Solids control is addressed by Methuen and North Andover.
They require the development of a runoff control plan to minimize erosion during construction.
North Andover also requires that the erosion control plan address the issue of post-construction
runoff control. There are no additional provisions of the subdivision regulations in the
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communities designed to address additional pollutants, such as nutrients or toxics.
Special Permit and Site Plan Review. All of the communities investigated for this review
require special permits and a site plan review for certain specified developments. The
developments not falling under these regulations are generally the single family and smaller
nonresidential developments, including some types of agricultural activities. Within these permit
and review processes, communities do not generally address storm water runoff control.
Methuen and Newburyport require some landscaping on site; however, this is generally done for
aesthetic reasons rather than to maintain open space. Some requirements are also in place to
control post-development flow. The most comprehensive of these is in North Andover, where
developers are required to control runoff from the 2, 10, and 100-year storms and determine the
downstream impacts of development. Also, runoff recharge is required in Lawrence “wherever
practical.” Once again, this requirement is not defined in terms of performance standards.
Beyond these runoff quantity control measures, Lawrence requires the development of an erosion
control plan. Other pollutants, such as nutrients and toxics, are not controlled in any of the
communities by the special permit or site plan review processes.
Wetlands Protection. The Massachusetts Wetlands Protection Act covers all wetlands in the
state. However, communities have the option to implement wetlands protection bylaws that are
more stringent than the statewide regulation. The state regulations control activities in each type
of coastal and inland resource areas. The controls that apply across most or all of the different
resources provide runoff quantity control and solids control through specifications for pre- and
post-development flow control for the 10 and 100-year design storms and requirements for
erosion control plans. They also specify that the use of herbicides and fertilizers be in
accordance with state and federal laws. These statewide regulations provide a fairly complete
-level of control on the effects of development. However, some communities, such as Methuen
and North Andover, have instituted local wetlands protection bylaws to further protect wetland
resources. The regulations in Methuen do not provide additional storm water runoff pollution
controls. However, the regulations in North Andover address additional open space
requirements, hydrologic analyses, and controls on runoff rate. In addition, the North Andover
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wetlands protection bylaw recommends the use of specific types of infiltration facilities.
However, actual design standards or criteria are not specified.
Earth Removal. The communities reviewed for this project all have earth removal regulations
that specify requirements for approval of excavation activities. These regulations generally do
not apply to removal of small amounts of soil or for removal under some other permitted
conditions. The exemptions in Methuen are especially broad and include farm, garden, and
orchard activities, as well as public uses and cemeteries. In areas where earth removal
regulations do apply, there is typically little control of runoff quantity. There is a requirement
in Methuen that a 100-foot buffer be maintained between earth removal activities and a wetland.
Also, in North Andover, developers are required to determine the downstream impacts of the
removal activities. However, the maximum level of impact allowed is not specified. Solids
transport is the primary pollution problem associated with earth removal, and the communities
generally address this issue. All of the communities require that developers determine earth
removal activity impacts on downstream surface waters, although acceptable impacts are not
defined This is further strengthened in Newburyport where activities involving more than one
acre of soil removal must be approved by the Soil Conservation Service, and in North Andover
where no more than five acres of removal can occur at once.
Special Zoning Controls. In addition to the above regulations, communities can utilize special
zoning tools to help in controlling storm water pollution problems. These include planned unit
developments, cluster developments, special protection districts, floodplain districts, and
performance standards. In all the communities investigated, except Lawrence, special
development districts that require maintenance of 20 to 30 percent open space have been set up.
Also, in Methuen, Newburyport, and North Andover restrictions have been set on developments
in the floodway of the 100-year flood. Developments in these areas must show that there will
be no increase in flood levels. Solids control is generally not specifically provided by these
special zoning districts. The exception to this is the special protection district set up by North
Andover in the Lake Cochichewick watershed that does not allow agricultural activities unless
proper controls are in place. Some communities have also established tools to address other
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pollution problems, such as nitrogen and toxic control. Newburyport has developed a special
performance standard in the waterfront district that prohibits the discharge of a material that
could contaminate a running stream, although contamination is not defined in terms of specific
criteria. Also, in the Lake Cochichewick watershed in North Andover, special requirements for
the control of nitrogen and phosphorus are in place. These are the most comprehensive controls
for these nutrients in the communities reviewed for this project.
Source Controls
In addition to the regulatory controls outlined above, a review of municipal control practices was
èonducted in the four communities. These practices, which are shown in Table 6, can prevent
storm water runoff from contacting pollutants and reduce the level of dry weather pollutant
discharged to suthce waters. The purposes and relative effectiveness of each of these practices
were outlined in the previous section.
Strengths and Weaknesses of Existing Source Controls
All four communities reviewed for this project have implemented source control practices that
reduce the availability of pollutants, such as street sweeping, catch basin cleaning, and solid
waste management. However, the greatest variation in the municipal programs exists in the area
of roadway sanding and salting, which is reflected in the sand to salt ratio and the total annual
tons per mile of salt used. Little consideration appears to have been given to the water quality
effects of these practices. In addition, none of the communities has any program designed to
locate and eliminate illicit cross connections. These can be a major source of dry weather
pollution in highly developed urban areas or where combined sewer systems have been
separated.
36

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TABLE 6. EXISTING SOURCE CONTROLS
Lawrence
Methuen
Newburyport
North
Andover
STREET SWEEPING
Frequency
Equipment (number)
Once/2 days
on 30 major
streets and
once/week on
others
Mechanical (3)
Once/week in
downtown
and
once/year in
other areas
Mech (1)
Vacuum (3)
Twice/year
Mech (1)
Once/year
except Lake
Cochichewick
three/year and
downtown
twice/year
Mech (2)
CATCH BASIN CLEANING
Frequency
Equipment (number)
Once/year
Mechanical (I)
Clamp
Once/year
Mech (1)
Orange Peel
Twice/year
Once/year
Mech (1)
Orange Peel
FERTILIZER AND PESTICIDE
USAGE
None used
Fertilizer
used on town
ball fields
None used
Granular
fertilizer used
for sodding
ANIM AL WASTE REMOVAL
No Program
No Program
No Program
No Program
ILLICiT CONNECTION
IDENTIFICATION AND REMOVAL
No Program
No Program
No Program
No Program
SOLID WASTE MANAGEMENT
Residential
Commercial
Recycling Program
Once/week
Twice/week
Paper
Fall Leaves
Once/week
Private
collection
Paper
Once/week
Twice/week
None
Once/week
Once/week
Paper
Leaves/grass
ROADWAY SANDING AND
SALTING
Sand-Salt Ratio
Salt Used (Tons/Road Mile)
Special Reduced Use Zones
4:3
11
None
1:1
12
None
4:1
3.5
None
7:1
6
None
37

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Structural Controls
None of the communities investigated for this project require the use of specific structural
controls on a widespread basis. Structural controls implemented in these communities are
generally designed to meet some of the pre- and post-construction flow requirements of the
subdivision and zoning regulations. While these regulations do not require specific types of
controls, detention basins are typically used to ensure that post-construction flows equal pre-
construction flows for the design storm or storms. The Town of North Andover, however,
requires the use of structural practices in certain defined circumstances. As part of the wetlands
protection bylaws, infiltration structures are recommended. The zoning bylaw requires the use
of siltation basins if earth removal occurs. Also, there is a specific provision stating that proper
controls must be used for agricultural practices in the Lake Cochichewick watershed.
STRENGTHS AND WEAKNESSES OF IMPLEMENTATION
Site visits were conducted at selected projects in Lawrence, Methuen, and North Andover to
discuss storm water quality control issues with municipal officials. Regulatory and construction
issues relating to storm water quality were reviewed and inspections were conducted at selected
project sites. The evaluations considered compliance with regulatory requirements and
recommended improvements. Specific information and typical evaluation criteria for each site
are summarized in Table 7. The evaluations were conducted considering flood control, storm
water quality, and general site development.
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TABLE 8. SITE EVALUATION SUMMARY
Crescent
Circle
Worcester
Street
Griffin
Brook Park
Coventiy
Estates
New Castle
Estates
N. Andover
Estates
SITE FEATURES
Location
Development Type
Topography
Year Constrocted
Lawrence
Residential
Hilly
1990
Methuen
Residential
Hilly
1989-1991
Methuen
Industrial
Flat
1980s
N. Andover
Residential
Hilly
1980s
N. Andover
Residential
Hilly
1991
N. Andover
Residential
Hilly
Under Const
DESIGN AND CONSTRUCTION FEATURES
Flood Control
Detention Used?
Retention Used?
Basin Operational?
Evidence of Overflow/Erosion?
Velocity Control?
Water Qua1ity Freatment
Grassed SwalesiFilter Strips?
Filter Berm/Extended Detention?
General Site Development/Erosion Control
Slopes Stabilized?
No
No
N/A
N/A
Yes
No
No
Yes
Yes
No
Yes
No
Yes
No
No
Yes
Not Evident
No
N/A
N/A
Yes
Yes
No
Yes
Yes
No
Yes
No
Yes
No
No
Yes
Yes
No
Yes
No
Yes
No
No
Yes
Yes
No
Under Const
Under Coast
Yes
Yes
Yes
Under Coast
N/A = Not Applicable
39

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Flood Control
Developers typically comply with storm water flood control requirements by utilizing detention
or retention basins. These basins contain the runoff for a particular storm event and either
release the water at a slow rate or allow the water to infiltrate into the groundwater.
Representatives of the communities acknowledged that flooding is a concern with existing and
new projects. Crescent Circle and Griffin Brook Industrial Park were the only projects which
did not include detention basins. No projects utilized retention basins for infiltration or runoff.
All the basins evaluated appeared to be operational with little evidence of overflow from the
containment berms. The Worcester Street project had excessive buildup of sediment and debris
in the bottom.
Runoff velocity controls prevent erosion and scouring and protect against downstream sediment
contamination. All the projects reviewed included controls to prevent erosion near drainage
outfalls. These controls vary from the use of a rip rap slope up gradient of the detention basin
for the Worcester Street project to the development of a rip rap velocity reduction basin for the
Crescent Circle project.
Storm Water Quality
Storm water quality protection has historically not been addressed by municipalities. North
Andover is the only community which has undertaken a concerted effort to improve the quality
of storm water discharge from new developments.
Only Griffin Brook Industrial Park and the North Andover Estates project included the use of
grassed swales and filter strips in the drainage design. The use of these controls in Griffin
Brook Industrial Park was likely a result of the need to address other environmental issues such
as flood plain management or erosion prevention. These controls also provide filtering of
sediments. The North Andover Estates project included these controls to allow for the filtering
of sediment and associated contaminants out of the runoff.
40

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The development of “extended detention” basins allows for the settlement of sediment and other
pollutants. This process involves restricting outflow from the basins for smaller storms such as
the one year event. EPA studies have shown that high levels (i.e., 90 percent) of the pollutants
in storm water runoff are captured by controlling smaller storm events. North Andover Estates’
detention basin includes a baffle to extend the detention time for the runoff in the basin, but does
not include detaining the one-year storm event. None of the other basins were designed to
detain such smaller storms. Many of the basins had evidence of sediment buildup in the streams
or wetlands down-gradient of the outlet. This buildup indicates that the debris is not settled out
in the basin but is passed through the outlet.
General Site Development
Projects have typically included some means to control runoff and sediment during construction.
These measures were probably included to conform to the requirements of the Wetlands
Protection Act; local officials; or for safety or aesthetic reasons. All the projects have stabilized
slopes and some still have erosion controls in place. While the use of the erosion controls and
slope stabilization techniques has not been driven primarily by water quality issues, they do
generally offer protection from sediment contamination.
RECOMMENDED IMPROVEMENTS
Based on the review of regulatory and source control practices implemented in four communities
in the Merrimack River basin, some general conclusions can be reached about storm water and
NPS pollution control practices. None of the communities investigated has systematically used
its existing regulations to prevent storm water and NPS control problems, although North
Andover has made the best attempt. The communities all have regulations that, jf strengthened,
could provide improved pollution control. However, these regulations have been developed over
a number of years and have had purposes largely unrelated to runoff pollution control.
Therefore, they need to be reexamined in light of their ability to control storm water runoff and
NPS pollution. Community source control practices appear generally adequate, except for
41

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exercising caution by limiting use of salt for deicing, and developing a program to remove cross-
connections and illegal discharges. Below are some of the more important recommendations for
strengthening the regulatory and source controls investigated for this project.
Regulatory Controls
The following measures that would result in more effective control of storm water and NPS
pollution of surface waters:
Site plan, special permit, and subdivision criteria should be more specific with regard to
proper storm water runoff control in the areas of open space, post-development flow
control, and solids control. The criteria could be presented in the form of a checklist
that the special permit granting authority or planning board could use to insure that each
new development or redevelopment is meeting appropriate standards. Among the criteria
that could be included are:
Open Space
• Requirement of a minimum 100-foot vegetated buffer to any surface water body
or wetlands area (Pitt, 1991 - Quoted from Birmingham Proposed Watershed
Protection Ordinance). Size of the buffer can be related to the size of the
development. A 100-foot buffer may not be appropriate for a small parcel.
• Requirement for designs including “disconnected impervious areas” such as the
following:
- roof drains discharge to pervious areas
- driveways slope to pervious areas
- elimination of curbs where they are not needed to allow runoff to flow
overland to pervious areas
Post-Development Flow Control
• Requirement for control of runoff from the 2 and 10 year storm events, such that
post-development peak and total flows are no greater than pre-development peak
and total flows (Pitt, 1991 - Quoted from State of Maryland Model Stormwater
42

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Management Ordinance). A smaller storm, such as a 1-inch depth rainfall event,
should also be included.
Runoff Recharge
• Requirement for onsite recharge on sites with groundwater more than four feet
below the bottom of the recharge structure and soils with infiltration rates greater
than or equal to 0.27 in/hr (Washington State Department of Ecology, 1991).
On-site recharge can be defined as a percentage of runoff volume from a design
event (i.e., recharge 90% of the runoff from a two-year storm).
Solids Controls
• Requirement for preparation of an erosion control plan that addresses control of
both temporary construction and long-term runoff. Based on requirements in other
communities, the plan should include the following:
- location of areas to be stripped of vegetation and other exposed or
unprotected areas
- a schedule of operations to include starting and completion dates for major
development phases, such as-land clearing and grading, street, sidewalk,
and utility installation, and sediment control measures
- specifications for diverting water from upsiope areas so it does not flow
over disturbed land
- seeding, sodding, or revegetation plans and specifications for all
unprotected or unvegetated areas
- location and design of structural sediment control measures, such as
diversions, grade stabilization structures, debris basins, etc.
- information relating to the implementation and maintenance of the
sediment control measures
Other Pollution Control
• Specific standards should be developed where particular pollutants are known to
cause pollution problems. This is a community-specific issue that is a function
of the particular water resources being protected.
2. Consistent standards should be applied across regulations, where possible. For example,
baseline design storm requirements should be the same for required calculations in
subdivision, special permit, earth removal, and wetlands protection regulations. In Table
5, good criteria used in one regulation were often not applied as part of other regulations,
43

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although they were applicable.
3. Specific requirements should be set for periodic post-construction inspection of a site.
Inspections should be conducted after at least one major storm event per year (Maryland
DNR, 1985). The post construction inspections should be done by staff of the town or
by the agent of the planning board or special permit granting authority at the expense of
the developer. The fees for these inspections should be added to the fees normally
assessed to the developer during the review and construction phases of the project. Post
construction inspections and resulting maintenance are critical to the performance of
storm water facilities’ ability to remove pollutants.
4. For those communities that have nonresidential development situated adjacent to critical
water bodies, overlay districts should be implemented for the protection of water quality.
Any new or substantial rehabilitation of nonresidential activities should be required to
obtain a special permit. The requirements of the special permit must be designed to
protect the type of water body in each of the overlay districts, and thus there might be
slightly different discharge limitations depending on whether the water body is a wetland,
a low- flow stream, a fast- flowing river, or a recreational lake. Development of new
residential or nonresidential activities should be curtailed in areas adjacent to drinking
water bodies.
5. The types of exemptions for special permit, site plan review, or earth removal should be
narrowed. For example, in many communities agricultural activities are exempt from
review. However, all commercial agricultural activity, any residential agricultural activity
greater than 5000 square feet of a surface water body should be subjected to special
review and standards. for limiting the amount of nutrients added to soil (Pitt, 1991 -
Quoted from State of Maryland statewide storm water control regulations). Any earth
removal activity of over 2000 sf or greater than 400 cy should undergo special permit
review (Pitt, 1991 - quoted from Proposed Birmingham Watershed Protection
Ordinance). For those activities that would remain exempt, a set of standard storm water
44

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control practices should be added to that part of the zoning bylaw authorizing such
activity. These standards should include requirements for maximum slope, revegetation,
and prohibitions on any direct discharge to any surface water body or to adjacent
properties. Water quality impacts could be caused by the cumulative effects of small
development that is currently exempt from most of the existing controls.
6. The standard storm water control provisions noted above in Item 3 should also be made
applicable to those projects filing for “Approval Not Required” under the Subdivision
Control Law. The developer would not be required to submit a preliminary or definitive
plan as required for those projects requiring subdivision approval, however, the
developer would be required to comply with standard erosion and runoff control
measures.
7. A requirement for preparation of an Environmental and Community Impact Analysis
should be incorporated into subdivision control regulations. Based on requirements in
other communities, any submission of a residential subdivision creating over 15 lots, and
all non-residential subdivisions, should be accompanied by such an Impact Analysis. The
Planning Board may require that the analysis be conducted for smaller residential
subdivisions, if the proximity to sensitive resources warrants it. Among the issues
addressed in the Impact Analysis should be Water Quality. The impact of storm water
run-off on adjacent and downstream surface water bodies and sub-surface ground water
should be evaluated. The evaluation should address the dangers of flooding as a result
of increased downstream runoff, especially peak runoff; the potential for downstream
water quality degradation; and the potential for short-and long-term erosion. The impact
analysis must address the direct and indirect water quality impacts, and must identify
measures to be used to minimize any adverse water quality impacts. The state water
quality standards can serve as performance standards for assessing water resource
impacts.
45

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SUM1 1ARY OF ASSESSMENT PROCEDURE
Land development in communities is one of the primary causes of storm water and NPS
pollution problems. These problems can, however, be difficult to address once water resources
have been affected. Therefore, it is more appropriate and effective for communities to prevent
these pollution problems through efforts to control and guide land development. Since
municipalities generally develop regulations and undertake source control practices for reasons
other than runoff pollution control, improvements may be made by assessing current regulations
and source control practices for their ability to address these runoff pollution problems.
This section outlines the steps that can be used to assess and strengthen runoff pollution controls.
This assessment emphasizes implementing regulatory and source control practices as a first step
in addressing storm water runoff and NPS pollution problems. In order to implement a more
complete program involving retrofitting specific structural control practices in existing
developments, a more complex and time-consuming process must be undertaken. The steps in
this regulatory and source control review process include:
• Investigate Existing Regulatory and Source Control Measures
• Investigate Recent Land Development Projects
• Determine Water Resources
• Strengthen Controls
Investigate Existing Regulatory and Source Control Measures
Few communities have implemented comprehensive storm water pollution control ordinances
because of the lack of recognition that storm water can be a pollution problem, the difficulties
inherent in developing such regulations, and potential duplication of effort with other existing
regulations. In order to strengthen existing regulations and practices, it is necessary to first
summarize the aspects of existing regulations and source controls that address storm water runoff
pollution. Existing regulations should be summarized in a matrix similar to Table 5 in this
report. The regulations that should be investigated include:
46

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• Subdivision Regulations
• Special Permit and Site Plan Review Procedures
• Wetlands Protection
• Earth Removal
• Other Special Protection Regulations
- Special Protection Districts
- Planned Residential and Development Districts
- Cluster Developments
- Floodplain Districts
- Performance Standards
These regulations can be used to reduce storm water runoff pollution through the maintenance
of open space, control of post-development flow, recharge of runoff, control of solids
discharges, and control of other pollutants. For other Merrimack River basin and Massachusetts
communities, a comparison can be made with the four communities summarized in this report.
Developing a matrix with this information can allow a community to identify the areas of control
that may be weak. For example, the communities investigated for this project generally have
regulations that control peak runoff rates from large storms. However, since runoff pollution
is primarily the result of smaller storms, little quality control is provided. Also, few of the
regulations existing in these communities provide specifications and criteria for the construction
and maintenance of structural control practices.
A similar matrix can be developed for outlining existing source control practices (see Table 6).
The practices that should be included in this review include:
• Street Sweeping
• Catch Basin Cleaning
• Fertilizer and Pesticide Usage
• Animal Waste Removal
• illicit Connection Identification and Removal
• Solid Waste Management
• Roadway Sanding and Salting
• Important considerations include the frequency of actions and the conditions under which the
actions are taken. Most communities conduct these activities to maintain the aesthetic qualities
47

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of an area, with runoff pollution control being a secondary consideration. In the areas of street
sweeping, catch basin cleaning, and solid waste management, frequencies that maintain the
aesthetic qualities of an area are typically sufficient to address some of the runoff pollution
control considerations. However, reduced roadway sanding and salting and illicit connection
identification and removal may be controls that a community does not currently undertake that
could be valuable in reducing storm water runoff pollution. The development of a matrix
outlining this information can help the community more fully identify the areas of potential
improvement.
Investigate Recent Land Development Projects
Investigating existing development regulations can indicate the areas where storm water runoff
pollution control is weak. However, in order to fully assess existing regulatory controls, the
implementation of these controls at recent developments can be investigated. Communities
should investigate developments that have gone through the existing regulatory reviews in the
past few years. Conducting site visits can indicate how well the existing regulations are being
implemented. This is the true test of the effectiveness of regulations and the review process.
Site investigations should be conducted with the existing regulations serving as a guide. Factors,
such as on-site structural controls, percent open space, erosion controls, and landscaping
features, as ouffined in Table 7, should be considered. Other than the existence of structural
controls, the site should be evaluated to determine whether maintenance is being performed.
Structural controls designed to reduce pollutant discharges become less effective as sediment
accumulation, vegetative growth, and outlet clogging occur. Regular maintenance of the controls
is necessary to ensure that they continue functioning as designed.
A site evaluation matrix, similar to that shown in Table 7, can be utilized in the review of recent
developments. Areas of discrepancy between regulatory requirements and actual implementation
can indicate a failure to properly enforce existing controls. These can be addressed through
improved education of review board members or increased requirements for plan submission.
However, if a site has problems beyond those typically controlled by regulations, the community
48

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may be required to strengthen existing controls. In either case, a number of sites should be
investigated on a regular basis to ensure that regulations are providing a sufficient level of runoff
pollution control.
Assess Water Resources
The level of storm water and NPS pollution control required in a community is influenced by
the existing water resources. For example, protection of a surf ce water drinking supply is more
critical than protection of a small urban creek. Therefore, in this step, communities should
make a determination of existing water resources and their value. Information should be
gathered on the existing conditions throughout the watershed and in the water body. Watershed
information includes land use, topography, soil type, and other physical features. In addition,
water quality and sediment quality data should be compared to classification standards and
criteria to give an indication of the quality of the resource. The information required for a
watershed and receiving water review are:
• Watershed Data Description
- Environmental Data
- Infrastructure Data
- Municipal Data
- Potential Sources/Existing Pollution Control Data
- Miscellaneous Data
• Receiving Water Data Description
- Physical/Hydrologic Data
- Chemical Data
- Biological Data
- Water Quality Standards and Criteria
- Miscellaneous Data
• Summary of Data Gaps and Needs
These data can impact the level of benefit expected from implementing controls, and are
necessary for a community to be able to make specific changes to regulatory and source control
practices.
49

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Strengthen Controls
Once existing regulatory and source control practices have been reviewed, implementation of
those regulatory control practices has been investigated, and the water resources in the
community have been assessed, the regulatory and source control practices can be strengthened.
In this step, recommendations, similar to those outlined in the previous section, can be
implemented. This involves analyzing each regulatory control practice to determine the potential
level of control it can provide. Consideration must be given to the scope of the regulations.
In some cases, existing regulatory control is not provided and new regulations, such as overlay
zones, performance standards, or special protection districts, will have to be developed.
However, in other cases, existing subdivision, zoning, or earth removal regulations will only
have to be strengthened to address an identified problem. In addition, the water resources
existing in a community will impact the level of control desired. More comprehensive controls
will be required in a surface water supply watershed than in an urban stream watershed. Issues
that must be considered in this step include the authority and the ability of local review boards
to implement some regulations, input from the regulated public (including support and
opposition), and budget restriction. However, the assessment process, which reveals existing
weaknesses and identifies key resources for protection, will allow communities to establish
priorities for implementing necessary storm water control measures.
50

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REFERENCES
Florida Department of Environmental Regulation, 1992. “The Florida Development Manual:
A Guide to Sound Land and Water Management.”
Maryland Department of Natural Resource, Water Resources Administration, Sediment and
Stormwater Division, 1985. “Inspector’s Guide Manual for Stormwater Management
Inifitration Practices.”
Morehouse, Robert, 1988. “Ready Reference Guide to Non Point Source Pollution; Sources,
Pollutants, Impairments; Best Management Practices for the New England States,”
detailed from U.S.D.A. Soil Conservation Service to U.S. EPA, Region I.
Merrimack Valley Planning Commission, 1991. “A Survey of Urban Runoff Programs in
Selected Communities in the Merrimack Valley Region.”
Minnesota Pollution Control Agency, 1989. “Protecting Water Quality in Urban Areas.”
Pitt, R., 1991. “Source Loading and Management Model: An Urban Nonpoint Source Water
Quality Model. Volume I: Model Development and Summary.”
Pitt, R., M. Lalor, M. Miller, G. Driscoll, 1990. “Assessment of Non-Stormwater Discharges
into Separate Storm Drainage Systems. Draft.” Storm and Combined Sewer Control
Program, US EPA.
Schueler, T.R, 1987. “Controlling Urban Runoff: A Practical Manual for Planning and
Designing Urban BMPs.” Metropolitan Washington Council of Governments Publication
87703.
Urban Land Institute. 1981. “Water Resource Protection Technology: A Handbook of
Measures to Protect Water Resources in Land Development.”
US EPA. 1974. “Urban Storm Water Management and Technology: An Assessment.”
51

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REFERENCES (Continued)
United States Environmental Protection Agency, 1987. “Guide to Nonpoint Source Control.”
United States Environmental Protection Agency, 1992. “Coastal Nonpoint Source Control
Program: Management Measures Guidance - Draft.”
United States Environmental Protection Agency, Center for Environmental Research
Information, 1992. “Planning Process for Storm Water and Nonpoint Source Control -
Draft.”
Washington State Department of Ecology, 1991. “Storm Water Management Manual for the
Puget Sound Basin.”
52

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APPENDIX A

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G.n.ral Effectiven... of Various Nonstructural Control Practices
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(continued)
III. SITE PLANNING
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Sourc•: Metropolitan Washington Council of Gov•rnments, 1991 (Draft)

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Comparative Pollutant Removal Of Urban BMP Designs
FILTER STRIP
GRASSED SWALE
DESIGN 10
DESIGN II
DESIGN 12
DESIGN 13
DESIGN 14
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MODERATE
MODERATE
lION
MODERATE
MODERATE
NIGH
MODERATE
HIGH
NIGH
LOW
LOW
MODERATE
LOW
LOW
1 1EV;
o
(3 20T040%REMOVAL
J 4OT000SREMOvAL
•OTOIO%REMOVAL
•
( INSUFFICIENT
KNOWLEDGE
Design 1: First-flush runoff volume detained for 6-12 hours.
Design 2: Runoff volume produced by 1.0 inch, detained 26 hours.
Design 3: As in Design 2, but with shallow marsh in bottom stage.
Design 4: Permanent pool equal to 0.5 inch storage per impervious acre.
Design 5: Permanent pool equal to 2.5 (Vr); where Vrmean storm runoff.
1i sign 6: Permanent pool equal to 6 0 (Vr); approx. 2 weeks retention.
Design 7 Facility exfiltrates first-flush; 0.5 inch runoff/;mper. acre.
Design 8: Facility exfiltrates one inch runoff volume per l eper. acre.
Design 9: Facility exfiltrates all runoff, up to the 2 year design Storm.
Design 10: 600 cubic feet wet storage per impervious acre.
Design 11: 20 foot wide turf strip
Design 12: 100 foot wide forested strip, with level spreader.
Design 13: High slope swales, with no check dams.
Design 14: Low gradient swales with check dams.
Source: Shueler, 1987
BMP/design
EXTENDED DETENTiON POND
DESIGN I
DESIGN Z
DESIGN 3
WET POND
• ( 3) ®
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DESIGN 4
DESIGN 5
DESIGN a
INFILTRATION TRENCH
DESIGN 7
DESIGN S
DESIGN S
INFILTRATION DASIN
•)) •
DESIGN 7
DESIGN S
DESIGN S
POROUS PAVEMENT
• •••
MODERATI
HIGH
NIGH
DESIGN 7
DESIGN S
DESIGNS
WATER OUALITY INLET
• . ••

MODERATE
HIGH
HIGH
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-------