&EPA
United States
Environmental Protection
Agency
2012 GREEN INFRASTRUCTURE TECHNICAL ASSISTANCE PROGRAM
Town of Franklin, Massachusetts
Green Infrastructure Implementation Strategy TO
the Town of Franklin, Massachusetts
An Evaluation of Projects, Programs, and Policies
Photo: Town of Franklin
EPA EP-C-11-009
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About the Green Infrastructure Technical Assistance Program
Stormwater runoff is a major cause of water pollution in urban areas. When rain falls in undeveloped
areas, the water is absorbed and filtered by soil and plants. When rain falls on our roofs, streets, and
parking lots, however, the water cannot soak into the ground. In most urban areas, stormwater is
drained through engineered collection systems and discharged into nearby waterbodies. The
stormwater carries trash, bacteria, heavy metals, and other pollutants from the urban landscape,
polluting the receiving waters. Higher flows also can cause erosion and flooding in urban streams,
damaging habitat, property, and infrastructure.
Green infrastructure uses vegetation, soils, and natural processes to manage water and create healthier
urban environments. At the scale of a city or county, green infrastructure refers to the patchwork of
natural areas that provides habitat, flood protection, cleaner air, and cleaner water. At the scale of a
neighborhood or site, green infrastructure refers to stormwater management systems that mimic
nature by soaking up and storing water. These neighborhood or site-scale green infrastructure
approaches are often referred to as low impact development.
EPA encourages the use of green infrastructure to help manage stormwater runoff. In April 2011, EPA
renewed its commitment to green infrastructure with the release of the Strategic Agenda to Protect
Waters and Build More Livable Communities through Green Infrastructure. The agenda identifies
technical assistance as a key activity that EPA will pursue to accelerate the implementation of green
infrastructure.
In February 2012, EPA announced the availability of $950,000 in technical assistance to communities
working to overcome common barriers to green infrastructure. EPA received letters of interest from
over 150 communities across the country, and selected 17 of these communities to receive technical
assistance. Selected communities received assistance with a range of projects aimed at addressing
common barriers to green infrastructure, including code review, green infrastructure design, and cost-
benefit assessments. The Town of Franklin was selected to receive assistance to quantify the benefits of
existing green infrastructure projects, identify green infrastructure barriers and opportunities in the
Town's local codes, and develop a green infrastructure implementation strategy for the Town.
For more information, visit http://water.epa.gov/infrastructure/greeninfrastructure/gi support.cfm.
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Acknowledgements
Principal USEPA Staff
Ray Cody, USEPA Region I
Tamara Mittman, USEPA
Christopher Kloss, USEPA
Community Team
Brutus Cantoreggi, Town of Franklin DPW
Michael Maglio, Town of Franklin DPW
Consultant Team
Michelle West, Horsley Witten Group, Inc.
Rich Claytor, Horsley Witten Group, Inc.
Jennifer Reiners, Horsley Witten Group, Inc.
Stephen Kasacek, Horsley Witten Group, Inc.
Katie Lamoureux, Horsley Witten Group, Inc.
John Kosco, Tetra Tech, Inc.
Photos used in the report are credited to the Horsley Witten Group, Inc. unless otherwise noted.
This report was developed under EPA Contract No. EP-C-11-009 as part of the 2012 EPA Green
Infrastructure Technical Assistance Program.
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Contents
1.0 Introduction
1.1 Purpose 1-1
1.2 What is Green Infrastructure? 1-1
1.3 Benefits of Green Infrastructure in Franklin 1-3
1.4 Implementing Green Infrastructure: Projects, Programs, and Policies 1-7
1.5 Franklin's Green Infrastructure Goals and Objectives 1-7
2.0 Projects
2.1 Bioretention/Green Streets 2-1
2.2 Infiltration Practices 2-5
2.3 Rain Harvesting 2-7
2.4 Permeable Pavement 2-9
2.5 Constructed Wetlands 2-11
2.6 Green/Blue Roof Practices 2-14
2.7 Non-structural Practices 2-16
3.0 Programs
3.1 Education 3-1
3.2 Community Planning and Development 3-2
3.3 Operations and Maintenance 3-4
4.0 Policies
4.1 Regulatory Drivers 4-1
4.2 Policy Review and Recommendations 4-2
5.0 Implementation Recommendations
5.1 A Vision for Green Infrastructure Implementation 5-1
5.2 Specific Recommendations for Implementing Projects, Programs, and Policies... 5-1
6.0 References
Attachment 1 - Quantification of Benefits from Existing Green Infrastructure Projects - Town
of Franklin, MA, 2013
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Figures
Figure 1-1. Elements of Green Infrastructure 1-2
Figure 1-2. Examples of Gray and Green Infrastructure 1-3
Figure 1-3. Map of Upper Charles River Watershed 1-4
Figures l-4a-d. Benefits of Green Infrastructure 1-6
Tables
Table 1-1. Cost of Phosphorus Removal for Six Town of Franklin Projects 1-5
Table 1-2. Green Infrastructure Projects, Programs and Policies 1-7
Table 1-3. Goals and Objectives for the Town of Franklin's Green Stormwater
Infrastructure Implementation 1-8
Table 2-1. Descriptions of Bioretention/Green Street Practices 2-2
Table 2-2. Guidance for Implementation of Bioretention/Green Street Practices 2-4
Table 2-3. Descriptions of Infiltration Practices 2-5
Table 2-4. Guidance for Implementation of Infiltration Practices 2-7
Table 2-5. Descriptions of Rain Harvesting Practices 2-8
Table 2-6. Guidance for Implementation of Rain Harvesting Practices 2-9
Table 2-7. Descriptions of Permeable Pavement Practices 2-10
Table 2-8. Guidance for Implementation of Permeable Pavement Practices 2-11
Table 2-9. Descriptions of Constructed Wetland Practices 2-12
Table 2-10. Guidance for Implementation of Constructed Wetlands 2-13
Table 2-11. Descriptions of Green/Blue Roof Practices 2-14
Table 2-12. Guidance for Implementation of Green/Blue Roof Practices 2-15
Table 2-13. Descriptions of Non-Structural Practices 2-16
Table 2-14. Guidance for Implementation of Non-Structural Practices 2-18
Table 3-1. Descriptions of Proposed New Education Programs 3-2
Table 3-2. Descriptions of Proposed New Community Development Programs 3-4
Table 3-3. Descriptions of Proposed New O&M Programs under the Engineering
Division 3-5
Table 3-4. Descriptions of Proposed New O&M Programs under the Highway Division 3-6
Table 3-5. Descriptions of Proposed New O&M Programs under the Water and
Sewer Division 3-8
Table 3-6. Descriptions of Proposed New O&M Programs under the Recycling and Solid
Waste Division 3-9
Table 3-7. Descriptions Proposed New O&M Programs under the Parks and Grounds
Division 3-9
Table 3-8. Proposed New O&M Programs underthe Facilities Department 3-10
Table 5-1. Example Format for Prioritizing Identified Opportunities to Strengthen
Green Infrastructure in the Town of Franklin 5-3
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1.0 Introduction
1.1 Purpose
The Town of Franklin is seeking to improve local water quality, as well as preserve and recharge
groundwater resources while also saving money, by implementing green infrastructure in Town
and private projects. The Town already has a history of utilizing green infrastructure in certain
road and stormwater projects where possible, but would like to expand their use through the
development of a Town-wide implementation strategy. This document is intended to help the
Town of Franklin develop a comprehensive strategy for implementing green infrastructure
through practices, programs, and policies. It summarizes the Town's existing efforts, provides
recommendations for improving existing programs and policies, and proposes new approaches
for incorporating green infrastructure. Each section highlights techniques that are best suited
for the Town, based on the Town's land uses and physical constraints, their experience with the
implementation of existing practices, and the findings of recently completed reviews of the
Town's current programs and
policies.
1.2 What is Green Infrastructure?
"Green infrastructure is a network of decentralized
stormwater management practices, such as green roofs,
trees, rain gardens and permeable pavement, that can
capture and infiltrate rain where it falls, thus reducing
stormwater runoff and improving the health of surrounding
waterways (CNT, 2010)."
The term "green infrastructure,"
which is thought to have originated
sometime in the mid-1990s, can
mean different things to different people. For example, some may refer to trees in an urban
environment as green infrastructure because of the "green" or environmental benefits they
provide, while others use the term to refer to an interconnected network of green spaces
(Benedict and McMahon, 2001). The US Environmental Protection Agency (US EPA) and
many other environmental organizations today use the term green infrastructure to refer to
engineered systems, such as rain gardens or green roofs, which are designed to maintain
natural hydrologic functions, and mitigate the impacts of development on the environment.
Some of these similar definitions are provided in the call-out boxes. For the purposes of this
report, green infrastructure is similarly defined as a network of decentralized stormwater
management practices, such as rain gardens, bioretention systems, and green roofs that can
capture, infiltrate and treat stormwater thereby reducing stormwater runoff and improving the
health of receiving waters.
"Green Infrastructure refers to natural systems that capture, cleanse and reduce stormwater
runoff using plants, soils and microbes. On the regional scale, green infrastructure consists of
the interconnected network of open spaces and natural areas (such as forested areas,
floodplains and wetlands) that improve water quality while providing recreational
opportunities, wildlife habitat, air quality and urban heat island benefits, and other community
benefits. At the site scale, green infrastructure consists of site-specific management practices
(such as interconnected natural areas) that are designed to maintain natural hydrologic
functions by absorbing and infiltrating precipitation where it falls (CWP, 2013)."
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"Green infrastructure is an approach that communities can choose to maintain healthy
waters, provide multiple environmental benefits and support sustainable communities.
Unlike single-purpose gray storm water infrastructure, which uses pipes to dispose of rainwater,
green infrastructure uses vegetation and soil to manage rainwater where it falls. By weaving
natural processes into the built environment, green infrastructure provides not only
stormwater management, but also flood mitigation, air quality management, and much more
(US EPA, 2013)."
Habitat
Green
Infrastructure
Figure 1-1. Elements of Green Infrastructure (EPA, 2013)
One way to conceptualize green infrastructure is to think about it as an alternative to
conventional or "gray" infrastructure (see Figure 1-2). Gray infrastructure is what we often
think of when we hear the word infrastructure: roads, pipes, sewers, utility lines, etc.
Traditional gray stormwater infrastructure consists of a system of concrete curbs, gutters,
pipes, tanks, outfalls, and other engineered systems intended to capture and convey
stormwater and discharge it offsite, typically to a nearby surface water. Although these
systems provide local flood control, they usually provide little if any treatment or groundwater
recharge and can cause significant environmental damage to receiving waters through the
introduction of pollutants, erosion, flooding, and warming. These impacts can be detrimental
to the aquatic species living in the waterbodies as well as their recreational and public health
benefits. In fact, stormwater runoff is the number one cause of stream impairment in urban
areas (CWP, 2013).
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Figure 1-2. Examples of Gray (top) and Green (bottom) Infrastructure
To mitigate the impacts of stormwater runoff on receiving waters, many communities have
transitioned from gray infrastructure to green infrastructure. As a result of converting from
"gray to green," these communities have seen improvement in their waterbodies. They have
also experienced additional, sometimes unforeseen benefits, such as greater wildlife
biodiversity, increased green space available for the public to enjoy, and even increased
property values (CNT, 2010). The next section will describe how Franklin, specifically, has
already started to benefit from green infrastructure, and how a comprehensive green
infrastructure strategy could further these benefits.
1.3 Benefits of Green Infrastructure in Franklin
To fully examine the potential benefits of green infrastructure in Franklin, it is important to first
provide the context of the existing conditions of its water resources. The Town of Franklin is
located within the Charles River Watershed, and its municipal separate storm sewer (MS4)
discharges contribute to the existing impairments in the Charles River. The primary pollutant of
concern is phosphorus, a nutrient found in stormwater runoff originating in fertilizers, animal
waste, and other sources. The Charles River has been plagued by algal blooms in recent years
as a result of stormwater-associated phosphorus loading. These algal blooms threaten
recreational use of the river and degrade fish habitat and aesthetics. EPA's goal is to reduce
phosphorus discharges to the lower Charles by 54% to restore the river to a healthier ecological
state and has set load reduction targets for each town in the watershed as a part of the Charles
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River Total Maximum Daily Load (TMDL). In an effort to help the towns meet the TMDL, the
EPA has issued a Draft General Permit under the Residual Designation Authority (RDA) of the
federal Clean Water Act (CWA) for three pilot communities in the watershed (Franklin along
with Milford and Bellingham) that would ultimately require certain industrial, commercial, and
high-density residential facilities to take measures to reduce phosphorus loading from
stormwater discharges.
Legend
Q3 Watersheds
>/\y~ Charles River
Streams
Ponds
^_\__ f_ \^MILE \
Figure 1-3. Map of Upper Charles River Watershed
In an effort to ameliorate the impacts of stormwater runoff and associated phosphorus
pollution on receiving waters, the Town of Franklin has already installed a number of green
infrastructure projects. Six of these projects are highlighted in Attachment 1 (Quantification of
Benefits from Existing Infrastructure Projects- Town of Franklin, 2013). Overall, these projects,
which include bioretention, infiltration basins, rain gardens, pavement reduction, and
application of zero-phosphorus fertilizer, remove a total of about 76 pounds of phosphorus per
year (Table 1-1). The implementation of additional green infrastructure projects will further
reduce phosphorus loading to the Charles River and other receiving waters improving the
health of these waters.
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Table 1-1. Cost of Phosphorus Removal for Six Town of Franklin Projects
Project Name
Lockewood Drive
Panther Way
Wachusett
Street
Wyllie
Road/ Miller
Street
Small Fletcher Lot
Parmenter School-1
Parmenter School-2
Miller at Green
Wyllie Rd
Greensfield Road
Town Property - P-free Fertilizer
Total:
Type of
BMP(s)
Bioretention,
Infiltration
Basin
Infiltration
Basin
Bioretention
Bioretention
Bioretention,
Infiltration
Chambers
Bioretention,
Infiltration
Chambers
Infiltration
Chambers
Rain Garden,
Pavement
Reduction
Phosphorus-
free
Fertilizer
NA
TP
Reduction
(Ib/yr)
7.90
15.45
0.65
0.53
1.40
11.72
4.26
0.29
34
76.2
Project
Cost
$13,000
$75,388
$71,612
$122,000
$112,289
-$10,000
-$5,978
$378,311
Cost of TP
Reduction
($/lb/yr)
$1,645
$4,880
$27,768
$10,409
$26,363
-$34,634
-$173
$4,964.71
Green infrastructure has a number of other benefits to the Town of Franklin in addition to
phosphorus reduction. Green infrastructure also reduces loading of other pollutants, such as
sediments, nitrogen, hydrocarbons, metals, and bacteria. The use of green infrastructure can
also mitigate the warming effect that stormwater runoff has as rainwater collects on hot paved
surfaces and is then quickly discharged to downstream water bodies.
Green infrastructure can also save the Town money, which can be used to support other
municipal needs. For example, two of the projects highlighted in the 2012 Memo (pavement
reduction and conversion to phosphorus-free fertilizer for municipal properties) had a net
negative project cost, saving the Town over $15,000. Reducing the annual runoff volume
through the use of green infrastructure also lessens the load on storm sewer systems and
downstream water resources, which reduces maintenance costs and streambank erosion
issues. Maintenance costs also tend to be lower with above-ground stormwater management
systems, such as bioretention facilities, due to easier access and the mostly landscape-related
activities.
In addition to the pollutant removal and fiscal benefits of green infrastructure, green
infrastructure can have other benefits that, while not always easily quantifiable, are important
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to the Town. For example, green infrastructure, which incorporates natural vegetation as a
primary means to mimic natural hydrology, often increases habitat and offers greater wildlife
biodiversity compared to traditional stormwater practices. Green infrastructure practices also
tend to provide green spaces for the public to enjoy. The creation and preservation of open
space is important to the Town of Franklin, and through its Master Plan, the Town has
committed "to assure that our preservation of open space and recreational land keeps pace
with the Town's buildout, protects our environmental resources and preserves our New
England character" (Town of Franklin, 1997). Lastly, green infrastructure has been linked to
higher property values (CNT, 2010). In general, property values tend to increase when they
abut landscaped, open areas (such as those used for green infrastructure) versus abutting
uninterrupted paved areas such as parking lots and streets. Further discussion of all of the
benefits described here is provided in Attachment 1. The next section will introduce how new
green infrastructure projects, programs and policies can further these benefits that Franklin is
already starting to experience.
m
Figure 1-4. Multiple Community Benefits of Green Infrastructure
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1.4 Implementing Green Infrastructure: Projects, Programs, and Policies
The implementation of green infrastructure, transitioning from "gray to green," can occur
through the implementation of projects, programs, and policies. Table 1-2 summarizes the
definition of projects, programs, and policies and provides an example of each. In general,
projects can be thought of as unique installations with a start and end date. For example,
the installation of a green roof on a school or a bioretention retrofit to a municipal parking lot
can be thought of as projects. A program can be thought of as an ongoing initiative that
often includes a group of projects, such as a public education campaign on the benefits of
green infrastructure or training program on how to install residential-scale green
infrastructure. A policy is usually a document developed by a government or business that
identifies a plan, often times for implementing a program. For example, Franklin recently
instituted a local government policy to switch from conventional fertilizer to phosphorus-free
fertilizer on all municipal properties. The following sections of this report will describe how
existing and proposed Town projects, programs, and policies will fit into the Town's Green
Infrastructure Strategy.
Table 1-2. Green Infrastructure Projects, Programs and Policies
Project
Program
Policy
Definition
Temporary undertaking with a defined start and end
point and specific objectives to create a unique
installation or service that, when attained, signify
completion.
A group of related projects managed in a coordinated
way to obtain benefits not available from managing
the projects individually. A program may also include
elements of on-going, operational work.
A plan or course of action, either set by a government
or business, intended to influence and determine
decisions, actions, and other matters.
Example
New bioretention retrofit project at
a municipal parking lot
Public "Build-your-own-rain-
garden" training program
Local government policy to switch
to phosphorus-free fertilizer on all
municipal properties.
1.5 Franklin's Green Infrastructure Goals and Objectives
The Town has identified several goals and objectives for the implementation of green
stormwater infrastructure. The goals and objectives are summarized in Table 1-3. These are
intended to help the Town identify what potential barriers may exist for practices, programs
and policies and how they may address them. They also provide guidance for implementing
new practices, programs, and policies that will help provide effective stormwater management
of the Town's MS4 and individual private properties.
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Table 1-3. Goals and Objectives for the Town of Franklin's Green Stormwater Infrastructure Implementation
Goal Description
Minimize directly-
connected impervious
area
Preserve the hydrologic
function of natural
features
Allow and encourage
m ulti-fun ction al
stormwater controls
Increase public
involvement, education,
and outreach
Address the Upper
Charles River TMDL
Provide cost effective
stormwater
management
Objective
Minimize
impervious area
associated with
streets
Minimize
building foot
print
Promote green
infrastructure in
landscaped
areas
Add public
signage
Reduce
phosphorus for
new and
redevelopment
projects
Integrate green
infrastructure
into other
development
projects
Minimize
impervious area
associated with
parking
Preserve topsoil
Promote green
infrastructure in
open areas
Increase green
infrastructure in
public areas
Reduce
phosphorus from
existing
development
Identify green
infrastructure
opportunities that
address multiple
community goals
Minimize
impervious area
associated with
driveways and
sidewalks
Preserve trees
Promote green
infrastructure on
roofs
Develop
public/private
partnerships
Provide
phosphorus
pollutant non-point
source control
Create guidance for
interdepartmental
and review board
coordination
Promote
permeable
pavements
Preserve
existing
topography
Promote green
infrastructure
in rights-of-way
Provide public
training
sessions/
workshops
Create maps
and databases
to support and
monitor data
Preserve open
space
Redirect
stormwater from
gray to green
infrastructure
Develop an
education program
for phosphorus
fertilizer ban
Develop an
incentives program
Preserve
wetlands
Encourage
green
infrastructure
approaches
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2.0 Projects
The Town of Franklin has been implementing green infrastructure practices into their projects
to help them meet their goals and objectives as described in Section 1. This section provides a
summary of the green infrastructure practices that are already in place as well as those that
may be available to the Town for future projects, including:
Bioretention/Green Streets
Infiltration
Rain Harvesting
Permeable Pavement
Constructed Wetlands
Green/Blue Roofs
Non-structural
Each subsection has a discussion of the practice, including short descriptions of the various
applications, a summary of existing projects, and a description of potential future project
applications.
2.1 Bioretention/Green Streets
Bioretention systems are shallow landscaped areas that are designed for small drainage areas.
These practices mimic the hydrologic processes of pre-developed land, including infiltration,
storage, filtration and pollutant uptake, primarily through the use of engineered soils and
native plantings. Underdrain systems can be installed to provide flow control for poorly-
draining soils.
Bioretention applications can take several different forms, such as bioretention cells, tree
filters, stormwater planters, rain gardens, and bioswales. Green Streets incorporate the various
types of bioretention as well as other tools, like stormwater bumpouts, to address stormwater
runoff from streets and sidewalks. Green Streets are implemented in rights-of-way and are
designed to maximize stormwater management while maintaining the primary functions for
pedestrians, bicyclists and vehicles.
Descriptions of these applications are provided in Table 2-1 below. The applications can be
applied in new development, redevelopment and retrofit projects and can be a stand-alone
practice or integrated with other multifunctional green infrastructure practices.
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Table 2-1. Descriptions of Bioretention/Green Street Practices
Application
Description
Example Photo
Bioretention
Cells
Shallow depressions that accept flows from small,
gently sloping drainage areas. Designed with a
planting soil mix and a variety of plants, selected
based on the site condition (e.g., shade,
underlying soil types, etc.). May or may not have
an underdrain system. These systems are
applicable in both urban and suburban locations.
Tree Filters
Compact, self-contained systems filled with a soil
mixture, vegetation and an underdrain system.
These systems are often seen in urban settings
along sidewalks to collect and filter runoff from
roadways and parking lots.
Stormwater
Planters or
Planter Boxes
Vertical walled containers, often constructed
within concrete, that include filter media and
vegetation. These systems are designed to treat
limited volumes of runoff, typically from rooftops
via downspouts or small areas of sidewalk.
Planters may have an open bottom that allows
infiltration or may be planter boxes, which have a
closed bottom that requires use of an
underdrain. Both practices are typically used in
high density urban areas.
Rain Gardens
Similar to bioretention cells, but generally
excavated into native soils with only modest soil
amendments, such as compost and/or sand and
no underdrain. These practices are well-suited
for installation in residential areas.
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Application
Description
Example Photo
Bioswales
Similar to bioretention cells, but are designed to
convey stormwater when maximum ponding
depth is exceeded. Bioswales are typically seen
in residential areas.
2.1.1 Existing Bioretention/Green Street Practices
The Town has completed a number of green infrastructure projects using bioretention
applications. Representative projects include:
Lockewood Drive
This project incorporated a retrofit of an existing dry "detention pond" that had modest
detention and limited treatment due to an at-grade outlet pipe. The modifications included a
plunge pool, sediment forebay and bioretention cell which overflows into an infiltration basin.
Wachusett Street
Retrofits and upgrades along this busy street were installed in two sub-watersheds: Parmenter
School and Fletcher Field. At Parmenter School, four bioretention areas were installed as pre-
treatment to underground infiltration chambers. At the Fletcher Field Lot, flow was directed to
a sediment forebay which discharged into a standalone bioretention cell.
Miller Street (at the intersection of Green Street)
Scheduled to be completed in 2013, this project will include removing excess pavement and
replacing it with grass and a rain garden. The rain garden will serve as pre-treatment to
underground infiltration chambers.
Greensfield Road
Greensfield Road was an existing cul-de-sac that had excess, unnecessary pavement once a spur
road was added. For this project, the Town Department of Public Works (DPW) removed the
pavement, replaced the impervious cover with grass, and installed a rain garden to manage
stormwater runoff from a portion of the road.
Downtown Franklin Roadway and Streetscape Improvement Project
This project incorporates improvements to the roadways, rights-of-way and adjacent areas in
downtown Franklin to revitalize the area. The Town is working with the Massachusetts
Department of Transportation (MassDOT) to complete the project. The Town's portion of this
project included tree filters and rain gardens at a public parking lot.
Results from a recently completed assessment of the benefits of these projects show that
annual total phosphorus reductions of greater than 20% up to 84% were able to be achieved
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using bioretention practices or a combination of bioretention and other green infrastructure
practices. Project cost evaluations indicated that the annual cost to reduce total phosphorus
ranged from $2,000 to $30,000 per Ib of phosphorus; the costs varied due to the variable
drainage areas and the variability of the practices that made up the projects. Overall, the
assessment concluded that bioretention systems were successful at addressing the Town's
phosphorus loading and were cost effective, particularly when compared to underground
stormwater management practices.
2.1.2 Proposed Bioretention/Green Street Practices
The Town can incorporate bioretention practices into both existing and proposed stormwater
management systems, particularly in public areas, such as parking lots and parks, and along
roadways, creating green streets. Green streets not only manage and treat runoff from the
adjacent roadways but offer added visual quality which can attract residents and local
businesses and provide for stormwater education opportunities. The Town should continue to
work with MassDOT as part of their Downtown Roadway and Streetscape Improvement Project
to incorporate bioretention practices into MassDOT's portion of the project. To increase public
involvement and encourage bioretention on private properties, the Town could provide rain
garden workshops, develop support materials, or even help fund private installations. Table 2-2
below provides guidance on design, benefits, limitations, operations and maintenance needs,
and potential costs for bioretention systems.
Table 2-2. Guidance for Implementation of Bioretention/Green Street Practices
Design
Should be used in conjunction with pretreatment practices to increase efficiency.
Should be sized for small drainage areas (generally less than 10 acres).
Can be used for practices when vertical separation from bedrock or ground water is
less than one foot (requires design provisions).
Native, hardy plants should be used to increase likelihood of survival.
Benefits
Helps maintain the natural water balance of a site.
Helps to recharge the groundwater and drinking water supply when practices are
unlined.
Creates a green space which is ideal for increased biodiversity and aesthetically
pleasing to the public.
Can easily be modified for stormwater retrofits for small existing drainage areas.
Excellent opportunities for educational outreach.
Limitations
Bioretention cells and rain gardens are not ideal for steep slopes, but can be
implemented with design provisions.
Long-term landscape-oriented maintenance is required to ensure adequate
performance and aesthetic value.
Requires measures to divert large flows, whether by structural overflows or being
installed off line from a treatment train.
Operation
and
Maintenance
Regular landscape activities such as mulching and weeding.
Sediment removal as needed.
Specific attention to health of plantings and diligence in replacing dead, diseased, and
invasive species.
Costs
Bioretention cells typically run $20-$30 per square foot (HW, 2012).
Rain gardens are almost half of the above cost.
Tree boxes and planters are typically more expensive due to street side installation.
Bioswales are similar in cost to bioretention cells.
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2.2 Infiltration Practices
Infiltration practices are designed to manage stormwater though infiltration of runoff into
the soil. These practices increase groundwater recharge and have excellent pollutant removal
capability. Infiltration practices are only suited for sites with adequate soils and separation
distance to groundwater. They can be above or below ground, and through their capture and
storage of runoff, help attenuate large flows. Infiltration practices must have pretreatment
by a prior BMP.
Table 2-3 below has brief descriptions of various infiltration practices applicable to Franklin.
These practices can be used during new or redevelopment, and are appropriate for suburban
and urban areas. Franklin can initiate public interest by highlighting projects it has already
completed and should continue to construct infiltration practices as a part of both retrofit
and new development projects.
Table 2-3. Descriptions of Infiltration Practices
Application
Infiltration Basins
Infiltration
Trenches
Description
Above ground excavated areas. They are
typically capable of temporarily storing
larger amounts of runoff, which is
exfiltrated through the bottom of the
basin into the underlying soils.
Infiltration basins do not generally
include significant landscaping but can
certainly be designed with plantings as a
project amenity.
Trenches are typically narrow, elongated
excavations filled with stone or
prefabricated materials to provide void
space. The voids between the stone
allow for storage and infiltration into the
soil below. The linear shape allows
trenches to be used effectively along
buildings, parking lots, or roadways.
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Application
Description
Example Photo
Underground
Chambers
A variety of shapes and sizes of structural
products can be used. The structures are
buried underground and surrounded by
stone to provide storage and support. An
overflow is typically provided for large
storm events. They can be designed to
withstand the heavy loading of parking
lots and roadways, which can be ideal for
sites with space limitations.
Dry Wells
Small excavated pits, filled with stone,
with or without structural components.
Downspouts are attached to dry wells to
manage roof drainage; an overflow pipe
is typically provided for large storm
events. Dry wells are ideal for smaller
rooftop areas.
2.2.1 Existing Infiltration Practices
Infiltration practice applications have been used by the Town in retrofits of past projects. Two
of these projects are described below.
Panther Road
A diversion manhole, new sediment forebay, and new infiltration basin were installed to
provide stormwater management for a police station parking lot as well as the existing storm
sewer system on Highwood Drive, which had runoff from a condominium development with no
prior stormwater management. The system relieved existing flood issues and now provides
water quality treatment and groundwater recharge to a stream system that feeds Mine Brook,
a tributary of the Charles River.
Wyllie Road
Wyllie Road is part of the larger Miller Street- Wyllie Road grant project. An existing
stormwater sewer system was retrofitted with underground infiltration chambers in
combination with other green infrastructure practices to provide stormwater management
prior to discharge.
The recent assessment of Franklin green infrastructure projects shows decreased phosphorus
loading and runoff volume of greater than 80% and 75%, respectively. These reductions are
some of the highest found from the assessment. Costs of annual phosphorus removal were
approximately $5,000 and $26,000 per pound; the large difference in costs can be attributed to
the increased costs of underground chambers versus above ground basins.
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2.2.2 Proposed Infiltration Practices
The Town should consider the benefits of infiltration practices when working on new and
redevelopment projects. Much of Franklin has well draining soils (approximately 50% of the
soils are classified as being hydrologic soil group A or B), so infiltration is an appropriate
practice for stormwater management. Also, infiltration practices help to meet Franklin's zoning
bylaws which require groundwater recharge for all projects within the Water Resource District,
unless it is infeasible due to contaminants or soil restrictions. Infiltration practices also have
the highest phosphorus removal capability, especially when coupled with bioretention cells as
pretreatment (HW, 2012). Both aboveground and underground applications can be used in
Franklin, depending on the project location and available land area. While above ground
practices cost much less, underground chambers are effective where site limitations exist, such
as under parking lots and roadways. Further guidance for designing and implementing
infiltration practices is provided in Table 2-4.
Table 2-4. Guidance for Implementation of Infiltration Practices
Design
Need to be placed in adequate soils (well draining, sandy soils are
preferred).
Can be sized for any storm event or drainage area.
Must have vertical separation from bedrock and groundwater of at
least two feet.
Must be used with pre-treatment practices (dry wells can be used
without pre-treatment if accepting roof runoff only).
Benefits
Helps to recharge groundwater and drinking water supply.
Temporary storage and attenuation help reduce peak discharge rates
and local flooding issues.
Infiltration and filtering through soil media provide high pollutant and
nutrient removal.
Reduces the need for other stormwater management practices.
Limitations
Regular maintenance is essential to prevent clogging.
Requires highly permeable soils and adequate distance to
groundwater to infiltrate stored water
Some potential for groundwater contamination if not designed or
sited properly.
Operation and Maintenance
Regular sediment removal.
Semi-annual inspections for erosion and scouring.
Direct access in the form of observation wells are needed for
underground systems.
Costs
Costs can vary widely with infiltration practices based on design and
site constraints.
In general, infiltration trenches are usually in the range of $20-30/sf,
and above ground structures cost about half of those below ground
(HW, 2012).
2.3 Rain Harvesting
Rain harvesting stores stormwater runoff in some kind of holding tank for future use. Nearly all
rain water harvesting involves collection and storage of rooftop runoff, but other applications
have been done. These practices can range from simple (e.g., installation of a rain barrel) to
complex (e.g., installation of an underground cistern with flow-controlling systems and pumps),
as described in Table 2-5. Installation of flow-control valves can help to reduce peak flows and
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runoff volume to downstream drainage areas. Harvesting can also reduce the need for
groundwater pumping. Water can be used for irrigation (e.g., for gardens/ landscaping on
private properties, golf courses, parks, etc.), toilet flushing, construction activities as well as a
variety of other activities. Rain harvesting is an easy first step for making the switch from gray
to green and is an adequate retrofit option for almost any building.
Table 2-5. Descri
Jtions of Rain Harvesting Practices
Application
Description
Rain Barrels
Plastic barrels (typically under 100 gallons)
used to store roof runoff. They are excellent
stormwater management additions to
residential or small lots.
Example Photo
Cisterns
These systems capture runoff from larger
buildings or multiple buildings (such as
housing complexes) or occasionally from
paved surfaces (like patios, driveways,
sidewalks, etc.). Cisterns can be placed
above or below ground. Above ground
cisterns generally store from 1,000 to 5,000
gallons. Below ground tanks typically range
in size from 5,000 to 20,000 gallons and use
pumps to distribute water. Below ground
tanks are more expensive due to excavation
and higher strength materials (reinforced
plastic or concrete). Cisterns are appropriate
for medium to high density residential and
industrial/commercial areas.
2.3.1 Existing Rain Harvesting Practices
During the spring of 2009 and 2010 Franklin offered rain barrels to Town residents at a
discounted price. This is an excellent form of outreach to help the public become aware of
stormwater issues and management. This also provides small scale peak flow reductions, which
can contribute to an overall decreased peak flow discharge.
2.3.2 Proposed Rain Harvesting Practices
Rain harvesting systems are ideal for both residential and commercial areas; they are simple
and require minimal space and design, as detailed in Table 2-6. Most buildings with external
downspouts can be retrofitted to use one of the above practices. In addition, recharge and
storage in these systems can easily be managed through the use of an automated system of
valves and pumps that are triggered by weather forecasts to transfer or release stored water.
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Franklin should continue to offer rain barrels to homeowners to promote their commitment to
green infrastructure. The Town could promote rain harvesting practices by installing rain
barrels and/or cisterns at public buildings, such as at Town Hall, the library or schools where the
projects would be highly visible. Rain harvesting projects are particularly beneficial for
buildings adjacent to grounds requiring irrigation. For example, large underground cisterns at a
school can provide the majority of watering needs for athletic fields. Water can also be reused
for toilet flushing inside schools or other buildings, assuming plumbing and any other relevant
codes are followed.
Table 2-6. Guidance for Implementation of Rain Harvesting Practices
Design
Roof top area and rainfall depth to be captured are the two main factors in sizing.
A minimum setback of ten feet from buildings is required.
Leaf litter and other debris will need to be blocked with a screening device.
Benefits
Require little space and are therefore easily employed in urban areas.
Can reduce potable water supply demand for irrigation applications.
Reduces runoff to stormwater management systems.
Limitations
Must be sealed to prevent mosquito breeding.
No direct pollutant or nutrient removal.
Require overflow mechanism for larger storm events.
Can only hold some of the total volume if not emptied between storms (flow
control technologies can optimize storage).
Use for flushing of toilets requires special plumbing requirement to meet
plumbing codes.
Operation and
Maintenance
Regular inspection of gutters, downspouts, and screens for clogging.
Planning ahead for water use so the unit can store the next storm.
During the winter months drains should be left open to prevent freeze-thaw
damage.
Costs
Costs are $2-3 per gallon for rain barrels and $1-2 per gallon for larger tanks (HW,
2012).
Below ground cistern units generally cost more than above ground ones because
of the additional cost of excavation.
2.4 Permeable Pavement
Permeable pavements help provide better stormwater management without sacrificing the
usefulness provided by hardscapes. These systems consist of a porous surface with underlying
layers of sand and/or stone. Alternative pavements can be built on fast infiltrating soils to
provide groundwater recharge and water quality benefits, but can also be installed in slower
infiltrating soils with the use of an underdrain system. They are recommended on pedestrian
and low traffic sites to extend their lifetime and decrease risk of failure. The four types of
permeable surfaces appropriate for use in Franklin are described below in Table 2-7.
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Table 2-7. Descriptions of Permeable Pavement Practices
Application
Description
Example Photo
Permeable Pavers
Pavers are impervious blocks that are
installed with spaces between them.
These spaces are filled with sand or
gravel to allow drainage between the
blocks and into the soil. Pavers are
typically used in patio and walkway
settings.
Porous Asphalt
Porous pavement is similar to
traditional blacktop, but has less fine
aggregate to increase void space.
These spaces allow stormwater to
percolate through the asphalt to the
underlying subbase. Porous asphalt is
used in place of traditional asphalt, on
parking lots and driveways.
Pervious Concrete
Pervious concrete looks similar to
traditional concrete pavement, but
has less fine aggregate to increase
void spaces and to allow rain to
infiltrate through the cover to the sub
base. Pervious concrete is a good
choice for sidewalks.
Pervious Concrete
Slabs
These function the same as porous
concrete but are manufactured in a
controlled environment, which allows
for greater quality control. Because
they are small and uniform, slabs can
be removed for cleaning or replaced
easily without disturbing the rest of
the cover. Slabs are appropriate for
sidewalks or other smaller
applications.
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2.4.1 Existing Permeable Pavement Practices
There are currently no known existing permeable pavement practices in Franklin.
2.4.2 Proposed Permeable Pavement Practices
The Town should consider the use of permeable pavement practices in place of traditional
pavement during the planning stages of future public projects. The Town should also consider
pervious covers when repaying and resetting public parking lots, sidewalks, or bike paths.
Sidewalks and pedestrian ways are ideal for these practices because pervious covers with less
vehicular traffic are easier to maintain. Although the initial cost of pervious walkways may be
greater than traditional sidewalk construction (depending on other requirements), the cost
over the life of pervious walkways are generally less. Cost savings are a result of reduced
maintenance (e.g., less sand would be required during winter months) and reduced need for
additional stormwater management infrastructure. Permeable pavements are applicable to all
future Town projects involving sidewalks and courtyard type areas. They are also relevant to
low-volume roads, parking lots, and driveways. In general, the Town should not consider these
practices for higher traffic roads.
Table 2-8. Guidance for Implementation of Permeable Pavement Practices
Design
Poorly drained soils need an underdrain system.
Depth of sub base is directly related to amount of available storage.
Must have vertical separation from bedrock and ground water of at least
two feet.
Should only be used in low traffic or pedestrian areas.
Benefits
Promotes filtration and groundwater recharge.
Reduces the need for salt and sand application during the winter months.
Reduces need for curbing and "gray" stormwater infrastructure.
Limitations
Regular maintenance (such as street sweeping) is essential to prevent
clogging.
Have strict site limitations for groundwater and soil needs to promote
infiltration and prevent groundwater contamination.
Not suitable for land uses with potential higher pollutant loads.
Operation and
Maintenance
Regular cleaning with vacuum assisted street sweeper.
Annual inspection to check for deterioration.
Requires reduced or no sand usage during winter months to prevent
clogging.
Costs
Costs can vary widely with size of area.
Permeable asphalts can range from as low as $3-5 per square foot
(depending on size of project and subbase requirements) (HW, 2012).
Porous concrete and pavers can range from $9-15 per square foot (HW,
2012).
2.5 Constructed Wetlands
Constructed stormwater wetlands are engineered systems designed to mimic natural wetlands.
They require larger drainage areas, at least ten acres per Massachusetts Stormwater
Management Standards (MASWMS), to ensure the system stays sufficiently wet. Often, they
are sited in soils with slow or no infiltration to create a permanent pool. Sediment forebays
are required on all types of stormwater wetlands.
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Pollutant, sediment, and nutrient removal are highly effective in these systems due to the
wetland plantings uptake and retention/settling from the permanent pool. The MASWMS lists
the removal efficiencies of constructed wetland systems as: 80% of total suspended solids
(TSS), 20-55% of total nitrogen (TN), 40-60% of total phosphorus (TP), and up to 75% of
bacteria. These are some of the highest of all the green infrastructure practices. In Table 2-9,
brief descriptions of the five basic types of constructed wetlands acknowledged by MASWMS
are provided.
Table 2-9. Descriptions of Constructed Wetland Practices
Application
Description
Example Photo
Shallow Marsh
Systems
These manage stormwater through
shallow pools, shallow marshes, and
high marshes. They may require a larger
drainage area than other constructed
wetlands because they lack deep pools.
Basin/Wetland
These practices contain all the
components of a shallow marsh system
and in addition have a wet basin and
plunge pool.
Extended Detention
Wetland
A smaller footprint than other
constructed wetland systems can be
achieved because of the vertical storage.
The deeper ponding depth resulting
from temporary ponding during storm
events require special attention to plant
selection.
Pocket Wetland
Adequate for drainage areas of one to
ten acres, these smaller practices should
be excavated into the groundwater table
to ensure they stay wet.
, Kni 'a
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Application
Description
Example Photo
Gravel Wetland
Gravel wetlands use sub surface,
horizontal flow to manage runoff. They
consist of a gravel subbase with an
option to add organic soil to
accommodate plantings.
2.5.1 Existing Constructed Wetland Practices
Franklin currently has no existing constructed wetlands.
2.5.2 Proposed Constructed Wetland Practices
Constructed wetlands can be used to manage drainage from large public areas, such as schools.
An example of this type of application is a recently completed constructed gravel wetland in
Harvard, MA that was designed to manage drainage of athletic fields at Bromfield High/Middle
School. The Town may also consider the suggestions from the recent Spruce Pond Brook
Subwatershed plan, which identified an area behind Fletcher Field as ideal for a gravel wetland
system.
Franklin should consider constructed wetlands in locations where other practices are
inadequate due to groundwater or lack-of-elevation constraints. In addition, these systems can
have high pollutant removal efficiencies and can greatly help reduce phosphorus loading to the
Charles River. Table 2-10 provides guidance information for the implementation of constructed
wetlands within the Town.
Table 2-10. Guidance for Implementation of Constructed Wetlands
Design
Constructed wetlands need sufficiently large drainage area and/or
groundwater influence to remain wet.
Must have a sediment forebay or other BMP as pretreatment.
Proportions of "depth zones" must be in accordance with MASWMS.
Medium to fine texture soils are best for establishing vegetation,
retaining surface water, facilitating groundwater discharge and
capturing pollutants.
Water budget must demonstrate a continuous supply of water is
available to sustain the constructed wetland.
Benefits
Reduces peak discharge rates and runoff volume.
Effectively reduce sediment and pollutant loads.
Offers marsh like habitat, which increases biodiversity in areas lacking
such ecosystems.
Enhances the aesthetics of the site.
Limitations
Potentially require larger footprint than other BMPS.
Does not provide groundwater recharge.
Require native plantings (e.g. Carex, Scirpus, Juncus, and Lemna).
Can be difficult to maintain during extended dry periods.
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Operation and
Maintenance
Constructed wetlands require small-scale maintenance at regular
intervals.
Should be inspected during growing and non-growing seasons.
When inspecting look for: invasive species, distribution of wetland
plants, standing water without plantings, and stability of original
"depth zones."
Removal of built up sediment from the forebay.
Costs
Constructed wetlands costs vary widely depending on drainage area
treated and site constraints; median cost for new construction is
approximately $3,000 to $10,000 per impervious acre treated
(Schueler, etal., 2007).
2.6 Green/Blue Roof Practices
Green and blue rooftop systems are alternatives to traditional roof construction in which
precipitation is managed beyond a gutter system. They are typically better suited for new
construction projects versus redevelopment and retrofits, but can be used in both. One
important design consideration with these systems is the additional structural loading due to
the increased load, which will require consultation with a structural engineer prior to
installation. Both green and blue roof systems are designed to provide detention and can
potentially provide some volume reduction through evaporation. Table 2-11 below discusses
the differences between these two practices.
Table 2-11. Descriptions of Green/Blue Roof Practices
Application
Description
Example Photo
Green Roof
Soil media, an underdrain system, and
vegetation are used to store and slow
rainfall before it becomes runoff. Voids
in the sub base provide attenuation and
storage of water while plantings provide
uptake, treatment, and runoff reduction
through evapotranspiration. Extensive
green roofs have a shallow soil media
for small, ground cover type, plants and
are not intended for public access.
Intensive green roofs have a deeper soil
structure, capable of growing larger
plants; these practices are designed for
public access. Green roofs are
appropriate for large public buildings,
such as schools, offices, and libraries.
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Application
Description
Example Photo
Blue Roof
Blue roofs provide storage and
detention through chambers, trays,
check dams, or outlet restrictions.
Evaporation can occur in small amounts
and provide minimal runoff reduction.
Typically the main goal of these systems
is to reduce peak flows through
attenuation. Blue roof options are
adequate for retrofits of existing public
buildings.
2.6.1 Existing Green/Blue Roof Practices
Franklin currently has no existing green or blue roofs.
2.6.2 Proposed Green/Blue Roof Practices
Green and blue roof systems are best suited for new construction projects, when all options
can be discussed in advance to ensure the structural design of the building incorporates the
above average loading from the roof system. Green roofs can offer energy savings through the
natural heating and cooling properties of soils and evapotranspiration. Intensive green roofs
can also offer unique opportunities for education, green public space, and possibly local
gardening projects. Franklin should consider these options when planning a new public
building such as Town offices or schools.
The Town should also investigate simple retrofits of existing roofs, both on Town-owned and
private property (institutional, commercial and residential). Several retrofits have already been
completed in the New England area: a green roof at Underground Art Gallery in Brewster; a
food roof at Ledge Kitchen and Drinks Restaurant in Dorchester; and green roofs at private
residences in Newton, Winchester, and Boston. A case study of a green roof retrofit at Whipple
Riverview Place in Ipswich conducted after its completion in 2006 found that the green roof
was particularly effective at delaying and retaining stormwater runoff.
Table 2-12. Guidance for Implementation of Green/Blue Roof Practices
Design
Need a structural engineer to verify loading capacities for both types.
Need high quality impermeable barriers to prevent leaking for both
types.
Need to take into consideration public access when designing green
roofs.
Benefits
Both systems provide detention and peak flow rate reduction.
Both can provide some volume reduction.
Green roofs provide energy savings through natural heating and cooling
properties of ground and plant transpiration.
Green roofs have longer life spans than traditional roofs.
Green roofs can provide wildlife habitat and green space.
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Limitations
Operation and
Maintenance
Costs
Must adhere to local building codes and load restrictions.
Pollutant removal capabilities have not been adequately studied.
Does not recharge groundwater.
Need periodic landscape related maintenance for green roofs.
Need periodic inspection to ensure water tightness and prevent clogging
for both types.
Typically cost between $144-$420 per cubic foot treated (Schueler, 2007).
2.7 Non-Structural Practices
Green infrastructure practices are not limited to constructed structural methods. Non-
structural practices include: open space preservation, encouraging site fingerprinting,
encouraging natural landscaping, reducing impervious cover, and providing source control, such
as enhanced street sweeping. This variety of options promotes maintaining existing hydrologic
patterns and dissuades adding extraneous impervious cover. These practices also help
prevent runoff and pollution, which helps reduce the burden on stormwater management
systems. Table 2-13 lists five different non-structural practices appropriate to the Town.
Table 2-13. Descriptions of Non-Structural Practices
Application
Description
Example Photo
Open Space
Preservation
Conservation practices such as
protecting sensitive areas like wetlands
helps maintain existing hydrologic
patterns. Open space can also be
recreation areas, such as hiking trails or
athletic fields.
Encourage Site
Fingerprinting
Site fingerprinting is a land
development strategy that
incorporates an analysis prior to site
development to identify key natural
features to be protected during
construction. This includes: mapping
existing trees, drainage divides, and
highly permeable soils.
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Application
Description
Example Photo
Encourage Natural
Landscaping
Native vegetation is well adapted to its
region. It tends to require less
irrigation and fertilizer while
performing better than exotic species.
Natural landscaping can be done in
place of most conventional landscaping
with less impact on the environment.
Reduce Impervious
Cover
Today's standards and requirements
for paved surfaces may be less strict
than those from the past when many
roads and sidewalks were built. When
repaving roads or resetting sidewalks,
opportunities exist for reducing the
size of the original impervious cover
and replacing with a green cover.
Provide Source
Control
Source control can include: using less
fertilizer, using less salt during winter
months, and providing adequate street
sweeping.
2.7.1 Existing Non-Structural Practices
Several non-structural practices have been implemented in the Town. Two of these projects
are described below.
Greensfield Road
As described in Section 2.1.1, the DPW recently replaced excess impervious area in a former
cul-de-sac with pervious lawn cover and a small rain garden. This project provided a net cost
savings because the Town no longer has to maintain the excess pavement.
Town Properties
In 2008, the Town of Franklin began using zero phosphorus fertilizer on all Town-owned
property, which includes active use turf (e.g., sports fields) and passive use turf (e.g., lawn
around buildings and in parks). By switching to zero phosphorus fertilizer, Franklin
implemented source control and reduced the phosphorus loading to nearby storm sewers and
surface waters by over 30 pounds per year.
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2.7.2 Proposed Non-Structural Practices
For future paving projects, the Town should consider reducing impervious cover, such as
reducing road widths or using pervious pavements in public parking lots. Reducing salt and
sand use on roadways during winter months is an effective source control that not only helps to
improve water quality and provide cost savings, but also limits negative effects on other green
infrastructure practices.
For future public projects (buildings, schools, parks), the Town should strive to maintain natural
hydrologic patterns and vegetation and conserve trees and open spaces to the extent possible.
In addition, natural landscaping should be considered instead of conventional landscaping (i.e.,
turf grass). Not only will this reduce irrigation and fertilizer needs, but it will also provide an
example to the community.
Table 2-14. Guidance for Implementation of Non-Structural Practices
Design
Street sweeping for source control should be performed by a vacuum-assisted
sweeper and done at least twice per year for enhanced removal efficiency.
Benefits
Maintains pre-development hydrologic and drainage patterns.
Open space provides aesthetic appeal, recreational opportunity, and wildlife
habitat.
Increased natural vegetation reduces irrigation and fertilizer needs.
Increased natural vegetation provide uptake of nutrients, pollutants, and water.
Replacing impervious cover reduces life time costs of repaving, and reduces volume
of storm water runoff.
Limitations
Street sweeping requires efficient sweeper and regular sweeping to be effective.
Site fingerprinting requires more attention and time during initial site design.
Reduction in use of salt and sand can pose safety hazards.
Operation and
Maintenance
Natural landscaping requires general landscape related tasks, but less often than
conventional methods.
Costs
Zero phosphorus fertilizer can be less expensive than conventional.
Reducing salt and sand usage is a cost savings.
Natural plantings can incur lifetime savings by reducing need for fertilizer, watering,
and other maintenance.
Cost of conservation land depends on many factors.
Site fingerprinting requires finer attention to detail in early stages of design and
thus can be more expensive than traditional design.
Vacuum-assisted sweepers are on the order of $200,000, generally one and a half
to two times the price of a conventional mechanical sweeper (HW, 2012).
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3.0 Programs
The Town of Franklin has several existing programs under the Town's departments that utilize
green infrastructure practices for stormwater management. This section provides a summary
of those green infrastructure programs as well as suggestions for potential improvements to
strengthen those programs. In addition, recommendations for new programs are provided to
help the Town further integrate the green infrastructure practices described in Section 2 as
well as meet the Town's goals and objectives described in Section 1. This section is sub-
divided based on the Town's major program activities: Education, Community Planning and
Development, and Operations and Maintenance.
3.1 Education
3.1.1 Existing Education Programs
The Department of Public Works currently has a stormwater education program as part of the
NPDES MS4 permit. This stormwater education program includes: information provided on the
Town's website and the newspaper, water resource information and protection signs,
classroom stormwater education, and educational materials concerning waste disposal and
water conservation. Potential improvements to the existing stormwater education program to
promote green infrastructure could include:
Updating the current stormwater education program to include information specific to
green infrastructure and its benefits for phosphorus reduction and options for pollution
prevention.
Expanding stormwater education in public areas to increase public outreach. For
example, adding signs in parks to address potential pollutants, such as pet waste, or
providing additional stormwater and green infrastructure educational materials in
mailings or at the local library.
3.1.2 Proposed Education Programs
Implementing additional education programs can help the Town to gain and broaden
community knowledge and support, which will help ensure success of green infrastructure
programs in the long-term. The potential new education programs to support green
infrastructure are described in Table 3-1.
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Table 3-1. Descriptions of Proposed New Education Programs
Program Description
Benefits
Limitations
Use existing green infrastructure
projects as demonstration projects
(e.g., Lockewood Drive, Panther
Way, Wachusett Street, etc.)
Increases public knowledge
about the benefits of green
infrastructure
Helps gain community
support for future green
infrastructure projects
Current projects may be in
areas where public access,
and therefore public
education, may be limited
Helps to gain community
support for green
infrastructure
Increases public knowledge
about green infrastructure
Creates shared marketing
opportunities across
stakeholders
Create a community partnership
with local stakeholders, including
private partners (e.g., local
developers) and academic partners
(e.g., Dean College).
Requires interest from
local organizations
Hold periodic information/training
sessions on green infrastructure
applications. Training sessions can
be held internally for maintenance
crews, engineers, and local
government officials and externally
for potential developers and
members of the general public.
Helps all parties involved in
new and redevelopment
projects understand the
green infrastructure
concepts, how they may
apply and how they need to
be maintained
Helps the interested public to
understand the technical
details, ask questions and
provide feedback
May require additional
staff time and funds
Create an education program to
provide information on the
upcoming statewide ban on
phosphorus-containing fertilizers
that expands to non-municipal
properties starting January 1, 2014.
Helps prepare local residents
and businesses to prepare in
advance of the statewide ban
May require additional
staff time and funds
3.2 Community Planning and Development
3.2.1 Existing Community Planning and Development Programs
There are three departments that address local bylaws, regulations, and guidelines for new
and redevelopment projects: the Conservation Department, the Planning and Community
Development Department, and the Building/lnspections/Zoning Department. These
departments have Boards that review projects to determine their compliance with the local
code. Currently, the Town of Franklin's Best Development Practices (BDP) Guidebook is the
primary guidance used to encourage the implementation of green infrastructure.
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Potential improvements to promote green infrastructure could include:
Modifying Town codes to support the implementation of green infrastructure. A recent
review of the local codes was conducted (HW, 2013b), which can be referenced to assist
the Town with revisions to policies, removal of potential barriers, and to encourage
green infrastructure practices. Language should be consistent between all policies to
avoid conflicting design requirements and ensure green infrastructure is implemented
to the maximum extent possible.
Modifying wetlands regulations to encourage green infrastructure and require
applicants to design stormwater management based on the BDP guide, where
applicable. Consider adding requirements for applicants to document phosphorus
loading and directly connected impervious area (DCIA) reductions.
Updating the BDP Guidebook to improve consistency with Town codes and include
green infrastructure practices and methods, such as infiltration practices. BDP goals
should be expanded to:
o Include treatment practices with a documented capability to reduce phosphorus
loading;
o Provide methods and approach for documenting reductions in DCIA; and
o Promote a minimum requirement for redevelopment projects in place of a
maximum extent possible requirement.
Updating the Design Review Commission Design Guidelines to reference green
infrastructure and its goals, specifically as they relate to the site layout, parking, site
design and landscaping, paving materials and rooftop design (e.g., encourage green
roofs for large retail/commercial projects).
Updating the Open Space and Recreation Plan to specifically describe green
infrastructure and its benefits, including references to the impacts of phosphorus and
the benefits of phosphorus reduction to support the restoration goals of the Upper
Charles River TMDL.
Promoting following or obtaining Leadership in Energy and Environment Design (LEED)
certification or other green infrastructure-related certifications (e.g., the Sustainable
Sites Initiative). The criteria for these programs can be used to supplement the existing
guidance in the BDP Guidebook.
Educating review boards, Town engineers, and potential developers on any revisions to
codes, policies, or guidance documents, particularly those related to green
infrastructure, to help ensure proper implementation.
3.2.2 Proposed Community Development Programs
New community development programs can help the Town provide pathways for the Town,
developers, residents, and businesses to successfully implement green infrastructure practices
while also providing incentives to encourage additional green infrastructure practices. The
potential new community development programs to support green infrastructure are described
in Table 3-2.
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Table 3-2. Descriptions of Proposed New Community Development Programs
Program Description
Benefits
Limitations
Create a checklist for the review
boards that include steps for
coordinating with other
departments and review boards to
ensure that project site plans and
design strategies use green
infrastructure to the maximum
extent.
Provides a consistent
pathway for
interdepartmental
communication during the
review process
Ensures developers are
receiving consistent
feedback during reviews
May result in longer internal
design review periods
Develop an incentives program for
developers that utilize green
infrastructure. Incentives programs
can vary, but generally involve a cost
savings or potential for increased
revenue. Examples of incentives
include an expedited permitting
process, waiving of permitting fees,
or density bonuses.
Encourages green
infrastructure on private
property
May attract more
developers and businesses,
providing economic
benefits
Incentive programs can be
complex and costly to
initiate and administer
Incentives need to be
reasonable for the Town
(i.e., appropriate for the
Town's budget) but
significant enough for
developers to be willing to
participate
3.3 Operations and Maintenance
The Department of Public Works and the Facilities Department are the two main
departments that are involved with operations and maintenance (O&M) of Town's
infrastructure. The Department of Public Works has six different divisions that manage the
daily O&M programs and activities:
Engineering Division
Highway Division
Water and Sewer Division
Recycling and Solid Waste Division
Parks and Grounds Division
Engineering Division
3.3.1 Existing Engineering Division Programs
The Engineering Division includes engineering, map and CIS services for the Town. Current
programs under this division that help to promote green infrastructure include:
Designing internal construction projects that include green infrastructure
Providing technical review of both internal and external designs
Mapping of Town resources, including water resources (including wellhead protection
areas), streets, parcels, etc.
Mapping of O&M routes and schedules (e.g., street sweeping, snow removal, etc.)
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Potential improvements to promote green infrastructure could include:
Providing data on the Town's website (Public Map Viewer) for mapping of green
infrastructure site suitability, including: soil groups, slopes, watershed areas, depth to
water table, and depth to bedrock.
3.3.2 Proposed Engineering Division Programs
The Engineering Division can use its existing services in designing and mapping to develop new
programs that promote green infrastructure in internal projects as well as track the progress of
green infrastructure project implementation throughout the Town. The potential new
programs are described in Table 3-3.
Table 3-3. Descriptions of Proposed New O&M Programs under the Engineering Division
Program Description
Benefits
Limitations
Create a checklist for projects
designed internally by the Town
engineers to ensure that green
infrastructure is used to the
maximum extent possible for site
plans and design strategies for new
and retrofitted stormwater
management projects.
Helps promote green
infrastructure (particularly,
phosphorus reduction and
use of permeable
pavements) for internal
projects that are not
currently under the
jurisdiction of Town codes
and regulations
Longer internal design
review periods initially
Difficult to use for
emergency projects
Establish a DCIA tracking system
using GIS and/or a database to
support the annual reporting to be
in accordance with the draft MS4
permit.
Helps to meet a regulatory
requirement
Can make annual reporting
more efficient as a result of
continuous updating
May require additional staff
time and funds
May require additional
coordination between
applicants, engineers, and
outside agencies
Establish a maintenance tracking
system for new green infrastructure
using GIS or a database.
Can be incorporated into
existing maintenance maps
to increase efficiency
Easier to develop
maintenance schedules and
work orders
May require additional staff
time and funds
May require additional
coordination between
applicants, engineers, and
outside agencies
Develop and maintain a green
infrastructure database and GIS data
for tracking of green infrastructure
projects. Examples of green
infrastructure data to be collected
include project locations, green
infrastructure design elements,
costs, performance (e.g.,
phosphorus reduction), etc.
Helps to track on-going and
future projects
Helps to identify areas of
improvement for future
green infrastructure
designs
Helps support the draft
MS4 permit requirement
for GIS mapping of all
drainage infrastructure
May require additional staff
time to collect green
infrastructure data, funds,
and coordination with
applicants and engineers
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Highway Division
3.3.3 Existing Highway Division Programs
The Highway Division is responsible for the roadways, sidewalks and stormwater drainage
systems in the Town. The current programs under this division that contribute to the
implementation of green infrastructure include:
Snow and ice removal,
Street sweeping, and
Catch basin cleaning.
These nonstructural practices help to limit potential pollutants from entering the stormwater
system and improve water quality.
Potential improvements to promote green infrastructure could include:
Reducing the amount of salt and sand used on lower priority streets. Calibration devices
help vary the amount of salt applied based on site-specific characteristics, such as road
width and design, traffic concentration, and proximity to surface waters.
Identifying proper sites for snow disposal and develop site maintenance procedures.
Ensuring street sweeping occurs during the period immediately following winter
snowmelt, when there is a large amount of sand and other accumulated sediment and
debris on the roads.
Sweeping the entire width of the roadway.
Sweeping slower to achieve maximum efficiency.
3.3.4 Proposed Highway Division Programs
New programs under the Highway Division can help to further promote the implementation of
green infrastructure practices in roadways and rights-of-way as well as provide greater
efficiency between departments when new green infrastructure projects are being planned.
The suggested new programs under the Highway Division to support green infrastructure are
described in Table 3-4.
Table 3-4. Descriptions of Proposed New O&M Programs under the Highway Division
Program Description
Develop an enhanced street
sweeping program as defined in
guidance in the draft Residual
Designation Authority (RDA)
General Permit to receive non-
structural phosphorus reduction
credit. Additional phosphorus
reduction credit can be obtained
by increasing frequency of
sweeping from monthly to weekly
and/or using a regenerative
air/vacuum assisted sweeper in
place of a mechanical sweeper.
Benefits
Decreases the phosphorus
load reduction needed
through structural methods
to meet the goals
established under the Upper
Charles River TMDL
Limitations
Requires additional staff time
and funding, including
purchasing new street
sweepers
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Program Description
Benefits
Limitations
Implement coordination meetings
and/or inter-departmental
memoranda of agreement (MOA)
between the highway, water and
sewer, and engineering divisions
to identify opportunities for green
infrastructure (e.g., including
infiltration and/or impervious area
reduction when roads and/or
sidewalks are being installed or
redeveloped).
Greater efficiency
addressing Town needs
Potentially reduced project
costs
May require additional
coordination and staff time
Develop a Green Streets program
to integrate green infrastructure
practices into existing stormwater
management in rights-of-way.
Green Streets can be integrated
into broader transportation
improvements (e.g., during
roadway maintenance and
infrastructure improvements
(water, sewer, utilities, etc.).
Improves water quality
Increases safety for
pedestrians and bicyclists
Improves street aesthetics
Potentially reduced future
paving costs
May increase the lifespan of
the existing drainage
infrastructure
May require additional
coordination with other
departments
Water and Sewer Division
3.3.5 Existing Water and Sewer Division Programs
The Water and Sewer Division is responsible for managing the water and sewer systems. This
division currently has a water conservation program which helps to reduce the amount of water
used by residents. The water conservation program is part of their groundwater conservation
plan and includes an irrigation water use restriction to only one day a week between Memorial
Day and Labor Day.
Potential improvements to promote green infrastructure could include:
Providing educational materials about climate-suitable vegetation and landscaping that
can help to reduce the need to water.
Provide workshops for residential greenscaping.
3.3.6 Proposed Water and Sewer Division Programs
The Water and Sewer Division can help promote the implementation of green infrastructure
practices on private properties by developing new programs that provide incentives and
educational resources that will encourage homeowner and business participation. The
potential new programs that can be initiated under the Water and Sewer division are described
in Table 3-5.
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Table 3-5. Descriptions of Proposed New O&M Programs under the Water and Sewer Division
Program Description
Benefits
Limitations
Promote rainwater harvesting and
infiltration activities as part of the
groundwater conservation
program. Examples of potential
activities include expanding the
existing rain barrel distribution
program and holding rain garden
workshops.
Reduces the use of tap
water
Decreases stormwater
runoff
Potentially reduces
pollutants to the
stormwater drainage
system
May require additional staff
time and funding
Develop an incentives program for
to promote green infrastructure
for homeowners and/or
businesses. The program could
include installation financing,
which provides a refund of a
percentage of the installation cost
(or material cost) of green
practices (e.g., rain barrels).
Encourages green
infrastructure on private
property
Increases public
participation
Incentive programs can be
complex and costly to initiate
and administer
Incentives need to be
reasonable for the Town (i.e.,
appropriate for the Town's
budget) but significant enough
for the public to be willing to
participate
Recycling and Solid Waste Division
3.3.7 Existing Recycling and Solid Waste Division Programs
The Recycling and Solid Waste Division currently manages the collection of trash, hazardous
waste and leaves as well as the recycling of various materials including household items,
hazardous waste and yard waste. These green infrastructure programs help improve water
quality and reduce the opportunities for waste and other contaminants to enter the
stormwater systems.
Potential improvements to promote green infrastructure could include:
Providing educational materials on proper yard management, including composting
guidelines and application of pesticides and fertilizers (including timing, application
reduction and buffer areas), in residential mailings.
3.3.8 Proposed Recycling and Solid Waste Division Programs
The Recycling and Solid Waste Division can promote green infrastructure by developing new
composting programs, both for homeowners and the Town, that can further reduce the waste
and provide new sources of soil amendments for green infrastructure practices like
bioretention systems. Suggested new programs to support green infrastructure through the
Recycling and Solid Waste Division are provided in Table 3-6.
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Table 3-6. Descriptions of Proposed New O&M Programs under the Recycling and Solid Waste Division
Program Description
Develop a residential composting
program (i.e., distribution of
backyard composting bins and
related educational materials)
Benefits
Decreases food and yard
waste going into the
waste stream
Limitations
Requires homeowner interest
and maintenance
May attract pests, such as
raccoons
Parks and Grounds Division
3.3.9 Existing Parks and Grounds Division Programs
The Parks and Grounds division is responsible for managing the parks and open spaces in the
Town. Currently, they have a turf management program which utilizes zero phosphorus
fertilizer on all Town-owned properties, including both active and passive turf. A recent review
of the turf management program (HW, 2013a) indicated that this program has an annual total
phosphorus reduction of approximately 34 Ibs/year based on the type of fertilizer previously
used. In addition, the cost per pound of the phosphorus-free fertilizer is actually less expensive
per year than the conventional fertilizer by approximately $6,000.
3.3.10 Proposed Parks and Grounds Division Programs
New programs under the Parks and Grounds Division can help to integrate green infrastructure
practices, such as the use of pervious/porous pavers and native landscaping, into parks and
other available spaces where the community can gain first-hand experience and learn about
green infrastructure benefits. Table 3-7 describes the potential new programs that could be
implemented under the Parks and Grounds Division.
Table 3-7. Descriptions Proposed New O&M Programs under the Parks and Grounds Division
Program Description
Benefits
Limitations
Develop a park paths program
that promotes the construction
of walking paths and/or
sidewalks within and between
parks using green infrastructure
practices, such as permeable
pavement
Increases physical activity
Provides a potential for
interconnected parks for
pedestrians
Decreases maintenance to
fix footpaths
Slopes and/or landscape may
limit path length or width
Develop a native landscaping
program to promote the
installation of native plants and
trees in place of turf grass for
areas not used for specific
recreational purposes (e.g., ball
fields, soccer fields, etc.)
Reduces maintenance time
and related costs
Increases infiltration
potential, which reduces
ponding and flooding of
recreational areas
Space may be limited in some
parks
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Facilities Department
3.3.11 Existing Facilities Department Programs
The Facilities Department is responsible for the construction and maintenance of Town-owned
buildings needs. There are currently no existing programs that promote the use of green
infrastructure.
3.3.12 Proposed Facilities Department Programs
The Facilities Department can promote green infrastructure on Town-owned properties
through a new program that provides guidance for identifying green infrastructure
opportunities as well as coordinating with other departments for interdepartmental
opportunities. This program is described in detail in Table 3-8.
Table 3-8. Proposed New O&M Programs under the Facilities Department
Program Description
Benefits
Limitations
Develop a checklist for department
staff that identifies all potential
green infrastructure opportunities
for various types of facilities-related
needs, such as existing building
maintenance and repairs and new
building design and construction.
The checklist can also identify cross-
departmental green infrastructure
opportunities for site improvements.
Increase opportunities for
green infrastructure on
Town-owned properties
Requires coordination
between departments
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4.0 Policies
The Town of Franklin has several existing policies that help to support the use of green
infrastructure practices for stormwater management and help them meet their goals and
objectives as described in Section 1. However, some of the existing policies may also hinder or
conflict with green infrastructure goals. The recent review of Town's local codes identified
potential barriers and obstacles to green infrastructure implementation, as well as where
codes and policies could be strengthened (HW, 2013b). This section provides a discussion of
the regulatory drivers that influence policies as well as a summary of the policy review
conducted, including recommended revisions to the existing policies.
4.1 Regulatory Drivers
Local policies are often driven by requirements at the federal, state, and/or regional level. The
most influential likely being the federal Clean Water Act, which establishes a number of
permitting programs and policies at the national level for regulating discharges to surface
waters that then must be met at the state and local level. Sections 305(b) and 303(d) of the
federal Clean Water Act require states to monitor and report on the status of their waters as
well as develop a list of waterbodies that are not attaining or not expected to meet water
quality standards, often referred to as the "303(d) list." The Clean Water Act then requires that
states establish priority rankings for the waters on the 303(d) list and develop a Total
Maximum Daily Load (TMDL) for these waters. As is well documented, TMDLs have been
written and approved for the Charles River Watershed, which require substantial total
phosphorus reduction throughout the watershed. The Town of Franklin's share is
approximately 52% load reduction for stormwater-derived sources.
Franklin is currently operating under the extended 2003 MS4 permit; however, two new draft
general permitsthe "Small Municipal Storm Sewer Systems in the North Coastal Watershed"
(hereafter the MS4 General Permit) and the Residual Designation Authority (RDA) from
"Designated Discharges in the Charles River Watershed" (hereafter the RDA General Permit)
were issued by EPA in 2010. These two permits, as currently written, propose additional
control measures to meet phosphorus reduction targets through more effective stormwater
management of Franklin's MS4 and on individual private properties. Details on the draft
requirements can be found at www.epa.gov/regionl/npdes/stromwater/index.html.
The Town of Franklin has taken measurable steps towards meeting some of the anticipated
requirements of these new draft permits; however, there are a few additional requirements
that will require the Town to modify current practices. For example, the draft permits require
an evaluation of local development codes and street design standards to identify opportunities
for reducing impervious cover, integrating low impact development (LID), and removing
barriers to green stormwater infrastructure practices.
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4.2 Policy Review and Recommendations
Existing development codes can serve as a barrier to green infrastructure in a number of ways,
whether they are silent on, ambiguous towards, or in direct conflict with green infrastructure
principles. The recent review of the Town's policies, including local bylaws, regulations, plans
and guidelines, provides a vehicle to help identify which Town goals and objectives were being
hindered by the Town Codes and what approach could be used to address or remove the
barriers. The recommendations include specific actions that would best support the Town's
goals and objectives. A summary of the findings and recommendations is provided within the
subsections for each of the Town's goals for implementing green infrastructure.
4.2.1 Minimize Directly-Connected Impervious Area
There are several provisions in the Town's policies which act as barriers to minimizing directly-
connected impervious area. For example, the Town's Zoning Bylaws have minimum parking
and sidewalk requirements as well as minimum dimensions of drive aisles and parking spaces
(Sections 21 and 28). Similarly, the Town's Subdivision Rules and Regulations require minimum
roadway widths, turnaround dimensions and curbing. Neither of these codes provides
provisions for alternative materials, such as those mentioned in Section 2.4 in this report. To
support the Town's goal, it was recommended that these policies be updated to provide
flexibility in the required paving dimensions (e.g., reducing the minimum dimensions for
compact parking spaces) and materials for roads, parking lots and sidewalks. To promote green
infrastructure practices further, language should be added in the policies to encourage the use
of permeable materials where appropriate and the Town should provide more flexibility in
curbing to support the use of street-side green infrastructure practices. These provisions will
also help the Town to meet the potential regulatory requirements in the draft MS4 permit.
4.2.2 Preserve the Hydrologic Function of Natural Features
Although the Town has several policies which address site disturbance, these scarcely mention
specific standards to limit the disturbance or preserve natural features. For example, the
Town's Zoning Bylaws currently have no standards for minimum land disturbance, stabilizing
soils during construction, minimizing site grading or preserving existing landscaping (Section
23.C). The review recommended that specific standards be created to provide minimum or
maximum limits for site disturbance. For example, the Town should consider requiring
applicants to document that disturbed area is minimized to the maximum extent practical. To
preserve natural features, such as mature tree stands, it was recommended that applicants be
required to identify and preserve trees to the maximum extent possible and provide tree
protection measures at the drip line during construction. These standards will help to maintain
existing hydrologic patterns, including infiltration, which helps to support the Town's
groundwater recharge requirements.
4.2.3 Allow and Encourage Multi-Functional Stormwater Controls
The Best Development Practices (BDP) Guidebook is the primary guidance document that is
used to address stormwater management in the Town. While this document provides guidance
for the implementation of green infrastructure practices, it does not specifically use green
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infrastructure language, not all of the latest green infrastructure practices are included, and the
use of green infrastructure could be more strongly mandated. Similarly, the Design Review
Commission Design Guidelines does not reference the use of green infrastructure or the Town
goals and objectives when developing site layouts, site designs, landscaping, and other site
elements. It was recommended that the Town update the BDP Guidebook and other policies
with green infrastructure-specific language that allow and require the use of green
infrastructure practices to the maximum extent possible. In addition, the BDP Guidebook
should expand the available green infrastructure practices, such as including infiltration and
rainwater harvesting applications.
4.2.4 Increase Public Involvement, Education and Outreach
The Town currently has several existing programs that promote public involvement, education
and outreach that are conducted under the Town's existing MS4 permit. However, the Town
can strengthen these programs further by addressing the Town's objectives for this goal in
other policies and planning documents, such as the Open Space and Recreation Plan. Example
revisions to the Open Space and Recreation Plan include: providing signage at demonstration
projects; identifying specific properties that are key for phosphorus load reduction and using
them as demonstration areas; and installing rain gardens or rain barrels at existing recreation
areas for public outreach and education. By incorporating these objectives, the Town can help
to expand knowledge and support of green infrastructure practices in the community.
4.2.5 Address the Upper Charles River TMDL
The review of the existing Town policies found that there was no mention of the Upper Charles
River TMDL for phosphorus loading reduction target in any of the policies, nor were there any
standards in place to help the Town meet its goal. It is recommended that the phosphorus load
reduction target be mentioned in all guidelines and planning documents, including:
Section 31.D of the Zoning Bylaws,
Chapter 300 Section 9.B.2 of the Subdivision Rules and Regulations,
Section XIV of the Wetlands Regulations (Performance Standards),
Part II and II of the Design Review Commission Design Guidelines,
Sections 4.G and 8 of the Open Space and Recreation Plan, and
Sections I and II of the BDP Guidebook.
By incorporating specific language that is consistent and addresses Upper Charles River TMDL
as well as the Town's associated goals and objectives, it will make the Town's phosphorus
reduction target well known to the community and easier for developers to understand and
comply.
4.2.6 Provide Cost Effective Stormwater Management
The Town can address this goal through by removing potential barriers to green infrastructure
practices, strengthening existing policies to create clear and consistent standards, and
encouraging the use of green infrastructure in lieu of traditional stormwater infrastructure.
Green infrastructure can be more cost-effective than gray infrastructure because it is often
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cheaper to install, easier to maintain, and more effectively treats stormwater runoff. In
addition, it provides other social and economic benefits, such as enhanced neighborhood
aesthetics and reduced energy costs.
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5.0 Implementation Recommendations
5.1 A Vision for Green Infrastructure Implementation
As discussed throughout this document, green infrastructure is much more than a stormwater
management strategy; it has the potential to meet multiple Town objectives and cumulatively
save the Town, residents, businesses, and developers money. Perhaps the most important
recommendation for fostering more widespread implementation of green infrastructure in
Franklin would be for the Town to embrace these potential cumulative benefits and
implement an integrated program approach. In short, the Town will see the benefits when all
departments, elected and appointed officials, and the citizens of Franklin work towards a
common goal. Thus, the Town should consider adopting a Vision Statement as an early step in
implementation of a green infrastructure approach Town-wide.
5.2 Specific Recommendations for Implementing Project, Programs, and Policies
The following sections offer an approach to green infrastructure implementation across the
spectrum of activities. Several specific recommendations are offered ranging from changes to
existing codes, updating guidance documents, streamlining town communications, and
involving the Town's residents and business owners in the process. As discussed previously,
the Town is subject to a range of existing and proposed regulations that govern how new
development and redevelopment projects are implemented, how state-derived resources are
expended, and if the pending draft MS4 and RDA permits are enacted, how existing citizens and
businesses may be affected.
5.2.1 Implementing Green Infrastructure Projects
The following five recommendations are offered to provide a framework for implementation of
green infrastructure projects into the future:
1. Update Best Development Practices Guidebook to incorporate latest Green
Infrastructure practices and specifications. This is one of the more important steps the
Town might take to establish a consistent reference document for project proponents.
As discussed in previous sections, a revised manual could serve as both a guidance
reference for design, as well as a regulatory tool.
2. Convene a Town Green Infrastructure Committee to establish and update performance
standards (e.g., phosphorus reduction, runoff reduction, etc.). This committee would
likely serve the role of directing the update to the Best Development Practices
Guidebook as well as establishing a baseline for the Town's overall green infrastructure
program. Establishing performance goals for a range of projects will help the Town
achieve compliance with both existing and future permits. The Committee should
include Town decision-makers and interested stakeholders (e.g., Town Administrator,
Fire Chief, DPW Director, Town Planner, local developer, land-use attorney, etc).
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3. Update relevant codes to require the use of practices that meet minimum Green
Infrastructure performance standards. As stated previously, code modifications will
have a long-term impact on both public and private projects. The Town Green
Infrastructure Committee would presumably review and agree on key code changes that
can be implemented (e.g., revised road widths, parking standards, lots setbacks,
sidewalks, etc).
4. Develop and institute an inter-departmental Memorandum of Agreement (MOA) to
incorporate green infrastructure practices into new projects. Examples include new
schools and/or additions, fire and safety facilities, road resurfacing, and park amenities.
An MOA would serve to provide a common set of objectives for all new capital projects
and would help ensure a consistent approach to incorporating green infrastructure into
future projects.
5. Coordinate green infrastructure projects with on-going Massachusetts Department of
Environmental Protection (DEP) draft Sustainable Water Management Initiative (SWMI)
efforts. Under the SWMI framework, the Town is evaluating potential locations and
practices to promote infiltration to replenish groundwater levels and enhance
streamflow. The efforts to date have identified five preferred sites; a 30% design was
developed to retrofit a detention basin into an infiltration basin at Scarboro Court and
preliminary concept designs were developed for the other four locations.
5.2.2 Implementing Green Infrastructure Programs
The following two recommendations are offered to ensure that green infrastructure becomes
standard operating procedure across all of the Town's programs.
1. Prioritize the identified programs (see Section 3) for staged implementation; identify the
responsible party/department, costs, and implementation schedule. Section 3 identifies
a range of potential program enhancements. Not all of these should be treated equally,
as costs and potential benefits will vary. A Town Green Infrastructure Committee could
undertake this prioritization
2. Combine programs, where feasible, to minimize costs and maximize implementation.
As discussed previously, green infrastructure has a range of potential benefits, but also
involves costs for both capital projects as well as ongoing operations. The Town can
maximize the potential return on investment by combining programs. A few examples
include:
DPW Maintenance Programs (e.g., street sweeping, leaf litter pickup, catch
basin cleaning) updated to maximize pollutant removal and runoff reduction;
Town-wide Educational Program developed/refined to foster better
understanding of green infrastructure benefits and how residents and businesses
can benefit; and
Town-sponsored "build a rain-garden" program for residential property owners.
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5.2.3 Implementing Green Infrastructure Policies
Depending on the regulatory drivers and timing for implementation of these, new policies may
be necessary. In the short-term, it makes sense to begin the process of how the Town might
develop and implement a Town-wide Phosphorus Control Plan (PCP). The initial elements
would likely include convening a PCP subcommittee, identifying the methods and locations for
controls, and quantifying load reduction from various strategies. The Town Green
Infrastructure Committee, cited above, could undertake this task.
The recommendation to convene a Town Green Infrastructure Committee could review the
identified opportunities to strengthen existing policies and prioritize recommendations.
Particular emphasis might be on those policies that would impact major projects such as the
"Downtown Franklin Roadway and Streetscape Improvement Project." The following table is
offered to illustrate examples of what the Committee might address related to prioritizing
projects, programs, and policies for green infrastructure implementation.
Table 5-1. Example Format for Prioritizing Identified Opportunities to Strengthen Green Infrastructure
in the Town of Franklin
Green Infrastructure
Project/Program/Policy
Example Regulatory
Barriers
Why should this be part of the
Town's Green Infrastructure
Strategy?
Pre-treatment, Treatment and
Infiltration Practices (e.g., filter
strips, bioretention cells, rain
gardens, infiltration trenches)
Curbing, street design,
landscaping, and parking
standards
The requirements often include
minimum standards that prohibit a
hydrologic connection of the target
impervious area to the practice,
such as "a curb of at least four
inches in height must surround all
landscaped islands."
Rain Harvesting (e.g., rain
barrels, cisterns)
Dimensional standards
(yards, lot coverage),
plumbing codes
Dimensional standards could
prohibit rain barrels or cisterns from
encroaching into required setback
areas; plumbing codes could require
downspouts to be connected to the
stormwater collection system.
Alternatives to Impervious Cover
(e.g., pavers, porous concrete)
Roadway and parking lot
material specifications
The specifications can require that
roadways and parking lots be
constructed of impervious materials.
Advanced systems (e.g., green
roofs)
Dimensional standards
(building height)
Dimensional standards, such as
maximum building height, can limit
the height of green roofs.
Non-structural practices (e.g.,
impervious cover reduction, tree
plantings, open space
protection)
Dimensional standards (lot
size, frontage, yards), parking
standards, landscaping
standards, street design
requirements, open space
requirements
All of these requirements relate to
the amount of impervious cover
required either directly or indirectly,
or on the contrary, how many trees
or how much open space protection
is required.
Green Infrastructure Implementation Strategy-Town of Franklin
5-3
March 2014
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Green Infrastructure Implementation Strategy -Town of Franklin 5-4
March 2014
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6.0 References
Benedict, Mark A and E. T. McMahon. 2001. Green Infrastructure: Smart Conservation for the
21st Century. The Conservation Fund Sprawl Watch Clearinghouse Monograph Series.
36pp.
Center for Neighborhood Technology (CNT). 2010. The Value of Green Infrastructure: A Guide to
Recognizing Its Economic, Environmental and Social Benefits. 80 pp.
Center for Watershed Protection (CWP). 2013. Watershed 101: Stormwater Management.
Retrieved from http://www.cwp.org/vour-watershed-101/stormwater-
management.html on 23 January 2013.
Horsley Witten Group, Inc. (HW). December 4, 2012. EPA Region 1 Green Infrastructure
Partnership with the City of Chelsea: Technical Support Document to Assist the City to
Further Encourage and Promote the Use of Green Infrastructure. 29pp. Retrieved from
http://www.chelseama.gov/Public Documents/Chelsea MA Planning/PublicationsFolde
r/EPAGI/ChelseaGI TD Final.pdf on 30 March 2014.
Horsley Witten Group, Inc. (HW). February 16, 2013(a). Quantification of Benefits from Existing
Green Infrastructure Projects - Town of Franklin, MA. Memorandum from Rich Claytor
and Michelle West, HW to Brutus Cantoreggi, Franklin DPW. 11 pp.
Horsley Witten Group, Inc. (HW). March 29, 2013(b). Code Review to Promote Green
Infrastructure- Town of Franklin, MA. Memorandum from Rich Claytor and Michelle
West, HW to Brutus Cantoreggi, Franklin DPW. 13 pp.
Schueler, T., D. Hirschman, M. Novotney, and J. Zielinski. 2007. Urban Subwatershed
Restoration Manual No. 3 - Urban Stormwater Retrofit Practices (Version 1.0). Center for
Watershed Protection. 240 pp.
Town of Franklin. February, 1997. Town of Franklin 1997 Master Plan. Retrieved from
http://franklinma.virtualtownhall.net/Pages/FranklinMA Planning/initiatives/master/in
dex on 23 January 2013.
United States Environmental Protection Agency (US EPA). 2013. Water: Green Infrastructure.
Retrieved from http://water.epa.gov/infrastructure/greeninfrastructure/index.cfm on
23 January 2013.
Green Infrastructure Implementation Strategy -Town of Franklin 6-1
March 2014
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Horsley Witt en Gimrp
Sustainable Environmental Solutions IPk ^
90 Route 6A Sandwich. MA 025B3 ^
Tel: 508-833-6600 Fax:508-833-3150 vrwwhorsleymttencom K.
MEMORANDUM
TO: Brutus Cantoreggi, Franklin DPW
FROM: Rich Claytor and Michelle West, Horsley Witten Group
DATE: February 26, 2013
RE: Quantification of Benefits from Existing Green Infrastructure Projects-Town of
Franklin, MA
This memorandum presents findings by the Horsley Witten Group (HW) from a review of six
stormwater management projects within the Town of Franklin, MA. The purpose of the review
is to quantify the benefits from these existing green infrastructure (Gl) projects in order to help
guide the development of a town-wide Gl Implementation Strategy. The analysis specifically
focused on phosphorus reduction to help the Town understand how best to address the Charles
River TMDL requirements, but other benefits were evaluated as well.
This memorandum was developed under EPA contract no. EPA-C-11-009 as one of the 2012 EPA
Green Infrastructure Community Partner Projects. HW developed the memorandum under
subcontract to Tetra Tech, Inc.
METHODS
Plans, calculations, and stormwater reports provided by the Town were used to gain an
understanding of the projects. From this material, key information was compiled and/or
determined, including type of practice used, land use, drainage area, impervious cover, and
treatment volume provided (0-1 inch). Using this information and EPA Region 1 guidance
developed for the draft Residual Determination Authority (RDA) General Permit (US EPA, 2010),
phosphorus loading was established for each particular drainage area. Table 1 provides the
phosphorus loading rates used for this project based upon land use and broken down by
impervious and pervious area.
BMP Performance Curves (Tetra Tech, 2009) were used to calculate phosphorus removal rates
based upon treatment storm, and where applicable, soil infiltration rate (practices such as
bioretention and rain gardens are not categorized by soil infiltration rate). Where bioretention
were used as pretreatment for infiltration practices, the infiltration phosphorus removal rate
from the appropriate performance curve was assumed. For those projects that involved a
Quantification of Benefits from Existing Gl Projects - Town of Franklin Page 1
Horsley Witten Group, Inc. February 26, 2013
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reduction of impervious cover, the corresponding phosphorus loading reduction was
determined as the difference between impervious and pervious loading values for the
applicable land use (see Table 1).
The BMP Performance Curves were also used to calculate an estimate of the amount of annual
runoff reduction provided by each practice. Runoff reduction occurs with infiltrating practices;
the percentage of reduction is based upon design soil infiltration rates (Rawls et al., 1982)
determined by soil texture/NRCS Hydrologic Group.
Table 1. Phosphorus Loading as Function of Land Use (US EPA, 2010]
Land Use
Agriculture
Commercial
Forest
Freeway
High-density Residential
Industrial
Low-density Residential
(rural)
Medium-density
Residential
Open Space
Composite P Load
Rate (CPLE)
(Ibs/ac/yr)
0.45
1.50
0.12
0.80
1.00
1.30
0.27
0.50
0.27
Land
Surface
Cover
Pervious
Impervious
Pervious
Impervious
Pervious
Impervious
Pervious
Impervious
Pervious
Impervious
Pervious
Impervious
Pervious
Impervious
Pervious
Impervious
Pervious
P Load Export (PLE) Rate by
cover (Ibs/ac/yr)
0.45
2.23
0.27
0.89
0.09
1.34
0.27
2.23
0.27
1.78
0.27
0.89
0.13
1.34
0.27
0.89
0.22
PROJECT DESCRIPTIONS
The Town of Franklin, with input from HW, selected six representative Town Gl projects for
assessment of benefits. The selected projects represent a variety of Gl work currently being
done within Franklin. A description of each project is included below, with a summary of key
information provided in Table 2. A summary of each project's annual phosphorus and runoff
reduction benefits can be found in Table 3.
Quantification of Benefits from Existing Gl Projects -Town of Franklin
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February 26, 2013
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Table 2. Summary of Key Information for the 6 Reviewed Projects
Project Name
Lockewood Drive
Panther Way
Wachusett
Street
Wyllie
Road/
Miller
Street
Small
Fletcher Lot
Parmenter
School-1
Parmenter
School-2
Miller at
Green
Wyllie Rd
Greensfield Road
Town Property - P-f ree
Fertilizer
Type of
BMP(s)
Bioretention,
Infiltration
Basin
Infiltration
Basin
Bioretention
Bioretention
Bioretention,
Infiltration
Chambers
Bioretention,
Infiltration
Chambers
Infiltration
Chambers
Rain Garden,
Pavement
Reduction
Zero P
Fertilizer
Drainage
Area (ac)
22.00
27.61
5.80
1.05
1.05
37.52
9.68
0.10
120.00
Impervious
Cover (ac)
4.68
10.22
1.90
0.57
0.57
5.10
1.70
0.10
0.00
Treatment
Storm (in)
0.48
0.60
0.09
0.25
1.00
0.38
1.00
0.60
NA
Infil.
Rate
(in/hr)
0.27
1.02
1.02
0.27
0.27
2.41
2.41
2.41
NA
Land Use
Medium-
density
Residential
Medium-
density
Residential
Medium-
density
Residential
Commercial
Commercial
Medium-
density
Residential
Medium-
density
Residential
Open Space
Table 3. Annual Total Phosphorus (TP) and Runoff Reduction from the Reviewed Projects
Project Name
Lockewood Drive
Panther Way
Wachusett
Street
Wyllie Road/
Miller Street
Small Fletcher Lot
Parmenter School-1
Parmenter School-2
Miller at Green
Wyllie Rd
Greensfield Road
Town Property -P-free Fertilizer
Totals:
TP Loading
to Facility
(Ibs/yr)
10.95
18.39
3.60
1.40
1.40
15.59
4.44
0.13
34
91.5
TP Removed By
Impervious
Reduction (Ibs/yr)
NA
NA
NA
NA
NA
0.08
NA
0.21
NA
0.29
TP Removed
By BMP
(Ibs/yr)
7.90
15.45
0.65
0.53
1.40
11.64
4.26
0.08
34
75.92
Annual
Runoff
Reduction
56%
77%
21%
34%
82%
70%
94%
84%
0%
Quantification of Benefits from Existing Gl Projects -Town of Franklin
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February 26, 2013
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Lockewood Drive:
Lockewood Drive is located in a medium-density residential neighborhood off King Street,
southeast of downtown. Stormwater from this neighborhood (22 acres, 21% impervious) was
originally directed into a dry "detention pond" with an at-grade outlet pipe, which resulted in
modest detention at best and little treatment of the runoff. In 2011, this existing basin was
modified to increase treatment, recharge, and storage. Franklin Engineering staff designed the
retrofit, a contractor was hired with grant funds for the initial excavation, and then the project
was finished by DPW and Engineering staff. The retrofit included a plunge pool, sediment
forebay, bioretention cell, and infiltration basin constructed in HSG C soils.
No BMP details or design plans were created for this project, but the Town provided an as-built
plan and the design calculations. To analyze the benefits of the retrofit, HW interpolated the
volume of the bioretention cell based on the given media depth and the volumes of the
adjacent infiltration basin and sediment forebay (see Figure 1). The bioretention cell was
assumed to have no underdrain, with any overflows going into the infiltration basin; thus, the
volumes were added together, treating it as a large infiltration basin. The treatment storm
provided was calculated at 0.48 inches.
Figure 1. Excerpt from As-built Plan Prepared for the Lockewood Drive Stormwater Retrofit.
27 INV=347.4
SPILLWAY
ELEV.-345.I
\ \
STONE-LINED
CUWNEk
BIOREJENTION 'CELL
BOT. ELEV-342.1
(APPROX. 2' OF
BIORETENTION F,ILL
MATERIAL)
EDIMENTATION BASIN I .
CAPACITY=2,266 CF | \
(1700cf REQ.'D)
BOT. ELEV. =342.
INFILTRATION^ BASIN
CAPACITY=5,6&6 CF
(4250cf REQ.'D)
BOT: ELEV=338.8
_ - ELEV.=344.3
-TOP OF GABIONS
ELEV.=342.1
TOP OF WEIR
Panther Way:
Panther Way is located off West Central Street, which is to the northwest of downtown, and
provides access to the high school. The surrounding land use in this area is medium-density
residential. A new Stormwater BMP was installed near the police station to manage runoff
from its parking lot and from the existing storm sewer system on Highwood Drive
(condominium development with no prior Stormwater management). A diversion manhole,
sediment forebay, and infiltration basin were constructed to relieve existing flooding issues and
to provide water quality treatment and recharge before discharging into an unnamed stream
Quantification of Benefits from Existing Gl Projects -Town of Franklin
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February 26, 2013
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that feeds Mine Brook, a tributary of the Charles River. Over 27 acres (37% impervious) drain
to this new infiltration basin, which was sized to treat the 0.6-inch storm in HSG B soils.
Figure 2. Excerpt from the Scanned Plans for the Panther Way Infiltration Basin.
40
HASIN 7ROH1.K
Wachusett Street:
Wachusett Street is located south of downtown, connects King and Cottage Streets, and has
significant traffic volumes during certain times of day for both Parmenter School and Fletcher
Field. The surrounding land use is a mix of medium-density residential and commercial.
Stormwater management work was done as a part of the recent Wachusett Street
Improvements project, including installation of facilities in two sub-watersheds. At the small
Fletcher Field Lot, catch basins were installed to redirect flow from Arlington and Wachusett
Streets into a bioretention area with a sediment forebay. At Parmenter School, four
bioretention areas and two sets of underground infiltration chambers were installed to provide
treatment to runoff associated with the school, its parking lots, and a portion of Wachusett
Street. These locations and practices were chosen for their high visibility, which makes them
excellent demonstration projects for educating the public about stormwater.
The designs of these features were based on concepts developed by the Charles River
Watershed Association (CRWA, 2009), but no final sizing calculations or details were created by
the Town; the size of the systems was based on the space available. Plans provided by the
Town of Franklin and the CRWA report were used to determine approximate drainage areas
and treatment volumes, using static calculation methods for the infiltration chambers. The
analysis divided the BMPs into two main categories: Fletcher Lot Bioretention (drainage area of
5.8 acres, 33% impervious) and Parmenter School Bioretentions/lnfiltration Chambers (drainage
area of 2.1 acres, 54% impervious). For the Parmenter School bioretention practices, it was
assumed that half the drainage area was flowing to the two locations in the parking lot (with no
infiltration chambers), and the remaining half flowed into the two bioretentions that
discharged to infiltration chambers.
Quantification of Benefits from Existing Gl Projects -Town of Franklin
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Figure 3. Excerpt from the scanned plans for the Wachusett Street Improvement Project, showing two
bioretention areas and underground infiltration.
Wyllie-Miller:
Wyllie Road and Miller and Green Streets are located in medium-density residential areas in the
northeast portion of Franklin. Stormwater management projects were designed in this area as
a part of a grant project. The first portion of the project, completed in 2012, involved
retrofitting the storm sewer system on Wyllie Road to discharge to underground infiltration
chambers at the cul-de-sac (see Figure 4). The drainage area to the infiltration chambers is 9.7
acres with over 17% impervious cover, and the treatment storm depth is one inch. The second
portion of the project, scheduled to be completed in 2013, will involve replacing pavement with
grass cover, a rain garden, and underground infiltration chambers at the intersection of Miller
and Green Streets. This project will be able to treat 0.38 inches of runoff over a 37.5-acre
drainage area with 14% impervious cover, and has the added benefit of less pavement to
maintain in the long run.
Figure 4. Photos taken during the construction of underground infiltration chambers on Wyllie Road.
Quantification of Benefits from Existing Gl Projects -Town of Franklin
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Greensfield Road:
Greensfield Road is a relatively short, dead-end road off Lincoln Street in the northeastern
portion of Franklin. The road provides access to a medium-density residential neighborhood.
Overtime, a spur road was added to the original cul-de-sac, leaving unnecessary pavement. In
2012, the Franklin DPW removed the excessive pavement (0.21 acres), replacing the impervious
cover with grass (see Figure 5). In addition, a small rain garden was installed to treat runoff
from the contributing roadway area (0.1 acres).
Figure 5. Excess pavement from an unnecessary cul-de-sac was removed (left); DPW staff installed a
rain garden to manage some of the remaining road runoff (right).
Town Property- Phosphorus-free Fertilizer:
In 2008, the Town of Franklin began using zero phosphorus fertilizer on all Town-owned
property, which includes turf that is both active (e.g., sports fields) and passive (e.g., lawn
around buildings and in parks). Prior to 2008, Franklin spread fertilizer with 5% phosphate (or
roughly 2% phosphorus) on these areas multiple times a year (see breakdown attached to this
memo). To determine the annual reduction of phosphorus discharged to Franklin's surface
waters that resulted from this change in fertilizer use, it was necessary to calculate how much
of the phosphorus from the fertilizer was lost to runoff versus being taken up by the grass and
bound in the soil. This value is highly variable based on type of vegetation and site-specific soil
characteristics. However, an empirical relationship for average annual phosphorus loss to
runoff from fertilizer was developed by Vadas et al., 2009. This equation is based upon the
amount of annual runoff vs. precipitation expected (based on runoff coefficient), total quantity
of fertilizer used (unincorporated into the ground), and an empirical factor. Using this
equation, it was determined that roughly 2% of the phosphorus applied as fertilizer in this area
will run off to nearby storm sewers and surface waters. This was used as the phosphorus
reduction estimate.
RESULTS
Costs received from the Town were used to quantify the cost of phosphorus removal by giving a
dollar amount to the pounds of phosphorus removed annually. When stormwater practices
Quantification of Benefits from Existing Gl Projects -Town of Franklin
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February 26, 2013
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were a part of a larger construction project, only the estimated cost for the stormwater portion
was used for this analysis. The costs are summarized below in Table 4. These results will be
used to help the Town develop the most cost-effective Gl implementation strategy.
Table 4. Cost of Phosphorus Removal for the Reviewed Projects
Project Name
Lockewood Drive
Panther Way
Wachusett
Street
Wyllie Road/
Miller Street
Small Fletcher Lot
Parmenter
School-1
Parmenter
School-2
Miller at Green
Wyllie Rd
Greensfield Road
Town Property - P-free Fertilizer
Total:
Type of
BMP(s)
Bioretention,
Infiltration
Basin
Infiltration
Basin
Bioretention
Bioretention
Bioretention,
Infiltration
Chambers
Bioretention,
Infiltration
Chambers
Infiltration
Chambers
Rain Garden,
Pavement
Reduction
Phosphorus-
free Fertilizer
NA
TP
Reduction
(Ib/yr)
7.90
15.45
0.65
0.53
1.40
11.72
4.26
0.29
34
76.2
Project
Cost
$13,000
$75,388
$71,612
$122,000
$112,289
-$10,000
-$5,978
$378,311
Cost of TP
Reduction
($/lb/yr)
$1,645
$4,880
$27,768
$10,409
$26,363
-$34,634
-$173
$4,964.71
From Table 4, the total TP reduction for all six BMP projects is 76.2 pounds, with an average
cost per pound of $4,964.71. After removing the non-structural project (the phosphorus-free
fertilizer), the average cost per pound of TP reduction is $9,106.37 for structural stormwater
projects. The Town may be able to use this average cost for future planning-level estimation
purposes. In addition, it is important to note that the five structural stormwater projects result
in a 75.5% reduction in phosphorus loading from their drainage areas. As a reference, the
General Permit (US EPA, 2010) calls for a 52.1% phosphorus load reduction town-wide to meet
the total maximum daily load (TMDL), which is the equivalent of 2,828 Ibs/year for the Town of
Franklin. However, in a recent evaluation that looked at TMDL costs in Franklin (HW et al.,
2011), it was assumed that 15% of the load reduction could be met by non-structural practices.
This leaves 37.1% (2,013.80 Ibs/yr) to be removed by structural practices. Using the average
cost per pound from Table 4, the cost estimate for implementing the total necessary structural
controls is around $18.3 million vs. $74.6 million from the recent study. The average cost
presented here is from a limited review of projects and likely represents the extreme low-end
Quantification of Benefits from Existing Gl Projects -Town of Franklin
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estimate of the total cost of structural controls for meeting the phosphorus TMDL. These are
projects that were likely done first due to their lower costs and easy implementation (e.g., open
space available, easy retrofits, town-owned property, etc.). However, the Town can use these
examples to formulate a cost-effective plan for reducing phosphorus loading per the TMDL. A
discussion of the notable trends that emerged from the review of the six projects is included
below.
The most conspicuous results shown in Table 4 are the negative costs per pound of annual TP
removed for the Greensfield Road and the phosphorus-free fertilizer projects. The Greensfield
Road project shows a negative cost due to the net savings incurred by the DPW because they
did not need to repave the former cul-de-sac. This will continue to be a savings every time the
rest of the road needs to be repaved. The cost per pound of TP reduction for the phosphorus-
free fertilizer initiative is also a negative number because the fertilizer without phosphorus is
less expensive. It should be noted that the greatest total phosphorus reduction of all six
projects was achieved by the Town changing the fertilizer it uses; the statewide ban on using
phosphorus-containing fertilizers will expand these benefits to non-municipal properties
starting January 1, 2014. Gl Projects that save money as well as remove phosphorus should be
the highest priority projects that the Town would want to pursue in their long-term strategy. In
particular, the Town should consider pavement reduction whenever feasible for future repaying
projects for the most cost-effective phosphorus removal.
Another pattern is related to the type of labor. Projects done "in-house" by DPW, such as
Lockewood Drive, tend to have a lower dollar amount per pound of TP removed; those done by
outside contractors, such as Wachusett Street, have a higher cost. It should be noted that
salary, benefits, and overhead were not included in this review, which would raise the cost.
Even so, the Town should design and construct projects in-house when feasible for the most
return on their investment. In-house projects have the additional benefits of on-the-job
training for staff about Gl and creating a sense of ownership for the Gl projects, which can lead
to better maintenance.
In addition, the type of stormwater practice installed has a large impact on cost effectiveness.
Table 4 clearly shows that infiltration basins cost much less per pound of phosphorus removed
than their underground counterparts, infiltration chambers. This is due to the need for more
associated infrastructure and materials required for the underground systems. Thus, the Town
should try to install surface practices to the extent possible, depending on the surrounding land
use and when the space is available.
Finally, the size of the stormwater practice can affect the cost of phosphorus removal. As a rule
of thumb, a stormwater BMP may not be worth installing if it treats less than 0.25 inches. This
is supported by the fact that the Wachusett Street project has the highest cost of phosphorus
removal; the majority of the drainage area (almost 90%) is treated by the small Fletcher lot and
Parmenter School(l) bioretention areas, which treat the 0.09-inch and 0.25-inch storms,
respectively. This reduced cost effectiveness may have to do with the fact that much of the
cost of stormwater practices involves conveyance into and out of the BMP. These costs remain
Quantification of Benefits from Existing Gl Projects - Town of Franklin Page 9
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basically the same regardless of the size. While the Wachusett Street project had the added
benefit of public education, in general, the Town should focus efforts on the retrofits that can
treat at least 0.25-inches of runoff from the contributing drainage area.
Other Associated Benefits
Gl projects offer many significant benefits in Franklin besides the reduction of phosphorus
loading to the Charles River. While not specifically analyzed in this review, these projects also
reduce a suite of other pollutants such as sediment, nitrogen, hydrocarbons, metals, and
bacteria. Phosphorus is a nutrient that adsorbs easily to particulates; thus, one would expect a
close correlation between the phosphorus load reduction of a given project and the removal of
other particulate-based pollutants (e.g., sediment, hydrocarbons, and metals). Bacteria
removal does not follow the same pollutant removal pathways; however, infiltrating practices
are known to have the best bacteria removal capability. Gl projects tend to incorporate runoff
reduction through infiltration, so bacteria load reduction would be another important benefit.
Through review of the selected projects, annual runoff reduction rates were also calculated
where applicable. By reducing the annual runoff, infiltrating Gl practices help lessen the load
on storm sewer systems and downstream water resources, which reduces maintenance costs
and streambank erosion issues. Practices not specifically designed for infiltration still help to
decrease runoff through evapotranspiration. In some cases, such as on Panther Way, the Gl
practice also helps address existing flooding issues, adding the benefit of public safety and
reduction of property damages.
In general, maintenance costs tend to be lower with above-ground stormwater management
systems, such as bioretention facilities, due to easier access and the mostly landscape-related
activities. The very nature of being visible also helps to ensure that routine inspections occur;
thus, improving the overall maintenance and effectiveness of the practice. As mentioned
above, the Town also saves money on the future maintenance for those Gl projects where
pavement was reduced. This is a recurring savings every life cycle of the remaining pavement.
There are a number of other benefits that are not easily quantified but important to the Town
of Franklin. Gl seeks to mimic natural hydrology and incorporate native vegetation as the
primary means of managing stormwater. Because of this, many typical Gl-influenced
stormwater systems also provide increased habitat and a greater wildlife biodiversity compared
to traditional stormwater practices. This tends to reduce nuisance species, such as mosquitoes,
by providing habitat for natural predators. In addition, since many Gl practices incorporate
vegetation, such facilities can provide green spaces for the public to enjoy. This leads to unique
opportunities for education and outreach features, helping to increase the awareness of
stormwater and its impacts. These benefits can be hard to find in many suburban
environments. Finally, property values typically increase when they abut landscaped, open
areas versus abutting uninterrupted paved areas such as parking lots and streets. This can also
help attract new home and business owners to the town, improving the economy.
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REFERENCES
Charles River Watershed Association (CRWA). 2010. Stormwater Management Plan for Spruce
Pond Brook Subwatershed. Prepared for Town of Franklin. Jesse B. Cox Charitable Trust Fund.
Charles River Watershed Association (CRWA). 2011. Final Total Maximum Daily Load for
Nutrients in the Upper/Middle Charles River Basin, Massachusetts. CN 272.0. Prepared for MA
DEP and US EPA Region 1, New England.
http://www.mass.gov/dep/water/resources/ucharles.pdf
Horsley Witten Group, Inc. and AMEC Earth & Environmental, Inc. 2011. Sustainable
Stormwater Funding Evaluation for the Upper Charles River Communities of Bellingham,
Franklin, and Milford, MA. Prepared for US EPA Region 1, New England.
Rawls, W.J., D.L. Brakensiek, and K.E. Saxon. 1982. Estimation of Soil Water Properties.
Transactions of the ASAE 25:5:1316-1320, 1328.
TetraTech. 2008. Stormwater Best Management Practice Performance Analysis. Appendix B.
US EPA. 2010. Draft General Permit for Residually Designated Discharges in Milford, Bellingham,
and Franklin, Massachusetts. Appendix D, Table 2-1. Available at:
http://www.epa.gov/regionl/npdes/charlesriver/index.html
Vadas, P.A., L.W. Good, P.A. Moore, Jr., and N. Widman. 2009. Estimating Phosphorus Loss in
Runoff from Manure and Fertilizer for a Phosphorus Loss Quantification Tool. Journal of
Environmental Quality 38:1645-1653.
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