FDC PHASE 2, TASK ORDER B
NEXT-GENERATION WATERSHED
MANAGEMENT PRACTICES FOR
CONSERVATION DEVELOPMENT
FINAL REPORT - October 2022
Prepared for:
U.S. Environmental Protection Agency, Region 1 (EPA Rl)
Prepared by:
Great Lakes Environmental Center, Inc.
Waterstone Engineering
Paradigm Environmental
JVL Planning
Funded by:
Blanket Purchase Agreement: BPA-68HE0118A0001 -0003
Requisition Number: PR-R1-21-00225
Order: 68HE0122F0003
WATERSTONE
ENGINEERING
INNOVATIVE 5~ORMWATER MANAGEMENT
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19, 2022
FINAL REPORT
ON
FDC PHASE 2, TASK ORDER B:
NEXT-GENERATION WATERSHED MANAGEMENT PRACTICES
FOR CONSERVATION DEVELOPMENT
Prepared for:
U.S. Environmental Protection Agency, Region 1 (EPA Rl)
Submitted By: Great Lakes Environmental Center, Inc.
Waterstone Engineering
Paradigm Environmental
JVL Planning
October 19, 2022
Blanket Purchase Agreement: BPA-68HE0118A0001-0003
Requisition Number: PR-R1-21-00225
Order: 68HE0122F0003
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19, 2022
Table of Contents
Acknowledgments 4
1. Introduction 5
1.1. Project Team 6
1.2. Funding Statement 8
2. Municipal Engagement Process 9
2.1. Municipal Engagement Working Meetings 9
2.2. SNEP Webinar 9
3. Concept Development Plans for Hypothetical New and Redevelopment Projects 10
3.1. Concept Development Plans: Overview and Results 12
3.1.1. Concept Development Plan 1 13
3.1.2. Concept Development Plan 2 18
3.1.3. Concept Development Plan 3 23
4. Municipal Regulatory Audits, Review, and Recommendations 28
4.1. Local Bylaw Review 28
4.2. MA Audubon - Municipal Zoning By-Laws, Subdivision and Site Plan Review Regulations,
and Stormwater Audit Tool And Overview 28
4.3. Regulatory Audit Profiles - Easton, Mansfield, Middleborough 30
4.3.1. Easton Regulatory Audit Results (See Appendix F for full checklist) 31
4.3.2. Mansfield Regulatory Audit Results 32
4.3.3. Middleborough Regulatory Audit Results 33
4.4. Recommended Zoning By-Laws and Regulations Amendments for Watershed Protection34
4.4.1. Municipal Stormwater By-Law and Land Development Standards 34
4.4.2. Stormwater Management General Application Requirements 35
4.4.3. EPA NPDES MS4 Permit Inspection Requirements 37
4.4.4. Water Quality and Watershed Health and Function 38
4.4.5. Climate Change Standards and Requirements 41
4.5. Development of a Watershed Protection Standard for New and Redevelopment Projects. 43
5. Compendium of Site-Development Stormwater Management Solutions for Water Resource
Protection 46
Appendix A. CoverMunicipal Meeting # 1 - December 18, 2021
Appendix B. Municipal Meeting #2 - June 30, 2022
Appendix C. Municipal Meeting #3 - September 13, 2022
Appendix D. Southern New England Program (SNEP) Webinar - September 29, 2022
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Appendix E. Concept Development Plans for High Density Residential, Commercial Rede-
velopment, and Low Density Residential
Appendix F. Bylaw Review Checklist for the Town of Easton, MA
Appendix G. Methodology for the Development of a Watershed Protection Standard
Appendix H. Compendium of Site-Development Stormwater Management Solutions for Wa-
ter Resource Protection
List of Tables
Table 1. Summary of Concept Development Plans 13
Table 2: Summary statistics of estimated annual runoff and groundwater recharge volumes for unit
area predevelopment conditions by hydrologic soil groups (HSG) for Boston, MA climatic conditions
(1990-2022) 44
Table 3: Watershed protection standard for impervious cover stormwater management: Infiltration
SCM design storage volumes (DSVs) to achieve predevelopment groundwater recharge and SW
nutrient load export 44
List of Figures
Figure 1. Concept Development Plan 1 (CD1) for High Density Residential under 3 Scenario: No
Controls, Minimum LID, LID for Watershed Protection Standard 14
Figure 2. Concept Development CD1.2 No Controls for High Density Residential 14
Figure 3. Concept Development CD 1.3 MADEP LID for High Density Residential 15
Figure 4. Concept Development CD1.4 LID to Achieve the Watershed Protection Standard for High
Density Residential 16
Figure 5: Water Quality Performance and Costing for CD1.3 Minimum LID and CD1.4 LID to
Achieve the WPS for High Density Residential 16
Figure 6: Runoff Duration Curves for CD1.3 Minimum LID and CD1.4 LID for High Density
Residential 17
Figure 7: Climate Resiliency Performance for CD 1.3 Minimum LID and CD 1.4 LID for High Density
Residential 17
Figure 8. Concept Development Plan 2 (CD) for Commercial Redevelopment Residential under 3
Scenario: No Controls, Minimum LID, LID for Watershed Protection Standard 18
Figure 9. Concept Development CD2.2 No Controls for Commercial Redevelopment 19
Figure 10. Concept Development CD2.3 MADEP LID for Commercial Redevelopment 20
Figure 11. Concept Development CD2.4 LID to Achieve the Watershed Protection Standard for
Commercial Redevelopment 21
Figure 12: Water Quality Performance and Costing for CD2.3 Minimum LID and CD2.4 LID to
Achieve the WPS for Commercial Redevelopment 21
Figure 13: Runoff Duration Curves for CD2.3 Minimum LID and CD2.4 LID for Commercial
Redevelopment 22
Figure 14: Climate Resiliency Performance for CD2.3 Minimum LID and CD2.4 LID for
Commercial Redevelopment 22
Figure 15. Concept Development Plan 3 (CD3) for Low Density Residential under 3 Scenario: No
Controls, Minimum LID, LID for Watershed Protection Standard 23
Figure 16. Concept Development CD2.2 No Controls for Commercial Redevelopment 24
Figure 17. Concept Development CD3.3 MADEP LID for Low Density Residential 25
Figure 18. Concept Development CD3.4 LID to Achieve the Watershed Protection Standard for Low
Density Residential 26
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FDC Phase 2, Task Order B: Next-Generation Watershed Final Report
Management Practices for Conservation Development October 19. 2022
Figure 19: Water Quality Performance and Costing for CD3.3 Minimum LID and CD3.4 LID to
Achieve the WPS for Low Density Residential 26
Figure 20: Climate Resiliency Performance for CD3.3 Minimum LID and CD3.4 LID for Low
Density Residential 27
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ACKNOWLEDGMENTS
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19, 2022
1. INTRODUCTION
This report was prepared as part of a second phase and continuation of EPA's Flow Duration Curve
(FDC) project entitled, Holistic Watershed Management for Existing and Future Land Use Develop-
ment Activities: Opportunities for Action for Local Decision Makers: Phase 1 - Modeling and Devel-
opment of Flow Duration Curves (FDC1 Project). EPA's second phase FDC project employs two
separate but related task orders. The report here is based on FDC2 Task Order B: Next-Generation
Watershed Management Practices for Conservation Development.
The Next-Generation Watershed Management Practices for Conservation Development project is
about envisioning a different future of watershed management. The project will evaluate a range of
new and redevelopment (nD/rD) approaches to better understand and communicate the future impact
upon watersheds and the potential for enhanced site design and management for optimal sustainability
and resilience. This includes examining green infrastructure practices, the minimization, reduction
and removal of existing impervious cover, and next-generation municipal bylaws / ordinances.
This project examines headwater stream segments in the Taunton River Watershed to understand the
impacts of, and potential approaches for managing impervious cover (IC). This will examine a pre-
development condition, the current built state, a scenario with MS4 requirements, next-generation
Conservation Development (CD) practices, and a number of future scenarios that consider potential
climate change conditions (flooding and drought) and future buildout. Scenarios will be used to illus-
trate the effect of land use decision making at the watershed and site scale and the importance of next-
generation municipal bylaws / ordinances. Project results will demonstrate how nD/rD impacts water
quality, flooding frequency and duration, channel stability, ecohydrological function, and hydrogeo-
morphology.
Next-generation CD practices will include a de-emphasis of impervious cover (IC) (e.g., primarily
access roads, driveways, parking lots and hardened or bare rooftops), and increased reliance on prac-
tices that emphasize next-generation site design and development practices (e.g., soil management
practices), architecture (e.g., green roofs, Low Impact Development (LID)) and landscape architecture
- in general, CD practices that promote conservation of site-scale functional attributes and ecosystem
services to help ensure preservation of pre-development-like hydrology, hydrogeology, and ecological
diversity and vitality. In addition, it is envisioned that such CD practices will incorporate agriculture
to increase sustainability of food systems and foster an increased appreciation and use of forest canopy
and landscape architecture to promote evapotranspiration to offset the "heat island effect" that results
from excessive IC.
The project includes the development of technical support documents and a webinar for the Southeast
New England Program (SNEP) Technical Assistance Network (TAN) to facilitate transfer of the pro-
ject outputs. The project develops a municipal engagement 'toolbox' of next-generation SW manage-
ment and CD practices that include:
1. Conceptual Site-Development Plans representing a range of hypothetical new and redevel-
opment projects that are representative of realistic MA development projects for illustrating
site management scenarios including "business as usual" (i.e., conventional) site design
practices and CD practices.
2. Next-Generation Model Ordinance and Bylaw recommendations addressing local govern-
ment requirements for SW management and site-development practices that incorporate
the findings of FDC1 Project and concurrent FDC2A work. This includes the development
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FDC Phase 2, Task Order 2B: Next Generation Watershed
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of a Watershed Protection Standard for the Development to maintain predevelopment hy-
drology and nutrient load, and resilient landscapes.
3. A Compendium of Advanced SW Management and Conservation-Based Site-Scale Design
practices to primarily inform local municipal government officials and decision makers,
and secondarily, site-development practitioners (architects, site engineers, landscape archi-
tects).
4. Communications Materials that demonstrate the impacts at the watershed and site-scale
levels to inform local land use regulatory decision making, and that are tailored to the needs
of the municipal governments.
1.1. Project Team
The Project Team lead by the Great Lakes Environmental Center (GLEC) Team has decades of ex-
perience working with EPA to successfully manage projects of all sizes and scopes. Mick DeGraeve
will serve as the Program Manager, Robert Roseen will serve as Project Manager, and Khalid Alvi,
will serve as the Project Advisor. All will stay in contact with EPA and will ensure the team adheres
to all schedules and provides high-quality deliverables. The following highlights our approach to com-
pleting the subtasks identified in the workplan.
The Project Team was a collaboration of three specialty water resources and environmental consulting
firms - Great Lakes Environmental Center, Waterstone Engineering (Waterstone), and Paradigm.
The combined expertise in watershed and nutrient control planning, stormwater management and
design, and community outreach and education provided an exceptionally qualified and capable team
with a successful track record of similar accomplishments.
Municipal Project Partners and Collaborators involved municipal planning staff and experts from
within the Taunton River Watershed.
Municipal Project Partners included:
Tricia Cassidy, Middleboro
Katelyn Gonyer, Mansfield
Jenn Carlino, Easton
John Thomas, Norton
Project Collaborators included:
Sara Burns, Ducks Unlimited (Remote)
Danica Belknap, SRPEDD
Kimberly Groff, SNEP
Scott Horsley, Consultant, Tufts University
Project member bios are listed below.
Ray Cody, Senior Policy Analyst, Water Division, EPA Region 1
Ray Cody, Ray is a senior policy analyst in the USEPA Region l's Office of Ecosystem Protection's
Surface Water Branch. Since 2009, his work has focused on stormwater implementation with an em-
phasis on impervious cover disconnection, green infrastructure stormwater control measures (SCM)
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for nutrient pollution (i.e., nitrogen and phosphorus) and approaches for control of volumetric storm-
water discharges (i.e., flooding). Prior to his work under the Clean Water Act, Ray spent 20+ years in
EPA's remedial programs and as a consultant for Fortune 100 and 500 companies. Ray has a Bachelor
of Science (B.S.), a Master's in Business Administration (M.B.A.) and a Juris Doctorate (J.D.).
Mark Voorhees, Environmental Engineer, Water Division, EPA Region 1
Mark Voorhees is an environmental engineer in the stormwater permitting program at the U.S. EPA
in New England. Currently, Mark focuses on developing information/tools to assist permittees in
building technical program capacity for implementing technically sound and economically viable
stormwater management programs to restore stormwater impaired surface waters. At EPA, he
has worked extensively in the TMDL and the Stormwater permitting programs involved with con-
ducting water quality modeling, watershed management analyses and developing representative re-
duction credits for a variety of stormwater control measures. Prior to EPA, he worked in the private
sector as a Professional Engineer conducting environmental modeling studies and developing abate-
ment plans to address combined sewer overflows and urban stormwater discharges.
Michelle Vuto, Stormwater Permits Section, Water Division, EPA Region 1
Michelle Vuto is an Environmental Scientist in the Stormwater and Construction Permits Section at
EPA R1. She serves as a permit writer for MS4s, provides technical assistance related to MS4 imple-
mentation, and manages the Construction General Permit in MA and NH.
Khalid Alvi, Water Resources Engineer, Paradigm Environmental
Alvi is a water resources engineer with extensive experience in the development of linked watershed
and stormwater BMP modeling systems. He leads teams of computer programmers and watershed
modelers to produce applications and software for federal, state, and municipal agencies. Alvi has
authored foundational software for stormwater and watershed modeling. Alvi's leadership and inno-
vative problem-solving are an asset across all phases of our modeling workflow, including problem
formulation and simplification of computational complexities. He is a registered Professional Engi-
neer in the state of Virginia.
RobertRoseen, PHD., D.WRE, PE
Dr. Roseen is the Principal and Founder of Waterstone Engineering. Dr. Roseen provides over 30
years of experience in water resources investigations. Rob is a recognized industry leader in green
infrastructure, watershed management, and nutrient control planning and the recipient of Environ-
mental Merit Awards by the US Environmental Protection Agency Region 1 in 2010, 2016, and 2019.
He consults nationally and locally on stormwater management and planning and directed the Univer-
sity of New Hampshire Stormwater Center for 10 years. Rob is deeply versed in the practice, policy,
and planning of stormwater management. He is a licensed professional engineer in NH, MA, and ME.
Julie LaBranche, JVL Planning
Julie LaBranche has worked as a private consultant in New Hampshire since 2021 engaging in projects
including Master Planning, Open Space Planning, planning technical services to Planning Boards and
Zoning Boards of Adjustment, and technical services for EPA MS4 Stormwater Permit compliance.
Previously, she served as a senior planner with the Rockingham Planning Commission from 2009-
2021 and a regional Planner with the Strafford Regional Planning Commission from 2007-2009.
LaBranche is a member of the NH Coastal Adaptation Workgroup and former NH Representative
and Vice President of the Northern New England Chapter of the American Planning Association. Her
previous employment includes city planning, natural resource management with the Maryland De-
partment of the Environment and planner for the Maryland Chesapeake Bay Critical Area Commis-
sion. She holds a B.S. in Geological Sciences from Salem state University and a M.S in Earth Sci-
ences/Geology from Montana State University.
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1.2. Funding Statement
This project has been financed with federal funds from the Environmental Protection Agency Region
1 (EPA-R1) through the Southern New England Program (SNEP) under a project titled FDC Phase
2, Task Order B: Next-Generation Watershed Management Practices for Conservation Development,
Blanket Purchase Agreement: BPA-68HE0118A0001-0003, Requisition Number: PR-R1-21-00225,
Order: 68HE0122F0003.
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FDC Phase 2, Task Order B: Next-Generation Watershed
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2. MUNICIPAL ENGAGEMENT PROCESS
The Team conducted a Municipal Engagement Process primarily through a series of working meetings
working directly with municipal partners to share key project interim results, gain local input and
support interim decision making. This engagement process fostered collaboration among the Project
and Municipal Teams to translate and share information amongst FDC1, FDC2A, and FDC2B. This
was to ensure project deliverables are developed in a manner that reflects input and perspectives of the
municipal partners and the overall communication objectives of the project. Municipal Engagement
working meetings were strategically planned and scheduled to take advantage of the technical discus-
sions for the FDC2A project so that interpretation of continuous simulation hydrologic modeling and
FDC results relating to ecosystem elements and/or conservation development stormwater control
measures shall be used to inform the development and evaluation of local site-development regulatory
options, as well as effective communication and outreach strategies to support sound decision making
on land use and site-development activities at the local government level.
2.1. Municipal Engagement Working Meetings
The Team conducted 3 Municipal Engagement Working Meetings with the Municipal Partners and
Project Team. This included the following meetings.
1. Municipal Meeting #1 -December 18, 2021 (See Appendix A). This included project introduc-
tion, background information on FDC1 and 2A and the role of 2B. It included the discussion of
the municipal toolbox elements and site development concepts.
2. Municipal Meeting #2 - June 30, 2022 (See Appendix B). The goal of this meeting was to review
progress on the municipal engagement toolbox and specific examples and work products. The
project will evaluate a range of new and redevelopment approaches to better understand and
communicate the future impact upon watersheds and the potential for enhanced site design and
management for optimal sustainability and resilience. Project partners provided input on the
development of municipal engagement outreach materials to ensure the materials effectively
address a municipal audience of land use practitioners. The intended audience is local municipal
government officials and decision makers, and secondarily, site-development practitioners (ar-
chitects, site engineers, landscape architects). This meeting was graciously held and hosted at
the Public Safety Building in Mansfield.
3. Municipal Meeting # 3- September 13, 2022 (See Appendix C). The goal of this meeting was to
discuss the last stages of the project including the concept development plans for costing and
performance, bylaw review, and outreach materials, etc. This meeting was graciously held and
hosted at the Public Safety Building in Mansfield.
2.2. SNEP Webinar
The Project Team prepared a webinar to present the FDC2B study results and findings (See Appendix
D). The webinar was targeted for the Municipal Partners to convey the critical information about
Concept Plans, Next Generation Municipal Bylaws, and Enhanced Stormwater Management and
Conservation Development Design Standards. This included a balance of artistic graphics, technical
design information, watershed health data, BMP performance, costing, and maintenance.
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FDC Phase 2, Task Order 2B: Next Generation Watershed
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3. CONCEPT DEVELOPMENT PLANS FOR HYPOTHETICAL NEW AND
REDEVELOPMENT PROJECTS
Under the directives of Task 4 of the FDC2, hypothetical real-world site-development plans were pro-
duced and subsequently employed in concept for modeling simulations and for demonstrating alter-
native site development designs and levels of potential local regulatory control for addressing water
resource and watershed health impacts (hereafter referred to as "Concept Development Plans"). The
Project Team has extensive experience in developing both concept plans in graphic form for use as an
outreach product, as well as construction level designs. In both cases the Project Team has deep ex-
pertise in design and science-translation. Of equal importance is the Teams' knowledge of feasible and
buildable designs based on decades of BMP construction experience. EPA's expectation was for the
Contractor to derive these initial Concept Development Plans from either (a) actual completed pro-
jects (having as-built design plans (or equivalent)) that the Contractor may have completed itself or (b)
from completed projects that may be available from one or more municipalities (e.g., Appendix C of
workplan). EPA is sensitive to projects that may be identifiable as sourced from one or more of the
Taunton municipalities. As such, EPA employed the descriptor "hypothetical." Lastly, and particu-
larly for plans that incorporate CD Practices, EPA's anticipation was that they be visually appealing,
suggesting collaboration with a graphic artist and landscape architect (note: The Boston Society of
Landscape Architects is an FCD1, and possibly also an FDC2A TSC participant). EPA envisioned
the initial Concept Development Plans would contain enough detail (e.g., approximate 25% level
plans (as compared to typical final as-built design plans)) in conveying important site information,
such as topography, location and extent of IC - and that such would be sufficient to support FDC2A
modeling simulations and subsequent plans incorporating various levels of CD Practices (as described
further below).
It is expected that the completed Concept Development Plans developed under Task 4 will serve as a
future reference to the SNEP region for illustrating alternative site-development designs for a range of
typical land use site-development activities that comply with alternative levels of local regulatory con-
trol focused on SW management and next-generation site design practices (i.e., CD Practices). The
Concept Development Plans include estimates of water resource and watershed health impacts asso-
ciated with development activities such as conversion of permeable vegetated surface to IC (i.e., IC
conversion), as well as estimates of the benefits associated with depicted CD Practices and SW con-
trols, which overall would achieve the specific level of on-site control being demonstrated and could
be required or incentivized in local bylaws. The GLEC Team will also develop planning level cost
estimates (if needed, based on a generalized cost/unit management area, e.g., cost per square or cubic
foot) of site work including SW management and GI SCMs (excluding costs for buildings) for each
Concept Development Plan further developed under this task (described below).
Municipal practitioner understanding and appreciation is a critical goal of this Project: one of the
goals of developing the Concept Development Plans is to visually compare a "business as usual" site
development approach with an approach that incorporates various levels and combinations of CD
Practices. This visual side-by-side comparison was used as the primary vehicle for demonstrating, in
a visceral manner, the imperative for municipal consideration and adoption of bylaws and policies
that de-emphasize IC and incorporate CD Practices. In brief, presented with the past/current and a
potential alternative future, the municipal practitioner will be rhetorically asked: "What future do you
envision?"
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FDC2A also used the Concept Development Plan design scenarios to inform development of subwa-
tershed modeling simulations for providing the FDC2B Contractor with estimates of overall cumula-
tive effects at a subwatershed scale (e.g., Upper Hodges Brook in the Wading River watershed). The
subwatershed modeling results were used by FDC2B to inform the Municipal Partners of the cumu-
lative outcome of applying MS4s to applicable new and redevelopment project across a watershed.
Accordingly, the Project Team developed Concept Development Plans depicting real-world conven-
tionally designed development projects that are and/or would be representative of typical new and
redevelopment projects likely to be encountered by municipalities participating in the project. Overall,
the selected Concept Development Plans capture a range of realistic new and redevelopment site-
development conditions assuming conventional development approaches (i.e., "business as usual")
that collectively represent a range of on-site percent IC, hydrologic soil types, natural vegetated areas
before and after development, and extent of soil disturbance. The Project Team developed Concept
Development Plans for two (2) hypothetical new residential development projects and one (1) hy-
pothetical commercial redevelopment project. As part of the Municipal Engagement process (Task
3), the Team sought input from the Municipal Partners on the selection of these new and redevelop-
ment concept projects. The focus involved simple, low-maintenance systems that are identified by the
TSC as feasible to implement for common new development and redevelopment applications. An
essential element of the Concept Development Plans was the development of designs that can easily
be replicated and maintained. This includes the use of readily implementable and standardized designs
that can be pulled from a shelf and do not involve substantial additional analysis or engineering. De-
signs contained relevant information about sizing, pretreatment, specifications, and estimated costs
per unit construction. Additionally, systems balanced ease of maintenance and the cost to construct
with optimal performance for recharge and water quality treatment.
The Concept Development Plans for each new/redevelopment alternative incorporated analyses at
four (4) different levels of local control, which included:
(i) A pre-development scenario.
(ii) A post-development scenario with no controls.
(iii) A post-development scenario with minimum LID per Massachusetts Department of Environ-
mental Protection (MADEP) standards (MS4 General Permit).
(iv) A post-development scenario with LID infiltration designed for water quality and peak control.
Each Concept Development Plan that incorporates a post-development scenario with minimum LID
per MADEP standards (iii above) focused on the application of SW management controls to comply
with the MA MS4 permit. Additionally, with each Concept Development Plan featuring a post-devel-
opment scenario with LID infiltration designed for water quality and peak control (iv above), the
Team considered a range of CD practices. These included non-structural BMPs, structural BMPs, and
LID planning such as reductions in on-site IC footprints (e.g., buildings and parking area) compared
to conventional site development.
The purpose of considering CD Practices with MS4 scenarios is to understand whether or to what
extent MS4 standards may be achieved via use of CD Practices. Consequently, these scenarios em-
phasized minimization of untreated IC (e.g., underground parking garages, dispersed GI like green
roofs, passive hydrologic disconnection of IC to undisturbed natural vegetated areas, parking area
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reductions, use of overflow permeable parking areas, and to include consideration of enhanced post-
construction permeable vegetated areas through soil augmentation and tree plantings). Systems bal-
ance ease of maintenance and cost to construct with optimal performance for recharge and water
quality treatment.
Municipal practitioner understanding and appreciation is a critical goal of this Project
All Concept Development Plans were designed for a target audience of engaged lay persons, municipal
volunteers, and municipal staff and incorporated an appropriate scale with sufficient user-friendly in-
formation to facilitate understanding of key design aspects and take-away messages related to alterna-
tive local control requirements. EPA envisioned the Concept Development Plans could employ ren-
dering techniques used by landscape architects. The plans provide an overall summary of quantified
impacts and potential benefits for the site (to be provided by the FDC2A team). TheProjectTeam has
extensive experience in both developing conceptual designs and working with target audiences to en-
sure an appropriate match of problems, solutions, and local community. The Project Team specified
a graphic designer to ensure Concept Development Plans are technically accurate, visually under-
standable, and capable of clearly conveying the intended information.
3.1. Concept Development Plans: Overview and Results
The GLEC team designed three, hypothetical real-world Concept Development Plans and performed
four scenario analyses under each (for a total of 12 examples) to demonstrate the efficacy of next-
generation watershed management practices. The Concept Development Plans were designed and
applied to three different development types and varying landscapes, both developed and undevel-
oped. An overview of the Concept Development Plans and scenario analyses are presented in Table
X, below.
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FDC Phase 2, Task Order B: Next-Generation Watershed
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Table 1. Summary of Concept Development Plans
3.1.1. Concept Development Plan 1
Concept Development Plan 1 is a high-density residential site within a larger residential neighborhood
that incorporates seven homes in a cul-de-sac.
Figure X, below, depicts the three alternative site designs (CD1.2, CD1.3, CD1.4) of Concept Devel-
opment Plan 1 and highlights the results of continuous simulation hydrologic modeling of each site
design compared to a pre-development site hydrology (CD 1.1).
Concept
Development
Plan
Development
Type
Land Use
Type
Scenario Analyses
Stormwater Management
Practices
CD 1.1: Pre-development
N/A
New
Development
High Den-
CD1.2: No controls
None
1
sity Resi-
dential
CD1.3: Minimum LID
(per MADEP)
GI and CD practices
CD 1.4: LID infiltration
for water quality and
peak control
GI and CD practices
CD2.1: Pre-development
N/A
Redevelop-
ment
High Den-
sity Com-
mercial
CD2.2: No controls
None
2
CD2.3: Minimum LID
(per MADEP)
GI and CD practices
CD2.4: LID infiltration
for water quality and
peak control
GI and CD practices
CD3.1: Pre-development
N/A
New
Development
Low Den-
CD3.2: No controls
None
3
sity Resi-
dential
CD3.3: Minimum LID
(per MADEP)
GI and CD practices
CD3.4: LID infiltration
for water quality and
peak control
GI and CD practices
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Figure 1. Concept Development Plan 1 (CD1) for High Density Residential under 3 Scenario; No Controls, Min-
imum LID, LID for Watershed Protection Standard
H
~ a
CD1.2 No Controls High Density Residential
NO CONTROL
X STD 2-PEAK FLOW CONTROL
X STD 3-GROUNDWATER RECHARGE VOLUME
X STD 4 - TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
Infiltration Trendi
CD1.3 LID MADEP High Density Residential
LID MADEP
~ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4-TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
CD1.4 LID Peak High Density Residential
LID VOLUME
/ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4-TSS 80% REMOVAL (90% MS4)
-TP60% REMOVAL
/ NO INCREASE IN NUTRIENT LOAD
/ PREDEVELOPMENT HYDROLOGY
/ RESILIENT HYDROLOGY
3.1.1.1. Site Design CD 1.2
CDl ,2 (no controls) assumes no BMPs which is common for projects that don't trigger state or federal
requirements, including municipalities with weak storm water management regulations.
Figure 2. Concept Development CD1.2 No Controls for High Density Residential
i JBi If ^
¦¦ I igl
;-*-i i'¦> ^
. ~
3.1.1.2. Site Design CD 1.3
CDl .3 (LID MADEP) was designed with minimal LID use consistent with MADEP standards for
the MS4 General Permit and incorporated three BMP types:
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19.2022
Rain gardens (driveways)
Subsurface infiltration trenches (rooftops)
Detention pond (roadways)
The rain gardens and subsurface infiltration trenches for CD 1.3 were designed with 0.5" WQV to
satisfy MADEP standards 3 (GRV) and 4 (nitrogen and phosphorous). The detention pond was de-
signed to satisfy MADEP standard 2 (Q-peak). Additionally, to include enough space for the detention
pond, it was necessary to remove one house from the site design.
Figure 3. Concept Development CD1.3 MADEP LID for High Density Residential
CD1.3 LID MADEP High Density Residential
Typical House Lot
Drainage Layout
LID MADEP
STD 2 - PEAK FLOW CONTROL
STD 3 - GROUNDWATER RECHARGE VOLUME
STD 4 -TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
NO INCREASE IN NUTRIENT LOAD
PREDEVELOPMENT HYDROLOGY
RESILIENT HYDROLOGY
Rooftop Downspout
and Infiltration Trench
Detention Pond
3.1.1.3. Site Design CD 1.4
CD1.4 (LID Peak) was designed with two BMP types;
Subsurface infiltration trenches (rooftops)
Roadway subsurface infiltration systems (driveways and roadways)
The subsurface infiltration trenches were designed with 1" WQV to satisfy MADEP standards 3
(GRV) and 4 (nitrogen and phosphorous). The roadway infiltration trenches were designed to satisfy
MADEP standard 2 (Q-peak).
15
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19.2022
Figure 4. Concept Development CD1.4 LID to Achieve the Watershed Protection Standard for High Density
Residential
CD1.4 LID Peak High Density Residential
LID VOLUME
/ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4 -TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
/ NO INCREASE IN NUTRIENT LOAD
/ PREDEVELOPMENT HYDROLOGY
/ RESILIENT HYDROLOGY
Roadway Subsurface Infiltration
and Pretreatment System
i©*J
!¦ i.H8h
Typical House Lot J1
Drainage Layout
J
r
y
Downspout and
¦ 1
The simulation results for CD1.2, CDl.3, and GDI .4 are shown in the following figures.
Figure 5: Water Quality Performance and Costing for CD1.3 Minimum LID and CD1.4 LID to Achieve the WPS
for High Density Residential
.>
¦Q
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
1.59
1.43
~ $1,365.20
$1,524.43
0.16
0.16
¦
0.05
0.01
Pre-Development Developed
Condition Condition - No
Controls
LIDMassDEP Pre-Development Developed
Condition Condition - No
Controls
LID Peak
$1,800
$1,600
$1,400
$1,200 £
$1,000 £
$800 5.
$600 ^
$400
$200
$0
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19.2022
Figure 6: Runoff Duration Curves for CD1.3 Minimum LID and CD1.4 LID for High Density Residential
Post-Dev, no BMPs LID VOLUME LID MADEP Pre-Dev
0.001
0.0001
S.O s.o \p \p \o vp \0 \o \p \p
OX o\ ON ON OS (J\ ON ON ox ON
inOLOOLnOLnouno
m-^^LnLnijDtDr^r^oo
Flow-Exceedance Percentiles (Wet Days Only)
Figure 7: Climate Resiliency Performance for CD1.3 Minimum LID and CD1.4 LID for High Density Residential
CD1.3 LID MADEP High Density Residential
0.0
£
0.2
c
jr
0.4
a
c
0.6
cc
0.8
1.0
0.7
0.6
0.5
3T
3=
0.4
o
c
3
cc
0.3
I'l
fl
r
1'
*
¦ Rainfall (in./hr)
Selected 24-hours
Post-Dev, no BMPs
Post-Dev, with BMPs
Pre-Dev
2% INCREASE
CD1.4 LID Peak High Density Residential
H
r
mr '
1
F
¦ Rainfall (in./hr)
140% INCREASE
17
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19.2022
3.1.2. Concept Development Plan 2
Concept Development Plan 2 is a high-density commercial redevelopment that includes both
residential and retail uses.
Figure X, below, depicts the three alternative site designs (CD2.2, CD2.3, CD2.4) for Concept Devel-
opment Plan 2 and highlights the results of continuous simulation hydrologic modeling of each site
design compared to a pre-development site hydrology (CD2.1).
Figure 8. Concept Development Plan 2 (CD) for Commercial Redevelopment Residential under 3 Scenario: No
Controls, Minimum LID, LID for Watershed Protection Standard
CD2.2 No Controls Commercial Redevelopment
NO CONTROL
X STD 2 -PEAK FLOW CONTROL
X STD 3-GROUNDWATER RECHARGE VOLUME
X STD 4 - TSS 80% REMOVAL (90% MS4}
-TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
CD2.3 LID Basic Commercial Redevelopment
LIDMADEP
/ STD 2-PEAK FLOW CONTROL
/ STD 3 -GROUNDWATER RECHARGE VOLUME
/ STD 4-TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
CD2.4 LID Volume Commercial Redevelopment
LID VOLUME
/ STD 2-PEAK FLOW CONTROL
~ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4-TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
/ NO INCREASE IN NUTRIENT LOAD
/ PREDEVELOPMENT HYDROLOGY
/ RESILIENT HYDROLOGY
3.1.2.1. Site Design CD2.2
CD2.2 (no controls) assumes no BMPs which is common for commercial projects that don't trigger
state or federal requirements. Site Design CD2.2 is also consistent with municipal jurisdictions with
weak stormwater management regulations.
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19.2022
Figure 9. Concept Development CD2.2 No Controls for Commercial Redevelopment
3.1.2.2. Site Design CD2.3
CD2.3 (LID MADEP) incorporates minimal LID designs consistent with MADEP standards for the
MS4 General Permit. The range of BMP types for CD2.3 include:
Drip edge infiltration (rooftop)
Permeable patio and subsurface infiltration (rooftop)
Subsurface detention system (parking lot)
The drip edge infiltration and permeable patio and subsurface infiltration with CD2.3 both incorporate
0.5" WQV and were designed to satisfy MADEP standards 3 (GRV) and 4 (nitrogen and phospho-
rous). The subsurface detention system was designed to satisfy MADEP standard 2 (Q-peak).
19
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19.2022
Figure 10. Concept Development CD2.3 MADEP LID for Commercial Redevelopment
CD2.3 LID Basic Commercial Redevelopment
LID MADEP
/ STD 2-PEAK FLOW CONTROL
/ STD 3 - GROUNDWATER RECHARGE VOLUME
/ STD 4 - TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
Subsurface Detention
Rooftop Downspout and Permeable Pavers
Drip Edge Infiltration
Trench and Walkway
Foundation
3.1.2.3. Site Design CD2.4
CD2.4 (LID Volume) was designed with four BMP types:
Drip edge infiltration (rooftop)
Permeable patio and subsurface infiltration (rooftop)
Porous asphalt pavement (parking lot)
Dry well (pervious surface run off and redundancy)
The subsurface infiltration trenches were designed with 1" WQV to satisfy MADEP standards 3
(GRV) and 4 (nitrogen and phosphorous). The roadway infiltration trenches were designed to satisfy
MADEP standard 2 (Q-peak).
The drip edge infiltration and permeable patio and subsurface infiltration were both designed with
0.5" WQV and satisfy MADEP standards 3 (GRV) and 4 (nitrogen and phosphorous). The porous
pavement satisfies M ADEP standard 2 (Q-peak).
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19.2022
Figure 11. Concept Development CD2.4 LID to Achieve the Watershed Protection Standard for Commercial
Redevelopment
CD2.4 LID Volume Commercial Redevelopment
Standard Precast
porous Asphjii Concrete Drywall
LID VOLUME
/ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGEVOLUME
/ STD 4-TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
/ NO INCREASE IN NUTRIENT LOAD
/ PREDEVELOPMENT HYDROLOGY
/ RESILIENT HYDROLOGY
Rooftop Downspout and Permeable Pavers
Drip Edge Infiltration
Trench and Walkway
Typical Porous
Pavement Detail
The simulation results for CD2.2, CD2.3, and CD2.4 are shown in the following figures.
Figure 12: Water Quality Performance and Costing for CD2.3 Minimum LID and CD2.4 LID to Achieve the WPS
for Commercial Redevelopment
CD2.2 No Controls Commercial Redevelopment CD2.3 LID Basic Commercial Redevelopment CD2.4 LID Volume Commercial Redevelopment
/
STD 2 - PEAK FLOW CONTROL
~
STD 2 - PEAK FLOW CONTROL
~
STD 2 - PEAK FLOW CONTROL
/
STD 3 GROUNDWATER RECHARGE VOLUME
/
STD 3 - GROUNDWATER RECHARGEVOLUME
/
STD 3 - GROUNDWATER RECHARGE VOLUME
X
STD 4 - TSS 80% REMOVAL (90% MS4)
~
STD 4 - TSS 80% REMOVAL (90% MS4)
/
STD 4 - TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
-TP 60% REMOVAL
-TP 60% REMOVAL
X
NO INCREASE IN NUTRIENT LOAD
X
NO INCREASE IN NUTRIENT LOAD
/
NO INCREASE IN NUTRIENT LOAD
X
PREDEVELOPMENT HYDROLOGY
X
PREDEVELOPMENT HYDROLOGY
/
PREDEVELOPMENT HYDROLOGY
X
RESILIENT HYDROLOGY
X
RESILIENT HYDROLOGY
/
RESILIENT HYDROLOGY
0.900
0.800
0.700
0.600
>¦
.a
0500
Q.
H
0.400
0.300
0.200
0.100
0.000
CD 2 - High Density Commercial (HSG-A)
0.83 0.83
$4,336
0.34
$2,290
0.015
0.015
0.005
$5,000
$4,500
$4,000
$3,500 £
$3,000 g;
$2,500 ^
v>
$2,000
w
$1,500 S
$1,000
$500
$0
Pre-Development Developed Condition LID MassDEP Pre-Development Developed Condition
Condition - No Controls Condition before BMPs
21
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19.2022
Figure 13: Runoff Duration Curves for CD2.3 Minimum LID and CD2.4 LID for Commercial Redevelopment
Post-Dev, no BMPs LID VOLUME LID MADEP Pre-Dev
i.OOOl
Sp Np SO
on on on
O LO o
sp sp
ON ON on
o lo o in
rM r»j ro m
sp sp vp
0s- ON on
O LH O LH O LO
"sj" LO LD |r' - - " ' "T
0.2 ' P
0.6
0.8
1.0
1.0
0.
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
!
¦ Rainfall (in./hr)
Selected 24-hours
^Post-Dev, no BMPs
Post-Dev, with BMPs
're-L»ev
NO INCREASE
\
J
K h.
»
ID
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19.2022
3.1.3. Concept Development Plan 3
Concept Development Plan 3 is a low-density residential site incorporating five homes with a lake
bordering the site to the north.
Figure X, below, depicts the three alternative site designs (CD3.2, CDS.3, CD3.4) corresponding to
Concept Development Plan 3 and includes the results of continuous simulation hydrologic modeling
of each site design compared to a pre-development site hydrology (CD3.1).
Figure 15. Concept Development Plan 3 (CD3) for Low Density Residential under 3 Scenario: No Controls,
Minimum LID, LID for Watershed Protection Standard
CD3.2 No Controls
Low Density Residential
NO CONTROL
X STD2- PEAK FLOW CONTROL
X STD 3 - GROUNDWATER RECHARGE VOLUME
X STD 4 - TSS 80% REMOVAL (90% MS4)
-TP60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
CD3.3 LID MADEP
Low Density Residential
UD MAOEP
/ STD 2-PEAK FLOW CONTROL
/ STD 3 - GROUNDWATER RECHARGE VOLUME
/ STD 4 - TSS 80% REMOVAL (90% MS4I
TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
CD3.4 LID Peak
Low Density Residential
LID VOLUME
/ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4 -TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
/ NO INCREASE IN NUTRIENT LOAD
/ PREDEVELOPMENT HYDROLOGY
/ RESILIENT HYDROLOGY
3.1.3.1 Site Design CD3.2
CD3.2 (no controls) assumes no BMPs which is common for projects that don't trigger state or federal
requirements, including municipalities with weak stormwater management regulations.
23
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19.2022
3.1.3.2. Site Design CD3.3
CD3.3 (LID MADEP) was designed with minimal LID use that is consistent with MADEP standards
for the MS4 General Permit and incorporated the following BMPs:
Forested buffers as qualifying pervious areas for lakeshore properties (ESSD credit #7)
Meadow buffers as qualifying pervious areas for residential house lots (ESSD credit #3)
Meadow buffers as qualifying pervious areas for residential roadways (ESSD credit #4)
The forested buffers earn ESSD credit 7 and the meadow buffers achieve ESSD credits 3 and 4. Cu-
mulatively, the ESSD credits address MADEP standards 2 (peak), 3 (GRV), and 4 (TSS/TP).
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19.2022
Figure 17. Concept Development CD3.3 MADEP LID for Low Density Residential
CD3.3 LID MADEP
Low Density Residential
LID MADEP
~ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4-TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
A NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
3.1.3.3. Site Design CD3.4
CDS .4 (LID Peak) was designed with the following BMP types:
Forested buffers as qualifying pervious areas for lakeshore properties (ESSD credit#7)
Meadow buffers as qualifying pervious areas for residential house lots (ESSD credit#3)
Meadow buffers as qualifying pervious areas for residential roadways (ESSD credit#4)
Drip edge infiltration (rooftop)
Roadway infiltration trench
Similar to CD3.3, CDS.4 incorporates forested buffers to earn ESSD credit 7 with the meadow buffers
achieving ESSD credits 3 and 4. Cumulatively, the ESSD credits address MADEP standards 2 (peak),
3 (GRV), and 4 (TSS/TP). Both the drip edge infiltration and the roadway infiltration trench were
designed with 1" WQV.
Roadway Buffer and Infiltration
Residential Forested Meadow Buffer
Roadway
Meadow Buffer
of80+ft
25
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19.2022
Figure 18. Concept Development CD3.4 LID to Achieve the Watershed Protection Standard for Low Density
Residential
CD3.4 LID Peak
Low Density Residential
LIDVOLUME
/ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4 - TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
/ NO INCREASE IN NUTRIENT LOAD
~ PREDEVELOPMENT HYDROLOGY
/ RESILIENT HYDROLOGY
Infiltration
The simulation results for CD3.2, CD3.3, and CD3.4 are shown in the following figures.
Figure 19: Water Quality Performance and Costing for CD3.3 Minimum LID and CD3.4 LID to Achieve the WPS
for Low Density Residential
CD3.2 No Controls
Low Density Residential
NO CONTROL
X STD 2-PEAK FLOW CONTROL
X STD 3 - GROUNDWATER RECHARGE VOLUME
X STD 4-TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
CD3.3 LIDMADEP
Low Density Residential
LIDMADEP
/ STD 2-PEAK FLOW CONTROL
/ STD 3-GROUNDWATER RECHARGE VOLUME
/ STD 4-TSS 80% REMOVAL £90% MS4)
-TP 60% REMOVAL
X NO INCREASE IN NUTRIENT LOAD
X PREDEVELOPMENT HYDROLOGY
X RESILIENT HYDROLOGY
CD3.4 LID Peak
Low Density Residential
LIDVOLUME
/ STD 2-PEAK FLOW CONTROL
/ STD 3 -GROUNDWATER RECHARGE VOLUME
/ STD 4-TSS 80% REMOVAL (90% MS4)
-TP 60% REMOVAL
/ NO INCREASE IN NUTRIENT LOAD
/ PREDEVELOPMENT HYDROLOGY
/ RESILIENT HYDROLOGY
0.92
0.16 0.12
Pre-Development Condition Developed Condition - No LIDMassDEP LID Peak
Controls
Drip Edge
Infiltration Trench
Roadway Buffer and Infiltration
Residential Forested Meadow Buffer
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19. 2022
Figure 20: Climate Resiliency Performance for CDS.3 Minimum LID and CD3.4 LID for Low Density Residential
CD3.3 LID MADEP
0.4
0.6
0.8
1.0
3.0
2.5
2.0
1.0
0.5
rr '
!
1
1
1
1
¦ Rainfall (in./hr)
Selected 24-hours
Post-Dev, no BMPs
70% INCREASE
J
5ost-Dev, with BMPs
>re-Dev
7
i
K A.
n
M
$ s
§ 8
S S
CD3.4 LID Peak
o.o
0.2
0.4
0.6
0.8
1.0
3.0
2.5
2.0
1.5
r'F
1
"*r '
¦ Rainfall (in./hr)
NO INCREASE
hJL
Selected 24-hours
Post-Dev, no BMPs
Post-Dev, with BMPs
Pre-Dev
8 8
8 8
8 8 S
CsJ CM ^
«-t cm rri
8 8 I
27
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19, 2022
4. MUNICIPAL REGULATORY AUDITS, REVIEW, AND RECOMMENDATIONS
4.1. Local Bylaw Review
The purpose of this task was to provide a review of local by-laws and regulations, an audit frame-
work based on the MA Audubon Regulatory Audit Tool, and recommendations to improve imple-
mentation of stormwater management and water quality protections at the local level.
Additionally, this will identify and proposed alternative local regulatory control requirements (i.e.,
bylaws, regulations municipal operation procedures and policies) focused on site design and develop-
ment practices and on-site stormwater management for new and redevelopment projects that may
impact or protect watershed health and function. Municipalities may consider adopting specific regu-
latory provisions that meet the goals of the community such as those detailed in the town's Master
Plan, conservation-based plans, Hazard Mitigation Plan, and operational plans.
This includes local regulatory approaches along with examples, discussion of how, why or to what
extent such provisions are currently employed or may be best implemented. Additionally, it is im-
portant to identify those sets of State and federal regulations that most directly control the local-regu-
latory elements of site-development activities and stormwater management. Finally, this task will
highlight preliminary potential areas for improvements to local regulations, provide recommendations
for how best to implement updates based on review of existing model regulatory language that could
used as part of bylaw updates.
4.2. MA Audubon - Municipal Zoning By-Laws, Subdivision and Site Plan Review Reg-
ulations, and Stormwater Audit Tool And Overview
The review was conducted based on an adaptation of the Massachusetts Audubon Bylaw Review for
LID & Climate-Smart, Nature-Based Solutions1. The review adapted the bylaw audit tool which is
organized around 5 goals. The regulatory audit tool can be customized to the users' needs and can
produce a generalized snapshot of how a community regulates stormwater, water quality, environ-
ment and natural resources. The 5 goals are described below.
Goal 1: Protect Natural Resources and Open Space
The focus of this section is to limit clearing and grading and encourage soil management, the use of
native species, and revegetation of disturbed areas. Often, communities have language such as "due
regard shall be shown for natural features" without any specific limitations or guidelines that can be
used by local boards to ensure developers are following the true intent of the community. The retention
of natural vegetation and soils is the single most efficient means of reducing development impacts on
water resources, avoiding costs associated with piping and other "grey" stormwater management fea-
tures as well as the need for irrigation. There are also many other benefits including habitat for
birds and pollinators, trees for shade and clean air. and protection of natural scenery that contributes
to property values and a high quality of life.
1 Massachusetts Audubon Bylaw Review for LID & Climate-Smart, Nature-Based Solutions
https://www.massaudubon.org/our-conservation-work/policv-advocacv/shaping-climate-resilient-communi-
ties/publications-communitv-resources/bvlaw-review
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19, 2022
Goal 2: Promote Efficient Compact Development Patterns and Infill
Often, making dimensional requirements such as setbacks, lot size, and frontage more flexible as well
as allowing common drives will help allow the community to encourage efficient, compact designs.
These help to decrease impervious surfaces and increase infiltration, while still supporting new devel-
opment.
Goal 3: Smart Designs that Reduce Overall Imperviousness
This section reviews site design such as street location, road width, cul-de-sac design, curbing, roadside
swales, and sidewalk design and location. There are many opportunities for communities to minimize
impervious surfaces and allow for infiltration through curb cuts, swales, and cul-de-sacs with biore-
tention, among other things.
Goal 4: Adopt Green Infrastructure Stormwater Management Provisions
This section looks to explicitly discuss LID as a preferred method, such as requiring roof runoff to be
directed into vegetated areas, and a preference for infiltration wherever soils allow or can be amended.
Bylaws and/or regulations should clearly specify what LID is and which BMPs are preferred or re-
quired. Communities should also require an operations and maintenance plan to encourage effective
use of LID methods. Adopting a specific LID bylaw can help clearly define and incorporate LID as a
preferential stormwater management technique. Defining LID within this bylaw also decreases the
need to explain LID throughout each of the Zoning bylaws. SPR. and subdivision rules and regula-
tions and reduce the potential for any conflict between regulations and bylaws. This section also in-
cludes additional stormwater management considerations relevant to the MS4 permit.
Goal 5: Encourage Efficient Parking
Parking accounts for a large amount of impervious surface within new and redevelopment projects
and offers an enormous opportunity for using LID. By reducing the amount of required parking - or
even including parking maximums instead of minimums. communities can drastically reduce their
impervious surfaces and runoff. Many communities already require landscaping in parking areas,
which also offers an opportunity to allow curb cuts and infiltration in these areas - improving water
quality and reducing the need for irrigation.
Visit www.mass.gov/guides/municipal-compliance-fact-sheet-stormwater for more informational re-
sources.
29
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19, 2022
4.3. Regulatory Audit Profiles - Easton, Mansfield, Middleborough
A review was completed of municipal by-laws and land development regulations relating to storm-
water management and water quality standards. Below is a summary of findings from the review of 3
towns.
Findings of Topics Not Addressed
Recommendations)
Municipalities rely heavily on references to the
MA DEP Stormwater Handbook 2and Standards
for the majority of their stormwater management
requirements
Suggest addition of a brief summary of the ma-
jor elements of the MA DEP Stormwater Hand-
book along with definitions of key terms. Sug-
gest annual refresher training on MA DEP
Stormwater Handbook and Standards for the
Planning Board and Conservation Commis-
sion.
Low Impact Development is rarely if at all men-
tioned or defined
Include a paragraph or two with a definition to
alert Board members and applicants to the ben-
efits of an LID approach.
Climate Change impacts such as current extreme
and future increased precipitation
Include a paragraph or two with a definition to
alert Board members and applicants to the ben-
efits of applying new precipitation data and fu-
ture projections in the siting and design of
stormwater infrastructure.
Private roads and their stormwater infrastructure
maintenance and inspection is not addressed
For the purposes of public health and safety and
access for emergency services, stormwater in-
frastructure should have an Operations and
Maintenance Plan in place and annual or semi-
annual inspections conducted.
Erosion and Sediment Control Plans are not men-
tioned or detailed significantly
These Plans may be required under the MA
DEP Stormwater Manuals and Standards. Pre-
construction site inspections should be com-
pleted and documented to ensure controls are
in place.
Operation and Maintenance (O&M) Agreements
are standard management procedure for storm-
water infrastructure
O&M Agreements are important to protect the
municipality and ensure stormwater infrastruc-
ture is functioning properly during construction
and post-construction. These agreements also
allow the municipality to make emergency re-
pairs if necessary.
Written procedures and for site inspections, re-
porting, follow up, and processing violations are
absent. Municipal representative(s) responsible
for coordinating activities should be identified.
This record keeping is a requirement of the EPA
MS4 Permit. Most of these documents would
reside either in the Code Enforcement or Plan-
ning Offices. Suggest a centralized system ei-
ther on paper or digitally compiled and staff
should be knowledge and access of its location.
Refer to additional audit results and resources in the attached Audit Tool-Excel spreadsheet.
2 MassDEP (2008). Massachusetts Stormwater Handbook, Massachusetts Department of Environmental Pro-
tection.
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4.3.1. Easton Regulatory Audit Results (See Appendix F for full checklist)
SWM - WQ STANDARD/REQUIREMENT
BY-LAW OR REGULA-
TION
FINDINGS
Stormwater Management Plan
Chapter 501-34-35
Plan required: Reference to MA DEP Stormwater Manuals and Stand-
ards: threshold for applicability 40,000 square feet
SWM Site Redevelopment Standards
Chapter 200, Part E
Requirements for pollutant removal and volume controls
Infiltration/Recharge Rate and Volume Req.
Reference to MA DEP Stormwater Manuals and Standards
Discharge Volume Req. for Post-Construction
Water Quality Treatment Standards (P, N, TSS)
LID - Site Planning and Design Strategies
Reference to MA DEP Stormwater Manuals and Standards
LID - Recommended Technical Manual/Design Materials
LID - Subsurface Infiltration Practices
LID - Impervious Cover Minimized
LID - Impervious Cover Maximum limit as % of parcel
LID - Capture and Reuse of Runoff on site
LID - Bio-Retention Infiltration Practices
LID -SWM Systems Distributed on Site
LID - Pervious Pavement/Materials
LID - Retention of natural cover, managed turf
Climate Change - Use current Extreme Precipitation data
No standards or references
Climate Change - Use Projected Increases in PPT
Climate Change - Upgrade existing for PPT Conditions
Construction Bond/Escrow for Review
Article X 501-48-52
Erosion and Sediment Control Plan
Not specified
Pre-Construction Site Inspection, Controls in Place
Not specified
Site Inspections During Construction
Chapter 501-41
Inspection and Control requirements
Process for Construction Site Violations
Not specified
Post Construction Site Inspection & Reporting
Chapter 501-41
Inspection and Control requirements
Process for Post-Construction Site Violations
Not specified
Operations & Maintenance Agreement - Public Roads
Chapter 501-35.B(6) O&M
Plan
Also see Chapter 501-36.A Compliance, Chapter 501-41.E.2(e) Road Ac-
ceptance
Operations & Maintenance Agreement Recorded
Not specified
Written Procedure for Site Reporting & Follow up
Chapter 501-37 Annual Re-
port
No submission date or process specified
Submission of final As-Built Plans (w/in 2 years)
Chapter 501-36.B
SWM = Stormwater Management WQ = Water Quality LID = Low Impact Development PPT = Precipitation
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4.3.2. Mansfield Regulatory Audit Results
SWM - WQ STANDARD/REQUIREMENT
BY-LAW-REGULATIONS
FINDINGS
Stormwater Management Plan
Ch. 185-15 {B6}
Conservation Commission Regulations and review apply
MA Stormwater Management Policy (MA Clean Waters Act)
[MGLC.21, sections 23-56]
SWM Site Redevelopment Standards
Reference to MA DEP Stormwater Manuals and Standards
Infiltration/Recharge Rate and Volume Req.
Discharge Volume Req. for Post-Construction
Water Quality Treatment Standards (P, N, TSS)
LID - Site Planning and Design Strategies
Reference to MA DEP Stormwater Manuals and Standards
LID - Recommended Technical Manual/Design Materials
LID - Subsurface Infiltration Practices
LID - Impervious Cover Minimized
LID - Impervious Cover Maximum limit as % of parcel
LID - Capture and Reuse of Runoff on site
LID - Bio-Retention Infiltration Practices
LID -SWM Systems Distributed on Site
LID - Pervious Pavement/Materials
LID - Retention of natural cover, managed turf
Climate Change - Use current Extreme Precipitation data
Not specified
Climate Change - Use Projected Increases in PPT
Climate Change - Upgrade existing for PPT Conditions
Construction Bond/Escrow for Review
Ch. 185-25
Surety may be required by Conservation Commission review
Erosion and Sediment Control Plan
Ch. 185-15 & 21.11
Conservation Commission Regulations apply
Pre-Construction Site Inspection, Controls in Place
Ch. 185-24
Completed by Conservation Commission
Site Inspections During Construction
Ch. 185-27
Completed by Conservation Commission
Process for Construction Site Violations
Post Construction Site Inspection & Reporting
Process for Post-Construction Site Violations
Ch. 185-23
Conservation Commission
Operations & Maintenance Agreement - SWM
Ch. 185-23
Operations & Maintenance Agreement Recorded
Not specified
Written Procedure for Site Reporting & Follow up
Not specified
Submission of final As-Built Plans (w/in 2 years)
Ch 185-26
Date/timing not specified
SWM = Stormwater Management WQ = Water Quality LID = Low Impact Development PPT = Precipitation
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4.3.3. Middleborough Regulatory Audit Results
SWM - WQ STANDARD/REQUIREMENT
BY-LAW-REGULATIONS
FINDINGS
Stormwater Management Plan
Ch. 271
Reference to MA DEP Stormwater Manuals and Standards. 5.000
square foot applicability threshold. City Engineer assigned authority to
review stormwater management plans.
SWM Site Redevelopment Standards
Reference to MA DEP Stormwater Manuals and Standards
Infiltration/Recharge Rate and Volume Req.
Discharge Volume Req. for Post-Construction
Water Quality Treatment Standards (P, N, TSS)
LID - Site Planning and Design Strategies
Reference to MA DEP Stormwater Manuals and Standards
LID - Recommended Technical Manual/Design Materials
LID - Subsurface Infiltration Practices
LID - Impervious Cover Minimized
LID - Impervious Cover Maximum limit as % of parcel
LID - Capture and Reuse of Runoff on site
LID - Bio-Retention Infiltration Practices
LID -SWM Systems Distributed on Site
LID - Pervious Pavement/Materials
LID - Retention of natural cover, managed turf
Climate Change - Use current Extreme Precipitation data
Not specified
Climate Change - Use Projected Increases in PPT
Climate Change - Upgrade existing for PPT Conditions
Construction Bond/Escrow for Review
Not specified
Erosion and Sediment Control Plan
Not specified
Pre-Construction Site Inspection, Controls in Place
Not specified
Site Inspections During Construction
Process for Construction Site Compliance/Enforcement
Ch.271-8.B,Ch. 271-11
Post Construction Site Inspection & Reporting
Not specified
Process for Post-Construction Site Violations
Ch.271-8.B, Ch. 271-11
Operations & Maintenance Agreement - Public Roads
Not specified
Operations & Maintenance Agreement Recorded
Not specified
Written Procedure for Site Reporting & Follow up
Not specified
Submission of final As-Built Plans (w/in 2 years)
Not specified
SWM = Stormwater Management WQ = Water Quality LID = Low Impact Development PPT = Precipitation
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4.4. Recommended Zoning By-Laws and Regulations Amendments for Watershed Pro-
tection
A finding of the regulatory audit process revealed several deficits in translating state and federal level
permitting requirements to implementation at the municipal level. The following observations are of-
fered to clarify how connections can be made across multiple jurisdictions.
Local By-laws and land development regulations lack connection to, follow through and
translation from state stormwater requirements to implement approved plans and applica-
tions.
By-laws and Regulations lack clear and detailed written procedures for how approved plans,
agreements and other legal documents will be implemented by municipal staff and officials,
boards and commissions, engineering reviewers, town counsel and others. Suggest a process
for transfer/access to application reports and documents to all local representatives who
need to review them.
By-laws and Regulations lack an "end point" when all conditions have been met and who
makes that determination and what is the process to finalize a municipal permit (e.g. a final
site inspection and sign off on all elements of the application).
Create organizational processes (e.g. flow charts and reporting schedules) to coordinate from
State and federal permitting to local implementation would be extremely helpful to enhance
efficiency and accuracy and to ensure stormwater management and water quality are pro-
tected.
4.4.1. Municipal Stormwater By-Law and Land Development Standards
EPA Minimum Standards for Municipal Separate Storm Sewer System (NPDES MS4) Phase II
Permits
An important component of the EPA MS4 Permit is to address and regulate redevelopment projects.
Many sites being redeveloped have either no stormwater management controls or undersized and un-
derperforming infrastructure. In many communities, redevelopment represents the largest percentage
of development applications. Existing water quality impairments result from development already on
the landscape. The best most efficient way of reversing this is to require redevelopment sites to make
stormwater management improvements as part of the development application process.
Site Redevelopment Projects
Regulatory requirements for Site Redevelopment Projects should include measurable standards for
water quality protections and/or improvements (refer to redevelopment standards in the EPA MS4
Permit section 2.3.6.e). Such standards may include reduction of site impervious cover, implementa-
tion of water quality measures such as pre-treatment and infiltration and retrofitting of existing un-
managed site runoff from rain and snow melt.
References:
MA PEP Stormwater Manuals and Standards
New Hampshire Southeast Watershed Alliance Model Stormwater Standards
Massachusetts Metropolitan Area Planning Council - Low Impact Development Toolkit
Maryland Critical Area Commission for the Chesapeake and Atlantic Coastal Bays - Stormwater
New Hampshire Southeast Watershed Alliance Model Stormwater Standards
Massachusetts Metropolitan Area Planning Council
New Hampshire Department of Environmental Services - Alteration of Terrain Bureau
New Hampshire Department of Environmental Services Volume 2 Post-Construction Best Man-
agement Practices: Selection and Design
City of Portland. Maine - Stormwater Manual
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SAMPLE LANGUAGE
Definition of Redevelopment
Redevelopment (as applicable to this stormwater regulation) means:
a. Any construction, alteration, or improvement that disturbs existing impervious area (including
demolition and removal of road/parking lot materials down to the erodible subbase) or expands
existing impervious cover by any amount, where the existing land use is commercial, industrial,
institutional, governmental, recreational, or multifamily residential.
b. Any redevelopment activity that results in improvements with no increase in impervious area shall
be considered redevelopment activity under this regulation if capital cost of improvements is
greater than 30% of the appraised property value.
c. Any new impervious area over portions of a site that are currently pervious.
The following activities are not considered redevelopment:
Interior and exterior building renovation.
Resurfacing of an existing paved surface (e.g. parking lot, walkway or roadway).
Pavement excavation and patching that is incidental to the primary project purpose, such as
replacement of a collapsed storm drain.
Landscaping installation and maintenance.
Reference: New Hampshire Southeast Watershed Alliance Model Stormwater Standards
4.4.2. Stormwater Management General Application Requirements
Municipal approval of development projects contain many complex layers of agreements, easements,
legal documents and financial agreements that require follow up actions and municipal implementa-
tion of procedures, approvals and processing. Recommendations contain administrative processes that
can help organize the post-approval process.
SAMPLE LANGUAGE
Project Engineer Certification of Intent
Project applications will include a Project Engineer Certification of Intent that certifies compliance
with the stormwater regulations as detailed below:
I certify under penalty of law that this document and all attachments were prepared under my
direction or supervision, in accordance with an approach designed to be consistent with munic-
ipal Stormwater Management Engineering Standards and to the maximum extent feasible, to
promote decentralized stormwater management systems modeled after natural hydrologic fea-
tures and infiltration practices that facilitate local groundwater recharge using Low Impact De-
velopment, and will further compliance with the {insert name of waterbody} Total Maximum
Daily Load (TMDL) and the Municipal Separate Storm Sewer System (NPDES MS4) Phase II
permit. Based on my inquiry of the person or persons who manage the system, or those persons
directly responsible for gathering the information, the information submitted is, to the best of
my knowledge and belief, true, accurate, and complete. I have no personal knowledge that the
information submitted is other than true, accurate, and complete. I am aware that there are
significant penalties for submitting false information for knowing violations. The certification
shall be stamped and dated by a professional engineer licensed in the state of Massachusetts.
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Stormwater Management Performance Enhancements
Existing stormwater management regulations, street design standards and stormwater manage-
ment design standards should: 1) be updated based on the guidance document {select a technical
guidance document relevant to the area/region} to include all projects under municipal review,
private and public sector developments, including public and capital improvements, and 2) require
a Project Engineer Certification of Intent.
SAMPLE LANGUAGE
Administrative Implementation of Approval Requirements
Stormwater Management Plan Approval and Recordation
1. Plan Approval and Review. The Planning Board shall approve the Stormwater Management Plan
if it complies with the requirements of these regulations and other requirements as provided by
law. At the discretion of the Planning Board, a technical review by a third party may be required
of any stormwater management and erosion control plan prepared under these regulations. The
technical review shall be performed by a qualified professional consultant, as determined by the
Planning Board, and the expense of which shall be the full responsibility of the applicant.
2. Recordation of Approved Stormwater Management Plan. After final Planning Board approval,
and established as a condition of such approval, the owner of record of the property shall record
at the Registry of Deeds documentation sufficient to provide notice to all persons that may acquire
any property subject to the requirements of and responsibilities described in the approved storm-
water management plan (see RSA 477:3-a). The notice shall comply with the applicable require-
ments for recording contained in RSA 477 and 478.
Operations and Maintenance Criteria
Stormwater management and sediment and erosion control plans shall be incorporated as part of any
approved site plan or subdivision plan. The owner of record of the property shall record a Notice of
Decision of these plans at the Registry of Deeds. The Notice of Decision shall be attached to the
property deed and apply to all persons that may acquire any property subject to the approved storm-
water management and sediment control plans. The Notice of Decision shall reference the require-
ments for maintenance pursuant to the stormwater management and erosion and sediment control
plans as approved by the Planning Board.
Post-Construction Stormwater Infrastructure-Inspection and Responsibility
Municipal staff or their designated agent shall have site access to complete routine inspections to en-
sure compliance with the approved stormwater management and sediment and erosion control plans.
Such inspections shall be performed at a time agreed upon with the landowner. If permission to inspect
is denied by the landowner, municipal staff or their designated agent shall secure an administrative
inspection warrant from the district or superior court under RSA 595-B Administrative Inspection
Warrants. Expenses associated with inspections shall be the responsibility of the applicant/property
owner.
The applicant shall bear final responsibility for the installation, construction, inspection, and disposi-
tion of all stormwater management and erosion control measures required by the Planning Board. Site
development shall not begin before the Stormwater Management Plan receives written approval by
the Planning Board.
The municipality retains the right, though accepts no responsibility, to repair or maintain stormwater
infrastructure if: a property is abandoned or becomes vacant; and in the event a property owner refuses
to repair infrastructure that is damaged or is not functioning properly.
Reference:
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New Hampshire Southeast Watershed Alliance Model Stormwater Standards
Creation of New Streets - Public or Private
Review and approval of street and road development plans can present different challenges depending
on the road status as private or public (municipally owned and maintained). If a development proposes
a public street or road, in both instances, that infrastructure needs to meet the municipal standards for
design and construction but also the municipalities anticipated maintenance requirements and costs
for maintenance of the infrastructure (e.g. whether the municipality require open drainage or allow
closed drainage systems).
SAMPLE LANGUAGE
If a development proposes a private street or road, the municipality should enact an Operations and
Maintenance (O&M) Agreement with the developer/landowner at the time of application approval.
This O&M agreement is critical to carrying forward any conditions of approval, site inspection sched-
ules, other site maintenance obligations, particularly in the event the property is sold, and finalizing
any financial interests such as an Escrow Account or Bond being held for property development.
If a development proposes a public street or road, an O&M Agreement should be in place until such
time the street or road is accepted by the municipality as a public way under their jurisdiction. Such
O&M Agreements can be extended for a period of 1-2 years to capture a variety of storm conditions
whereby site inspections are conducted to ensure proper functioning of the roadway and its infrastruc-
ture as approved, designed and constructed. This may include water quality testing for any EPA MS4
Permit jurisdictional outfalls, connections to the municipal storm sewer system (if applicable) and
direct discharges to surface waters.
4.4.3. EPA NPDES MS4 Permit Inspection Requirements
An important aspect of compliance with the EPA Municipal Separate Storm Sewer System (NPDES
MS4) Phase II Permit is conducting and documenting site inspections both during construction and
post-construction. Often inspections are part of a municipal approval of erosion and sediment control
plans and stormwater plans by the Planning Board, Town Engineer or Conservation Commission and
in some cases the Zoning Board.
Site Inspections During Construction
Site inspections during construction ensure proper erosion and sediment control and control of storm-
water runoff. This is often implemented through a Sediment and Erosion Control Plan that includes
stringent perimeter controls and treatment of any discharges from the development site (if any). In-
spections during critical steps in the construction sequence can prevent unintended consequences such
as infrastructure failure and improperly installed infrastructure. Results of inspections should be filed
with the municipality and any site violations forwarded to the appropriate staff or officials for pro-
cessing.
SAMPLE LANGUAGE
Site Inspections During Construction shall be based on an agreement between the developer/property
owner and the municipality. An inspection schedule will be based on a construction sequence of ac-
tivities that require inspection before construction can resume. The construction site inspection sched-
ule is highly site specific, so a template is not suitable except for the following basic elements:
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¦ Establish a sequence of construction and associated inspections. This is often part of a con-
struction cost estimate for a surety or bond however the details may change during the
course of application review and approval.
¦ Designate a municipal representative to perform site inspections. Document their contact in-
formation on the inspection agreement.
¦ Document information about the site construction manager(s) (e.g. name, address, phone
number(s), email address).
¦ Attach a complete set of approved application plans to the site inspection agreement. Include
a sign-off sheet to record when and who performed each site inspection, weather conditions,
time of day, who was present, and observation notes. Note also if site photographs were
taken and by whom and store them in a secure location with the municipality.
Post-Construction Municipal Inspections
Post-construction inspections are often part of a municipal approval and construction agreement that
may include site specific conditions be met before an occupancy permit is issued. These inspections
are intended to verify that site construction has been implemented according to the approved plans,
infrastructure is functioning as designed, and that submission of As-Built Plans will accurately reflect
site conditions. The bulleted items listed under Site Inspections During Construction apply.
Site inspections should address any conditions of the municipal approval document. A final inspection
report from the municipal inspector should be provided to the municipal approval authority (Planning
Board, Conservation Commission, Code Enforcement Officer, Building Inspector).
Regional Approaches to Site Inspections
There has been interest in recent years by municipalities to work together to create a "regional" in-
spection program for both during construction and post-construction. Below are some ideas provided
by several municipalities participating in this project.
SAMPLE GUIDANCE/LANGUAGE
Municipalities may work together to create an administrative and funding mechanism to streamline
site inspections by developing the following tools and processes:
¦ Creation of a regional inspector position to provide services and would be funded by multi-
ple communities. Funding sources may include fee at time of application, fee paid from an
escrow or bond account, or time of service fee.
¦ An example of a regional approach is being tested in Westborough, Massachusetts (uncon-
firmed)
¦ Implement a self-inspection and reporting program that requires submission of an annual in-
spection report signed by a licensed engineer.
Sources: SNEP Workshop Participants on September 19, 2022; Town of Westborough Building De-
partment
4.4.4. Water Quality and Watershed Health and Function
Municipal By-Law and Land Development Standards should include clearly identified stormwater
management, water quality protection and mitigation of existing water quality impairments for surface
waters and jurisdictional outfalls. By-Laws and Land Development Regulations should consider and
include basic provisions for landscape level conditions that influence stormwater flows and water qual-
ity:
¦ Groundwater Recharge and Drinking Water Supply Contribution Areas
¦ Factors that may impair water quality such as shallow bedrock and steep slopes
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¦ Floodplains and Areas Subject to Flooding (refer to municipal Hazard Mitigation Plan)
¦ Wetlands and Riparian Areas
¦ Wildlife and Plant Habitats
Open Space Residential Development
The goal of Open Space Residential Development (OSRD) (sometimes referred to as Conservation
Subdivision Development) is to conserve and protect valuable natural and other resources that provide
environmental benefits and tangible benefits to the health and safety of the community. OSRD ordi-
nances and regulations may include specified modifications to zoning dimensional requirements, sub-
division and site plan review requirements, and an expedited review process. OSRD applicability may
be scaled to the size of the development parcel (e.g. a minimum acreage) and requirements for open
space land conservation.
Objectives of OSRD are to:
Include resource protection as part of the land development process
Inventory site specific resources before a development plan is prepared
Implement safeguards that maintain natural processes in the post-development condition
Safeguard against flooding, erosion, damage to infrastructure and impacts to life and property
The OSRD application process often requires a preliminary consultation with the Planning Board and
the municipal technical advisory committee (if the municipality has one). The OSRD process typically
incorporates a 4-step process for site development applications:
1. Prepare an existing conditions plan that details all man-made, natural features and environ-
mentally sensitive areas on the development site
2. Prioritize areas for conservation and increased protection from development impacts by cre-
ating a "development area" that incorporates all required setbacks, buffers, including storm-
water and surface drainage, and other conditions required by the approval board
3. Prepare a draft plan showing development areas and/or subdivided lots, roads, utilities and
stormwater infrastructure
4. Finalize the development plan with feedback from approval boards and others detailing any
conditions required as part of the approval
The final development plan application should have all agreements, easements and legal documents
in place and reviewed by municipal representatives before approval and these documents should be
officially recorded to run with the land.
References:
NewburyportOSRD https://librarv.municode.com/ma/newburvport/codes/code of ordi-
nances?nodeId=APXAZOORNE SXIVOPSPREDEOS
Conservation Subdivision Hand-
book https://www.google.com/url?sa=i&rct=i&q=&esrc=s&source=web&cd=&cad=ria&uact=8
&ved=0CAMOw7AJahcKEwiO5Q7V5-
z6AhUAAAAAHOAAAAAOAw&url=https%3A%2F%2Fwww.ncufc.org%2Fuploads%2FConser-
vation subdivision.pdf&psig=AOvVaw3AlrMwxn3o4mdYRpVSGfOq&ust=1666286657378667
High Risk Land Uses
There are any number of common land uses that pose a high risk of contamination to surface water
and groundwater when exercised improperly. Even small spills and spills that occur over an extended
period undetected can lead to irreversible contamination. Prevention is far less costly than mitigation
after the fact. By prohibiting high risk uses in sensitive areas particularly those areas that serve as
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drinking water supplies public health and safety and land values are protected. Stormwater manage-
ment plays a critical role in protecting water quality on developing and developed sites. However,
strict land use controls along with stringent stormwater management standards can prevent contami-
nation.
SAMPLE GUIDANCE LANGUAGE
The table below describes the sources and impacts from common environmental pollutants. Ensuring
that adequate testing is performed at high risk land use sites and that uses that produce these pollutants
are limited in scope, location and are required to implement safeguards to prevent release ofpollutants.
STORMWATER POLLUTANTS, SOURCES AND IMPACTS
Pollutant
Sources
Impacts
Sediment
Construction sites; eroding stream
banks and lakeshores; winter sand
and salt application; vehicle/boat
washing; agricultural sites.
Destruction of plant and fish habitat;
transportation of attached oils, nutri-
ents and other pollutants; increased
maintenance costs, flooding.
Nutrients (phosphorus, ni-
trogen)
Fertilizers; malfunctioning septic sys-
tems; livestock, bird & pet waste; ve-
hicle/boat washing; grey water; de-
caying grass and leaves; sewer over-
flows; leaking trash containers, leak-
ing sewer lines.
Increased potential for nuisance or
toxic algal blooms; increased potential
for hypoxia/anoxia (low levels of dis-
solved oxygen which can kill aquatic
organisms).
Hydrocarbons (petroleum
compounds)
Vehicle and equipment leaks; vehicle
and equipment emissions; pesticides;
fuel spills; equipment cleaning; im-
proper fuel storage & disposal.
Toxic to humans and aquatic life at
low levels.
Heavy Metals
Vehicle brake and tire wear; vehi-
cle/equipment exhaust; batteries; gal-
vanized metal; paint and wood pre-
servatives; batteries; fuels; pesticides;
cleaners.
Toxic at low levels; drinking water
contamination.
Pathogens
(Bacteria)
Livestock, bird and pet
wastes; malfunctioning septic sys-
tems; sewer overflows; damaged sani-
tary lines.
Risk to human health
leading to closure of shellfish areas
and swimming areas; drinking water
contamination.
PCBs: Polychlorinated Biphenyls
An inventory of active sites and annual inspections of high risk land uses is recommended: vehicle service
and repair shops, general service and repair shops, metalworking shops, manufacturing facilities,
waste and scrap processing and storage, laboratories and certain professional offices (medical, dental,
veterinary), salt storage and use, cleaning services, food processing plants, fueling and maintenance of
earth moving equipment, concrete, asphalt and tar manufacturer, hazardous waste facilities.
The following high risk uses are not recommended in a drinking water supply source area or other envi-
ronmentally sensitive area: hazardous waste disposal facilities, solid waste landfills, outdoor bulk stor-
age of road salt, junkyards, snow dumps, and wastewater or septage lagoons.
Reference:
Guidelines and Standard Operating Procedures Illicit Discharge Detection and Elimination and Pol-
lution Prevention/Good Housekeeping
NH Department of Environmental Services, Environmental Fact Sheet DWGB-22-3 (2020)
Vegetated Buffers
The land along the water's edge serves as a buffer against the impact of human activity on a water body,
river, stream, or wetland. The term buffer is applied widely to landscapes with different characteristics,
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ranging from naturally vegetated landscapes to undisturbed areas to those where mowing and land-
scape management is allowed. Vegetative buffers offer effective water quality treatment and a low cost.
References:
MA Audubon
New Hampshire Buffer Options for the Bay
Maryland Critical Area Commission for the Chesapeake and Atlantic Coastal Bays - Vegetative Buff-
ers
SAMPLE LANGUAGE
Definition:
A vegetated buffer is an undisturbed naturally vegetated area of land located on the development
site. The vegetated buffer can contribute to removal of pollutants when situated directly adjacent to
surface waters or a water resource, such as a lake, stream, river, pond, estuary, or a wetland.
Stormwater runoff and snow melt shall be directed to the vegetated buffer via sheet flow, collection
and distribution by a level spreader or other mechanical devise, or subsurface through perforated
pipe. Stormwater discharges to slopes greater than 10 percent are discouraged.
Reference: New Hampshire Buffer Options for the Bay
4.4.5. Climate Change Standards and Requirements
Municipalities and applicants should utilize the best available climate change science and reports to
successfully manage current stormwater runoff volumes and frequency and projected future increases
in rainfall to achieve required water quality standards and environmental protection. Recent studies
of future extreme precipitation project a minimum of a 20 percent increase in rainfall by 2050 [New
Hampshire Climate Assessment 2021], Redevelopment sites pose a particular challenge in that the
existing stormwater infrastructure (if any) is undersized to meet state and local standards and accom-
modation of current rainfall volumes and water quality treatment requirements.
References:
Cornell University Northeast Region Climate Center - Extreme Precipitation Atlas
New Hampshire Climate Assessment 2021
Metropolitan Area Planning Council - Climate Resilient Land Use Strategies
SAMPLE LANGUAGE
Applicants shall apply the best available climate change science to siting and designing development
projects {reference a data source or have applicant choose}. Stormwater infrastructure shall be engi-
neered to accommodate current and projected future precipitation volumes and plans should explicitly
reference the source of future climate precipitation data relied upon for design of the plans or in con-
formance to design standards specified by the municipality.
Stormwater runoff shall be retained on the development site to maximum extent practicable using
infiltration practices to recharge groundwater and maintain the pre-development hydrology of surface
waters and wetlands.
Climate Resilience
The Metropolitan Area Planning Council (MAPC) has created an interactive website "Climate Resil-
ient Land Use Strategies: Regulatory Language and Policy Examples" (see reference link below). The
MAPC poses this question "why address climate change through land use planning?". Most develop-
ment occurs at the individual parcel level and it's often not until a community experiences very large
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19, 2022
developments or reaches a watershed moment when development seems to envelop the community
in major change. Being proactive about land use planning is "playing the long game" that over time
may yield significant benefits. Data trends and science give us clues to our future environmental con-
ditions so why not use them to our advantage to protect our communities and their important irre-
placeable resources. Explore the topics on the MAPC website realizing that not all will resonate with
your community, but many will. Refer to the MAPC website reference for Sample/Model Language
modules.
Reference:
Metropolitan Area Planning Council https://www.mapc.org/resource-librarv/site-plan-review/
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19, 2022
4.5. Development of a Watershed Protection Standard for New and Redevelopment
Projects
A Watershed Protection Standard (WPS) was developed to provide communities with resilient alter-
native site development stormwater (SW) management performance standards designed to protect
and restore watershed and water resource health from impacts associated with future development
activities. Appendix G provides a memorandum that describes development of the WPS that defines
post-construction SW management performance standards for controlling SW runoff from impervious
cover (IC) associated with new and redevelopment activities. The WPS specifies SW control levels to
achieve predevelopment average annual groundwater recharge volumes and predevelopment SW nu-
trient load export (total phosphorus (TP) and total nitrogen (TN)). The WPS is intended to emphasize
dispersed Green Infrastructure (GI) and Low Impact Development (LID) techniques including mini-
mizing the disturbance of area with natural soils and vegetation, preservation of hydrologic function
for on-site areas of soil disturbance, and the importance of maintaining on-site predevelopment drain-
age patterns. Therefore, the WPS not only specifies levels of SW control to achieve predevelopment
recharge and SW nutrient load export on site but emphasizes the importance of the adopting the fol-
lowing site design principals for minimizing impacts and preserving natural watershed functions:
Maintain predevelopment drainage and groundwater recharge patterns.
Apply dispersed green infrastructure (GI) across site to achieve WPS performance standards
prior to finalizing design to manage for peak flow control.
Minimize disturbance of natural soils, and restore all disturbed soils not built on to predevel-
opment hydrologic conditions.
The WPS provides two options related to on-site SW runoff management for communities to consider:
1. Right sizing of infiltration SW control measures (SCMs) based on varying soil permeability
using EPA region l's SCM performance curves based on long-term continuous simulation
modelling (Boston, MA, 1992-2020); and
2. Simple one-inch (1") retention design standard for which all controls are designed to have a
Design Storage Volume (DSV) equal to 1" depth of runoff from contributing IC.
The WPS SW performance standards are derived from examining how natural vegetated land with
varying soil conditions functions under existing climatic conditions over long-periods of time. A com-
bination of continuous simulation hydrologic modeling, climatic data, research conducted in the de-
velopment of SW nutrient load export rates for the MA and NH MS4 permits, and literature on evap-
otranspiration were used to estimate SW runoff volumes, groundwater recharge, and nutrient export
conditions associated with predevelopment natural conditions and post development IC.
The conversion of natural vegetated pervious land area to IC results in lost groundwater recharge, the
process in which precipitation is captured and infiltrated into the ground. Groundwater recharge is an
essential source of water to subsurface groundwater reservoirs that supply baseflows and moisture to
surface waters and wetlands and deeper aquifer storage commonly relied upon for potable water con-
sumption. This section presents the magnitude of lost groundwater recharge volumes due to the crea-
tion of IC and the level of control needed in postconstruction SW management to replenish ground-
water recharge to predevelopment conditions.
Continuous simulation hydrologic response unit (HRU) modelling was conducted using the EPA sup-
ported Stormwater Management Model (SWMM) to estimate average annual runoff volumes for pre-
development natural vegetated land cover conditions with HSGs A, B, C and D. For this analysis,
HRU models represent unique combinations of homogenous land cover and HSG (e.g., meadow -
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FDC Phase 2, Task Order 2B: Next Generation Watershed
Management Practices for Conservation Development
Expert Report
October 19, 2022
HSG A). Two continuous simulation modelling approaches available in SWMM were used to esti-
mate annual predevelopment HRU runoff volumes for the period of interest (1992 - 2020) using Bos-
ton, MA climatic data consisting of hourly precipitation and daily temperature data.
Table 2 summarize the results of the estimated annual groundwater recharge estimates derived from
the water balance equation. This includes summary statistics of the estimates for the 29 year period
from 1992-2020 analysis period. There is considerable variability in annual precipitation and estimated
runoff and recharge values for the period of analysis (1992 to 2020). For example, annual precipitation
ranged from a minimum of 28.26 inches to a maximum of 54.46 inches and ranges of similar magni-
tude are shown for runoff and recharge volumes.
Table 3 identifies the recommended DSVs, predevelopment recharge, and the associated cumulative
SW nutrient load reduction performances for both surface bio/infiltration and subsurface infiltration
SCMs to achieve the WPS.
Table 2: Summary statistics of estimated annual runoff and groundwater recharge volumes for unit area pre-
development conditions by hydrologic soil groups (HSG) for Boston, MA climatic conditions
(1990-2022)
Measure
Precipitation Boston
HSG A
HSG B
HSG C
HSG D
Runoff,
Recharge,
Runoff,
Recharge,
Runoff,
Recharge,
Runoff,
Recharge,
Inches
MG/ac/yr
MG/ac/yr
MG/ac/yr
MG/ac/yr
MG/ac/yr
MG/ac/yr
MG/ac/yr
MG/ac/yr
MG/ac/yr
Average
42.78
1.16
0.017
0.56
0.076
0.50
0.16
0.43
0.25
0.33
Median
43.67
1.19
0.005
0.59
0.061
0.50
0.14
0.42
0.25
0.33
Minimum
28.26
0.77
0.000
0.38
0.001
0.37
0.04
0.32
0.08
0.24
Maximum
54.46
1.48
0.098
0.72
0.21
0.65
0.34
0.55
0.44
0.42
90th%
51.61
1.40
0.052
0.67
0.16
0.61
0.27
0.51
0.37
0.40
Table 3: Watershed protection standard for impervious cover stormwater management: Infiltration SCM design
storage volumes (DSVs) to achieve predevelopment groundwater recharge and SW nutrient load
export
SCM Category
SCM Types
HSG
Infiltration
Rate, in/hr
Controlling
DSV, in.
PreDevel.
Recharge*
Pre
Development
TP Export**,
DSV, in.
Pre
Development
TN Export,**
DSV, in.
WPS
Recommended
DSV, in
DSV*, in.
Surface
Infiltration
Basin, swale,
raingarden (i.e.,
bioretention),
permeable
pavement
A
8.27
0.39
0.16
0.39
0.39
0.4
A
2.41
0.67
0.32
0.67
0.60
0.7
B
1.02
0.59
0.37
0.59
0.39
0.6
B
0.52
0.73
0.45
0.73
0.42
0.75
C
0.27
0.60
0.40
0.60
0.33
0.6
C
0.17
0.69
0.49
0.69
0.35
0.7
D
O.l
0.60
0.50
0.60
0.25
0.6
D
0.05
0.86
0.86
0.80
0.30
0.9
Subsurface
Infiltration
Trench, Chambers,
drywell, tree filter
retention
A
8.27
0.60
0.23
0.60
0.60
0.6
A
2.41
1.00
0.46
1.00
0.80
l.O
B
1.02
0.86
0.49
0.86
0.53
0.9
B
0.52
0.99
0.60
0.99
0.53
l.O
C
0.27
0.81
0.55
0.81
0.38
0.85
C
0.17
0.93
0.68
0.93
0.39
0.95
D
O.l
0.79
0.72
0.79
0.25
0.8
D
0.05
1.25
1.25
1.00
0.22
1.25
* Predevelopment Recharge based on Water Balance method for Boston MA, 1992-2020 using average annual runoff yields from continuous simulaltion
hydrologic SWMM HRU models of meadow and forested lands for HSGs A, B, C and D. Predevelopment recharge conditions will be met when Infiltration
practices are sized (DSVs) to capture 66%, 63%, %51% and 40% of average annual IC runoff volumes for HSGs A, B, C and D, respectively.
**Predevelopment Nutrient export is the nutreint load delivered in surface runoff from natural wooded and meadow lands according to HSG. Required %
Reductions to IC runoff TP export are 98%, 93%, 86% and 77%, for predevelopment HSGs A, B, C, and D. Required % Reductions to IC runoff TN export are
98%, 91%, 82% and 71%, for predevelopment HSGs A, B, C, and D.
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19.2022
5. COMPENDIUM OF SITE-DEVELOPMENT STORMWATER MANAGEMENT
SOLUTIONS FOR WATER RESOURCE PROTECTION
The "Compendium" is intended
to be a useful handbook that
provides clear and concise guid-
ance on stormwater manage-
ment strategies for site develop-
ment activities to mitigate long-
term impacts associated with
the creation of impervious cover
(IC) and to preserve/maintain
natural function of vegetated
permeable on-site areas. The
target audience for the compen-
dium is local government offi-
cials with responsibilities of re-
viewing and approving site
plans. The Compendium will
emphasize dispersed Green Infrastructure (GI) and Low Impact Development (LID) techniques in-
cluding minimizing the disturbance of area with natural soils and vegetation, restoration of hydrologic
function to on-site areas of soil disturbance and the importance of maintaining on-site predevelopment
drainage patters. Examples of using the natural or restored vegetated permeable areas as part of the
on-site management of SW runoff through passive IC disconnection designs will also be displayed.
A range of scalable GI and LID Stormwater Control Measures (SCMs) will be presented on partial
conceptualized site plans at scale to illustrate the sizing(s) and location of dispersed GI LID SCM and
techniques. The purpose of the Compendium is to provide users with a range of "plug and play" SCM
options that could easily apply in many site development situations to treat various types of IC with
varying site constraints. The conceptualized GI LID designs will illustrate enough detail to display the
location and size(s) of scalable SCMs relative to IC area targeted for management. The conceptual
partial site plan will emphasize the SCM aspect of the site plan and may only display a portion of the
IC to be treated but shall include a design summary table that includes total IC area to be treated along
wife key defining design information of the SCMs sized for varying Hydrological Soil Groups (HSGs)
A, B, C, and D.
The design capacity or Design Storage Volume (DSV) of the SCMs depicted on the conceptual plans
will be set to achieve a protective level of control equal to matching predevelopment average annual
stormwater (SW) runoff nutrient load export and groundwater recharge. This level of control is ap-
proximately equal to a one (1) inch retention standard for IC runoff that would both achieve at least
a 95% reduction in average annual post-construction total phosphorus (TP) and total nitrogen (TN)
load export and predevelopment recharge targets (to be provided by EPA R1). The proposed retention
standard will include minimum infiltration requirements for attaining recharge targets. A secondary
design table will be provided on the concept plan to provide the DSV and footprint dimensions of the
illustrated control for complying with the MA MS4 post- construction requirements for TP and total
suspended solids (TSS) reductions of 60% and 90%, respectively and MassDEP's existing groundwater
(GW) recharge Standards. The Compendium will provide a section that illustrates how the depicted
SCMs are scalable so that users could downsize or upsize SCM footprints to treat varying IC drainage
areas (e.g., maintain SCM DSV and performance but treat a smaller IC area (e.g., 1 /10th acre). The
compendium will also provide the method of calculating SCM performance for adjusted DSVs |g
better suit site conditions using SCM performance curves to encourage use of multiple SCMs across a
site to achieve the overall performance standard for predevelopment drainage areas on the site (e.g.,
use of undersized and oversized SCMs on site).
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FDC Phase 2, Task Order B: Next-Generation Watershed
Management Practices for Conservation Development
Final Report
October 19, 2022
The sizing of the SCMs and estimations of cumulative performances will be accomplished by EPA R1
Opti-Tool and SCM performance curves. The conceptualized SCM plans will provide in addition to
the design details and planning level cost estimates of cumulative performances for GW recharge, and
reductions in runoff volume, and pollutant export reductions (TP, TN and TSS).
Compendium Outline:
1. Introduction and Purpose
2. Innovative Site Design Approach
3. Introduction to Watershed Protection Standard
4. Innovative Stormwater Control Measure Examples for Watershed Protection
5. Appendix A - Precipitation and Runoff By Soil Type
6. Appendix B - Rethinking Estimated Seasonal High Water Tables Limitations for
Stormwater Management
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FDC Phase 2, Task Order 2B: Next Generation Watershed Expert Report
Management Practices for Conservation Development October 19, 2022
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