The document discusses the impact of development on clean water, emphasizing the importance of watershed management and low impact development (LID) practices. It highlights the negative effects of urbanization, including increased runoff and water quality issues, and outlines strategies for responsible land use planning, construction, and management of existing developments. The presentation aims to provide decision-makers with insights on promoting sustainable practices to protect water resources and mitigate environmental impacts.

1. Horsley Witten Group, Inc.Horsley Witten Group, Inc.
Anne Kitchell
Horsley Witten Group, Inc.
April 2, 2014
2014 Decision
Makers
Workshops:
Construction and
Clean Water
Thinking about Clean
Water & Development

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A quick trip to www.savebuzzardsbay.org

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On today’s
agenda
• The impacts of
development
• Watershed
decisions for
decisions makers
− Where to build
− How to build
− How to manage
“the built”
• What is coming…

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The visible impacts from
existing development

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Urbanization results in
increased surface runoff
BEFORE AFTER

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Watershed impacts at~10% impervious
are well documented:
• Water quality issues
• Impacts to biological
communities
• Increased flooding
• Stream erosion
• Loss of recreational uses
• Shellfish bed closures
• Reduced recharge &
baseflow
• Wetland & contiguous
forest loss
• Increased % managed lawn

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% Impervious cover is an indicator

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Impervious Cover at the Community Scale

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8-10%
20%
30%> 65%
< 5%
As seen in the stream
% impervious

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Time (hrs)
Runoff(cfs)
Post-development
More runoff volume
Arrives faster
Pre-development
Runoff Hydrograph

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2 great (but dated) references

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Runoff WQ data from~3,800 storm events, 17 states

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Streams with <50 sq miles drainage upstream
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
% IC Upstream
%ofReference
Community
n=125
Meet WQC
Fail WQC
12% IC Threshold
% of Reference Community compares 7 metrics- Taxa Richness, Modified HBI ,
Scraper/Filterer, EPT/Chironomidae, % Dominant Taxa, EPT Index, Community Loss
Bellucci, CTDEP
Linking the Bugs to IC

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Note: Data averaged from
existing Massachusetts Estuaries
Project Reports
Contour plots of modeled total nitrogen
concentrations (mg/L) in Three Bays.
Source: MEP 2006
Pre-colonial Present Day Future Buildout

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David Johnson and Kate Morkeski load a device that feeds fertilizer into the salt marsh
on Plum Island. BOSTON GLOBE OCTOBER 18, 2012 http://www.mbl.edu/tide/data/

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Watershed Decisions
• Where we build
– Land use planning
– Land conservation
– Buffers for protected areas
• How we build
– Site Design
– Construction
– Stormwater/Wastewater
• How we manage what
has been built
– Retrofit/Redevelopment
– Pollution prevention

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How would you rate your land use planning from a
water resource protection perspective?

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How valuable are your local wetlands?
Source: Buzzards Bay Coalition website

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Do you rely on minimal state protections
or more stringent local bylaws?

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What are your disturbance thresholds for ESC?

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The problem with how we build
• More and more marginal sites are in play
• Not enough consideration for existing site
topography
• Lack of respect for native vegetation and
topsoil
• Cramming as much on site as possible based
on lot lines and zoning rather than site
constraints
• Over-reliance on engineered black boxes

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Conventional LID/New Urbanism
Is consideration of LID required in your local regs?

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Time (hrs)
Runoff(cfs)
Post-development
More runoff volume
Arrives faster
Pre-development
Runoff Hydrograph
Post-development with
detention basins to
“match the peak”
Post-development
(with LID)

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BMPs used at this site
eliminated offsite runoff
Bioretention
Bioretention
Permeable Paver
Infiltration
Chambers

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Take a look when its raining…

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Notable Local Porous Asphalt Applications

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Which of these best exhibits the LID spirit?
A
B
C D

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Lacey & Arrowhead LanesConventional vs LID?

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GI practices

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How is stormwater managed here?

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cluster layout
Jordan Cove, CT
-12 lots clustered on 6.9 acres
- Designed to minimize site runoff
Low- mow areas
Bioretention cul-de-sac
grassed swales
pervious & shared
drivewaysRain gardens
Low Impact Development
Does it really work?

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Low Impact Development
Does it really work?
Conventional
LID Cluster
Glen Brook Green (Jordan Cove)
Research/Demo Project

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Are you settling for last year’s Big Box?

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Grants Block Retrofit - Providence, RI
Morris Beacon Design
Are you taking advantage of
redevelopment opportunities?

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Cottages on Greene, East Greenwich, RI
Union Studio, Morris Beacon Design

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Which wastewater systems
are you promoting?

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Are PRBs in your future?

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What’s Coming?
• Cape Cod Commission 208 Project
• Draft Small MS4 Stormwater Permits for
Massachusetts:
– Evaluate development codes for LID barriers
– Annual tracking of impervious cover
– Retrofit inventory for municipal properties
– Program linked to impaired waters
– Stormwater standards for entire MS4, not just within wetland
jurisdiction
• Trends in new Stormwater Manuals
• Stormwater Utilities?
• Local LID by-laws?

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City of Attleboro –
Site Design Criteria
A. Use LID measures to the Max Extent Practicable
B. Document Planning Process
1. Identify and map critical resources
2. Delineate potential building envelopes that avoid
these resource areas
C. Document % Natural Open Space Retained
D. Minimize Impervious Surfaces and Document % of
Site Imperviousness
E. Disconnect Impervious Surfaces and Document %
of Effective Impervious Cover
F. Document Use of Applicable Site Design Features

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How can you require LID??!

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Can we have it all?
• Where to build
• How to build
• How to manage
what’s been built

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Us at night from space (NASA, 2012)

58. Horsley Witten Group, Inc.Horsley Witten Group, Inc.
Anne Kitchell
Horsley Witten Group, Inc.
April 2, 2014
2014 Decision
Makers
Workshops:
Construction and
Clean Water
Thinking about Clean
Water & Development
Questions?