Horsley Witten Group, Inc. Stormwater Management and Elements of Low Impact Development Protecting Our Water Resources – An Ecological Approach to Land Care & Design Chatham Community Center November 16, 2013 Rich Claytor Horsley Witten Group, Inc

Horsley Witten Group, Inc. Today’s Agenda The basics of stormwater and watershed management The evolution of stormwater management towards Low Impact Development(LID) Examples of LID Practices

Horsley Witten Group, Inc. Stormwater basics Watershed Hydrology What is a watershed? A : a building for water storage B: the land area that drains to a given water body C: a shack from which fishing occurs D: a moment in time when you cross into a new area E: a new way of organizing environmental agencies

Horsley Witten Group, Inc. Stormwater basics Urbanization results in increased surface runoff BEFOREAFTER

Horsley Witten Group, Inc. Components of Impervious Cover in the Urban Landscape

Horsley Witten Group, Inc. Stormwater basics At ~10% impervious we begin to see: Water quality issues Impacts to biological communities Increased flooding Stream erosion Loss of recreational uses Shellfish bed closures Reduced baseflow and recharge

Horsley Witten Group, Inc. Community Planning LID Site Design LID BMPs Large Conventional BMPs Receiving Waters Low Impact Development (LID)

Horsley Witten Group, Inc. LID Site Planning and Design Approach Objective - to provide a process by which LID is considered at an early stage in the planning process to prevent stormwater impacts rather than mitigate them.

Horsley Witten Group, Inc. AVOID REDUCE MANAGE AVOID REDUCE MANAGE MANAGE

Low Impact Development (LID) Site fingerprinting –Preserve natural areas –Retain key pervious areas Residential –Narrow streets –Alternative turnarounds –Smart sidewalks –Shared driveways –Reduced setbacks –Open section roads –Downspout disconnection Non-residential –Pervious spillover parking –Maximum parking ratios –Shared parking –Reduced stall dimensions Traditional Design LID Mass clearing and grading –Loss of trees –Compaction of native soils Residential –Wide streets and cul-de-sacs –Sidewalks to nowhere –Lots of turf –Curb and gutter –Ponds Non-residential –Big parking lots –Minimum parking ratios –Large stall dimensions

Horsley Witten Group, Inc. Low Impact Development (LID) Site Design Traditional LID BMPs

Horsley Witten Group, Inc. Traditional controls Goal: Get the water out of here as fast as possible Collect and storage in big, “hole in ground” off- site Pipe discharge to a stream or wetland Limited water quality treatment and infiltration Stormwater is a waste product LID controls Goal: Reduce the amount of surface runoff by reducing impervious cover and preserving natural areas Rely on small, distributed on- site practices Infiltrate or reuse as much as possible; filter before discharge Source controls to minimize pollution Stormwater is a resource Low Impact Development (LID)

Horsley Witten Group, Inc. Which of these is not LID? A B CD

Horsley Witten Group, Inc. Which of these is not LID? A C D B

Horsley Witten Group, Inc. Which of these is not LID? AB C D

Horsley Witten Group, Inc. Wide streets 9 houses $ 40,400 to repave $4,500/house 14 houses $ 24,200 to repave $1,700/house

Horsley Witten Group, Inc. Which is not considered LID? AB CD

Horsley Witten Group, Inc. LID Practice Library: Bioretention

Horsley Witten Group, Inc. Bioretention Retrofit

Horsley Witten Group, Inc. LID Practice Library: Bioretention

Horsley Witten Group, Inc. LID Practice Library: Bioretention

Horsley Witten Group, Inc. LID Practice Library: Rain gardens

Horsley Witten Group, Inc. LID Practice Library: Planters

Horsley Witten Group, Inc. LID Practice Library: Tree pits

Horsley Witten Group, Inc. LID Practice Library: Porous Pavement

Horsley Witten Group, Inc. LID Practice Library: Porous Pavement

Horsley Witten Group, Inc.

LID Practice Library: Infiltration

Horsley Witten Group, Inc. LID Practice Library: Infiltration

Horsley Witten Group, Inc. LID Practice Library: Green/blue roofs

Horsley Witten Group, Inc. LID Practice Library: Green/blue roofs

Horsley Witten Group, Inc. LID Practice Library: Swales

Horsley Witten Group, Inc. Grass channel, wet, and dry swales

Horsley Witten Group, Inc. LID/GI Practice Library: Gravel wetlands

Horsley Witten Group, Inc. Resources There are many… MA Smart Growth/Smart Energy Toolkit MAPC LID checklist Town of Franklin Best Development Practices Guidebook RI Community LID Site Planning and Design Guidance Document Better Site Design Handbook (CWP) NH Innovative Land Use Planning Techniques

Horsley Witten Group, Inc. Questions?