Better Site Design Sustainability & Stormwater Shohreh Karimipour, P.E. NYSDEC

Presentation Outline Principles Better Site Design (LID, Sustainability, Environmental Design, Green Infrastructure) Categories Preserve Natural Features Reduce Impervious Cover Better Integrate Stormwater Treatment Principles Specific Practices

An approach to development design Better Site Design An approach to development design that seeks to: Preserve undisturbed areas Conservation Design

An approach to development design Better Site Design An approach to development design that seeks to: Reduce impervious cover Roads Parking lots Driveways

An approach to development design that seeks to: Better Site Design An approach to development design that seeks to: Use pervious areas for stormwater treatment

Conventional Site Design Good Drainage Paradigm Collect Concentrate Convey Centralized Control Good Drainage Paradigm Credit: HWG

Treatment Train Approach Rain Garden Treatment Train Approach Bioretention Cell Flow Path Grass Swale Grass Filter Strip Bioretention Cell Storm Drain System Credit: HWG

NYS Standard Practices NYS Stormwater Design Standard Overlap ( ) with BSD or LID Practices O

BSD Category one Avoid the Impacts: Preserve Natural Features and Use Conservation Design

Preservation of Undisturbed Areas Delineate on plans / in the field Place in permanent conservation: Undisturbed forest Native vegetation Stream corridors Wetlands Natural terrain – hydrology

Preservation of Buffers Delineate buffers Protect during: Design Construction Home occupancy Non-structural stormwater infiltration Consult/amend local codes US Forest Service 1

Preservation of Buffers

Reduction of Clearing & Grading Establish Limit of Disturbance for: Buildings Roads Utilities Wastewater Stormwater Use site foot-printing Limit mass grading Use open space or cluster development

Locate Sites in Less Sensitive Areas Locate development to avoid: Erodible soils Floodplains Steep slopes Wetlands Mature Forests Critical habitat GCSWCD 1

Open Space Design Use smaller lot sizes Reduce impervious cover Provide more undisturbed open space Protect water resources

Open Space Design Preserves conservation areas Preserves natural hydrology Saves costs reduces grading reduces infrastructure Successful Examples

BSD Category Two Reduce the Impacts: Reduce Impervious Surfaces

Roadway Reduction Design according to density and traffic demand Minimize roadway lengths Minimize roadway widths Consult / amend local codes Use AASHTO* guidelines Use alternative road patterns

Driveway Reduction Shared driveway Planning Board Provide Model Shared Driveway Agreement to applicants Alternative materials Shorter setbacks Encourage shared driveways Use Model Shared Driveway Agreement Encourage pervious materials on pull offs for emergency

Minimize Cul-de-Sacs Town of Wappinger §214-74 requires cul-de-sacs be circular with no center island REVISE CODE to require developers demonstrate no alternative to cul-de-sac; minimized paved area

What about New York State Highway Law? New Town roads Right-of-way = 49.5 feet If not, must petition Commissioner of Transportation Recommend: Keep 49.5 minimum – also needed for stormwater and snow removal. But limit pavement to travel-way.

Sidewalk Reduction Use alternative designs Design on one side of street only Use alternative surfaces

Building Footprint Reduction Benefits: Reduces impervious cover & pollutants

Parking Reduction Compact car spaces Minimal stall dimensions Efficient parking lanes Parking decks Porous paving in overflow Eliminate unneeded spaces

BSD Category 3 Manage the Impacts: Better Integrate Stormwater Treatment

Open Vegetated Channels Convey & treat runoff Natural drainage paths Properly designed & constructed channels On certain sites use in street right-of-way

Vegetated Buffer/Filter Strips Treat & control runoff with: Forested areas Stream buffers Vegetated filter strips

Tree Planting In stormwater management practices (where appropriate) Plant trees: In stormwater management practices (where appropriate) In landscape plans Revegetate buffer areas . . .

Infiltration O Use permeable pavement/pavers where site conditions are appropriate: Pedestrian areas Overflow parking Residential driveways Green Streets

Ecosystem function and service: Water retention and Storage

Stream Daylighting for Redevelopment Increases aesthetics Improves water quality Prevents flooding – increased storage Improves in-stream habitat Increases public use Increases property values Sunlight

Redevelopment Projects Chapter is part of Design Manual (Chapter 9) Permit coverage in 5 business days Public Noticed Application Criteria An already impervious area reconstructed, and There is inadequate space for controlling stormwater runoff, or There are physical constraints on the site Sizing Criteria 25% reduction in impervious area Treat 25% WQv with standard practice Treat 75% of WQv with Alternative Practices Combination of all the above Performance Criteria Alternative Practices (Cisterns, Rain gardens, Green roofs, Stormwater planters, Porous and permeable pavements, Select proprietary products )

Cisterns 33

Cisterns Applications Limitations Capture and store stormwater runoff for reuse or irrigation Limitations Maintenance Water use management Cold Climate Community Acceptance Sizing based on the contributing area: Vol = WQv * 7.5 gals/ft3

Rain Gardens 35

Rain Gardens Applications Limitations Manage and treat small volumes of runoff Use conditioned planting soil bed and planting material Filter runoff stored within a shallow depression Limitations Steep slopes Compacted and clay soils Sheet / shallow concentrated flow Roof drain downspout < 1,000 square feet Heavy tree cover or root systems Sizing based on WQ volume reduction

Green Roofs 37

Extensive Green Roof Intensive Green Roof

Green Roofs Applications Limitations Reducing total annual runoff volumes   Insulation from the heat and cold, energy conservation Reduce the urban heat island effect Creates habitat, aesthetically pleasing   Limitations Damage to or failure of waterproofing plant survival Maintenance Sizing based on WQv reduction, soil engineering, evapotranspiration

Stormwater Planters 41

Stormwater Planters Applications Limitations Sizing On-site soils, high GW table not suitable for infiltration  Reduction of discharge volume, velocity from impervious areas Aesthetic landscape element and micro-habitat Limitations Not designed to treat roadway runoff Overflow needs to be directed to a secondary treatment system Sizing WQV based on surface area, depth Of soil medium, hydraulic conductivity

Permeable Paving 43

Permeable Paving Porous Pavement 1 http://www.wbdg.org/design/lidtech.php Photo Copyright 1999, Center for Watershed Protection 1

Permeable Paving Permeable Pavers Applications Limitations Sizing low-traffic areas overflow parking Residential single family home GW recharge Limitations suitability of the site grades Subsoils Drainage characteristics Groundwater conditions Sizing based on surface area Photo Copyright 1999, Center for Watershed Protection 1

Summary: Improve development projects & communities with Better Site Design Preserve undisturbed areas Reduce impervious cover Use pervious areas for stormwater treatment Achieve a marketable, cost-effective product

Questions? Shohreh Karimipour, P.E. sxkarimi@gw.dec.state.ny.us (518) 402-8102 Angus Eaton, P.E. akeaton@gw.dec.state.ny.us (518) 402-8123