Williamsburg Boulevard Green Streets Project April 27, 2011 Williamsburg Middle School
What is a Green Street? A green street incorporates facilities that reduce the impact of polluted runoff on our streams and the Chesapeake Bay.
Rain Gardens A landscaped depression with the ability to capture, temporarily retain, and filter surface runoff A rain garden is a storm water treatment facility. Fairlington Community Center Also known as: Bioretention, Biofilter, Bioretention Filter, Bioretention Basin
Residential Rain Garden Plants Runoff Ground surface 6-12” ponding area 3” mulch 1-2’ planting soil
Bioretention Rain Garden Runoff Plants Overflow str Water Surface Ground surface 6”- 12” ponding area 3” mulch 2’ - 3’ soil underdrain 4”- 6” pea gravel 1-2’ coarse gravel
Why Rain Gardens? Traditional stormwater management isn’t as effective at protecting water quality. Many localities are using new stormwater management techniques where possible to improve water quality. Woodmont
Most of Arlington County developed without stormwater management Storm drain to local stream To the Potomac River Water in storm drains does On to the not go to a treatment plant… Chesapeake Bay
Effect of Urbanization Impervious surface Runoff speed and volume Water Quality Groundwater supply Stream health Stream Corridor Restoration, FISRWG, 1998
Impacts from Stormwater Runoff Potomac River is our source of drinking water. Stormwater runoff erodes local streams, carrying sediment downstream, killing trees, and damaging sewer lines.
Regulatory Requirements Virginia Stormwater Permit requires us to reduce stormwater pollution from existing and new development. Permit require- ments are becoming more stringent. Chesapeake Bay TMDL in development. Master Transportation Plan includes recommendations for street trees and reduction of stormwater runoff.
Chesapeake Bay TMDL Required Pollution Reductions Nitrogen 25% Phosphorus 24% Sediment 20% Arlington Statistics 7125 acres of rooftop & pavement ~3500 acres to be treated by 2025
Impervious cover in Arlington County - 2007 Airport Alley 3.8% 0.2% Handicap ramp 0.1% Driveway 7.4% Buildings 30.1% Parking lot 15.7% Paved median 0.6% Sidewalks 8.4% Roads 33.8%
Stormwater Master Plan Update Storm Sewer Capacity Analysis County-wide stream inventory Watershed retrofit plans to identify locations where stormwater treatment facilities can be added to help slow down and filter stormwater runoff. Each plan contains an inventory of projects. Rain gardens Removing pavement/impervious surface Little Pimmit Run Watershed Retrofit Plan http://www.arlingtonva.us/departments/Environment alServices/cpe/page75627.aspx
Project Components Two 1000+ square foot rain gardens between 33 rd and 34 th Rds N New curbs, improved intersections and repaving New canopy trees between Old Dominion Dr. and 33 rd Rd N and between 35 th St and 34 th Rd N.
Williamsburg Rain Gardens A – 4 sections B – 3 sections AS- Allegheny Serviceberry; RB – Red Buckeye
Williamsburg Rain Gardens A – 4 sections B – 3 sections
Williamsburg Rain Gardens
Rain Garden Drainage Areas Total drainage area: 1.8 acres Impervious area treated: 1.1 acres Water treated: 5310 ft 3 (39,718 gallons) A B
Williamsburg Bioretention Typical Cross-Section 13’ 6” plants 6” curb 3” mulch 3’ soil 1’ 6” – 2’ 3” 3” pea gravel Max 3’ 1’ gravel underdrain
Trees and Plants 12 trees and 2 shrubs will be removed Includes 3 mature trees (> 10 dbh) – all exhibiting signs of stress 7 canopy trees; 9 small trees and multiple shrubs will be planted Numerous flowering perennials, grasses and vines All plants will be native, salt tolerant
Red buckeye Smooth blue aster Black- eyed susan Obedient plant Winterberry Beardtongue Pachysandra Little bluestem
Concrete Curb cut Pipe 5-8” weir River Rock Concrete weir 3-5” River Rock
Maintenance Initially, after any large storms Thereafter, quarterly Remove sediment Weed, inspect, replant, prune plants Remove trash Make sure underdrain, overflow all working correctly
Next Steps Choose plants and finalize planting plan Peer engineering review and subsequent revisions Utilities Construction: Fall-Winter 2011
Green Streets Projects 209 projects identified to date 1 in construction Patrick Henry Dr (at 9 th Rd N) – median bioretention • 7 projects in planning or design • Williamsburg Blvd median bioretention Old Dominion to 35th St N Harrison to Edison N (NC project) • Kensington Blvd & 32 nd St N streetscape bioretention • John Marshall Dr median bioretention • Patrick Henry Dr (at Inglewood) street bioretention • 8 th St S streetscape bioretention • Pentagon City streetscape & median bioretention
Questions?? Contact info: Phone: (703) 228-3588 Email: cjolicoeur@arlingtonva.us Web: www.arlingtonva.us Residents Environment Watershed Management http://www.co.arlington.va.us/departments/Environ mentalServices/epo/page74076.aspx
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