Williamsburg Boulevard Green Streets Project April 27, 2011 - - PowerPoint PPT Presentation

April 27, 2011 Williamsburg Middle School

Williamsburg Boulevard Green Streets Project

What is a Green Street?

A green street incorporates facilities that reduce the impact of polluted runoff on our streams and the Chesapeake Bay.

A landscaped depression with the ability to capture, temporarily retain, and filter surface runoff A rain garden is a storm water treatment facility.

Rain Gardens

Also known as: Bioretention, Biofilter, Bioretention Filter, Bioretention Basin

Fairlington Community Center

6-12” ponding area 3” mulch Runoff

Residential Rain Garden

Ground surface 1-2’ planting soil Plants

6”- 12” ponding area 2’ - 3’ soil underdrain 1-2’ coarse gravel 3” mulch Runoff 4”- 6” pea gravel

Ground surface Overflow str Water Surface

Bioretention Rain Garden

Plants

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

Storm drain to local stream To the Potomac River On to the Chesapeake Bay

Water in storm drains does not go to a treatment plant…

Most of Arlington County developed without stormwater management

Impervious surface Runoff speed and volume Water Quality Groundwater supply Stream health

Effect of Urbanization

Stream Corridor Restoration, FISRWG, 1998

Impacts from Stormwater Runoff

Potomac River is

• ur 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.

Required Pollution Reductions Nitrogen 25% Phosphorus 24% Sediment 20% Chesapeake Bay TMDL Arlington Statistics 7125 acres of rooftop & pavement ~3500 acres to be treated by 2025

Buildings 30.1% Sidewalks 8.4% Roads 33.8% Paved median 0.6% Parking lot 15.7% Handicap ramp 0.1% Driveway 7.4% Alley 0.2% Airport 3.8%

Impervious cover in Arlington County - 2007

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 33rd and 34th Rds N

• New curbs, improved intersections and

repaving

• New canopy trees between Old Dominion
• Dr. and 33rd Rd N and between 35th St and

34th 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 ft3 (39,718 gallons)

A B

Williamsburg Bioretention Typical Cross-Section

plants 6” curb 3” mulch 3’ soil 3” pea gravel 1’ gravel 1’ 6” – 2’ 3” Max 3’ underdrain 13’ 6”

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 Black- eyed susan Little bluestem Winterberry Beardtongue Pachysandra Smooth blue aster Obedient plant

5-8” River Rock 3-5” River Rock Curb cut Concrete weir Pipe Concrete weir

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 9th 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 & 32nd St N streetscape bioretention
• John Marshall Dr median bioretention
• Patrick Henry Dr (at Inglewood) street bioretention
• 8th 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