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District of Columbia Water and Sewer Authority George S. Hawkins, General Manager September 7, 2014 Rainwater Harvesting: Update on Bioretention at Wangari.

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Presentation on theme: "District of Columbia Water and Sewer Authority George S. Hawkins, General Manager September 7, 2014 Rainwater Harvesting: Update on Bioretention at Wangari."— Presentation transcript:

1 District of Columbia Water and Sewer Authority George S. Hawkins, General Manager September 7, 2014 Rainwater Harvesting: Update on Bioretention at Wangari Gardens Briefing on:

2 Agenda  Background: Stormwater Runoff & CSOs  Background: Plan to Mitigate Flooding  DCCR Irving Street Green Infrastructure Project  Purpose  Bioretention Locations  Benefits  Example of Plant Palette  Maintenance  DC Water’s Proposed GI Plan 2

3 Background: Comparing Natural vs. Built Environment Natural Environment (0% Impervious Surface) Built Environment (75-100% Impervious Surface ) 3

4 Background: Why is stormwater runoff a problem? Stormwater:  Carries trash, excess nutrients (such as nitrogen and phosphorus), sediment and other pollutants;  Impacts waterbodies we use for swimming, fishing and providing drinking water. 4

5 Background: Separate and Combined Sewer Systems 100% of suburbs 67% of D.C. 0% of suburbs 33% of D.C. Including Bloomingdale 2 pipes 1 pipe 5

6 Background: Northeast Boundary Combined Sewer Drainage Area  The Northeast Boundary Drainage Area has been historically prone to combined sewer overflow (CSO) flooding issues.  The Bloomingdale Drainage Area is located in the northern portion of the Northeast Boundary Drainage Area.  Stormwater runoff from this drainage area contributes to flooding events experienced just north of the Northeast Boundary Trunk Sewer. Bloomingdale Flood Areas 6

7 Background: Mayor Gray’s Task Force PersonAffiliation Allen Lew, Co-ChairCity Administrator George Hawkins, Co-ChairDC Water General Manager Kenyan McDuffieWard 5 Councilmember Jim GrahamWard 1 Councilmember Terry BellamyDept of Transportation, Director Keith AndersonDept. of the Environment, Interim Director William HowlandDept. of Public Works, Director Chris GeldartD.C. Homeland Sec. & Emergency Manag., Director Nicholas MajettDept. of Consumer & Regulatory Affairs, Director Dr. Saul LevinDept. of Health, Director William WhiteDept. of Insurance, Securities & Banking, Director Eric GouletOffice of Budget and Finance, Budget Director Serita SandersBloomingdale neighborhood representative Teri QuinnBloomingdale neighborhood representative Myla MossLeDroit Park neighborhood representative Engineering Task Force Members Regulatory Code Changes O&M Public Outreach McMillan Storage First St Tunnel Northeast Boundary Tunnel 7

8 Background: Three-step Infrastructure Solution To Mitigate Flooding 8 Irving Street Green Infrastructure and McMillan Stormwater Storage - 4 million gallons First Street Tunnel – 8 million gallons Northeast Boundary Tunnel Irving St Michigan Ave Rhode Island Ave First St. North Cap. St North Capitol Tank & Diversion Structure Channing St. First St Tunnel Connect Diversion Chamber to First St Tunnel Northeast Boundary Tunnel Bioretention (Green Infrastructure) along Irving St First St Diversion Chamber Legend

9 Irving Street Green Infrastructure Project: Purpose  To help mitigate flooding in the Bloomingdale area, the DC Clean Rivers Irving Street Green Infrastructure Project included:  Installation of 14 bioretention facilities  Located along Irving Street corridor between Michigan Avenue and North Capitol Street 9 Flooding in Bloomingdale and LeDroit Park Recently planted bioretention

10 Irving Street Green Infrastructure Project: Bioretention Locations Old Soldiers’ Home Irving St Park Place NW First St Bioretention Locations (typical) Washington Hospital Center N 10

11 Irving Street Green Infrastructure Project: Bioretention Overview  What is Bioretention?  A planted filter bed of specialized soil, sand, and stone aggregate  Basins are typically slightly depressed into the surrounding landscape to facilitate runoff flow to the system  Also referred to as rain gardens  Formal or informal aesthetic (i.e., street side tree box vs. naturalized garden)  Purpose/Benefits:  Stormwater runoff is slowed, cooled, filtered and infiltrated  Reduced flooding  Plants and soil remove contaminants and excess nutrients Photo courtesy: Daily Journal of Commerce Photo courtesy: Dennis Carmichael ~10’ (typ.) ~25’ (typ.) Example Bioretention: Street Side Tree Box Example Bioretention: Naturalized Garden Photo courtesy: Daily Journal of Commerce Photo courtesy: Dennis Carmichael 11

12 Irving Street Green Infrastructure Project: Bioretention Overview (Cont.)  Additional Benefits:  Provide habitat  Establish shade and cooling of surrounding areas  Create community amenity and enhance green space  Improve air quality 12

13 Irving Street Green Infrastructure Project: Typical Bioretention Cross Section Cross section courtesy: DDOE Stormwater Management Guidebook

14 Irving Street Green Infrastructure Project: Bioretention at Wangari Gardens For Bioretention at Wangari Gardens and along Irving Street:  Stormwater collected in the basins will pond to a depth of up to 12”  Stormwater then filters through a soil media layer which removes contaminants.  Stormwater is then stored in a deep layer of stone and detained there until it is released into the underdrain and ultimately back into the sewer. 14 Recently planted bioretention

15  Grasses: Provide texture and seasonal interest year round.  Perennials: Flowers provide diversity of color during the growing season. Irving Street Green Infrastructure Project: Plant Selection Examples Coastal Panic GrassLittle Bluestem Foxglove Beardtongue Black-eyed Susan Switchgrass Photo courtesy: Chhe Wild Blue Indigo Photo courtesy: Denis Prevot Photo courtesy: USDA-NRCS PLANTS Database Photo courtesy: Chhe Photo courtesy: D. Gordon E. Robertson Photo courtesy: Lorax 15

16  Shrubs: Provide texture and form to bioretention areas.  Trees: Provide shade and canopy adjacent to the bioretention facility. Flowers and fall foliage enhance bioretention aesthetics. Irving Street Green Infrastructure Project: Selection Examples (Cont.) Redosier DogwoodNorthern Bayberry Eastern RedbudFringetreeBlack Gum Photo courtesy: Jean-Pol Grandmont New Jersey Tea Photo courtesy: H. Zell Photo courtesy: Greg Hume Photo courtesy: USDA-NRCS PLANTS Database Photo courtesy: Chhe Photo courtesy: Derek Ramsey 16

17 Irving Street Green Infrastructure Project: Bioretention Planting Establishment Example Bioretention Immediately Following Planting Bioretention After 1 Growing Season Bioretention During 2 nd Growing Season Photo courtesy: Seattle Public Utilities 17

18 Irving Street Green Infrastructure Project: Maintenance and Monitoring DC Water will perform ongoing maintenance to ensure long-term performance of the facilities, such as:  Remove trash, sediment and animal waste  Weed and prune plants  Inspect cleanout pipes and underdrains  Inspect and treat vegetation for disease and pest problems Pre/post construction monitoring will provide data to improve future Green Infrastructure design, construction, operation and maintenance. 18

19 Irving Street Green Infrastructure Project: Signage  Signage has been placed at each bioretention location providing contact information for inquiries. 19

20 Proposed Green Infrastructure Plan: What is Proposed for Potomac and Rock Creek? $60 M of Green Infrastructure in Piney Branch $30 M of Green Infrastructure in CSO 027, 028 and 029 Separate CSO 025 and 026 ($10 M) 20 For more information on DC Water’s Green Infrastructure Plan, visit:

21 Irving Street Green Infrastructure Project: Contact Information For more information on the Irving Street Green Infrastructure Project, visit: How to reach us: Project Manager: Bethany Bezak (202) Community Outreach: (202)


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