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 1 3 2 8 8 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 2014 2016 2022

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 2013 13

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: www.dcwater.com/green

21. Irving Street Green Infrastructure Project: Contact Information For more information on the Irving Street Green Infrastructure Project, visit: www.dcwater.com/workzones/projects/irvingstreet How to reach us: Project Manager: Bethany Bezak (202) 787-4466 Community Outreach: (202) 787-4723 21