Implementation of SW retrofit and restoration projects in DC – lessons learned

1. Implementation of SW retrofit and restoration projects in DC – lessons learned Peter Hill DC Dept. of Health, Watershed Protection Division

2. Review of stream conditions • MS4 (storm sewer area) has extremely “blown out” streams – high sediment contribution from failing banks, high channel instability • SW infrastructure is failing (esp. headwalls) • Biological diversity is low due to urban runoff and sewer leaks • This occurs even in stream with low percentage of impervious areas

4. Sources of these problems • SW quantity not mitigated in large areas of the city • Large areas of city with no SW quality control • Aging sewer lines Fenwick Branch sw outfall Ft. Davis sw outfall (30 ft deep canyon)

5. What we’re doing…. SW retrofit prioritization • Identification and prioritization of SW retrofit sites (field determined) • Identification of estimated reduction loads • Identification of required agency buy-in • (Most difficult area)

6. LID Demonstration projects • Over 8 implemented • Over 25 in design phase • Funded with 319 and Ches. Bay Program funds

7. 1 – Bancroft ES LID 2 – Ross ES LID 3 – Human Rights Campaign Foundation green roof 4 – Casey Trees Foundation green roof 5 – Police substation rain garden 6 – Capitol Hill LID 7 – Peabody ES LID 8 – Benning Road bioretention cell

8. SW Retrofits – lessons learned Programmatic issues • More costly than expected (20-60K/biocell (.3-.6 acres treated) • DDOT right of way issues unresolved • Maintenance issues unresolved • Several agencies involved in each small project • Clear directive from agency directors has not been issued • Streamlined agency coordination has not thus been achieved Benning Rd bioretention cell

9. SW retrofits – lessons learned • Policy issues • Will this type of sw be cost-shared by the local jurisdiction? • How could these be incentivized through the permit process? Logistical/design issues • Significant space required • “Hand holding” needed • Each project unique – contractors frequently unable to modify/adapt to ensure a successful project • Issues of overflow/underdrains • Untested solutions – unexpected problems • When designed correctly – THEY WORK! Bancroft elementary SW retrofit

10. Peabody Elementary Pavers installed at school’s request Teachers sued when they were unhappy with result

11. SW retrofits - unanswered questions • Can these be projects be streamlined? • Can the city procure these projects effectively? • Is this a cost effective alternative to treat urban runoff?

12. SW retrofits – predicting costs • Back of envelope calculation….assuming that it was technically possible • 8,726 acres of paved roads, lots, alleys in DC: 22.3 % of DC land • *.67 (area not in CSO) = 5,846 acres • If average LID/biocell treats 0.35 acres, we would need 16,702 LID projects • Low cost is currently 20K/cell • Total cost for retrofitting the MS4 area= $334,040,000 • This does not account for roofs and sidewalks, only high pollutant load areas

13. DC’s Wetland restoration projects WPD has completed two large wetland restoration projects (35 & 18 acres) in the Anacostia River in partnership with the US Army Corps of Engineers. These have the promise of providing additional wildlife habitat as well as capturing nutrients and sediment. A new 7 acre project is currently under construction.

14. DC’s Wetland restoration projects- lessons learned • Removal efficiencies for wetlands are typically determined by treatment wetlands (ie.. closed system). Efficiencies for tidal systems is not known and may be much lower. • Invasive species can be a significant problem. Getting the elevation right can reduce invasive pressure by some species. • Resident Canada goose herbivory is a major problem in urban and suburban areas and can dramatically affect a wetland restoration project. Without a hunting season, it is extremely difficult to do anything about this overpopulation of an introduced species. Fencing is the typical method used to address geese, but is not a suitable long term solution.

15. DC’s Wetland restoration projects- lessons learned • USACE is experienced in wetland creation/restoration, but costs are extremely high in urban areas. $220,000-$175,000 per acre are the costs that include all ACE planning, coordination, and construction. Multi-year delays are common since funding is dependent upon congressional earmarks. • Other avenues for contracting out this aspects of this work / partnering with non-profits might be more cost effective and would involve the public more