Submitted by the Department of Agriculture

Preliminary and Final

Stream Restoration and Stormwater Management Retrofit Project

United States National Arboretum

Washington, DC _______________

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Project Information

Project summary: The District Department of the Environment (DDOE) and the U.S. National Arboretum (Arboretum) are collaborating on two related stream and watershed restoration projects on the Arboretum property in Washington, DC . The Arboretum is a 446‐acre research and education facility located in the Northeast quadrant of the District. The property is owned and operated by the U.S. Department of Agriculture, Agricultural Research Service. The first project is the restoration of Springhouse Run, an urbanized tributary of Hickey Run, which flows through the Arboretum property. The second project is a retrofit of a portion of the Arboretum’s R Street parking lot with bioretention cells to more effectively manage stormwater runoff within the Hickey Run watershed. See Figure 1 for the location of these projects. Both of these projects were born out of a December 2005, U.S. Fish and Wildlife Service (FWS) watershed assessment of Hickey Run and its tributaries. The assessment concluded that portions of the watershed are of poor quality with degraded water quality, high sediment production, and reduced riparian buffer, mostly attributable to urbanization of the watershed. This assessment noted that Springhouse Run is an incised stream with very high erosion potential, extreme sensitivity to disturbance, and poor recovery potential. The FWS assessment noted that armoring and dense riparian vegetation, which had been helping to protect the stream from erosive forces, were beginning to show signs of instability. As a result, FWS rated Springhouse Run as a “high” priority for restoration (FWS 2005). FWS followed up with the recommendations in the 2005 assessment by developing a 10% Design Conceptual Design for Springhouse Run (FWS 2007). The proposed action is restoration of Springhouse Run to a more natural stream channel including removal of several stormwater outfalls to the stream and construction of bioretention cells in the R Street parking lot to improve water quality from stormwater runoff.

Commission meeting date: April 3, 2014

NCPC review authority: Federal Project in the District of Columbia (40 U.S.C. § 8722(b)(1) and (d))

Applicant request: Preliminary and final site development plans

Delegated / consent / open / executive session: Delegated

NCPC Review Officer: J. Hinkle

NCPC File number: 7565

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Context

National Arboretum

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Project site locations within the USNA

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Springhouse Run project location

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Springhouse Run (proposed conditions—north section)

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Springhouse Run (proposed conditions—mid-section)

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Springhouse Run (proposed conditions—south section)

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Springhouse Run

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R Street parking lot

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R Street parking lot