Stormwater Retention Credit Trading Program
The former Shaed Elementary School is located on a small site in northeast Washington, D.C. In 2014, the nonprofit Building Hope leased the school, which had closed because of low enrollment, and an extensive renovation of the building began. This improvement project triggered the city’s stormwater regulations and led to the first Stormwater Retention Credit (SRC) trade in Washington, D.C., when the District Department of Energy & Environment approved the transfer of 11,013 SRCs for a value of approximately $25,000. “It was a tradeoff,” Tom Porter of Building Hope explains, “between carrying out a complex and expensive green infrastructure project and buying credits.” The school’s modest size and structural limitations made it difficult for Building Hope to meet the required 11,013 credits on site.
Almost 31,000 square feet of this 39,413-square-foot lot is composed of impervious surfaces, and the foundational work required for a green roof or bioswale would increase the initial costs of green infrastructure to over $100,000. The Shaed Elementary School bought credits from the Westchester, a co-op apartment complex located in northwest Washington. A person involved in the trade says the initial cost of installing rain gardens on the property, including engineering plans, was close to $75,000. Thus far, the Westchester has generated more than $70,000 in income by selling SRCs. “Revenue from this trade will help cover the costs of designing, installing, and maintaining the rain gardens that generated the SRCs,” the seller of the credits says. “Now we’re looking at other ways to install practices on our property to generate additional SRCs.” In addition, the Westchester is entitled to receive a discount for the stormwater portion of its monthly water bill, which is quite a significant savings for a property of 11 acres.
Ecologically, the trade fits nicely into the city’s plan to encourage more green infrastructure where it is most needed. The Westchester is located in an area served by a municipal separate storm sewer system, or MS4, where stormwater runs directly into the city’s waterways without any filtration or treatment. Green infrastructure is especially important for water quality in these areas. The Shaed Elementary School, by contrast, is served by a combined sewer system that brings both sewage and rainwater to the city’s Blue Plains Advanced Water Treatment Plant. The SRC trade between the Shaed Elementary School and the Westchester, therefore, is a successful example of the main purpose of the SRC program: to shift investment in green infrastructure to MS4 areas of the District.