Storm water is getting a lot more expensive for developers in Washington, D.C. In 2013, the Department of Energy & Environment (DOEE) modified its storm water management regulations to greatly increase the amount of storm water that must be managed on private property. As of July 14, 2015, the revised regulation is fully in place, and private property developers now are required to bear some of the burden—and cost—of reducing storm water runoff into the waterbodies surrounding the District. DOEE also has implemented an innovative storm water credit trading program, however, which promises to provide financial benefit, design flexibility and community benefits to District-area property developers.
The 2013 Stormwater Rule applies to two types of projects: “major land disturbing activity” (meaning a man-made change to the land surface, such as clearing, grading or excavation, that potentially changes its runoff characteristics) or “major substantial improvement.” Major land disturbing activity falls under the regulation if the project disturbs 5,000 cu. ft. or more of soil, while substantial improvement projects trigger the regulation if the structure’s footprint is 5,000 cu. ft. or greater and when renovation costs exceed 50% of the pre-project assessed value. Following the recently concluded transition period, the 2013 Stormwater Rule applies to all projects in the District that fit in one of these two categories.
Under the 2013 Stormwater Rule, major land disturbing projects are required to manage storm water runoff for a 90th-percentile storm event, or 1.2 in. of rainfall in a 24-hour period. Major substantial improvement projects must retain 0.8 in. of storm water runoff. Developers must manage this runoff with one or more of 13 DOEE-approved green infrastructure best management practices (BMPs.) Approved BMPs include green roofs, rain gardens, porous concrete, constructed wetlands and harvesting, and reuse BMPs such as cisterns—presuming all water is reused on site where it is captured.
Read the full piece below for more from Craig Holland, Director of Product Development for The Nature Conservancy's NatureVest division and Jane Silfen, Associate at EKO Asset Management Partners.