Green infrastructure to help DC reduce sewer overflows under revised strategy

The Environmental Protection Agency, District of Columbia and DC Water have announced an agreement to modify a 2005 federal consent decree that allows DC Water to incorporate green infrastructure in its long-term strategy for curtailing combined sewer overflows.

PHILADELPHIA, PA, May 20, 2015 -- Today, the Environmental Protection Agency (EPA), District of Columbia (District) and DC Water announced an agreement to modify a 2005 federal consent decree (CD), allowing DC Water to incorporate green infrastructure in its long-term strategy for curtailing combined sewer overflows (CSOs).

The modification, recently filed in Federal District Court, allows DC Water to pursue an integrated green/gray infrastructure approach to address water quality issues in the Rock Creek and Potomac watersheds resulting from CSOs. This integrated approach utilizes green infrastructure in a targeted and sound engineering manner to reduce these overflows. Green infrastructure uses vegetation, soils and natural processes that mimic nature to store rainwater water where it falls to control wet-weather pollution and create healthier urban environments.

The green infrastructure projects in Rock Creek and Potomac watersheds are slated to begin in 2015 and 2016 respectively, providing more immediate pollution reductions, enhancements to community livability, and green jobs opportunities. Specifically, the CD modification includes:

  • Potentially eliminating the Rock Creek storage tunnel and significantly decreasing the size of the Potomac tunnel, depending upon the success demonstrated by green infrastructure.
  • The District providing the public space necessary for DC Water to construct the proposed green infrastructure projects and making changes to District regulations, codes, standards, guidelines, and policies needed for implementation.
  • Requiring the District and DC Water to work together to coordinate capital projects and expenditures for implementing green infrastructure, enabling the efficient use of resources and minimizing costs to ratepayers and taxpayers.

As part of the agreement, DC Water will have an additional five years to complete implementation in the Potomac and Rock Creek watersheds beyond those provided for in the original 2005 CD, which established a compliance schedule to construct tunnels in the Anacostia, Potomac and Rock Creek watersheds. The schedule for completing the Anacostia tunnel remains unchanged.

Under this CD, DC Water will continue moving forward on the construction of the overall CSO control project, known as the Clean Rivers Program. This project involves completion of control structures and tunnels for the Anacostia watershed, which contributes more than 65 percent of the sewage discharged to District waters annually. Major portions of this tunnel system are scheduled for completed and in operation in 2018. When the complex is fully completed in 2025, it will nearly eliminate CSOs to the Anacostia in an average rainfall year.

In November 2011, DC Water proposed to incorporate green infrastructure into its overflow control strategies for the Potomac and Rock Creek watersheds. As part of the request, DC Water submitted analysis demonstrating that modified CSO controls in the Potomac and green infrastructure in Rock Creek could provide equivalent pollution reductions to those in the original plan and were economically feasible. In early 2014, after conducting a public participation process, DC Water also filed a request to EPA to modify the plan for CSO controls and deadlines set forth in the 2005 CD.

See also:

"DC Water announces successful sale of $350M green century bonds"

"DC Water awards Parsons massive tunnel design-build contract for Clean Rivers Project"

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