DC Water has unveiled dramatic plans to replace 7,500ft (2,300m) of planned combined sewer overflow (CSO) storage tunnels, valued at $237 million, with green infrastructure. The controversial plan would eliminate the Rock Creek and Potomac River tunnels, which are currently included in a future phase of the $2.6 billion Clean Rivers Project.
The proposed modifications to the District’s Long Term Control Plan would see green infrastructure technology – such as rain barrels, green roofs, porous pavements and rain gardens – used on an unprecedented scale.
“The use of GI provides benefits we don’t get from tunnel construction, like increased property values, neighborhood beautification, enhancing public space, a cooling effect in the summer and creating local green jobs,” commented DC Water General Manager, George S Hawkins. “Green infrastructure will also start providing improvements to receiving water quality sooner than just the tunnel system and will ease the ratepayer burden. We hope people will agree with us and will voice their support for this approach.”
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Currently, DC Water is implementing the $2.6 billion Clean Rivers Project under the terms of a federally mandated consent decree. The first phase – which includes the Blue Plains Tunnel, the Anacostia River Tunnel, the First Street Tunnel, and the North East Boundary and Branch tunnels – is underway. These tunnels will address overflows that currently discharge about 1.5 billion gallons of diluted sewage to the Anacostia each year. Once the tunnel system is complete, in 2022, these overflows will be reduced by 98%. Later phases of the Clean Rivers Project will address overflows to the Potomac River and Rock Creek.
For Rock Creek, DC Water proposes eliminating the planned tunnel and replacing it with $60 million of green infrastructure. Implementation would begin in 2015 and be completed by 2032. For the Potomac River, DC Water proposes $30 million of green infrastructure that would begin installation in 2016 and be completed by 2028.
DC Water says this green infrastructure investment, combined with new upgrades to the wet weather treatment capacity at DC Water’s Blue Plains Advanced Wastewater Treatment facility, will allow the previously planned underground tunnel along the Potomac River to be reduced in size. The smaller tunnel would be completed in 2030. In addition, $10 million would be invested to separate the combined sewer system in designated neighborhoods.
The proposed modifications to the Long Term Control Plan (Clean Rivers Project) – which were outlined at DC Waters’ second Green Infrastructure Summit on January 22 – are subject to public consultation and amendment of the federally mandated consent decree governing deadlines in the Long Term Control Plan – a request that must be approved by the EPA and the Department of Justice.
DC Water’s announcement comes on the heels of a ceremony honoring seven design teams for their innovative plans submitted to DC Waters Green Infrastructure Challenge, which ran for most of 2013.
The Green Infrastructure Summit was held at the Metropolitan Washington Council of Governments in Washington, DC to introduce the proposal to the public and provide an opportunity for stakeholders to gain information on the 60-day public comment period process. DC Water will accept comments until March 14.