On Jan. 22 at the District of Columbia Water and Sewer Authority’s (DC Water) second Green Infrastructure Summit, General Manager George Hawkins announced a proposal to substitute green infrastructure for some of the massive underground tunnels in DC’s Long Term Control Plan for combined sewer overflows (CSOs).
The new plan will green portions of the city on a scale unprecedented for the District, calling for a $100 million investment in green infrastructure. Proposed modifications to the city’s $2.6-billion CSO consent decree, known as the Clean Rivers Project, have been released for public comment.
The first phase of the Clean Rivers Project is already underway. Average annual CSOs to the Anacostia River currently total about 5.7 billion m3 (1.5 billion gallons), but a massive underground tunnel system is intended to reduce those CSOs by 98% when completed in 2022.
Tunnels also were planned to address overflows to the Potomac River and Rock Creek. However, under the newly proposed hybrid approach, the Rock Creek tunnel would be replaced with $60 million of green infrastructure. Implementation would begin in 2015 and be completed by 2032.
For the Potomac River, DC Water proposes reducing the tunnel size, using $30 million of green infrastructure coupled with an increase in wet weather treatment capacity at DC Water’s Blue Plains facility. The smaller tunnel would be completed in 2030 while green infrastructure installation would begin in 2016 and be completed by 2028. In addition, $10 million would be invested to separate the combined sewer system in designated areas.
This announcement comes on the heels of a ceremony honoring seven design teams for their innovative plans submitted to DC Water’s Green Infrastructure Challenge, which ran for most of 2013. DC Water will award more than $1 million for the two phases of the Challenge — design and construction.
The 60-day public comment period is open until 5pm (EST) March 14, 2014. Comments can be submitted to CleanRiversGI@dcwater.com.