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DC Water Proposes Modifying Clean Rivers Project for Green Infrastructure

DC Water is modifying its Long Term Control Plan (LTCP) to incorporate a large investment in green infrastructure. Detailed information on the proposal is below.


Under the terms of a legal agreement between DC Water, the District of Columbia, the U.S. Department of Justice (DOJ) and the U.S. Environmental Protection Agency (EPA), DC Water is implementing the $2.6 billion Clean Rivers Project. The first phase of the project is underway and involves constructing a massive underground tunnel system to control combined sewer overflows to the Anacostia River. These overflows, which currently discharge about 1.3 billion gallons of diluted sewage to the Anacostia in an average year, will be reduced by 98 percent when the tunnel system is completed in 2022. The later phases of this plan included construction of similar tunnels to control overflows into the Potomac River and Rock Creek.

Since 2011, DC Water has explored the use of green infrastructure as a tool to reduce combined sewer overflows to the Potomac River and Rock Creek. Green infrastructure technologies mimic natural processes by capturing, slowing, and cleaning stormwater before it enters DC Water's combined sewer system. Green infrastructure technologies like green roofs, porous pavement and rain gardens provide greater benefits to the community than the previous plan to construct only underground tunnels for the Potomac River and Rock Creek.



On May 20, 2015, DC Water, the District of Columbia, EPA, and DOJ announced an agreement to modify a 2005 legal settlement to allow for large-scale green infrastructure installations and other modifications to the Clean Rivers Project impacting the Potomac River and Rock Creek.

Under the modified agreement, DC Water will eliminate the previously-planned underground tunnel for Rock Creek and will instead build green infrastructure and targeted sewer separation to manage the volume of runoff produced by 1.2" of rain falling on 365 impervious acres of land that currently does not absorb stormwater. This portion of work will be completed by 2030.

For the Potomac River, DC Water will build an underground tunnel capable of holding 30 million gallons of combined stormwater and sewage. The tunnel will use gravity to allow the collected combined sewage flow to DC Water's Advanced Wastewater Treatment Plant at Blue Plains and will be completed by 2030. In addition, DC Water will construct green infrastructure and targeted sewer separation to manage the volume of runoff produced by 1.2" of rain falling on 133 impervious acres of land that currently does not absorb water. The green infrastructure in this area will be in place by 2027 and sewer separation will be complete by 2023.

When the LTCP was finalized in 2002, there was no effluent limit for total nitrogen in DC Water's discharge permit for the Blue Plains Wastewater Treatment Plant. In 2007, EPA modified DC Water's permit to include a lower nitrogen limit to improve the Chesapeake Bay. DC Water evaluated a range of controls and developed a plan that involved adding 31 million gallons of storage to the LTCP tunnels and constructing an enhanced clarification treatment system at Blue Plains to allow practical removal of nitrogen. This plan is called the Total Nitrogen/Wet Weather Plan or TN/WW Plan. DC Water is proposing to modify the LTCP to incorporate the changes made by the TN/WW Plan, as well as certain other changes that have occurred since the LTCP was finalized. EPA and the District have accepted the projects in the TN/WW Plan and DC Water has been implementing it since 2007. These changes were approved by EPA and DOJ in 2009, but they have not yet been incorporated into the LTCP.



Sooner. Unlike a massive underground tunnel system, green infrastructure provides water quality benefits as soon as installation begins. The green infrastructure and other improvements will allow the District to enjoy water quality and environmental and social benefits as early as 2017.

Better. Green infrastructure offers environmental, social, and economic benefits that would not be realized under the previous plan. Green infrastructure can increase property values, beautify neighborhoods, cool extreme summer temperatures, support natural habitats, enhance public space and support local green jobs.

Stronger. DC Water's proposed schedule for green infrastructure implementation and construction of the redesigned Potomac River Tunnel helps reduce the impact of construction on neighborhoods and allows sufficient time for required construction approvals. The revised schedule allows for an additional five years to complete portions of the project. This additional time will help protect our ratepayers responsible for financing the $2.6 billion project.

Jobs. DC Water will establish an ambitious local jobs program that includes training and certification opportunities for District residents interested in green infrastructure construction and maintenance jobs. DC Water has established a goal to have 51% of new jobs created by the green infrastructure project filled by District residents. DC Water will also engage professional service firms and contractors based in the District to perform work associated with green infrastructure.





GI Documents

What is Green Infrastructure? (PDF 3.9 mb)
Green Infrastructure Modification Fact Sheet (PDF 1.8 mb)
Executive Summary for Green Infrastructure (PDF 2.5 mb)
Full Green Infrastructure Modification Document (PDF 39.0 mb)
Green Infrastructure Briefing Slides (PDF 3.5 mb)
Green Jobs MOA (PDF 773 kb)
Green Infrastructure Certification Program Scope (PDF 3.3 mb)
Green Infrastructure Mentor Internship Program (PDF 194 kb)
Green Infrastructure Program Plan (PDF 23.9 mb)
Project Description - Rock Creek Project A (PDF 9.1 mb)
Project Description - Potomac River Project A (PDF 9.6 mb)

Total Nitrogen / Wet Weather Plan
Executive Summary for Nitrogen Removal (PDF 1.5 mb)
Summary Document for Nitrogen Removal (PDF 14.9 mb)

Sempervivum Care Instructions (PDF 90 kb)
Green Infrastructure Overview Materials (PDF 4.4 mb)


Frequently Asked Questions

What is the purpose of this initiative?

What is the Consent Decree?

What is Green Infrastructure?

What are the benefits of Green Infrastructure?

What alternative is DC Water proposing?

What is a Combined Sewer Overflow?

How many CSO outfalls currently exist?

What is the DC Clean Rivers Project?

What progress has already been made in CSO control?

What is DC Water proposing?

When will we start implementing GI?

What are the benefits of the proposed plan?

What does DC Water need to do to make the Consent Decree and other necessary sewer and wastewater improvements affordable?

How did DC Water determine the number of acres to that will be managed by GI and targeted sewer separation?

How much will be saved by changing the schedule?

Is there any downside to changing the schedule?

Why is time needed to implement the hybrid GI approach for the Potomac River and Piney Branch?

What is the benefit of an adaptive management approach?

Why does DC Water need additional time?

Why is a time extension in the public interest?

Where can I obtain more information?

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