The D.C. Blue Plains Advanced Wastewater Treatment Plant is a small wonder and a friend of the environment. At least that's what DC Water General Manager George Hawkins tried to express to a group of reporters recently. But Georgetown's outdated sewer system leaves something to be desired. Changes coming over the next 15 years will allow Blue Plains to process more wastewater and improve the quality of the Potomac River.

The Blue Plains facility in SW D.C. serves the District, MD and VA for a total of 726 square miles of coverage and has the capacity to treat 370 million gallons of wastewater a day. 

In D.C. alone, DC Water operates 1,800 miles of sanitary and combined sewers. Georgetown's historic buildings and the age of the established neighborhood mean the area has combined sewers that receive both storm water and wastewater; newer neighborhoods  have separate sanitary and storm water sewers.

The difference matters most when rain and snow lead to higher than normal flows. On these days the Combined Sewer Overflow (CSO) is greater than the capacity of the pipes that carry the wastewater and storm water to Blue Plains. This excess flow, both storm runoff and wastewater, is discharged directly into the Potomac River. 

There are 60 CSO locations in the District that flow into the Potomac and Anacostia Rivers as well as Rock Creek. In a given calendar year there are 3 billion gallons of overflow; 2 billion flows into the Anacostia River and 1 billion flows into Rock Creek and the Potomac River combined.

In 2002 DC Water finalized a Long Term Control Plan (LTCP) to address CSO. The plan will reduce CSO in the Potomac in several ways. First, DC Water is in the process of rehabilitating the Potomac Pumping Station, located at the foot of the Roosevelt Bridge's east end. Second, the plan will reduce the number of CSO locations and consolidate the runoff between the Key Bridge and Rock Creek to reduce impact on the Georgetown Waterfront.

The third and most extensive effort will be the creation of the Potomac Storage Tunnel. The 58 million gallon tunnel will carry wastewater and storm water from Georgetown to the upgraded Potomac Pumping Station.

The massive tunnels will be 26 feet in diameter. The size of a Metro tunnel, the Potomac Storage Tunnel, along with similar planned tunnels in other areas of the District, will be made with the same drill used to dig a metro tunnel. Hawkins described a massive project with workers taking trucks of dirt off the site every minute. The giant machine for such a job will have to be assembled under ground.

Hawkins said the Anacostia plan will be implemented first and should complete in 2018. The Rock Creek and Potomac phases of the plan should begin in 2015 and be complete by 2025. The entire LTCP should cost an estimated $2.6 billion.