DC Water wants to pursue green infrastructure projects as a possible alternative to constructing a massive 58 million gallon storage tunnel beneath the Potomac River in Georgetown.

But Georgetown community leaders, including the Advisory Neighborhood Commission and Ward 2 Councilman Jack Evans, have expressed concerns in recent days about what would happen if that tunnel does have to be built.

Both the green infrastructure and the possible storage tunnel are part of the federally mandated effort to reduce and essentially eliminate combined sewer overflows (CSO) into the Anacostia and Potomac Rivers and Rock Creek.

In some areas of the city, including Georgetown, waste water and rain water share the same sewer pipes that flow to the Blue Plains treatment facility. When the flow of rain water and waste water is greater than the capacity of the pipes, the excess flow is discharged directly into the Potomac River. CSO is the technical term for sewage that is dumped directly into waterways.

Read: Where Your Water Goes: Part II

Between the Key Bridge and Rock Creek along the Georgetown Waterfront, there are four such CSO locations. There are also two just upstream of the Key Bridge and two more downstream of Georgetown near the Watergate and the Kennedy Center. DC Water's plan will reduce the number of CSO locations and consolidate the runoff from the locations closest to Georgetown to reduce impact on the Georgetown Waterfront. (See image)

The DC Water Clean Rivers project to address CSO is already underway with a tunnel under construction to address overflows into the Anacostia River. The Potomac River tunnel construction is scheduled to begin in 2015, but now DC Water is hoping to change its agreement with the Environmental Protection Agency to allow for testing of green infrastructure as an alternative or supplement to a multi-million gallon tunnel beneath the Potomac River. This would also potentially push back the timeline for the Georgetown area project.

DC Water's General Manager George Hawkins briefed the District Council and the Mayor on the green infrastructure project last week.

During that hearing, Councilman Jack Evans worried about would happen if the green infrastructure project was not sufficient. He is concerned about the impacts the construction of the Potomac tunnel would have on the Georgetown waterfront, including the recently finished waterfront park.

These concerns made their way to the Georgetown ANC.

"The ANC was aware of the project, but believed the project would be entirely underground and would not disturb the surface," Commissioner Ed Solomon said in a prepared statement sent to Patch.

The storage tunnels, according to DC Water documents, are about 26 feet in diameter—about the size of a Metro tunnel. The undertaking requires a tunnel borer that is so large, it must be assembled below ground and its digging could result in trucks full of dirt leaving the construction site once every minute, as Patch previously reported.

Now the ANC is also raising alarms about what impact this massive construction project might have for the waterfront area, nearby residents and local businesses.

The ANC is specifically worried about the size and placement of the shafts that would potentially need to be built to get below the river bed to build the storage tunnel.

Patch inquired with DC Water about the construction impacts on Georgetown, but was told by DC Water spokesman John Lisle that the location of a tunnel in Georgetown has not yet been determined and that there is no "detailed plan" for a tunnel.

According to Lisle, DC Water would have to do environmental studies of the potential alignment over the next several years before it would begin construction—a process that would involve the ANC and the District Council among other stakeholders.

Lisle's main point, however, was that DC Water is pushing forward with its green infrastructure option, which could negate the need for a tunnel and thereby the worry over its impacts.