Regional officials were briefed yesterday (Monday) on continued repairs and efforts to mitigate health risks five weeks after a sewage pipe collapsed, releasing an estimated 243 million gallons of sewage into the Potomac River.
DC Water officials outlined steps it has taken since the Jan. 19 sewer pipe collapse, just east of the American Legion Bridge, during a virtual meeting with the Metropolitan Washington Council of Governments that included Vice Chair, Mayor Alyia Gaskins. The collapse happened in a section of the Potomac Interceptor, which carries about 60 million gallons of sewage daily from Fairfax and Loudoun counties, the towns of Vienna and Herndon, Dulles Airport and Montgomery County, Md.
The company said it has stopped the overflow into the Potomac River as of Feb. 9.
“We recognize the environmental concerns raised by the residents, the environmental organizations, elected officials,” David Gadis, DC Water’s CEO and general manager, said. “One of the things we want to be clear about is where we stand today here at DC Water, and DC Water is fully diverting all wastewater away from the damaged section of the interceptor, our enhanced bypass pumping system.”
Matthew Brown, chief operating officer at DC Water, said the company estimated 40 million gallons of sewage entered the Potomac River daily from Jan. 19-24. That fell to 5 million gallons per day as DC Water activated its temporary bypass pumping system to redirect sewage.
DC Water is now working on repairing the collapsed pipe section, replacing the bulkhead and bypass chamber to handle additional flow.
“We anticipate we will have this work done by mid-March and encompasses reaching the blockage, removing the blockage and reinforcing sections of pipe upstream and downstream with the break so that we can return flow,” Brown said in the briefing. “After flows return then to the asset, that emergency repair will be done.”
The Interstate Commission on the Potomac River Basin, which provides analysis on contaminants reaching water intake locations, was requested by federal and state environmental agencies on Jan. 25 to review the break.
Cherie Schultz, a commission co-op director, noted the sewage spill occurred south of all drinking water intake locations, except for Washington Aqueduct’s Little Falls backup intake, which wasn’t in use at the time.
The City of Alexandria’s drinking water, which is sourced from Fairfax Water, remains unaffected, according to the Alexandria Health Department. On Friday, AHD said it has not seen any upticks in gastrointestinal illnesses “commonly associated with contaminated water.”
Schultz said other sections of the Potomac Interceptor upstream from water supply intakes should be prioritized for future repairs.
Testing and public health monitoring continue
E. coli bacteria testing by DC Water has been happening daily since Jan. 29 at six sites — Old Anglers Inn upstream, Drainage Channel at the overflow site, and downstream at Fletcher’s Boathouse, Georgetown at Wisconsin Avenue, Anacostia River at South Capitol Street and National Harbor. Two others were added on Feb. 18 at Minnie Island near the overflow site.
DC Water testing results from Sunday (Feb. 22) showed E. Coli levels were above the EPA-recommended limit of 410 most probable number per 100 milliliters near the Drainage Channel overflow site, Georgetown at Wisconsin Avenue and Anacostia River at South Capitol Street.
However, in and around Alexandria, provisional water testing results by the Virginia Department of Environmental Quality on Feb. 17 show levels of E. coli deemed acceptable for recreational primary contact at Jones Point Park, the City of Alexandria Marina/Torpedo Factory and Daingerfield Island/Washington Sailing Marina.
- Jones Point Park — 31 MPN/100 mL
- City of Alexandria Marina/Torpedo Factory — 31 MPN/100 mL
- Daingerfield Island/Washington Sailing Marina — 146 MPN/100 mL
Just one Alexandria testing spot, Four Mile Run at the G.W. Parkway Bridge, showed results slightly above the E. coli threshold, at 420 MPN/100 mL, according to the Virginia DEQ testing.
Elsewhere, D.C.’s Department of Energy and Environment said it is doing its own testing at three Potomac River sites and three on the Anacostia River — Fletcher’s Cove, Key Bridge, 14th Street Bridge, Washington Ship Channel, South Capitol Street Bridge and Pennsylvania Avenue Bridge. It is aiming to increase testing frequency to daily next week.
DC Water is also working with the Army Corps of Engineers and EPA to divert stormwater runoff from contaminated land to divert wastewater remnants from the Potomac River.
The Virginia Department of Health’s Feb. 13 recreational advisory remains in effect indefinitely, instructing people to avoid contact with the river.
“We’re starting to get questions about when will the recreational advisory be lifted for Virginia,” said Lance Gregory, director of VDH’s Onsite Sewage and Water Services Division. “At this point, we’re just trying to emphasize that the advisory is going to remain into effect until sustainable repairs are complete, but we are continuing to review information as that comes in and water sample data.”
Additionally, the Alexandria Health Department is working with the city to post signage around the city’s water access points — some of which, including Jones Point, fall under the National Park Service jurisdiction, prompting AHD to send signage requests, the department said on Friday.
Luke Davies, a health director with VDH, said the state agency is working in a support capacity to aid Maryland and D.C.
Officials do not believe shellfish in the lower Potomac River on the Virginia side have been impacted, according to VDH’s Feb. 17 testing. However, Schultz said environmental scientists will need to investigate sewage spill implications for the coming months and years.
“The nutrients nitrogen and phosphorous from the sewage, may increase growth of algae downstream and may increase the likelihood this summer of harmful algal blooms,” Schultz said. “Secondly, the deposition of solid sewage material on the riverbed may increase biological oxygen demand this summer in the river sediments and the likelihood of fish kills.”
DC Water said there are $600 million in repairs for the Potomac Interceptor over the next 10 years.
“It is important to note, though, that this incident does not reflect a systematic failure on the Potomac Interceptor,” Gadis said. “However it reinforces the importance of the Potomac Interceptor and the continued investment that must occur in the Potomac Interceptor for us to get to where we need to get.”
