Drinking water in D.C., Northern Virginia and Maryland has remained safe because of the location of the collapse of a portion of an aging regional sewer line, but day-to-day life could have been very different if the pipe collapsed a few miles upstream.
“The collapse of the Potomac Interceptor near Lockhouse 10 along the C&O Canal is downstream from intakes for the drinking water in the D.C. area,” said Michael Nardolilli, executive director of the Interstate Commission on the Potomac River Basin, which coordinates the regional water supply with Fairfax Water, WSSC Water and the Washington Aqueduct, which provides water to D.C. Water.
WTOP has learned the interstate commission has sent a letter to the regional director of the Environmental Protection Agency, requesting that D.C. Water prioritizes “repairs of the Potomac Interceptor to portions that could cause releases into the Potomac River at locations upstream of Washington Aqueduct’s Great Falls intake or other water supply intakes.”
“Normally, if it’s a minor leak of sewage, the water suppliers can add more chemicals to the water treatment facility so it doesn’t require them to shut down their intakes,” Nardolilli said. “If you have a massive leak, such as this one, which continues for a long time, that could overwhelm the ability of the water suppliers to clean the water of bacterial infections.”
Weeks after the spill, scientists from University of Maryland said water in the Potomac was still measuring E. coli 4,000 times above recreational water quality standards. In addition, they detected staphylococcus aureus and the antibiotic resistant strain of staph aureus, which is called MRSA.
“We are seeing the river recover,” Nardolilli said. “Our modeling suggests that once you actually stop the spill, the bacterial infections will go away over time.”
Five days after the spill, D.C. Water activated a bypass system to divert the release from the river into an isolated section of the C&O Canal.
During a WTOP visit Tuesday, D.C. Water’s bypass system was diverting sewage upstream of the pipe collapse into the canal, before being steered back into the Interceptor for the duration of the trip to the Blue Plains Advanced Wastewater Treatment Plant.
The utility hopes to remove boulders blocking the collapsed pipe, replace the pipe and restore the Interceptor’s normal flow in the next four to six weeks.
Commission asks DC Water to ‘focus on drinking water’
At the time of the collapse, D.C. Water had already begun the rehabilitation of the 54-mile Potomac Interceptor, which carries about 60 million gallons of wastewater from areas near Dulles International Airport, into Maryland and down to D.C.’s wastewater plant.
Since the collapse, the utility has said it would accelerate a portion of the rehabilitation after completing the emergency repairs.
“We’re concerned that D.C. Water has many, many things on their list of repairs to the Potomac Interceptor,” Nardolilli said. “We wanted to make sure they prioritize those problems with the Interceptor upstream from the drinking water intakes.”
“We want to make sure they focus on the ones that could have the most impact to the drinking water in the area,” he said.
Since the Potomac Interceptor is a federal facility, the EPA has been designated as the lead agency to provide federal oversight of the sewage line.
“The Potomac Interceptor has permits with the EPA for discharge, and so that’s the hook that we would like the EPA to use,” Nardolilli said.
In addition to prioritizing repairs, the interstate commission’s letter asks the EPA to ensure that D.C. Water provides immediate notification of any discharges from the Interceptor.
The Jan. 19 spill began at approximately 4 p.m., but Nardolilli said the group wasn’t alerted until midnight: “And that didn’t come from D.C. Water, that actually came from the Maryland Department of the Environment. We should have been notified earlier.”
WTOP is seeking comment from D.C. Water on whether the accelerated rehabilitation will include sections of the Interceptor near drinking water intakes.
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