Historic rainfall levels have overwhelmed Baltimore’s sewer system, causing more than 45 million gallons of sewage-contaminated rainwater to flow into the city’s streams and harbor last week.
The sewage-stormwater mix — enough to fill more than 68 Olympic swimming pools — surged into the city’s waterways between July 21 and July 25, according to the Department of Public Works.
That total doesn’t take into account two additional locations where a “significant” amount of sewage continued to spew into waterways Monday, said public works spokesman Jeffrey Raymond. The overflows at those locations were caused by two separate line ruptures that occurred early last week or last weekend, he said.
Officials believe large chunks of metal debris broke off of an access road built by a contractor completing construction on the Edmondson Avenue bridge in Gwynns Falls, Raymond said. The debris then smashed into a concrete casing that was protecting two sewer pipes and ruptured the pipes, he said.
The city plans to install bypass pumping for that location once the stream subsides.
In the Maiden Choice area, a piece of debris struck a manhole stack that protrudes above the bottom of a stream behind the 300 block of South Beechfield Road, releasing sewage into the stream. Raymond said the city is going to create a bypass farther upstream to avoid the damaged stack.
It’s unclear how much sewage has escaped the two ruptures, but Raymond said the flow at both locations is “significant.”
“We’re working hard to get them bypassed and isolated,” he said.
The city said it would provide overflow data for dates after July 25 when that information becomes available.
This has been the wettest July ever in Baltimore, and the heavy rainfall is a major cause of the overflow, city officials said.
Much of the sewage-water mix was released through structured overflows that were part of the city’s sewer design more than 100 years ago. Baltimore is under a consent decree with federal and state environmental regulators to eliminate the overflows by 2022, in order to comply with the federal Clean Water Act.
In May, 10 million gallons of sewage-contaminated stormwater flowed into Jones Falls during regional flooding.
The city reminded the public on Monday to avoid contact with urban waterways because of pollution concerns.
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Baltimore Sun reporter Scott Dance contributed to this article.