Massive Sewage Leak in East Bay Marsh Resumes as Crews Try to Fix Pipe

Updated 11:51 a.m. Wednesday

Officials in Contra Costa County are still working on Wednesday to stop an underground wastewater leak that is believed to have spilled about 20 million gallons of sewage into a marsh near the bank of the Sacramento-San Joaquin Delta.

Staffers with the Delta Diablo Sanitation District discovered the leak Monday afternoon after noticing reduced inflow into their treatment plant weeks ago. The leak, coming from a pipe that carries wastewater from a storage center along its Mouse Trap-like journey to the treatment plant, has deposited nearly 1 million gallons of waste into the nearby marsh between Port Chicago and Pittsburg every day since it started.

“At a location such as this one that’s subterranean, that’s in a marshland area, it was difficult to identify on a visual basis,” said Vince De Lange, the general manager of Delta Diablo Sanitation.

Crews temporarily stopped the leak during repair work Tuesday by diverting wastewater into the Shore Acres pump station’s storage, which has an 800,000-gallon capacity. They also brought in multiple sewer-clearing trucks to remove wastewater through manholes located upstream to lessen the strain on that storage basin.

But by Wednesday morning, the pump station storage was full and repairs were still ongoing, so “sewer overflow conditions” resumed, De Lange said in an email.

The trucks do not have the capacity to offset flow completely, according to De Lange, but they helped slow the rate of Wednesday’s leakage. Three additional trucks are also being brought in from neighboring water districts.

The pipe that’s broken is a pressurized tube that carries water from a storage station to a gravity pipe, through which water flows slightly downward thanks to gravitational force. It sits about 5 feet below the grade of the land, which means a contractor has to excavate the surrounding land to reach the pipe, and then try to identify where the break occurred.

De Lange said the contractor spent much of Tuesday morning digging down to the pipe and hopes to find the break and begin working on a temporary repair, like installing a cap. He expects that work could be done by the end of Wednesday.

The sanitation district is also setting up about a mile’s worth of above-ground pipe that can bring the water from the storage station to the next gravity pipe. Materials for this fix will begin arriving on Wednesday, and it should be functional before the weekend.

“If there’s a secondary failure event or there’s another location that fails, then we have the bypass pumping,” he said. “Having the bypass pumping system in place lets us better assess the overall condition of the pipe segment … and then, if we do have to do more pronounced repair work beyond the temporary start beyond just that localized repair, if we do find corrosion in other segments, it would give us that ability to take action and make additional repairs on the line.”

The sanitation district is also conducting water tests in the Suisun Bay, which is about a quarter-mile north of the leak and connects with the San Francisco Bay to the southwest and the Sacramento and San Joaquin rivers to the east.

De Lange said it’s likely that some of the sewage has reached the Suisun Bay, especially since the Port Chicago Highway that runs to the south of the storage center acts as a kind of natural barrier to water passage, presumably pushing it up north. The water district was still waiting for test results late Wednesday morning.

The marsh is on private, Navy-owned land, but De Lange said the Delta Diablo Sanitation District still plans to post signs alerting people where the affected area is and urging them not to enter.

He said people should know that “there is a current ongoing release of wastewater, and also that there will be construction activity localized in that area as well.”

“We increased signage to warn the public of the potential for wastewater and unsafe conditions, and no body contact with that water if that’s present is advised,” added Dean Eckerson, Delta Diablo’s resource recovery services director.

They are both hopeful that between the bypass and temporary pipe repair, wastewater flow to the sanitation district’s treatment center will resume as usual in the next few days. The timeline for a permanent repair is not yet known and will depend on the location of the break.