Oswego Lake drawdown uncovers 10 'dead-end' pipes
City officials and lakeside homeowners have been working to map and identify several broken or disconnected pipes discovered under a group of Cabana Pointe homes that sit on pilings at the edge of Lakewood Bay.
City officials discovered the dead-end pipes earlier this month while inspecting public sewer infrastructure in the bay during an ongoing drawdown of Oswego Lake. The discovery prompted the City to issue a sewage contamination warning in the area, although Public Works Director Anthony Hooper and Wastewater Superintendent Phil Lawrence say that the warning is just a precautionary measure until the pipes can be fully inspected.
"We're just trying to bring awareness up," Lawrence told The Review, "so we posted signage that there's a sewage spill because we need to do our best practices up front and protect the public if it is."
The pipes in question are all private "laterals" — pipes that connect individual houses to the City's main lines and belong to the owners of the Cabana Pointe houses. The City alerted the homeowners about the issue, as well as the Oregon Department of Environmental Quality (DEQ) and the Lake Oswego Corporation, which controls the lake.
"They're all private, so this is not City infrastructure," Hooper said. "But since we uncovered it, it was our responsibility to make sure everyone is aware of it."
Lawrence said inspectors identified 10 questionable pipes. Three of them, which appeared to be the right diameter to be sewage laterals, looked like they traveled from the houses down to the City sewer mainline under the lake but stopped short of connecting to it.
"You've got a 4-inch ABS pipe coming down and it stopped right short of the sewer line and it's just open there," Lawrence said last week, "so we're crawling around there taking pictures, saying, 'What's this?' We don't know, so we're just trying to determine what's going on."
One of the three pipes was subsequently identified as a stormwater discharge line, which does not pose any kind of hazard, and Lawrence told The Review this week that the other two were still being mapped.
Lawrence said at least two additional pipes had turned out to be "graywater" lines that had become disconnected from the main sewer line. "Graywater" refers to water discharged from sinks, showers and appliances. It contains residue such as soap, detergent and food particulates, but not human waste.
"We do know that we had graywater going into the lake," Lawrence said. "That, we're sure of. But most of the homeowners have already contacted me or (Lake Corporation Manager) Jeff Ward, and they're making repairs."
At least four questionable pipes had the opposite problem, Lawrence said; they appeared to extend upward from the sewer main but then stopped before connecting to one of the houses.
"We don't know what they're connected to — they're just pipes coming up out of the ground," Lawrence said. "I've asked plumbers to identify what they are, and if they go to our system, then I want them capped."
According to Ward, those lines may be former Cabana Pointe sewer lines that were abandoned after an earlier project that connected the laterals to a different sewer main line. The abandoned lines should have been disconnected from the sewer main, Ward said, but since the connection is buried, it's impossible to tell whether that happened from a visual inspection.
In any case, he said, sewer systems rely on gravity to pull waste downward, so there's no risk of sewage from the main line escaping up the pipes and into the lake.
"It wouldn't be that they leak into the lake, it would be that the lake leaks into them," Ward said. "And they're trying to avoid getting too much water down in the sewage treatment plant."
Lawrence said the City has asked the affected homeowners to have licensed contractors remove any abandoned lines, cap all piping and reconnect any plumbing as needed. The DEQ has requested a final report by Dec 1, he said.
Ward said the Lake Corporation also told homeowners to try to finish repairs by Dec. 1, because that's the date when the Lake Corporation plans to begin refilling the lake, a process that will take three to four months.
"It starts out fast, especially if we have a December as wet as last year's," he said, "but then it'll slow down as it gets fuller because it gets wider and wider as it comes up."