Napa Sanitation District (NSD) is planning a $15 million project to rehabilitate a deteriorating pipe.
The pipe that carries 90% of local sewage to the wastewater treatment plant and has no backup, reported the Napa Valley Register.
The district is making plans on how to handle the project in the summer of 2021. A system of temporary, above-ground bypass pipes is being considered, according to the Napa Valley Register.
“It’s not difficult to keep (sewage) flowing,” said NSD General Manager Tim Healy. “It’s expensive to keep it flowing.”
The 66 inch diameter concrete pipe is a half-century-old, transporting raw sewage three miles from the city of Napa to the wastewater treatment plant near the airport industrial area.
According to officials, a mile-long section of the sewage-transporting lifeline is reaching the end of its useful life, showing significant deterioration since 2012.
A comprehensive 2018 inspection confirmed that a section is structurally compromised and suggested it should be rehabilitated in the short term, according to district reports.
NSD recently released a draft environmental study for the project required under the California Environmental Quality Act, which gives details of the planned project.
Workers could also use a cured-in-place pipe, pulling a synthetic fabric liner through the existing pipe. This plan calls for setting up a system of temporary, above-ground, parallel pipes and pumps for a bypass system.
A January report listed the cured-in-place pipe with a bypass system as the preferred option.
Approvals for the rehabilitation work are needed from the U.S. Army Corps of Engineers, state Department of Fish and Wildlife, San Francisco Bay Regional Water Quality Control Board and state Water Resources Control Board.
NapaSan plans to borrow money for the project and pay for the loan using sewer service charges, reported the Napa Valley Register.
