The Sewer Authority Mid-coastside board members held an urgent meeting in the middle of a storm last week to declare a state of emergency for the local sewer system. The move allows SAM to better position itself for state and federal disaster relief funds.
During the storm that hit the San Mateo County coast on New Year’s Eve, the sewer authority’s wastewater treatment plant in Half Moon Bay was partially flooded after Pilarcitos Creek swelled over its banks. The flood came close to shutting down the plant. It submerged the plant flow meters and damaged several pumps and breakers. Staff estimated it will cost at least $15,000 to repair damages. To get an idea of how much water moved through the creek that day, one meter clocked the flow at 2,690 cubic feet per second. For comparison, on the evening of Jan. 9, before more heavy rain blew through, flow dropped to around 500 cubic feet per second.
To prepare for forecasted rain after New Year’s event and mitigate flood damage at the SAM plant, staff built a berm with tarps and stacked sandbags around the multiple entrances to electrical and effluent buildings.
“It was just a miracle the electrical system was saved,” Prathivadi said.
To protect the SAM plant from further damage during the New Year’s Eve deluge, staff temporarily shut down the Montara and Portola pump stations. This eventually caused both stations’ wet weather storage capacity to overflow. SAM's pump station in Montara has a capacity of 450,000 gallons, and Portola’s can handle 400,000 gallons. In Montara, overflow from a manhole went into the ocean for nearly nine hours. In El Granada, the Portola station flowed into the Burnham Strip, Magellan Avenue and the nearby RV park for more than two hours. Another two manholes on Obispo Road overflowed for an hour.
“We didn’t want to overrun the plant with sewer water because it was already overrun with stormwater,” SAM General Manager Kishen Prathivadi said.
On Jan. 1, SAM staff found at least four holes leaking sewage in separate parts of the Montara Force Main south of the Vallemar Pump Station on Winke Way in Moss Beach. Staff said quick emergency repairs weren’t enough to fix the leaks. Untreated wastewater went through the backyards of two houses for four hours, and flowed from two manholes outside the Montara pump station into the ocean for nearly three days — 66 hours, according to a staff report. In the meantime, four vacuum trucks sucked up water from the Montara manhole and delivered it to a pump station in Princeton around the clock, Prathivadi said.
By 11 a.m. on Jan. 4, three days after the leak was discovered, SAM staff and a contractor completed an above-ground pipeline to divert the flow. Though not an ideal situation, it was the best they could do given the circumstances and timing, Prathivadi said. It’s likely at least 300 feet of the new pipeline will have to replace the underground counterpart, which could take several weeks.
During Monday’s subsequent SAM board meeting, directors voted to continue allowing Prathivadi to make emergency procurements to deal with the fallout
from the floods. The SAM board commended the efforts of its staff, which has been working around the clock during the storms. Prathivadi noted that the SAM staff has logged a lot of weekend, holiday and overtime hours, some staying at the wastewater treatment plant overnight.
“We have fabulous staff from this community, and they really value what goes down here,” said director Kathryn Slater-Carter.
This version corrects the spelling of Kathryn Slater-Carter.
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