Sewer Authority Considers Electrical Upgrades | Local News Stories

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Overcast with rain showers at times. High 57F. Winds SW at 10 to 15 mph. Chance of rain 60%..

Considerable cloudiness with occasional rain showers. Low 47F. Winds SW at 5 to 10 mph. Chance of rain 60%.

The Sewer Authority Mid-coastside board of directors last week addressed the agency’s aging electrical infrastructure at the wastewater treatment plant in Half Moon Bay and underscored the need to address ongoing flooding risks.

In an effort to protect the plant from floods due to increasingly common atmospheric rivers and high tide events, the sewer agency heard consultant recommendations on renovating its electrical systems. The board decided to give the report to member agency staff and SAM’s Planning Committee to advise the board on two of the proposed recommendations. One of them involves building a separate structure to house important electrical components.

The engineering firm TJC and Associates assessed the electrical status of the plant in 2013, but SAM has not made substantial improvements since. According to the firm, the plant’s electrical service equipment is located at the lowest part of the building, below the flood level. That means during a flood, the PG&E transformer would be partially submerged and likely interrupt power to the main service switchgear in the electrical room. The plant’s switchgear and generator are at a similar elevation and would likely be submerged in a flood, resulting in a full outage.

Engineers say the configuration and the age of the technology are out of date and put the entire plant at risk during an outage. A redesigned system would add redundancy and improve safety. One study showed that with the current layout, a portion of the plant could flood with three feet of water in more than 11 hours. In harsh wet weather, the same area could flood in less than four hours.

The first option confines upgrades solely within the electrical room. The second option involves renovating and relocating existing equipment to an elevated platform within the shop building. The third alternative proposes new switchgear and relocating a portable generator switchboard to the temporary chemical area while a new generator would go on a newly constructed elevated platform in the odor control area. Finally, the fourth alternative calls for building an entirely new structure next to the administration building to install new switchgear, a generator and relocate the existing transformer.

Consultants recommended the third and fourth alternatives as the two best methods for any upgrades. They say the chosen alternatives would avoid arc flashes and improve reliability. The perceived noise from the generator is about the same. The estimated cost of moving equipment to the temporary chemical area is about $1.94 million, while a new structure could cost upward of $2.75 million.

Jacqui Arama, the firm’s project manager, said while the fourth option is the most expensive, it would arguably be the most effective in terms of reliability and not interrupting workflow at the current plant, as the building could be constructed while keeping the current plant operational.

SAM General Manager Kishen Prathivadi told the board of directors that a new building capable of housing all electrical services would allow for the smoothest transition. He said the current electrical building is about 13 feet above sea level, and the new building’s foundation would be about 25 feet above sea level.

It’s not yet clear how long the updates would take, and some directors raised concerns that the plant needed to be secure before the next winter storms cause more flooding.

“I think we need to be realistic about the supply chain problem,” Director Kathryn Slater-Carter said. “We could be looking at long delays and price increases.”

Because building a new structure could take at least a year, the board also brought up a need to address short-term risks and groundwater flooding.

“There’s quite a bit of funding for emergency preparedness out there right now,” board member Barbara Dye said. “We should do whatever we can to get whatever we select ready to put in applications to see if we can get some grant funding.”

August Howell is a staff writer for the Review covering city government and public safety. Previously, he was the Review’s community, arts and sports reporter. He studied journalism at the University of Oregon.