The city’s groundbreaking ceremony Tuesday afternoon for its $89 million upgrade to its 42-year-old wastewater treatment plant emphasized the years-long process it took to begin build the most expensive public works project in Davis history.

“Davis is a community that believes in investing in the future,” Mayor Dan Wolk said.

This future involves meeting increasingly strict state regulations for the discharge of treated sewage leftovers into the environment. So-called nutrient levels — ammonia, total suspended solids, turbidity, coliform, aluminum, iron and selenium — have to be curtailed further from what’s used today with what’s called a tertiary process.

But it doesn’t come cheap.

The original cost of the upgrades was $95 million, but a low-interest state loan — at 1.5 percent — the city signed off on last month cut 6 percent off the construction price and could potentially save ratepayers more than $38 million over the next 30 years.

The city’s original price estimate came to be utilizing a design-build sequence, where the same company that designs the plans, builds the project. It’s a system with built-in savings that is not yet standard for public works projects in California, but saves significant coasts over a traditional process of hiring one company to design and another to build.

The loan is through the State Water Resources Control Board’s Clean Water State Revolving Fund. Its job is to send money to deserving local government public works projects using cash from different government sources, like the federal Environmental Protection Agency and the money paid back from other agencies that have been given loans.

“We are responsible for stewarding our environmental future, Don Saylor, Yolo County supervisor and former Davis City Council member, said. “…We want to know that our wastewater is not going to damage the environment of Yolo County or downstream.”

Saylor’s 2011 City Council approved rate hikes to pay for the new upgrades.

The surface water project uses low-interest funding from the state, as well, and was part of the calculus for the wastewater treatment plant upgrades.

“We knew we had to improve the source water before we could have a new waste facility,” Saylor said, referring to the hard salts found in many Davis water wells that will not be an issue with water siphoned off from the Sacramento River as part of the surface water project.

The public helped the city choose a plan for the sewage plant that will use recent technology to meet wastewater treatment standards.

Michael Lindquist, Davis’ wastewater upgrade project manager, has said the project called for in city plans was chosen in part for its ability to one day use recycled wastewater for irrigation. Parts of the current wastewater treatment plant also need rehabilitation.

If the state’s 40-year trend continues, city officials have said, there will be even more stringent wastewater regulations coming down from the California Legislature.

Will Arnold, a representative of state senator Lois Wolk, D-Davis, said the ceremonial groundbreaking ceremonies for public works projects have a kind of illusion to them.

“These groundbreakings feel like the beginning of something, but the folks involved know it’s the end of a long process,” he said.

After the speeches, a pile of ceremonial dirt and a row of ceremonial shovels waited for officials, workers and whoever else wanted to pose with them for photographers, while a windy day brought a fragrance from nearby wastewater ponds that could be endured with a stiff upper lip.

— Reach Dave Ryan at [email protected] Follow him on Twitter at @davewritesnews

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