Regional San completes $1.7B treatment facility expansion

May 17, 2023
The EchoWater project has helped Regional San’s expanded tertiary treatment facility to remove 99% of ammonia and 89% of nitrogen from wastewater.

California utility Regional San has completed a $1.7 billion, decade-long wastewater treatment plant expansion project.

The expanded tertiary treatment facility is now the second largest treatment plant of its kind in the nation, and the expansion project was among the largest public works projects in the Sacramento region’s history.

Named the EchoWater project, the upgrade was completed on schedule and under budget.

“Our upgraded treatment process now removes 99% of ammonia and 89% of nitrogen from the wastewater,” said Regional San General Manager Christoph Dobson. “The result is cleaner water for discharge to the Sacramento-San Joaquin Delta and a drought-resistant, recycled water source for our Harvest Water project, one of the largest ag water recycling projects in California’s history.”

The EchoWater Project began in 2010 when the Central Valley Regional Water Quality Control Board issued new treatment requirements in Regional San’s wastewater discharge permit. The Board took that action to improve water quality and help alleviate ecological problems in the Delta. To ensure effectiveness and cost efficiency, Regional San tested many possible treatment strategies to achieve the new permit requirements.

A specific strategy was selected, engineering designs were completed, and construction began. The massive upgrade consisted of 22 individual projects that together used 41,350 tons of steel and more than 225,000 cubic yards of concrete.

The centerpiece of the upgrade was the Biological Nutrient Removal (BNR) Project — the heart of the new treatment process. BNR is a sprawling complex, roughly equivalent in size to 18 football fields, and is responsible for removing 99% of ammonia and 89% of nitrogen, addressing concerns about possible impacts downstream.

The original estimate projected costs to be as much as $2.1 billion. Regional San’s commitment to the success of the project and being fiscally responsible helped keep the final cost to about $1.7 billion—drastically reducing the impact to customers’ rates. The project also received nearly $1.6 billion in low-interest financing from the state’s Clean Water State Revolving Fund, which saved ratepayers more than a half-billion dollars in interest costs.

Regional San treats an average of 135 million gallons of wastewater each day from 1.6 million people throughout Sacramento County and West Sacramento.