Regional San’s monumental wastewater treatment plant expansion project delivered ON schedule and UNDER budget

SACRAMENTO, CALIF. – The Sacramento region can expect to see big changes related to how wastewater is treated and reused with the completion of Regional San’s $1.7 billion, decade-long expansion. Named the EchoWater Project, the immense upgrade was completed in spring 2023—on schedule and under budget. The result is a safe and reliable supply of treated water for discharge to the Sacramento River, which will also be used for recycled water purposes—like irrigating local agriculture and supporting habitat conservation land.

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

“Our upgraded treatment process now removes 99 percent of ammonia and 89 percent 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.”

Regional San will hold a media event marking the completion of the project on Friday, May 19, at the Sacramento Regional Wastewater Treatment Plant near Elk Grove.

About the EchoWater Project

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 percent of ammonia and 89 percent of nitrogen, addressing concerns about possible impacts downstream.

On Schedule, Under Budget

Making the project even more monumental, it came in on schedule and under budget. 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.

As with all major construction projects, punch list items will wrap up in the coming months.