Recycling Wastewater

BRIAN ANDERSON, operations coordinator at the Sonoma Valley Wastewater Treatment Plant, uses his camera phone to capture the first flow of water into the newly-built, 37-million-gallon recycled water reservoir on Eighth Street East.

By Emily Charrier-Botts Index-Tribune Entertainment Editor, 1/26/12

State environmental experts agree water conservation is one of the most important issues facing California. In response, communities across the state, including Sonoma Valley, are turning rivers of raw sewage into clean water suitable for agricultural irrigation, fighting fires and even industrial air conditioners, among other potential uses.

“The water is actually certified organic,” said Brian Anderson, operations coordinator at the Sonoma Valley Wastewater Treatment Plant on Eighth Street East, which is overseen by the Sonoma County Water Agency.

Last Thursday, Jan. 19, officials at the plant turned the valve for the first time to begin filling the newly constructed 37-million-gallon, or 113-acre-foot, recycled water reservoir. The reservoir will rise at a rate of 500,000 gallons a day, meaning it will take 74 days to fill completely. The reservoir, which took six months and $3.5 million to complete, is the second in the Valley. The recycled water reservoir on Ramal Road has been servicing agriculture producers for 19 years, who pay $25 for an acre-foot of water, which measures out to about 326,000 gallons.

“It’s very reasonable … Those who have it won’t brag about it because they don’t want it catching on,” Anderson said. “Those who don’t have it are skeptical.”

The Salinas Valley, one of the largest agricultural production areas in the country, was the first to champion recycled water for irrigation purposes after the groundwater supply was so over-utilized that salty sea water was able to travel two-miles inland, threatening the clean drinking water supply. In 1980, the Monterey Regional Water Pollution Control Agency conducted the seminal research on treated wastewater, finding that it was safe to use for irrigation, which lead state regulators to approve its use on food crops.

The process for turning raw sewage into clean water has three major steps. It begins with the primary treatment, where large debris such as rags, grit and gravel are removed from the water. During the secondary process, the water is allowed to settle as microorganisms grown on site work to remove naturally occurring organic material. During the settling process, workers can remove heavy solids that fall to the bottom and grease that floats to the top. In the final and most important step, the tertiary treatment disinfects the water with chlorine before sending it through a fine screen to catch any remaining sediment. It is then pumped into an open-air reservoir, where the water is regularly tested to ensure it meets federal and state standards.

The new reservoir was specially engineered to protect wildlife. At the Ramal Road reservoir, water agency staff found coyotes, foxes and other animals that fell into the water were unable to climb out the slippery sides. The reservoirs are now outfitted with safety ladders that protect both humans and wildlife from getting trapped.

Pipelines known as purple pipes, which are separate from the pipes that transport drinking water, allow agricultural producers to access the tertiary water for irrigation. Currently, the pipeline extends from Eighth Street East to Watmaugh Road in Sonoma, but the water agency hopes to reach more customers soon. “The goal is to eventually move this water up into the Valley. We’d really like it to get to the high school,” Anderson said.

Agriculture consumes the most water in California, and Sonoma Valley is no exception. “I find all the agriculture producers that the pipeline reaches, contact them and ask if they’d like to be a user,” Anderson explained. Currently, 14 Valley agricultural producers participate in the program, and the water agency hopes more will sign on in 2012.

Ray Mulas, of Mulas Dairy, said his business has been using recycled tertiary water since the Ramal Road reservoir first opened nearly two decades ago, and he even uses it to irrigate the organic feed crops he grows, along with his family’s vineyards. He said he sees it as the best option, better than pulling water from the creeks or tapping into the groundwater tables and emptying out his neighbors’ wells.

“You’re always going to find someone who says, ‘Oh it’s bad.’ But what’s the alternative? We’re pumping out groundwater and taking water from the Russian River to irrigate crops,” Mulas said. “And then we pump that wastewater into the Bay.”

The recycled water can replace the need for well water during the warm months of May to October. From November through April, the excess recycled water is discharged into Schell Slough or Hudeman Slough, where it acts as a buffer between the salty Bay water and potable groundwater. In all, the water agency produces 30,000 to 40,000 acre-feet of recycled tertiary water yearly, about 15,000 acre-feet of which is used by customers to irrigate crops, fill decorative fountains and mix concrete among dozens of other potential uses.

Currently, agricultural producers whose fields do not connect with the pipelines can apply to truck the water to their property, further expanding the potential reach of recycled water until pipelines can be established.

“The goal is to utilize every drop of highly treated recycled water for irrigation purposes so we can rely less on the Russian River for potable water use for irrigation purposes and reduce reliance on groundwater sources,” said Brad Sherwood, spokesman for the water agency. “Groundwater is an important source we should protect and secure for our future.”

To learn more, visit www.scwa.ca.gov.