From The Editor | March 2, 2017

California And Potable Reuse's Sustainable Momentum

Peter Chawaga - editor

By Peter Chawaga

Despite recent rain inundation, California remains an epicenter for high-profile projects designed to provide residents with drinking water amidst persistent drought. The state has been a leader in the advance of desalination and potable reuse practices, investing millions in cutting-edge technology meant to bolster water sources. A new project moving forward in San Diego demonstrates that the state’s spirit of drinking water innovation is still very much alive.

The East County Advanced Water Purification (AWP) Program, a recycled water program planned to serve San Diego, recently took a stride toward completion. The program, run by the Padre Dam Municipal Water District that serves San Diego’s suburbs, has received support from its partners Helix Water District, the City of El Cajon, and San Diego County in the form of $474,000 to complete studies on the program’s viability. These funds will be put toward a $3.5 million total commitment to pursue the project. It seems that this is the level of dedication it takes to develop a sustainable drinking water program in Southern California.

“This commitment is the next step in moving the AWP program forward. Without the commitment of partners, the program could not move forward,” said a representative of Padre Dam. “There are still many things to consider as we push to implement the AWP program. The most significant considerations are financial feasibility and regulatory compliance.”

In total, Padre Dam believes that up to 30 percent of East San Diego County’s current drinking water demands could be met through this program. A first phase would purify 2.2 to 3.5 MGD, serving 6,000 households per year, and a second phase would purify 10.5 MGD, serving 26,000 households per year. As of now, the district imports all of its drinking water supply.

However, Padre Dam has a history of water recycling. It has run such programs since the 1950s and provides millions of gallons of non-potable, reused water per day to the local Santee Lakes. If the AWP program is approved, it will utilize the district’s expertise.

“Our advanced water purification technology includes four state-of-the-art processes that treat recycled water to purified water: free chlorine disinfection, membrane filtration, reverse osmosis, and advanced oxidation,” the spokesperson said.

A recycled water program could also capitalize on the community’s excess of wastewater and turn it into a positive for residents.

“The partners for the AWP program currently collect 15 MGD of wastewater,” the spokesperson said. “Most of this wastewater is currently transported to the City of San Diego’s Metropolitan Wastewater System in Point Loma, more than 20 miles away, to be treated and disposed into the ocean. The program would offload the 15 million gallons of wastewater and use it to produce purified water.”

The program will not include the still-controversial practice of direct potable reuse, during which recycled water is piped straight to consumers. The plan is to divert the recycled water through natural channels.

“For the full-scale project, the treatment process will continue with additional steps that include either injecting the water into a groundwater basin or blending it with water in the Lake Jennings reservoir,” said the spokesperson. “The water would then be withdrawn and treated again prior to being distributed as district water. The district is also considering additional brine minimization technology to maximize water supply benefits for the project.”

Padre Dam researched the world’s leading water recycling projects and incorporated successful elements into its own potential program. These lessons are things it wants to pay forward in a state that is still searching for answers to lack of water supply.

“This program could be one of the first surface water augmentation projects in California,” said the spokesperson. “Successful implementation of this program could expand augmenting water supplies for medium-sized reservoirs across the state of California.”