Southern California water managers want to build new systems to recycle sewage into drinking water. Little of SoCal's wastewater is currently recycled now, and there’s a good reason for that: geography.
“That’s where the rub is,” says Metropolitan Water District (MWD) chief engineer Gordon Johnson. “If you think of Southern California from the mountains down to the ocean, the elevation is falling.”
Los Angeles County’s largest treatment plant is in Carson, where it sits at sea level, taking advantage of gravity. So is the Hyperion Treatment Plant, operated by the city of Los Angeles. As a result, hundreds of billions of gallons of treated sewage is perfectly positioned to go out to sea.
“They’re kind of at the end of the water system,” says Tim Brick, managing director of the Arroyo Seco Foundation, and a retired chair of the Metropolitan Water District.
To recycle, in the short term, Metropolitan and L.A. County could pump water back up to aquifers in the foothills, where it could then percolate into groundwater aquifers.
“We’re going to be looking at different routes for the pipelines, different locations for injection wells, how to get to existing basins,” says MWD's Johnson.
Both MWD and L.A. County may start implementing some small scale, short-term fixes in 2017. The Sanitation Districts of Los Angeles County are scheduled to consider a memorandum of understanding for a pilot project next month; MWD memos suggest that the project would take 20 months to get underway.
One longer term solution under consideration? Moving the treatment plant.
“We're going to see a move towards smaller, more decentralized smaller scale plants that are closer to where we're going to see water percolated into the groundwater basins,” says Brick. “But that's 20 years away, probably.”