Escondido is moving forward on a reverse osmosis treatment facility that will reduce the city’s wastewater and also provide more recycled water for agricultural use.
The project will divert millions of gallons of water from the discharge pipeline, and turn it into highly treated irrigation water. It’s expected to begin construction in early 2020 and come online in December, 2021.
“This will not only generate a new supply of water to farmers that is economically viable to them, but it also will save our wastewater customers an enormous amount of money,” said Director of Utilities, Christopher McKinney.
Escondido is outgrowing the pipeline it uses to discharge wastewater, he said, and needs to update its facilities. Replacing the line would cost at least $500 million dollars, he said, and there’s no assurance that the city could get environmental approvals it would need to do so.
“It runs along Escondido Creek, so from an environmental standpoint, it’s not really feasible to put in a bigger pipeline,” he said. “So the city did several studies on water recycling. Any water we recycle is water we don’t have to discharge.”
The City Council authorized the project in the spring, in an industrial area off of Washington Avenue. It recently selected a design/build team with the firms Filanc Construction and Brown and Caldwell to plan the facility and build the membrane filtration reverse osmosis plant. The city expects the plant itself to cost about $45 million, McKinney said, and the total project costs, including additional pipelines to distribute the recycled water, to be about $90 million.
Escondido treats about 12 million gallons of wastewater per day, and recycles about 4 million gallons, he said, but not all of that is suitable for agricultural use.
“It’s acceptable for irrigation, and is already used for parks, and industrial cooling,” he said. “The problem with using it for farming is, it’s too salty.”
Reverse osmosis units force the water through filters at high pressure to screen out salts and other solids, producing a purified product. That will help the city’s growers, particularly avocado farmers, who make up the bulk of their agricultural customers, and need water within specific salinity limits to grow their crops.
Avocados crops in Escondido generate about $40 million in revenue per year, according to the organization Escondido Growers for Agricultural Preservation. The fruit are highly sensitive to saline levels, according to the Avocado Growers Association, and elevated salt levels in irrigation water can dry out trees, inhibit growth, and reduce crop yield.
Farmers now use potable water for irrigation, but their supplies are subject to drought restrictions. By blending water treated through reverse osmosis with other, saltier recycled water, the city can produce a reliable supply of irrigation water that meets growers’ standards.
Recycling will reduce wastewater by 4 million to 6 million gallons per day, McKinney said, and also reduce the amount of imported water the city must buy.
A second phase of the project would expand the capacity of the plant, and also introduced advanced treatment processes that could clean the water to meet standards for indirect potable use. That means the water could be piped to reservoirs, and eventually to the city’s treatment plant, to augment Escondido’s drinking water supply.
Although earlier recycling facilities proposed in residential areas met opposition from neighbors, the city expects that the current site, in an industrial area, will not meet environmental obstacles.
“It’s broadly supported because on one hand it has the advantage of water recycling,” McKinney said. “Our farming community is excited to have a water supply that’s drought resistant.”