San Diego Union Tribune 3/11/15
SANTEE — The Padre Dam Municipal Water District is getting ready to show off its Advanced Water Purification Demonstration Plant, which it hopes will provide East County with another source of potable water.
The project will take recycled water from the Ray Stoyer Water Recycling Facility and further treat it through advanced water purification technologies. The demonstration is scheduled to go through summer 2016. The water will be for testing only and won’t be added to the drinking water system. The project will not affect water rates, the district says.
The demonstration plant at the end of the chain of seven lakes will use four advanced water treatment steps: free chlorine disinfection, membrane filtration, reverse osmosis and ultraviolet/advanced oxidation to reuse wastewater.
After being treated, the water will be injected into a groundwater basin to be naturally filtered, then withdrawn and treated again before it would distributed as drinking water. The purified water will be tested daily to ensure it meets California Division of Drinking Water Department requirements.
The district is holding a grand opening of the plant at 10:30 a.m. April 10 at its site at 9390 Fanita Parkway. It broke ground on the project last October.
The project is being funded through a $3 million Proposition 50 grant from the Department of Water Resources.
Padre Dam GM Allen Carlisle says that if the demonstration project is a success and it moves forward, it would provide up to 2,000 to 3,000 acre-feet per year of drinking water — enough for close to 5,500 households and businesses. That’s nearly 15 percent of Padre Dam’s current drinking water demands.
Padre Dam imports all its drinking water from the Sacramento Bay Delta and the Colorado River.
“With the strains on California water resources and one of the most severe droughts we’ve ever experienced in the state, we really have no choice but to look at every option we have to find local source of water for our customers,” Carlisle said. “One of the drivers for Padre Dam is the fact that the Point Loma Water Treatment Plant is reaching the end of its permit, and an upgrade to that plant will come at great cost to ratepayers on the wastewater side.
“If we can find a way to eliminate the flow to Point Loma, and at the same time create a local supply, we really do have a win-win situation for our customers.”
The pilot demo plant will produce nearly 100,000 gallons of advanced treatment water per day for demonstration and testing.
An additional study is being conducted concurrently to consider the potential for expanding the program to include more East County communities. An expanded project would include the service areas of Padre Dam, Helix Water District, a portion of the county of San Diego and the city of El Cajon.
The district and an independent oversight committee will monitor the water for a year, but Carlisle said he is confident that the technology being used is “more than sufficient to take this recycled water to next level.”
Eventually the project could be similar to the successful groundwater replenishment system in Orange County, which has been operating since January 2008. It can produce up to 70 million gallons of water every day, enough water to meet the needs of nearly 600,000 residents in the area.
San Diego city is also testing a system that would purify wastewater to the level that it is potable. Its Pure Water project involves several stages of treatment. Micro-filters would remove solids from wastewater, then reverse osmosis would filter out organic materials and salts. Finally, ultraviolet light and hydrogen peroxide would eliminate remaining contaminants.
San Diego envisions producing 83 million gallons per day by 2035 — about a third of the city’s overall supply of potable water.
Padre Dam provides water, wastewater, recycled water and recreation services to nearly 100,000 residents in Santee, El Cajon, Lakeside, Flinn Springs, Harbison Canyon, Blossom Valley, Alpine, Dehesa and Crest.
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