Irvine Ranch Water District’s Deep Aquifer Treatment System (DATS) purifies drinking water from the lower aquifer of the Orange County Groundwater Basin. An aquifer is an underground area which stores water naturally. Although the water from this aquifer is very high in quality, it was previously been unusable because it has a brownish tint imparted from the remains of ancient vegetation that once populated the area. However, new purification technologies now make it possible and cost-effective to remove the color from this water. The DATS facility went on-line in early 2002.

The facility includes two wells that pump water from approximately 2000 ft. below ground level. This colored water enters the treatment plant and travels through tightly-wound membranes. Because the color molecules are much larger than the water molecules, they can readily be filtered out.  After undergoing this “nano-filtration” treatment, the water is clear. It then travels through degasifiers that remove low levels of methane gas that would otherwise give the water a “fizzy” appearance.

Following treatment at the DATS facility, the water travels through pipelines with water from other wells and is then disinfected before it enters the IRWD distribution system. The color molecules that are filtered out are referred to as concentrate, which is discharged into the sanitary sewer system.  The treatment process has a 92% efficiency rate. In other words, for every 100 gallons of colored water that passes through the facility, 92 gallons of clear water are produced and only 8 gallons of concentrate must be disposed.  An engineering team is currently working on system upgrades that may be able to increase the efficiency as high as 98%. The DATS facility can treat up to 7.4 million gallons of water per day.

This project benefits all groundwater users in northern and central Orange County because it helps prevent wells from being affected by seepage of colored water into the middle aquifer used for drinking water by many cities and water districts.

Deep Aquifer Treatment System brochure available.

San Joaquin Reservoir was built in 1966 and was originally used as a drinking water reservoir by seven cities and water districts. However, after the enactment of more stringent water quality regulations that prohibited storage of drinking water in an open reservoir, the facility was drained and sat empty from 1994 until 2005.

After drainage of the facility, the neighbors expressed a desire to restore a water view and in 2001, Irvine Ranch Water District proposed purchasing the reservoir from the joint owners and converting the reservoir to store recycled water. Because recycled water is used for irrigation and not for drinking, it can be safely stored in an open reservoir without a cover. Work to convert the reservoir began in 2004 and took approximately one year to complete. Water began flowing into the new recycled water reservoir in December 2004 and its re-dedication ceremony was held in February 2005.

This recycled water reservoir provides 3,080 acre-feet (nearly one billion gallons) of seasonal storage for recycled water. Operation of the reservoir maximizes storage during the winter months when irrigation demands are lower. Water is then withdrawn from the reservoir in the summer months to provide landscape irrigation water for Irvine, Newport Coast and portions of the city of Newport Beach.

The Irvine Desalter Project purifies water found in the Irvine sub-basin of the larger Orange County groundwater basin. It is a two-part endeavor, with non-potable (recycled water) and potable (drinking water) components.

Irvine Ranch Water District took the lead on the Irvine Desalter Project, a complex endeavor
that required unprecedented cooperation among federal, state and local agencies. The site map
below depicts both the Potable and Non-Potable components of the project. Treated water
from within the plume of contamination from the former military base is not used for drinking
or other household purposes.

Part one: Non-potable component

This key project removes a volatile organic compound called trichloroethylene --TCE-- found in 1985 to be polluting groundwater in the area beneath the former El Toro Marine Base. TCE was a solvent used to degrease airplane parts. Groundwater monitoring showed that a “plume” of TCE-tainted groundwater was moving off of the base and toward the main groundwater basin that supplies water for central and northern Orange County.

To clean the TCE-contaminated groundwater, water from the plume is pumped from wells on the former base and in the community and piped to two purification plants (shown as purple squares on the site map below right). There it is treated using air strippers to separate the chemical from the water, and the TCE is captured on granular activated carbon filters so that no air pollution is created. The cleaned water is then used in the recycled water system for landscape irrigation and other non-drinking water purposes.

Shallow Groundwater Unit Facility, located just outside former
El Toro Marine Base.
Air Stripping Tower: The TCE contaminant is separated from
the water in this 50-foot tower, where it returns to a gaseous
state and is captured on two granular activated carbon filters.
The filtered water is used for irrigation and other non-drinking
water purposes.

Part two: Potable component

Due to natural geology in the area, the groundwater beneath Irvine is higher in salts. This water is pumped from wells located safely outside the area of the TCE contamination. The water is treated separately at a plant using reverse osmosis, decarbonation and disinfection. The resulting purified water supplies enough drinking water each year for about 50,000 people.

Reverse Osmosis: The heart of the Irvine Desalter Potable Treatment Facility consists of two reverse osmosis trains. These are used to separate the salt from the water. A total of 434 reverse osmosis membrane elements are inside the 62 pressure vessels. Two 300 horsepower pumps pressurize the water for the membrane separation process. The two trains combined produce 2.7 million gallons per day of desalted water.

Decarbonation: High quality water from the reverse osmosis process is further treated using a forced air decarbonator. The decarbonation removes carbon dioxide from the water prior to blending this with local well water. Three-inch diameter plastic media are loaded inside the decarbonator to aid in the removal of carbon dioxide gas. A 7.5 horsepower fan blows air through the water, removing carbon dioxide in the process.

The drinking water plant uses reverse osmosis membranes to separate salt from water. A total of 434 reverse osmosis membranes elements are inside 62 pressure vessels.

Irvine Desalter Project brochure