Workers in Orange County, California, are installing new distribution piping to deliver recycled water to area homeowners’ associations. The El Toro Water District, a pioneer in water reuse in 1963, is undertaking a $37-million project to dramatically increase its capacity to supply recycled water for irrigation. Courtesy of MWH Constructors, Inc.
The El Toro Water District, in Orange County, California, is significantly expanding its recycled water program to reduce its dependence on imported water.
May 14, 2013—Work is under way on a $37-million project that will greatly increase the capacity of the El Toro Water District, in Orange County, California, to treat and recycle effluent for irrigation. The district currently imports 95 percent of the water used by the approximately 51,000 customers it serves.
This imported water is sourced from the Colorado River and from the delta formed by the confluence of the Sacramento and San Joaquin rivers, and these sources are already heavily stressed. What is more, the Colorado’s flow is projected by global warming models to fall by as much as 20 percent over the next 40 years.
The El Toro Water District has been a pioneer in recycled water, having built an advanced treatment facility in 1963. That system currently recycles approximately 500 acre-ft of water per year, subjecting it to secondary treatment and chlorine disinfection. By far the largest portion of the water goes to a local golf course for irrigation.
But the district estimates that in the future the demand for recycled water will far outstrip the supply during the hot, dry summer months. The current project will nearly triple the capacity of the plant, increasing the volume of water treated to 1,400 acre-ft per year. This will lower the need to import water, reduce the amount of potable water used for irrigation, and cut the discharge of effluent into the Pacific Ocean.
“This is the largest project the district has done in quite some time,” says Andrea Carlson, an engineer with MWH Constructors, which is headquartered in Broomfield, Colorado. MWH is providing construction management services for the project, and it has deployed a staff of resident engineers, construction managers, and inspectors.
The plant expansion will also improve the treatment process, adding a tertiary system of cloth media disk filters to meet the stringent requirements for recycled water set forth in title 22 of the California Code of Regulations. This tertiary treatment will enable the water district to provide recycled water to a wider range of commercial and public customers. The tertiary filters are being supplied by Aqua-Aerobic Systems, Inc., of Loves Park, Illinois.
“Aqua-Aerobic performed a pilot test at the plant, and the district was very happy with how [the filters] performed,” Carlson says. “They are relatively easy to clean and to install.”
A new, 2.4 million gal storage tank with internal baffles will serve as the system’s chlorine contact basin, providing disinfection as well as storage for the recycled water.
The treated water will then enter three new pipelines, which will have a total length of approximately 19 mi. The project includes a new pump station with two operating, or duty, pumps and one standby pump. The duty pumps are 250 hp units rated at 1,900 gpm. The standby pump is 125 hp and is rated at 800 gpm.
Pipelines of varying lengths extend from the plant to the north, east, and west. The lines will serve the irrigation needs of homeowners’ associations for large, gated retirement communities in Laguna Hills and Laguna Woods.
The gated communities present several challenges for the project. Residents will need to accept and comply with traffic control measures in the early phases of the pipeline construction, which will see large distribution mains, some with diameters of as much as 20 in., installed via cut-and-cover methods along city streets.
“Because you are in this gated community with relatively narrow streets, at the end of the day the contractor is not allowed to stockpile any material, leave any equipment, [or] leave any piping against the curb,” Carlson says. “The contractor literally has to haul in his equipment and materials on a daily basis and then haul them out at the end of the day. You don’t really get an eight-hour day of production.”
To better inform the public about the project, the team has developed a website that enables a resident to enter his or her address and access a map that represents a color-coded version of the contractor’s schedule for the next two weeks.
“We found this is helpful in letting the public know what to expect,” Carlson says. Daily email reports to local emergency responders detail the activity areas and the possible road closures of the day.
“From what I’m hearing from fire service here, [nearby] Station 22 is the second-busiest in the county,” Carlson says. “When people are calling 911, we don’t want to be the cause of seconds or minutes being lost because of construction in the roadway.”
All phases of the project are slated for completion by the end of 2014.