Rainbow MWD approves engineering studies, grant application for reclamation plant and recycled water distribution system

The Rainbow Municipal Water District approved detailed studies on a potential water reclamation plant and recycled water system while also approving the application of a water recycling planning grant.

One 4-1 Rainbow board vote Sept. 16, with Jack Griffiths in opposition, determined that the development of a local water reclamation plant and recycled water system has the potential to provide a drought-proof local supply of water for Rainbow ratepayers, determined that the development of a local water reclamation plant and recycled water system is potentially feasible but that additional information is needed.

The board also determined that should additional studies demonstrate the feasibility of a water reclamation plant and recycled water system, the board intends to pursue construction of the facilities necessary to operate such a system. It also determined that all work on the Beck Reservoir ultraviolet treatment project be stopped and that project placed on indefinite hold until the final decision on the development of a recycled water system is made.

With the Sept. 16 vote, the board authorized Rainbow general manager Tom Kennedy and Rainbow engineering manager Sherry Kirkpatrick to begin the process of preparing environmental review documents needed for California Environmental Quality Act compliance, authorized Kennedy and Kirkpatrick to apply for planning grants and other grants available for water reclamation projects from state and Federal sources, and appropriated $200,000 from Rainbow's master planning project for the cost to develop the pre-design report.

A second 4-1 vote that day, with Griffiths opposed, approved a resolution authorizing Kennedy to apply for the water recycling planning grant.

"The board took the first step towards creating a reliable drought-proof water supply," Kennedy said.

On Jan. 27, Rainbow's board awarded Atkins a consultant contract to update the district's water and wastewater master plans. The assessments included whether Rainbow should construct its own wastewater reclamation plant or continue conveying wastewater through the Oceanside Outfall. Atkins reviewed several locations for a water reclamation plant as well as methods of storing and distributing the recycled water.

Two potential projects were identified along with financial modeling for the costs of each project and the comparison of the cost to continuing to send wastewater to Oceanside including the purchase of additional capacity to meet future demand.

One option would construct a plant at or near the district headquarters site on Old Highway 395. That project would produce approximately 0.9 million gallons per day (mgd) of recycled water with perhaps an additional 0.2 mgd if the Warner Ranch project is approved while the remaining wastewater to the west of that site would continue to be conveyed to the San Luis Rey treatment plant operated by the City of Oceanside.

The other potential project would construct a plant near Lift Station 2 at the intersection of Old River Road and Gopher Canyon Road, which would produce about 1.6 mgd of recycled water and an additional 0.2 mgd if Warner Ranch is included while capturing more than 99 percent of all of the district's wastewater for re-use.

Although the potential 0.9 mgd project would have costs nearly identical to the "do nothing" alternative of sending wastewater through the Oceanside Outfall, the drought-proof water supply of more than 1,000 acre-feet per year would equate to approximately 7 percent of Rainbow's total supply and the production with the Warner Ranch project would be 1,232 acre-feet.

Although the 1.6 mgd option would have increased cost, it would produce nearly 1,800 acre-feet annually or more than 11 percent of the district's demands and that supply would increase to 2,016 acre-feet if Warner Ranch is built.

Rainbow's Beck Reservoir was constructed in 1983 and intended for fire suppression and emergency purposes and to improve water reliability for the Beck pressure zone. The earthen embankment reservoir has a capacity of approximately 204 million gallons.

Current U.S. Environmental Protection Agency surface water treatment regulations require that the reservoir either be covered or provide disinfection treatment, and Beck Reservoir was removed from service while the district conducted studies for the best long-term use.

The options included abandoning the reservoir while adding a second 6 million gallon tank to the existing Pala Mesa Tank, raw water storage, a floating cover, ultraviolet treatment, and recycled water storage. In 2013, the Rainbow board directed staff to move forward with the ultraviolet treatment option, which had an estimated $10.4 million cost.

The recycled water storage cost estimate of $15.1 million included pipelines and customer retrofits. In November 2013, the Rainbow board approved a $1.2 million consultant contract with Arcadis for permitting and design activities for an ultraviolet disinfection facility.

The master planning team evaluated the use of Beck Reservoir for potable water storage compared to recycled water storage. The storage capacity is not required for any potable water operational scenario, including emergency supply, so the most cost-effective use of the Beck Reservoir was determined to be recycled storage.

Beck Reservoir would be used as a wet weather storage pond and also for blending raw water with recycled water should agricultural demands exceed the amount of recycled water available.

The State Water Resources Control Board's water recycling funding program provides grants or low-interest loans to agencies pursuing various types of water projects. The planning grant is intended to assist agencies with completing planning studies for water recycling projects which use treated municipal wastewater and/or treated groundwater from sources contaminated by human activities.

Grants are provided for facilities planning studies to determine the feasibility of using recycled water to offset the use of potable state or local supply. The state grant would cover half of the eligible costs up to $75,000 of the water reclamation plant study.

"I think it's an important project. It's a big change for the district, but it's a change in the right direction," Kennedy said. "I think it's an exciting project. I think the long-term benefit for the ratepayers will be terrific."