Home News Local, Drought-proof Drinking Supply On Its Way
By Roni Gehlke, Clean Water Magazine editor, Technology and Innovation
A purified water project that has been in the works for more than a decade, involving negotiations between four independent East San Diego County agencies and several local and state permitting organizations, is finally making progress toward completion and is expected to be operational by 2026.
The East County Advanced Water Purification Program (East County AWP) is a collaborative effort between Padre Dam Municipal Water District, the City of El Cajon, the County of San Diego, and Helix Water District.
“When completed, the potable reuse project will create a local, sustainable, and drought-proof drinking water supply, thereby reducing dependence on imported water,” said Seval Sen, East County AWP Engineering Manager.
The project is expected to process wastewater flows of approximately 15 mgd and produce, on average, 12,882 acre-feet per year, or 11.5 mgd, of safe, reliable, and locally controlled drinking water supply. The treated water will be mixed with imported and naturally occurring surface waters in Lake Jennings, withdrawn and treated at the R. M. Levy Water Treatment Plant, and then distributed as drinking water to customers in East County.
“One of the major concerns for much of Southern California is having a reliable and secure source of drinking water.” Mark Niemiec, Director of the East County AWP, stated that this region is no exception. “We live in a desert where water recycling is not a luxury but a necessity if we want to maintain stability in our communities and preserve our quality of life.”
Currently, the region imports a majority of its drinking water from Northern California and the Colorado River, which Niemiec said has been described as the hardest-working river in the West.
“We can do our part here by creating a local source of water,” he said.
PERMITS
In March, the State Water Resources Control Board’s Division of Drinking Water released their conditional acceptance letter for the Project’s Title 22 Engineering Report. This report outlines how treated and recycled water will be discharged and used in compliance with Title 22 of the California Code of Regulations. The project’s next step is to receive a National Pollutant Discharge Elimination System (NPDES) permit.
EVERYTHING NEW
According to Niemiec, the capital investment being made into the brand-new facilities and the treatment technology ensures East County AWP is implementing a redundant, robust, and resilient system that meets all regulations. The project will include a new water recycling facility, an advanced water purification facility, and a purified water pipeline transporting water 10 miles to Lake Jennings. There will also be new wastewater and residual pipelines, each segment being three miles long.
Additionally, a retrofitted pump station will be installed, and a City of San Diego partnership of regional brine and wastewater pipelines will travel from the pump station in Santee to the City of San Diego’s sewer line in Mission Valley. Furthermore, an energy recovery system will be created, producing up to three megawatts of renewable energy when implemented.
The new WRF will send flow to the AWP Facility for treatment through membrane filtration before Reverse Osmosis (RO). The RO system includes a primary and secondary RO, with ultraviolet light and an advanced oxidation process (UV/AOP) for further treatment. The UV/AOP effluent will be post-stabilized, and some will be diverted for dechlorination and aeration before being fed to Santee Lakes and Sycamore Creek. The rest of the flow will be injected with a boost dose of free chlorine before the AWP Facility product water pump station. Prior to entering Lake Jennings, the flow will be dechlorinated at a facility just upstream of the discharge location. Flow in Lake Jennings will receive 100:1 dilution aided by engineered mixing in the reservoir and then be blended with imported water supplies and treated at the R.M. Levy WTP prior to distribution.
DEMONSTRATION FACILITY
Sen said that East County AWP was fortunate to be able to build a 100,000 gallon/day demonstration facility to pilot how the new project would work. The facility, which was built in 2015, provided monitoring and testing during the two-year period. Monitoring included four quarterly samples that were taken at the secondary effluent, RO permeate, and advanced oxidation process effluent and tested for Contaminants of Emerging Concern. Also included in the monitoring program were almost 50 analytical methods that provided results for over 300 analytes.
In addition to the benefits of serving as a pilot program for the AWP, the Demonstration Facility also served as a significant public outreach tool. Niemiec said that tours provided at the Demonstration Facility were some of the most effective tools in the Communications Program and helped to transform perceptions about the project. Over 7,000 people had toured the Demonstration Facility before it was closed to begin construction of the new site.
“The tours gave the public the opportunity to see the treatment process and the purified water firsthand at the end of the process,” he said.
AWP CONSTRUCTION
Significant work has been completed on the East County AWP site since construction began in June 2022. Approximately 105,000 cubic yards of soil were imported for major earthwork activities, which have now been finished. Additionally, 60 percent of the concrete required for the project has been poured. The slab and the structural steel for the Visitor’s Center building, including a recently added roof, have been installed. Slabs have also been completed for three solids handling facility digesters and six water recycling facility aeration basins. Around 16,460 linear feet of 24-inch steel purified water pipeline have been installed, marking 33 percent completion. Approximately 7,200 linear feet of open-cut construction on the wastewater pipeline have been installed. Two areas of the project are still in the design phase and are making progress, including the regional brine and wastewater pipelines and the energy recovery system. The Program is scheduled to begin delivering water in 2026.
