Carpinteria Valley Water District has long pondered the possibility of tapping treated wastewater as a source to protect the local water supply from the depletion of cyclical droughts.
To this end, CVWD General Manager Bob McDonald said that it’s likely the water board will vote on whether to proceed with conducting environmental studies on a project that would take wastewater treated at Carpinteria Sanitary District and pump it into the Carpinteria Valley groundwater basin.
The recycled wastewater plan, which was first reviewed by the City of Carpinteria, Carpinteria Sanitary District and CVWD in a 2016 report, would be expensive to execute, but proponents argue that it is a necessary, safe and reliable way to fend off water insecurity.
CVWD boardmembers gathered on May 30 for the second installment in a series of workshops designed to inform their decision making ahead of possibly initiating the project. There’s a lot to know about the project from advanced wastewater treatment to mapping the flow of water underground and water rights for the new supply.
McDonald said the board appears prepared for a vote on whether to allot up to $1 million on the environmental study that needs to be conducted before the project could be constructed.
CVWD would have to fund an Environmental Impact Report, but likely after the study is underway it could recoup some of those costs along with greater funds for the project that is estimated to cost around $21 million to construct and $1 million annually to operate. McDonald said that funding sources from the state are available, but projects need to be more shovel ready before they qualify.
The city and sanitary district joined the water district in commissioning the initial studies that showed a recycled water project could be feasible in Carpinteria. Both the sanitary district and city have passed resolutions supporting the water district should it wish to proceed with the project.
The city is more of a peripheral onlooker and permitting agency, while the sanitary district would have to upgrade its wastewater treatment plant to meet standards for reinjecting the water into the basin. CVWD would be the lead agency and owner of the new water supply.
CSD General Manager Craig Murray said after the wastewater undergoes reverse osmosis and UV treatment, it’s potable directly out of the plant. Currently, CSD conducts tertiary treatment and discharges treated water offshore from Carpinteria State Beach.
The recycling plan calls for a pipeline leaving the CSD treatment plant to be installed heading inland toward the mountains to reach an optimal location for injection into the groundwater basin. Preliminary findings identified sites at St. Joseph’s Church and Franklin Park on Sterling Avenue as ideal places for injection wells.
From those injection points, the recycled water would sit in the groundwater basin for six months after being treated before reaching either a CVWD or private well. CVWD has not secured permission to build the injection wells at those sites.
The six month buffer between injection and availability to taps would allow water to further dilute underground and meet state requirements designed to prevent contaminated water from reaching public water lines. If a glitch was detected at the treatment plant and contaminated water made it into injection wells, the six month window would provide a response time for the utilities to remedy issues.
Studies show that the new system could supply about 1,200 acre-feet annually to the groundwater supply, which would offset the district’s current consumption of about 4,000 acre-feet. The groundwater supply has suffered under recent drought conditions both from elevated consumption and diminished natural recharge.
In addition to drought jeopardizing water supplies, the diminished groundwater basin is vulnerable to salt water intrusion. Injecting recycled wastewater could mitigate the potential of salt water intrusion by increasing water volume and pressure within the basin and acting as a natural barrier to sea water.
Public concern over the safety of using treated wastewater in the drinking water supply has historically arisen when new systems are proposed. Both McDonald and Murray said that these systems are nothing new and state regulations are very tight when it comes to constructing and executing such projects.
Orange County has had its recycled water system in place for a decade with no contamination issues.
At the May 30 workshop, Mike MCullough of Pure Water Monterey presented on the extensive recycled water project that is underway in Monterey. Supply issues there led to a comprehensive plan to collect multiple sources of wastewater and inject it into the basin.
McDonald said that the expense of a new water supply is worth it considering the unreliability of the state water project. Already the State Water Resources Board has informed districts to only expect around 70 percent of the water that should be delivered under the state water project.
Most supplies outside of local groundwater are subject to cooperative agreements with other districts. Recharging the local groundwater basin guarantees a privately owned source and greater water independence.