Resilient Supply, Sustainable Solution

The primary water supply for the Central Coast region of California is groundwater. That’s especially true for the Soquel Creek Water District, whose service area reaches from the Pacific Ocean to the Santa Cruz Mountains about halfway between San Francisco and Monterey. The district’s sole source of water is the Santa Cruz Mid-County Groundwater Basin. At issue: the 36,920-acre foot basin is critically over-drafted according to the State of California and threatened by irreversible contamination from seawater infiltration.

Needing to meet a state-mandated groundwater sustainability plan by 2040 and facing an estimated 30-year supply deficit in the basin, the district developed its Pure Water Soquel Treatment Facilities Project under a progressive design-build agreement with Black & Veatch. The purpose of the over-arching Pure Water Soquel Program, which launched in 2015 and is expected to be operational in 2024, is akin to that of Pure Water San Diego and Orange County’s Groundwater Replenishment System in California. It’s to recharge the Santa Cruz Mid-County Basin with purified reused water from the City of Santa Cruz Wastewater Treatment Facility (WWTF).

The Monterey Bay National Marine Sanctuary is renowned for its spectacular views and diverse wildlife. The regional practice has been to discharge treated wastewater into the federally protected sanctuary offshore. Under Pure Water Soquel, the district will purify already treated wastewater using advanced technologies then pump it underground to replenish the basin, restore its barrier against seawater intrusion, and reduce discharges into the sanctuary.

Specifically, the project will reclaim and reuse approximately 25 percent of the secondary effluent at Santa Cruz Wastewater Treatment Facility and pipe it to a new Advanced Water Purification Center (AWPC) designed and built by Black & Veatch. Providing ozone pretreatment, microfiltration, reverse osmosis, UV disinfection with advanced oxidation, and post-treatment processes, the AWPC will produce water purer than bottled water. The Pure Water Soquel Program also includes a new 8-mile pipeline and pump station system that will move the water between the Santa Cruz WWTF, the AWPC, and three new wells where the purified water will be replenished into the basin.

Up to 1,500 acre-feet of purified reused water will be produced annually for groundwater replenishment and seawater intrusion prevention. An additional 300 acre-feet per year of Title 22 unrestricted, non-potable recycled water will be produced for in-plant use and irrigation and construction purposes at the Santa Cruz WWTF – in effect increasing the potable water available to the community.

The AWPC is also designed with features that address aesthetic, noise, and other concerns expressed by the surrounding community and Santa Cruz County residents through an extensive public outreach and education effort by the district. The complex treatment facilities are designed to be mostly unseen to the public eye with architectural screenings that showcase the local marine life. The conveyance and wells components of the program are built underground to recharge and protect the complex underground basin.

The sustainable, community-based approach of Pure Water Soquel shows the value communities can realize adopting reuse. That reusing the water they have, they can promote environmental stewardship, support a thriving community, and be resilient to climate change.