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Resource Issues: Desalination and Water Supply Project Details
Pure Water Monterey- #MBNMS-2018-042

Project Description

Monterey One Water (M1W) is undertaking the Pure Water Monterey (PWM) Project in partnership with the Monterey Peninsula Water Management District (MPWMD). The PWM Project includes an Advanced Water Purification Facility (AWPF) consisting of a four-step process that would further treat water that has already been treated by the existing primary and secondary treatment processes at the treatment plant:

  1. Ozone (O3) Pre-Treatment
  2. Membrane Filtration (MF)
  3. Reverse Osmosis (RO)
  4. Advanced Oxidation with Ultra Violet Light (UV) and Hydrogen Peroxide (H2O2)

The PWM Project also includes product water conveyance pipelines, pump station, and injection well facilities. The PWM Project is located in unincorporated areas of the Salinas Valley in Monterey County, and within the cities of Salinas, Marina, and Seaside. The PWM Project would obtain new raw waters (agricultural wash water, urban storm water runoff, and surface waters) and combine them with existing wastewater inflow to the Treatment Plant to receive primary and secondary treatment before beneficial reuse at either the Salinas Valley Reclamation Plant (SVRP) or by the PWM Project AWPF. Secondary-treated effluent not treated to tertiary levels at Salinas Valley Reclamation Plant for distribution for agricultural irrigation would be conveyed to the AWPF. The advanced purified recycled water produced at the AWPF would meet or exceed federal and state drinking water standards, including Title 22 of the California Code of Regulations and its requirements for groundwater replenishment with recycled water.

The Seaside Groundwater Basin would be replenished by injecting purified recycled water into both shallow and deep injection wells where it would mix with native groundwater, be stored, and subsequently, be available for extraction by CalAm. This water source would replace water derived from the Carmel River alluvial aquifer. Customers in the Marina Coast Water District system would use up to 600 AFY of purified water for urban landscape irrigation. The PWM Project would enhance water supplies from the existing tertiary treatment plant for agricultural irrigation in the northern portion of the Salinas Valley, enabling a reduction in groundwater pumping whereby slowing seawater intrusion. On-site operations would generate RO concentrate that M1W proposes to discharge to the ocean using their existing ocean outfall blended with secondary effluent and small truckloads of brine when available.

The PWM Project is designed to create a reliable supply of water for northern Monterey County by replenishing the Seaside Groundwater Basin with 3,500 Acre Feet per Year (AFY) of purified recycled water. This would replace a portion of CalAm’s water supply as required by State Water Resources Control Board (State Water Board) orders and provide up to 600 AFY of purified recycled water to Marina Coast Water District (MCWD) for urban landscape irrigation.