ADRoP is a joint project between Sunnyslope Water, San Benito County Water District, the City of Hollister, and San Juan Bautista as part of the San Benito Urban Area Water Supply and Treatment Agreement. The project utilizes Aquifer Storage and Recovery (ASR) technology to improve the municipal and industrial (M&I) supply of high quality imported surface water. In wet years with excess water supply, some of the unused surface water will be treated and injected into the local aquifer for storage. During dry years with reduced surface water supply, that injected water can be drawn from the aquifer and delivered to customers.

SBCWD was awarded about $20 million in Federal and State grants for this project. The total cost is estimated at $50 million. SBCWD is fronting the cost and recovering it from Sunnyslope, Hollister, San Juan Bautista, and other M&I customers through a Water Reliability Fee charged on each acre-foot of water until the cost is paid.

The project construction is split into 3 separate phases:

Phase 1: West Hills Water Treatment Plant Expansion

The West Hills Water Treatment Plant must be expanded from 4.5 million gallons per day (MGD) capacity to 6.75 MGD. This allows for the treatment of the excess water during wet years. West Hills was originally designed to be expanded ultimately to 9.0 MGD so this is an intermediate step. 

Phase 2: Drilling Injection & Extraction Wells

Four wells are being drilled near Fallon Road on the north side of Hollister. This area has been determined to be ideal for ASR due to low groundwater movement and excellent groundwater quality. The wells are anticipated to have injection capacity of about 500gpm each and extraction capacity of about 1,000gpm each.

Phase 3: Pipeline to Wells & Well Site Improvements

Finally, a new pipeline must be installed in San Felipe Rd and Fallon Rd to connect the Hollister water distribution system to these new wells. A new chlorination building will be constructed to chlorinate water that is extracted from the wells prior to entering Hollister's water distribution system. Well site improvements will be done at each site for proper long-term operation of the wells.