Todd Engineers has had the opportunity to work with San Benito County Water District (SBCWD) on a number of groundwater management projects. The SBCWD is a wholesaler of imported water for San Benito County, providing raw water to irrigation customers through an extensive network of pipelines. The SBCWD also provides management for the groundwater basin, working cooperatively with San Benito County and local water supply and wastewater agencies as a member of the Water Resources Association of San Benito County (WRA).

Groundwater Management Plan Update

In 2000, the WRA embarked on an update of their groundwater management plan and retained Todd Engineers, in association with EDAW, to assist with plan development. Todd Engineers conducted an evaluation of the basin hydrogeology and changes in groundwater storage due to decades of artificial recharge. We examined the basin water balance with and without the importation of surface water, results of which are summarized on the chart shown to the right.

In developing the plan, Todd Engineers, along with the WRA, took a comprehensive basin-wide approach that considered the full spectrum of basin management objectives of water levels and water quality. Kennedy/Jenks is continuing the planning effort with the WRA by working with WRA members to synthesize and prioritize the 36 programs/projects alternatives for groundwater management such as recycled water, groundwater distribution pipeline, constructed wetlands, water filtration/demineralization, water conservation, water banking.

Analysis that Kennedy/Jenks has performed for the update included development of municipal and industrial water demand projections, preparation of groundwater balance under various water supply alternatives, and qualitative and quantitative evaluation of various combinations of water resources (imported and local surface water, groundwater, and recycled water) to meet future demands. The update also included prioritization of programs/projects and preparation of planning-level estimates of probable costs of construction.

Kennedy/Jenks staff also organized and presented results of the Groundwater Management Plan Update at two public meetings. As the groundwater management plan moves into environmental assessment prior to implementation, Kennedy/Jenks continues to support the preparation of Programmatic Environmental Impact Report for the Groundwater Management Plan Update with water quality evaluations and water demand projects.

Conjunctive Use

As part of its groundwater management activities, the SBCWD releases imported water and stored local surface water to the San Benito River channel for artificial recharge as shown in the photograph on the next page. Seeking to improve conjunctive use of its groundwater and imported water supplies, the SBCWD is considering a well field along the river to recover a portion of its artificially recharged water. Todd Engineers provided an initial assessment of the technical and regulatory feasibility of constructing and operating this well field. Recommendations for exploratory drilling and additional investigations were summarized in a technical memorandum.

In late 2002, Todd Engineers directed installation, logging, and testing of a test well at the site. Todd Engineers also is evaluating a private well for possible acquisition by the SBCWD, to enhance flexibility in providing water supply and managing groundwater levels. Todd Engineers coordinated video logging of the well, performed a pumping test, and conducted water quality sampling. The results of the evaluation are promising and currently are being documented in technical memorandum.

Water Quality Study

Todd Engineers recognized during the groundwater planning process that the SBCWD required additional data on groundwater quality to make informed management decisions such as the location of recharge structures and groundwater extraction areas. To fill this gap, Todd Engineers asked and received the SBCWD's permission to apply for an AB303 grant on their behalf to fund a water quality assessment and a water quality monitoring program. The grant was awarded to the SBCWD, and Todd Engineers began the project in November 2002. Kennedy/Jenks is also working on the basin water quality issues with the feasibility analysis of various demineralization and desalting methods to reduce hardness and TDS for the Sunnyslope County Water District, a member of the WRA.