Project Summary

The Crosstown Pipeline Project installed approximately 2.5 miles of large (16"-20" diameter) water transmission pipeline, a new booster pump station, and blending stations at multiple well sites. Accomplishing this project required close coordination between Sunnyslope County Water District, the City of Hollister, San Benito County, and San Benito School District. Such interagency cooperation showcased the importance of partnerships within the community to minimize costs and maximize the public benefit. With the completion of this project, high quality treated surface water from the West Hills Water Treatment Plant can be delivered for blending at each of the City of Hollister's well sites as well as two primary Sunnyslope well sites. Thus all customers within the Hollister area can receive the benefits of this high quality water.

Background

The Crosstown Pipeline Project was identified as a regional need in the Hollister Urban Area Water & Wastewater Master Plan. A large capacity water transmission pipeline is necessary to move treated surface water from the West Hills plant especially into Sunnyslope's water system. When a Maximum Contaminant Level for Chromium VI (Cr VI) of 10ppb was instituted by the California Division of Drinking Water, the City of Hollister learned that all of its potable water supply wells exceeded this limit. To address this issue, the City got approval to blend its well water with West Hills water to reduce the Cr VI concentration below the regulatory limit. Thus, West Hills water needed to be delivered directly to each well for blending before entering the water distribution system.

Design

After issuing Requests for Proposal for the project design and evaluating the submitted proposals, Kennedy/Jenks Consultants was selected to design the project. The opportunity to incorporate the new pipeline into the design and construction of San Benito County's River Parkway Project arose early in the process due to the fortunate timing of the two projects. To accommodate the schedule of the River Parkway Project, the Crosstown Pipeline was divided into two separate phases.

Because the elevation of the Sunnyslope water system is higher than that of the West Hills plant, a booster pump station was required to move water to Sunnyslope. Existing District property near Southside Elementary School was able to be utilized for this booster station to reduce costs. A building to house the pumps and controls was designed.

Special care was given to the design of the multiple pipeline crossings over the Calaveras Fault to ensure that the pipeline would remain operational after a major earthquake. 

Construction

The first phase of the project was awarded to the Don Chapin Co. as part of the larger River Parkway Project by San Benito County. They installed approximately 3,600 linear feet of 20" PVC pipe with the construction of River Parkway Dr. Combining these two projects ultimately reduced the cost for each.

The second phase of the project was awarded to Specialty Construction Inc. This phase included the installation of approximately 1 mile of 18" pipe and 0.8 miles of 16" pipe in existing roadways. Improvements at the City of Hollister's Bundeson Well 2 were done to allow for the precise blending between water from West Hills and water from that well.

A 2,800gpm booster pump station was constructed at Sunnyslope's Well 2 property. This included the construction of the booster pump building, chlorine room, blending station, and surge tank. Piping was also installed to blend West Hills water with Sunnyslope's Well 2 and Well 11.

Remote monitoring and controls for the pump station and blending stations were programmed so operators could make any adjustments needed without being onsite. 

Project Cost

 The entire Crosstown Pipeline Project had a final cost of $7,214,706. This includes all the costs for the initial project planning, environmental analysis, engineering & design, bidding, the construction contract, change orders, construction management, and other project-related expenses.

Sunnyslope's portion of this cost was $5,198,199 while the City of Hollister's portion was $2,025,507. No loans or other financing methods were taken out to pay for this project as both agencies had adequately planned and budgeted for these expenses. Such long-term planning saved the significant interest and financing costs.