West Hills Water Treatment Plant


The West Hills Water Treatment Plant was a new plant that was completed in the fall of 2017. This new plant has the capacity to treat 4.5 million gallons of surface water daily. The treated water is then blended with well water, resulting in less salt in the water and a reduction of hexavalent chromium contamination improving the quality of water that customers will receive.

These upgrades to the water system have also improved the quality of wastewater discharge and allowed for state regulations to be met, thereby avoiding costly fines. There was also a strong desire to fully automate the water treatment process to protect district employees.


The San Benito Water District delivers drinking to the Sunnyslope County Water District and the city of Hollister. Located in the central Valley of California, there are over 35,000 people who live in Hollister and the surrounding area.


PRIMEX worked closely with the general contractor, Auburn Constructors in the design, construction and programming of the wastewater treatment plant. PRIMEX served as the overall system integrator for the project. The original scope included engineering, design, manufacturing and startup of the raw water pump station that delivered water from the nearby reservoirs to the plant for treatment as well as development of the plant’s Wonderware SCADA and Win-911 alarm notification systems that allowed operators to control every aspect of the plant including the 5 vendor-supplied systems. PRIMEX installed the PLC’s, the water pump station Touch Screen Panel as well as providing, installing, configuring, and programming Wonderware Runtime & Development Studio, Tier-1 & Tier-2 Historian, Dream Report, & Win-911.

When the project was approaching 80% completion, it was recognized that one of the specific construction goals, that the plant be fully automated, was not going to be met. PRIMEX led the coordination between all the vendors, subs and the general contractor to revise the software throughout the project, transforming the plant from manual control requiring constant operator intervention at every level to fully automated with integrated startup and shutdown sequences across the entire plant.

As part of the complete integration services provided, PRIMEX was tasked with system documentation which included designing and drafting loop and interconnection diagrams.


PRIMEX programming staff are trained to program a vast array of different software programs, providing better, faster service to our customers. Coupled with the intimate knowledge of the plant operation gained during the advanced integration, this has allowed on-going, advanced support during troubleshooting and maintenance long after the plant commenced full operation.

Sunnyslope County Water District
Jim Fillice

September 2015 – October 2017


John West, Project Manager
Auburn Construction


  • Project Management
  • Engineering
  • Programming Programmable Logic Controllers
  • Network configuration services
  • Field Testing
  • Operator training
  • Commissioning