Montevina Water Treatment Plant Improvements

San Jose Water Company (SJWC) selected us to design and build major improvements to their 43-year-old Montevina Water Treatment Plant (WTP).

The Montevina WTP is the primary water supply source for the Town of Los Gatos and surrounding west Silicon Valley communities. It treats surface water collected in the Santa Cruz Mountains watershed. Upgrades enable SJWC to treat water with raw water turbidity levels as high as 100 to 500 Nephelometric Turbidity Units (NTU) during and following storm events, and allow them to continue delivering high quality drinking water to customers, increase the reliability of plant facilities, and reduce the need for more expensive imported water from other utilities.

The scope involved converting the existing 30 MGD plant from direct filtration to a membrane filtration facility. Elements included an improved flash mix and flocculation process followed by settling basins and a membrane filtration system, and improved solids handling facilities with clarifier thickeners and screw presses for managing residuals. It also encompassed construction of a new administration building, water quality laboratory, standby power generation and site access improvements.

Elements to success included innovative treatment process ideas, such as an energy efficient pump flash mix and hydraulic flocculation systems, conversion of the existing filters to pre-treatment basins, cost effective solids handing upgrades, and nanofiltration of membrane CIP waste to minimize waste export from the site. Sequencing and staging kept the plant in production throughout construction and was a critical element to maintain trade productivity and site safety. Selection of a membrane supplier and completion of a successful proof of performance test were critical. Identification and development of a second plant entrance reduced safety risks and improved plant traffic flow.

The project started in 2014 and was completed in 2017. The progressive design-build approach met SJWC’s expectations in terms of innovation, collaboration, and flexibility to adjust the scope of the project to meet a fixed budget. We worked together during the design phase to incorporate several innovative ideas into the project.