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JAN-FEB 2019

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36 INTECH JANUARY/FEBRUARY 2019 WWW.ISA.ORG FAST FORWARD l An online water quality and control system is an effective way to monitor and control water quality. l SCADA system reliability is key to online data collection and calculations. l The online water quality and control system conforms to EPA water quality surveillance and response system guidelines. By Diep Nguyen, PE, Jeff Gilman, PE, Todd Reynolds, PE, and A.J. Cottengim T he San Francisco Public Utilities Commis- sion (SFPUC), the municipal water supply agency for the city and county of San Fran - cisco, Calif., began mixing groundwater from a local aquifer with the city's customary surface- water supply sources in April 2017. San Francisco had not used groundwater as a drinking water supply for more than 90 years. The planning, engineering design, and construction for this re newed groundwater use was accomplished under the San Francisco Groundwater Supply P roject (SFGW Project), a part of the agency's cap- ital program to diversify the city's drinking water supply sources and increase their reliability. Due to differences in water quality between the groundwater and surface water, the SFGW Project opted to blend groundwater in small quantities with the surface-water supplies in two city reservoirs. This blending or mixing allows the city to continue to surpass all regu - latory drinking water standards, as well as to ensure that changes in taste or odor are not noticed. A specialized project team developed and executed an online monitoring and con - trol system to satisfy the project's water quality requirements. The team includes SFPUC proj - ect management staff. The team members for the water quality control system included per - sonnel from DTN Engineers, Kennedy/Jenks Consultants, and Tesco Controls. Background SFPUC is a purveyor to water retail custom- ers in the city and county of San Francisco, as well as to 26 wholesale cus tomers that serve Al- ameda, San Mateo, and Santa Clara counties in the greater Bay Area. From the mid-1930s until recently, SFPUC's municipal supply came from the Hetch Hetchy Regional Water Sys- tem, a system that combines the surface-water re sources of the Hetch Hetchy Reservoir in the Sierra Nevada mountain range with five reser- voirs in the Bay Area. On average, 85 percent of SFPUC's water has been supplied by the Hetch Hetchy Reservoir, and the five Bay Area reser- voirs have provided the remaining 15 percent. Beginning in the mid-2000s, SFPUC em- barked on the Water System Improvement Pro- gram (WSIP), a $4.8-billion-dollar, multiyear capital program to upgrade SFPUC's regional Effective method to monitor and control water quality to blend groundwater in small quantities with the surface-water supplies and conform to all regulatory drinking water standards Online water quality and control system

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