AWWA MTC69730

The Yucaipa Valley Regional Water Filtration Facility (YVRWFF), which is a 12 MGD potable water filtration facility, has been treating surface water since the June 29, 2007. The primary feed water source is State Project Water with alternative sources from Mill Creek and the Santa Ana River. Water flows from the Crafton Hills Reservoir into the Free Surface Structure. The raw feed water is first fed through two 400 micron automatic back-washable strainers before reaching the free surface structure. From the free surface structure the feed water flows by gravity through manual basket strainers to the microfiltration system. The basket strainers are sized to remove anything greater than 400 micron that may have accumulated in the free surface structure. The strained water is fed directly to the five microfiltration (MF) units to produce filtered water. The microfiltration units operate automatically and adjust to incoming feed flow rates based on the level of the free surface structure and incoming water flow. The filtration performance is measured by the turbidity of the filtered water (filtrate). Each unit is equipped with an individual turbidity analyzer to monitor the filter performance. Seventy-five percent of the MF treated water is further filtered with nanofiltration (NF) membranes to remove organic constituents that can form disinfection byproducts when combined with chlorine. The NF water is blended with the remaining MF water to make up the plant filtrate water. The plant filtrate is dosed with 3.5 mg/L sodium hypochlorite for primary and secondary disinfection and 1 ppm corrosion inhibitor to prevent corrosion of the distribution piping. The facility also has the ability to dose 25% sodium hydroxide for final pH adjustment; however, this has been limited since the plant filtrate pH has ranged from 7.7-8.3 since start-up. Before being delivered to the District, the plant filtrate enters a 6 MG finished reservoir for primary disinfection contact time. The District has installed 6 MGD of NF based upon the current demand of 8 MGD. The finished product water consists of a blend of approximately 6 MGD of NF permeate and 2 MGD of MF filtrate. At this time, the production level of the facility is such that 8 mgd is the targeted capacity with the 75:25 blending ratio. Includes tables, figures.