SLOW SAND FILTERS FOR A SMALL WATER-SYSTEM

Slow sand filtration was selected to meet the Surface Water Treatment Rule requirements for the community of Camptonville, Calif. The slow s and filtration facility uses precast concrete vaults, hauled by truck to the site and laid out in a linear arrangement to adjust to the cont our of the steep hillside site. This alternative filtration process is credited by the California Department of Health Services with 2-log G iardia and 1-log virus reduction. A 3-log Giardia and 4-log virus remo val can be achieved with disinfection. The facility began operation in December 1991 and has maintained a treated water turbidity <1.0 ntu, despite stream turbidities of >30 ntu. The process effectively removes high levels of iron and manganese from the community's backup groundw ater supply. In addition, low construction and operating and maintenan ce costs have kept customers' costs down.