AWWA ACE56139

Due to continued rapid growth, Gwinnett County, Georgia, is projected to experience peak daydemands in excess of their permitted 150-million gallons per day (mgd) treatment capacity overthe next several years. Although the county has begun construction of a plant which will providean additional 75-mgd of treatment capacity, it will not be completed until early 2004. This paper describes how the county, while facing thepossibility of being unable to meet peak water demands, developed a strategy forusing finished water storage for multi-day averaging of peak demands.Since a large number of Gwinnett County residents commute out of the county to work, peakdemands are typically seen during the weekends, and have historically been as high as 1.68 timesthe average annual day demand. An analysis was completed to determine the frequency anddistribution of peak days to decide if using dedicated storage for multi-day averaging of the peakdemands was a feasible alternative. The total storage needed to equalize demand for anticipatedperiods where demand exceeded available 150-mgd plant production was calculated. The analysisshowed that a volume of 40 million gallons (MG) of projected multi-day averaging storage(MDAS) would allow the county to meet anticipated peak demand periods until 2004.Two fast-track projects were undertaken in order to provide this reserve MDAS storage. The firstwas the construction of two 10-MG ground storage tanks and a booster station. A second projectinvolved the construction of a new 20-MG clearwell and a transfer pump station at the existingwater treatment plant.These two projects effectively increased the county's ability to meet an additional demandequivalent to 18-mgd above their current production through multi-day averaging of demandsduring peak demand periods. Using MDAS was found to be an economical option, with thecombined cost for these two projects at approximately $18 million. The additional effectivewater production capacity is provided at a cost of approximately $1.00 per gallon of equivalenttreatment capacity, which compares favorably to construction of additional water treatmentproduction capacity.Most importantly, since these smaller projects could be designed, permitted, and constructedmuch more rapidly than constructing additional treatment capacity, the county was able toimplement them much faster and continue to supply the rapidly growing county population. Includes 2 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/16/2002

Number of Pages:

10

File Size:

1 file , 450 KB