Full Description

The Central Wyoming Regional Water System operates 29 groundwatercollection devices in an alluvial aquifer adjacent to the North Platte River. Thesecollection devices were previously designated as being "ground water under the directinfluence of surface water" (GWUDISW). In lieu of constructing a conventional surfacewater treatment plant the utility opted to perform a two-year study to demonstrate thatriverbank filtration (i.e. natural filtration) provides the 2.0 log reduction ofCryptosporidium required under the Interim Enhanced Surface Water Treatment Rule(e.g. riverbank filtration is the primary filtration process). Using multiple surrogates ofvarious sizes encompassing those of Giardia and Cryptosporidium, the utilitydemonstrated 2.0-log reductions in over 90 percent of matched-data pairs. No Giardia orCryptosporidium were found in any of the 170 groundwater samples. This level ofremoval was achieved during the summer months when infiltration rates are high due toincreased river stage and well-field production. Includes 19 references, tables, figures.

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Edition: Vol. - No. Published: 11/01/2005 Number of Pages: 19File Size: 1 file , 620 KB