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Many authors have documented the positive effects of flushing on water quality. Oberoi(1994), in a study on the Edmonton water network, found that chlorineresiduals and turbidity levels were improved by flushing and the benefits remained for upto two years. Two other authors (Kuehn et al., 2001; Cossins et al., 1999) found lowerturbidity levels in the network following UDF. Coliform positive episodes were alsofound to be reduced after UDF in Fort Belvoir, according to Antoun et al. (1997).Another study conducted by the same authors in Virginia and North Carolina came to thesame conclusions (Antoun et al., 1999).Although the benefits of UDF have been often described, there has not been extensiveanalysis of the potential adverse short term effects of flushing, due to the incompleteremoval of loose deposits at the end of the procedure. The objective of this study wasto identify the short term (1 day to 1 week) effects of flushing on water quality.To address this issue, three unidirectional flushing campaigns were performed inJonquiere (Quebec, Canada) from May 2001 to May 2002. UDF conditions werecharacterized by velocities of 1 to 2 m/s and a closure criterion of 5 NTU turbidity.Water quality samples were collected before, shortly after (24 hours) and one week afterflushing and analyzed for parameters that included: turbidity, chlorine residual, total iron, total coliforms, total viable counts,total direct counts and heterotrophic plate counts. Seven sampling locations in total wereselected for this analysis: two at the plants (as a control for influent); and five in theselected sites. A total of 20 analyses were performed for each parameter. Water qualitydata from the flushing sites were compared to samples from the plants in order todisregard variations attributable to distributed water quality. Includes 7 references, tables, figure.

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Edition: Vol. - No. Published: 11/02/2003 Number of Pages: 7File Size: 1 file , 300 KB