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After a detailed investigation on the failure of copper water service pipes in theBrown Deer, Wisconsin water distribution system, microbiologically influencedcorrosion (MIC) was found to be the cause. Typical characteristics of MIC are explained inthis report and include: jagged pit morphology;presence of microorganisms only in corrosion debris and pits;initiation of corrosion at the extreme of the water system, especially in areas ofhigh water age;initiation of corrosion at low points in pipe lines;inadequate disinfection levels in the water at the entry points to the system;further reduction of disinfection levels in the corroded areas of the system; and,a water treatment history that points to an increase in nutrients formicroorganisms just before pipes began to fail. To remediate Brown Deer's problem of copper pipe biocorrosion, the following actionswere taken:a procedure for monitoring the distribution system was created to routinelytrack disinfection levels, ammonia levels, heterotrophic plate count(microorganisms), and other parameters of special interest;disinfection boosting facilities are being planned with a fast-track design for thefirst facility; and,system cleaning was continued and extended. The Brown Deer Water Utilityhas an aggressive program of leak detection and water service line replacementand will continue that. Plans are also being made for the pigging of water mainsto remove biofilms from pipe walls. Discussions are on-going as to how toapproach the cleaning of private property such as the pro-active replacement ofwater service lines and shock chlorination of interior plumbing systems aftersystem-wide disinfection is established. Includes 20 references, tables, figures.

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Edition: Vol. - No. Published: 11/02/2003 Number of Pages: 15File Size: 1 file , 750 KB