AWWA ACE68923

The City of Ottawa, Ontario, Canada operates and maintains 200,000 service connections and 3000 km ofwatermain, some dating back to 1874. Corrosion control, primarily through pHadjustment, has been practiced since 1932. In recent years, the corrosion control strategyhas been reviewed and updated to provide better protection of the distribution system.In 2002, a localized area of the distribution system experienced elevated lead levels inresidential water samples. The situation was resolved through adjustment of thecorrosion control strategy. Recent initiatives have been undertaken to monitor corrosionin several pipe loop systems and determine optimum pH conditions to minimize leaddissolution and iron corrosion.During 2006/2007 an intensive study was carried out to evaluate typical lead exposuresdue to piping and plumbing materials and to assess the impact of lead service linereplacement. Lead profiles and customer exposures were investigated under a variety ofconditions including fully flushed, 30-minute stagnation, 6-hour stagnation, and randomexposure protocols in both warm and cold water conditions. Based on the resultsobserved, regulatory compliance would most likely be achieved using the currentsampling protocols. However, increased lead concentrations were often observed for thesubsequent Litre-3, Litre-4, and Litre-5 samples in homes with lead service lines.Customer lead intake through drinking water can be effectively minimized by theapplication of optimal corrosion control and a full understanding of actual lead exposurepatterns. Includes 11 references, table, figures.

Product Details

Edition:

Vol. - No.

Published:

11/01/2008

Number of Pages:

51

File Size:

1 file , 2.7 MB