AWWA ACE65572

The City of Ottawa supplies high quality drinking water to a population of 780,000through the operation of two surface water treatment plants and a large distributionsystem some of which dates back to 1874. Since the source water (Ottawa River) tendsto be aggressive owing to its low hardness and alkalinity, corrosion control has beenpracticed for 75 years, primarily through pH adjustment. In recent years, the corrosioncontrol strategy has been reviewed and updated to provide better protection of thedistribution system.In 2002, a localized area of the distribution system experienced elevated lead levels inresidential water samples that exceeded the drinking water standard for flowing leadconcentrations at the point of consumption (10.0 µg/L). The situation was resolvedthrough quick adjustment of the corrosion control strategy. Recent initiatives have beenundertaken to monitor corrosion in several pipe loop systems and determine optimum pHconditions to minimize lead and iron dissolution.In addition, a residential testing program has been carried out to determine typical leadexposures due to piping and plumbing materials and to assess the impact of lead serviceline replacement. The testing has evaluated lead arising from both transitory andstagnation contributions to lead in the tap water. The sampling program makes use ofsampling methods described in Health Canada's proposed Guideline CorrosionControl in Drinking Water Distribution Systems as well as random exposure testing toassess typical exposure through domestic water use. Includes figures.

Product Details

Edition:

Vol. - No.

Published:

06/01/2007

Number of Pages:

65

File Size:

1 file , 1.8 MB