The City of Ottawa, Ontario, Canada operates and maintains 200,000 service connections and 3000 km of
watermain, some dating back to 1874. Corrosion control, primarily through pH
adjustment, has been practiced since 1932. In recent years, the corrosion control strategy
has 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 in
residential water samples. The situation was resolved through adjustment of the
corrosion control strategy. Recent initiatives have been undertaken to monitor corrosion
in several pipe loop systems and determine optimum pH conditions to minimize lead
dissolution and iron corrosion.
During 2006/2007 an intensive study was carried out to evaluate typical lead exposures
due to piping and plumbing materials and to assess the impact of lead service line
replacement. Lead profiles and customer exposures were investigated under a variety of
conditions including fully flushed, 30-minute stagnation, 6-hour stagnation, and random
exposure protocols in both warm and cold water conditions. Based on the results
observed, regulatory compliance would most likely be achieved using the current
sampling protocols. However, increased lead concentrations were often observed for the
subsequent 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 the
application of optimal corrosion control and a full understanding of actual lead exposure
patterns. Includes 11 references, table, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 2.7 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 51 |
| Published : | 11/01/2008 |
