Maintaining drinking water quality in the Dominion Park area of West Saint John has long been a challenge. Why is continuous flushing of the system needed in the area; and why is more water flushed during warmer summer months? Experience this summer is a classic illustration of why safe, clean drinking water involves much more than building new water treatment facilities.
Good quality drinking water is free of disease causing micro-organisms and harmful chemicals; it has no bad odours or undue colour. Saint John Water tests the water system diligently through a Health Department approved sampling plan to make sure drinking water is safe. In fact, it is this regular sampling that led to the discovery of bacteriological readings in the distribution system. A localized boil water order was issued initially on Friday July 30th for about 25 residences on Tippett Drive (west of Mary’s Place) and including Mary’s Place, Mackie Lane and Cove Roadway. Since then, daily sampling and analysis has been carried out. The results of this subsequent sampling led to a necessary expansion of the boil order on Tuesday, August 3rd to include approximately 75 more homes in the area after the bridge on Greenhead Road.
Although we regret the inconvenience of a boil water order, the health and safety of the public is always the primary concern of your water utility. The order is given to protect public health.
So, what is the situation; and what is the City of Saint John and Saint John Water doing about it?
SITUATION - CONDITIONS
Chlorine disinfection of drinking water serves two purposes; to initially inactivate or kill any micro-organisms in raw source water and, then, to prevent re-growth of micro-organisms as the water travels through the distribution system. Sufficient residual chlorine must be maintained in the water system to ensure its safety.
A combination of factors is at the root of the problem in the Dominion Park neighbourhood; long dead end lines, very warm water temperatures and exposed unlined cast iron piping through which the water flows. Each of these impacts the chlorine residual level and, with that, the potential for bacteria formation in the system. Build-up of corrosion material inside the unlined cast iron pipes has the greatest adverse impact on water quality.
Almost 70% of the water distribution piping in the Milford/Randolph peninsula is unlined cast iron, installed sometime before the 1970s. These mains are highly susceptible to build-up of internal corrosion materials, a particular concern along a 755 metre section of Greenhead Road, between Balmoral Crescent and Dwyer Road. Coupled with this are high water temperatures in both sources (Spruce Lake and Latimer Lake). Lake water temperatures have reached the record highs of recent years. Bacteria thrive in higher temperature conditions, feeding off naturally occurring organic matter in the unfiltered water.
Saint John Water Operations and Engineering staff has been working hard to address these conditions. Water quality testing is being conducted on a daily basis at a minimum of 8 locations and chlorine residual levels are being closely monitored. Also, we are in ongoing communication with regulators at the departments of Health and Environment.
System flushing has been intensified beyond usual levels - to increase flows and to move more fresh water into affected areas. The lower the water “residence time” in the system, the greater the likelihood chlorine residual and quality (no bacteriological presence) can be maintained.
After discussions with and permission from regulatory authorities, Operations staff developed and installed a temporary chlorine injection system at the PRV chamber on Church Avenue. Its commissioning (on Tuesday, August 10th) has enabled us to increase disinfection levels going into Milford/Randolph. After some calibration and testing, chlorine residual readings have begun to rise throughout the area.
Notices on the temporary chlorination system were delivered to the 100 homes impacted by the boil order on Tuesday and to others in the Milford/Randolph area by Wednesday. With higher disinfection levels, people should expect to detect a chlorine odour. This should not be of concern; elevated chlorine levels will be doing the job of preventing bacteriological re-growth.
Engineering staff has also determined that cleaning and lining of the problematic section of watermain along Greenhead Road is possible with some system adjustment by Operations. Staff has arranged with the contractor now working in the city to add this 755 metre section to the current contract. Work is to begin during the week of August 23rd. Although this will mean some inconvenience, it will produce significant improvements in the affected area’s water quality.
As planned, budgeted and scheduled, the infrastructure project along Dever Road includes a second watermain connection to Milford/Randolph. Once completed in the fall, the full cleaning and lining program for the greater area, including Dominion Park can go ahead. This major phase of the cleaning and lining program, planned for 2011/12, will have a very positive and permanent impact on water quality in this part of our community.
The City is working to improve the public water system across Saint John; Council has made this its foremost priority. It is vitally important that all remain focused on these efforts.
BOIL WATER ORDER
While the boil water order remains in effect at this time, we are optimistic the work being done will make the necessary difference. Water samples will continue to be collected daily, including through the week end. In order for the Medical Officer of Health to lift the boil water order, two consecutive sets of satisfactory bacteriological results are necessary - no less than 24 hours apart. Adequate chlorine residual levels must also be demonstrated - measured and maintained.
Paul Groody, Saint John Water