Wednesday, March 12, 2014

Frozen water lines and sewer lines don't mix!

Pipe Thawing Cross Connection/Contamination
by Paul Gladen

The issue of frozen pipes is at an all-time high around the state this year.
Cities are facing several issues of how to get the lines cleared and what to tell citizens on how to go about enlisting services to clear the lines. The two methods used are electrically heating the lines using welding equipment or specific line thawing equipment designed to heat the lines electrically and the second is using a hot water pulse machine to melt the ice. Both have their advantages and disadvantages. With the electric there is the possibility of stray electricity damaging the homes electrical system and or appliances or a cause of fire in the home being worked on or neighboring homes near the property. With the hot water machines there is a potential for cross connection contamination of the domestic water system.  The cross connection contamination concern was brought up by the Owatonna Public Utilities in response to our last blog on thawing water pipes. After talking with Owatonna Public Utilities and others on the issue it was felt that other cities could benefit from some guidance and direction on the cross connection contamination hazards and best practices.  

The hazards of contamination of drinking water during the thawing process is a result of the process involved in using the equipment. The jetting and hot water pulse equipment introduces a feed line directly into the water pipe and uses pressurized hot water to cut through and melt the ice. These machines have a hot water tank that recirculates the hot water from a heating tank on the machine pumping it through the feed tube to the ice blockage. The equipment needs to be properly taken care of and good housekeeping practices need to be followed by the operators (contractors or the city/utility) of the equipment in order to reduce the potential for contamination. There is a potential for these machines to have been used to clear sewer and drain lines which can introduce bacteria in to the domestic water supply. It would be a good practice for plumbing operators to have dedicated equipment for domestic water work and not use it for any other purpose.

Owatonna Public Utilities has put together a notice Owatonna Public Utilities sample notice to contractors that the city plans on distributing to the contractors in the area as well as to the citizens who have frozen lines. The notice outlines the best practices which should be followed by the plumbing contractors, and city utilities as well, to reduce the chance of contamination. These steps  are considered best practices for reducing contamination during the hot water thawing method. Following these recommendations will not totally eliminate the possibility of contamination but are felt to be good practice and a positive step in significantly reducing it.

Thank you to the people at the Owatonna Public Utilities Department for their contribution to this issue. A copy of the Owatonna notice is accessible in an attachment as an example for others use in the development their own notice.


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