Bossier City's Chlorine Burn and the Potential Effect on CBB Members
February 24, 2014
Subtitle: Chlorine, Chloramines and a Discussion on Water Disinfection
As most of our members are aware, all of the water CBB distributes to our members is purchased from the City of Bossier City (Bossier). Beginning on Friday, February 21, 2014 Bossier is carrying out a "Chlorine Burn" throughout their water system. Therefore, between the end of February and the end of April our members may experience an increased taste and smell of chlorine since our water does come from Bossier.
The water is safe. Even when chlorine levels are elevated during the burn, the levels are well within EPA guidelines and rules for maximum chlorine levels. Hopefully this will not last more than a month, but Bossier has officially announced the burn will last 60 days.
Bossier disinfects their water with chloramines, a mixture of chlorine and ammonia (a very much diluted ammonia). The ammonia in the mix results in a longer lasting disinfectant, therefore not as much chlorine is needed to maintain safe disinfectant levels throughout the system. This is important because when less chlorine is introduced into the system there are fewer disinfectant byproducts (DBPs) produced as a result of the process. DBPs are regulated by the EPA, and are suspected carcinogens in large quantities over long periods of time. All water systems work to reduce these DBPs, including CBB.
There are other chemical reactions that can take place when ammonia is introduced into the mix, most notably a process called "Nitrification". Nitrification is not a good thing because it produces food for any bacteria that might be in the water, and it consumes available chlorine thus reducing the disinfectant levels. This produces a "double whammy" effect - less chlorine to kill any bacteria and more food for the bacteria. Therefore all systems that use chloramines must have a plan to ensure this process does not occur; and if it does the nitrification must be caught early and remedied quickly.
The Chlorine Burn that that Bossier is performing is part of their plan to reduce the possibility of nitrification occurring. Instead of chloramines being used for disinfectant free chlorine is introduced in larger than normal quantities (without ammonia) for a short time until a certain, minimum, free chlorine level is reached at all points in their system. Once this level is reached it will be held for one week. After that week the free chlorine will be shut off and the reintroduction of chloramines will begin. As a side note, CBB is also developing a Nitrification Control Plan that must be submitted to the State by the end of February.
Unlike Bossier, CBB does not use chloramines, but we add free chlorine when needed to boost disinfectant levels in our system. There are times that the disinfectant added by Bossier is sufficient to keep the minimum required levels of chlorine throughout our system without CBB having to add anything. CBB monitors chlorine levels daily at several points in our system with additional checks at a variety of other sites during each month. Free chlorine is added only when needed.
Last fall all water systems in the State of Louisiana were mandated by an Emergency Rule to raise the minimum levels of chlorine residuals at all points in our system. Extra monitoring was also mandated to ensure that these new levels were in fact being maintained. The Emergency Rule was brought about by the discovery of a rare amoeba found in a couple of water systems in the State. CBB responded to this ruling and raised our free chlorine feed rate for a short period of time to make sure the end points of the system were in compliance with the new standards. In effect we did our own chlorine burn last fall (November 2013). As we increased our monitoring and flushing of our system lines we were able to bring down the amount of chlorine we need to maintain the new standards. At different points during the past few months we have been able to rely on the disinfectant feed by Bossier and not had to add any chlorine to our system. We expecting the need to return to adding chlorine when the weather gets warmer. We also are expecting to have to add more chlorine than we have in the past to maintain the new, higher standards required by the State. Increased amounts of chlorine will possibly result in higher than normal DBPs (mentioned earlier). DBP levels are closely monitored and reported to the State. The EPA puts strict limits on the amount of DBPs that can be present in drinking water. Because of the balancing that will be necessary (enough chlorine to meet new State requirements vs. possible increased DBPs) CBB has retained the services of an engineering firm to design a new disinfectant system with an eye toward switching to chloramines. This will allow CBB to maintain the new, higher chlorine residual levels at all points in our system, while keeping disinfectant byproducts to a minimum. We will keep everyone posted on how this project is proceeding.
If you have any questions or concerns about chlorine taste or smell, or any water quality questions at all please call office at 318-965-0015.