IMPORTANT INFORMATION ABOUT YOUR DRINKING WATER
September 25, 2009
The construction work to eliminate the mineral problems in our water is finally
As long time users of our system realize, the levels of manganese and iron in our well
water have both increased over the past number of years. We have now finished the
construction work on the Water Filtration Plant and the filtration equipment was put on-
line in May. We are adjusting and fine-tuning the filtration system as the final phase of
work. Here is a brief summary of where we are as of this writing:
• The iron removal process is going very well and we have had consistent levels of less than 0.1 milligrams per liter since about the third week of May. Our filtration process target was to reduce the iron to below the maximum contamination level (MCL) recommendation of 0.3 mg/l. We consistently surpass that goal.
• Manganese removal is now progressing well. The Degremont biological manganese removal process was always known to take much longer than the iron removal process to get up to full effectiveness so having the full design level of removal not immediately evident was anticipated. As was discussed in the June 2009 Consumer Confidence Report and at numerous Water Board and Select Board meetings (many of which were televised and/or reported upon), the anticipated timing of full manganese removal effectiveness was mid-summer. Instead, the manganese removal level seemed to plateau at about one-third removal and stubbornly stuck there. We are pleased to report that, within the last several days, the level of manganese in the water coming out of the filters has dropped very significantly and now is on a definite, steady and fairly rapid decline. As of yesterday, the manganese is about 75% removed from the water and, if the recently experienced decline rate continues, we should be approaching our goal of less than 0.05 mg/l within a short time. Outside lab and in-house testing results have both confirmed this very positive change. The Degremont company had indicated that it was fairly typical to have a period of
partial removal with very slow change followed by a fairly sudden and dramatic improvement to full effectiveness but, further, that the exact timing could not be precisely determined owing to the fact that we are dealing with a biological process. While waiting for the process to fully “kick-in”, we were with baited breath and increasingly nervous with anticipation as each week went by. Happily, it now appears as though we are well on our way to reaching the manganese removal goal too.
• The total filtration process now increases the pH of the water we supply. Our raw water has always been on the acid side of neutral, but now our finished water has a pH which is just slightly above neutral (7.0). You may find that soap products seem to work a little easier and that you get a bit more suds from use of the same amount of soap or detergent than previously. This rise in pH may also serve to reduce the corrosiveness of the water. Cavendish Municipal Water System - Billing Insert September 2009
• A part of the filtration process involves the injection of air into the water. The air injection is needed for the biological process to be fully effective. The rate of air injection has been at particularly high levels as a needed condition for the media
to become fully fertile for the processing. We are hoping that, when the filtration media becomes fully developed, the levels of air in the water going out into the distribution system will diminish and will not be as evident to users. You undoubtedly have noticed that, at times, the water you pour into a glass may at first have a bit of a milky appearance being caused by tiny bubbles of air. If you let a glass of this water stand for a few moments, it turns very clear as the micro- bubbles rise to the surface and dissipate. If a water line in your house is not used for a while, some of the air may come out of solution and will cause a spitting or sputtering at the faucet as the air is released. This may be most noticeable on an upper floor. While the air is perfectly harmless as a health issue, we hope to eliminate the nuisance of the sputtering as the amount of air in the distribution lines is reduced. We are currently working on this issue.
• The water storage tanks [Proctorsville 300,000 gallon and Cavendish 250,000 gallon] are scheduled to be cleaned and inspected during the first two weeks of October. Work on these tanks should have no impact on water quality.
• Following tank cleaning, there will be a flushing of system lines and hydrants. The flushing is scheduled to take place October 28 through the 30. There will be a notice sent out about 10 days before the flushing with more details on the
flushing activity and suggestions as to procedures that homeowners and commercial customers can follow to further purge their in-house plumbing immediately following the Town’s flush.
Thank you for the patience you have shown as we have worked to resolve the iron and manganese problem. It has been a lengthy process to get our water system capital improvements completed, but we are now almost done!
The Cavendish Municipal Water System Has Had Levels of Manganese Above Drinking Water Standards The Cavendish Public Water System has had concentrations of manganese which exceeded the Environmental Protection Agency and Vermont Department of Health lifetime Health Advisories of 0.3 mg/L. In 2005, 2006, 2007 and 2008 the levels of manganese in the Cavendish system were 2.5 mg/L, 2.1 mg/L, 1.8 mg/l and 2.57 mg/l respectively. Although the new filtration system now in operation is intended to reduce the amount of manganese to below 0.05 mg/l, the level, while now significantly reduced, has not yet dropped to below the advisory level although that should occur soon.
Manganese is noted to be an essential element, however, most of the manganese needed on a daily basis generally comes from the food we eat. Long-term consumption of high concentrations of manganese in drinking water may cause adverse neurological health effects. Children and people with liver disease are more susceptible to the health effects of manganese. If you have specific health concerns, consult your doctor. Additional information on this topic and other water system topics is included in the Consumer Confidence Report which is made available and distributed each June. Additional copies of the report published in June of 2009 are available for the asking if you call the office at 226-7291, stop by the office, or send us a note at Cavendish Municipal Water System, P.O. Box 126, 37 High Street, Cavendish, Vermont 05142.