Minutes - Public Works Committee - 11/20/2001

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Cybernet that models Ramsey's entire water distribution system. Causes of Discolored Water Complaints: As mentioned in the above discussion, the velocity of the water in the pipes is relatively low and unidirectional during normal operation of the system. The main cause of discoloration to the municipal water customer is a significant increase to the velocity and/or change in direction of flow of water. Below is a list of events that most often trigger a discolored water complaint: ? ? ? ? ? Flushing/valve maintenance Water trucks/filling Operation changes or scheduled maintenance Emergency shutdowns Fire flow Accident or main breaks Current City Practice: The current program is designed to ensure the customers of Ramsey's water system a continuous supply of clean water during normal operation. Although flushing generates the most complaints for discolored water, it is also essential to control the amount of iron and manganese in the pipes and is essential for a successful valve maintenance program. In addition to the flushing program the City introduces a liquid polyphosphate into the water supply to sequester the iron and manganese. This sequestration tends to keep the particles in dissolved form but does not remove the iron and manganese from the water. Eventually, residual iron and manganese builds up in the pipes and needs to be flushed. This residual seems to build up more frequently in the areas of the system that have longer detention times such as dead end lines. Staff also ensures that contractors of Capital Improvement projects notify residents and customer service personnel, in advance, about activities that could alter the water system are taking place. Alternatives that could help curb the frequency of discolored water complaint: The ultimate solution to the problem would be the addition of an iron/manganese treatment plant to remove these particles before entering into the system. This alternative is costly but will likely be a topic to be discussed in the not too distant future due to the discussions being held at the federal level. Water trucks should be filled from designated hydrants that are supplied by larger pipes. This will cut down on the flow variation that was mentioned earlier as a cause of complaints. Contractors for Capital Improvement projects should be required to fill their water trucks from designated hydrants and that the area is flushed prior to construction activity taking place. Public Works Committee/November 20, 2001 Page 11 of 13