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Treatment Changes Letter
October 29, 2008
Dear Valued Customer, The Portland Water District (PWD) understands the importance of keeping our large industrial users, as well as those users with especially sensitive water quality needs, informed of significant water treatment changes. Advanced notification allows customers to prepare individual treatment systems to meet their unique water quality needs. This letter is to inform your company that a significant change in PWD water treatment process will be implemented over the next year. As part of the PWD’s corrosion control program, a corrosion inhibitor, zinc orthophosphate, is currently added to finished water at a dosage of 2.2 mg/L as orthophosphate (PO4). This chemical addition, in conjunction with pH and chlorine residual adjustment, has reduced both lead solubility and iron corrosion in PWD & customer water piping. These corrosion control measures have also helped the PWD to meet EPA Lead & Copper Rule (LCR) action levels. The PWD believes the best water treatment is one that meets or exceeds all EPA standards at the lowest possible cost and environmental impact. Having been in compliance with the LCR since 2001, the PWD is now seeking to further optimize corrosion control. With that in mind, data analysis strongly suggests the PWD can lower current zinc orthophosphate dosage without jeopardizing LCR compliance. The change, which was approved by and coordinated with the Maine Drinking Water Program, would effectively save PWD customers an estimated $200,000 annually and should not affect current distribution system lead, copper, iron, pH, or chlorine levels. To minimize water quality changes, the zinc orthophosphate dosage reduction will be done incrementally, over 6 months, according to the following schedule:
PWD is confident this change will not adversely impact water quality. However, customers are being notified in case their processes are sensitive to changes in zinc or orthophosphate levels. Please feel free to contact me with questions or concerns regarding this treatment change. Sincerely, Joel K. Anderson, Chief Operator Sebago Lake Water Treatment Facility (207) 774-5961 (x3303)
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