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toxicity, doses less than 5 mg per liter are used to treat defined areas of the pond; COST <br /> $180,0004200,000 <br /> Mr. York responded that due to cost, dredging could be eliminated. Regarding nutrient inactivation, <br /> Mr. York expressed concern that water would be mixed during winds, risking exposure to fish. Mr. <br /> York added that algae are always present and questioned the treatment's effectiveness if algae are <br /> layered on top of the aluminum creating an additional phosphorus source. Mr. Kretchmer responded <br /> that the goal was to break the cycle of continual release from the sediment. Mr. Kretchmer continued <br /> that fish could be protected by applying the aluminum in a checkerboard pattern to provide a refuge for <br /> the fish, noting that the aluminum flock remained in the sediment and would not migrate once it <br /> reaches the bottom. Mr. York suggested that the solar unit mixer appeared to be the most cost <br /> effective option for Santuit. Mr. York questioned the percentage of lawn fertilizer present in the total <br /> phosphorus percentage. Ms. MacDougall responded that a conservative estimate of the entire <br /> phosphorus load reduction, based on circulation, was determined by AECOM and that the entire 78% <br /> reduction could not be achieved by any method. It was estimated that it could be reduced to 17%with <br /> 100% reduction. Ms. MacDougall added that the circulation technique could be ineffective if there <br /> were not enough units in the pond. Mr. York supported the idea of circulation and added that federal <br /> funding was being sought to address the issue as soon as possible. It was suggested that each <br /> circulation unit could manage approximately 40 acres. Mr. York added that monitoring units were <br /> available in the pond to monitor the phosphorus and the effectiveness of the units. <br /> Mr. Waxman also spoke favorably regarding the success of the circulators at other locations. The <br /> Chair confirmed that the circulators would be a permanent fixture in the pond in order to address the <br /> phosphorus in the sediment. Mr. Baker expressed concern that the phosphorus would remain in the <br /> pond and suggested that the circulators would be a short term solution. Mr. Waxman noted draft <br /> legislation that would ban the use of phosphorus in fertilizers for existing lawns as an effort to limit the <br /> addition of phosphorus to the pond. Mr. Kretchmer summarized AECOM's recommendation to break <br /> the cycle of release by stopping the internal load and lowering the external phosphorus load to return to <br /> an improved state of the pond. Mr. Baker expressed interest in re-visiting the option of draw down <br /> since the pond seemed to be running higher than it was historically. Mr. Baker suggested running the <br /> pond 5 inches lower, or increase flushing with a partial draw down during the winter,which in the long <br /> run, could reduce phosphorus in the sediment. Mr. York agreed that the pond was running higher than <br /> normal and efforts were being made to lower the pond, but that the pond is flushing only 3 times each <br /> year and that increasing the flushing rate would not resolve problem.. Mr. Kretchmer will provide <br /> more details in the report regarding hydrology and nutrient load. <br /> The Chair questioned the longevity of the phosphorus in the sediment,to which Mr. Kretchmer <br /> confirmed that it would remain indefinitely since it was an element. The Chair questioned whether a <br /> combination of the recommendations would be effective, such as using alum for 50%of the pond and <br /> circulators for the remaining area but Mr. Kretchmer thought that it would be overkill. Mr. Kretchmer <br /> emphasized the need to eliminate watershed sources of phosphorus in order to utilize the alum <br /> treatment, which could then last for approximately 15 years. However, although results from the alum <br /> treatment would be immediate to address 90%of the phosphorus, it would be difficult to eliminate all <br /> watershed issues, requiring repeated alum treatments. Ms. Waygan recommended that, in the final <br /> report, Mr. Kretchmer bullet the specific watershed recommendations in order to highlight the ways in <br /> which the Town can impact the pond. <br /> Mr. Ralph Baker, owner of nearby cranberry bogs, questioned whether or not samples had been taken <br /> to determine whether the cranberry bogs were responsible for the addition of phosphorus. No forensic <br /> studies had been conducted. Mr. Ralph Baker also expressed frustration that bogs had often been <br /> 7 <br />