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� . <br /> • Page 2 <br /> • Periodic intrawell statistically significant increases in dissolved chloride, dissolved iron, <br /> dissolved manganese, sulfate, and dissolved solids at certain shallow and deep wells since <br /> the groundwater monitoring wells were installed in 1992. <br /> City staff does not believe that the manganese concentrations pose a health threat to either <br /> humans or aquatic life. <br /> Water Production staff has met with representatives of IEPA concerning these conditions, • <br /> and the City is required to conduct an Assessment Monitoring Plan. The plan will: <br /> • Determine the source of the elevated manganese coneentrations in the shallow and deep <br /> wells; <br /> • Define the extent of elevated manganese concentrations in the aquifer system at the <br /> Corley Landfill site; � <br /> • Assess the potential threat of the elevated manganese concentrations to human health and <br /> the environment; <br /> • Detertnine the source of increased concentrations of dissolved chloride, manganese, <br /> sulfate, and dissolved solids in the shallow downgradient wells and the periodic increases <br /> that occur at selected wells; and <br /> • Develop the information needed to prepare subsequent Potential Impact Assessment and <br /> Remedial Action Plans, should those be determined to be necessary. <br /> The City requested a proposal from environmental professionals at Dynegy (formerly <br /> Illinova) Corporation to prepare and manage the assessment monitoring plan. Dynegy was <br /> selected to prepare a proposal due to the specialized nature of the work and Dynegy's previous <br /> experience, both for themselves and for other outside customers. Dynegy has also done several <br /> other environmental projects for the City of Decatur, such as preparation of the Annual <br /> Groundwater Monitoring Report required by IEPA and sampling/analysis of groundwater <br /> samples in the Vulcan Lake and Lake Tokorozawa. The ma�cimum not to exceed fee for this <br /> project is $42,535. Funding will come from the Water Fund. <br /> Staff recommends that Council approve the attached resolution for the Assessment <br /> Monitoring Plan. Staff will be available at the Council meeting to answer questions. <br /> Attach.. 2 <br /> cc: Tom Davis, Dynegy <br />