Agenda - Council - 09/25/1990 - Laserfiche WebLink

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I I I I I ! I I I I I I I I I I ! I I , o6 data is not known for 66% of the wells in the study area. Care should be exercised when reporting or interpreting aquifer usage percentages. Paraphrased, the last paragraph of the Regional Hydrogeology section p. P-95) states that for wells with known depths, 93% are completed in aquifers below an aquitard, while 7% are completed in the water table-aquifer, and that water table wells would most likely be potentially impacted by' the proposed landfill development. If the aquitards were continuous throughout the study area, this would be an important statement because 93% of the wells would have some natural protection from potential contamination due to the presence of the aquitards. However, the most significant aquitard, namely the glacial till, is not continuous beneath the study area due to the presence of a tunnel valley. The tunnel valley permits direct hydraulic connection between the water table aquifer, lower outwash aquifer, and bedrock aquifer. Therefore, it should be made very ~ clear tl3at within .~s :~tUdg are~,atl, iof the aquifers are at significant-risk-to impacts from 'the iprOpOS~i~ndfill deX;el6Pment..~: Section E: Site Geology On pages P-101 through P-104, the scope of drilling work is discussed. At various stages of the EIS site investigation, decisions were made to limit the depth and locations of various soil borings or wells to minimize the potential for cross- contamination of aquifers. The basis for these decisions has some merit; but in so doing the various decision making bodies have sent a clear message that drilling beneath Site P is a sensitive issue. Drilling either soil borings or wells requires special care and higher costs. Hence, due to existing groundwater contamination, costs for potential future investigations of subsurface conditions beneath Site P would be greater than the costs for a comparable site with no existing groundwater contamination. 4