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 I I Section B: Neighboring Environmental Site On pages D-8 and 9 it states that surface water as well as shallow and deep groundwater has exhibited signs of organic and inorganic contamination attributable to the Oak Grove Landfill. It is further stated that the extent of this groundwater contamination may impact the southwestern corne~r, and western portions of Site D. However, the exact nature and extent of groundwv~terLcontamination was not discussed. These potential existing groundwater quality impacts could have a profound bearing on the site suitability standpoint fi-om both existing groundwater quality conditions and as well as an example of the lack of natural hydrogeologic conditions able to provide groundwater quality impact protection from releases of contaminants. e With existing groundwater contamination present, a remedial action plan is needed to address corrective actions to be undertaken. Activities resulting as a result of the implementation of any remedial action plan could directly impact conditions at Site D. These concerns need to be addressed. This presence of trace contaminants in the buried outwash on p. D-9 would indicate that the site till layer is not as competent an aquiclude as was presented. On p. D-8 there is the first of many conflicts concerning the nature of the 'intermediate till layer (local aquitard). Earlier reference (p. D-7) indicate that a coarse-grained layer in the till (referred to in the report as Qgt,) may provide a hydraulic connection between upper water table aquifer (Qow) and the lower outwash sand aquifer (Obo). Results of pump test (p. D-66) indicate that such a hydraulic connection exists. Examination of the cross-sections show that the region where the pump test was performed is not the worst case for possible hydraulic connection. Therefore, the connection may be greater in other portions of the site. 9