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DR:� � "!' <br />rY os - o� <br />F. If groundwater at the site is contaminated, note the geologic makeup of the affected <br />aquifer (sand/gravel, till, lacustrine clay, etc.), and the estimated average linear velocity <br />fbe sure to indicate how this number was determined). <br />GEOLOGY: <br />The uppermost strati�raphic unit consists of lacustrine sediments composed of silty sand <br />that is present from near �rat�nd surface to depths ran�in� from 14 to 16 feet b�s. The <br />upper siltv sand unit is underlain bv relativelv impermeable lean �rav clav, ra��fne in <br />thickness from 12 to 14 feet. This �rav clav unit is believed to have been debosited as <br />�lacial till (Des Moines Lobel. All borin�s that were advanced to sufficient denth durin� <br />the investi�ation encountered the clav unit. su��estin� it is a brominent strati�rabhic unit <br />across the studv area. The clav unit is underlain �� well sorted sand that extends to a <br />depth of at least 54 feet below �round surface (�� depth of the deepest borin� advanced at <br />the Site . <br />HYDROLOGY: <br />The c�'UC-irnbae��d �roundwater svstem is a shallow, unconfined, berched svstem that <br />occurs within the upper silty sand unit on top of the clav unit. Depth to water in the upper <br />silty sand unit occurs at depths ran�in�: from approximately fve to ten feet �i�. Grain size <br />distribution testin� of a material samble collected from one of the monitorin� wells <br />classifies the unper ��dre�stratigrauhic unit as a silty sand with little �ravel. Based on <br />�rain size analvsis (SheAard Method (�989y1, the hvdraulic conductivitv of the shallow <br />perched svstem is approximatelv 2.0 x 10" cmisec for 5.7 ftlt�avl. Groundwater in the <br />shallow perched �roundwater svstem flows to the eastlnorf�east under hvdraulic �radien�� <br />ran�in� from 0.0025 to 0.019. <br />G. Briefly describe possible exposure scenarios posed by identified contamination at the <br />� site (i.e,, ingestion or human contact with contaminated soil, consumption of <br />contaminated groundwater, ecological impacts, etc.), and nearby receptors that could be <br />affected by conta�ina��s migrating from site (high value vveCland/ct�eeks/ rivers, etc.). <br />SOIL: Chlorinated VOCs in unsaturated soil beneath existin� structures at the site do not <br />���c an im�aa��i�i� rask to h� n x hralth $: d v�r��•ironment, �j�ts►risr�z�:� �'Q� <br />cottee�traL��s iri �at, fifl�ur�#rd a.r31� ����h �h� s Erai� �ia ����ri 4� ti I Learh,in� �': <br />t��.Vs� ;��� i.tittr���iox�� i� c�ti�t�i�cr�[i #av �� :� �riprCC kXF C"i��CIS ir, ry����,� LIiL(I�I�iit� <br />tivat �'9�9���n a�ti�� �`OC'� �x� u�rE��#u�t�� ���I � th rtEE� trt� t c�rfi ai .� <br />considered to be a source of cVOV vabors in the subsurface. <br />GR(?U1�D�1F�►'I'l:�l�: �. FFIlkC3 FkM{l'{� �''�1�:� I�� ti��� ir���rattc�d the � ki M 14,x33 �rt r4 �cd �r�E�a��l M�a €re <br />�t F n���4c g��. �'�i �� i i�'���'s �n�a�nc�� s�,�.cr,,d� rt�� pos� �n iinmeEii�rEs�€ <br />y ■ - _ -�'M'��- �� -�G��'1'1'1 <br />f.o hu�arr h��sl#h ar �h� �rr••ir��nrrrerrf, f�ee�xis� �tee xh�lE�tir ��«�e[E �t����tdn�.�e� �>st�m u <br />t � as a t suppl �. {'l�ti�trar�s��� �'t��s E�� rN� s���z�w Y�� d; r �� <br />_ }., — - <br />are, however, considered to be the source of c'V'OCs in subsurface soil vapors, which would <br />bose a risk to residents occubvin� homes constructed on the brobertv in tlte future. <br />Cleanup 9 <br />