Laserfiche WebLink
May 2013 <br />Groundwater POC Memorandum ♦ 13 <br />5.0 SUMMARY AND RECOMMENDATIONS <br />The results of the 2012 Field Investigation and recent groundwater monitoring were used to <br />develop the following POC recommendations for the areas east of 1 -Dam (near MLGW -7), <br />in the Potato Gulch drainage, and east of 3 -Dam. <br />• Based on the non -water bearing nature of the Tertiary Troublesome Formation (Tt), <br />and Precambrian bedrock (Xg), no POC monitor wells are recommended for these <br />units. <br />• Based on the thickness of saturated Quaternary glacial sediments (Qd), and the <br />calculated downward vertical gradients, it is recommended that MGLW -15, screened <br />near the base of the Qd, and nested shallow well MLGW -7 be POC monitor wells <br />for the area east of 1 -Dam. <br />• Based on existing geologic and hydrologic information, including the existence of a <br />bedrock ridge northeast of 1 -Dam and the intermittent occurrence of groundwater in <br />existing monitor wells, there is currently no basis for establishing a POC well north <br />of 1 -Dam or in the Potato Gulch drainage. AJAX /CCA recommend continued <br />internal monitoring of wells located north of 1 -Dam. Future investigations should <br />also be considered to better define subsurface geology and characterize groundwater <br />flow and transport pathways. <br />• Initial sampling of monitor wells located east of 3 -Dam showed that three of five <br />monitor wells installed in 2012 were dry. These observations do not indicate the <br />existence of a laterally extensive aquifer system in this area; and therefore we do not <br />recommend the establishment of a POC well at this time. AJAX /CCA recommends <br />continued monitoring of wells east of 3 -Dam to evaluate whether seasonal variations <br />could form a transient aquifer system. We recommend the establishment of a <br />potential POC in the area of 3 -Dam be reconsidered following the completion of <br />five quarterly monitoring events. <br />