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1%00.1 %..� Groundwater Monitoring Report, Second Quarter 2006 (Secor). 2.2 Site Geology and Hydrogeology Soils underlying the Site consist of three laterally extensive fine-grained sand layers: Sand A, Sand B, and Sand C (Secor, 2006). Sand A is located 5 to 8 feet below ground surface(bgs)and is 3-to 10-thick. A clay layer has been encountered at approximately 10 to 15 feet bgs and is approximately two feet in thickness. Sand B is located between 25 to 35 feet bgs and is between 7-to 18-feet thick. Sand C is ? located between 50 and 65 feet bgs and is between 15-to 25-feet thick. Groundwater was observed in each of the three sand layers. The existing monitoring wells are screened across Sand A,except for monitoring wells MWO-1X and MW-8,which are screened across Sand B. Based on last quarter's groundwater sampling event depth to groundwater is approximately eight feet bgs. Groundwater flow is reported to be to the northeast with a gradient of 0.00075 feet per foot(ft/ft). A pump test conducted by Secor(June, 2006) used groundwater monitoring wells MW-2 and MWO-1X, which are screened across Sand A and Sand B,respectively. Similar amounts of measured drawdown were observed in both wells while pumping on the well in the other sand strata, suggesting hydraulic connectivity between Sand A and Sand B. It is not know if Sand C is connected hydraulically to Sand A and B. 3.0 SCOPE OF WORK The scope of work and objective for this proposed site assessment includes the following: ■ Install up to seven groundwater monitoring wells (MW-12 through MW-18) and located approximately as follows: o One groundwater monitoring well (MW-12)will be located in the planter alongside the eastern edge of South Harlan Road and directly west of existing groundwater monitoring well MWO-1, o One groundwater monitoring well (MW-13)will be located near the western edge of South Harlan Road and directly west of existing groundwater monitoring well MW-1, o One groundwater monitoring well (MW-14)will be located in Chandra Way and approximately 150 feet northeast of existing groundwater monitoring well MW-11, o One groundwater monitoring well (MW-15)will be located in the planter alongside the eastern edge of South Harlan Road and directly west of existing groundwater monitoring well MWO-3, o One groundwater monitoring well (MW-16)will be located adjacent to existing groundwater monitoring well MWO-1X, o If lab analysis of the grab groundwater sample collected early on from MW-12 indicates MTBE impact, then a groundwater monitoring well Environmental Remediation Group Page 2 Site Assessment Work Plan Project No.0406 Joe's Travel Plaza