Laserfiche WebLink
overexcavation. Groundwater was encountered at an average depth of 23.7 feet <br /> below surface grade (bsg). <br /> The groundwater sample collected and analyzed from HP-3 revealed benzene at 160 <br /> micrograms per liter (µg11), prompting the SJCPHS-EHD to order the completion of <br /> { three monitoring wells for groundwater direction and gradient determination, and <br /> ! possible definition of the contaminant migratory path. <br /> Drilling, Sampling, Completion, and Development of Initial Monitoring Wells <br /> On June 6, 1994, soil borings 4, 5, and 6 were drilled and completed as groundwater <br /> ' j monitoring wells MW-4, MW-5, and MW-6. This sequence of well numbers was <br /> selected in order to avoid confusion regarding the previous HydropunchTm numbers <br /> HP-1, HP-2, and HP-3. The monitoring well locations are depicted on Figures 2 and 3. <br /> Monitoring wells MW-4, MW-5, and MW-6 were first sounded on June 24, 1994. W.W. <br /> Irwin, Inc. contacted the piezometric surface in each well at an average depth of 14.82 <br /> feet bsg. The sounding depths were converted to groundwater elevations utilizing well <br /> casing-top elevations established on June 13, 1994 by Duane Kimball, Modesto- <br /> based, California-licensed Land Surveyor No. 4378. <br /> Groundwater samples collected from MW-4, MW-5, and MW-6 were received at <br /> Sherwood Labs on June 21, 1994. The results of the analysis of the sample collected <br /> -= from MW-6 indicated that the groundwater underlying that vicinity was impacted with <br /> TPH-g and BTEX analytes exceeding the Maximum Contamination Levels (MCLs) set <br /> by the California Department of Health Services. <br /> Groundwater Monitoring Activities <br /> ' The SJCPHS-EHS required that groundwater monitoring and the recording of tidal <br /> data be undertaken from August 1994 through January 1995. Samplings of MW-4, <br /> MW-5, and MW-6 were performed in September and December of 1994. Soundings <br /> were performed monthly. Local tidal influences (clock-times and heights) at Stockton <br /> were converted monthly from available tidal table information on the dates of <br /> k>� soundings of the three wells. The Project Status Report of Ground-Water Monitoring <br /> (W.W. Irwin, Inc., January 30, 1995) contained data which, until the Problem <br /> Assessment Report was issued on August 8, 1995, were the most recent up to that <br /> time regarding site conditions at Village West Marina. <br /> DAYNE L. FRARY, GEOLOGIST 3 <br /> > � 1296-012.197 <br /> .;i <br />