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�/ el <br /> Quik Stop No 121 <br /> Additional On-Site and Offsite Soil and Groundwater Investigation <br /> Page 2 <br /> had changed approximately 90 degrees from the flow direction reported in the January 2000 <br /> quarterly report This change in flow direction was most likely due to the rapid rise of the water <br /> table from the winter rains Since the gradient is virtually flat, any variation in the water level <br /> within the three wells will impact the calculated flow direction at the site <br /> Based on the January and February 2000 sample results, the Central Valley Regional Water <br /> Quality Control Board (RWQCB) and the San Joaquin County, Public Health Services, <br /> Environmental Health Department (County) requested a Work Plan to further define the vertical <br /> and lateral extent of the contaminant plume at the Quik Stop site CCI was aware of the City of <br /> Manteca municipal well No 15, located approximately one-quarter mile southeast of the subject <br /> site, near the corner of Franciscan Way and Agate Street CCI proposed to collect soil and <br /> groundwater data between the Quik Stop Market site and the municipal well to determine if <br /> groundwater contamination was migrating toward the well In addition, CCI proposed to collect <br /> a grab water sample on the north side of West Louis Avenue (in front of the Exxon station)to <br /> determine whether groundwater contamination is migrating from that corner toward the Quik <br /> Stop site <br /> • Project Approach <br /> CCI retained VBI In-Situ Testing of Sacramento, California to perform the Cone Penetrometer <br /> Test(CPT) The CPT rig was used to gather soil lithology data from the surface to depths of <br /> approximately 3 5 to 79 feet and to collect groundwater samples from selected depth intervals for <br /> laboratory analysis The following scope of work was initiated before and during the <br /> investigation <br /> Scope of Work <br /> 1 Prepared a Health and Safety Plan to conduct field activities at the subject site, <br /> 2 Obtained encroachment permits from the City of Manteca and boring permits from <br /> San Joaquin County, <br /> 3 Hydraulically push 3 CPT holes to collect sounding data on the regional lithology, <br /> 4 Collect grab water samples from the 3 CPT holes, <br /> 5 Collected groundwater samples from the three site monitoring wells, <br /> 6 Analyze all groundwater samples for total petroleum hydrocarbons as gas (TPHg), <br /> benzene, toluene, ethylbenzene and total xylenes (BTEX) and volatile organic compounds <br /> using EPA Test Method 8260B, <br />