Laserfiche WebLink
L 0 <br /> 07 April 1999 <br /> 0 AGE-NC Project No 98-0540 <br /> Page 2 of 9 <br /> by AGE <br /> 3 1 REVIEW OF HISTORIC REGIONAL DEPTH TO GROUND WATER MAPS <br /> Review of depth to ground water maps published by the San Joaquin County FIood Control and <br /> Water Conservation District dating back to 1971 indicates that historical ground water depths may <br /> have been as low as 80 feet below surface grade (bsg) near the site (Fall 1990) <br />' 3 2 ADVANCEMENT OF PROBE BORINGS <br /> On 25 January 1999, AGE advanced two soil probe borings at the site Probe boring P1 was <br /> advanced within the former UST excavation to a depth of 50 feet bsg Probe boring P2 was <br /> advanced immediately adjacent to the assumed former waste oil UST Samples were collected at <br /> five-foot intervals in each probe boring <br /> lie3 3 SOIL BORINGS AND MONITORING WELL INSTALLATION <br /> On 25 and 26 February 1999 and on 01, 02, 03, and 05 March 1999, AGE advanced five borings to <br /> approximately 80 feet bsg Three of the five borings were completed as groundwater monitoring <br /> wells Soil borings were advanced utilizing a truck-mounted drill rig equipped with 8-inch and 10- <br /> inch diameter hollow stem augers. The drill rig and two man crew were supplied by Cal-Nev Drilling <br /> of Rancho Cordova, California The soil boring/monitoring well locations are depicted in Figure 2 <br /> 3 3 1 Soil and Grab Groundwater Sample Collection <br />' Discrete soil samples were collected at 5-foot intervals, beginning at 30 feet bsg from soil borings <br /> B2, B3(MW-2), B4, and B5(MW-3) Soil samples were collected starting at 55 feet bsg in B I(MW- <br /> 1) Soil samples were collected utilizing a California split-spoon sampler loaded with 2- inch by 6- <br /> inch brass sleeves The sampler was driven by dropping a 140-pound weight from a height of 30 <br /> inches The number of blows required to drive each 6-inch interval of the sampler(blow counts)was <br /> recorded on boring logs by an AGE staff geologist <br /> ISoil samples were preserved by covering both ends of the second brass sleeve with Teflon sheets, <br /> capping and sealing with tape Each preserved sample sleeve was labeled with soil boring location, <br /> depth, time, date and sampler's initials and was stored in a chilled container under ice Selected soil <br /> • <br /> samples were logged on a chain-of custody, transported to a State of California Department of <br /> I <br /> Advanced GeoEnvironmenial,Inc <br /> I <br />