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�.• 21 September 2000 <br /> ..r AGE-NC Project No. 97-0360 <br /> Page 3 of S <br /> ofMines and Geology, 1977). The Modesto,Riverbank and Turlock Lake Formations and overlying <br /> Recent alluvium are the principal sources of domestic ground water in the 13,500-square mile San <br /> Joaquin Valley Ground Water Basin(Basin 5-22). <br /> 2.5. GROUND WATER DEPTH AND FLOW DIRECTION <br /> ... Based on the San Joaquin County Flood Control District and Water Conservation District Lines of <br /> Equal Depth of Water Wells Fall 1998 map,the estimated depth to ground water in the vicinity of <br /> the site is S to 12 feet below surface grade (bsg). <br /> 16. <br /> Based upon data obtained from nearby sites, the prevailing ground water flow direction in the <br /> vicinity of the site is estimated to be southwest. However, flow direction may be both locally and <br /> seasonably variable. <br /> `a 3.0. PROCEDURES <br /> On 13 July 2000, eight soil probe borings (P1 through P8) were advanced at the site as part of <br /> assessment activities related to the four former USTs. The field work was conducted as outlined in <br /> the PHS-EHD-approved work plan dated 07 April 2000. <br /> 3.1. DRILLING ACTIVITIES <br /> Soil probe borings PI through PS were advanced utilizing a van-mounted Geoprobe 5400 equipped <br /> with 1.125-inch diameter probe rods with an attached 2.15-inch diameter soil sampler,using"direct <br /> push"technology.Soil probe boring P 1 was advanced vertically to a depth of 25 feet bsg;P2 through <br /> P8 were advanced to 20 feet bsg. <br /> 3.1.1. Soil Sample Collection <br /> ti- Discrete soil samples were collected at 5-foot intervals,beginning at 5 feet bsg,to total depth of each <br /> boring. Soil samples were collected using a Geoprobe soil sampling assembly loaded with four pre- <br /> cleaned 1.125-inch by 6-inch brass sleeves. Soil samples were preserved by covering both ends of <br /> the brass sleeve with Teflon sheets,capping,and sealing with tape. Each sample sleeve was labeled <br /> with soil probe boring location, depth, time, date and sampler's initials. <br /> f <br /> Advanced GcoEnviranmental,Inc. <br /> i.w <br />