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�r <br /> 27 September 1999 <br /> • AGE-NC Project No. 97-0327 <br /> Page 3 of 9 <br /> f Jackson-Hallenbeck-Stockton (JHS) association. The JHS soils are located within basins, and <br /> generally consist of moderate to poorly drained fine textured soils. The soils are generally derived <br /> r from both marine and non-marine sediment, and are generally formed in alluvium derived from <br /> mixed rock sources. <br /> The Modesto,Riverbank, Turlock Lake Formations and overlying recent alluvium are the principal <br /> source of domestic ground water in the 13,500 square-mile San Joaquin Valley Ground Water Basin <br /> (Basin 5-22). This basin is drained primarily by the San Joaquin River. The nearest surface water <br /> feature in the vicinity of the property is the Stockton Diverting Canal located approximately 2,500 <br /> feet north of the site. <br /> 2.5. GROUND WATER DEPTH AND GRADIENT <br /> Based on review of the Lines of Equal Depth to Groundwater Fall 1997 map published by the San <br /> Joaquin County Flood Control District and Water Conservation District(FCD&WCD),the estimated <br /> depth to ground water at the site is between 60 feet below surface grade (bsg). Review of the map <br /> Lines ofEqual Elevation of Groundwater Fall 1997(FCD&WCD)depicts the regional ground water <br /> flow direction towards the northeast. <br /> 3.0. PROCEDURES <br /> On 21 June 1999, four soil probe borings (P-6 through P-9) were advanced at the site as part of <br /> assessment activities related to the three former USTs. The field work was conducted as outlined in <br /> the PHS-EHD-approved work plan dated 07 August 1998. <br /> 1 ' <br /> DRILLING ACTIVITIES <br /> Soil probe borings P-6 through P-9 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 borings P-6 and P-7 were advanced vertically to a depth of 40 feet bsg; <br /> P-8 was advanced to.55 feet bsg; P-9 was advanced to 30 feet bsg (See Figure,2). <br /> 3.1.1. Soil Sample Collection <br />' Discrete soil samples were collected t - <br /> • p a 5 foot intervals, beginning at 15 feet bsg, to total depth of <br /> each boring. Soil samples were collected using.a Geoprobe soil sampling assembly loaded with four. <br /> Advanced Geounvironmento lne. <br /> 1 <br />