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CeoCogual?ec(rirics 2nc Page 2 Soil,i Groundwater Investigation Report J M Equipment Project No 507 2 July 5, 2001 i1 monitoring wells, two hand borings to 15 feet below grade surface (bgs), three soil borings advanced to 30 feet bgs, and one deep boring to 70 feet bgs The three new wells, MW-4 through MW-6, and five existing wells have been monitored quarterly since January 2000 The data indicates that a significant gasoline plume is present in groundwater at the site ' 2.0 SCOPE OF INVESTIGATION The puipose of this work was to further investigate the lateral and vertical extent of soil and gioundwater contamination 2.1 Soil Boi ing Installation A monitoring well pen-nit was secured from San Joaquin County and the agency was notified 48 hours prior to commencing work The subsurface was cleared of underground utilities by notifying Underground Service Alert and by consulting with the property owner Shallow Soil Borings 1n an effoit to define the lateral extent of petroleum hydiocarbons, three (3) soil borings, MW-7, MW-10 and SB-6 were advanced The borings were Iocated approximately 200 feet i southwest, 150 feet northwest and 100 feet west of, respectively, the loaner UST location (see Figure 2) Borings MW-7 and MW-10 were conveited into monitoring wells The soil borings were drilled as follows o MW-7 and MW-10 were drilled using an 8-inch outside diameter (o d ), continuous flight, hollow stem augei owned and operated by V&W Drilling (C57# 720904) The borings were drilled to a total depth of 30 feet bgs Soil samples were collected as desci ibed in ,Section 2 1 1 These borings were converted into 2-inch diametei monitoi ing wells The soil boring for SB-6 was drilled to a depth of 35 feet bgs with an 8-inch o d , continuous flight, hollow stein auger as above The drilling continued beyond thirty feet due to flowing sand conditions which precluded sampling at that depth Soil ' samples were collected as desci ibed in Section 2 1 1 Deep Soil Bonn ' To define the vertical extent of petroleum hydrocai bons, one (1) soil boring, MW-109 was advanced to 80 feet bgs in the location of the foriner UST (see Figure 2) Soil samples were collected as described in Section 2 1 1 This boring was converted to a discretely screened deep monitoring well Boring SB-6 was closed by pressure grouting a neat cement grout though a tremie tube The grout was brought to 6" below ground surface and allowed to mushroom The hole was then covered with i oad base material Soil cuttings were placed on plastic sheeting and covered The drilling decontamination water was placed in a DOT-17 55-gallon drum and placed alongside the soil pile until disposal can be arranged