ARCHIVED REPORTS XR0010492 - Laserfiche WebLink

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' of the excavation indicated that gasoline constituents remained in the soil at relatively low levels in the southwestern portion of the floor and sidewalls (Attachment A) In October 1990, William J Hunter& Associates (Hunter) supervised a subsurface investigation to explore the extent of contamination at the site Four soil borings (B-1 through B-4) were drilled at the site, and one soil boring (B-5) was drilled on the adjacent property owned by ' Hammertown Partners (Hammertown) to depths of approximately 40 feet bgs Gasoline constituents were detected in borings B-1, B-2, and B-5 at depths of approximately 25, 30, and 25 feet bgs, respectively No gasoline constituents were detected in soil borings B-3 and B-4 ' additional soil borings NBH-1 through NBH-3 were drilled at the site and In April 1992, three addit o g { g ) ' three additional soil borings (HBH-1 through HBH-3) were drilled on the Hammertown site to approximately 36 5 feet bgs Soil samples collected from the borings were analyzed for BTEX only, samples were not analyzed for TPHg BTEX were not detected in borings NBH-1 through ' NBH-3, HBH-1, and HBH-3 BTEX constituents were detected in boring HBH-2 at depths of 261h and 311/2 feet bgs The limits of soil contamination were defined by these soil borings, except in a southerly direction on the Hammertown property ' In August 1992, three additional soil borings (HBH-4 through HBH-6) were drilled to a depth of approximately 40 feet bgs at the adjacent Hammertown property site Toluene was detected ' in the three borings at approximately 40 feet bgs at concentrations ranging from 0 013 to 0 022 ppm BEX were not detected in the borings In January 1994, one additional soil boring (TB-1) was drilled at the site, and one additional soil boring (TB-2) on the Hammertown property The soil borings were drilled to approximately 71 feet bgs to first encountered groundwater Groundwater samples were collected using a ' Hydropunch''"r sampler advanced to a depth of approximately 75 feet bgs TPHg and BTEX were not detected in soil and groundwater samples collected from the borings ' In a letter dated May 24, 1994 San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) requested two additional soil borings be drilled in order to further ' evaluate soil contaminant concentrations previously detected in the area of the former UST in sidewall sample SW-2W and in offsite soil boring B-5 PHS/EHD stated that if soil samples from the two requested additional soil borings demonstrated significant reduction in gasoline ' concentrations since 1990, and if the mass/volume of gasoline remaining in the soil could be calculated, then PHSIEHD would reconsider the site for closure ' Therefore, in July 1994 Hunter drilled two additional soil borings (Location A and Location B), to depths of approximately 41 feet bgs, in the vicinity of previously drilled soil boring B-5 and former UST excavation sidewall sample SW-2W, respectively Analytical results of soil samples ' collected during this phase of work indicated that gasoline constituents in both locations had decreased at least one order of magnitude since the initial investigation Hunter concluded that the vertical and horizontal extent of soil contamination had been defined, that groundwater had ' not been impacted, and that the levels of residual gasoline contamination had decreased groundulnom=Xsumrepor 95 2