ARCHIVED REPORTS XR0001873 - Laserfiche WebLink

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Mr Kenneth Earnest Ultramar Inc May 10, 1994 Page 2 ' scope of Work Between February 1, and March 12, 1994, 16 soil borings were advanced to depths of 65 to 82 feet ' Soil samples were collected from each boring at approximately 5 foot intervals for classification and possible laboratory analysis Three of the borings were completed as ground water monitoring wells, one boring was completed as a ground water recovery well, and the remaining borings were completed as nested soil vapor extraction wells On March 16, 1994, reference marks at the tops of the well casings were surveyed and ground water elevations in the wells were measured Field methods used in this investigation are described in Enclosure A Locations of the wells are shown in Figure 2 Soil Borino Soils encountered during drilling were generally silt with fine grained sand from the surface to depths of approximately 20 to 30 feet, fine grained sand with silt to approximately 40 to 45 feet, clay with fine grained sand to approximately 55 to 60 feet, and discontinuous layers of mixed sand, silt, and clay to the maximum depth of drilling Ground water was present at a depth of approximately 67 feet below grade Geologic cross-sections illustrating the inferred stratigraphy of the site have been prepared A geologic cross-section location map is presented in Figure 3, and geologic cross-sections. le' A-A', B-B', and C-C' are presented in Figures 4 and 5 Soil boring logs containing detailed descriptions of the soil encountered and other information regarding the advancement of the borings are presented in Enclosure B ' Soil Sample Analytical Results Selected soil samples collected from each of the borings, and soil samples collected from the stockpiled drill cuttings were submitted for laboratory analysis of benzene, toluene, ethylbenzene, xylenes, total petroleum hydrocarbons (TPH) as gasoline, and TPH as diesel Two of the stockpile ' samples were also analyzed for concentrations of total lead and organic lead Soil sample analytical results are summarized in Table 1, and copies of the analytical laboratory reports are presented in Enclosure C ' Well Construction Three of the soil borings were completed as ground water monitoring wells MW-28, MW-29, and MW-30, one boring was completed as recovery well RW-2, and the remaining borings were completed as soil vapor extraction wells VEW-1 through VEW-12 Each vapor extraction well contains multiple casings extending to various depths All wells were constructed with ' flush-threaded, Schedule 40 PVC casing Well construction details are summarized in Table 2, and are individually illustrated in Enclosure D Ground Water Table Elevation Measurements Flow Direction and Hydraulic Gradient Each well at the site was checked for the presence of ground water on March 16, 1994 The depth to water ranged from 64 87 to 67 33 feet below the tops of the well casings The ground water table elevations recorded on March 16, 1994, are presented in Table 3 A water table contour map prepared using the ground water elevations recorded on March 16, 1994, is included as Figure 6