ARCHIVED REPORTS_XR0008499 - Laserfiche WebLink

Home Browse Search

1� HYDRO BMRONLMENTAL. TEDINOLOGIES,INC. . 3.0 RESULTS AND DISCUSSION 3.1 Site Stratigraphy Sediments encountered during this phase of drilling consisted of interbedded lean clay, lean clay with sand, sandy clay, clayey sand, silty sand and fine to medium grained sand from ground surface to approximately 35 feet below grade Lean clay, lean clay with sand and sandy clay with some fat clay and sandy silt was encountered from approximately 35 feet below grade to 90 feet below grade. The stratigraphy encountered during this phase of drilling is generally consistent with that encountered during the previous phase, with the exception that more silt was encountered previously Complete soil sample descriptions are presented on the Soil Boring Log and Well Construction Diagrams in Appendix C 3.2 Results of Soil Sample Analysis Neither TPHg nor BTEX were detected in concentrations exceeding the method detection limits in soil samples collected from borings MW-6, MW-7 and MW-8. A summary of soil sample analytical results is presented on Table 1 A copy of the laboratory reports and chain-of-custody forms are attached in Appendix E 3.3 Ground Water Gradient Ground water was initially encountered dunng drilling between 75.5 and 78 feet below grade. On December 9, 1993, the depth to ground water in each of the wells ranged from 73.51 to 74 09 feet below grade. Depth to water measurements and wellhead elevation data were used to calculate ground water elevation contours. These contours are shown on Figure 3, the Ground Water Contour Map Figure 3 shows the ground water flow to be towards the southwest at an approximate gradient of 0 0013 ft/ft (0 13%) 3.4 Results of Ground Water Sample Analysis TPHg was not detected in concentrations exceeding the method detection limits in ground water samples collected from monitoring wells MW-1, MW-5, MW-6 and MW-8 TPHg concentrations ranged from 59 parts per billion (ppb) in the ground water samples collected from both MW-4 and MW-7 to 550 ppb in the ground water samples collected from MW-3 Benzene was not detected in concentrations exceeding the method detection limits in ground water samples collected from monitoring wells MW-1, MW-6, MW-7 and MW-8. Benzene concentrations ranged from 11 ppb in the ground water sample collected from MW-5 to 270 ppb in the ground water sample from MW-3 A summary of ground water elevations and sample analytical results is presented on Table 2. Hydrocarbon concentrations are 4