ARCHIVED REPORTS_XR0007892 - Laserfiche WebLink

Home Browse Search

' locations, the impermeable nature of the soil did not allow gas to be extracted. For this reason, the soil gas probe was pushed one to two feet deeper and ground water samples were extracted. Soil gas was extracted at depths of 3 feet and 4 feet at locations E and F, respectively Ground water samples were collected at depths t ranging between 7 and 13 feet (at locations A through F, H, I, K, M, and N) The soil gas and ground water samples collected were analyzed for TPH and BTEX. tAfter completion of the soil gas survey, Kleinfelder drilled and sampled three shallow soil borings (designated B-1 through B-3 on Figure 4-1). The soil borings were drilled to an approximate depth of ' 7.5 feet, and soil samples were collected at depths of 1.5, 4.5, and 7.5 feet. The soil sample from the 7 5-foot depth interval from each boring was analyzed for TPH, BTEX, and organic lead. Kleinfelder also installed three monitoring wells at the site (designated MW-1 through MW-3 on Figure 4-1). Borings MW-1 and MW-3 were drilled to a total depth of 25 feet, and boring MW-2 was terminated at a depth of 26 feet. No soil samples were collected from the monitoring well bonngs. All three wells were constructed using ' 2-inch diameter PVC casing with twenty-foot long screens. Ground water was first encountered at a depth of approximately 9 feet bgs in borings MW-1 and MW-2 and at a depth of 14 feet bgs in boring MW-3. Ground water samples collected from all three wells were analyzed for TPH, BTEX, and organic lead. The investigation activities by HIeinfelder characterized the site- specific hydrogeologic setting and partially characterized the extent and occurrence of the release. The results of soil and ground water sample analyses performed for Kleinfelder are summarized in ' Table 4-1, and the entire Kleinfelder report is provided in Appendix G. 1 ERM-West Investigation ' ERM-West was retained by Catellus Development Corporation in April 1991 to complete additional investigation activities at Site #1 and to assess the need for remediation. The activities completed by ERM-West consisted of constructing two additional monitoring wells. ' These wells were located within and hydraulically downgradient of the tank site (designated MW-4 and MW-5 on Figure 4-1). ' Monitoring well bonngs MW-4 and MW-5 were advanced to a depth of 30 feet bgs and sampled at 5 foot intervals. The wells were constructed of 2-inch diameter PVC, and the well screens were set at ' a depth interval of approximately 10 to 15 feet bgs. Ground water was first encountered in both borings at a depth of approximately 6.5 feet 4-2