ARCHIVED REPORTS_XR0001991 - Laserfiche WebLink

Home Browse Search

June 26, 1992 ARCO Service Station No. 549, Stockton, California i We collected soil samples from the soil borings and identified them using visual and manual methods and classified according to the Unified Soil Classification System (Plate 3). Descriptions of the materials encountered are presented in the Logs of Borings (Plates 4 through 25). During sampling, a photoionization detector was used to characterize the relative levels of hydrocarbon vapors emitted by soil samples. Readings recorded in the field are shown on the Logs of Borings. • The total depth of the soil borings ranged from 40 to 65 feet below grade.CGF6Wdd water ,was first encountered^at approximately 48 feet below grade. The sediments encountered generally consist of fine- to medium-grained sand, silt, and a trace of clay. 0 Soil cuttings generated during drilling were stockpiled on and covered with plastic. Four soil samples were collected from the stockpiled soil and submitted to the analytical ` . laboratory to be composited into one sample and analyzed. After the composite soil sample was analyzed, laboratory results were forwarded to ARCO, and at the request of ARCO, to Erickson Trucking of Richmond, California. It is our understanding that ARCO and Erickson Trucking coordinated the removal of the stockpiled soil. S Monitoring Well Construction On October 14 through 18, 1991, Westex constructed monitoring wells MW71 through MW-4 in borings B-6 through B-9, respectively. Monitoring wells were constructed to evaluate the ground-water flow direction and whether hydrocarbons were present in ground water near suspected sources of hydrocarbons and at the margins of the site. The locations of the monitoring wells are shown on Plate 2. Details of well construction are described in Appendix A. and the construction details of individual wells are depicted on Plates 4 through 25. • 5 30004-a f