Laserfiche WebLink
13 April 1993 <br /> (GeoAudit-1. 33) <br /> Page 2 of 5 <br /> Four additional groundwater wells (MW-6 through MW-9) were <br /> L installed by SCC in July 1990 to further define the extent of the <br /> dissolved hydrocarbon plume. Soil samples from 40 to 50 feet below <br /> ground surface from some of the pilot borings contained moderate <br /> levels of contamination which were attributed to the lateral <br />' migration of contaminants along the capillary fringe (BCC report <br /> dated July 1990) . <br />' The most recent investigation was conducted by PES. Four <br /> groundwater monitoring wells (MW-10 through MW-13) and one <br /> extraction well (EW-1) were installed by PES in May 1991. Similar <br /> to previous investigations, the highest level of contamination was <br />' encountered in MW-4 . PES also conducted an aquifer test on the <br /> extraction well EW--1. An extraction rate of 2 gallons per minute <br /> was estimated (PES Problem Assessment Report, dated 31 July 1991) . <br /> I <br /> SCOPE OF WORK <br /> Soil contamination still remains undefined on the property. The C <br /> & A Order issued by the CVRWQCB requires that the soil <br /> contamination be completely assessed for the purpose of <br /> implementing a remediation program. <br /> GeoAudit proposes to drill a minimum of (6) soil borings to 10 feet <br />' below detectable contamination (using field methods) . Where <br /> contamination is encountered, the boring will be� completed as a 4- <br /> inch diameter vadose zone remediation well, screened in the <br />' contaminated interval(s) . Should contamination extend to <br /> groundwater the borings will be grouted to 10 feet above <br /> groundwater and completed as described above. <br />' The soil borings will be drilled in the area of the former <br /> underground storage tanks (UST' s) and the dispenser island. If <br /> significant contamination is encountered during drilling, <br />' additional borings may be required to fully assess the lateral <br /> extent of contamination. We would then step--out (approximately 20 <br /> feet) and drill additional borings. <br />' An off-site boring may be drilled north of MW-5. The CVRWQCB has <br /> also requested that GLDM consider installing an additional <br /> groundwater monitoring well (MW--14) north and up-gradient of MW-6. <br />' Provisions for this monitoring well will be made in this work plan <br /> and the well may be installed some time in the future. <br /> 1 <br />