ARCHIVED REPORTS XR0001184 - Laserfiche WebLink

Home Browse Search

r Mr Don Rodgers Project 2613-100 01 . June 4, 1998 Page 2 Between September 17 and October 11, 1996, Pinnacle observed the drilling of six soil borings (BAR through B-6R) One soil boring was converted to morutoring well MW-1R, three soli borings were converted to dual completion vapor extraction wells VW-1 through VW-3, and one soli boring was converted to a single vapor extraction well VW-4 (EMCON, Preliminary Investigation and Evaluation Report, February 5, 1997) The results of this investigation indicated the following • The majority of residual hydrocarbons were detected in the vicinity of the former USTs and dispenser islands Residual hydrocarbons were detected in each boring, except from soil samples collected from boring B-6R The highest concentrations were detected approximately 10 feet below ground surface (bgs) near the former USTs Total oil and grease was detected in the soil sample collected near the former UST cavity (located near the building) at a concentration of 10,000 parts per million Polychlorinated bi-phenyls, TPHD, and chlorinated hydrocarbons were below laboratory detection limits in all soil samples analyzed from soil borings B-2R and B-6R • Groundwater was encountered at approximately 31 to 38 feet bgs On September 30, 1996, static groundwater was measured at 26 44 feet bgs in monitoring • well MW-1R Groundwater elevation is consistent with groundwater elevations measured at adjacent properties • TPHG, benzene, toluene, ethylbenzene, and total xylene (BTEX) isomers, and methyl tert-butyl ether (MTBE) compounds were detected in monitoring well MW-1R TPHG and benzene were detected at concentrations of 33,000 parts per billion (ppb) and 1,400 ppb, respectively MTBE was detected at a concentration of 550 ppb GROUNDWATER MONITORING: FIRST QUARTER 1998 On March 20, 1998, an EMCON technician was on site to measure depth to groundwater and collect a groundwater sample from well MW-1R for subjective and laboratory analyses Floating product was not observed in groundwater monitoring well MW-IR (see Table 1 and Appendix A) Pinnacle used these data to evaluate changes in concentrations of dissolved gasoline hydrocarbons in the groundwater EMCON's sampling and analysis procedures are presented in Appendix B A groundwater sample was collected from monitoring well MWAR and was analyzed at Sequoia Analytical in Sacramento, Cahforma The groundwater sample was analyzed for TPHG using U S Environmental Protection Agency (USEPA) Modified Methods 8015, and for BTEX and MTBE using USEPA Methods 8020 and 8020A Modified, respectively In addition, per the California Regional Water Quality Control Board, Central Valley Region, requirements, the groundwater sample was analyzed for the oxygenates tertiary butanol, MTBE, di-isopropyl ether (DIPE), ethyl SAON\PJ2\2613\26131000 3AB-9Vba=s 1 Alsw-& Rev 0 6/4/98