ARCHIVED REPORTS XR0004316 - Laserfiche WebLink

Home Browse Search

Report on Additional Site Assessment and First Quarter 2000 Monitoring and Sampling Report 1 • 7-Eleven Inc Store#19976 1399 N Main St Manteca California Februaa 4 2000 10 INTRODUCTION This report is submitted by IT Corporation to summarize the results of site assessment conducted at the 7-Eleven Inc , Store No 19976, located at 1399 N Main Street, in Manteca, California (Figures 1 through 3) The scope of work for the site assessment included the installation of one additional groundwater monitoring well, collection of soil and groundwater samples, and preparation of this report summarizing the methods and results of the work performed The work was completed as outlined in IT Corporation's October 18, 1999, workplan prepared as requested and approved by the San Joaquin County Public Health Services (SJCPHS), in their August 16, 1999, letter I The work scope described in this report was completed at the site on December 26, 1999 Quarterly groundwater monitoring and sampling was completed on January 24, 2000 The summary of site assessment data indicates plume delineation is adequate, pending changes in existing groundwater monitoring analytical data trends No further assessment is considered to be warranted at this time �s ' 20 BACKGROUND Underground storage tank replacement and associated soil sampling activities were conducted in September 1996 Five underground storage tank pit samples were collected on September 19, 1999, one from beneath each end of the three USTs at 15 feet below grade(except for the north end of the central tank, which was under an excavation stockpile) Sample analysis for benzene, toluene, ethylbenzene, and total xylenes (BTEX), methyl-tert-butyl-ether(MTBE), total petroleum hydrocarbons as gasoline (TPH-G) (EPA methods 8020/modified 8015), total lead (EPA method 6010), and confirmation sampling for MTBE by EPA method 8260 indicated the presence of hydrocarbons in levels of up to 0 93 milligrams per kilogram (mg/kg) benzene, 220 mg/kg TPH-G, and 0 35 mg/kg MTBE (EPA ' Method 8260) (Table 1) The tank pit was overexcavated slightly to accomodate the new underground storage tanks, which were installed in the old tank pit (Figure 2), and post-excavation samples collected on September 20, 1999, were largely non-detectable (Table 1) 1 19976 35A