ARCHIVED REPORTS_XR0002403 - Laserfiche WebLink

Home Browse Search

Sod Excavation and Second Quarter Past-Treatment Monitoring and Sampling Report 1 The Southland Corporation,Store#20304,455 Grant Line Road,Tracy,CA June 9,1998 1,0 INTRODUCTION On behalf of the Southland Corporation (Southland), Fluor Daniel GTI, Inc (Fluor Daniel GTI)submits this Soil Excavation and Second Quarter Monitoring and Sampling Report to summarize sod excavation and groundwater monitoring and sampling at Southland Store No 20304, located at 455 Grant Line Road in Tracy,California (Figures 1,2 and 3) The scope of work included 1)destruction of three groundwater monitoring wells(MW-8, MW-9, and MW-10)and one groundwater extraction well (GWE-3) in the proposed area of soil excavation 2) grouting of all groundwater extraction and vapor extraction wells associated with the treatment system at the site 3) excavation,transportation, and disposal of approximately 270 cubic yards of hydrocarbon-impacted soil 4) backfill and compaction of the excavation, and 5) Installation of one groundwater monitoring well (MW-16)to provide source-area post-remediation monitoring The work was designed to fulfill the requirements of the San Joaquin County Public Health Services(SJCPHS) If dissolved hydrocarbon levels In the remediated area decline during the next sic months,site closure will be requested from the SJCPHS The work described in this report was completed at the site between April 27 and May 15, 1998 All work was performed in accordance with Fluor Daniel GTI's Remedial Action Plan for Soil Excavation,dated January 26, 1998,which was approved by the SJCPHS prior to field work notification . 11 Background The site is located at the northwest corner of Grant Line Road and Buthmann Avenue intersection, and is currently in operation as a 7-Eleven convenience store with no gasoline dispensing facilities The facility was constructed in October 1978 with underground storage tanks(USTs)and associated piping located in the center of the site On October 27,1986,the UST's were taken permanently out of service after one of the tanks faded a routine tightness test From December 1986 to September 1988, Harding Lawson Associates(HLA) installed monitoring wells MWA through MW-15,and exploratory probes P-1 through P-8(Figure 2) Highest total petroleum hydrocarbons-as-gasoline(TPH-G) concentrations in soil were detected in boring P-4 at 4 7 feet below ground surface (BGS) at 1,400 milligrams per kilogram (mg/kg), and highest benzene was detected In P-8 at 0 098 mg/kg (Table 2) In 1990, HLA proposed the Installation of a soil vapor and groundwater extraction system, and conducted a short-term pump test indicating well yields of 20 to 40 gallons per minute On May 11, 1993, Groundwater Technology, Inc installed groundwater extraction well GWE-1 Benzene and TPH-G were detected in the soils from the well bore for the well at 2 7 mg/kg,and 280 mg/kg, respectively, at 8 feet BGS An extracted water discharge line was Installed to the storm drain in June 1995 prior to installing the remediation equipment in September 1995 Groundwater extraction from GWE-1 began in October 1995 The system was shut off in April 1996 because of low yield and Inability to generate a suffrcient cone of depression FLUOR DANIEL GTI 2a+aex.►pt 1�5_