ARCHIVED REPORTS_XR0012557 - Laserfiche WebLink

Home Browse Search

�Z �.;� '' s 1. r.. Problem Assessment Report December 5, 1989 USA Petroleum Station No. 65, Lodi, California AGS 87050-3 toward the southeast because a municipal well is located approximately 1,500 feet southeast 1 of the site(Applied GeoSystents, Proposed Work-Elan for Assessment �f$o€I and Ground- Vate o tami anon at A talion No.65 2500'West Lodi Avenue Lodi,Ca}ifoniia, No. 87050-3W, November 4, 1988). After we installed wells ..MW-4 and MW-5, USA requested us to obtain permits for two'additional offsite wells (MW-6 and MW-7) to further delineate the limits of groundwater contamination. i3?i' rd6 in ssessrn n Repoit risese"tits out"firitfiir►gs on'tlie lateral-extent of-hydrocarbon cai4a_rftanafidit;arrc!`provides;atldiiional+in#r�taraatiQn necessary„to.develop a,remediation-plan ,JOi+&site Ibe work performed and not previously reported in this investigation included y. (1)drilling four soil borings offsite;2)collecting soil samples and classifying them according to the Unified Soil CIassification System; (3)installing four ground-water monitoring wells .. in the borings; (4) sampling groand wafer from seven monitoring wells at the site; {S) surveying the elevations of the wells; (6) performing bailer tests to obtain a preliminary f estimate of the transmissivity and hydraulic conductivity of (lie aquifer; (7) evaluating the groundwater flow direction at the time of sampling; 8) evaluating the zero line for contamination; and 9) assessing remediation alternatives. Ground water monitoring well MW-4 was drilled and installed on January 17, 1989; well MW-5 was drilled and installed on January 18, 1989. At the request of USA, well MW-6 d rye was drilled and installed on February 23, 1989, and well MW-7 was drilled and installed on t March 28, 1989. Wells MW-6 and MW-7 were necessary in this phase of work to delineate the limits of ground-water contamination. Soil and ground-water samples were collected and sent to the Applied GeoSystems # analytical laboratory in Fremont, California. Tlie soil samples were analyzed for total petroleum hydrocarbons (TPH) as gasoline using modified Environmental Protection 1 Agency (EPA) Method 8015 and for benzene, toluene, ethylbenzene and total xylene isomers (BTEX) using EPA.Method 8020. Water samples were analyzed for TPH as” gasoline using modified EPA Method 8015 and BTEY using EPA Method 602. Laboratory results of soil samples collected from immediately above the ground-water surface in each boring indicate TPH as gasoline and BTEY constituents were below detection limits for the tests used. Laboratory analyses for ground-water samples indicated hydrocarbon contamination was present in water samples from wells MW-1 through MW- 4, and MVV-6. The highest concentration of TPH as gasoline detected is approximately 0.8 in well M 2 li gls sfFher+zen ce©ricer iliattOn 2tatectc IS t1'J27 parts n t+ir4. gievels of benzene in wells MW-S and MW-7 were below the detection limits for the tests used. Concentrations of toluene and ethylb�mzene are either below detection-limits-or-no-higher-than.0.005 - --- --- - -- ---- --- ppm-above detection.limits:-The }tighesi total x, xylene isomers concentration is 0.0024 ppm in well MW-3. d 17 {