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i.,, ,<• .-('y„ ,r;., SFE n f, L3w •Ff- ''.'r -"�,. nC 'h,. A Fti� s; a - !+ r. t n ,4$ �v- '4._:�' .ret - t r`i c ;.� i+ a r fi Shu arck s�va,.�s ��. �..• �w ,�•� �^ .„�� Sx•�� ,r�,� ti �u rk a S June 25, 1991 ARCO Service Station 760, Lodi, California On June 18, 1991, we collected soil samples 5-13-TI through 5-13-T3 from beneath The north and south ends of tate former tanks at 13 feet below grade. Two soil samples(5-6-1N and 5-10-2N) were c,)Ilected from the north sidewall to evaluate residual hydrocarbon concentrations remaining in the soil. One sample was collected from the south sidewall(S- 10-15) to dr,ineate soil with residual hydrocarbons in that direction because a soil boring was not drilled at tho southern end of the tank cavity during the October 1910 investigation. Soil samples were also collected in the proposed tank cavity at 12 feet below grade(samples 5-12-T4 through 5-12-7.7). On June 19, 1991, a 55(1-gallon tivastw-aiE tank was discovered during excavation of the e proposed tank cavity(labeled Tank T8 on Plate 2). We collected a sample of the liquid from inside the tank (W-6-TS). On .Tune 21, 1991. soil samples 5-12-T6N and S-12-T6S wese collected from approximately 12feet below grade at the northern and southern limits of the proposed tangy,cavity. 'I' T-8" -8 r.'as also removed on that date,and a soil sample (5-11-T8) i was collected from 12 feet below' grade under the former tank. w Laboratory Analyses fSoil samples collected under tants Tl through '3 were analyzed for total petroleum hydrocarbons as gasoline (TPHg) using Environmental Protection Agency(EPA) modified Method 8015.benzene,toluene,ethyibenzene,and total xylene isomers(BTEX)using LFA Method 8020, 12;dibromethane(EDB)using EPA Method 8240,and total lead using EPA Method 6010. Soil samples collected from the Bottom of the proposed tank cavity were analyzed for TPHg and BTEX. The soil sample:collected under tank T-8 was analyzed for 1 'TPHg, BTEX, total petroleum hydrocarbons as diesel (TPHd) using EPA Method 8015, total oil and grease(TOG)using Standard Method SS20e and f,volatile organic compounds (VOC's) using EPA Method 8010,and total metals using EPA Method 6010 for cadmium, chromium III,chromium VI.nickel, lead and zinc. Copies of the Chain of Custody Record ' and laboratory reports are attached to this letter. Laboratory Results Results of analyses of the soil samples collected under former tanks T1 through T3 and the sidewalls of the former tank cavity are presented in TaLle 1. Residual hydrocarbon concentrations remaining in place in the former tank cavity range from 0.52 to 250 parte per million TPHg and from 0.01 to 18 ppm BTEX. Concentrations of EDB and total lead were a below detection limits. g i J 0624 cm 2 �aaa s j s }