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06/03/1999 09 51 7078382323 GALLARDO AND ASSOC PAGE 05 • • Limited Soil and Groundwater Report-05!74199 Page 1 W astern o g&S r Ing Site Pro ect Nm 024.98 1.0 FXECUTWE SUMMARY ' dvanced five sax-inch diameter soil borings(B-1 [�March 23 and 24, 1999 Callatgrlo&Associates a through B-5) at 19256 N Highway 99 in Acampo, California (See attached Figure ] for Site ' Location Map). The soil bormgs were advanced at the request of the San Joaquin County Envromwntat Health Division(SdCEHD)for the propose of evaluating the condition of tbr soil and groundwater(i mTed)crossgradient and(inferred) downgxadient of the former UST cavity Based ' on the results ofthis mvestigahon, SJCEHD consider the site for ciosure;"�e� .a.4.1..0 Five exploratory soil bonvgs wore advanced to an approximate depth of 40 feet below grade surface ' (bgs) oil March 23 and 24, 1999(See attached Figure 2 for Borehole Site Map) After oomple-tmg the site investigation, a total of 20 soil samples and one groundwater "Grab" sample had been collected for laboratory analysis The soil samples were analyzed for the following petroleum constituents- the fuel Oxygenate Methyl Cert-Butyl Ether (MTBE), total petroleum ' hydrocarbons as diesel(TPH-d),total petroleum IWdrombons as kerosene(TPH-k), total petroleum hydrocarbons as gasohne (TPH-g), and the fuel constituents benzene,toluene, ethylbenzene, and xylenes (BTEX) The groundwater "Grab" sample was additionally atialy=d for the Fuel ' Oxygenates Di-isopropyl Ether(RIPE),Ethyl tert-Butyl Ether (ETBIE),MTBE,tert-Amyl Methyl Ether(TAME), and tert-Butanol(TA.), (See Tables 1 & 2 for an;a"cal results). Tthe mttoJdnRmg depth to groundwater ;vas not encountered during this investigation However, a shadow body of growidwater was detected at soil bormg B-4 at an approximate depth of 29 314 feet bgs and after an hour stabilized at approxunately 26 'fes bgs J�- ' Based on the data collected during this invesng'ation, Gallardo&Associates concludes That soil sampling resuhr cojWed from the f ive exploratory soli borings (B-1 through ES) indicate that ' the soil located beneath the properly at soil boring locations Br1,B-2, and B-4 has been impacted by moderate commntratiotrs of 1'PH-g, TPIiT-d, and TPH IG rhe vertical extent of the impacted sail appears to end at appr+axrmately 34 y feet bgs at b�vring B-.2, and approximately 29 �feet bgs ' at boring B-4. ffowever, veMcal definihon was not defined at baring B-J. The Impacted soil extended below the 40-foot maximum depth of the investigation as defined in the approved workplan. The horizontal extent of the impneted soil appears to be restricted to the area ' surrounding the 20,004 gallon UST's. No impacted soil was detected beneath soil boring B-5 located within the former diesel and gasoline UST's cavity. The highest concentrations of impacted soil appear to he centered beneath borings B-1 (TPH d at 30,000 ppm and TPh-k at ' 18,000 ppm)and B-2(TpH-d at 13,000 ppm and T,PH k at 11,000 ppm)at an appraximute depth of 29 3S feet bgs. In addition, analytical results eollectedfrom soil boring B-A indwate that concentrndons of TPH-d at J,g00 ppm and TPH--k at 1,700 ppm exp at an approximate depth i of 14 3/7 feet hgx The depth to the true water table was not encountemd during this investigation; however,a shallow perched water zone was detected beneath soil bort t&B-4 at an approximate depth of 29%feet bgs and has been impacted by eoxrcentrations TPH d, TR94, TPI)-g, and ' ,i�r ,wever,thins g�rottixd�vater was o11111 detected in soil boring B-4 The extent Of impact to this possibly perched groundwater could not terrrun urrn this limited xtz