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'§MO 'tom „P-ear ,parr it S°`s'' _ .. « r. i 2.6 UNDCRGKOUND STORAGC TANKS BecaUze the service statim hacl been demolished in l cbruary 1988 and tlae duce underground stonage tatsis in use at that time were rcmavcd,additional underground sto:agc tanks were not anticipated. However,as moni(oring well MWS was collared,the auger met early refusal at a depth of 2 feet. An apparently thick,plate/will of steel was IK� encountered. Closer inspetuon revealed a liquid of unknown eomposidon beneath the steel v plate. An OVM scan In the shallow hole registered elevated levels of h)drocwbons. Mic possible existence of rt storage tank or puntrurt of a sewcr Lina was Lmntcdiauly reported to Chevron. The liquid was sampled and subtritted for chemical analysis as an unkn0M r liquid to Pace Ubaratories, The EPA method 8015 analysis indicated a TPI l concentration of 89 peen:. The inquiry with Chevron produced a Recotruneaded Facilities List (Appendix D).an Internal Chevron document.that Indicated b tanks cAsted onsite 10 March 1953. Apparently,some of these tanks had not been rernoved during previous remodelling of thtt station. The hole to the steel was covered knit a plastic bucket that wis covered with soil In order to prevent the shaltow hole from pncscnung a hazard. EA returned to the site of foorrncr Chevron 5S 9-1918 on 15 November 1988 to direct and observe the excavation to expose the supectcd tankA wArer line. A 550 gallon,steel storage tank was exposed,located as Indicated on Figure 3. The soil around the tank wets excavated to a depth of approximately 5 feet below ground surface to expose the full size of the tank. In doing so,old steel product lines were discovered and followed to determine if they might still be connected to other storage teaks. The lines extended approxitr a0y,45 feet funhcr north where rxo nxxe steel tanks were discovered. The larger of the tanks was esdmated to be appsoaimmcly,4400 gallons in capacity and the snsall-er tsnk was estimated to be 3000 gallons. Each tactic had been abandoned inplace by tipping holes in the togs of the tank anti backfilling with soil. The OVM did not detect hydrocarbons in the air either above or within the teethes. The locxdons of flat:tanks were sketched In the licld on a bluelin,radluses%tre pulled from kkntirWge Irtndtrxks wA refer teed back on the biuckm The open hole in the 550 -------------_-----------------...-_.._-._gallop tulle which s>'aulned tete unknown Equicd was co%vW with pUstic sheedrtg after ataaothcr satrnple of the ljVW ways ooh=ed. AU three tanks w to npouily reb=W%ith . soil to saute the aaatg from tampaing vA to prevent the c madoan of in undesired Word wWk the neocssmy pelts wacre rpp:Iod for by OU Fquipm m Service!m, 7