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g*4"r)lk oil nd 4. Tho TARIX dr-A toot Inctudi- nuch 3jjr(Jj'jr1%tjL;jj AN tjj#' (191trCtit71l limitio; At which Miter erimpolindit io-:tore mit fIrto-t-terl. 71m full tett ;or the 'nbornlory rtrxirt will be fround tit Sechm 1,,,t;r of thi-t rer4rt. GENERAL ADVISORY 011 ;10!',ITIVV I?Pgtf[,T% Though our firm apprinlizos In namplitig, monitoring tind dcK1irrwnttiti4)n, ri:othrr thart Interpreltstlon and remediation, we have been asked by the eiwattlepring Ntaff of the Regionni Water Qunlity Control 114omr(i to inciide in wit, refk"rtt' an advisory section outlining the gnnoral typo. of tidditionul octiotot, oilch rtijiy be required when contamination ih found. Thin advipary im not intririded to characterize condit.10111i at this porticular isitt- or replace the :srrvicoft of f4 consulting firm topocinlizing in the hiveritigrotion, chni,ftcteritntion And romediallon of nuch conditions an mny exist. Rather, it its Intended to advinp you that much nd4fitionid actions may be required even though some time tray elapt-r before you are contacted by ant of the initirritted regulatory agencies. In Region 2 (which in rogulntwd by the San Francitica itrgtnntsi Wat.t,#- quality Control Board,) the thresholds are readily defined n the limird's publication. C.uidelinn for AAdrer-oLng flioj Len q. According to tail document, soli which hits ienh than JUD parts per million total Petroleum fuel hydrocarbon (TPII) contisminution do-,-n not generally rt.)q%jir(s immedinte additional action. board engineers omphasf:e that thin does. not mean that ranine action might not be required In the future. SUN. the site In assigned it low priority unletin it is aftwated in an arra of higlo hydrogsolcogir concern. The detection of mora than 100 ppri TPH in the native soil tw-no:%th a tank is considered grounds for reqttiring an additional investigation in the generally is form of &oil borings and Inattillation of at least one, groundwater nionitoring well followed by periodic monitoring. The detection of low pprr, TPH in usiunlly viewed by the Board as an unacceptable P!vel of fuel tvaturrition which will mandate excavultion of the, affected ground down to the lurtht-st practicable reach of conventional excavating machinery toll"ed by soil ttorings and installation of groundwnter monitoring wells. Other regions use different fitAndarda for determining whe-n a 1:roundwater investigation wilt be required. For example benivne is often uted in lieu of TPH. Even very low levels of benzene are often seen as gi-troun d?i for requiring a subsurface Investigation. This criteria may be relaxed or atirro.-ned depending on the location of the site In relation to different. groiindwater a>-stems, the depth to water. type of soft, and the concentrations of benzene involved. The above standards apply only to fut.-ts. When samples iunkesi to connection with a waste oil tank or it solvvot tank are found in cnirioLatin eves, small aniou-n-tititet-any of thisEP.1 pr urftyImllu anta itotic % as TUh, Pt-F.: Mc. which are detected by FPA inethods 6010, 8020, and 8240) mare otringent ht-midards are often appliod. It, these castes, Fail boringa and monitoring well ingtallation may bo required it there is tiny detectable timount of any of *L Sampling Plaport 89057-C-1 Chavron 1918 SL 'TION WO/page 12 J