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r.umltrtundts. The TARIA" (Ines not include rue:h Information tilt tilt! detecti011 IinO% tit whir.h Othrrr cnr;jpoulift n were) not detected. Tho full text of the Inhoratury report will hr, found In Suction Four or thin rr.port. GENERAL ADVISORY 01; POSITIVE RVISU1.TS Though our firm 11VOciali:00 in sampling, monitoring ntrd tiocumentt►tion, rather thnn Interpretation and remediation, we have been asked by the nnKinrr:ring staff of the Regiatsnl Water quality Control Board to Include In our reportu ars advitiory arction outlining tile, general type of nddttional a+:tions which may he required when contamination it; found. 'thin advinory in ;lot intended to characterize conditionn at this particular site or replace tits nervicen of a consulting firm specinlizing ill the inve sitigntion, characterization and remediation of touch conditiorrn tit' may exist. Rather, it its intended to mlly r, youpm- that Ktsyouch tire i ret onni action"contacted bytn"Y be one of tilesiinter tete d regulatoryeven thoUgh mr. tiro( osis}' elapscr before y tsgencies, {rs R,!gion l (which is regulated by the San I=rnnciticn It,?gsarsttl Water quality Control Hoard,) the thresholds tire readily definvd in the board's ptsblicution, ruidr__. Iin+�K For ,Ndelrctetdn�r H�tr1 t.rnkt�. ACdordis1K to this document. soil which hiss leers than 100 parts per million total petroleum reel hydrocarbon (Tp11) contriminution dont: not generally require, immediate additional action. Board engineers emplinuize that this doass not mean that some action migist not be required in the future. Still, tho Hite is assigned a low Priority unless it is situated in an area rf high h}•drageoingic concern. The detection of more than 100 ppm TPII in the native soil beneath a tank is generally considered grounds; for requiring tin additional investigation in the form of soil borings and Inutaltation of at least one groundwater monitoring well followed by periodic monitoring. The detection of 100U ppm TPI, is usually viewed by the Board as nn unacceptable lr'vel Of fuel saturation which will mandate excavation of the effected ground down, to the furthest practicable reach of conventional excavating machinery Irfollowed by soil boringn and installation of groundwater monitoring Other regions uhe different standards for determining when a groundwater Investigation will be required. For example benzene is often used in lieu of TPII. Even very low levels of benzene are often seen as grounds for requiring a subsurface investigution. This criteria may be relaxed or stiffened depending an the location ofthesite f eandoroundwater theoconcf.- ntrsttierent onsuof benzene systems, the depth to water, type of soil involved. The above standards apply Only to fuels. When samples taken in connection with n waste oil tank or a solvent tank are found to contain even small amounts of any of the FPA priority pollutantB (such as TCE, PCE, ACE etc iwhich-are defected b>, EPri- methodts-$illi},-Stl2L1r and..B24t1)_.more.stringent __.._._ __...__ ..._ ..-------- -- ----..._.._...-- standards are often applied. in these cases, sail borings and monitoring well installation may be required if there is any detectable amount of any of Sompling Report 88057-C-1 Chevron 1918 SHGTION TWO/page 12