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Ga"Y "�� x'..»*.. :-..:`.. s';;7 t...a-:=- r}'" �".^ ti- -s ,.a':?�ar:.. Y-... xY?ad .�' � s sash a,.a t o a 14; 9 r : T q _ 5 ` the fill pipe and the corroup.)ndina opl-rmite rnd of the lank rind obtaining n nnrgilq� from ttie bnrkfill/nntive oloil interfnce or n ati art dinlnnrr bolo w ttip Intortnco. In the cutir of tnnkn beau thnn ),ON gullonx in cnpncity, only one n»mple from bontinth thr tank in required. A short dintancti h+nn bran defined by Region 2 Board nnginr^rrt na not gr+antoir than twenty-four inc:hrn below the bnclifill/native moil interface and In generally tAken to be nn2 foot below the the backfill/nntive nail intewrfaco. Thin moil iq brought up in the bnrkhoe bucket. A abovr.l or trowel is noted to cut nwny surface nail and backfill nnterinl which may hnvn brrn included in the huckal, send the pample is taken by puwhing or driving a bratta n.nmpies liner into the newly exposed moil from the dranignated depth and location. Additiunol eJnrificationat by Region 2 hoard r.ngince:rn have indicated that wlien there is an obvioun difference- In the ralntive conutmination or soil brought up from the interface depth, then it it: the relatively more contliminated &oil that should be selected for incluaion in thn anmple. ELECTIVE EXPLORATORY SAMPIX,: Thin type of anmplintg employs the same #Ample collection and handling procedurion an are used in atAndurd R QCI3 interface sampling, but the nail in typically obtained at a greater depth or from a position that In internily offtmt froth the intertnco location. STOCKPILE SURVEY MODIFIED IIAAQMD PROTOCOL: Thin namplinx follows a &urvcY pattern, but user+ it modified DAAQMD Protocol for namplinir 4tockpiisa of mt,tnrinl that havo been newly removed from a tank pit excnvntinn. Thin protocol calla for a diacretee snmple, container to be collected for overy 12.5 cable yards of material. The survey Includea oppo#ite sides of the _ &teckpile. Strict obeervance of the BAAQMD protocol (for Purponon of i evaluating the levels of lual vapor likely to be discharged from a stockpile) calls for Inclusion of the surfaces material in the bratty liner which is 3 driven into the pile at a right angle Ito the angle of repose) until the ! liner Is full. Unless specifically tucked to follow the IIAAQMD protocol, our perannnel routinely modify the procedure to exclude the surface soil t,nd collect soil from a depth of eight to eighteen incites. White thin prejudiced the simple in the direction of yielding higher results than would a strict 8AAQ1kID sample, It in more representative of the levels of fuel hydrocarbons present in the will and is not likely to mislead the client or contractor Into offhauling or backfilling with soil stockpiles that are rolutivrly clean at the surface, but unacceptably contaminated through the remainder of their volume. • SAMPLE CON`TAINC�ftS Our firm uecs now sample containers of the type specified by either EPA or the RWQCB for the collection of snmples at silos whore underground storage tanks are involved. hater samples are contained In 40 ml volatile organic analysis vials (VOA%) when analysis for gasoline and similar light volatile compounds is Intended. Thatie containers are prepared according to EPA SN 1146 and will-contain a snsall-amount-of-preservative When the anatyuis-in-for 'TPH --- -- an gasoline or EPA 602, Vials intruded for EPA 601 analysis and EPA 624 GOMIS procedures etre not preserved. Closure is accomplished with an open headed (syringo accessible) pinntic ,screw cap brought down on top of a Teflon (send Sampling Report 88057-C-1 Chevron 1818 SECTION TWO/page 9