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x. tcampl" from thr, bnckfill/native soli Inter#ace or a short distance below the Interfacet, In lhr- cafin of tanks lens than 1,000 gall on', in ropnc#ty, only one sample from beneath the tank is raquirod. A short distance has henn defined b3• Region 2 Board engincern no not greater than twenty-four Inches below the backfill/nntive soil interface and is gonerelly takero to be one tont below the the backfill/nntive soil Interface, Thin soil In brought up In the backhoe bucket. A shovel or truwal is used to cut away surface soil and backfill material which may have been included In the bucket, and the anmplr_ Is taken by pushing or driving a braes sample liner into the newly exposed Roll frLM the designated depth and location. Additional clarifications by Region 2 Board engineers have Indicated that when there In an obvious difference in the relative contamination of 0011 brought up from the Interface depth, than It #b the relatively more cor t.ernlnated soil that should be selected for Inclusion in the sample. SA.MPLP. CONTAINERS Our firm uses new samplo containers of the type specified by either EPA or y the RWQC© for the collevtlon of samples at sites where underground storage tanks are involved. Water samples are contained in 40 ml volatile organic analysis vials (VOAn) +risen analysis for gasoline and similar light volatile compounds is intended. These containers are prepared according to EPA Sig' 846 and will contain a small amount of preservative when the analysis is for TP1I as gasoline or EPA 602. Vials intended for EPA 601 analysis and EPA Gla GCmS i procedures are not preserved. Closure is accomplished with all open headed (syringe accessible) plastic screw cap brought down on 110p of a Teflon faced septum which Is used to Real the Sample without headapace. Water samples intended for seelivolatile and nonvolatile analysis such as total all and grease (TOG) and diesel ('TP1l NDF) are collected and transported in properly prepared new glass liter bottles. Dark amber glass is used in the m:•nufacturu • o. these battles to reduce any adverse effect on the sample by sunlight. Antimicrobial preservative may be added W the sample liquid if a prolonged holding time Is expected prior to analysis. Closers Is accomplished with a heavy plastic screw cap. 3 Sol) samples for volatile, semlvalatila and nonvolatile analyses are all r collected in , roperly prepared now brash liners which are 2 inches in diameter by 4 Inches In length. Closure Is accomplished with press fit plastic end caps -which are fitted to the open ends of brass tube after a sheet of aluminum toil in wrapped over the exposed sample material' contributing/nonaub tractive tape Is wrapped (ely around the di t non- areas where the plastic caps meet the oue (.all of the brass tube. No preservative other than cold storage is used on Ramples captured in samp containers of this type. lo SAMPLE HANDLING PROCEDURES — —.— Solid--sample _material-is-captured-by advatsc-Ing 6--c-11------ ner into the soil. This ---- -may be done by pushing the liner into soft soils or by containing the liner Sampling Report 88055-C-2 CHEVRON 1918 c Page 9