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M041 <br /> k�e�� �� ���� <br /> n <br /> b <br /> K <br /> t , <br /> SIERRA <br /> ('. <br /> 6"l SES STANDARD OPERATING PROCEDURE <br /> CA OVM READINGS <br /> SLS uses an orl;anic vapor nieter WVM) to deter-mine lite presence or absence of volatile <br /> 01) organic.compnunds lVC)CsJ,tnchulittgbcnzene,toluene,ethylbcnzcnc,and%ylcncs In sail samples <br /> e.X chosen for field screening. The OVM uses a photnianiz:ttlon detector(I'ID)and is calibrated daily <br /> to 100 parts per trillion of I-litci of isobuty,.ene. -Che ovm.wilicit measures In parts per million <br /> by volume Ippntvl, is Used for ilnalitali%T, rot quantitative, issessinciA because till' correlation <br /> s <br /> between the volume mcasurantettts of the taVb7 and the wcil;ht nteasurentents oC the 1,Aboratory <br /> instnnnellIs is not well definer], <br /> tsfia _ <br /> A field screen sample is obt<rincd from the brays tube lntinedl:ttely above or below the brazs <br /> «� <br /> tube containing the sample selected for possible analysis. Thesoil to be screened is removed from <br /> the brass tube, and is placed in a pre eleaned brass tube with aluminum foil and a po?yethylene <br /> cap on one end. The brass tube is loosely filicd to approximately 1/2 full. Another square of <br /> aluminum foil is placed on the open end and a polyethylene cap with crossed slits is placed over <br /> �y4M <br /> It. <br /> till <br /> amt <br /> ature equilibrate for approxtnlaLely 15 to 30 <br /> The field screen sample is allowed to temper, <br /> ntinul4s in the sun,allowing an,VOCs which might be present in the soil to volatilize out into the <br /> brass tube's heacispace. The OVM nozr.1e is then placed inside the seated brass tube,through the <br /> ]k"11 slits in the cap, in order to measure the VOCs present, if any, in the headspacc. The nozzle <br /> should remain ins.de the brass tube for approximatcly 15 to 30 seconds or until the maximtttn <br /> reading has been recorded on the OVM readout panel. <br /> The depth front which the sample canto and the corresponding OVM reading is recorded <br /> on the original field Jog sheet. Field obscr.~ttions,OVM attd(odor and staining) readings are used <br /> in deLennining which soil samples aye to be analyzed in the laboratory. <br /> OVM.SDI' <br /> Y:Y <br /> i <br /> 1 I <br />