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KA.JESTIC TECH <br /> 2 MONITORING <br /> 10. 2. 1 FLAMMABLE/EXPLOSIVE ATMOSPHERES: <br /> A combustible gas indicator (CGI ) shall be used to detect <br /> and evaulate flammable/exlosive ( 10% LEL) and oxygen <br /> deficient (<19. 5% 0: ) atmospheres. This monitoring shall <br /> be conducted for the following project tasks: <br /> When inerting tanks and pipelines prior to remove_ <br /> When inerting tamnks prior to performing hot work <br /> In the event of a chemical spill <br /> Any other time work operations or conditions may result <br /> in the generation of a flammable/explosive and/or <br /> oxygen deficient atmosphere <br /> When evaluating tank atmospheres, representative samples <br /> shall be taken from different locations/levels within a tank <br /> 10. 2. 2 HYDROCARBON VAPORS <br /> An Organic Vapor Analyter (OVA) shall be used to detect and <br /> evaluate low airborne concentrations of hydrocarbon vapors . <br /> The volitile organic hydrearbons identified in this project <br /> have ioni>-ation potentials ranging from 8. 44 eV (Xylene) to <br /> 11 . 0 eV (Trichloroethane) , and will generally be detectable <br /> using an OVA instrument. Atmospheric measurements will be <br /> used to detect the presence Of airborne contamination <br /> following tank/pipeline removal. <br /> All airborne measuremnts shall be Compared to background <br /> readings and not "meter Zero" readings. Background readings <br /> shall be obtained prior to the beginning of each day ' s <br /> operations, and shall be updated at least twice (or more <br /> frequently if surrounding conditins are chaninging) . <br /> Background readings are intended to take into account <br /> hydrocarbon sources which are independent of project sourceE <br /> (i. e. tank residues and contaimated soils ) , including <br /> on-site equipment exhaust, aircraaft activity, and adjacent <br /> vehicle traffic. Therefore, rsedints ABOVE BACKGROUND shall <br /> be evaluated to determine proper safety actions (see below) . <br /> Background measurements shall be taken at breathing zone <br /> height upwind of the work area. In addition, downwind <br /> measurements shall be taken with backhoe and/or other <br /> equipment units Operating, but before actual work begins , in <br /> Order to determine the influence of equipment exhaust on <br /> background readings. These readings shall be addded to the <br /> upwind measurements when determining daily background <br /> levels . <br />