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i � <br /> LO GORE-rm SURVEYS ENVIRONMENTAL SITE ASSESSMENT <br /> Io + FOCUSING YOUR REMEDIATION EFFORTS. <br /> 1 Vapor Concentration Calculations <br /> Vapor concentration data from the GORE TM Module, are derived from existing ASTM', MDHS2 and <br /> other accepted and approved methods, developed for passive, sorbent-based, diffusion samplers. <br /> Air: µg/m3 = Mass/System Factor/[(Sampling Rate)(Exposure Time) <br /> C <br /> Soil Gas: µg/m3 =Air/Soil Effectiveness Factor <br /> Mass = GC/MS measured mass from the Module <br /> System Factor= correction factor for the efficiency of adsorption-desorption specific to <br /> the adsorbent, the compound of interest, and the analytical method <br /> CD1 Sampling Rate = liters per hour(L/hr) of contaminated air collected by the Module <br /> C) T Soil Effectiveness Factor(E) =corrects for soil porosity and moisture content <br /> Volume of air determinations were made by measuring the uptake rate of the GORE TM Module over time. <br /> 1 Modules were placed in a sample chamber equipped with a microbalance. Vapor containing toluene <br /> concentrations of 10, 30 and 50 ppm were introduced into the chamber. The mass uptake was recorded <br /> through time, and for each concentration was linear with time. The slopes from each linear concentration <br /> 1 o curve were plotted and modeled. The samolino rate was determined for toluene. In a similar fashion, <br /> O sampling rates were measured for a number of other petroleum and chlorinated compounds. Using these <br /> O <br /> measured sampling rates and physical properties of these compounds, a model was generated to predict <br /> - the sampling rates of similar compounds in our analyte list. <br /> ■r// The masses of the target compounds are derived by desorbing the Module and analyzing the sample <br /> via gas chromatography and mass spectroscopy(GC/MS) following modified EPA methods 8260/8270. <br /> 1 The mass is reported in units of micrograms. <br /> System factors account for the efficiency of adsorption and desorption specific to the adsorbent, the <br /> compound of interest and the GC/MS method. The system factor is calculated for each target compound. <br /> Soil effectiveness factors (E) is applied to the sampling rate to correct for lower potential flow through <br /> 1 the pores of the soil, accounting for physical limitations that can retard the vapor migration process, e.g., <br /> low porosity soils and moisture in the vadose zone pore space. The factor is equal to the ratio of the <br /> effective diffusion of the compounds to the molecular diffusivity of the compound in air. <br /> ' REFERENCES <br /> _ 1. ASTM Methods 6306-98,4597-03,6246-02,and 5314-93 <br /> 2. MDHS Methods,27, 70,and 80 <br /> 3. Millington, R.J.and J.M.Quirk. 1961."Permeability of Porous Solids."Trans. Faraday Sec. 57:1200-1207. <br /> ' 4. User's Guide for the Johnson and Ettinger(1991)Model for Subsurface Vapor Intrusion into Buildings. 2000. <br /> PN050240.004.www.epa.gov/sperfund/prog ram s/risk.airmold/lo hson_ettinger.htm <br /> 00 <br /> 10 <br /> CD <br /> www.gore.com/surveys W.L.Gore&Associates,Inc. Sale Offices: <br /> GORE 100 Chesapeake Blvd. Ewofoa +49-89-4612-2198 <br /> P.O.Box 10 Houston 1-281-405-5540 <br /> lMD 21922-0010 Sari I-415-648-0438 <br /> Tel. 1-410-392-7600 <br /> - <br /> Greaeve Technologies Tel. 1-410.392-7600 <br /> Worldwide Fax.I-410.506-4870 E=iL•environmemalQwlgom.com <br /> The optimal performance of any Gare product is dependent upon how A is incorporated in the final device. Please con tad me of our technical sales associates for <br /> application assistance. <br /> 1 GORE and designs are trademarks of W.L Gore&Associates © Copyright 20D6 W.L.Gore&Associates,Inc. LIT 133.4 <br />