A Comparison of EPA Methods 8260B and TO-14A/15 forthe analysis of VOCs in Soil Gas: Application to UpwardVapor Intrusion Risk Studies

摘要

The determination of Volatile Organic Compounds (VOCs) in soil vapor (gas) isnecessary in order to obtain empirical data to enter into risk models for upward vaporintrusion. Several EPA Methods are currently being used to furnish the regulatorycommunity with this information. Two of the most commonly used are EPA Method8260B (from SW-846) and the two similar ambient air methods EPA TO-14A and TO-15. None of the methods were originally designed to apply to soil vapor and as such allare being modified by analytical chemists and laboratories in order to make themamenable to the soil vapor matrix.A comparison of the methods will be presented that shows the similarities and thedifferences between the two procedures. The protocols for sampling of soil vapor, theanalytical instrumentation used, standardization and calibration procedures, range anddetection limits will be contrasted along with those modifications necessary to apply thewritten methods to soil gas. The advantages of each of the three methods along with theassumptions and weaknesses inherent in each method will be presented with the objectiveof utilizing all three in a complementary fashion. Finally, parallel analysis of soil vaporsamples by EPA 8260B and TO-15 performed in the author' s laboratories will bepresented to support the theoretical conclusions.