Cost and Data Quality Implications in Current TO-15 Sampling Procedures

摘要

Vapor intrusion (VI) has emerged as a major component of many site investigations. There are many vapor sampling methodologies available including evacuated canister, sorbent tube, passive diffusion, and tedlar bag, however, regulatory preference has made United States Environmental Protection Agency (USEPA) TO-15 the de facto standard. In Method TO-15, evacuated canisters are used to collect the vapor/air samples. TO-15 specifies that vapor flow be controlled by an electronic flow controller or equivalent. Typically, mechanical flow controllers are supplied by the analytical laboratory and used for sample collection. These mechanical flow controllers are subject to failure, that is, a canister that after the designed sampling period has elapsed is at a pressure near the starting pressure, or that have gone to zero (ambient) pressure. These problems can result in additional project costs when samples need to be recollected or the use