Comparison of techniques for vapor intrusion environmental investigation – Case study: São Paulo – Brazil
Abstract
This article aims to compare the results obtained by two soil vapor sampling techniques for use in the stages of environmental diagnosis in an area contaminated by chlorinated ethynes in groundwater. The two techniques covered in this study are Summa Canister and Continuous Automatic Monitoring. The Summa Canister is a stainless-steel container with negative pres-sure that is coupled through a pipe in the monitoring well. After sample collection, the con-tainer is sent to the laboratory for analysis using the USEPA TO-15 method. Continuous auto-matic monitoring is a technique in which pipes are coupled to the soil vapor monitoring wells and subjected to the application of negative pressure. The sample is sucked from the sam-pling point to the chromatograph injection valve in the mobile laboratory and analyzed by the USEPA TO-14A method. The results obtained using the Summa Canister technique are ex-pressed as point-in-time measurements, that is, a single concentration per sampling point representing a specific time period. The continuous automatic monitoring technique brings concentration results in real time throughout the sampling period. It is concluded that the results provided by continuous automatic monitoring allow a more assertive diagnosis of the processes of vapor intrusion in the study area. The trend analysis of the results combined with possible external interference such as environmental variables allows more appropriate con-tamination management, facilitating decision making.
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