Analysis of partitioning interwell tracer tests

Partitioning interwell tracer tests (PITTs) have emerged as a useful tool in characterizing the Volume of nonaqueous phase liquids (NAPLs) in contaminated aquifers. More than 40 PITTs have been conducted in various NAPL-contaminated sites far both initial estimation of NAPL volume and postremediation performance assessment of various cleanup technologies. An effective interpretation of PITT results requires an accurate determination of the confidence limits of the volume of NAPL estimated from PITT data. This necessitates a description of the various errors, both systematic and random, associated with the measurement and analysis of PITT data. In this paper, an approach for performing this error analysis for both vadose-zone and saturated-zone PITTs is presented. This approach is based upon identifying the various sources of errors in both the measurement of PITT data and the errors from the data analysis using the method of temporal moments. Results are illustrated using our data from several soil column studies and two field PITTs, one saturated and one unsaturated.