Corrigendum to “The vapor-phase multi-stage CMD test for characterizing contaminant mass discharge associated with VOC sources in the vadose zone: Application to three sites in different lifecycle stages of SVE operations” [J. Contam. Hydrol. 179 (2015) 55–64](S0169772215000674)(10.1016/j.jconhyd.2015.05.006)

We have recognized that there may be potential ambiguity in the presentation of the site conditions and discussion for one of the three sites used for the study reported in Brusseau et al. (2015). With this Erratum, we would like to clarify information presented for the Hassayampa Landfill (HASS) site. Please note that the original conclusions reported in the paper regarding the performance of the contaminant mass discharge (CMD) tests themselves are not affected. The information presented in this Erratum is based on the current Conceptual Site Model (CSM) (Hargis and Associates, 2014). The general stratigraphy for the site consists of, with increasing depth below ground surface, a coarse-grained vadose zone unit (CGZ), a fine-grained vadose zone unit (FGZ), a basalt unit, a sub-basalt vadose zone unit, and Unit A and Unit B groundwater units. Soil vapor extraction (SVE) has been in operation at the site for several years, starting prior to the CMD test. The CMD test conducted for the study reported in Brusseau et al. (2015) was performed in the Special Pits Area. The test used wells screened within the FGZ. Being screened above the basalt unit, these wells are considered to be separated from Unit A groundwater, the surface of which is approximately 3 m below the bottom of the basalt. SVE has been conducted in this area in the past. The CMD test results were used to estimate a CMD value, which was used as input to a nomograph relating magnitude of vapor discharge from a vadose-zone source to theoretical impact on groundwater quality (Fig. 7 of Brusseau et al., 2015). The trichloroethene groundwater concentration estimated from the nomograph was compared to measured groundwater concentrations. The comparison was not meant to imply that there was a direct connection between the wells used for the test from which the data were collected and the sub-basalt Unit A groundwater. We wish to clarify that the wells used for the CMD test are screened above the basalt and are thus considered to be separated from Unit A groundwater, as noted above. Rather, the evaluation was meant to be a conceptual assessment of theoretical contaminant transport behavior. And, we wish to reiterate that this conceptual assessment is subject to the uncertainties discussed in detail in the paper. Finally, we would like to note that vadose-zone VOC sources in areas of the site that lack the basalt unit, and which were not part of our study area, continue to be remediated with SVE. The SVE operation is designed to specifically address soil vapor impact on groundwater quality. We apologize for any potential ambiguity or confusion associated with the original presentation.