Source Strength Functions from Long-Term Monitoring Data and Spatially Distributed Mass Discharge Measurements

Source strength functions (SSF), defined as contaminant mass discharge or flux-averaged concentration from dense nonaqueous phase liquid (DNAPL) source zones as a function of time, provide a quantitative model of DNAPL source-zone behavior. Such information is useful for making site management decisions. We investigate the use of historic data collected during long-term monitoring (LTM) activities at a site in Rhode Island to predict the SSF based on temporal mass discharge measurements at a fixed location, as well as SSF estimation using mass discharge measurements at a fixed time from three spatially distributed control planes. Mass discharge based on LTM data decreased from ~300 g/day in 1996 to ~70 g/day in 2012 at a control plane downgradient of the suspected DNAPL source zone, and indicates an overall decline of ~80% in 16 years. These measurements were compared to current mass discharge measurements across three spatially distributed control planes. Results indicate that mass discharge increased in the downgradient direction, and was ~6 g/day, ~37 g/day, and ~400 g/day at near, intermediate, and far distances from the suspected source zone, respectively. This behavior was expected given the decreasing trend observed in the LTM data at a fixed location. These two data sets were compared using travel time as a means to plot the data sets on a common axis. The similarity between the two data sets gives greater confidence to the use of this combined data set for site-specific SSF estimation relative to either the sole use of LTM or spatially distributed data sets. This dataset is associated with the following publication: Brooks, M.C., A.L. Wood, J. Cho, C.A.P. Williams, B. Brandon, and M.D. Annable. Source strength functions from long-term monitoring data and spatially distributed mass discharge measurements. JOURNAL OF CONTAMINANT HYDROLOGY. Elsevier Science Ltd, New York, NY, USA, 219: 28-39, (2018).

                                            [
  "020:00"
]
                                        

                                            {
  "fn": "Michael Brooks",
  "hasEmail": "mailto:brooks.michael@epa.gov"
}
                                        

                                            [
  {
    "title": "SDMF-Brooks-20180330.xlsx",
    "mediaType": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
    "downloadURL": "https://pasteur.epa.gov/uploads/10.23719/1432673/SDMF-Brooks-20180330.xlsx"
  }
]
                                        

                                            [
  "long-term monitoring data",
  "mass discharge",
  "mass flux",
  "passive flux meters",
  "source strength function",
  "source zone characterization"
]
                                        

                                            [
  "020:097"
]
                                        

                                            {
  "name": "U.S. EPA Office of Research and Development (ORD)",
  "subOrganizationOf": {
    "name": "U.S. Environmental Protection Agency",
    "subOrganizationOf": {
      "name": "U.S. Government"
    }
  }
}
                                        

                                            [
  "https://doi.org/10.1016/j.jconhyd.2018.09.003"
]
                                        

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