PHREEQC program used to calculate mineral-saturation indices from groundwater quality data collected at a confined disposal facility in East Chicago, Indiana

The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers (USACE), conducted a study from June 2014 through November 2014 to identify the hydrologic, chemical and microbiologic processes affecting declining pump performance and frequent pump failure at a confined disposal facility (CDF) in East Chicago, Indiana. A decline in groundwater pump performance through time is not uncommon and is generally attributed to biofouling. To better understand the causes behind declining pump performance, data were collected to describe the geochemistry and microbiology of groundwater and solids collected from extraction and monitoring wells at the CDF. Mineral-saturation indices were computed using PHREEQC software (Parkhurst and Appelo, 2013) for groundwater samples collected from extraction wells ( EW-4B, EW-22B, and EW-14A) and monitoring wells (MW-4A, MW-11A, and MW14A) during four sampling regimes between September 9th and November 6th, 2014. In addition, mineral-saturation indices were computed for multiple hypothetical mixtures of groundwater from EW-4B, collected on October 9, 2014, and groundwater from D40, collected on June 14, 1993, to explore the effects that over-pumping and inducing shallow, oxygenated water into the well screen have on mineral precipitation. Source code and all input/output files associated with the PHREEQC program were archived in compressed folders and are disseminated with this USGS Data Release. Documentation on the files is provided under each subdirectory in the model archive.

[
  "010:12"
]

[
  "geospatial"
]