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●All of the contaminants found in our local water wells are also found in clays. It is <br />impossible to know if any of the listed geologic units present a disposal problem if <br />no element data is provided by the applicant. It is common around the globe for <br />modern mining operations to present this data. I attached examples of typical <br />reports that include the data I am requesting from their mining operation, the files <br />are named: <br />example-of-an-overburden-and-interburden-geochemistry-assessment.pdf <br />example-of-a-groundwater-impact-assessment.pdf <br />The documents can also be found on the internet here: <br />http://www.bhp.com/-/media/bhp/regulatory-information-media/coal/new-south-wa <br />les-energy-coal/mt-arthur-coal/mt-arthur-coal-open-cut-mine-modification-project- <br />exhibition-documents/appendix-i--geochemistry-assessment-of-overburden-and-i <br />nterburden.pdf <br />https://www.bhp.com/-/media/bhp/regulatory-information-media/coal/new-south-w <br />ales-energy-coal/mt-arthur-coal/mt-arthur-coal-open-cut-mine-modification-projec <br />t-exhibition-documents/appendix-b--groundwater-impact-assessment.pdf <br />●This is data that they are surely already in possession of, but which would ideally <br />be collected by a non biased third party using EPA protocols that sample multiple <br />points along a grid for each described geologic member in 6.4.4 Exhibit D. <br />●The sedimentary rocks in that area can have significant iron sulfide. Chemically, <br />the iron sulfide + oxygen in groundwater can result in rust + sulfuric acid. This <br />may explain the dead grass and rusty plumes West of highway 93 and south of <br />the entrance to North Table Mountain Open Space - easily seen from Google <br />Maps or other aerial data sets. <br />2.Assuming the clays harbor some of the elements widely known to cause contamination <br />problems for the local groundwater, the hydrological assumptions they present seem <br />deficient and fail to recognize several features in the hydrologic landscape. <br />●As described in 6.4.4 Exhibit D - Mining Plan - page 12-15, the listed clay units <br />have varied mineralogies that can create differential expansion and contraction <br />rates when (de)hydrated. The differential movements of these laminations can <br />create subsurface fractures to emerge that violate their simplistic hydrologic <br />model. Last year I ran my own experiments on a small patch of one of the <br />described clay units. Via time lapse photos over many months large fracture <br />networks emerged and eventually the slope destabilized and caved. Clays are