A comprehensive study of in situ retorting at the Logan Wash has indicated the importance of developing baseline information including raw shale characterization, the elucidation of mineralogical and chemical controls on trace element mobilities from shales subjected to in situ processing, and the research necessary to identify strategies for control of recognized environmental impacts. It is impossible to assess the magnitude of trace element releases to be expected from a commercial in situ facility once banks of retorts or the entire facility is abandoned and dewatering of the area is concluded. However, laboratory-scale studies can indeed identify the relative environmental acceptability of spent shale materials generated by in situ processing. In this research, an attempt was made to relate mineralogy and leaching behavior of field-generated materials with leachate composition and solution chemical processes. The interaction of these factors will ultimately affect the impact of in situ processing on surface and groundwater quality.