In the framework of the expedition of 2018, technogenic formations generated in the late 19th and first half of the 20th centuries on the basis of the Novotroitsk deposit processing tailings were studied. The research methodology included the analysis of satellite observations and field geological and geophysical studies, drilling of geological wells with sampling along the depth of the massif, evaluation of the structure of man-made massif and technological properties of technogenic materials to select the parameters of technologies for its exploitation and processing. The results of the studies showed that arsenic is present in all the samples taken at the depth of the dump. It has been established that the As content with depth increases, which indicates the processes of sulfide oxidation and arsenic migration from the surface layers to the environment. This confirms the expediency of involving the old ore processing tailings into operation with subsequent disposal in specialized storage facilities, including isolated landfills and underground stopes. Based on the results of the research, technological solutions have been proposed for the involvement of tailings into commercial operation with substantiation of the priority order and development direction of mining of the old tailings storage of the Novotroitsk deposit.