ESTIMATION OF HYDRAULIC CONDUCTIVITY OF ARTIFICIAL FINEGRAINED SOIL BASED ON PORCHET METHOD – EXAMPLE OF TAILINGS POND “GILÓW”, SW POLAND.

The paper presents the results of the field experiment conducted at the closed tailings facility “Gilów”, which is located in Legnica-Głogów Copper District (SW Poland). The tailings pond had been operated between 1968 and 1980 as the primary place of waste disposal from copper processing plants of Polish copper mining industry. The dams of the pond had been built up with tailings which are impregnated with salt (NaCl) coming from underground brines. The aim of the study was to investigate the actual permeability of the material disposed in the pond and in its dams for future modeling of pollution migration. The method chosen for the experiment was Porchet method (inversed auger hole) with automated measurements of the observed water levels, temperature and the pressure. The study had been conducted at 3 tests sites situated in different parts of the pond. Hydraulic conductivity had been estimated in 47 boreholes in total. Results show that permeability of the fine grained artificial soil of “Gilów” pond can be classified as very slow (k = 3.56*10-7 m/s) to very rapid (k= 6.25*10-3 m/s). It mainly depends on the granulation of the soil (fine sand, clayey sand, silty sand and silt). The study confirmed that application of the Porchet method supported by automatic measurements is fast, relatively inexpensive and accurate enough to be a reliable source of input data for hydrogeological modeling. [ABSTRACT FROM AUTHOR]