Determination of the petroleum pollution sources for groundwater (on the example of Solotvino territory in the Precarpathians)

The article is dedicated to solution of groundwater oil products pollution problem within area of Solotvyn village, which is located in Precarpathians, Ivano-Frankivsk region of Ukraine. Contamination was found in the wells of drinking water supply with specific taste and smell. The alternative sources of pollution are considered: conserved oil well, oil pipeline and gas station (GS). All owners of these facilities submitted survey or test documents confirming tightness (well and gas station tanks) or lack of hydrocarbons (inactive pipeline). A paradoxical situation arose: there is pollution, but there are no sources of pollution. To solve the problem, the complex of geochemical and geophysical methods was applied. Geochemical studies were conducted for water samples taken from wells in the contaminated area and adjacent areas. In addition, samples of near-surface air in the soil were collected on the condensed network. The level of heavy and light hydrocarbons in polluted water samples exceeded the background values by tens of times and exceeded the permissible concentrations. Laboratory tests of air samples clarified and detailed the contaminated area. According to the results of geochemical surveys it was found that the source of pollution can be located on the GS territory. Geophysical studies have allowed finding out the lithological structure of the upper part of the section and establishing the depth of the roof and the bottom of the groundwater collector and, accordingly, the underlying aquifer roof. At the same time, the filtration direction in aquifer and a location of old river channel that are in correlation with spreading of groundwater from GS to polluted wells. The report on the causes of groundwater pollution with oil products and on the established source of pollution was submitted to the relevant authorities of the State Service of Ukraine for Emergency Situations.