Hazard of petrochemical pollution of ponds of the “Olexandria” arboretum (Bila Tserkva)

Abstract

Groundwater pollution in the territory of Bila Tserkva aircraft repair plant developed in a latent form for decades, in a similar fashion to the territory of any object of the supply of petroleum products. In the early 90s of the last century, the first signs of this pollution were detected in places of natural drainage of the groundwater flow directed to the ponds cascade of the Western Hollow. It should be noted that this cascade of ponds located on the border of the arboretum protects the rest of the park by absorbing pollutants that migrate from the plant territory. More than 10 years of research of the contaminated area with the goal of designing remediation measures began and continued after that. This project was not implemented in full because of a lack of funds. Based on a comparative analysis of the results of ecological and hydrogeological studies of the past years and a modern survey of the western part of the arboretum “Olexandria” and the adjacent territory of the former aircraft repair plant, it was established that pollution of the pond “Poterchata” continues to this day. Over the past 12 years, the scheme of pollutants incoming into ponds has changed. At first, the main stream of oil pollutants directed to the upper reaches of the beam was considered as very dangerous. Nowadays, perhaps due to the remediation measures taken, this flow seems to be exhausted. However, there were signs of discharge of a polluted underground stream in the lower reaches of the pond “Poterchata”. In the soil samples from wells drilled near the water edge, the oil content is 600-900 mg/kg, and in places of water sampling from ponds, the content of dissolved hydrocarbons varies from 2 to 3 mg/dm3, that is, 60 times higher than the standard for fish farms ponds. It is assumed that LNAPL and contaminated groundwater move towards the cascade of ponds of the Western Hollow not in a continuous stream, but in the form of narrow tongues in places of increased conductivity, which are consistent with the lateral shallow gullies crossing the slope of hollow. It is possible that over time, oil pollution will reach the lower “Rusalka” pond. However, one cannot exclude the assumption of natural attenuation processes, the significance of which increased after the closure of the plant and a decrease in the volume of LNAPL because of its extraction from the subsoil. In order to confirm or refute the assumptions made and decide on the need to protect the ponds of the arboretum it has been planned to equip the observation points in places where we should expect influent of pollutants.