Underground Pollution at a Former Military Installation in Valciunai (Lithuania)

Abstract

For 30 years, light oil products and rocket fuels were stored at this former military fuel depot. Light and dense non-aqueous phase liquids have polluted natural environment beneath the territory of Valciunai Oil Product base. Pollutants occur in groundwater both as a dissolved aqueous plume and as pure product. In the polluted areas hazardous compounds migrate both laterally and vertically (downward). The main ecological problems are: firstly, the polluted area situated in the watershed of two rivers and shallow groundwater flowing from the base’s territory drains into the one of these. Secondly, it is within the third protection zone of the groundwater reservoir supplying water to Vilnius; chemical pollution in this zone is prohibited. The investigations of polluted underground in this site are carrying out more than 3 years. A monitoring network for regular observation of the evolution of the extent of underground pollution has been created. Oil products have accumulated on the shallow groundwater table below the central part of the base. Free phase oil covers an area of 3,000 – 3,500 m², with a maximum thickness of c. 2 m. Local accumulation of oil product has been controlled by the lithology and structure of aquifer sediments. The size of the polluted area is thus increasing. In order to hinder the migration of oil products, remediation of the subsurface has started. In the initial five months of a pump-treat-recirculate system, more than 150 m³ of liquid oil products have been extracted.