A short evaluation of the monitoring works at the Zlate Moravce site - the former Calex site

The environmental load (EZ) is registered in REZ SAZP under the identifier 'SK/EZ/ZM/1115' and the name 'ZM (013) Zlate Moravce - former Calex site'. It is located in the Nitra region in the town of Zlate Moravce, while the EZ is situated in the inner city, in the industrial zone. It is a EZ with a high priority (K > 65), with a total value of K = 87. The EZ in question is located in the area of the former Calex plant. The most significant source of groundwater pollution is ClU contamination. EZ was created continuously during the operation of the plant, it is not a one-time leak. The main contaminants are tetrachloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE). The estimated area of the contaminated area is 16,000 m². Remediation work on the site took place between 2003 and 2005. The work was focused on pumping and cleaning contaminated water. It was an ex situ physico-chemical remedial hydraulic method. Groundwater was pumped out in order to create a hydraulic depression (barrier) and thereby prevent further spread by groundwater. Subsequent purification took place at the remediation station by physico-chemical or biological processes or a suitable combination thereof. A total of 16,070 m³ of contaminated water was pumped out. During the two-year period, more than 183 kg of ClU were removed. However, a very high concentration of ClU still persists at the site, as only part of the pollution has been removed. Based on the balance method from pollution maps and concentrations measured in 2005, the amount of ClU in the groundwater was approximately determined at 350 kg. Remediation works are currently ongoing and their implementation is planned until the end of 2023. The risk analysis of the site in question confirmed the environmental health risk. Even in the future, these substances will be transported by groundwater, which represents an environmental risk for other components of the environment. However, the real health risk is probably lower than was calculated, as aliphatic hydrocarbons have a high specific gravity and settle at the bottom of the aquifer. Contamination is isolated from the surface by a 4-5 m thick layer of relatively low permeability sediments. In natural aerobic conditions, gradual biodegradation also occurs due to the splitting of the hydrocarbon chain. (authors)