Groundwater Monitoring and Isotope Investigation of Contaminated Wastewater from an Open Pit Mining Lake

Abstract

In an open pit mining lake in the Central‐German lignite district, untreated pyrolysis water from lignite smouldery was disposed of for> 15 years. The water is highly contaminated with phenols, ammonium, and polyaromatic hydrocarbon, resulting in an extremely high dissolved organic carbon content. Several aquifers are in danger of being polluted by leaking wastewater. Since 1993, the water in up to 24 wells around the lake in different Quaternary and Tertiary aquifers was monitored two to six times per year for organic and inorganic pollutants. Isotope data (deuterium, oxygen, tritium, nitrogen) and hydrochemical investigations were used to assess the influence of lake water on groundwater. Data gathered to date shows <5% of contaminated lake water in the downstream groundwater. Nevertheless, this leakage water has a sustainable influence on the groundwater quality at least locally. Furthermore, isotope data suggest lower flow velocities within the underlying aquifer than was expected.

Environmental Pollution by Wastewater From Brown Coal Processing ¬ a Remediation Case Study in Germany

“…However, the insufficiently treated (Table 3) and, in occasional cases, even untreated wastewater was released into the environment such as rivers, lakes, unused fallow land, and former open-cast mines for disposal or seepage (Stottmeister et al 1999;Eccarius et al 2001). In some cases, the wastewater was pumped into the deep layers of the Upper Permian Zechstein (Eccarius 1998). The long-term input of the wastewater into abandoned open-cast mines resulted in the formation of large ponds with a significant potential environmental danger particularly for groundwater and the human population of the surrounding areas (Eccarius 1998).…”

“…In some cases, the wastewater was pumped into the deep layers of the Upper Permian Zechstein (Eccarius 1998). The long-term input of the wastewater into abandoned open-cast mines resulted in the formation of large ponds with a significant potential environmental danger particularly for groundwater and the human population of the surrounding areas (Eccarius 1998).…”

Gas Pressure Dynamics in Small and Mid-Size Lakes

“…The pit was (until 1969) used to dispose of wastewater from lignite processing. There is no surficial inflow or outflow but exchange with groundwater balancing the evaporation deficit and causing groundwater contamination in the near vicinity of the lake [50,51]. Hence it is heavily affected through its history as a dumping site.…”