Objective The project is to clean up the soil of the Nettelbeck railway station that is contaminated by hydrocarbons due to approximately 30 years of trans-shipment activities. Soil excavation not being possible without seriously disturbing normal operation at the station, OHE decided to wash the soil using the FRAK technology for breaking up the bound soil structures. The soil is then percolated in situ with water enriched with nutrients and oxygen in order to create optimum conditions for microbial activity; the groundwater whose level is closely below the surface is extracted and hydrocarbons are skimmed off by an external skim reactor.Successful clean up was demonstrated of soil contaminated by mineral oil at an average concentration of 3.500 mg hydrocarbons per kg. The goal was to clean up the soil to concentration values below 1.000 mg/kg and groundwater to concentrations of less than 0.1 mg/l, the national tolerability limits being 0.4 mg/l. It was shown that this in situ clean up had no adverse effects on the neighbouring groundwater environment.The process was to extract polluted groundwater, remove oil beyond the dilution limits of approximately 5 mg/l, load the cleaned water with oxygen and nutrients and percolate the soil with the recycled water. Within this cycle, microbes feeding on mineral oil digested the remaining hydrocarbons. it could be shown that the initial nutrient reservoir was used up during digestion, which made the addition of phosphate and nitrate necessary in later phases of the cycle. To achieve clean up to the goals set, the percolating water (about 75 times the average rainfall quantity) had to be recycled approximately 160 times.The rate of hydrocarbon removal was remarkable: within 8 weeks on the average, approximately 90% of the contaminants could be removed. The digestion and percolation processes were greatly enhanced by air pressure assisted tear up of the soil structure using a FRAK installation. Water percolation was drastically enhanced by a factor of 5, which made the microbial in situ treatment of soils with low penetrability value below 1E-4 feasible.The feasibility and potential of microbially cleaning up halocarbon pollution in situ even if the contaminated soil is difficult or even impossible to access due to low penetrability, by applying the FRAK process to tear up the soil structure and make the soil accessible to percolation, was demonstrated. Further, free mineral oil was released into the groundwater wells, which is highly desirable, as this will remove latent oil pollution hazards from free oil and oil collected in oil lenses.After two years of operation, German authorities accepted the FRAK-assisted microbial clean-up of the railway trans-shipment site of OSTHANNOVERSCHE EISENBAHNEN AG (OHE) at Nettelbeck near Hamburg which had been contaminated with mineral oil as satisfactory. This demonstration of the efficiency of the FRAK installation was granted assistance by the European Commission, within its ACE 89 programme on demonstration projects on clean technologies and contaminated site monitoring and rehabilitation. The project demonstrated the successful clean-up of soil contaminated by mineral oil at an average concentration of 3.500 mg hydrocarbons per kg. The goal was to clean up the soil to concentration values below 1.000 mg/kg and groundwater to concentrations of less than 0,1 mg/l, the national tolerability limits being 0,4 mg/l. It was shown that this in-situ clean-up had no adverse effects on the neighbouring groundwater environment. The process was to extract polluted groundwater, remove oil beyond the dilution limits of approximately 5 mg/l, load the cleaned-up water with oxygen and nutrients and percolate the soil with the recycled water. Within this cycle, microbes feeding on mineral oil digested the remaining hydrocarbons. It could be shown that the initial nutrient reservoir was used up during digestion, which made the addition of phosphate and nitrate necessary in later phases of the cycle. To achieve clean-up to the goals set, the percolating water - ca. 75 times the average rainfall quantity - had to be recycled for approximately 160 times. The rate of hydrocarbon removal was remarkable: within eight weeks on the average, approximately 90% of the contaminants could be removed. The digestion and percolation processes were greatly enhanced by air-pressure-assisted tear-up of the soil structure using a FRAK installation that had been constructed by DETLEF HEGEMANN ENGINEERING GmbH with Commission assistance within the ACE 89 programme; water percolation was drastically enhanced by a factor of five, which made the microbial in-situ treatment of soils with low penetrability (kF) value below 10-4 feasible. Thus, this project demonstrated the feasibility and potential of microbially cleaning up halocarbon pollution in situ even if the contaminated soil is difficult or even impossible to access due to low penetrability, by applying the FRAK process to tear up the soil structure and make the soil accessible to percolation. Programme(s) ENV-ACE 2 - Action (EEC) by the Community relating to the environment (ACE), 1987-1991 Topic(s) Data not available Call for proposal Data not available Funding Scheme DEM - Demonstration contracts Coordinator Osthannoversche Eisenbahnen AG EU contribution No data Address Biermannstraße 33 29221 Celle Germany See on map Total cost No data
