Author:
Lauge Clausen | Technical University of Denmark | Denmark
Regeneration of brownfield mega-sites – a review of existing and emerging technologies and their application for a test-site
By
Lauge PW Clausen1*, Stephan Bartke2, Mariusz Kalisz3, Janusz Krupanek3, Nicolas Fatin-Rouge4, Mette Algreen1 and Stefan Trapp1
1 Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
2 Helmholtz Centre for Environmental Research – UFZ, Permoserstr. 15, 04318 Leipzig, Germany
3 Institute for Ecology of Industrial Areas, 6 Kossutha Street, Katowice, Poland
4 Institute UTINAM (UMR CNRS 6213), University of Franche-Comté, 25030 Besançon cedex, France
* Corresponding Author: Tel +45 4525 1477; e-mail: lpwc@env.dtu.dk
Keywords: Brownfield, mega-site, regeneration, remediation, phytoremediation, monitored natural attenuation, In-situ chemical oxidation, soil-flushing and composting.
Abstract
Background: This study aims to answer the question of which technologies that can overcome the remediation challenge of brownfield mega-sites. We reviewed potential remediation strategies and assessed their applicability for a former Soviet military air-base at Szprotawa, Poland, with a BTEX contaminated area of roughly 75 ha. The remediation technologies reviewed are: monitored natural attenuation MNA, phytoremediation or phyto-enhanced natural attenuation, in-situ chemical oxidation (ISCO), soil-flushing and ex-situ composting. The assessment is done based on data acquired by site screening with direct-push, soil gas measurements, phytoscreening and soil and groundwater monitoring.
Results and discussion: Results from the screening allowed us to make a pre-selection of methods. Soil gas measurements on methane (high), oxygen (low) and CO2 (high) prove ongoing natural attenuation processes. The high permeability of the soil allows air sparging, bioventing or soil-flushing of the source zone. Presence of BTEX in tree cores shows that tree roots reach the subsurface plume. By uptake of pollutants, rhizo-and phytodegradation, natural attenuation would be enhanced. Most importantly, trees transpire water which increase aerated soil pore space and lower groundwater level – drawing down oxygen. Direct-push did not only give a 3-D picture of the NAPL, but yielded also information on the hydrological conditions and aquifer material. The hot spot areas (approx. 100 000 m3) has levels above 10 g/kg hydrocarbons, mostly kerosene, and cannot be treated by MNA or phytoremediation within reasonable time. Here, in-situ treatments like ISCO or air sparging would be applicable. Conclusion: The use of pre-screening methods, such as soil gas measurements, tree coring and direct-push, does not only lead to a denser grid and better survey of contaminated sites. The information collected can also be used to judge and pre-select remediation methods, as was shown for the former Soviet military airport Szprotawa. In this case, ISCO, soil-flushing and air sparging for the centre of the plume, combined with phytoremediation and MNA, would be suitable and cost-efficient. At construction sites, where soil is excavated anyway, on-site composting or dumping are rapid alternatives.