Geophysical surveys at the Oitti DNAPL spill site, southern Finland
- Helsinki Univ. of Technology, Espoo (Finland)
- Geological Survey of Finland, Kuopio (Finland)
- New York Univ., NY (United States)
- Ecolution Oy, Helsinki (Finland)
In the 1950`s and 1960`s about 10,000 liters of dry cleaning solvents from a dry cleaning establishment near the town center at Oitti, southern Finland were disposed of in a well and in pits. The groundwater was found to be contaminated in 1992 when a regional groundwater quality survey was done in the region. Among the solvents are trichloroethylene and tetrachloroethylene. Although the major part of the total amount of solvents were deposited in a condensed form into a landfill, the storage sites at the dry cleaning establishment became injection wells by default, because of the permeable nature of the underlying strata (porous sand and gravel, typical of the glacial esker formation overlying the area). The groundwater has been found to be contaminated within a total area of several square kilometres and the amount of polluted groundwater in the esker formation is estimated to be 8 million cubic meters. The main water supply well for the town became contaminated and had to be closed because of high levels of tri- and tetrachloroethylene. Since 1992, the spill site and the whole esker area have been subject to diverse studies aiming at the delineation of the polluted area and at the planning of the remediation methods. In 1995 it was decided to perform geophysical surveys at the site, with two main objectives in mind: first, to delineate the unknown bedrock topography underlying the esker formation, and secondly, to map variations in the groundwater depth in the vicinity of the establishment. The main geophysical methods applied were ground penetrating radar and seismic refraction sounding. Earth resistivity sounding and inductive sounding (EM31) techniques were also applied. On the basis of seismic refraction surveys the depth to bedrock surface could be determined on the flanks of the esker and results from the ground penetrating radar surveys gave information about the groundwater depth and overburden quality variations on and around the spill site.
- OSTI ID:
- 381526
- Report Number(s):
- CONF-960477-; TRN: 96:004278-0060
- Resource Relation:
- Conference: 9. annual symposium on the application of geophysics to engineering and environmental problems, Denver, CO (United States), 15 Apr - 1 May 1996; Other Information: PBD: 1996; Related Information: Is Part Of SAGEEP `96: Proceedings of the symposium on the application of geophysics to engineering and environmental problems; Bell, R.S.; Cramer, M.H. [comps.]; PB: 1353 p.
- Country of Publication:
- United States
- Language:
- English
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