A case study was carried out at an old landfill site (Riet site) located in Winterthur, northern Switzerland. The Riet site contains mainly municipal solid wastes (MSW) comprising four discrete unlined landfill compartments, the oldest of which dates back to 1918. One goal of the case study was to assess the investigative techniques used to determine the risk of groundwater contamination. Waste compartments and leachate plumes were delineated with the electromagnetic method EM31 and with tracer methods. The most efficient methods for a risk assessment were flow modelling based on reliable hydraulic head and hydraulic conductivity measurements, and chemical analyses. Chemical analyses of leachate and groundwater samples showed that the older compartments of the landfill pose only a small risk to the groundwater. The other goal of the study was to determine the long-term risk of groundwater contamination posed by MSW landfills of different ages. To this end, chemical concentrations of leachate from the Riet site were compared with those of other MSW landfills of various ages. The long-term risk of landfill compartments older than about 1960 can be considered in general to be considerably smaller than that of younger ones. Age of the compartment and leachate concentrations could be correlated.
Abbaspour, K., Matta, V., Huggenberger, P. & Johnson, C.A. (1999) A contaminated site investigation: Comparison of information gained from geophysical measurements and hydrogeological modeling . Journal of Contaminant Hydrology40, 365-380.
2.
Abbaspour, K.C., Schulin, R., van Genuchten, M. Th. & Schläppi, E.(1998) Procedures for uncertainty analyses applied to a landfill leachate plume. Ground Water36, 874-883.
3.
Abbaspour, K.C., van Genuchten, M. Th., Schulin, R. & Schläppi, E. (1997) A sequential uncertainty domain inverse procedure for estimating subsurface flow and transport parameters. Water Resources Research33, 1879-1892.
4.
Amirbahman, A., Schoenenberger, R., Johnson, C.A. & Sigg, L. (1998) Aqueous- and solid-phase biogeochemistry of a calcareous aquifer system downgradient from a municipal solid waste landfill (Winterthur, Switzerland). Environmental Science & Technology32, 1933-1940.
5.
Baccini, P., Henseler, G., Figi, R. & Belevi, H. (1987) Water and element balances in municipal solid waste landfills. Waste Management & Research5, 483-499.
6.
Barth, S., Hemming, N.G., Hanson, G.N., Hoehn, E. & Gercken, B. (1996). Proceedings of the 6th V. M. Goldschmidt Conference, I, Cambridge, UK: Cambridge Publications , p. 46.
7.
Bassett, R.L., Buszka, P.M., Davidson, G.R. & Chong-Diaz, D. (1995) Identification of groundwater solute sources using boron isotopic composition. Environmental Science & Technology29, 2915-2922.
8.
Beaven, R.P. & Walker, A.N. (1997) Evaluation of the total pollution load of MSW. Proceedings of Sardinia 97I, 6th International Landfill Symposium , Cagliari, Italy: Environmental Sanitary Engineering Centre, pp. 57-71.
9.
Belevi, H. & Baccini, P. (1989) Long-term behaviour of municipal solid waste landfills . Waste Management & Research7, 43-56.
10.
Bjerg, P.L., Rügge, K., Pedersen, J.K. & Christensen, Th. H. (1995) Distribution of redox-sensitive groundwaer quality parameters downgradient of a landfill (Grindsted, Denmark) . Environmental Science & Technology29, 1387-1394.
11.
Buwal (1998) Verordnung über die Sanierung von belasteten Standorten (Federal Ordinance on the Clean-Up of Contaminated Sites), Swiss Federal Office of the Environment, Forest and Landscape, 26 August 1998, SR 814.680.
12.
Cherry, J.A., Gillham, R.W., Andersen, E.G. & Johnson, P.E. (1983) Migration of contaminants in groundwater at a landfill: a case study, 2. Groundwater monitoring devices. Journal of Hydrology63, 1-29.
13.
Christensen, T.H., Kjeldsen, P., Albrechtsen, H.-J., Heron, G., Nielsen, P.H., Bjerg, P.L. & Holm, P.E. (1994) Attenuation of landfill leachate pollutants in aquifers. Critical Reviews in Environmental Science24, 119-202.
14.
Drost, W. (1986) Groundwater measurements by means of radioactive tracers. Atomenergie/Kerntechnik48, 81-86.
15.
Farquhar, C.J. & Rovers, F.A. (1973) Gas production during refuse decomposition. Water Air & Soil Pollution2, 483-495.
16.
Freeze, R.A., James, B., Massmann, J., Sperling, T. & Smith, L. (1992) Hydrogeological decision analysis: 4. The concept of data worth and its use in the development of site investigation strategies . Ground Water30, 754-588.
17.
Freeze, R.A., Massmann, J., Smith, L., Sperling, T. & James, B. (1990) Hydrogeological decision analysis: 1. A framework . Ground Water28, 738-766.
18.
Greenhouse, J.P. & Slaine, D.D. (1983) The use of reconnaissance electromagnetic methods to map contaminant migration. Ground Water Monitoring Review3, 47-59.
19.
Hemming, N.G. & Hanson, G.N. (1994) A procedure for the isotopic analysis of boron by negative thermal ionization mass spectrometry. Chemical Geology (Isotope Geoscience Section)114, 147-156.
20.
Heyer, K.-U., Packert, A. & Stegmann, R. (1996) Untersuchungen zum langfristigen Emissionsverhalten von Abfällen im Deponiekörper (Investigations on the long-term emissions of wastes in landfills). Müll & Abfall4, 230-241.
21.
Hoehn, E. (1999) Preliminary analysis of boron isotope ratios in leachate contaminated groundwater. In: Integrated Methods in Catchment Hydrology, Proceedings of IUGG 99 Symposium HS4. IAHS Publication No. 258, pp. 193-197.
22.
Hoehn, E. & Honold, P. (1999) Schonende Entnahme von Materialproben aus Bohrungen in grobkörnigen grundwasserführenden Lockergesteinen ohne Luftkontakt (Sampling non-cohesive aquifer materials in ground water from bore cores, taken air-tight and with little physical disturbance). Grundwasser4, 119-124.
23.
Hofer, M., Aeschbach-Hertig, W., Beyerle, U., Haderlein, S.B., Hoehn, E., Hofstetter, T. h. B., Johnson, C.A. , Kipfer, R., Ulrich , A. & Imboden, D.M. (1997) Tracers as essential tools in the investigation of physical and chemical processes in groundwater systems. Chimia51, 941-946.
24.
Johnson, C.A. & Hoehn, E. (1998) The influence of old municipal solid waste landfills on groundwater quality. EAWAG-News44E, 12-17.
25.
Johnson, C.A., Moench, H. & Brandenberger, S. (1999) The characterization and long-term behaviour of the fine fraction of sorted demolition wastes. Journal of Environmental Quality28, 1061-1067.
26.
Kinzelbach, W. & Rausch, R. (1995) Grundwassermodellierungen - Eine Einführung mit Uebungen (Groundwater Modelling - An introduction with exercises). Berlin: Gebrüder Bomtaeger.
27.
Lyngkilde, J. & Christensen, Th. H. (1992) Fate of organic contaminants in the redox zones of a landfill leachate pollution plume (Vejen, Denmark) . Journal of Contaminant Hydrology10, 291-307.
28.
MacDonald, J.A. & Kavanaugh, M.C. (1994) Restoring contaminated groundwater: an achivable goal? Environmental Science & Technology28, 362-368.
29.
Martinson, C. (1994) Geochemical interactions of a saline leachate with Molasse at a landfill site: a case study. Eclogae geologicae Helvetiae87, 473-486.
30.
Massmann, J., Freeze, R.A., Smith, L., Sperling, T. & James, B. (1991) Hydrogeological decision analysis: 2. Applications to ground water contamination. Ground Water29, 536-548.
31.
Robinson, H.D. & Gronow, J. (1995) Tritium levels in leachate from domestic wastes in landfill sites. Proceedings of Sardinia 95I, 5th International Landfill Symposium, Cagliari, Italy: Environmental Sanitary Engineering Centre, pp. 377-390.
32.
Robinson, H.D. & Lucas, J.L. (1985) Leachate attenuation in the unsaturated zone beneath landfills: instrumentation and monitoring of a site in southern England. Water Science Technology17, 477-492.
33.
Studiengruppe Verdunstung (1978) Die Verdunstung in der Schweiz (Evaporation in Switzerland). Beitr. Geol. Schweiz - Hydrol., Vol. 25.
34.
Zweifel, H.R., Johnson, C.A. & Hoehn, E. (1999) Langzeitanalysen der Hauptelemente von Sickerwässern aus Altdeponien (Long-term analyses of the main leachate constituents from old waste disposal sites). Müll & Abfall31, 727-732.
