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Section 1: Investigation, hazard assessment and remediation of existing landfills |
1 School of Civil Engineering, Kingston University, Penrhyn Rd, Kingston upon Thames, Surrey KT1 2EE, UK
2 Dipartimento di Scienze della Terra, Università degli Studi di Siena, Sienna, Italy
3 Geography Laboratory, University of Sussex, Falmer, Brighton, Sussex BN1 9QN, UK
The paper describes the stabilization of a solid urban waste dump near Ancona, Marche Region, Italy. The 40 000 m2 dump was established on the western slope of Monte Umbriano on a slope of 8°–10° over underlying materials comprising sandy-silty colluvial clays. Refuse was deposited to a maximum height of 13 m with a graded slope. Prior to placing the refuse, trench drains were constructed parallel to the direction of maximum slope. These drains were filled with 18–21 mm washed river gravel protected by geotextiles. The leachate from the tip was collected from the drains, and led to drainage shafts connected to a treatment plant.
In August 1988, active slip surfaces were encountered in the inspection shaft at a depth of about 9 m below ground surface. Following the installation of inclinometers, the slow mass movement of the whole of the slope was confirmed. The causes of the slip were studied via a series of field and laboratory investigations, and a series of stability analyses were undertaken.
The slope was stabilized by the construction of a system of deep drainage. The area of the existing tip was drained by installing subhorizontal drilled drains from pits near the toe of the waste dump, and the area of extension of the tip was drained by deep shafts from which an array of bored drains were installed. The extension of the tip over the drained area appears to have been successfully completed. Leachate from the tip has been collected and fed to the existing purification works for treatment.
