INTRODUCTION
Hong Kong's long-term waste disposal strategy is based on the use of three very large regional landfills outside the urban area. Waste will be taken to these landfills in a containerised form from refuse transfer stations (RTS) built close to major centres of population. An initial appraisal of a site at Mt. Davis for an underground RTS was made in 1988 as part of the SPUN (Potential Use of Underground Space) Study undertaken by the Geotechnical Engineering Office (GEO) (formerly Geotechnical Control Office). The study confirmed that this cavern development was a viable alternative to conventional development above ground, and one which could confer significant environmental benefits. Following the SPUN Study, the GEO engaged a consultant to undertake further study on the project (GCO, 1991). One of the principal objectives was to carry out site investigations to confirm the suitability of the ground conditions for cavern construction.
THE SITE
The proposed site is situated on the west side of Mt Davis, which is characterised by thickly vegetated hill slopes falling towards the sea (Figure 1). Below Victoria Road, the hillside dips steeply at an angle up to 45° . The main rock type within the proposed cavern site is tuff. A sequence of eutauxite belonging to the same formation and lenses of sandstone up to 25 metres in thickness are present. In the area, the major faulting is in NE-SW.
