ABSTRACT
The stabilisation of Castlehaven area has been planned in an attempt to provide the best outcomes for the human and the natural environment both in the short and long term. The slope stabilisation scheme included the use of 151 deep pump drainage wells, installed with 125 siphon-drains and 35 electro-pneumatic pumps, to reduce winter groundwater levels to the equivalent summer levels where movement is substantially reduced, thus improving landslide stability and at the same time protecting valued environmental assets. This chapter describes the substantial advantages provided by the adopted design approach and by the type of drainage equipment used. A combined coastal protection and landslide stabilisation scheme was planned and designed during the period 2001-2003 to improve the stability of the site. The adopted design approach included the prevention of the sea erosion and landward retreat of the sea cliff and the improvement of the stability of the Upper tier landslide by reducing and stabilising the groundwater level.
