Temporary casings Hui Hon began piling works at the Yuen Chau Kok site in February 1998 using a vibrator that did not have sufficient force to drive the temporary casings down to the founding level required by the contract. On top of this, Hui Hon were coming up against a number of soil problems. Temporary casings were driven down, supposedly to the designated bedrock level Two months later, in an attempt to speed up the work, Hui Hon replaced the vibrator with a Bauer BG 40 drill rig, a machine with greater capacity. However, because suitable parts were lacking, this machine could not be used at full power. Nor was Hui Hon mastering the inherent geological problems. The progress of works was falling further and further behind schedule. The problem was aggravated by the fact that not enough temporary casings were available to permit the construction of several piles at the same time. So, in a totally misguided and unscrupulous attempt to deal with these issues, the directors of Hui Hon decided not to install the temporary casings right down to the proposed founding level. Where the shaft walls lacked temporary casing support, they collapsed and the shaft caved in.