The use of Super Mud to support the walls of the excavated pile shafts had not been approved by HD. Witnesses revealed that Hui Hon had stored many tubs of Super Mud on site in a large shipping container. Some were even placed quite blatantly right outside HD’s site office.
Two HD works supervisors took note of these tubs, and when one of them asked Hui Hon staff about it, he was told that the materials were used for excavation. The second works supervisor also learnt from another Hui Hon staff member that the materials had been used for quite a while, and no further questions were asked.
Where Super Mud was used in the pile shafts, the water flowing from the shafts appeared unusually milky. The project assistant clerk of works of HD once questioned why this should be so, but Hui Hon staff were quick to reply that it was due to the lubricant being used in the boring machine.
Hui Hon managed to avoid anybody discovering the use of Super Mud throughout.
An assistant engineer who worked at the Yuen Chau Kok site from 14 May to July 1998, and who was responsible for supervising construction workers and for compiling progress reports, told the ICAC that when he became aware that certain procedures were irregular, he wanted very much to resign. He was later transferred to another site, however, and remained employed by Hui Hon.
In fact, he admitted to having had no prior experience in the construction of large diameter bored piles. It was only through reading the works manual that he understood such piles had to rest on bedrock and that the temporary casings should be driven down right to the bottom of the of pile shafts. As the excavation works progressed, he realized that the temporary casings did not reach the base of the shafts. He said however that his superior (the site agent) instructed him to falsify the lengths of the temporary casings. He confirmed that all these reported lengths were false.
The assistant engineer went on to say that since the collapsed soil in the pile shafts had reduced the actual length of the pile, less concrete would be consumed. The ex-directors of Hui Hon asked him to use the surplus concrete for road paving. When he filled in the concrete records, he asked the site agent how to report the quantity of concrete used and was told to “shape the facts to fit the situation”. He therefore falsified these records as well. The site agent explained that when he sought advice from the two ex-directors of Hui Hon on the same issue, they had similarly instructed him to falsify records.
After the assistant engineer was posted to another construction site, the vacancy was filled by an engineer who had just graduated. He stated that the two ex-directors of Hui Hon and the site agent had told him to have workers shorten the measuring tape that would be used to measure the actual length of the pile. This became known as the “magic measuring tape”.
One piling worker revealed that this young assistant engineer had asked him to drill the pile to at least 40 m when taking core samples. When the worker reported that the drilling had been impeded by blockages within the pile, the assistant engineer instructed him to tidy up the drill hole and shorten the tape before HD staff measured the length of the pile.
The worker said that he could not recollect who actually cut the tape. He did state however that he accompanied the assistant engineer when the HD staff inspected the pile length and that he was the one to lower the tape. At that time, he saw the HD staff read the measurement off the tape and then sign to confirm the total length of the pile.
As part of the quality assurance plan, the contract called for major work procedures to be supervised by HD staff. On the pretext of having to meet deadlines, Hui Hon regularly arranged for major work to be carried out after 7:00 pm, when the HD supervising staff had left. HD issued as many as 29 warning memos to Hui Hon demanding that they rectify this situation, but Hui Hon ignored these and continued with major work at night.
One procedure which was deliberately conducted at night by Hui Hon to cover up a major problem was the construction of the bell-out. This had been rendered difficult, if not impossible, because of the soil collapses in most of the pile shafts. Hui Hon’s ruse was to install permanent linings at night before the HD staff could inspect the bell-out, thus effectively depriving HD of the opportunity to verify that it had been successfully constructed.
Hui Hon also took to installing reinforcement cages at night. The contract called for HD staff to measure the length of each reinforcement cage before installation to ensure that the length matched the depth of the pile shaft as reported. Where the pile shaft had not reached founding level, part of the reinforcement cage would be left sticking up above ground, and this had to be removed. If the reinforcement cages could be installed at night the entire process would escape HD monitoring. According to a witness, the excess steel removed was either used in pile capping or simply thrown into the shafts.
Hui Hon further arranged for most of the concreting work to be completed well after 7:00 pm. Each time concrete was poured, HD staff were supposed to first check that the quantity of concrete delivered to the site matched the reported volume of the pile concerned. The night work ensured that the concreting of 30 out of the 36 piles escaped the supervision of HD staff.
In line with the contract, Hui Hon employed a quality control engineer to inspect every item of works to ensure compliance. The quality control engineer told ICAC investigators that he was supposed to conduct quality control at the Yuen Chau Kok site, but in fact spent most of his time at another construction site. He said that the two ex-directors of Hui Hon were aware of his heavy work load.
Over a period of several months, he carried out very few inspections at Yuen Chau Kok site. He admitted that he had signed a number of confirmation documents without having actually checked the quality of the works. He was merely a rubber stamp.