Despite all the obstacles at Yuen Chau Kok, Hui Hon could not afford any delays and often skipped the correct procedures. The site agenttold the ICAC investigators, for example, that in order to speed the work up, he had asked workers to drop the temporary casings into the pile shafts instead of installing them properly.
The site agent resorted to using yet more shortcuts. When cleaning the pile shafts, instead of running the tremie pipes right down to the bottom to completely flush out debris or silt, he asked the workers to run the pipes only halfway down the pile shaft.
This avoided stirring up the debris at the bottom, so guaranteeing that the flushing water from the shaft would soon run clear. The site agent could then report to the HD that the cleaning process had been properly completed, when in fact it had not.
He maintained that it was in no way wrong of him as an employee to do what his boss told him to. When he had conveyed his concerns about various problems to his boss and other colleagues, his boss had insisted that things should be done his way. If the site agent wanted to keep his job, he had better follow instructions.
In fact, the site agent carried on forging various test results and records over and over again, and matters soon snowballed. Mr Leung recollected, “This man claimed that he was just following the instructions of his boss, but he had underestimated the consequences of his actions.”
After concreting, each pile had to go through tests laid down by HD in order to verify both the integrity of the concrete and the length of the pile. All large diameter bored piles were required to pass a sonic test. Once Hui Hon reported that all the concreting had been completed, HD hired a contractor to conduct sonic tests, as stipulated in the contract.
When questioned by an ICAC officer, the testing officer said that the piles of two buildings at the Yuen Chau Kok site had been tested between July and October 1998. He discovered that most of the sonic tubes in 18 of the piles were blocked. Some tubes were blocked at their very top, making it impossible to insert the test probe. The HD site staff considered that such blockages had been caused by faulty tube installation and they requested Hui Hon to come up with remedial measures.
On 23 September 1998, however, Zen Pacific took charge of the project with Hui Hon’s site agent still on the job. The site agent now suggested to HD that vibration tests should be carried out in addition to the planned core tests.
The contract required core tests to be conducted on 5 percent of all piles to verify their length and the integrity of the concrete. These tests are both costly and time-consuming, and all core samples extracted from the piles must be kept in a secure place to avoid any tampering.
In fact, many of the core samples in these boxes had already been faked. The site agent explained that if a core sample contained mud and debris or showed honeycombing, he would simply ask his subordinates(site foreman and assistant engineer) to have the workers extract a replacement core sample from a pile of known good quality. The workers responsible for core extraction agreed that these were indeed the instructions they had received.
The site agent assembled different cores extracted from piles of the correct quality to replace poor quality cores obtained from the substandard piles. By measuring the total length of the cores, including the counterfeit ones, he falsified core sample records, thus concealing the existence of the substandard piles. The workers who extracted the core samples told investigators, however, that Hui Hon staff put the boxes of extracted core samples in unlocked boxes in the car park outside HD’s site office. This arrangement could have provided ample opportunities for changing the core samples.
When more than the stipulated quantity of cores had been extracted from a pile that was up to standard, the number of drill holes in that pile could have aroused suspicion. The site foreman said that his supervisor (the site agent) asked him to cover any superfluous drill holes with wooden planks to prevent the fraud being discovered by HD staff during inspection.
Quite a number of core tests had been conducted on the completed piling for the first of the two buildings with satisfactory results. HD therefore agreed to the site agent’s proposal that core tests for the second building should be carried out on only two piles out of the total of 18, although all 18 piles would be subject to vibration tests. This arrangement was presented as a time saving measure.
It was also an arrangement that opened the way to yet further deception. The site agent employed a contractor to conduct vibration tests on the designated piles in late October 1998. However, a witness stated that the testing staff were deliberately steered towards piles that were in fact known to have met standards. This contractor’s eventual conclusion was as follows: “The piles are proven continuous to the pile toe and are therefore regarded as being of acceptable integrity.”3
3Translated from the Legislative Council Select Committee Report on Building Problems of Public Housing Units, p. 107