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Following is a question on measures to control the use of explosives at construction sites by the Hon NG Leung-sing and a written reply by the Secretary for Works, Mr Lee Shing-see, in the Legislative Council meeting today (Wednesday) :

Question :

It was reported that fuses and explosives had been found buried in a construction site near Cityplaza, which were suspected to have been left behind years ago by construction workers who carried out blastings for slope cutting works there. In this connection, will the Government inform this Council:

(a) whether it has investigated the causes of the fuses and explosives being left there and the persons who should be held responsible for this; if it has, of the findings;

(b) of the number of cases in which explosives were unearthed at construction sites over the past five years;

(c) whether it has assessed the possibility of explosives being buried in other construction sites in Hong Kong, and if such explosives will endanger the safety of workers as well as the lives and property of residents in the neighbourhood; and

(d) whether it has assessed if the existing measures to control the use of explosives at construction sites are adequate and effective?

Reply:

Madam President,

(a) The construction site referred to by the Honorable Mr. Ng Leung-sing is located under the flyover at the intersection of Kornhills Road and King's Road in Quarry Bay. Blasting works were carried out at the site for development of the Kornhills housing project during 1982 and 1986. In the current incident, two pieces of broken wires, each 200 mm long and protruding out of a 50 mm diameter drill hole, were found at the site. The colour of the wires (one red and one white) matched the lead wires used for the blasting for the Kornhills project. We believe that the broken wires are the remains of the lead wires from the previous blasting. However, no detonator nor explosives was found. To ensure safety, the Police (Explosives Ordnance Disposal Bureau) conducted a controlled explosion in the area suspected to contain explosives. The limited effect of the controlled explosion during the disposal demonstrated that there was no explosives left from the previous blasting at that location. Therefore the question as to who should be responsible for leaving behind any explosive does not arise in this case.

(b) In the past five years, over 18,000 blasting events, totaling over 500,000 drill holes, were conducted. During this period, there was only one case in which an un-exploded cartridge explosives was found after completion of blasting work. In 1995, a cartridge explosives together with a detonator were found on a construction site. The detonator had already detonated whereas the cartridge explosives had deteriorated. The cartridge explosives was subsequently removed by the Mines and Quarries Division of the Civil Engineering Department for destruction. In fact, within the last 10 years, this is the only case of this nature.

(c) The possibility of leaving explosives from previous blasting at a blasting site is extremely rare. The shotfirer must search for misfire (i.e. unexploded explosives) immediately after each blast. Where misfire is found, the shotfirer must destroy the explosives in a proper manner. This requirement is in accordance with the Dangerous Goods Ordinance (Cap. 295). Such requirement will also be reiterated to the applicant and the shotfirer when blasting licence and Mine Blasting Certificate are issued, respectively. The entire process of explosion, searching and handling of misfire is carried out under the supervision of the Mines and Quarries Division. Following the above procedures, the possibility of leaving explosives after blasting at construction is very low.

In practice, if the shotfirer found any unexploded explosives during the removal of the blasted rocks, he must first notify the contractor and the Mines and Quarries Division immediately. The shotfirer must report information on the amount of explosives, their trade name and type and acquire the approval of the Mines and Quarries Division on the proposed remedial measures prior to their implementation. In the event that such remedial measures cannot be completed within the same day, then the site must be sealed off, with a red flag displayed to warn people passing by the site. Also, the site will be constantly guarded by the contractor's security guards until all explosives are destroyed.

(d) The control on the use of explosives in Hong Kong is under the Dangerous Goods Ordinance (Cap. 295). The control is more stringent than that in many advanced countries such as United Kingdom, United States, Canada and Australia, due to the dense population in Hong Kong.

The regulatory control on explosives covers both safety and security aspects. Area under the control includes classification, manufacture, storage, conveyance on land, use and destruction. The regulatory approach in Hong Kong is quite different from other countries. In other countries, the user is allowed to store and transport explosives under the monitoring/supervision of the government. But in Hong Kong, the SAR Government is directly involved in such activities, carrying out storage and transportation of almost all explosives. Presently, the Government has nine explosives trucks, two explosives vessels and two explosives depots, with a capacity of 500 tonnes (located in Kau Shat Wan on Lantau Island) and 2 tonnes (located in Shatin) respectively.

At construction sites, the use of explosives is also monitored by government staff until all explosives is consumed.

Presently, only ammonium nitrate based explosives are allowed to be used at construction sites. Although other types of explosives such as black powder and nitroglycerine, etc. are still being used in other countries around the world, they are not used in Hong Kong. Ammonium nitrate based explosives are relatively less powerful but they are much more resistant to heat, impact and friction, and therefore the safety margin is greater.

Blasting can only be carried out by qualified personnel. To meet the requirements of the Mine Blasting Certificate, the applicant must have experience of at least 40 blasts (under the supervision of his master who is also qualified) and the recommendation of his master, as well as pass both a written and an oral examination.

Blasting work to be carried out at any construction site must be approved by the Mines and Quarries Division. Key elements of the approval process comprise site reconnaissance by our staff, establishing prelicensing requirements (for granting 'Permit to use', 'Licence to store') which include safety measures (e.g. screens, cages, mats, sandbags and evacuation procedures, etc.), method statements (e.g. quantities of explosives, area of blast, sequence, etc.) as well as qualifications of the relevant personnel. The applicant may also have to submit a blasting assessment report for the protection of properties, slopes and drainage works, etc. in the surroundings. Blasting can be carried out only after the contractor has fulfilled all the requirements and attended an interview with the Mines and Quarries Division. The amount of explosives to be used must be reported to the Mines and Quarries Division one day before the blast. During each blast, staff of the Mines and Quarries Division will be on site to supervise the use of the explosives with respect to safety and security.

Improved continuously and based on years of experience, the regulatory measures outlined above are now very comprehensive and effective. Nevertheless, blasting is inherently dangerous. Therefore, we will keep constant review on the regulatory measures and make any necessary improvements. Moreover, we will continue to exchange experience and ideas with our counterparts in other countries so as to maintain a high standard of safety and security in the use of explosives in Hong Kong.

End/Wednesday, 19 January, 2000

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