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二零零八年十二月十日 政府就「沙井爆炸事故與安全事宜」之書面回覆 (轉戴自: http://www.info.gov.hk/gia/general/200812/10/P200812100104.htm)
立法會九題：沙井爆炸事故與安全事宜
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以下是運輸及房屋局局長鄭汝樺今日（十二月十日）在立法會會議上就譚偉豪議員的提問所作的書面答覆：
問題︰
鑑於近年有多宗在沙井發生的爆炸事故，政府可否告知本會：
（一）過去五年有多少宗沙井爆炸事故；每宗事故的地點、起因、所引致的傷亡人數（當中有多少人是公用事業機構的人員），以及肇事沙井所屬機構；
（二）過去三年有否研究如何減少該等事故；若有，研究結果及具體措施為何；若否，原因為何；
（三）會否對全港的沙井進行爆炸風險評估；若會，落實時間表及有關的開支為何；若否，原因為何；
（四）有否研究可否截封連接沙井的管道旁的氣孔，以防止可燃性氣體從那些氣孔滲入沙井而釀成爆炸；若有，研究結果為何，以及會否立法強制公用事業機構執行；若否，原因為何；
（五）過年三年，有否評估電纜故障所引致的沙井爆炸事故的趨勢；若有，詳情為何；若否，原因為何；及
（六）有何措施提高政府及公用事業機構的人員在沙井工作時的職業安全？
答覆：
主席︰
（一）根據有關政府部門的紀錄，過去五年曾發生六宗沙井爆炸事故，詳情見附表。
（二）、（三）及（四）路政署於二○○八年五月完成一份名為《預防公共事業沙井氣體爆炸》的研究（研究），透過調查不同種類的沙井，評估公共道路上沙井的爆炸風險，以及研究相關的預防措施。研究的開支約為600,000元，研究就不同公共事業的沙井的氣體爆炸風險，有以下的結論－
（i）爆炸性氣體進入電訊設施的沙井的風險較高，原因是這些沙井數量多、裝設的深度較淺，而且連接至這些沙井的聚氯乙烯喉管較容易受損毀；
（ii）煤氣沙井的爆炸風險亦相對較高，原因是煤氣有可能從煤氣喉管泄漏，以及與沙井的內部設計有關；
（iii）爆炸性氣體進入污水設施的沙井的風險相對較低，原因是污水渠已被密封。然而，風險仍然存在，因為污水可能會產生爆炸性氣體，而污水設施的沙井並無通風設備；
（iv）排水設施的沙井的爆炸風險為低，原因是集水溝提供了通風的功能；
（v）電力設施的沙井的爆炸風險為低，原因是這種沙井已填滿，並且沒有設置電纜；及
（vi）水務設施的沙井的爆炸風險為低，原因是水管已被密封，而且喉管與沙井內的牆壁沒有空間，因此爆炸性氣體不能進入。
研究提出了下列四項措施，以減低沙井氣體爆炸的風險－
（i）密封連接至沙井的喉管，以防止爆炸性氣體進入沙井並在該處積聚；
（ii）把沙井內的空間以較輕和防火的袋裝物料填滿，以防止過量爆炸性氣體積聚；
（iii）連接沙井至通風口或為沙井裝設有通風口的井蓋，為沙井通風；及
（iv）為沙井的井蓋安裝抑制裝置，以防止井蓋因爆炸而大幅度移位。
當局已將研究的結果轉交有關的政府部門，以及公共事業機構和監管機構，以作出跟進。公共事業機構對確保轄下設施的安全有一般謹慎責任，因此，當局在現階段無計劃就強制實施以上的建議引入新的法定規定。
除了改善沙井安全，機電工程署也加強了措施，以減少煤氣泄漏的機會。香港中華煤氣公司（煤氣公司）已於二○○六年起增加為全港的地下中壓墨鐵喉管進行例行探漏的次數，由原來的每年三次增加至每年六次；煤氣公司亦已有計劃安排更換中壓墨鐵喉管為抗漏性更佳的聚乙烯喉管。此外，機電工程署也加強了定期巡查和突擊抽檢。
（五）根據紀錄，過去在三年並沒有發生因地下電纜故障而造成的沙井爆炸事故。
（六）沙井工作的安全主要受到勞工處執行的《工廠及工業經營（密閉空間）規例》（第59B章）（規例）所規管，規例訂明在密閉空間工作的安全要求，包括由合資格人士進行風險評估，以及工人須接受認可安全訓練。為了執行規例，勞工處會巡查密閉空間工作，其中包括渠務工程，勞工處亦會安排在晚間渠務工程較多時進行突擊巡查，以及在雨季期間進行特別執法行動。任何東主或承建商違反規例可處罰款 200,000元或監禁十二個月。
勞工處亦透過出版皷物，向有關持責者提供實務指引，推動恪守規例，這些皷物包括《密閉空間工作的安全與健康工作守則》、《沙井工作安全簡介》及《預防渠務工程氣體中毒事故》。此外，勞工處亦定期舉辦推廣活動及健康講座，以加強沙井工程承辦商及工人的職安健意識。
完
２００８年１２月１０日（星期三）
香港時間１６時２４分
December 10, 2008 Written reply regarding "Incidents of explosion in manhole" (Quoted from: http://www.info.gov.hk/gia/general/200812/10/P200812100118.htm) LCQ9: Incidents of explosion in manhole
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Following is a question by the Dr Hon Samson Tam and a written reply by the Secretary for Transport and Housing, Ms Eva Cheng, at the Legislative Council meeting today (December 10):
Question:
As there were a number of incidents of explosion in manhole in recent years, will the Government inform this Council:
(a) of the number of incidents of explosion in manhole in the past five years; the location, cause and resultant casualties (together with the number of staff of public utility organisations among them) of each incident, as well as the organisation to which the manhole belonged;
(b) whether it has studied in the past three years ways to how such incidents could be reduced; if so, of the study results and specific measures; if not, the reasons for that;
(c) whether it will assess the explosion risks of all manholes in Hong Kong; if it will, of the implementation timetable and related expenses; if not, the reasons for that;
(d) whether it has studied the feasibility of sealing off holes surrounding the pipelines connected to manholes, so as to prevent explosion caused by inflammable gas leaking into the manhole through such holes; if it has, of the results and whether it will legislate for mandatory enforcement by public utility organisations; if not, of the reasons for that;
(e) whether it has assessed the trend in explosion in manhole caused by power line failure in the past three years; if it has, of the details; if not, the reasons for that; and
(f) what measures are in place to enhance the occupational safety of staff of the Government and public utility organisations when they are working in the manholes?
Reply:
President,
(a) According to the records of the concerned Government Departments, there were six manhole explosion cases in the past five years. The details are attached (see Annex).
(b), (c) & (d) In May 2008, Highways Department completed a consultancy study "Prevention of Gas Explosion in Utility Manhole" ("the Study") to assess the risk of manhole explosions in public streets, through surveying a number of different types of manholes, and study the relevant preventive measures. The cost of the Study was around $600,000. The general findings on the risk of gas explosion in various types of utility manholes are as follows –
(i) the risk of explosive gas entering manholes for telecommunication facilities are generally higher given the large number of such manholes, their shallower depth of installation, and that the polyvinyl chloride ductings leading into these manholes are more susceptible to damage;
(ii) the risk of explosion in Towngas manholes is also relatively high owing to the possibility of leakage from Towngas pipes and fittings inside the manhole;
(iii) the risk of explosive gas entering sewer manholes is relatively low since the sewers are sealed. However, the risk still exists because sewage may produce explosive gas and sewer manholes have no ventilation;
(iv) the risk of explosion in drainage manholes is low since the connecting gullies provide ventilation;
(v) the risk of explosion in electricity manholes is low since they are filled and do not have underground power supply lines inside; and
(vi) the risk of explosion in water supply manholes is low since water pipes are sealed and there is no gap between the pipe and the manhole walls to allow explosive gas to enter.
The Study identified the following four measures to reduce the risk of gas explosion in manholes –
(i) sealing up ducts leading into manholes to prevent explosive gas from entering and accumulating inside manholes;
(ii) filling up the empty space inside manholes with bags of light-weight, flame-retardant materials to prevent excessive volume of explosive gas from accumulating;
(iii) ventilating the manholes by connecting them to vents or installing manhole covers with vent openings; and
(iv) installing restraints to manhole covers to prevent them from large displacement in case of an explosion.
The results of the Study have been presented and passed to the concerned Government departments as well as the utility undertakers and their relevant controlling authorities for follow-up actions. Utility undertakers have a common duty of care to ensure that their facilities are safe. As such, there is no plan at this stage for introducing new statutory requirements regarding the mandatory application of the above recommendations.
In addition to improving the safety of manholes, the Electrical and Mechnical Services Department (EMSD) has stepped up measures with a view to reducing the possibility of gas leakage. The Hong Kong China Gas Company (HKCGC) has since 2006 increased the number of routine leakage surveys for all underground medium pressure ductile iron (MPDI) pipes in Hong Kong from 3 times to 6 times per year. HKCGC also has a programme for replacing MPDI pipes with polyethylene pipes which are better in resisting gas leakage. Moreover, EMSD has strengthened regular inspections and surprise checks.
(e) According to the records, there has been no manhole explosion incident caused by power line failure in the past three years.
(f) Work safety in manholes is governed mainly by the Factories and Industrial Undertakings (Confined Spaces) Regulation (Cap. 59B) (the Regulation), administered by the Labour Department (LD). The Regulation sets out the safety requirements for working in confined spaces. These include requirements for risk assessment to be carried out by competent persons and for workers to undergo approved safety training. In enforcing the Regulation, LD conducts inspections of works at confined spaces, including drainage works. LD also conducts surprise inspections at night, when drainage works are commonly conducted, and launches special enforcement campaigns during the rainy seasons. A proprietor or contractor who contravenes the Regulation is liable to a maximum fine of $200,000, and to imprisonment for 12 months.
LD also promotes compliance with the Regulation through publications to provide practical guidance to duty holders. These include the "Code of Practice for Safety and Health at Work in Confined Spaces", "Safety Guide for Work in Manholes" and "Prevention of Gas Poisoning in Drainage Work". In addition, publicity and health talks are also regularly organised to enhance the occupational safety and health awareness of contractors and workers in such works.
Ends/ Wednesday, December 10, 2008
Issued at HKT 16:25
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