ENG-2006 — Page 289

Land, Public Works and Utilities | 237

In addition, the department provides construction materials testing and ground investigation services to support public works projects. The testing service is provided by the Public Works Laboratories. During the year, some 700 000 tests were carried out and 30 000 metres of soil and rock drilled.

Mining and Quarrying

The department enforces legislation relating to mining, quarrying and explosives, and deals with quarrying contracts. It processes applications for the manufacture, storage, conveyance and use of explosives, and inspects stone quarries, blasting sites. and explosives stores.

Hong Kong used up about 11 million tonnes of aggregates and other rock. products in 2006. About 55 per cent of its demands was provided locally. The rest was from the Mainland.

Three quarrying contracts were in force during the year. These require the operators to rehabilitate the quarries within a specified period in return for the granting of rights to process and sell surplus rock excavated during the course of the works. The rehabilitation works involve recontouring the quarries and planting trees and shrubs on them to make them blend with the surrounding hillsides.

The department manages two government explosives depots at Kau Shat Wan on Lantau Island and on Piper's Hill, Sha Tin, which provide bulk storage facilities for imported explosives for industrial use. It also transports the explosives from the depots to the blasting sites and issues shot-firer certificates. About 820 tonnes of explosives were used in 2006 for quarrying and site formation.

In addition, the department helps the Home Affairs Bureau and the Marine Department to assess applications for fireworks displays.

Fill Supply and Mud Disposal

About 6.5 million tonnes of construction and demolition (C&D) materials were received at the public fill reception facilities during the year. In addition, about three million tonnes of inert C&D materials were used directly in other projects. The CEDD, on behalf of the Public Fill Committee (PFC), is involved in drawing up strategy for managing public fills. It also helps coordinate the reuse of C&D materials. Construction companies are required to reduce the generation of waste materials at source. Following the introduction of the Construction Waste Disposal Charging Scheme, two construction waste sorting facilities were set up in Tuen Mun and Tseung Kwan O in January 2006 to facilitate the reuse and recycling of C&D materials.

In 2006, about 1.1 million cubic metres of uncontaminated mud and 650 000 million cubic metres of contaminated mud were generated by various works projects and by maintenance works on navigational channels in the harbour. The uncontaminated mud was dumped in the open sea or in exhausted marine sand borrow pits. The contaminated mud was placed in selected and closely monitored exhausted sand borrow pits, which were then capped with clean mud. The use of exhausted sand borrow pits for mud disposal is preferred as it has the twin benefits