With a total area of 1,092 square km and a population of 6.8 million people, almost 94 per cent of land in Hong Kong is already occupied – so when underground infrastructure requires repairs or general maintenance, simply digging to reach infrastructure is not always an option.

Further complicating matters is the fact that the majority of land is hilly to mountainous, with steep slopes, making conventional trenching techniques for laying and then maintaining underground infrastructure difficult.

The market for Trenchless Technology in Hong Kong is experiencing a period of rapid expansion. While a relatively new area to Hong Kong’s construction industry, investment in Trenchless Technologies are expected to steadily grow over the coming years.

In 1998, Hong Kong’s Water Supplies Department (WSD) first used Trenchless Technology on a large scale water mains installation program, sparking the current boom in no-dig techniques in Hong Kong. At present, the value of trenchless work in Hong Kong is expanding from a previously low base as business invests in trenchless equipment and expertise.

Contracts for works relating to Trenchless Technologies in Hong Kong are often subcontracted as a part of larger projects to companies which specialise in the field of Trenchless Technology. This is due to the fact that only larger, government-approved companies in Hong Kong can qualify to bid for sizeable civil engineering contracts, while companies that specialise in Trenchless Technology - which tend to be smaller, as the industry is still developing - are left to bid on the individual works involved with these projects.

Trenchless Technology specialists will also often secure contracts in their own right, due to the fact that such companies tend to own the equipment they use on jobs. The purchase of equipment is often linked to the procurement of a specific contract, which is largely due to the high costs associated with purchasing trenchless equipment.

Because the industry in Hong Kong is still small and developing, in the past contractors have partnered with overseas contractors to gain further expertise and a base with which to tap the Hong Kong market. In particular, German companies are well regarded both in Hong Kong and worldwide for their reputation for reliable technical support. Germany’s Herrenknecht dominates the microtunnelling market, Spiral Wound PVC is well regarded for close fit lining, and German products are often called on for pipe cleaning equipment, relining and pipe bursting.

Other sectors of the Hong Kong market have also been cornered by companies from countries aside from Germany, with Radiodetection from the UK holding a significant share of the market for detection equipment, and US-based Vermeer performing strongly in the field of HDD. US companies also have a majority market share in CCTV equipment and parts, compressors and boilers.

Case Study: Water Supplies Department Mains Replacement & Rehabilitation Program

Hong Kong’s fresh water and salt water supplies are provided through a network of 7,200 km of water mains, most of which are underground. Approximately 45 per cent of the water mains were laid 30 years ago and are now approaching the end of their service life, becoming increasingly difficult and costly to maintain.

As such, the Water Supplies Department is currently undertaking a program which will see approximately 3,000 km of the water mains rehabilitated and/or replaced.

This massive project will take place between 2000 and 2020 at a cost of $US1.3 billion. Due to its size, the project has been divided into sections by region, with the replacement and rehabilitation of water mains in Kowloon, one of the four main areas of Hong Kong, currently the focus for the WSD.

Important considerations for all sections of the project will include avoidance of unnecessary water supply disruption to consumers, avoidance of unnecessary traffic disruption during construction and cost effectiveness of the works, with priority to be given to water mains susceptible to leakage and bursting.

For the Kowloon section of the project, the WSD has identified 254 km of water mains to be replaced or rehabilitated, with further investigation into the project finding that approximately 75 km of additional water mains in the area were also due for replacement and/or rehabilitation.

The WSD plans to pre-drill holes using Trenchless Technologies, insert pipelines into the holes and connect these pipelines to supply points. After the new connections are established, the existing water mains will be abandoned.

While conventional mains replacement methods of opening trenches and laying new mains will be used where the traffic and environmental impacts arising from the works are not serious and when the underground utilities present are not congested, there will be sections of the project that will require the use of Trenchless Technology.

As Trenchless Technologies will be employed in some instances specifically to avoid Hong Kong’s already congested underground infrastructure network, the replacement water mains will be laid deep underground.

The main techniques the WSD will be relying on for replacement of mains are pipe ramming, pipe jacking and horizontal directional drilling, while the main techniques to be employed for rehabilitation will be the close fit lining method, the cured in place pipe method and the pipe bursting method.

Technical and design standards and specifications that are currently in use by Government Works departments and Transport Department will be adopted for the project. If such standards are not formally established, British Standard Codes of Practice and Specifications will be followed.

Two full sets of design calculations including a statement of the standards, procedures and codes of practice adopted will be submitted before the project begins, and each full set shall be accompanied by a certificate that the design calculations have been checked by another qualified independent designer.

Trenchless Australasia Magazine will continue to follow these developments in Hong Kong and report more in future issues.