Siu Ho Wan Water Treatment Works extension, Hong Kong

The Water Supplies Department (WSD) of the Government of the Hong Kong Special Administrative Region (HKSAR) of the People’s Republic of China used NEC4 Engineering and Construction Contract (ECC) Option C (target contract with activity schedule) to double the treatment capacity of the Siu Ho Wan Water Treatment Works on Lantau Island, from 150,000 to 300,000 m³ per day, serving the rapidly growing Tung Chung New Town and Hong Kong International Airport. The HK$2,065 million (£216 million) extension, contracted to China Road and Bridge Corporation in March 2022, incorporates advanced ozonation and two-stage filtration technology alongside a zero-discharge wastewater recycling system and a digital twin for process optimisation. The project won three awards at the CIWEM Hong Kong 2024 Innovation and Sustainability Awards.

Doubling capacity with advanced treatment technology 

The existing Siu Ho Wan works, opened in 1996, must double its capacity to meet the planned population growth of Tung Chung New Town Extension and associated developments by 2028. The extension involves constructing a new multi-level water treatment building and office and laboratory building, modifying existing facilities and installing a new raw water booster pumping station to increase supply from a nearby reservoir. Advanced treatment technology has been adopted throughout, including pre-ozonation ahead of dissolved air flotation clarification, intermediate ozonation, two-stage filtration and chlorine disinfection. 

Environmental innovation runs throughout the project. All process wastewater is treated and recycled to achieve zero discharge. A rooftop photovoltaic system supplements electricity supply, variable speed pumps reduce energy consumption, and a digital twin will simulate the entire treatment process in real time, enabling cost-effective operation by optimising supply and demand management, pump configuration and chemical dosage. Safety on site is supported by smart watches providing continuous health monitoring of workers and closed-circuit television with artificial intelligence detecting unsafe behaviours. The works are being completed in stages from mid-2025, with Binnies Hong Kong Limited serving as the client's designer and NEC supervisor. 

Building a collaborative team from the outset 

Percy Hau, Chief Engineer of the WSD Consultants Management Division and NEC project manager, says creating a genuinely collaborative environment across the client, project manager and contractor was central to the project's delivery approach and directly aligned with NEC's requirement to act in a spirit of mutual trust and co-operation. 'The project team has made a concerted effort, which includes working in a joint site office, wearing site uniforms with the same project logo, and holding weekly partnering meetings, regular team-building events and partnering workshops so as to promote collaborative spirit.' 

Hau says the NEC early warning process was the primary tool for managing the particular challenges of constructing a major extension within a live, fully operational treatment works with very limited space. Where two new 1.2 m diameter water mains had to be routed adjacent to an existing barrack, safety and access issues were raised in an early warning meeting. With no alternative alignment available, the project team proactively arranged for the barrack to be temporarily relocated, allowing construction and plant operations to run in parallel. The contractor was fairly compensated through a compensation event. Similarly, where no contractual obligation existed for the client to provide temporary storage, the project manager liaised with neighbouring government installations to secure 1,370 m² of land for contractor use. 'We have endeavoured to foster a collaborative environment, comply with NEC requirements and encourage the use of innovative technology. These efforts are critical in ensuring successful completion of the project within the agreed programme and budget.'

We have endeavoured to foster a collaborative environment, comply with NEC requirements and encourage the use of innovative technology. These efforts are critical in ensuring successful completion of the project within the agreed programme and budget.

 Percy Hau, Chief Engineer, Consultants Management Division, Water Supplies Department, HKSAR

Benefits of using NEC 

• NEC4 ECC Option C provided fair risk sharing for a technically complex, phased extension to a live operational water treatment works, enabling client and contractor to manage the constraints of the site collaboratively from the outset.
• The NEC spirit of mutual trust and co-operation underpinned a joint working environment, with a shared site office, shared project identity and regular partnering workshops keeping the entire project team aligned throughout the programme.
• NEC early warning processes enabled proactive identification and collaborative resolution of spatial and logistical challenges on a severely constrained brownfield site, avoiding delays and ensuring fair remuneration through compensation events.
• NEC's compensation event process provided clear, transparent valuation of scope changes throughout, supporting cost certainty on a staged programme running to 2028 and underpinning the trust needed for genuinely collaborative delivery.