Blue−green drainage infrastructure in Hung Shui Kiu/Ha Tsuen New Development Area, Hong Kong

The Civil Engineering and Development Department (CEDD) of the Government of the Hong Kong Special Administrative Region of the People’s Republic of China used a HK$10.8 million (£1 million) NEC3 Professional Services Contract to deliver a pioneering feasibility study for Hong Kong's first blue-green drainage infrastructure at the Hung Shui Kiu/Ha Tsuen New Development Area. Completed in 2022, the study used NEC-inspired collaboration across multiple government departments to resolve novel management and maintenance challenges for multi-functional infrastructure that serves as recreational open space in normal conditions and stormwater attenuation during extreme rainfall - a design approach entirely new to Hong Kong at the time. 

Hong Kong's first blue-green drainage feasibility study 

Hung Shui Kiu/Ha Tsuen is a planned new-generation new town in the northwestern New Territories that will eventually accommodate a substantial population. Its drainage infrastructure was planned from the outset as a blue-green system - combining conventional drainage engineering with ecological and recreational functions. CEDD engaged AECOM Asia under a NEC3 PSC in December 2018 to develop a preliminary scheme, design criteria and implementation strategy for the blue-green infrastructure across the new town. 

The study proposed a flood retention lake within the planned 16 ha Regional Park, designed with water and landscape features providing a micro-climate cooling mechanism and biodiversity enhancement, while also attenuating peak surface runoff during extreme rainfall. Recreational spaces including football pitches, basketball courts and tennis courts were designed as floodable open spaces, providing stormwater retention capacity during severe weather while functioning as community amenities in dry conditions. River channels and embankments were to be revitalised for both hydraulic capacity and biodiversity. The co-use of land to combine leisure, biodiversity and flood attenuation in a single area was a first for Hong Kong. 

Multi-department collaboration on unconventional infrastructure 

Chung Lok-chin, chief engineer of CEDD West Development Office, says the project team's most significant challenge was resolving the management and maintenance responsibilities for infrastructure that would be shared across multiple government departments, each responsible for a different operational aspect. As the operation and maintenance of large-scale multi-functional blue-green infrastructure was entirely new to Hong Kong, NEC risk reduction meetings were held from an early stage to identify potential issues and formulate action plans with mitigation measures, including early involvement of all stakeholder departments. 

Drainage Services Department collaborated fully throughout, providing expert advice on all proposals. Numerous workshops were held with all other relevant departments to understand their concerns and ensure the infrastructure would function correctly across its design life. The consultant compiled a discussion paper incorporating all stakeholder input to build support and agreement for the proposed approach. CEDD also proactively sought local examples of emergency response procedures for analogous infrastructure - including action plans for storm surges at Tai O - to develop a joint contingency plan agreed between emergency response departments, flood warning system operators and maintenance agencies. Chung concludes that the outcome was a proof of how a project team could truly act in the NEC spirit of mutual trust and co-operation. 

The project team swiftly established a common objective to smooth the timely implementation of the flood attenuation facilities. NEC-inspired collaboration was vital for the study as the operation and maintenance of large-scale multi-functional blue-green infrastructure was unconventional in Hong Kong. The successful outcome of the study was a proof of how a project team could truly act in the NEC spirit of mutual trust and co-operation.

Chung Lok-chin, Chief Engineer, West Development Office, Civil Engineering and Development Department, HKSAR 

Benefits of using NEC 

• The NEC3 PSC provided the appropriate collaborative contractual framework for a feasibility study requiring sustained engagement with multiple government departments on an entirely new type of infrastructure for Hong Kong. 
• NEC risk reduction meetings, held from an early stage of the study, enabled all potential management and maintenance issues to be identified and action plans formulated before they could affect the study's programme or outputs. 
• NEC-inspired collaboration extended to proactive stakeholder engagement - including seeking emergency response examples from analogous infrastructure elsewhere in Hong Kong - to build the cross-departmental consensus needed for novel multi-functional drainage infrastructure. 
• The NEC spirit of mutual trust and co-operation enabled the consultant to compile and integrate input from all stakeholder departments into a single agreed discussion paper, transforming potential interdepartmental conflict into a shared vision for the new town's drainage infrastructure.