Climate change affects access to fresh water across the world, and Hong Kong is of no exception as the city's territory does not have natural lakes, large rivers or underground water reserve but largely depends on surface runoff and Dongjiang water from Guangdong, China. To diversify and build resilience for fresh water supply in Hong Kong, the Water Supplies Department (WSD) has planned a seawater desalination plant at Tseung Kwan O.
Located on an 8-hectare site, the first stage of the desalination plant will have a freshwater production capacity of 135,000 m3 per day, and with the provision to be expanded to an ultimate capacity up to 270,000m3 per day.
WSP, working closely with AJC Joint Venture, is providing multi-discipline engineering design services including civil, building services, architectural and landscape design as well as BIM management and BEAM Plus consultancy for this design, build and operate contract.
Innovative combined shaft
Considering the site constraints, our engineers has combined the intake and outfall shafts to become combined shaft, which will be located far away from the sloping seawall and hence minimising the impact on sloping seawall due to excavation and lateral support (ELS) works. Such arrangement can also lower the risk of tunnelling works hitting seawall armours or rockfill. Since the water path from the wall of pit to the sea is lengthened, our design can ensure less seawater blow-in which will reduce the risk of flooding as it is away from the coping line.
Efficient BIM collaboration
The contract is a fast-track one with 39 months’ time for design and construction, yet the involvement of multiple stakeholders from several countries and regions makes it challenging to coordinate offline due to conflicting time zones, locations and common platform issues.
With a BIM-enabled platform featuring cloud-based common data environment, collaborators from all locations could synchronise project information with up-to-date models, which were federated as the master BIM model. Apart from achieving Level 2 BIM in design, checking and submission processes, WSP has combined the models with project schedule to visualise 4D phase planning, greatly improving the buildability of works.
The project has attained an honourable mention at Autodesk Hong Kong BIM Awards 2020 and a Silver Award at HKIBIM Awards 2020 for the successful collaboration on the first stage of Tseung Kwan O Desalination Plant. It has also been recognised as one of the ‘BIM Projects 2020’ in the Celebration of BIM Achievement 2020 organised by Construction Industry Council.
Genuine climate-proof infrastructure
While the desalination plant is set to enhance Hong Kong’s climate resilience with its unique function, the facility itself is designed and built to further contribute to a sustainable built environment.
Our engineers proposed a series of green features and a green building performance framework. It includes maximising the use of renewable energy in the treatment facilities, introducing rainwater harvesting for irrigation, solar panels for electricity generation, smart street lighting poles, roof greenery and vertical green walls. With the goal to minimise heat gain and carbon emission during the operation, we can significantly reduce the carbon footprint of the desalination plant.
We will also incorporate DfMA in the facade design of several buildings in support of Construction 2.0 to minimise on-site work, wastage of construction materials and potential pollution issues. With all these tailored design and methodologies, the desalination plant attained Provisional Platinum rating under local BEAM Plus green building certification, to be among the top-tier green public works.