The finished project will have a sewage treatment capacity of 340,000cu.m per day, serving a population of 800,000 in the Sha Tin area.

An Aecom spokesman said, "Aecom’s scope of works includes engineering and environmental impact assessments, design of sewage treatment process, all aspects of engineering and architectural design in relation to the sewage treatment works in caverns, preparation of tender documents and construction supervision. Aecom will also assist the government in public engagement activities and provide preliminary design for the upstream sewerage networks and pumping facilities related to the relocation of the STSTW to caverns.

"To design a sustainable sewage treatment works located inside caverns that will meet the demands for the next several decades, Aecom’s cavern and process teams will work out advanced sewage- and sludge-treatment technologies to minimise the size of needed caverns, energy consumption, carbon footprint and sludge production, in order to optimize the cost of the entire life cycle."

"Aecom will organise pilot studies to ensure that state-of-the-art technologies work well for local sewage characteristics, including high salinity due to the use of seawater for flushing in Hong Kong."

The investigation and design work are scheduled for completion in phases from 2017, and construction works will commence afterwards.