In 2005, Black & Veatch Hong Kong Limited (B&V) was commissioned by the University of Hong Kong (HKU) to provide engineering services for the proposed HKU Centennial Campus expansion on a site occupied by fresh and salt water service reservoirs of the Water Supplies Department (WSD). To provide land for the campus expansion, the project team consisting of WSD, HKU and B&V conceived an innovative idea to house two salt water service reservoirs in a cavern inside Lung Fu Shan hillside. Locating service reservoir in a cavern was the first time in Hong Kong’s engineering. The scheme significantly reduced slope cutting, site formation and tree felling; avoided disturbance to the existing habitat and minimised visual impact to the neighbourhood. It also helped preserve three graded historic buildings. The approach also enabled its implementation by Gammon Construction Limited to be environmentally friendly with reduction in dust, noise impacts and the generation of construction and demolition materials.