Table 2 – Assumptions of construction and liner details for waterway Waterway section Construction method Permanent & support lining class Headpond Concrete Headpond dropshaft Concrete Headpond dropshaft Drill and blast Unlined rock Main headrace tunnel TBM Unlined rock Main headrace tunnel TBM Shotcrete Downstream dropshaft Drill and blast Concrete High pressure headrace tunnel Drill and blast Concrete High pressure headrace tunnel Drill and blast Steel Penstock & PS Steel Tailrace Cut and cover Concrete