Owned and operated by GMW, Newlyn Reservoir is located in the Central Highlands of Victoria, approximately 30 km northeast of Ballarat. It sits on Birch Creek, a tributary of Tullaroop Creek. The reservoir is fed by a natural catchment that extends south to the Dividing Range, covering an area of around 66 km². The dam was initially constructed in 1871 and was upgraded in 1961 by raising the existing embankment and building a new secondary embankment, spillway, and outlet works. The spillway consists of a short unlined approach channel, an uncontrolled concrete ogee 5 m high, a concrete-lined chute, and a stilling basin. A dam safety review and subsequent risk assessment recommended the installation of piezometers beneath the spillway to determine the uplift profile, facilitating a better assessment of its stability under varying loading conditions.

GMW commissioned AECOM as the engineer for the project, which included designing and supervising the piezometer installation. Geological Consulting acted as a subconsultant to AECOM for the works. The scope of work included the installation of nine Vibrating Wire Piezometers (VWP) in five boreholes, which were drilled through the concrete structures and into their foundation. Dam safety during drilling and the installation of the piezometers was a key consideration, as the reservoir remained operational throughout the works.  Risk management was undertaken following industry guidelines for drilling in and around dams (ANCOLD 2020).  Secondary objectives of the investigation included confirmation of the as-built details and current condition of the concrete structures (via large-diameter concrete coring) and further characterisation of the dam foundation materials (including in-situ testing and undisturbed sampling).