TasWater

Rosebery is a remote township located on the west coast of Tasmania, approximately 300 kilometres from Hobart. The town is set in rugged terrain at the foot of Mount Black, within the West Coast Range, and is surrounded by temperate rainforest and high-rainfall catchments. The environment surrounding Rosebery, including the Pieman River system and adjacent rainforest reserves, is highly
sensitive, requiring careful management of discharges. Average annual rainfall in Rosebery exceeds 2m.

Factor UTB was engaged by TasWater to design and construct a new sewage treatment facility at Rosebery, with specific consideration given to the extreme inflow and infiltration (I&I) characteristics of the catchment. Daily inflows vary significantly, with dry summer periods producing less than 300 kL/day, while during the wet season flows can exceed 4 ML/day.

The facility was designed with advanced nutrient reduction capability to ensure compliance with stringent environmental requirements. This was essential as the plant’s outfall discharges to the Pieman River, which flows through the man-made hydroelectric impoundments of Lake Rosebery and Lake Pieman before reaching the Southern Ocean. Protecting these sensitive water bodies, and the downstream marine environment, was a key driver in the treatment design.