Clough was commissioned by Placer Exploration Limited to design and construct the Perry River Weir as part of Placer’s exploration program in Queensland. 

The roller compacted concrete (RCC) construction method was selected for this project for several reasons, including its robust water retaining properties, significant reserves of strength in comparison with earth dams and substantial cost advantages over mass concrete techniques.

Due to the varying degrees of weathering of the granite foundation, detailed seam treatment was required, causing the initial construction phase to take longer than expected. Once full layers could be built, construction proceeded rapidly, with two 300 mm layers being completed each day. The reliability of the design was highlighted during the construction phase, when heavy rains caused the half-completed weir to be overtopped by 1.5 metres of water, without causing any damage to the structure, even though the topmost layer was only hours old. 

To attain the required degree of water retention in the RCC structure, the Project Team paid close attention to achieving a high degree of uniformity in the graded concrete product. With segregation being a major cause of increased permeability and decreased structural strength, Clough engaged the services of specialist subcontractors to assist with key aspects of the design and construction.