Hadleys were involved in the design, tendering and project management of three snowmaking reservoirs at Coronet Peak Ski Area – Rocky Gully, Elephant Pit and Sarah Sue – in order to expand their snowmaking facilities.
The 3 HDPE lined reservoirs enabled an additional 160,000m³ of water storage. This water is then dispersed to over 200 snow guns through over 60km of water and compressed air pipework and power cabling, allowing Coronet Peak to make sufficient snow to provide 0.5m cover to all main trails over the entire ski area. The reservoirs and snow making infrastructure were constructed over 3 summer construction periods and represents the largest snowmaking facility in the Southern Hemisphere.
Coronet Peak is located at an elevation of approximately 1,600m. It is an alpine environment located on an aged landslide and is approximately 15km from the Alpine Fault. The most efficient form of water storage was determined to be achieved by developing existing natural depressions. Preliminary analysis was performed across the site (comprising approximately 280ha) to identify potential reservoir sites using test pitting, core drilling and material testing.
Due to the risk associated with water impoundment structures, all three reservoirs were the subject of detailed site investigation work comprising geological mapping, material testing (including Ring Shear and Triaxial testing) and borehole testing comprising core recovery and SPT testing.
The Sarah Sue Reservoir is the largest of the three and involved over 50,000m³ of earthworks. Due to the complications of the site, including the active landslide and weak fluvial materials underlying the site, construction was staged between two summers. This allowed us to preload the potentially weak subsurface material over an extended period of time while performing detailed survey monitoring. After satisfactory settlement results the second stage of construction was performed. This project had many challenging aspects with high altitude conditions, short construction seasons, complicated geology and was commissioned on time for the snowmaking season and under budget.
Coronet Peak, Queenstown