PROJECTS

Drury Quarry

Client: W Stevenson & Sons Ltd
Contractor: Metso Minerals, Rocktec, Stevenson's
Consultant: Peters & Cheung Ltd.
Completed: May 2003

W Stevenson & Won Ltd have recently upgraded the production capacity of their Drury Quarry with the installation of additional primary and secondary crushers, screening plant, hoppers and conveyors.

Peters and Cheung designed and carried out the construction observation of 1500 square metres of Keystone retailing walls of up to 11m high, as well as the building platforms and foundations for the new works.

Peters & Cheung were appointed to design the civil works for the project including carrying out geotechnical investigations, developing the site layout, designing the large multi-level building platforms, the haul roads, retaining walls and plant foundations and carrying out construction observation.

The site is located mid-way up a very steep greywacke hill slope with a 6m thick veneer of completely weathered soil and highly weathered fractured rock layer. A key aspect of the design included determining safe cut slope angles and carrying out slope stability analyses for the building platforms.

The project requires 1500 square metres of Keystone retaining walls of up to 11m high. The walls have been designed for heavy dump trucks with axle loads of up to 100 tonnes which back up to the edge of the Keystone walls. Steel ladders were chosen to reinforce the soil block behind the retaining walls. These ladders are not galvanised. The design allows for the loss of steel due to corrosion over the one hundred year design life of the retaining walls.