AJ Project

Alaska, United States of America

Related Clients

Years of Service

1989 to 1994

Project Description

The proposed AJ mine will be an underground gold mine with an ore production of 22,500 tons per day.

Dr. Robertson was working with SRK when they were commissioned to investigate the technical and economic feasibility of six alternative tailings disposal sites, together with alternative methods of dam construction. Studies showed that a site on Sheep Creek approximately 4 miles southeast of Juneau offered significant advantages over the other sites.

A roller compacted concrete (RCC) dam with a final height of 335 feet was selected as providing the safest and most economical structure. It will also allow staged construction over a 13 year period to reduce initial costs. An inexpensive arrangement for a multi-level intake tower and overflow spillway is provided. To preserve water quality in the lower reaches of Sheep Creek, all excess water from the impoundment except major floods will be discharged through a pipe to the ocean. The design includes an option for using the same pipe as a penstock for a 5 MW hydroelectric generating plant located near tidewater.

Services Provided:

  • Site selection, comparative assessment and site ranking of potential tailings sites.
  • Hydrology studies and evaluation of hydro-electric potential.
  • Foundation investigations for RCC dam.
  • Detailed design of RCC dam, spillway, intake structure and stilling basin.
  • Development of detailed cost estimates.
  • Preliminary routing of tailings and water reclaim pipelines.