Red Dog Mine is one of the world's largest zinc mines, located in the remote Northwest Arctic Borough of Alaska and operated by Teck Alaska, Inc. (TAK). Mine operations required the stockpiling of waste rock excavated from the first surface mine pit. The natural composition of the waste rock creates acid rock drainage (ARD) that is collected and treated by the mine before being discharged. TAK contracted Geosyntec to prepare a design of a cover system to minimize ARD. Because the mine is in a remote, artic region, the construction season and material delivery timeframe are typically limited to the summer, making design, construction, and oversight services particularly challenging.
Geosyntec's Scope of Services
Geosyntec developed a preliminary design for a geosynthetic cover system to be constructed on the Main Waste Stockpile (MWS) that contains waste rock generated from mining operations. The goal of the cover system is to minimize meteoric water that can infiltrate into the stockpile and thereby reduce the quantity of ARD that needs to be treated at the site. The cover system consists of a linear low-density polyethylene geomembrane, geocomposite and corrugated polyethylene pipe drainage system, and site cover soil. For the design, Geosyntec performed drainage analysis, cover system stability analysis, and site-specific materials testing.
To evaluate constructability of the cover system, Geosyntec also prepared a workplan to construct test plots over two construction seasons before implementing the full-scale design. The test plot workplan included a design for continuously monitoring the moisture profile of the cover system, recommended construction and geosynthetic installation procedures, and provided means to monitor and evaluate the effectiveness of construction procedures.
For the second test plot, which encompassed approximately 12 acres, Geosyntec performed a material cost-benefit analysis to determine the most cost effective geosynthetic materials and provided support to TAK for procuring the materials. Geosyntec also provided continuous onsite construction oversight during the second test plot.
TAK received a comprehensive design for the MWS cover system that utilized on-site materials and equipment whenever possible to reduce costs and optimize construction schedules. Geosyntec's expertise in the design and installation of geosynthetic cover systems along with our thorough knowledge of the mining industry resulted in a successfully managed project in a challenging remote arctic site location. The project team delivered a valuable solution to the client.