subscribe to ENR magazine subscribe
contact us
careers industry jobs
events events
Mcgraw Hill Construction
ENR Logo
& receive immediate web access

Mount Polley Dam Failure Raises Bar for Pebble Mine Backers

Text size: A A
[ Page 1 of 2 ]
Proposed mine shares watershed with world's largest sockeye salmon spawning ground.
----- Advertising -----

The Mount Polley mine spill, in which a tailings pond failure dumped more than 8 million gallons of water, silt and sand into waterways, is likely to provide further ammunition for opponents of the Pebble Mine, an even larger copper and gold project planned in Alaska.

Located about 200 miles southwest of Anchorage, the Pebble Mine would be an open-pit mine owned by Northern Dynasty Minerals Ltd., Vancouver, British Columbia.

Northern has not filed specific plans with the U.S. Environmental Protection Agency, but the agency’s analysis and a recent determination are based on plans Northern filed with the U.S. Securities and Exchange Commission. Those plans are based on mines producing between 2 billion and 6.5 billion tons per year. The EPA analyzed both sizes as well as a smaller 250-million-ton mine.

“The extraction, storage, treatment and transportation activities associated with building, operating and maintaining one of the largest mines ever built would pose significant risks to the unparalleled ecosystem that produces one of the greatest wild salmon fisheries in the world,” the EPA said in a report issued July 18.

“In simple terms, the infrastructure necessary to mine the Pebble deposit jeopardizes the long-term health and sustainability of the Bristol Bay ecosystem.”

The EPA would drastically restrict discharge of dredged or fill material from the mine. It is taking public comment until Sept. 19 on the report.

The Pebble Mine “is likely to involve excavation of the largest open pit ever constructed in North America, covering up to 6.9 sq miles and reaching a depth at much as .77 miles” or almost as deep as the Grand Canyon, the EPA report says.

Tailings ponds are another issue.

“Disposal of resulting waste material would require construction of up to three mine tailings impoundments” covering 18.8 sq miles and waste rock piles covering up to 8.7 sq miles, it says.

The volume of mine tailings and waste rock produced from a 2-billion-ton mine would be enough to fill a professional football stadium more than 880 times, volume that would grow to more than 3,900 stadiums for a 6.5-billion-ton mine, the EPA says.

The mine pit, tailings ponds and rock piles “would cover an area larger than Manhattan,” it says.


[ Page 1 of 2 ]
----- Advertising -----
  Blogs: ENR Staff   Blogs: Other Voices  
Critical Path: ENR's editors and bloggers deliver their insights, opinions, cool-headed analysis and hot-headed rantings
Project Leads/Pulse

Gives readers a glimpse of who is planning and constructing some of the largest projects throughout the U.S. Much information for pulse is derived from McGraw-Hill Construction Dodge.

For more information on a project in Pulse that has a DR#, or for general information on Dodge products and services, please visit our Website at

Information is provided on construction projects in following stages in each issue of ENR: Planning, Contracts/Bids/Proposals and Bid/Proposal Dates.

View all Project Leads/Pulse »

 Reader Comments:

Sign in to Comment

To write a comment about this story, please sign in. If this is your first time commenting on this site, you will be required to fill out a brief registration form. Your public username will be the beginning of the email address that you enter into the form (everything before the @ symbol). Other than that, none of the information that you enter will be publically displayed.

We welcome comments from all points of view. Off-topic or abusive comments, however, will be removed at the editors’ discretion.