Diavik mine owner appeals to N.W.T. minister for help in regulatory dispute

The company operating the Diavik diamond mine says the denial of a change to its water licence could have an "immediate and materially-adverse impact" on the mine.

Dike construction around future pit 'challenging' under current licence conditions: company

Rio Tinto's Diavik diamond mine is located about 300 kilometres northeast of Yellowknife, partly on Lac de Gras. (2015 DDMI Sustainable Development Report )

The company operating the Diavik diamond mine says the denial of a change to its water licence could have an "immediate and materially-adverse impact" on the mine. 

Now the company is appealing to the N.W.T.'s Minister of Environment and Natural Resources for a chance to air its concerns. 

Diavik Diamond Mines Inc. (DDMI), the Rio Tinto subsidiary that operates Diavik, is building a new, $456-million pit inside Lac de Gras, located about 300 kilometres northeast of Yellowknife. The pit, called A21, is expected to help the mine remain open until at least 2024.

The new A21 open pit is located on the southern end of the Diavik site. (DDMI 2015 Sustainable Development Report )

Last summer, during construction of the dike that will enclose the pit, the malfunction of a silt curtain caused the level of total suspended solids (TSS) in one area of the lake to go over the regulated limit of 25 milligrams per litre.

That's the limit that remains protective of all aquatic life, as established by the Canadian Council of Ministers of the Environment. 

Inspector threatens construction shutdown 

The exceedance last summer prompted a stern warning from an inspector with the N.W.T. government.

"Should any further exceedances occur the inspector will have no alternative but to terminate the source of the high TSS," Tracey Covey, an inspector with the N.W.T. Department of Lands, wrote to DDMI. 

"This will be achieved through termination of dredging and other A21 related in-water construction activities."

At issue is how DDMI's compliance with water quality guidelines for Lac de Gras should be measured. (DDMI 2015 Sustainable Development Report )

DDMI says TSS concentrations during dike construction are affected by variables outside the company's control, such as wind speed, wind direction and lake current.   

Citing a concern that the upcoming 2016 dike construction season will be "more challenging" than last year's when it comes to managing TSS, DDMI is asking that the TSS limit be relaxed.

In essence, the company wants the level of TSS to be measured using a 30-day average, instead of going day by day. 

Board sticks with current limit 

Last week, however, in a recommendation to N.W.T. Environment Minister Wally Schumann, the Tlicho region's Wek'eezhii Land and Water Board said the existing daily limit of 25 milligrams per litre should remain in place.

DDMI has now written to Schumann directly.

Citing "serious concerns" with the board's decision — which needs to be approved by the minister — Louis Béland, a lawyer for DDMI, wrote, "We respectfully request that you defer your decision to approve the amendment or not until we have had a chance to communicate in more detail why the proposed amendment is so problematic and to investigate the options available to us."

"There is no urgency that would justify rendering an immediate decision," Béland added. 

No one from DDMI was available for an interview Wednesday. 

Ryan Fequet, the executive director of the Wek'eezhii Land and Water Board, says DDMI has had the opportunity to weigh in on the issue

"The board's process includes a series of opportunities for parties to submit evidence (comments, concerns, support for, recommendations, etc.) on the proposed amendment," he wrote via email. "The board's recommendation is now with the minister for his consideration."

DDMI's construction schedule calls for the dike around A21 to be enclosed this year and for production from the A21 open pit to begin in 2018.

Construction of the dike employed 97 people last year. A quarter of those people were aboriginal and from the North.