Rio Tinto drops request to change water quality rules at Diavik mine
Company was asking board to relax the limit for total suspended solids in Lac de Gras
Rio Tinto is no longer asking for more flexible water quality rules at the N.W.T.'s Diavik diamond mine.
The company had asked the Wek'eezhii Land and Water Board to relax the limit for total suspended solids in Lac de Gras.
- Critics say Rio Tinto was wrong to lobby N.W.T. minister on Diavik water issue
- Water quality issue halts $450M Diavik mine expansion project for 3 days
Rio Tinto is building a dike in the lake to help it develop the new A21 open pit at Diavik, and worried that, without tweaking of the limit, construction activities would put the company out of compliance with its water licence, threatening the future of the $456-million pit.
In what some groups saw as an inappropriate case of lobbying, the company reached out to the minister of environment, Wally Schumann, after the board recommended even more strict rules than the ones in place now.
Schumann shot down that recommendation, turning back the clock on the process.
On Wednesday, the board said the earliest it could issue a new recommendation to Schumann is mid-September.
But in a letter to the board Wednesday, Rio Tinto said that won't cut it, because that's about when the dike construction season is going to wrap up.
Rio Tinto said it was dropping its request "as there is no reasonable expectation of benefit to A21 dike construction."
The company declined to comment further, even as its decision raises the question of whether the rest of the dike construction season will unroll without more delays.
Dike construction
Earlier in the week, Gord Macdonald of Diavik Diamond Mines Inc., the Rio Tinto subsidiary that operates Diavik, noted that August and September tend to be windier than July.
That's of concern because high winds have previously caused the turbidity barrier inside the lake to malfunction, causing dirt from the construction area to migrate and cloud other parts of the lake.
"There are headwinds against us, no pun intended," said Macdonald.
When the curtain malfunctioned last year, causing a spike in TSS levels, an inspector with the territorial government threatened to shut down activity at the site if it happened again.
Levels did spike again last month, with Rio Tinto voluntarily pausing construction for three days.
The company's schedule calls for the dike to be enclosed by the end of September.