According to Mount Polley Mine Corp. colour changes seen in Quesnel Lake are due to the sediment plume that resulted from the Aug. 4 tailings breach.
“When the sediment plume rises up there’s higher total suspended solids in the water than normal,” said Steve Robertson, MPMC vice-president of corporate affairs. “It has the same effect that you would see in a glacial lake.”
And when the sun angle hits it, it diffuses and sends out a green colour and is basically a light diffusion from the clay particles that are suspended in the water, he explained.
While that is a plausible explanation for the colour change, concerns continue and the fact the particles are in there doesn’t make it any better, said Ellen Petticrew, geography professor who works at the UNBC Quesnel Lake Research Centre.
“We are still concerned about the quality of those sediments and how they are moving in Quesnel Lake and Quesnel River and effecting the quality of the water,” Petticrew told the Weekend Advisor Thursday.
Petticrew and other UNBC faculty, staff and students are actively involved in research to understand the immediate and longer term environmental and ecological implications of the mine failure.
They are collecting water, sediment, and biological samples from the Quesnel watershed and looking at the movement of water and sediment plumes in Quesnel Lake. Working with several other organizations, including universities, federal and provincial governments, research institutes, and First Nations, they will present preliminary findings at the annual QRRC open house on Saturday Oct. 4.
Robertson confirmed there is still a lot of wood debris in the lake the company hopes to have removed by the end of October.
“It’s a big job,” Robertson said. “There’s a lot of material to move.”
Crews are presently focusing on the Hazeltine Creek area where wood is hung up on the delta.
It will take a lot of work to get it off the delta, untangle it, bag it and tow it to spot where it can be removed from Quesnel Lake.
Some of the wood has gone for saw logs, some for pulp and there’s a lot of hog fuel that will be put through a grinder.
The company is also waiting for approval from the Ministry of Environment to proceed with work going in the lower Hazeltine Creek, but they are re-establishing some of the roads and going ahead with putting creek crossings back in.
“We had bridges over the creek at Gavin Lake Road and the Ditch Road and we’re re-decking the crossing over [Ednie] Creek because we might want to haul material in that way,” Robertson said. “That bridge wasn’t affected by the breach.”
The main dike construction at the site has been completed, but the company is still doing work in the area to build ramps down into areas where sump-pumps will be installed upstream of the dike.
Robertson said there has been some mining on site in the pit to mine materials for building the dike, but the mill is not operating.
“There is a magnetite plant on site that has been trucking out stockpiled magnetite, but they aren’t operating,” Robertson said. “Our staff is working on the cleanup efforts.”
Polley Lake has been pumped down over 60 centimetres and the investigations are starting to get underway into what happened, he confirmed.
Robertson said public meetings are now scheduled every two weeks in Likely, with the next meeting taking place Thursday, Sept. 25.