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Updated: Wed, 06 Aug 2014 09:20:18 GMT | By CBC News, cbc.ca

Mount Polley mine tailings pond breach followed years of government warnings

Aerial footage shows the debris and milky blue-green tailings pond water that washed into nearby waterways after the Mount Polley Mine tailings pond breached Monday, Aug. 4, 2014. Cariboo Regional District/Facebook

Aerial footage shows the debris and milky blue-green tailings pond water that washed into nearby waterways after the Mount Polley Mine tailings pond breached Monday, Aug. 4, 2014. Cariboo Regional District/Facebook

The B.C. Ministry of Environment says it warned Imperial Metals about the Mount Polley mine tailings pond levels repeatedly before this week's devastating breach.

The breach of the tailings pond dam at the copper and gold mine near Likely, B.C., released 10 billion litres of water and 4.5 million cubic metres of metals-laden fine sand, contaminating several lakes, creeks and rivers in the Cariboo region on Monday.

- MORE | Mount Polley Mine tailings water 'very close' to drinking quality, company says

- IN DEPTH | Tailings ponds: What's in them and what risks do they pose?

- RAW VIDEO | View from a helicopter over the tailings breach zone

- PHOTOS | 'The devastation up the lake is unbelievable'

In an email to CBC News, a Ministry of Environment spokesperson said it gave the firm its latest of five warnings in May, this time for exceeding the permitted height of wastewater within the tailings pond.

The ministry said the company has applied for two permit amendments in recent years to allow the mine to discharge an increasing amount of wastewater.

The first of these, in 2009, prompted an independent report. The second, submitted this summer, was under consideration by the ministry at the time of the tailings pond breach.

Brian Olding, the environmental consultant who carried out the 2009 assessment for the company and local First Nations groups, says the pond levels were already getting too high five years ago.

"It means the water is rising so you have to build the walls of the tailings lagoon higher as you go," Olding said.

When his report was published in 2011, the tailings pond was accumulating water so quickly that it would have needed to discharge about 1.4 million cubic metres of water per year to keep its levels stable.

"A sustainable means of discharging excess water is required because dam building cannot continue indefinitely," the report said in June 2011.

The report also criticized the company for not having a contingency plan in case of a tailings pond failure. It wasn't clear Tuesday if such a plan had been developed between the report's completion and the dam breach.

Olding said in an interview with The Canadian Press that no analysis of the dam's structural integrity was done as part of the review.

"I requested a structural engineering company be involved, and that was nixed. They did not want to deal with that problem at that time."

"I think the permit [amendment] should have been attained sooner ... A wastewater treatment process should have been put in," Olding told CBC News. 

In 2012, the mine was granted the permit amendment it had requested, allowing the company to discharge 1.4 million cubic metres of wastewater per year into nearby Hazeltine Creek.

- Scroll down to read Olding's report on the Mount Polley mine

14 inspections, 5 warnings

The B.C. Ministry of Environment says it has conducted 14 inspections of the Mount Polley mine since that permit amendment was granted.

In August 2012, the ministry found the mine failed to report the excessive height of wastewater for the perimeter pond. The perimeter pond overflowed, releasing approximately 150 cubic metres of wastewater over 13 hours to ground.

On two occasions the firm failed to submit monitoring data for one of its groundwater monitoring wells, the ministry found.

Then in April of this year, the ministry found the mine experienced high flows due to spring freshet, which blocked the pump system and resulted in an overflow of wastewater. The ministry issued an advisory to the company for bypassing of authorized treatment works. The wastewater did not reach the creek and was directed to another pit.

Finally, three months ago the ministry warned Imperial Metals yet again, after the height of wastewater in the tailings pond exceeded authorized levels.

According to the ministry, the wastewater level eventually returned to normal one month later.

In summer 2014, the firm applied to amend its permit again, this time to allow a discharge of 3 million cubic metres of treated wastewater or ditch water into Polley Lake, which overflows into Hazeltine Creek.

Tailings pond water exceeded guidelines

According to the B.C. Ministry of Environment, Environmental Protection Division staff reviewed data submitted by Mount Polley mine about the liquid found in the tailings pond this month.

Concentrations of various metals and compounds in mine wastewater in the province are regulated under a generic set of guidelines known as the British Columbia Water Quality Guidelines. However, because complex factors influence how substances will react in the environment, companies are allowed to develop site specific standards in many cases. 

Upon review Environment Ministry staff found concentrations of some substances exceeded the preferred levels at the Mount Polley site as follows:

- Selenium – exceeded drinking water guideline of 10 ug/L by a factor of 2.8 times.

- Sulphate – no current problem, but frequently exceeded drinking water guideline of 500 mg/L over the last several years.

- Molybdenum – recent molybdenum concentrations in the tailings pond water exceeded livestock watering and irrigation guidelines of 0.05 mg/L.

- Organic carbon concentrations – exceeded the 4 mg/L guidelines for chlorination.

In addition, staff found the concentration of several other substances in the tailings pond water exceeded aquatic life guidelines, such as nitrate, cadmium, copper, iron and selenium, albeit sporadically, in the last few years.

Final Report - Mount Polley Technical Assessment Review Jun 21 2011

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