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bruce lake

Read today the news that the Brucejack Mine have been given an environmental assessment certificate by the British Columbia Ministry of the Environment.   The regulators say construction can begin once they are sure that discharges from water treatment plants will not harm the Unuk River.  Some of the tailings will go back underground; some will go to Brucejack Lake which is apparently “fishless.”  Most of the waste rock will go to the lake.

I read the following in the June 2014 Feasibility Study and Technical Report Update for Pretium Resource Inc. by Tetra Tech.

Approximately 3.5 Mt of waste rock and 8.7 Mt of tailings are anticipated to be deposited in Brucejack Lake over the projected 18-year mine life. Stringent discharge criteria (based on the Metal Mining Effluent Regulations (MMER)) state that the total suspended solids (TSS) concentrations in the outflow at Brucejack Creek must be less than 15 mg/L.

The tailings deposition system has been developed to minimize the concentration of fine suspended solids in the outflow to Brucejack Creek by discharging near the bottom of the lake (at 80 m depth) and under the accumulations of tailings solids.

On the other hand, waste rock with a wide range of particle sizes is to be deposited in the lake by surface dumping from causeways raising the possibility that fine granular material will be introduced to the surface layer of the lake and to the outflow.

Hydrodynamic modelling of Brucejack Lake was carried out by Lorax (2013) to examine the likelihood of the migration of tailings solids into lake surface waters. The results indicated that the potential for elevated TSS levels in surface waters was unlikely if the minimum particle diameter was greater than or equal to 5 µm.

However, it will be necessary to control the TSS concentrations at the outlet of Brucejack Lake to meet the MMER regulations. The current design basis for control of suspended solids includes the following:

  •  install one or more lines of turbidity curtains at the outlet of the lake to contain suspended solids
  • install a flow monitoring weir across Brucejack Creek downstream from the lake outlet to facilitate monitoring.

An allowance for site investigation and design of the outflow monitoring weir has been included in the capital cost estimate. As a contingency to the use of turbidity curtains, an outlet control structure was designed to allow storage and release of lake water in a controlled manner.

Review of the storage capacity versus lake level elevation for the outlet control structure indicates that flow from the lake could be stopped for a period ranging from several days (e.g. during freshet) to several tens of days (e.g. during the summer and early fall) depending upon runoff conditions in the lake catchment area.

If you have an idle weekend, you can spend plenty of time reading additional documents at this link.   For me it is off to the MET opera, the Tales of Hoffman, so I will say no more than this seems good news:  a BC mine advancing with a rational tailings and waste rock disposal system.  Good for them.  I hope they succeed.

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If you are interested in the use of geosynthetics in mining, or seek to use geosynthetics in mining, or need as a consultant to provide your client with advice on geosynthetics in mining, or you are a manufacturer or supplier of geosynthetics to mines, then you should join us March 10 to 12th on the upcoming EduMine webcast. (more…)

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Happy New Year

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The sun is shining on the patio where we sit looking across the bay from Cadiz.  Here is a picture of a wooden ship in the local harbor, Sherry Bay.   All considered it has been a good year.  So to all let me wish a Happy 2015.

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2014 in review

The WordPress.com stats helper monkeys prepared a 2014 annual report for this blog.

Here's an excerpt:

The Louvre Museum has 8.5 million visitors per year. This blog was viewed about 220,000 times in 2014. If it were an exhibit at the Louvre Museum, it would take about 9 days for that many people to see it.

Click here to see the complete report.

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Mallorca is an island to the east of Spain.  I am now at a Marriott resort in a fancy villa.  Today we swam in the biggest heated pool I have ever seen.  Then we went grocery shopping in Llucmajor in a grocery store full of hamon, turron, and cheap Spanish wine. We flew here from Jerez in southwestern Spain after a week in Rota in a house overlooking a perfect beach.  Back there at the end of the week for two more weeks of time with my son and his family. Took a tour around the naval base and saw the destroyer my son works on: the USS Ross.  Impressive in the mists of a cool morning.  They are in port to be refurbished. Also took a nativity trip around the city to see the many nativity scenes that are a staple of the Christmas decorations.  Here are a few photos of where we are and have been. (more…)

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Sometimes a blog is just that: a biographical log, a diary, a record of daily thoughts & doings. So here are a few random thoughts & doings from this weekend. No Mt Polley except yesterday’s ruminations on the inadequacy of bonds for mine closure.  Some good comments.  See previous posting. The weekend started with a lover: the blond hairs turned golden in the rays of the setting sun. And the rest is unrecordable. (more…)

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The numbers just do not add up. As I read the many sites on the web, I learn that British Columbia has about thirty operating mines. The BC government has about $172 million in closure bonds. Say about five or six million a mine. That seems grossly inadequate to me. I have just finished estimating closure of one mine and it came to nearly $60 million. Does this mean BC should have $1.7 billion in closure bonds? Here are some observations from various websites that may help you ponder this issue. (more…)

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