Chief Inspector of Mines' Investigation Report on Mount Polley

The Report

Immediately following the August 4, 2014 breach of the tailings storage facility at the Mount Polley Mine, the Chief Inspector of Mines launched an investigation into the incident. This report outlines the findings of the investigation that was conducted by a team of investigators who performed a comprehensive, objective and independent investigation into the incident.

The investigation report, which can be viewed and downloaded below, contains the process and findings of the investigation and the 19 recommendations made by the Chief Inspector of Mines.


Supporting Information


The Chief Inspector of Mines investigation team reviewed over 100,000 pages of documents in the course of their investigation. The documents and other files cited in the Investigation Report are available here in Portable Document Format (PDF), and are organized first by type and then by their 4-digit document identifier.

The following is a list of acronyms and abbreviations used in the References.

Acronyms and Abbreviations

Acronym Definition
AMEC Amec Earth & Environmental Division of AMEC Americas Ltd. (presently operating as Amec Foster Wheeler)
BGC BGC Engineering Ltd.
CIM Chief Inspector of Mines
KCB Klohn Crippen Berger Ltd.
KP Knight Piésold Ltd.
MEM Ministry of Energy and Mines
MOE Ministry of Environment
MPMC Mount Polley Mining Corporation
OMS Operation, Maintenance and Surveillance Manual
TSF Tailings Storage Facility

Files by type (PDFs)

  1. Work Products
  2. Ministry of Energy, Mines and Petroleum Resources Inspection Reports
  3. Permits
  4. Mount Polley Mine Policies and Procedures
  5. Correspondence
  6. Notes and Other Files

Work Products

Document ID Title Author Date
DOC0017 File Management Report (736KB) William Ard September 14, 2014
DOC0024 Report of Geotechnical Inspector, Inspection No. 47976 - order issued to MPMC (149KB) Al Hoffman December 5, 2014
DOC0026 Report of Inspector of Mines No. 48756 - order discussing ground conditions on the mine (35KB) John Cox December 4, 2014
DOC0027 Inspection Order to Dale Reimer, Mine Manager, MPMC - regarding the Mine Emergency Response Plan (420KB) Cheryl Pocklington September 11, 2014
DOC0033 Memorandum to Dale Reimer, Mine Manager, MPMC - regarding the need to protect the scene of the breach for the purposes of the Chief Inspector's investigation (32KB) Steve Rothman August 21, 2014
DOC0178 Report of Inspector of Mines, Inspection No. 48856 - order regarding dust exposure in the crusher (545KB) Al Hoffman December 10, 2014
DOC0237 Order Stop Work McLean - order to stop excavator from removing rock from the toe of the dam (22KB) Greg McLean September 7, 2014
DOC0400 TSF 2011 Geotechnical Site Investigation (82.6MB) AMEC March 28, 2012
DOC0412 Report on 1999 construction (7.7MB) KP August 30, 2000
DOC0417 MP10035 - Mount Polley Mine tailing facility optimization potential: Follow up from the Dam Safety Review (720KB) AMEC February 23, 2007
DOC0423 MP00056 - Request sent by MEM for independent review (59KB) George Headley September 5, 1995
DOC0426 MP00066 - Summary of telephone call between George Headley and Ken Brouwer (36KB) George Headley July 23, 1996
DOC0430 MP00070 - Note to File, File No. 14745-40/MTPO/01 (43KB) George Headley August 2, 1996
DOC0458 MP00094 - Letter to Brian Kynoch, MPMC - regarding permission to impound water from Mount Polley tailings dam (38KB) George Headley March 14, 1997
DOC0462 MP00046 - TSF Operation, Maintenance and Surveillance Manual 2013 (7.7MB) MPMC July 1, 2013
DOC0464 MP00052 - MPMC responses to review comments by Diane Howe and Chris Carr of November 1, 2011 Mine Permit Amendment application (436KB) MPMC January 25, 2011
DOC0475 MP00102 - Internal government email discussing scope of Fred Matich review work (41KB) George Headley June 29, 1998
DOC0485 MP00123 - Internal government email requesting reclamation inspector Brian McBride follow up with Mount Polley on the importance of moving the leaking tailings pipe (106KB) Chris Carr May 1, 2001
DOC0493 MP00130 - MEM acknowledgement of receipt of 2002 Annual Inspection report (36KB) Chris Carr June 26, 2003
DOC0566 MP00001 - TSF Design Report (7.9MB) KP May 25, 1995
DOC0567 MP00002 - TSF Design Report Appendices (12.1MB) KP May 26, 1995
DOC0568 MP00003 - TSF Site Inspection Manual (1.52MB) KP May 26, 1995
DOC0570 MP00005 - Response to Review Comments on Tailings Embankment Design (4.97MB) KP January 26, 1996
DOC0571 MP00007 - TSF Construction Drawings (15.8MB) KP May 30, 1997
DOC0572 MP00008 - Report on on-going construction requirements (40.6MB) KP December 2, 1997
DOC0573 MP00009 - Operation, Maintenance and Surveillance Manual for Stage 1B embankment (7.91MB) KP November 24, 1997
DOC0574 MP00011 - 1998 Annual Inspection Report of the tailings storage facility (39.2MB) KP June 26, 1998
DOC0575 MP00012 - Report on 1998 construction and the annual inspection (65.3MB) KP June 16, 1999
DOC0576 MP00013 - Evaluation of cycloned tailings for embankment construction (23MB) KP June 16, 1999
DOC0577 MP00014 - Report on cycloned sand construction of Stage 3 and ongoing stages of the tailings storage facility (45.8MB) KP December 13, 1999
DOC0582 MP00021 - Addendum to December 13, 1999 report on cycloned sand construction of Stage 3 (25MB) KP May 11, 2000
DOC0584 MP00026 - Design of the Tailings Storage Facility to Ultimate Elevation (87.6MB) KP May 14, 2005
DOC0585 MP00027 - Stage 5 design of the TSF (17.9MB) KP June 12, 2006
DOC0586 MP00031 - Report on Stage 4 construction (88.6MB) KP March 13, 2007
DOC0587 MP00032 - Stage 6 design of the TSF (21.5MB) KP June 18, 2007
DOC0588 MP00033 - Report on Stage 5 construction (17.4MB) KP March 27, 2008
DOC0589 MP00034 - Report on Stage 6A construction (17.7MB) KP July 10, 2009
DOC0590 MP00035 - Report on 2008 Annual Inspection (58.9MB) KP February 25, 2009
DOC0591 MP00036 - Report on Stage 6B construction (26.7MB) KP January 25, 2011
DOC0592 MP00037 - Report on 2010 Annual Inspection (6MB) KP January 25, 2011
DOC0602 MP00060 - Letter to George Headley, MEM (5.1MB) Ken Embree October 6, 1995
DOC0608 MP00072 - Report on Stage 3 construction (20.5MB) KP October 19, 2001
DOC0623 MP00116 - Meeting minutes regarding Stage 3 cyclone sand construction (353KB) KP February 13, 2000
DOC0625 Letter to Chris Carr, MEM (186KB) KP April 14, 2005
DOC0629 MP00225 - Letter to Chris Carr, MEM in response to questions posed about Stage 6 design (740KB) KP December 19, 2007
DOC0639 MP00017 - External review report focused on the geotechnical characterization and drainage measures within and below the main embankment (22.7MB) MAJM Corporation March 1, 1997
DOC0641 MP00039 - Stage 7, 2011 Construction Monitoring Manual (10.5MB) AMEC April 20, 2011
DOC0642 MP00040 - Stage 8, 2012 Construction Monitoring Manual (3.2MB) AMEC March 30, 2012
DOC0643 MP00041 - 2011 Construction As-Built and Annual Review (7.3MB) AMEC March 30, 2012
DOC0644 MP00042 - Stage 8A TSF construction drawings and stability analyses for embankment raise to el. 965 m (7.2MB) AMEC September 12, 2012
DOC0645 MP00043 - 2012 Annual Dam Safety Inspection (70.1MB) BGC April 8, 2013
DOC0646 MP00044 - Stage 9, 2013 As-Built and Annual Review Report (40.7MB) AMEC March 12, 2014
DOC0647 MP00045 - Stage 9, 2013 Construction Monitoring Manual (11.3MB) AMEC April 11, 2013
DOC0651 MP00061 - Communication to MEM regarding proposed Mount Polley tailings dam (137KB) C.O. Brawner October 13, 1995
DOC0657 MP00104 - Final Report: Dam Safety Review (52.1MB) AMEC December 1, 2006
DOC0658 MP00109 - Letter on Mount Polley tailings dam cyclone sand proposal (128KB) George Headley January 23, 2000
DOC0659 MP00110 - Letter requesting that Chuck Brawner review the proposed cycloned sand design (127KB) Tim Eaton February 4, 2000
DOC0668 MP00208 - Stage 10 design report (5.4MB) BGC July 25, 2014
DOC0672 MP00217 - Stage 8/8A 2012 As-Built Report (26.8MB) AMEC March 27, 2013
DOC0872 Report on 1995 geotechnical Investigations for mill Site and TSF (12.3MB) KP March 14, 1995
DOC1532 Root Cause Analysis Tool - Event and Causal Factor Tree (3.4MB) MEM November 16, 2015
DOC1534 Recommendations Summary Chart (92KB) MEM November 16, 2015

Ministry of Energy, Mines and Low Carbon Innovation Inspection Reports

Document ID Title Author Date
DOC0031 Report of Inspector of Mines: Geotechnical (58KB) Michael Cullen December 4, 2014
DOC0419 MP00142 - Response to geotechnical inspection conducted on October 13, 2005 (233KB) MPMC February 16, 2006
DOC0420 MP00149 - Response to geotechnical inspection conducted on August 30, 2006 (71KB) MPMC October 5, 2006
DOC0422 MP00154 - Geotechnical Inspection Report (65KB) George Headley September 30, 1995
DOC0427 MP00156 - Geotechnical Inspection Report (41KB) George Headley October 11, 1995
DOC0431 MP00158 - Geotechnical Inspection Report (59KB) George Headley July 9, 1996
DOC0432 MP00159 - Geotechnical Inspection Report (78KB) George Headley August 26, 1996
DOC0434 MP00160 - Geotechnical Inspection Report (54KB) George Headley September 27, 1996
DOC0435 MP00161 - Geotechnical Inspection Report (54KB) George Headley June 5, 1997
DOC0438 Geotechnical Inspection Report (78KB) George Headley June 4, 1998
DOC0439 MP00166 - Geotechnical Inspection Report (61KB) George Headley July 12, 1999
DOC0441 MP00169 - Geotechnical Inspection No. 24197 (4.2MB) Michael Cullen September 24, 2012
DOC0442 MP00170 - Geotechnical Inspection Report (78KB) Chris Carr May 3, 2001
DOC0444 MP00172 - Geotechnical Inspection Report No. 11922 (4.8MB) Chris Carr February 17, 2005
DOC0446 MP00174 - Geotechnical Inspection Report No. 12476 (123KB) Nick Rose October 13, 2005
DOC0447 MP00175 - Geotechnical Inspection Report No. 13437 (98KB) Nick Rose September 22, 2006
DOC0448 MP00177 - Geotechnical Inspection Report No. 14355 (93KB) Nick Rose October 2, 2007
DOC0450 MP00181 - Geotechnical Inspection Report No. 15354 (155KB) Derek Apel July 7, 2008
DOC0451 MP00182 - Geotechnical Inspection Report (4.2MB) Michael Cullen September 27, 2013
DOC0541 MP00218 - Response to May 3, 2001 Inspection Report conducted by Chris Carr (187KB) MPMC May 21, 2001
DOC1531 Geotechnical Inspection Report No. 16760 (199KB) John Cox September 1, 2009
DOC1533 Geotechnical Inspection Report No. 6448 (40KB) Brian McBride June 6, 2002


Document ID Title Author Date
DOC0282 Mines Act Permit M-200, amendment approving TSF breach repair design for 2015 spring freshet (391KB) Al Hoffman December 17, 2014
DOC1386 Amended Ministry of Environment Permit No. 11678 (304KB) MOE November 7, 2012
DOC1387 Decision Record for Permit No. 11678 amendment (419KB) MOE November 7, 2012
DOC1388 Ministry of Environment assessment of permit amendment (646KB) MOE October 26, 2012

Mount Polley Mine Policies and Procedures

Document ID Title Author Date
DOC1536 TSF Emergency Levels and Procedures (30KB) MPMC (no date)
DOC1537 Mill Operators Tailings Check Procedure (20KB) MPMC January 1, 2007


Document ID Title Author Date
DOC0296 Interview Request Letter sent to Stephen Rice, representing MPMC (38KB) Al Hoffman September 24, 2014
DOC0297 Interview Request Letter sent to Daryl Dufault, BGC Engineering (37KB) Al Hoffman September 24, 2014
DOC0298 Interview Request Letter sent to Ken Brouwer, Knight Piésold (56KB) Al Hoffman September 24, 2014
DOC0368 Chief Inspector's Orders in follow-up to site inspections of August 4-8, 2014 (75KB) Al Hoffman August 11, 2014
DOC0389 MP00006 - Letter to MEM regarding the foundation prep below the main embankment (4.6MB) C.O. Brawner October 23, 1995
DOC0428 MP00069 - Letter to Brian Kynoch regarding the permit to construct the Stage 1B starter dam to 934 m (99KB) George Headley July 30, 1996
DOC0443 MP00171 - Email regarding Geotechnical Site Visit on April 12, 2012 (60KB) George Warnock April 12, 2012
DOC0490 MP00128 - Letter to MPMC including a reminder of an overdue Annual Dam Safety Inspection (67KB) Chris Carr April 22, 2002
DOC0494 MP00137 - Email discussing review of the KP report "Design of the TSF to Ultimate Elevation" (20KB) Chris Carr April 7, 2005
DOC0510 MP00179 - Letter to MPMC stating completion of review of TSF 2007 Annual Inspection (36KB) Chris Carr April 22, 2008
DOC0514 MP00188 - Internal MEM correspondence regarding dam overtopping incident (95KB) Heather Narynski May 27, 2014
DOC0520 MP00187 - Email regarding MEM comments on Stage 9 design application (116KB) MPMC July 31, 2013
DOC0521 MP00193 - May 27, 2014 freeboard incident and follow-up (213KB) Michael Cullen June 3, 2014
DOC0523 MP00195 - Mount Polley update on reestablishing freeboard after May 27, 2014 incident (265KB) MPMC June 6, 2014
DOC0532 MP00204 - May 27, 2014 freeboard incident and follow-up (142KB) MPMC July 18, 2014
DOC0533 MP00205 - May 27, 2014 freeboard incident and follow-up (107KB) Heather Narynski July 8, 2014
DOC0548 MP00232 - Correspondence between MEM and MPMC regarding submission of the updated 2012 OMS manual and updated site water balance (49KB) Luke Moger May 8, 2013
DOC0667 MP00192 - MPMC geotechnical incident memo for May 30; AMEC account of freeboard incident with photos (2.7MB) Dmitri Ostritchenko June 2, 2014
DOC0710 Letter to Harvey McLeod regarding MPMC information request (399KB) KP December 17, 2014
DOC0928 BGC Engineering Memo: TSF Stability Modeling (2.1MB) Daryl Dufault October 3, 2013
DOC1240 Email to MPMC regarding water discharge permits (553KB) Art Frye February 18, 2004
DOC1416 Response to MOE comments, titled "Identification of Priority Parameters at the Mount Polley Mine and Development of Site-Specific Water Quality Objectives" (260KB) Minnow Environmental November 7, 2006

Notes and Other Files

Document ID Title Author Date
DOC0003 Mine Emergency Primary Form, Emergency Management BC report forms and accompanying on-call inspector notes (1.2MB) Jerrold Jewsbury August 1, 2014
DOC0010 Terms of Reference for the Mount Polley Mine Breach Chief Inspector's Investigation (528KB) Keith Elwood September 24, 2014
DOC0392 Dam breach incident notes (134KB) Chris Carr August 4, 2014
DOC1482 May 24, 2014 freeboard incident notes (89KB) Heather Narynski May 11, 2015