taproot investigative report - 23 april 2007€¦ · the october incident taproot® report...

Cigar Lake Project

Mine Flood Incident Cigar Lake Uranium Mine

October 22, 2006

Cameco’s Responses to the TapRoot® Investigation Report

& TapRoot® Investigation Report

April, 2007

May 1, 2007

Cameco’s Responses to the Corrective Action Recommendations (CAR’s)

Developed in the April, 2007 TapRoot® Report

ATTACHMENT 1

Attachment 1

Response to the Corrective Action Recommendations -

TapRooT® Investigation Report

Mine Flood Incident - Cigar Lake Uranium Mine - October 22, 2006 (April 2007)

Glossary of Terms

CIRS - Cameco Incident Reporting System - a system designed to support the common non-conformance and incident tracking needs for all of the management programs, which fall under Cameco’s SHEQ program. DRE – Drift East – drifts with this designation are in an east/west orientation on the mine plan Engineered Mine Plan – the driving layouts issued to the main mining contractor on site (MTM) by site mine engineering personnel for construction. EPRP - Emergency Preparedness and Response Program - one of the program elements that supports the SHEQ program. MFLM – Mining Facility Licensing Manual – a document referenced specifically in support of the CNSC license, it describes the licensed activities identified in the license. MFPM – Mining Facility Program Manual – a document referenced specifically in support of the license, it describes how the activities of the license will be managed and lists the specific site programs that will be used to dictate this. MRT – Mine Rescue Team MTM – Mudjatik Thyssen Mining - the main mining contractor at the Cigar Lake site. QMP - Quality Management Program – represents one of the program elements that support the SHEQ program. QMS- quality management system - is a more general term that refers to how work processes are managed. For Cameco, this system is institutionalized through the QMP. SAT - Systematic Approach to Training – a specific process mandated by the CNSC, for the development of training, managing its delivery and maintenance of the personnel qualifications at Cameco’s operations.

Page 1 of 42 1

ATTACHMENT 1

SHEQ program – Safety, Health, Environment and Quality management program - each category (Safety, Health, Environment and Quality) has its own sub-program that is structured on the processes of the Quality Management Program. SME – Subject Matter Expert Target sheets – a means by which operational expectations are communicated to employees responsible for the implementation of procedures, work instructions or the execution of plans, where specific variances not covered by these are highlighted for the employees so that they control their work to be within these constraints, or report immediately deviations to appropriate personnel. The term is typically used in mill operations. West Door – 480L 675 XCN door – the Bulkhead door on the 480 m level along grid line 675 XCN – cross cut on the northing grid line on mine plans. These are the drifts with a north/south orientation.

Page 2 of 42 2

ATTACHMENT 1

Causal Factor #1: Construction on 465-944 DRE drift was started prior to having adequate emergency water pumping & treatment systems in place; CAR

# Corrective Action Recommendation (CAR) Associated Root Causes

CAR 1-1

• Cameco needs to carry out a detailed review of the decision making process leading up to approval being given to develop the 465-944 DRE prior to completing the emergency pumping and treatment expansion at Cigar Lake. This needs to include:

• a) an examination of any associated corporate and site risk assessment Standards (i.e. policies and procedures, etc.);

• b) the extent to which Cigar Lake complied with corporate Standards and regulatory constraints in deciding to proceed with the development of 465-944 DRE prior to having emergency pumping and treatment capacity in place;

• c) the extent to which Cigar Lake factored in the McArthur River and Cigar Lake Shaft #2 water inflow incidents into the decision to proceed with development in 465-944 DRE; and

• d) whether the Standards need to be revised to more exactly and strictly define the requirements that meet corporate management's expectations.

• Standard Not Strict Enough

Cameco Response

Notwithstanding the management system implementation measures that Cameco was putting into operation at the time of the inflow, the October Incident TapRooT® report found that execution of the development in the inflow area was deficient. However, Cameco would like to emphasize that the technical consultants were generally of the view that (from a rock mechanics perspective) the design, while evidently not adequately conservative for addressing the potential consequence of the residual risk of inflow, was not unreasonable. The October Incident TapRooT® report specifically notes this in the discussion of this Causal Factor in section 4.1.

Further, Cameco would like to underline that, in designing the mine, Cameco and its predecessor operator performed risk assessments on all aspects of the operation, including underground development. Based on the knowledge acquired over the lengthy test mine development and project design period, Cameco considered the risk of inflow greatest in the development of production cross-cuts and freeze hole drilling operations below the orebody. Cameco had put in place substantial preventative and mitigative measures for such an occurrence, including engineered barriers (such as ground freezing and bulkhead doors). Cameco also decided to freeze the block of ground below the ore (including where the production cross-cuts will be developed) and the orebody itself, as well as extending freezing above the orebody to mitigate the water inflow risk

Page 3 of 42 3

ATTACHMENT 1

identified for these activities. Cameco captured this in the planned mine design in place at the time of construction start-up in January 2004.

Additionally, on the north side of the mine, Cameco identified (through further geotechnical drilling commissioned during the construction period prior to the October inflow event) an irregularity in the unconformity area. As a result, Cameco decided to change the mine plan and freeze the ground in that area prior to the development of the north access drift (analogous to the south access drift where the collapse occurred) in order to mitigate the risk of water inflow during that development. Because previous geotechnical drilling had led Cameco to conclude that the unconformity location overlying the south access drift was more regular, Cameco’s analysis did not identify a change in the risk of an inflow. Accordingly, Cameco decided to proceed with the development of the south access drift with the knowledge that the planned ultimate dewatering capacity would not be fully installed until construction was nearly complete. Considering all the factors that may have contributed to the collapse of the intersection, it is evident that Cameco did not sufficiently appreciate the risk of inflow during development of the south access drift.

With respect to the required pumping and water treatment capacity, during construction, Cameco had committed to a pumping and water treatment capacity of 500 m3/hr. Subsequent to the McArthur River 2003 inflow, Cameco had modified Cigar Lake plans to increase ultimate pumping capacity to 1,500 m3/hr. This increased capacity was to be operational by the end of the construction period. The Shaft No. 2 TapRooT® report highlighted that although the pumping and water treatment capacity of 500 m3/hr was not yet in place, Cameco was in the process of installing it. Consequently, because the shaft freezing option was to be executed on the south side of the mine (without the security of the bulkhead doors), this option was made contingent on having the committed pumping and treatment capacity in place and demonstrated. In fact, the demonstration of capacity was a regulatory hold point before the CNSC would allow the shaft freezing program to proceed. Cameco satisfied this requirement in August 2006. Cameco also believed that this demonstration provided the support necessary for further development on the 465 level.

Therefore, the recommended review that Cameco is going to conduct will focus not only on an examination of the understanding of the risk assessment process, but also the measures used to resolve situations with elevated residual risk despite mitigative measures that have been put in place. Cameco’s rationale is that if the consequence or severity of the risk remains elevated, then more senior levels of Cameco’s management will be required to make decisions that take this into account. In doing so, Cameco will evaluate the adequacy of the site’s risk assessment process. Cameco will use criteria based on the corporate SHEQ program as well as the technical oversight process that Cameco’s Mining Division has implemented in February 2007. Cameco provided a description of this process in the response to the CARs developed in the Shaft No. 2 TapRooT® report.

Applicable Cameco subject matter experts will be completing this review in the third quarter of 2007. As part of this review, the subject matter experts will examine the effectiveness of key management system elements, including the following:

• roles, responsibility and authority; • change management;

Page 4 of 42 4

ATTACHMENT 1

• use of experience with respect to the implementation of change (gained from the 2003 McArthur River and Shaft No. 2 inflows;

• application of risk assessment standards and controls not only to design, but also to the operations and execution variances; and

• nonconformance, corrective and preventive action. Cameco’s objective is to ensure that mechanisms exist which can create activity hold points independent of construction or production demands. These hold point will, in turn, ensure that Cameco adequately controls the risk profile of the project (e.g., development in high inflow risk areas can only proceed if, among other contingencies, suitable pumping and water treatment capacity is operational).

Once Cameco has implemented the recommendations from the review of the decision-making process, Cameco will conduct an audit to verify the implementation using Cameco’s established SHEQ audit protocols. Cameco will provide the results of this assessment to the CNSC.

Before issuing Phases 2,3 and 4 of the Remediation Plan for approval, Cameco Cigar Lake will implement a specific risk-based project management work process entitled “Project Development Process” in Procedure 2.7.0 of Mine Facility Program Manual 01 (MFPM). The “Project Development Process” is a work process map that will describe all the major work processes in a project or work package from the initial scope definition to commissioning. Cameco Cigar Lake will also revise the Project Plan to include this process for the project. The revised Project Plan that Cameco will have in place before issuing Phases 2,3 and 4 for approval will not only include the “Project Development Process”, but also a description of the steps in the process map. In its revision to the Project Plan, Cameco Cigar Lake will require under the discussion of “Risk Management and Control” that all risks over Cameco’s acceptable criteria require a documented acceptance or rejection by at least the Cigar Lake General Manager. Cameco Cigar Lake will have this risk management and control requirement in place before any further underground development occurs at Cigar Lake.

Milestones and Timeline Summary

• Cigar Lake Mine development approval decision process review - Q2 2007 • Develop and implement control mechanisms based on corporate requirements – Q3 2007 • Post-implementation review - Q4 2007

Cross-reference to other related CARs

• CAR 1-2

Page 5 of 42 5

ATTACHMENT 1

CAR 1-2

• If and when Cameco has revised their policies and procedures in this area, they will need to communicate them to all affected personnel (managers, supervisors, workers, contractors, etc.) and ensure they are implemented

• Standard not communicated to everyone who needs to know

Cameco Response

On a priority basis, Cameco will communicate to all affected personnel any changes to policies and procedures resulting from Cameco’s response to CAR 1-1 above.

For the most part, Cameco and mine contractors recruit personnel who are experienced, skilled or educated in typical hard rock mining practices. An awareness of ground conditions is certainly the norm in hard rock mining; however, a true appreciation for the water inflow risk that can accompany a fall of ground is not typical because the situation of mining in dry basement rock with an aquifer above is relatively unique to the Athabasca unconformity-hosted uranium deposits. As noted in Section 4.1 of the October Incident TapRooT® report: “…one can argue that a higher level of concern about the potential fall of ground and water inflow related risks associated with the 465-994 DRE was appropriate.” More challenging still is fully embedding a constant awareness and vigilance for the risk of water inflow despite changes in mine technical and operational personnel.

Two key elements of Cameco’s Quality Management Program (QMP) are critical in formulating an adequate response to this issue: Training, Awareness and Competence; and Use of Experience. Cameco is in the process of implementing a corporate-wide Systematic Approach to Training (SAT) across all Canadian operations that will address much of the requirements for the Training, Awareness and Competence element of the QMP.

With respect to Use of Experience, in light of the lessons learned from this incident, Cameco recognizes that a concerted effort is required to further develop and entrain into the organization’s culture a healthy level of concern and respect for the hydrogeological regime. As such, Cameco’s Mining Division will develop a ground and inflow hazards training and awareness program for all affected persons, including corporate mining division specialists, site management, supervision, technical staff, and mining contractor personnel. This training will be in addition to the existing underground orientation required for all underground personnel.

Through this new training and awareness program, Cameco will underscore the unique geology and hydrogeology that the Saskatchewan Athabasca basin underground uranium mines are dealing with - particularly the unconformity related deposits such as Cigar Lake and McArthur River. Cameco will include the following subject material for this training:

• review of the causal factors behind the significant inflows at both Cigar Lake and McArthur River and associated lessons learned;

• environmental, safety and radiation hazards of a mine water inflow;

Page 6 of 42 6

ATTACHMENT 1

• review of ground control principles, standards and precautions; • identification of risk mitigation measures used, with discussion of their purpose; • risk assessment requirements, principles and standards; • inflow emergency response, including emergency egress and evacuation procedures; and • information on the pumping and water storage systems for the underground workings.

After developing this training and awareness program, Cameco will commence delivery with Cigar Lake as the first priority and all other Saskatchewan underground mine sites thereafter.

Cameco will manage this ground and inflow hazards training and awareness program through Cameco’s systematic approach to training (SAT). Essentially, Cameco will establish that the qualifications that this program will deliver are part of the required qualifications for all affected position profiles. Consistent with SAT, Cameco will determine clear objectives for this training; common lesson plans and supporting information; testing requirements; how soon subsequent to hiring this qualification will be required; and retraining frequency in association with developing this ground and inflow hazards training and awareness program. Once developed, Cameco’s Training and Development department will ensure that this new qualification and associated training requirement are captured in the SAT database (SAP) and referenced as appropriate in the sites’ supporting documentation to the Mining Facility Licensing Manual.

Through Cameco’s implementation of this training and awareness program, Cameco will formalize the transfer of lessons learned from the Cigar Lake and McArthur River inflows to current and future generations of mine personnel.

Recognizing that revisions to policies and procedures require an effective communication plan, in the effort to address concerns about communicating these to everyone who needs to know, by the end of June 2007, Cameco Cigar Lake will revise both External and Internal Communication Procedure (045-001) as well as the Change Control procedure (010-001) to ensure that changes are effectively managed and communicated through a required communication plan. As well, Cameco Cigar Lake will use SAT to assist in the communication plan and apply the recently implemented Cameco Incident Reporting System (CIRS), which includes an “action tracking” mechanism, to track implementations of this communication effort.

Cameco will also share lessons learned from mine inflows with the uranium and broader mining industry through professional industry organizations and associated subcommittees, such as the Saskatchewan Mining Association and the Canadian Institute of Mining and Metallurgy. In addition, Cameco will provide the opportunity for personnel from the other uranium mining company currently operating in Canada to attend this training and awareness program.


• Training in revised policies and procedures (if necessary) – during Phase 2 of remediation at Cigar Lake and all other Saskatchewan mine sites – Q4 2007

• Hazard Training and Awareness Program development – Q3 2007 • Implementation – Q4 2007 at Cigar Lake; Q1 2008 at all other Saskatchewan mine sites

Page 7 of 42 7

ATTACHMENT 1


• CARs 1-1, 2-2, 2-3, 3-1, and 3-2

Page 8 of 42 8

ATTACHMENT 1

CAR 1-3

• Cameco then needs to audit, throughout the organization, the application of the decision making process involving risk, in order to assess and verify that corporate and site Standards are being used as intended.

• Audit Program not examining all areas in sufficient depth

Cameco Response

As noted in Cameco’s response to CAR 1-1 above, Cameco will initiate an audit of the decision-making process involving risk on a priority basis at Cigar Lake, which will thereafter be expanded to all other Cameco operations in Saskatchewan, Ontario and elsewhere. As part of this effort, the newly implemented mine technical oversight process will be used as the means to ensure adequate technical rigour is applied to these reviews.

As part of developing the Cigar Lake QMP, Cameco Cigar Lake is presently reviewing Audit Procedure (060-001), which process is expected to conclude by the end of June 2007. The revised procedure will include a planned audit schedule that will regularly assess conformance to corporate standards of site’s decision-making processes involving risk.

However, in reviewing the basis of the Causal Factor in the October Incident TapRooT® report, the relationship between the root cause and this CAR is not obvious. To address the Causal Factor, Cameco will improve its corrective action process. Cameco will improve this through the application of CIRS, which includes an “action tracking” mechanism. CIRS provides an automated, auditable means by which Cameco can track and manage actions and subsequent follow-up to completion. Further, this system allows for classification and prioritization of actions on a risk basis as well as oversight reporting and tracking. In sum, resulting non-conformances will be dispositioned in accordance with the corporate Safety Health Environment and Quality audit program (SHEQ), which CIRS has been specifically designed to service.


• Audit – Cigar Lake Q4 2007; other Mining Division sites, and Fuel Services sites – Q2 2008 • Address non-conformances resulting from audits – Q4 2007


• CAR 1-1

Page 9 of 42 9

ATTACHMENT 1

CAR 1-4

• Cameco needs to ensure that all affected mine sites have approved contingency plans in place to help them effectively prepare for and aid decision making in response to acute water inflow situations. These plans need to be integrated with corporate programs and include, but should not be limited to, the elements of:

- Credible water inflow risk scenarios & mitigation measures;

- Detailed Procedures (including the need for sequencing);

- Contingency response team selection and training; - Emergency equipment and material requirements; - Communication (including audio and video); - Organizational responsibilities and authorities

(including decision making responsibilities of Command Centre and on scene personnel); and

- U/G Accounting of Personnel (tag boards, sweeping, etc.).

• No Formal Contingency Plan or Procedures

• Management System - Accountability Needs Improvement

• Communication - Communication System Needs Improvement

• Training - Practice/Repetition Needs Improvement

• Work Direction - Crew Teamwork Needs Improvement

• Human Engineering - Tools, Instruments & Materials Need Improvement

Cameco Response

Cameco’s provincial and federal regulators require Cameco to have approved emergency response plans in place. While these plans are comprehensive in dealing with more conventional emergency scenarios (such as a fire), Cameco acknowledges that these plan could be improved in relation to emergency response protocols necessary for managing emergency water inflow situations. Consequently, Cameco will review the relatively new corporate Emergency Preparedness and Response Program (EPRP), to ensure that it suitably reinforces the need for inflow considerations in site plans at Cameco’s underground mining operations where water inflow is a significant risk. Concurrently, Cameco Cigar Lake will review and enhance its emergency preparedness program to capture specific measures necessary to manage inflow scenarios associated with different scenarios (such as inflow from a standpipe or inflow from a fall of ground as experienced in October 2006). Cameco will use the experience gained from the October inflow, the 2003 McArthur River Inflow and April 2006 Shaft No. 2 inflow.

Cameco anticipates that the EPRP’s water inflow procedures would include:

• Underground water management plan to store or direct water to appropriate locations; • List of equipment required to accomplish the various activities outlined in the procedure(s); • Training requirements, including both desktop and underground drills; • Inspections, preventative maintenance and inventory of critical components; • Clear definition of roles and responsibilities during an inflow event; and • Scenarios checklist and technical criteria to assist in the decision making process during an

emergency.

Page 10 of 42 10

ATTACHMENT 1

Further, Cameco will design this program to meet the requirements of the Saskatchewan Mine Rescue Manual. Cameco will prioritize implementing the emergency preparedness measures for inflow at Cigar Lake prior to significant work being conducted in a high-risk environment. Thereafter, Cameco will undertake similar reviews at McArthur River and Rabbit Lake, which will be completed in 2007.

Given the distinctive nature of the contingency planning required when mining in the Athabasca basin, Cameco will also complete a benchmarking exercise using other mining sectors operating with similar hydrogeological risks. Through this effort, Cameco will be able to identify the best available technologies and techniques for managing inflow scenarios and thereafter evaluate their potential application in the Athabasca context. Cameco anticipates that this application of experience and evaluation of technology and techniques will include, for example the suitability of conventional incident command structure for a water inflow situation and necessary contingency equipment.

As a result of both the review and benchmarking exercises, where Cameco identifies revisions to current corporate or site EPRP or procedures, Cameco will train all personnel involved in the plan in these revised procedures.

Cameco Cigar Lake will form a Task Group that will include, at a minimum, members of the site’s OHC and Emergency Response Team / Mine Rescue Team (MRT) (could also include Mine Operations, Mine Engineering, the mine contractor(s)), which will review the site’s current contingency plans (Environmental Contingency Procedure (085-100), Radiation Contingency Procedure (098-010)) and Emergency Response Procedure (090-002)). This contingency plan Task Group’s review will focus on a water inflow scenario equivalent to the inflow experienced in October of 2006, but will take into account the documentation now in place. This Task Group will complete risk assessments on various scenarios (i.e. process map potential events and evaluate the consequent hazards), including the consideration of risk mitigation and contingencies in place at site. As part of this review, this Task Group will also perform a gap analysis to determine requirements for:

• Emergency Procedures; • Equipment; • Training; • Emergency communications; • Organizational responsibilities and authority (underground and at the Command Centre),

and • Underground accounting of personnel.

Cameco Cigar Lake will complete the review and revision to the required sections of the Emergency Response Plan and associated contingency plans and train the required personnel on these prior to significant work being conducted in a high-risk environment. Further, any deficiencies that the contingency plan Task Group detects as a result of the gap analysis will be corrected as required or prior to significant work being conducted in a high-risk environment.

Page 11 of 42 11

ATTACHMENT 1


• Corporate EPRP review, best practice benchmarking and subsequent re-training – completed and implemented commensurate with the requirements of the various remediation phases

• Similar follow-up at McArthur River and Rabbit Lake – Q4 2007


• CAR 9-3

Page 12 of 42 12

ATTACHMENT 1

Causal Factor #2: The Engineered Mine Plan for this intersection was not sufficiently conservative given the adverse geology encountered, the existing resources and conflicting priorities at Cigar Lake; CAR


CAR 2-1

• Cameco needs to develop, and put in place, a formal process to ensure that consultants’ recommendations are reviewed by the appropriate individuals and effective actions are taken.

• An integral part of this process will require obtaining and seriously considering input from appropriate site and corporate technical consultants prior to decisions being made above a defined risk level.

• The process needs to require explicit justification and an appropriate level of authorization for any deviations on actionable items arising from consultant/expert recommendations.

• Communications - Turnover process Needs Improvement

• Standards, Policies, or Admin. Controls Not Strict Enough

Cameco Response

Cameco’s Mining Division will develop a formal process to ensure that technical consultant recommendations are reviewed by appropriate individuals within Cameco and effective actions are taken. At a minimum, this process will include the following elements: • Cameco will standardize the format for the receipt of consultant reports to ensure that consultant

recommendations are clearly identified and prioritized in the reports; • Appropriate Cameco internal subject matter experts will review consultant’s reports and assign

actions arising from the recommendations to the appropriate Cameco personnel at the sites or corporate as required;

• Based on how a consultant’s recommendations impact the existing risk profile of the operation such that mitigations may not be as effective as previously considered, Cameco’s Mining Division will become engaged in the review of the suitability of the sites’ measures to address the recommendations in question;

• Cameco will enter the recommendations along with the proposed action plan into the CIRS database for the purposes of tracking the implementation of the recommendations;

• Based on a defined level of the potential “consequence” associated with a consultant recommendation (utilizing the matrices that support the QMP), Cameco’s internal subject matter experts will inform the site’s General Manager of these specific recommendations. This structure of this process will be informed by the review and analysis of the decision-making process that Cameco has committed to in its response to CAR 1-1;

• In the event there are deviations from the expert recommendations, for those recommendations at or above a defined consequence level, the site “owner” proposing the deviation must provide a justification to the General Manager and the Mining Division subject matter expert; and

Page 13 of 42 13

ATTACHMENT 1

• In consultation with the Mining Division subject matter expert, the General Manager will review the justification for the deviation and determine the appropriate course of action.

Also, Cameco’s Mining Division has recently formalized its processes for both mine technical audits and technical review meeting processes. With respect to the mine technical audits, these will include annual formal technical audits and technical reviews by subject matter experts of the following areas: • Ground control practices and geotechnical aspects impacting or likely to impact current or

planned mining; • Hydrogeology systems and practices, including grouting; • Mine dewatering systems and practices; and • Mine ventilation systems and practices. Further, each Mining Division site is now required to hold regular technical review meetings, which will serve as a peer-level management review of the following: • Mine plans and design; • Mine technical audit results; • Progress on mining method development projects; and • Any other mine technical related issues. The appropriate engineers and management from site and Mining Division will be required to attend these meetings. As established, the process for these mine technical audits and technical review meetings are modelled after the Cameco process for SHEQ audits and will include the systematic dispositioning of non-conformances through CIRS.

Cameco’s Saskatchewan mine sites will be responsible for demonstrating to the technical subject matter experts (who are also responsible for the Mining Division technical audits and reviews) that appropriate programs procedures, work instructions, technical specifications and training requirements have been updated and implemented.

Cameco Cigar Lake will also compile a list of all geotechnical, ground control and mine design related consultant recommendations. Thereafter, Cameco Cigar Lake will perform a gap analysis to determine which recommendations have not been made part of the Cigar Lake Mine Design Criteria. Those recommendations not included will formally be dispositioned with assistance from Cameco and third party experts as required, and thereafter approved by the General Manager. Cameco Cigar Lake will disposition all current and future geotechnical and ground control related consultant recommendations in accordance with the above-described process. Cameco Cigar Lake will also include a Work Instruction for dispositioning consultant recommendations in the new Mine Design Procedure. Prospectively, on a risk basis, a process of mine plan review will be formalized such that those risks which may be low, but still carry a major consequence, will require third party technical review.

Page 14 of 42 14

ATTACHMENT 1

Cameco Cigar Lake will review and update the Ground Support Procedure (100-005) based on the new Mine Design Procedure and Mine Design Criteria. Cameco Cigar Lake will also undertake a review of the technical specifications for ground support installation using both internal and third party experts and product suppliers. Thereafter, Cameco Cigar Lake will revise these specifications if required. Additionally, Cameco Cigar Lake will revise the Ground Support Procedure (100-005) to include quality checks – specifically, testing criteria and frequency. Finally, Cameco Cigar Lake will review and revise the site’s Ground Support Procedure and accompanying standards both to specifically reference ground support requirements in intersections and require the inclusion of a “Factor of Safety” in all ground support designs. Cameco Cigar Lake will formally revise the Ground Support Procedure prior to ground remediation work taking place in Phase 4 of the remediation plan for the project.


• Mining Division process for reviewing and dispositioning technical consultants’ recommendations – Q2 2007

• Mining Division Technical Audit and Technical Review process – Initiated in March 2007, with full implementation by July 2007

• Addressing of resulting non-conformances - as required on an on-going basis • Use of risk assessments – as required

Page 15 of 42 15

ATTACHMENT 1

CAR 2-2

• Cameco needs to develop and implement a set of rigorous corporate ground support Standards for mine designers to use.

• The Standards need to specify quality requirements and include any appropriate precautions relating to installation of ground support. Once the Standards have been implemented, they need to be periodically audited to ensure they are having the desired result.

• There is also the need to secure the resources to meet the requirements implicit in the Standards.


Cameco Response

It is evident from the October Incident TapRooT® report and associated Technical Reports that although the intersection ground support design was likely sufficient for the planned excavation, the design was not sufficiently conservative to accommodate the increase in span that occurred, particularly given the delays in installation of ground support.

As is the case with other Cameco underground mines in Saskatchewan, Cigar Lake does have ground support specifications for different profiles of underground excavations as well as various mine engineering and geology procedures. In addition, in 2005, Cameco hired a corporate-based rock mechanics engineer in order to provide specific technical specialist support in this discipline. However, as the Athabasca Basin hosted deposits pose unique challenges and associated risks, Cameco recognizes that an enhanced level of technical rigour is required to appropriately manage these risks. Accordingly, Cameco is addressing the need for enhanced technical rigour through strengthening three pillars of technical oversight for the Saskatchewan underground mines:

1. establishing minimum standards that all Cameco mine sites will be required to comply with;

2. implementing an enhanced program of regular technical audits and reviews in various technical specialty areas; and

3. implementing formal technical peer review meetings.

A Mining Division ground control standard will be developed that will encompass the underground Mining Division sites. Cameco will draft this standard to include ground control guidelines and requirements to be implemented by the site Mine Engineering Department, which will include quality control requirements for ground support installation as well as ground support installation procedures to be confirmed by the site Mine Operations Department. Cameco will involve third party experts as well as the mine contractor in developing installation and quality control requirements. As a final check, prior to Cameco implementing this standard, Cameco will retain a third party expert to judge the completeness of the standard and ensure the incorporation of best practices.

Following completion of the corporate standard, each Cameco underground mine site will review and revise their respective site and contractor procedures and work instructions where necessary, to

Page 16 of 42 16

ATTACHMENT 1

comply with it. Sites will incorporate any necessary revisions in their Mining Facility Licensing Manual and supporting documentation.

This standard is anticipated to include the following:

• Rock mass classification and properties; • Larger scale stability assessments; • Ground support design requirements for intersections; and • Monitoring, and quality control testing programs for ground support.

The procedures that will accompany this standard are expected to cover cable bolt installation, rock bolt installation, shotcrete application, steel sets, timbering, remedial support and associated quality control testing.

Once Cameco has deployed this standard and procedures at the underground mine sites, Cameco will assess the sites (with priority given to Cigar Lake) and identified non-conformances will be addressed. Then, as part of the Mining Division technical audit and technical review process (see response to CAR 2-1), a sub-group within Cameco’s Engineering and Projects department will conduct assessments of site programs and procedures against divisional standards. Cameco will implement this new divisional standard in conjunction with new divisional standards for the mine development cycle (see response to CAR 2-3); controlling and reporting over-excavation (see response to CAR 3-1); and mining equipment selection (see response to CAR 3-2).

Once developed, Cameco will include, as appropriate, awareness of these new standards in the ground and inflow hazards training and awareness program (see response to CAR 1-2) or as an independent SAT qualifications for appropriate personnel.

Cameco recognizes that staffing requirements are likely to change in order to implement this standard. Cameco will review and address the resulting changes to staffing requirements in conjunction with the planned Cigar Lake organizational assessment (see response to CAR 3-3).

Cameco Cigar Lake will develop the Mine Design Procedure to require internal and, if necessary, third party expert review of the long-term stability of large mine openings. Prior to re-entering the mine, Cameco Cigar Lake will have commissioned a third party expert to conduct a geotechnical assessment of the stability of the large mine openings, including the Clarifier. Cameco Cigar Lake will then feed the recommendations from this into the formal process described in the response to CAR 2-1 above.

Page 17 of 42 17

ATTACHMENT 1


• Development of standards – completed in Q3 2007 • Implementation of standards and initiation of changes to staffing (if necessary) – Q4 2007 • Audit of sites to standards – commencing in Q1 2008 • Address staffing requirements – see response to CAR 3-3


• CARs 1-2, 2-3, 3-1, and 3-2

Page 18 of 42 18

ATTACHMENT 1

CAR #

Corrective Action Recommendation (CAR) Associated Root Causes

CAR 2-3

• Cameco needs to develop and implement a set of rigorous corporate Standards for the entire mine development cycle which starts with drilling and blasting and ends with completed ground support. In addition to other important elements, the Standards need to explicitly address:

- Quality requirements; - Ground support as an element of overall ground

control; and - Geological and geotechnical mapping;

• There is also the need to secure the resources to meet the requirements implicit in these Standards.

• Provision for effective communication between Cameco mine staff and mining contractor staff should form part of the Standards, in order to achieve a team approach to the planning and execution of the ground support cycle.

• Standards, Policies, or Admin. Controls Need Improvement

• Standards, Policies, or Admin. Controls Not Used - No Way to Implement


• Communications - Turnover Process Needs Improvement

Cameco Response

Cameco acknowledges the benefits of identifying divisional minimum standards with respect to the mine development cycle. Therefore, Cameco will prepare a Mining Division standard for the entire mine development cycle for use at all Saskatchewan underground mines. This standard will start with drilling and blasting and end with completed ground support.

This standard will be risk-based and Cameco will integrate it with the new divisional standards for ground control (see response to CAR 2-2); controlling and reporting over-excavation (see response to CAR 3-1); and mining equipment selection (see response to CAR 3-2). This standard will also address the communication expectations between Cameco and mining contractor staff, as well as levels of responsibility/accountability for various persons and/or roles. Cameco will retain a third party expert to judge the completeness of this new standard and ensure that best practices are incorporated.

In order to provide assurance of the completeness of mine engineering plans, this divisional standard will also include the requirement that prior to development of new mining areas, Cameco will provide plans, schedules, the results of risk assessments and evidence of the design review process to appropriate regulatory authorities for information. This is consistent with a post-inflow condition included as part of the McArthur River mine’s CNSC operating license. The level of detail that Cameco will provide as part of these mine planning information packages will be risk dependent. Greater detail is required for higher risk mining areas, such as the mining zones in close

Page 19 of 42 19

ATTACHMENT 1

proximity to the unconformity at McArthur River and Cigar Lake. For conventional mining in basement rock hosted deposits such as at Eagle Point, less detail will be required and submitted.

To aid in implementation of this standard, Cameco will establish site-level documents modelled on existing codes of practice to guide behaviours and actions to be taken. By doing so, the concise guidance document for day-to-day use in the field will provide the key aspects of risk and ensure timely decision-making.

Once Cameco has deployed this standard and associated site-level implementation documents at the underground mine sites, the sites will be assessed by Cameco technical subject matter experts (who are also responsible for the Mining Division technical audits and reviews) (with priority given to Cigar Lake) and identified non-conformances will be addressed. Then, as part of the Mining Division technical audit and technical review process (see response to CAR 2-1), relevant Cameco technical subject matter experts will conduct assessment of site programs and procedures against divisional standards (see response to CAR 2-1).

Cameco will include, as appropriate, awareness of these new standards in the ground and inflow hazards training and awareness program (CAR 1-2) or as an independent SAT qualifications for appropriate personnel.

Cameco recognizes that staffing requirements may change in order to implement these new standards. Cameco will review and address the resulting changes to staffing requirements in conjunction with the planned Cigar Lake organizational assessment (see response to CAR 3-3).

As discussed in the response to CAR 2-2 above, Cigar Lake will update the Ground Support Procedure and Technical Specifications with respect to quality requirements for ground support installations. Also, as a consequence of this, Cameco Cigar Lake will develop the Geological and Geotechnical Information procedure (100-001) to capture the requirement for mapping as part of the development cycle. Finally, through SAT, Cameco Cigar Lake will ensure that training will be provided as required to technical and other mine staff to make certain that the procedure can be met. Cameco Cigar Lake will update these documents and implement these changes prior to resuming conventional mine development activities underground.

Additionally, before resuming conventional mine development activities underground, Cameco Cigar Lake will create a new procedure-level or work instruction document that will formalize the format for the daily contractor meeting to ensure that all required Cameco and contractor staff have reviewed and understand the ground support requirements and specifications for any new driving layout.

Page 20 of 42 20

ATTACHMENT 1


• Development and implementation of standard – Cigar Lake - complete for Phase 5, and ensure that the Phase 2-4 submissions specifically cover Cigar Lake’s plans to cover any specific ground issues; implementation at other underground operations thereafter

• Changes to staffing – as required • Audit – commencing in Q1 2008


• CARs 1-2, 2-2, 3-1, and 3-2

Page 21 of 42 21

ATTACHMENT 1

Causal Factor #3: A significantly larger span than the Engineered Mine Plan called for was excavated at the 465-944 DRE and 465-773 LCH intersection; CAR


CAR 3-1

• Cameco needs to develop, and put in place, effective corporate Standards for controlling and reporting over-excavation.

• The Standards should be developed in conjunction with the mine contractor and clearly specify how blasting, including controlled blasting, is to be carried out.

• When approved, they need to be incorporated into mine contractor's own policies, procedures and work methods.

• The implementation needs to be enforced and periodically audited against the appropriate Standards.

• No Procedure • Procedure Wrong -

Situation Not Covered • Procedures Followed

Incorrectly - Details Need Improvement

Cameco Response

By way of background, the variable nature of rock mass structure and strength, and the imprecise nature of the blasting process interacting with the rock mass, result in inherent variability in excavation profile being typical of the mine development process. Although under-excavation occurs from time to time, over-excavation where the dimensions of the excavated tunnel exceed the planned dimensions (width, height or both) to some degree is more typical. Generally, over–excavation is limited and the ground support design sufficiently conservative to support the marginally larger span. However, over-excavation can become a significant concern when the resulting increase to the span significantly reduces the factor of safety of the designed support, or when the larger excavation encroaches upon a planned rock pillar and thus reduces pillar thickness.

Cameco acknowledges the benefit of implementing tighter controls to minimize over-excavation and also to require reporting of excessive over-excavation and addressing of it promptly when it does occur. Therefore, Cameco will develop a Mining Division standard for controlling, identifying and reporting over-excavation, which will be reviewed by third party experts.

Cameco will develop this new divisional standard in conjunction with the new standards for ground support (see response to CAR 2-2); mine development cycle and associated site-level guidance document (see response to CAR 2-3); and equipment selection (see response to CAR 3-2). Cameco’s standard would include the following:

• Identification of the roles, responsibilities, and level of authority for the key personnel involved in the mine excavation process, including mine engineering, geology, Cameco supervision, contractor supervision, mine development personnel, and safety personnel;

• Requirements for mine openings to be designed with a safety factor allowance for overbreak; • Performing risk analyses in design, if required;

Page 22 of 42 22

ATTACHMENT 1

• Establishing allowable overbreak and implementing action plans if exceeded; and • Development of work instructions and/or technical specifications for controlled/perimeter

blasting in consultation with mine contractor and third party experts.

Cameco’s implementation of this standard would require:

• Incorporating this standard into the mine contractor's policies, procedures and work methods (through the use of contractual mechanisms), including technical specifications;

• Requiring regular survey measurement and reporting of overbreak; • Plotting and communicating the resulting information to required parties on a specified time

basis; • Requiring a defined communication and action process modelled on existing codes of practice

(see response to CAR 2-3) to address ground conditions or constructability in real-time; and • Following up on immediate action with a Change-In-Condition (CIC) report or other defined

formal communication protocol. The purpose of the CIC is to formally track frequency and resolution of issues to determine whether the standard or engineered work plan needs revision.

Cameco will undertake routine checks to ensure that the standard is being applied. These checks will involve regular workplace inspections by supervision and safety personnel as well as engineering inspections and geological mapping.

Once Cameco has deployed this standard and associated site level implementation documents at the underground mine sites, the sites will be assessed (with priority given to Cigar Lake) and identified non-conformances will be addressed. As part of the Mining Division technical audit and technical review process, Cameco will conduct assessments of site programs and procedures against divisional standards (see response to CAR 2-1).

As appropriate, Cameco will include awareness of these new standards in the ground and inflow hazards training and awareness program (see response to CAR 1-2) or as independent SAT qualifications for appropriate personnel.

Cameco Cigar Lake will update the Ground Support Procedure (100-005) to define when controlled blasting is to be used. Further, with the assistance of third party experts and the mine contractor, Cameco Cigar Lake will also create a technical specification that will outline the specific requirements for controlled blasting. Thereafter, Cameco will ensure the contractor’s procedures are updated to reflect the requirements of the specifications and that the appropriate material and training are available to meet the intent of the specification. Cameco Cigar Lake will implement these changes prior to resuming conventional mine development activities underground.

Also prior to the resumption of conventional mine development activities underground, Cameco Cigar Lake will update Surveying Procedure (100-006) to reflect a risk-based requirement that will define the minimum frequency with which blasted headings must be surveyed. Further, this procedure will be revised so that these survey results must be reviewed at the daily contractor meetings. Cameco Cigar Lake will also develop additional procedures and controls for reporting of over-excavation and specifying required actions to deal with over-excavation beyond stated

Page 23 of 42 23

ATTACHMENT 1

tolerances before resuming conventional mine development activities underground as part of Phase 5.


• Develop and implement standard – prior to Phase 5 of the remediation plan (resumption of development activities)

• Audit sites to the standards – on a priority basis following implementation


• CARs 1-2, 2-2, 2-3, and 3-2

Page 24 of 42 24

ATTACHMENT 1

CAR 3-2

• Cameco needs to formally review its criteria specifying when and how certain types and sizes of mining equipment are used. The criteria should be developed in consultation with the mine contractor to ensure that appropriately sized equipment is available and used at all times.

• This will require Cameco to communicate short and long term mine planning decisions to the mine contractor.

• Cameco needs to enforce the equipment selection and use criteria and periodically audit its application.

• Procedure Wrong - Situation Not Covered (no mention of jackleg)

• Procedures Followed Incorrectly - Details Need Improvement

• Communication of Policy Needs Improvement

• Drawings Need Improvement

• Resources Need Improvement

• Enforcement Needs Improvement

Cameco Response

This incident highlights the interaction of the type and size of equipment used with the size and quality of the excavation achieved. More specifically, the October Incident TapRooT® report and associated investigation Technical Reports indicate that a note calling for the use of specific equipment to develop the intersection (jackleg drills for the initial round of the cross cut) was inadvertently omitted from the design drawing and contributed to this incident. Fundamentally, this is a quality control issue at the design stage.

The Mining Division will develop a standard that addresses criteria for equipment selection and sizing. In both the short-term and long-term planning for equipment procurement use, Cameco will identify and select equipment for use based on its ability to perform the required job function. Cameco will apply this criteria to both Cameco and contractor equipment. Cameco will build sign-off controls into the equipment selection, purchase and contracting functions that demonstrate the equipment selected has been reviewed and approved as suitable to perform the required job function.

Cameco will implement this standard in conjunction with the mine development cycle standard (see response to CAR 2-3) and associated site-level documents. For identified ‘high risk’ work during construction or development activities, Cameco will put in place controls that ensure that critical pieces of equipment, as well as the trained personnel to operate the equipment, are available to complete the task. Deviations will be addressed as non-conformances.

Cameco will address the communication and supervision-related component of this CAR by implementing similar processes that are already in place at other Saskatchewan mine sites and deemed to be effective such as regular meetings (e.g. daily shift meetings, weekly planning meetings) and use of “target sheets”, signed by site mine engineering, mine operations management and contractor personnel, that provide key information.

Page 25 of 42 25

ATTACHMENT 1

Once this standard and associated procedures are deployed at the sites, Cameco will assess the sites (with priority given to Cigar Lake) and identified non-conformances will be addressed. As part of the Mining Division technical audit and technical review processes, Cameco will routinely conduct assessments of site programs and procedures against corporate standards.

As part of formalizing the daily contractor meetings discussed in the response to CAR 2-3 above, Cameco Cigar Lake will incorporate a requirement that all necessary equipment and personnel are available and prioritized to deal with high risk excavations. When each new driving layout is issued, Cigar Lake personnel will discuss and determine equipment requirements with the mining contractor. As committed to in the response to CAR 2-3 above, Cameco Cigar Lake will develop a procedure (or work instruction) defining the requirements of the daily contractor meetings. Cameco Cigar Lake will have the procedure developed and implemented prior to the resumption of conventional mine development activities underground.


• New standard developed and implemented at all Saskatchewan mines – Q4 2007 • Audit – Q1 2008 • Communication and supervision process implementation – Q3 2007


• CARs 1-2, 2-2, 2-3, and 3-1

Page 26 of 42 26

ATTACHMENT 1

CAR # Corrective Action Recommendation (CAR) Associated Root Causes

CAR 3-3

• Cameco Cigar Lake needs to review its organizational related interfaces with the MTM organization and determine what, if any, changes need to made in responsibilities, job descriptions, job titles, oversight, lines of communication, audits and assessments, etc. in order that MTM consistently carry out quality work as specified by Cameco.

• The organizational review needs to include an assessment of the advantages and disadvantages of using Contract Area Coordinators at Cigar Lake and Cameco Mine General Foremen at most other mines.

• This issue is also related to CAR 2-3.

• No Reasonable Level of Supervision


• Resourcing Needs Improvement

• Infrequent Audits and Evaluations



Cameco Response

Cameco Cigar Lake has commenced a review of the organization structure and associated roles, responsibilities, with the following objectives:

• Minimizing the number of supervisory levels between the site mining contractor management and Cameco Cigar Lake management;

• Improving lines of communication; and • Enhancing mining contractor oversight

Cameco will enhance the oversight of the mine development process through establishing the requirement for regular technical assessments to ensure changes in the geology and ground conditions are promptly identified and communicated so that the mining contractor executes quality work. Cameco will identify the assessments in a control procedure modeled on existing codes of practice (see response to CAR 2-3). Also, Cameco may retain a qualified organizational expert to conduct a third party review of the proposed structure in order to identify potential additional improvements. To provide more comprehensive technical oversight and assist in the improvement of the lines of communication, Cameco Cigar Lake project will endeavour to recruit additional technical personnel in the areas of mine engineering (qualified ground control expert) and geology. Cameco Cigar Lake project is also considering utilizing Cameco Mine General Foreman for the management of underground mining contractor activities. Cameco will make a determination in this regard before recommencing underground contractor mining development activities.

Page 27 of 42 27

ATTACHMENT 1


• Organizational changes – completed prior to commencement of Phase 2 of remediation


• CAR 2-3

Page 28 of 42 28

ATTACHMENT 1

Causal Factor #4: The specified ground support was not applied in a timely manner;


CAR 4-1

• In addition to the CAR 2-3, Cameco needs to carry out an in-depth review of the ground control program at all of its mine sites with a view to identifying organizational and technical weaknesses and missing elements.

• Effective actions need to be taken to address any identified weaknesses and missing elements. Strengths at any individual mine site need to be shared, and implemented where applicable, at other mine sites.

• Cameco needs to decide what level of authority needs to be responsible for ground support decisions. Strong consideration should be given to a senior engineer for the mine site with experience in ground control being responsible for ground support decisions.

• Cameco and MTM, at all mine sites, need to determine what, if any, changes are necessary in their current processes and how they are going to work differently together in future to ensure ground control requirements are consistently achieved.

• A process needs to be implemented whereby corporate and external ground control consultants conduct periodic audits of each site’s ground control program and report findings to the Site General Manager and the VP - Mining. The process needs to be modified such that the audit findings are effectively and formally dispositioned by an appropriate level of authority.

• Leadership for Ground Control

• Policy Not Strict Enough • Policy Confusing or

Incomplete • Communication of

Policy Needs Improvement


• Understanding of Ground Control- Learning Objective Needs Improvement



Cameco Response In conjunction with the responses to CAR 2-3, Cameco will undertake a review of the current ground control program at Cigar Lake on a priority basis and subsequently at other Cameco Saskatchewan mines. Cameco will address the identified weaknesses and missing components (including technical, procedural and organizational) on a priority basis following the review and “best practices” from other mines will also be incorporated. Cameco Cigar Lake Project will recruit an engineer for the mine site with specific expertise in ground control and will assess other organizational requirements relating to ground control as part of the broader organizational assessment described in Cameco’s response to CAR 3-3. In addition,

Page 29 of 42 29

ATTACHMENT 1

Cameco Cigar Lake will update the Work Instruction for Site Drawing Development & Review (073-002-01) to specify the levels of authority approving the ground support design depending on level of risk. Cameco, in discussion with the mining contractor, will determine the “best practices” that are currently in place at other mine sites to ensure ground control and other critical requirements are consistently achieved and that expected ground conditions or changes in observed conditions are effectively communicated between the people doing the work and the appropriate technical, supervisory and management staff. As noted in Cameco’s response to CAR 3-2, the identified measures may include items such as regular meetings (e.g. daily shift meetings, weekly planning meetings, etc.) and use of “target sheets” that are signed by site mine engineering, mine operations management and contractor personnel, that specify key information. Cameco will implement the “best practices” that are identified at the Cameco Cigar Lake project on a priority basis.. Additionally, as described in Cameco’s response to CAR 2-1, the Mining Division has recently initiated a technical audit and technical review process that specifies periodic technical rock mechanics and ground control reviews as well as audits by corporate technical specialists and external experts. The process includes formal requirements that all findings are effectively and formally dispositioned.


• Ground control programs reviewed at all Saskatchewan mines – Q4 2007 • Changes implemented – Q1 2008

• Audit sites to the standards – Q2 2008


• CARs 2-1, 2-2, 2-3, and 3-3

Page 30 of 42 30

ATTACHMENT 1

Causal Factor #5: The initial attempt to close the West Door was not completed in dry conditions as specified in the design;


CAR 5-1

• Cigar Lake needs to carry out a detailed review of all aspects of its bulkhead door closing process to identify critical elements that need to be in place and any current weaknesses and gaps in those elements. Included in this review, needs to be an examination of:

- Door Closing Policies & Procedures (including if and how the doors can be closed or opened in the presence of water);

- Deterioration of the bulkhead, the doors and components due to water, muck, etc. during normal and emergency conditions;

- Organizational responsibilities, including decision making authorities during an acute water inflow event;

- Design intent and requirements; - Related training & retraining of Cameco and MTM

personnel, including consideration for personnel turnover;

- Preventive Maintenance; - Tools and Instruments needed to ensure effective

door closing; - Communications (merits of a video link between

the Command Centre and the door closing crew, effective telephone/radio links);

- Records & document control associated with all above elements;

- Contingency plans in the event a door does not close and seal.

• Design Review - Hazard Analysis Needs Improvement

• Design Specs - Problem Not Anticipated

• Design Specs - Specifications Need Improvement

• Preventive Maintenance for Equipment Needs Improvement

• Procedures - Details Need Improvement

• Training - Practice & Repetition Needs Improvement

• Human Engineering - Tools & Instruments Need Improvement

• Human Engineering - Human/Machine Interface - Displays Need Improvement

Cameco Response In relation to Causal Factors 5 and 6 and the associated CARs, Cameco intends to structure the responses as follows: • Complete a comprehensive risk assessment (CAR 6-2);

Page 31 of 42 31

ATTACHMENT 1

• Evaluate the advantages and disadvantages of using bulkhead doors as a final safeguard (CAR 6-1); and

• Should the decision be made to keep the bulkhead doors as a viable contingency to protect the south side mine infrastructure, which in and of itself would be the result of deliberate risk consideration informed by the review to that process conducted as part of Cameco’s response to CAR 1-1 and mitigation process, develop, implement and verify the detailed controls required prior to allowing the doors to remain part of the contingency planning. In doing so, Cameco will formally consider and address the specific items noted in this CAR at that time.

With respect to implementation, Cameco recognizes that the education and training of personnel responsible for the closure and maintenance of the doors will be pivotal. Cameco will ensure that training is managed through SAT (see also the response to CAR 1-4). Also, throughout 2006, Cameco Cigar Lake has been endeavouring to build an operations quality management system (QMS). Cameco has previously described this effort in responses to CARs 2-1 to 2-4 and 4-2 to 4-4 identified in the Shaft No. 2 TapRooT® report. Cameco Cigar Lake’s efforts in this regard are consistent with the March 2006 Action Plan submitted by Cameco to disposition the mid-term license report issued by CNSC in the first quarter of 2006. A critical part of this effort, is Cameco’s ongoing development of high level process maps for all activities followed by screening level risk assessments to identify high level risk mitigations and/or the need to conduct detailed risk assessments accordingly. In following this process, Cameco is formally documenting measures to mitigate risk (i.e. specific operational, administrative and engineered controls) and then putting these measures in place (e.g. as part of the decision to proceed with borehole dewatering as part of the remediation plan for Shaft No. 2, demonstrated water treatment capacity as a prerequisite to initiating the underground freeze drilling program). Cameco Cigar Lake has established a Task Group that has a mandate specific to the bulkhead doors (e.g. maintenance and procedures for closing). As a product of this review, Cameco Cigar Lake expects that if the decision is made to retain the bulkhead doors as an important water mitigation barrier, the bulkhead doors Task Group will develop procedures and work instructions as well as any necessary change control prior to going underground.


• Risk assessment – Q2 2007 • Evaluation and decision – Q3 2007 • Program and procedure revisions – Q4 2007


• CARs 1-4, 5-2, 6-1, and 6-2

• Shaft No. 2 TapRooT® report - CARs 2-1 to 2-4 and 4-2 to 4-4

Page 32 of 42 32

ATTACHMENT 1

CAR 5-2

• Cigar Lake needs to take effective and timely corrective action to address the deficiencies and weaknesses identified in CAR 5-1 above;

• Mgm’t System - Corrective Action Needs Improvement

Cameco Response Consistent with the structure outlined in the response to CAR 5-1 above, Cameco will first conduct a review as specified in CAR 6-1. Depending on the resulting decision from the review identified in CAR 6-1, Cameco will complete a risk analysis to determine what project activities can be completed prior to implementation of the various recommendations from CAR 5-1. Cameco expects that the implementation plan will be divided into two stages and would address items as described below. If the assessment indicates that the doors should continue to be a key operational control for a future inflow, as part of contingency planning, Cameco Cigar Lake will complete the following prior to resuming routine access underground:

• update procedures to ensure original design intent is captured and implement new requirements, if necessary;

• implement through SAT, a training and qualification program for the procedures used in the operation and maintenance of the doors;

• implement necessary changes, managed through the site change management process as required to improve bulkhead closure performance;

• identify and add critical bulkhead components (including tools, supplies, etc) into warehouse inventory; and update maintenance procedures for inspection, and ensure this process is managed through the preventative maintenance system.

With respect to the bulkhead doors Task Group, Cameco Cigar Lake will complete a scope of work and then prepare a schedule. Cameco Cigar Lake will put the actions required into CIRS for tracking and follow-up.


• Please refer to the response to CAR 5-1 above


• CARs 5-1 and 6-1

Page 33 of 42 33

ATTACHMENT 1

Causal Factor #6: Upon adjusting and closing the West Door, a section of gasket separated from the door flange, resulting in water flow through the door;


CAR 6-1

• Cameco needs to carefully examine the advantages & disadvantages of using bulkhead doors as a final safeguard at Cigar Lake, considering the experience of the 2006 mine flood. Based on the results of this examination, Cameco needs to decide whether to retain the bulkhead doors as an important water mitigation barrier.

• Management System - Policy Needs Improvement

Cameco Response Cameco is reconsidering the use of the doors as a final safeguard for water inflow. This evaluation will be multi-staged and is expected to:

• Identify advantages and disadvantages of the current system and then evaluate these on a risk basis. The methodology of the risk assessment will be informed by the findings of the review of the decision making process described in Cameco’s response to CAR 1-1;

• Update the risk analysis based on updated bulkhead door controls (CAR 5-1); • Identify alternatives to using bulkhead doors, followed with a risk analysis of alternatives; • Include risks identified as part of response to CAR 6-2; • Identify new and additional control requirements based on the hazard analysis committed to

in Cameco’s response to CAR 6-2 (as well as the responses to CARs 5-1 and 1-1); and • Include emergency response requirements specific to water inflow (see response to CAR 1-

4) into the site emergency response plans and the long-range mine plan for handling and directing water inflow as described in appropriate licensing documentation.

Based on the findings of the above-described final risk assessment, Cameco will make the determination on the suitability of incorporating the bulkhead doors as part of a water inflow mitigation barrier at Cigar Lake. Cameco Cigar Lake will include this undertaking in the contingency plan Task Group’s scope of work discussed above and intends that this will be one of the first items addressed. Cameco Cigar Lake anticipates that this Task Group will complete this risk assessment by the end of June 2007.




• CARs 1-1, 1-4, 5-1, and 6-2

Page 34 of 42 34

ATTACHMENT 1

CAR 6-2

• If, after carrying out the examination in CAR 6-1, Cameco decides to continue with the use of the bulkhead doors at Cigar Lake, it needs to carry out a comprehensive hazard analysis (detailed risk assessment) as detailed in CAR 5-1 to identify:

- all significant hazards (risk scenarios) associated with the doors;

- existing controls (design, operational and maintenance);

- the relative strength or weakness of the existing controls; and

- any changes or additions necessary in the design and/or the organizational controls to ensure the bulkhead doors work as intended if and when they are needed in future.


• Design Review - Management of Change Needs Improvement



• PM for Equipment Needs Improvement


Cameco Response Because this CAR is associated with the detailed review specified in and has similar associated root causes as CAR 5-1, please refer to Cameco’s response to that CAR, as it is structured to address these root causes that are associated with the bulkhead doors. Also recognizing the importance of the efforts of the bulkhead doors Task Group, please refer to the responses to CARs 5-2 and 6-1.




• CAR 5-1

Page 35 of 42 35

ATTACHMENT 1

CAR 6-3

• Cigar Lake needs to take effective and lasting action as detailed in CAR 5-1 to address weaknesses identified in the above assessment.

• Cameco needs to periodically carry out audits of the bulkhead doors to ensure they are maintained in a state of operational readiness.


• Mgm’t System Oversight - Infrequent Audits & Evaluations

Cameco Response As detailed in Cameco’s previous response, because this CAR is associated with the detailed review specified in and has similar associated root causes as CAR 5-1, please refer to Cameco’s response to that CAR, as it is structured to address these root causes that are associated with the bulkhead doors. With respect to improving Cameco’s management system as it relates to corrective action, CIRS constitutes Cameco’s main tool to track corrective actions and is now in the implementation stage. Further, Cameco Cigar Lake has maintenance planning now in place, which includes PMs and depending on the outcome of the assessment required by CAR 6-1, the bulkheads doors will be added to these PMs. With respect to the frequency of audits and evaluation, Cameco Cigar Lake is presently reviewing Audit Procedure (060-001), which will be revised by the end of July 2007 to require auditing of maintenance programs - particularly of critical items.




• CAR 5-1

Page 36 of 42 36

ATTACHMENT 1

Causal Factor #7: The decision to force the West Door open at 08:10 hours to repair the gasket led to an increased flow through the door;


CAR 7-1

See Causal Factor #5 - CAR 5-1, 5-2. See Causal Factor #6 - CAR 6-1, 6-2, 6-3.

Design Review - Hazard Analysis Needs Improvement

Training - Task not Analyzed

Management System - Policy Not Strict Enough

Complex System - Knowledge Based Decision Required

Cameco Response As is evident from the October Incident TapRooT® report, this CAR is associated with the detailed review specified in and has similar associated root causes as CAR 5-1. Accordingly, please refer to Cameco’s response to that CAR, as it is structured to address these root causes that are associated with the bulkhead doors. The contingency plan Task Group will consider emergency response scenarios as part of its review effort. The Task Group will thereafter produce procedures and work instructions as well as necessary change control that will be implemented by Cameco Cigar Lake prior to going underground.


• Please refer to the responses to CAR 5-1 and CAR 1-4


• CARs 1-4 and 5-1

Page 37 of 42 37

ATTACHMENT 1

Causal Factor #8: The decision to force the West Door open at 10:35 hours to repair the gasket led to debris being caught in the door which caused a significantly increased flow through the door;


CAR 8-1



Training - Task not Analyzed

Management System - Policy Not Strict Enough

Complex System - Knowledge Based Decision Required

Cameco Response Again, as is evident from the October Incident TapRooT® report, this CAR is associated with the detailed review specified in and has similar associated root causes as CAR 5-1. Accordingly, please refer to Cameco’s response to that CAR, as it is structured to address these root causes that are associated with the bulkhead doors. Please also refer to the response to CAR 7-1 above as this response provides additional detail with respect to the efforts of the contingency plan Task Group.




• CARs 1-4 and 5-1

Page 38 of 42 38

ATTACHMENT 1

Causal Factor #9: Forcing the door open at 11:09 hours resulted in the door being left open;


CAR 9-1



Cameco Response Again, as is evident from the October Incident TapRooT® report, this CAR is associated with the detailed review specified in and has similar associated root causes as CAR 5-1. Accordingly, please refer to Cameco’s response to that CAR, as it is structured to address these root causes that are associated with the bulkhead doors. Please also refer to the response to CAR 7-1 above, as this response provides additional detail with respect to the efforts of the contingency plan Task Group.




• CARs 1-4 and 5-1

Page 39 of 42 39

ATTACHMENT 1

CAR 9-2

• Cameco needs to carry out a detailed risk assessment to:

- identify the personnel safety related hazards experienced in the October, 2006 incident;

- identify the availability and effectiveness of controls used to manage personnel safety related risk; and

- make recommendations for improvements;

• Management System - Contingency Plan and Procedure Not Available

Cameco Response As part of the effort to satisfy the requirements specified in both this CAR and CAR 1-4 (which call for all Cameco mine sites to have approved contingency plans in place to prepare for acute water inflow situations (see above)), Cameco prepared a detailed risk assessment (the Assessment). The reasons for preparing the Assessment were twofold:

• One of the Cameco assessors was able to conduct interviews of approximately 20 of the employees and contractors who were involved in the October 2006 incident within a few days of its occurrence; and

• These assessors were not only familiar with the controls that should be in place to manage personnel safety-related risk, but also understand how these are incorporated into Cameco’s integrated SHEQ system.

However, recognizing the gravity of this incident as a corporate site had to be partly evacuated under emergency circumstances, that a serious injury was a possibility (e.g. drowning, impact injury, misadventure) and that CAR 9-2 is integral to the response to CAR 1-4, Cameco determined that the Assessment would be further reviewed in light of findings from the evaluation of the decision making process described in CAR 1-1. Further, Cameco decided that the Assessment could be improved through the application of internal expertise on risk and management systems so that this knowledge can be brought to bear in both assessing the situations described and developing appropriate corrective actions. Cameco will provide the Assessment to the CNSC and Sask Labour for review when it is finalized. Cameco expects that through this process, the Assessment will provide a robust set of recommendations. Accordingly, Cameco expects that this work will be completed in Q2-2007, with actions resulting from recommendations managed through Cameco’s Incident Reporting System (CIRS). Cameco then expects that implementation of the actions necessary to support the remediation will be completed during Phase 2 of remediation. Further, Cameco will provide updates in relation to Cameco’s progress on these actions at the Cigar Lake routine regulatory issues meeting, currently held on an almost monthly basis. After completing this process, Cameco will ensure that follow up to these actions are captured in the internal SHEQ audit program and that audits will be completed through the planned cycle of that program. Given the inflow risk, Cameco will place a priority on Cigar Lake’s program such that

Page 40 of 42 40

ATTACHMENT 1

CARs can be implemented prior to personnel re-entering the mine (i.e. during Phase 2 of the remediation plan), followed by audits at McArthur River and Rabbit Lake before the end of the third quarter of 2007.


• Review of the Assessment – April 2007 • Revise site programs – May 2007 • Recommended corrective actions in the revised assessment finalized and entered into CIRS –

July 2007 • Address the resulting corrective actions – completed during Phase 2 of remediation


• CAR 1-4

Page 41 of 42 41

ATTACHMENT 1

CAR 9-3 • Cameco needs to ensure that all affected mine sites

develop and implement approved contingency plans for addressing personnel safety as part of an acute water inflow incident. The recommendations from CAR 9-2 need to be incorporated into each site’s contingency plan as defined by CAR 1-4.


Cameco Response Following the completion of the safety assessment for the addressing of CAR 9-2, Cameco will incorporate the results into the corporate and respective sites’ contingency plans (see also response to CAR 1-4).


• Please refer to the response to CARs 9-2 and 1-4


• CARs 1-4 and 9-2

Page 42 of 42 42

TapRooT® Investigation Report

Mine Flood Incident Cigar Lake Uranium Mine

October 22, 2006

Brian J. Locker KnoW Problem Inc.

April, 2007

of 96 2

Glossary of Terms

Area Coordinator Cameco position at Cigar Lake responsible for interfacing with MTM personnel underground. Somewhat equivalent to Mine General Foreman position at other Cameco mines

Bulkhead

A water control system consisting of a mass concrete plug with several components, including a stress transfer cylinder cast into the concrete, multiple service pipes passing through the concrete, a removable bridge and a passageway through the centre of the plug which can be closed and sealed with a hinged door. The Bulkhead at 480L 725 XCN houses the East Door, and the Bulkhead at 480L 675 XCN houses the West Door.

CESL Cominco Engineering Services Ltd. CESL designed the Bulkhead doors for the Cigar Lake mine

CLMC Cigar Lake Mining Corporation CLMC operated the Cigar Lake mine until 2002

Command Centre On site, on surface centre which housed the site crisis management team

Door Closing Procedure

Underground Water Control Bulkhead Door Closing document (QMS No. 199-001-01; Revision 2; issued February 22, 2006)

DRE Drift East

E&P Corporate Engineering & Projects (Cameco head office)

East Door 480L 725 XCN door – the Bulkhead door in the 480 m level along grid line 725.

EMS Croscan Engineering Management Services Croscan Ltd. The consultant hired to investigate aspects of the door failure

Engineered Mine Plan The driving layouts issued to MTM for construction

General Arrangement The agreed upon, licensed plan for development of the mine

General Manager Cigar Lake General Manager, who also acted as Head of on-site Command Centre

Golder Associates Golder Associates Ltd. Geotechnical consultant for Cigar Lake

of 96 3

Head of Command Centre

Cigar Lake General Manager acted as Head of Command Centre

Itasca Itasca Consulting Canada Inc. Independent rock mechanics consultant

LCH Launch Chamber

LHD Load Haul Dump Unit (also known as “scoop tram”)

MCC Room Motor Control Centre (houses mine electrical systems)

MDS Mine Development System (Single Shield Tunnel Boring Machine)

MTM Mudjatik Thyssen Mining The main mining contractor on site

PBQD Parsons Brinckerhoff Quade & Douglas Inc. Provided geotechnical recommendations for the Cigar Lake mine design in the late 1990’s

PM Preventative Maintenance

Q Quality (according to Barton’s Classification System)

RFI Request for Inspection

RM Rock Mass Classification Number

SCBA Self Contained Breathing Apparatus West Door 480L 675 XCN door – the Bulkhead door on the 480 m level along

grid line 675.

WL Working Levels

XCN Cross Cut North

of 96 4

Table of Contents

1.0 EXECUTIVE SUMMARY............................................................................................................ 5 2.0 OVERVIEW OF THE INVESTIGATION PROCESS ............................................................ 11

2.1 INVESTIGATION SCOPE............................................................................................................... 11 2.2 ROOT CAUSE ANALYSIS PROCESS.............................................................................................. 11 2.3 INFORMATION COLLECTION (I.E. “WHAT HAPPENED”) .............................................................. 11 2.4 CAUSAL FACTOR (PROBLEM/ISSUE) DEFINITION ....................................................................... 12 2.5 ROOT CAUSE ANALYSIS............................................................................................................. 12 2.6 CORRECTIVE ACTION RECOMMENDATIONS ............................................................................... 12

3.0 EVENTS LEADING UP TO THE INCIDENT......................................................................... 13 4.0 CAUSAL FACTORS AND SUPPORTING INFORMATION ................................................ 23

4.1 CAUSAL FACTOR #1 – CONSTRUCTION ON THE 465-944 DRE WAS STARTED PRIOR TO HAVING ADEQUATE EMERGENCY WATER PUMPING AND TREATMENT SYSTEMS IN PLACE ...................................... 23 4.2 CAUSAL FACTOR #2 – THE ENGINEERED MINE PLAN FOR THIS INTERSECTION WAS NOT SUFFICIENTLY CONSERVATIVE GIVEN THE GEOLOGY ENCOUNTERED, THE EXISTING RESOURCES AND CONFLICTING PRIORITIES AT CIGAR LAKE ................................................................................................ 25 4.3 CAUSAL FACTOR #3 – A SIGNIFICANTLY LARGER SPAN THAN THE ENGINEERED MINE PLAN CALLED FOR WAS EXCAVATED AT THE 465-944 DRE AND 465-773 LCH INTERSECTION......................... 27 4.4 CAUSAL FACTOR #4 – THE SPECIFIED GROUND SUPPORT WAS NOT APPLIED IN A TIMELY MANNER .................................................................................................................................................. 33 4.5 CAUSAL FACTOR #5 – THE INITIAL ATTEMPT TO CLOSE THE WEST DOOR WAS NOT COMPLETED IN DRY CONDITIONS AS SPECIFIED IN THE DESIGN ......................................................................................... 37 4.6 CAUSAL FACTOR #6 – UPON ADJUSTING AND CLOSING THE WEST DOOR, A SECTION OF GASKET SEPARATED FROM THE DOOR FLANGE, RESULTING IN WATER FLOW THROUGH THE DOOR ........................ 42 4.7 CAUSAL FACTOR #7 – THE DECISION TO FORCE THE WEST DOOR OPEN AT 08:10 HOURS TO REPAIR THE GASKET LED TO AN INCREASED FLOW THROUGH THE DOOR................................................... 47 4.8 CAUSAL FACTOR #8 – THE DECISION TO FORCE THE WEST DOOR OPEN AT 10:35 HOURS TO REPAIR THE GASKET LED TO DEBRIS BEING CAUGHT IN THE DOOR WHICH CAUSED A SIGNIFICANTLY INCREASED FLOW THROUGH THE DOOR .................................................................................................... 53 4.9 CAUSAL FACTOR #9 – FORCING THE DOOR OPEN FURTHER THAN INTENDED AT 11:09 HOURS RESULTED IN THE DOOR BEING LEFT OPEN ................................................................................................ 55

5.0 CORRECTIVE ACTION RECOMMENDATIONS ................................................................ 57 APPENDIX 1 - CAUSAL FACTORS - RELATIONSHIP TO EACH OTHER & THE CIGAR LAKE MINE FLOODING ........................................................................................................................ 68 APPENDIX 2 - SNAPCHART® OF EVENTS & CONDITIONS SHOWING WHAT HAPPENED LEADING UP TO AND FOLLOWING THE MINE FLOOD INCIDENT AT CIGAR LAKE ON OCTOBER 22, 2006 ................................................................................................................................... 74

of 96 5

1.0 EXECUTIVE SUMMARY The Cigar Lake underground uranium mine is situated in Northern Saskatchewan, 70 km from McClean Lake and 660 km north of Saskatoon. Production at Cigar Lake was expected to begin in 2008. Ore at Cigar Lake will be broken with jets of pressurized water and removed in slurry form through steel piping. The ore will be pumped to surface and loaded into special containers and trucked 70 km to McClean Lake for processing. An organization chart, showing many of the relevant positions in the Cameco and MTM organizations, appears below:

AreaCo-ordinator

Sr. AreaCo-ordinator

ConstructionManager

GeneralManager

Cigar Lake

ChiefMine

Engineer

ChiefGeologist

GroundControl

Engineer

SeniorGeologist

SeniorMine

Engineer

ProjectManager

Mine Dept.

MineManager

MineCaptain

Miners(Approx 14)

ShaftSupervisor

ShiftBoss

MineSuperintendent

SurfaceSupervisor

Cameco MTM

Organization Chart - Cigar Lake

Normal Lines ofCommunicationBetweenCamecoand MTM

On September 22, 2006, MTM recommenced development on the 465-944 DRE by blasting the 1st of 6 rounds. Development had been stopped in 1999 when the cutter wheel of an MDS had been concreted into a cross-cut on this elevation as a result of a small water inflow event. Construction was restarted on the 465-944 DRE prior to having adequate emergency water pumping and treatment systems in place. On October 11, 2006 MTM drilled and blasted the 465-773 LCH intersection slash (5th round). They created a significantly larger span than the Engineered Mine Plan called for at the 465-944 DRE and 465-773 LCH intersection. MTM slashed the cross-cut using a jumbo drill and intersected unanticipated geological structures. The slashing round

of 96 6

created a larger opening than specified in the Engineered Mine Plan. Launch chamber openings were intended to be drilled with jackleg drills, rather than a jumbo, in order to control over-excavation. The actual span generated was surveyed to be 10 m. The Engineered Mine Plan specified a 7 m span, and the ground support that had been specified for the intersection was only intended to support a 7 m span. Several personnel interviewed indicated that controlled blasting techniques should have been used, but this was not consistently done. Following the 5th round in particular, MTM did not apply the specified ground support (bolt, screen and shotcrete) in a timely manner. An underground inspection, at the request of MTM, was carried out by a Mine Engineering staff member on October 15, 2006. This indicated that ground support installation was only 25% complete. An October 15, 2006 non-conformance report (issued as a result of that inspection) indicates that 106 hours had passed with only 25% of required bolts being in place, and with no shotcrete having been installed. The Engineered Mine Plan stated that "all ground support to be installed within 72 hours after blasting.” On October 17, 2006 bolting was completed in 465-773 LCH and shotcrete was being applied. Records indicate that MTM began to install shotcrete 144 hours after the 5th round was blasted. The 72 hour time period was well surpassed. On Thursday, October 19, 2006 MTM noticed spalling of shotcrete in the area as a result of rock movement. At this time, it was observed that the east pillar of the launch chamber was undercut by 1.5 m. There was visible loose rock where shotcrete fell. Also, soft ground and big blocks fell from the face in 465-773 LCH. This was the first evidence of a large wedge requiring deep support. As there had been no prior geological mapping of the 465-773 LCH, the wedge went unmapped until this point, and was therefore unsupported for a prolonged period of time. On Friday, October 20, 2006 MTM modified ground support requirements for the intersection with input from E&P. On Saturday, October 21, 2006 the installation of straps and bolts was completed. The rock bolts were producing small amounts of water. Immediately prior to the ground fall, two high angled faults were mapped in the 773 LCH/XCN. At least one of these could have been identified prior to blasting the 5th round. However, it has not been site Geology’s practice to do detailed mapping in development areas. Consultant recommendations identify the importance of detailed geological mapping On Sunday morning, October 22, 2006 about 10:00 hours, MTM observed more spalling of shotcrete and indications of rock movement. The Area Coordinator was contacted and went to look. He saw evidence of ground movement over a large area. He then limited access to the area. He decided the drift would need to be concreted in. At approximately noon on October 22, 2006 a fall of ground occurred, accompanied by a large inflow of water, estimated to be approximately 340 m3/hr. At the time, the underground pumping capacity of the mine was in the order of 500 m3/hr. At approximately 16:00 hours on October 22, 2006 the flow rate was estimated to have increased to between 1,400 and 1,500 m3/hr. Consultants suggest that the water flow increased due to erosion of loose material, probably from the vicinity of the

of 96 7

unconformity. Hourly monitoring of water levels and flow rates was conducted. At this point, the net water gain in the mine was about 1000 m3/hr. Management members left Saskatoon at 19:00 hours to fly to site. At 20:50 hours, a message was received by pilots that site personnel believed the efforts should be focused on preparing to close the East and West Doors. The General Manager instructed the site personnel to abandon temporary bulkhead construction and prepare the East Door and the West Door for closure. The order was given to ready the north side of the mine for door closure, which involved isolating electrics as well as any other conduits into the area, and salvaging readily available equipment. It was critical that the north side of the mine be swept to ensure all personnel were accounted for prior to closing the East and West Doors. All personnel were accounted for and removed from the north side of the mine by 02:30 hours on October 23, 2006. The mine sweeping was described by several interviewees as professional and effective. At 04:58 hours, records indicate that MTM closed the East Door. Water from the inflow had been reporting to the East Door the entire time, and the water was approximately 12 inches deep at the East Door when it was closed. MTM had some minor difficulty with door alignment during the initial close, but they leveraged the door into place. The door formed a tight seal with little to no leakage. At 05:10 hours, MTM attempted to close the West Door. The door was observed as swinging nicely. No water was flowing during the initial attempt to close this door. As the door neared closing, the MTM supervisor noticed that the door was not closing squarely. They pushed it open with an LHD unit and adjusted the door. The water flow had now begun to report to the West Door. When tightening up the come-alongs attached to the inside of the West Door, the crew noticed a section of gasket had separated from the West Door and was hanging on the inside of the door, creating about a 3/16 inch gap. The piece of gasket was estimated as being approximately 4 feet in length by one individual and resulted in water leakage through the door. The gasket was still connected at one end to the door. The piece of gasket, one of four sections of gasket around the edge of the West Door, may have been dislodged by the flowing water while closing the door. The underground crew was unable to establish a water tight seal around the door. At approximately 06:00 hours, one visual estimate of the flow rate through the West Door was 200m3/hr. The initial plan of the underground crew was to pump concrete through the door openings and behind the door. The MTM Supervisor at the door did not want to re-open the door with water building behind it. During a phone call at 06:16 hours, the Head of the Command Centre instructed the MTM and Cameco supervisors at the West Door to try to insert gasket material into door rather than pump concrete. The MTM Supervisor estimated that the depth of water on the door was about 12 inches at this point. At 06:45 hours, the Area Coordinator was sent underground to coordinate efforts. He carried gasket material with him. A crew shift change occurred at this time. At 08:10 hours, after completing their door opening preparations, an MTM Supervisor pushed the West Door open slightly using an LHD in an attempt to insert the gasket material. However, they were immediately forced to close the door due to the intense water spray caused by opening the door against the water behind it. The MTM

of 96 8

Supervisor operating the LHD was stung in the face by spray coming through door. As a result of the intense spray, the workers could not gain access to attempt to reinsert the gasket material. When the LHD backed away, the door slammed shut. The Command Centre believed that a fully intact gasket in the door was necessary for the leakage to be handled by the pumping and treating system. Because of this, they decided on what they believed to be a necessary action, which resulted in further deterioration of the situation. The decision to force the door open at 08:10 hours to repair the gasket caused more of the gasket to become separated. This resulted in a larger flow. The Area Coordinator measured the velocity, and the Command Centre estimated a flow of 800 m3/hr through the West Door following the 08:10 hours opening. A proposal was then made to insert burlap through the Bulkhead pipes in an attempt to seal the leak or restrict the flow. The plan was then to grout behind the West Door and support the gasket. While nearing completion of their preparations for the burlap and grout attempt, the Head of the Command Centre instructed the Area Coordinator to open the door a minimum of 2 feet, let the water levels equalize for a few minutes, and then attempt to insert the gasket once the flows at the door had stabilized. At this point, the water level behind the West Door was estimated by the underground crew to be approximately 4 feet above the floor. At approximately 10:35 hours, the underground crew opened the West Door at least 2 feet using an LHD. At this point, 2 ½ hours had passed since the last door opening. A large rush of water immediately came through the door from the water backed up behind the door. An MTM supervisor noticed that some key electrical equipment for some dewatering pumps was going to be lost if the door was not immediately closed. The MTM Supervisor responded to the West Door on a skidsteer loader and had the crew immediately close the door. For a second time, the decision to force the door open to repair the gasket led to a worse seal position and a larger leak. This time, a rubber or plastic object had been caught in the door and this made the flow rate even larger. When the Area Coordinator communicated this status to the Command Centre, all agreed that a final attempt to dislodge the object from the door was necessary or the mine would be flooded. The flow rate through the West Door was now considered too high for any other option to be feasible. An MTM miner was requested by his shift boss to find four other workers trained to wear SCBA and to make a final attempt to close the West Door. The MTM crew was briefed by the Area Coordinator, and was instructed to tie a piece of rope to the object pinched in the door, open the door very slightly and tug the object loose. Three MTM workers went to the door for the final door opening attempt at 11:09 hours. One worker operated the LHD and the other two positioned themselves at the door. The LHD operator needed to use all the force of the LHD to get the door to crack open against the water. This may have resulted in the door being pushed open farther than intended. A large rush of water came through the door, and one of the workers lost his footing and was temporarily submerged before regaining his footing and being assisted to nearby incline by the fourth and fifth MTM workers.

of 96 9

Force from the flowing water exerted on the inside of the West Door made it impossible to close, and resulted in the door being left open. Once the door was open to this extent, the workers could not pull it closed. The LHD, which was being affected by the water, had limited traction and the operator experienced great difficulty attempting to close the West Door against the pressure being exerted from the flowing water. The remaining MTM worker at the door could not withstand the flow rate and was forced to retreat. He was struck with large debris (toolboxes, timbers, etc.) and had water coming over his shoulders. This indicates that the water level behind the door was at least 5 feet deep. The workers recall being told in their pre-job briefing to expect a water level of roughly 2 to 2 ½ feet. The worker operating the LHD then attempted to close the West Door, but could not. In attempting to pull the door closed, the LHD broke the ¼ inch wire rope it was using. The LHD operator turned off the LHD, jumped from the machine, and was helped to the nearby incline by the others. At this point, the Area Coordinator, waiting with others near the #1 Shaft, consulted with the miners and decided to evacuate the mine. The Area Coordinator reported the situation to the Command Centre at 11:14 hours. The General Manager agreed with his decision to evacuate the mine. The Area Coordinator called for the cage. The Hoist Operator staged the cage just above the 480 level access and the workers used a ladder to access the cage. A total of 21 workers on the 480 level climbed up the ladder into the cage. The cage stopped at the 420 level to pick up 3 more workers, who had been monitoring the pumping station. The total number of workers on the final cage exceeded the posted occupancy limit, but was well within the cage’s lifting capability. The cage reached surface at approximately 11:30 hours and services were shut off to the mine. The miners were instructed to tag out and hand in all their radiation monitoring devices. A radiation monitoring device was placed at the shaft collar and the mine was allowed to flood. Consistent with all large incidents, and most small ones, there is no single cause. The investigation has identified 9 major problems (referred to as “Causal Factors”) that preceded the incident. If these problems had not existed, there is a reasonable probability that the Cigar Lake fall of ground and subsequent flooding of the mine would either not have occurred or the consequences would have been less severe. It is critical for the reader to understand that all 9 of these Causal Factors had to have occurred for the Cigar Lake mine to have flooded on October 23, 2006. A discussion and basis for the 9 Causal Factors appears in Section 4 of the report. Appendix 1 illustrates the relationship between the 9 Causal Factors. The Causal Factors are: 1. Construction on the 465-944 DRE was started prior to having adequate emergency

water pumping and treatment systems in place. 2. The Engineered Mine Plan for this intersection was not sufficiently conservative

given the geology encountered, the existing resources and conflicting priorities at Cigar Lake.

of 96 10

3. A significantly larger span than the Engineered Mine Plan called for was excavated at the 465-944 DRE and 465-773 LCH intersection.

4. The specified ground support was not applied in a timely manner. 5. The initial attempt to close the West Door was not completed in dry conditions as

specified in the design. 6. Upon adjusting and closing the West Door, a section of gasket separated from the

door flange, resulting in water flow through the door. 7. The decision to force the West Door open at 08:10 hours to repair the gasket led to an

increased flow through the door. 8. The decision to force the West Door open at 10:35 hours to repair the gasket led to

debris being caught in the door which caused a significantly increased flow through the door.

9. Forcing the West Door open at 11:09 hours resulted in the door being left open.

of 96 11

2.0 OVERVIEW OF THE INVESTIGATION PROCESS

2.1 Investigation Scope The investigation examined all of the relevant events and conditions leading up to and following the mine flooding incident at Cigar Lake on October 22, 2006. The investigation examined events as far back as 1990 when the Bulkhead doors for the mine were designed and installed. It also considered both water pumping and water treatment capability and performance. Both basic and root causes of the inflow incident were identified, as well as corrective action recommendations to significantly lessen the chances of this type of incident occurring in the future, either at Cigar Lake or at any other Cameco mining operations.

2.2 Root Cause Analysis Process The investigation was conducted using the TapRooT® Root Cause Analysis process. This process was developed in 1988 and is internationally recognized and used by organizations from many different industries. The investigation process consisted of four main steps, namely, a determination of: 1. What happened (SnapCharT®); 2. Issues or Problems (called Causal Factors); 3. Why the incident happened (Root Cause Analysis); and 4. Corrective Action Recommendations.

2.3 Information Collection (i.e. “What Happened”) Numerous individuals from various levels of the two organizations involved (Cameco and MTM) were interviewed by both the TapRooT® investigation and by technical consultants as part of the information collection process. Some of those interviewed were directly involved in the events leading up to the fall of ground and subsequent mine flooding incident. Others were more indirectly involved, and were interviewed for their technical and background expertise and knowledge. Numerous reports, detailed correspondence and photos were also reviewed and considered. An important information source for this investigation consisted of reports from several technical consultants commissioned by Cameco to examine specific areas. The two key areas where input from consultants was extensively drawn upon are: • geotechnical aspects of the fall of ground and subsequent water inflow; and • failure of the West Door to work as intended. Relevant information from the above sources was assembled into a detailed SnapCharT®, creating a time-ordered listing of relevant events and associated conditions. The complete SnapCharT® is detailed in Appendix 2 of this report.

of 96 12

2.4 Causal Factor (Problem/Issue) Definition 9 Causal Factors were identified for the water inflow incident. Causal Factors are general problems or issues. The Causal Factor numbering reflects their order in time sequence and NOT their relative priority. This time sequencing of Causal Factors may be observed in Appendices 1 and 2. There is no prioritization of Causal Factors. The premise is that if any one Causal Factor had been removed or significantly changed prior to the incident, there would be a good chance the incident would not have occurred or its consequences would have been significantly reduced. A discussion of and basis for each Causal Factor appears in Section 4 of the report. A visual illustration of the 9 Causal Factors, and how they relate to each other and the water inflow incident, may be seen in Appendix 1. Each Causal Factor is associated with, or more accurately the result of, numerous conditions. The conditions provide additional information and help to explain why the Causal Factor existed.

2.5 Root Cause Analysis The TapRooT® Root Cause Analysis process calls for each Causal Factor to be analyzed for root causes using the TapRooT® Root Cause Tree. The process requires the investigator to identify as many root causes as are supported by the information collected. It is important to note that there is no ‘root - root cause’ to an incident (or to a Causal Factor). Typically, there are several Causal Factors associated with an incident and for each Causal Factor, there are several root causes. The root causes detail why the Causal Factor was allowed to exist. The Cigar Lake mine flooding incident was typical in this regard. Identification of valid root causes permits the formulation of effective and practical Corrective Action Recommendations (CARs).

2.6 Corrective Action Recommendations A total of 21 Corrective Action Recommendations (CARs) were developed to address the root causes stemming from the 9 identified Causal Factors. These are detailed in a Corrective Action Matrix format in Section 5 of this report.

of 96 13

3.0 EVENTS LEADING UP TO THE INCIDENT When Cigar Lake was first started, it was operated by the Cigar Lake Mining Corporation (CLMC). The site was a Joint Venture, with Cameco and AREVA being the major partners. Cigar Lake is a challenging resource to mine. There are many recognized geotechnical and hydrological challenges to overcome. Several consultants have been used over the years for geotechnical advice and assistance, including Golder Associates and PBQD. The first activities involved testing new mining methods since the geotechnical and hydrological challenges required a unique method of extracting uranium. The design and installation of Bulkhead doors took place in the years 1990/91. The doors were intended as a major physical control for potential water inflow. The design was carried out by CESL. There was development of the 465-944 DRE and some cross-cuts in the early 1990s. Conventional drill and blast methods were used in the 465-944 DRE and an MDS and / or Roadheader was used in the crosscuts as bad ground was found there. The ground conditions found in the crosscuts to the north of the drift were described as mud-like. Ground support in the cross-cuts consisted of steel sets and shotcrete. One metre advances were taken with a Roadheader, and then immediately shotcreted. Around October 1, 1999, the cutterhead of a tunnel boring machine (the MDS) had to be abandoned in the 465-743 XCN when the development crew intersected bad ground, resulting in a ground fall and a small water inflow event. A decision was made to concrete the cutterhead of the MDS in place to form a plug. At this time, development on the 465m level halted. Development was not recommenced until September, 2006. Near the beginning of 2002, the operating responsibility at Cigar Lake was taken over from CLMC by Cameco. The existing CLMC management team remained in their positions. On March 22, 2002, a report was issued documenting a geotechnical review that had been conducted by Golder Associates. The purpose of this review was to validate the mine design. Two recommendations in particular were made that proved relevant to the October 22, 2006 fall of ground. Golder Associates stated, in their 2002 report, that: "controlled blasting and careful controlled excavation approaches will need to be adopted in areas of poor rock quality.” They also recommended using cable bolts in all mine development intersections. Turning the clock forward to 2005, Cigar Lake has had chronic challenges getting ground support installed in a timely manner. On December 7, 2005, the Construction Manager wrote an email to MTM regarding ground support efforts. In this email, he indicated that ground support installation was not meeting time specifications. Personnel interviewed in this investigation point to two factors in particular that affected timely ground support installation: • Inadequate MTM manpower to meet requirements linked to contract specifications;

and

of 96 14

• Restriction of equipment use by ventilation system requirements resulted in the necessity for prioritization of tasks.

Prior to October, 2006, mine planning and scheduling was being performed day to day. The emphasis had been on surface construction. MTM was carrying out mine development in several areas, and this resulted in the need to juggle priorities and resources. Ground support often suffered as a result. In February, 2006, a corporate audit of water inflow potential was completed by E&P. This audit was carried out at Rabbit Lake, McArthur River and Cigar Lake. It had been requested by Cameco’s VP-Mining as a result of the 2003 McArthur River water inflow. In the Cigar Lake audit findings, recommendations were made to take special precautions for mining 465 level access drifts. The investigation found no formal dispositioning of the February, 2006 audit recommendations on water risks at Cigar Lake. Site management may not have appreciated the warnings, as the audit report distribution was limited, and management believed the report applied to post-construction, not to development. On September 22, 2006, MTM recommenced development on the 465-944 DRE by blasting the first of six rounds. Records indicate that MTM began to install shotcrete 84 hours after this first round was blasted. Construction was restarted on the 465-944 DRE prior to having adequate emergency water pumping and treatment systems in place. The plan was to upgrade nominal emergency pumping and treating capability to 1,500 m3/hr as per lessons learned from the McArthur River inflow. It is important to note that just prior to beginning development in this drift, site Mine Engineering began to explicitly place a requirement on their driving layouts that ground support needed to be in place within 72 hours. The 72 hour time requirement was negotiated between Cameco and MTM as “reasonable and practical,” rather than technically based. These time requirements were understood by key personnel to be guidelines, rather than firm requirements. Others we spoke to, including Mine Engineering, indicated the time requirements were requirements, not guidelines. The prescribed ground support was consistent with RM 2/3 (i.e. poor to fair) ground. During this period, Geology department priorities were directed toward the freeze hole program. They gave less priority to detailed mapping of development drifts. On September 28, 2006 MTM drilled and blasted the 2nd round in the 465-944 DRE, including the turnout on the south side of the drift. They began to install shotcrete 84 hours after the 2nd round was blasted. On that same date, a geotechnical audit was issued by E&P. The report stressed the importance of timely ground control in general. MTM drilled and blasted the 3rd round in the 465-944 DRE on October 3, 2006. Area Coordinator records indicate they began to install shotcrete 72 hours after the 3rd round was blasted. On October 7, 2006 MTM drilled and blasted the 4th round in the 465-944 DRE and began to install shotcrete 48 hours after the round was blasted. In taking this round, they went past the 465-773 LCH intersection. Cigar Lake did not plan or provide for additional support requirements for this intersection. A 5 m cable bolt recommendation had been made by one consultant. Cameco decision makers at Cigar Lake were extremely sensitive to being in close proximity to the unconformity, and advised that 5 m cable bolts were not a realistic option. No equivalent ground control method was

of 96 15

considered by Cigar Lake. The investigation also learned, during interviews, that several MTM personnel (and one Mining Engineer) were unaware that the 944 DRE was close to the unconformity. Other relevant factors include that past experience in the 465-944 DRE did not indicate problems with ground support in intersections in RM 2/3 ground. However, Cigar Lake decided to reinforce the entire arch of the excavation with additional support. This support consisted of thicker shotcrete, additional bolts and spiling throughout the excavation. Consultant opinions suggest that, under ideal conditions (e.g. where the rock mass is similar to what was observed but included no major discontinuities, the dimensions of the excavation geometry was as shown on the design layouts, and the ground support was installed in a timely manner and as designed), the specified ground support could have been adequate for this intersection. However, a factor of safety is compromised without additional ground control measures (such as 5 m cable bolts). Ideal conditions are not the norm. At Cigar Lake, the structural geology for this area, over-excavation of the drift and timeliness of applying ground support were all issues. On October 11, 2006 MTM drilled and blasted the 465-773 LCH intersection slash (5th round). They created a significantly larger span than the plan called for at the 465-944 DRE and 465-773 LCH intersection. MTM slashed the launch chamber using a jumbo drill and intersected unanticipated structural geology. The slashing round created a larger opening than specified in the Engineered Mine Plan. Launch chamber openings were intended to be drilled with jackleg drills, rather than a jumbo, in order to control over-excavation. There is nothing on the Engineered Mine Plan to indicate that a jackleg must be used to drill the launch chambers. Multiple driving layouts for the same area may have created some confusion over equipment requirements. Immediately prior to the ground fall, two high angled faults were mapped in the 773 LCH/XCN. At least one of these could have been identified prior to blasting the 5th round. Cigar Lake has primarily relied on core samples from diamond drill holes as an indication of what ground conditions to expect. Historically, Cigar Lake has not made geological mapping a priority as part of the development process, and it has not been Geology’s practice to do timely and sequential detailed mapping at Cigar Lake. Consultant recommendations do identify the importance of detailed geological mapping in variable ground. Design specifications planned for a span in the intersection of 7 m. The actual span generated was surveyed at more than 10 m. Consultant recommendations and the Engineered Mine Plan call for "controlled blasting techniques to be used.” Golder Associates stated, in their March 22, 2002 report, that "Controlled blasting and careful controlled excavation approaches will need to be adopted in areas of poor rock quality.” Cameco has no controlled blasting procedures in place. MTM does have a blasting procedure that addresses perimeter hole requirements. It appears that there was really no agreement on how the controlled blasting was to be done. It is uncertain whether MTM consistently used lighter charges or a trim product in the perimeter holes, in spite of an instruction on the driving layout that this be done. Following the 5th round in particular, MTM did not apply the specified ground support (bolt, screen and shotcrete) in a timely manner. At the request of MTM, an underground inspection was carried out by a Mine Engineering staff member on October 15, 2006.

of 96 16

This indicated that ground support installation was only 25% complete. An October 15, 2006 non-conformance report (issued as a result of that inspection) indicates that 106 hours had passed with only 25% of required bolts being in place, and with no shotcrete having been installed. The Engineered Mine Plan stated that "all ground support to be installed within 72 hours after blasting.” MTM indicated that the loading pocket/rock breaker was not working and that contributed to delays in mucking the area, which in turn delayed recognition of the over-excavation and installation of ground support. Records show that going beyond the 72 hour specification was typical in the 465-944 DRE. Some key personnel believed the 72 hour figure to be a guideline and not a requirement. It is MTM’s perception that Cameco prioritize and schedule their activities. From MTM’s perspective, priority in the 465-944 DRE was not as high as in other areas in the mine. On October 17, 2006 bolting was completed in the 465-773 LCH and shotcrete was being applied. Records indicate that MTM began to install shotcrete 144 hours after the 5th round was blasted. The 72 hour time period was well surpassed. On October 18, 2006 a 6th round was blasted in the 465-773 LCH to square the face. On Thursday, October 19, 2006 MTM noticed spalling of shotcrete in the area as a result of rock movement. At this time, it was observed that the east pillar of the launch chamber was undercut by approximately 1.5 m. There was visible loose rock where shotcrete fell. Also, soft ground and big blocks fell from the face in the 465-773 LCH. This was the first evidence of a large wedge requiring deep support. As there had been no prior geological mapping of the 465-773 LCH, the wedge went unmapped until this point, and therefore unsupported for a prolonged period of time. The investigation also heard that shotcrete application is not always of good quality, and limited quality assurance of shotcrete installation is done. On Friday, October 20, 2006 MTM modified the ground support that it applied for the intersection, with input from site engineering and E&P, following a meeting that took place that day. They used standard length rock bolts (2.4 m) and straps to support the undercut pillar on the east side of the 465-773 LCH and the back of the 465-944 DRE. The benched material temporarily placed for rock bolting may have concealed the actual extent to which the pillar was undercut. Current as built survey data was not available during the meeting, so those participating from corporate office did not have a full appreciation of the extent of the span of the intersection. As part of the October 20, 2006 discussion, a suggestion was made to use 5 m rock bolts in the back for the best support, but this was rejected by the Chief Mine Engineer, due to proximity to the unconformity and his perception of the risk of intersecting uncontrollable water during installation. A plan to bolt and strap the area to provide safe access to the undercut pillar was agreed upon. Once a safe access was in place, the undercut pillar and wedge were to be cable bolted to the rib to provide the necessary stability. On Saturday, October 21, 2006 the installation of straps and bolts was continued. The bolter encountered “soft” ground and indicated, in his interview, that the ground was much better when they bolted it the first time.

of 96 17

The rock bolts were producing small amounts of water. The strapping was installed at greater than 1 m intervals, but was accepted by the Senior Mine Engineer. On Sunday morning, October 22, 2006 about 10:00 hours, MTM observed more spalling of shotcrete and indications of rock movement. The Area Coordinator was contacted and went to look. He saw evidence of ground movement over a large area. There was no noticeable stress on the ground support, but lots of cracking of shotcrete in the area. He then limited access by roping off the area. The Area Coordinator relayed to the investigation that, at this point, he knew the back was coming down. It was just a question of when. The Area Coordinator requested an emergency conference call with personnel in Saskatoon to be scheduled for 13:00 hours. The Cameco and MTM representatives decided to construct a temporary bulkhead and plug the area with concrete. This was consistent with the actions taken in another part of the mine that had recently encountered deteriorating ground conditions. On October 22, 2006 sometime between 11:45 hours and 12:25 hours, a fall of ground occurred. This was accompanied by a large inflow of water, initially estimated to be approximately 340 m3/hr. At the time, the underground pumping capacity of the mine was in the order of 500 m3/hr. At 13:10 hours, a crisis team formed at Head Office and at site. The HR Superintendent was the senior person on site, and the log indicates that he asked if the East and West Doors should be prepared for closure. He also requested the procedure be available for door closure. The crisis team initially decided to install a temporary bulkhead on the 465 m level. The idea was to restrict the water flow to allow construction of a permanent concrete plug. The permanent plug was to be constructed once the water was contained. MTM used sandbags and pipes to create a dry section of drift for construction of the concrete plug. During this time, measurements indicated that the water level was decreasing in Shaft #2. According to a 14:10 hour Head Office Command Centre log entry, the General Manager communicated "make sure east and west BH doors are free and ready to go.” Efforts began to fast track emergency pumping capability. At approximately 16:00 hours on October 22, 2006 the flow rate was estimated to have increased to between 1,400 and 1,500 m3/hr. Consultants suggest that the water flow increased due to erosion of loose material in the vicinity of the unconformity. Monitoring of water levels and flow rates was conducted hourly. At this point, the net water gain in the mine was about 1000 m3/hr. Management members left Saskatoon at 19:00 hours to fly to site. At 20:50 hours, a message was received by pilots that site personnel believed the efforts should be focused on preparing to close the East and West Doors. The General Manager instructed site personnel to abandon temporary bulkhead construction and prepare the East and West Doors for closure. Priority now changed toward preparing the doors for closing. In the same time period, a visual inspection of the East and West Doors was completed to verify the condition of the gaskets. As construction of the temporary bulkhead required the services which ran through the doors, the doors could not be prepared for closure at the same time as the construction of the temporary bulkhead. In preparation for closing the doors, electrical, service water,

of 96 18

drain water and compressed air services in the Bulkhead needed to first be removed and sealed using preinstalled valves or blanks. After the General Manager gave the order to abandon temporary bulkhead construction, all efforts moved towards preparing the doors for closing. The underground crew soon discovered that the valves on the pipes through the west Bulkhead were difficult to operate due to corrosion and being covered with shotcrete. Some interviewees indicated that the valves had never been closed since they were installed. The valves are not part of the Bulkhead door PM program. Consideration was given to blanking off some pipes rather than using valves, but they experienced problems finding appropriate blanks. The sump area behind the West Door required cleaning with an excavator and air lance as it was filled with mud and water. The Area Coordinator felt no inordinate sense of urgency at this time. The Command Centre decided to preserve all the equipment they could while the doors were being prepared for closing. They salvaged equipment from the north side of the mine until the doors were ready to be closed. It is unlikely any delay was problematic with respect to the events later Monday morning. Water inflow into the mine was consistent after 16:00 hours on October 22, 2006. Once the East Door was closed, water would report to the West Door almost immediately. Thus the conditions expected during an earlier closing would be comparable to those experienced during the actual closing. Further, there was no indication at the time that the doors would not seal when finally closed. Three electricians proceeded to the 465 MCC room to begin removing electrical equipment. They were accompanied by a radiation technician. It was determined that the airborne radiation had increased at the MCC from the previous measurement of 0.3 WL to 13 WL. It was critical that the north side of the mine be swept to ensure all personnel were accounted for prior to closing the East and West Doors. Those in the Command Center developed a formal procedure to ensure all personnel were accounted for when the doors were finally closed. Five workers with SCBA carried out the mine sweep, led by a Safety Officer. All personnel were accounted for and the north side of the mine was declared clear by 02:30 hours on October 23. Guards were posted at the doors to ensure no one went into the north side after the sweep was complete. The mine sweep was described by several interviewees as professional and effective. According to the Door Closing Procedure, the 12 inch water drainage valves underneath the Bulkheads were intended to remain open until the doors were successfully closed. It required 7 hours and 25 minutes to prepare the doors for closing. This was initially thought to require about 2 hours. Much of the delay was caused by the above-mentioned Bulkhead valve issues. By 04:25 hours on October 23, 2006 all services had been removed from the Bulkheads and all valves had been closed. At that point, the General Manager gave the instruction to close the doors. At 04:58 hours, records indicate that MTM closed the East Door. Water from the inflow had been reporting to the East Door up to this point, and the water was approximately 12 inches deep in the Bulkhead when the door was closed. MTM had some minor difficulty with door squaring while closing the East Door, but they leveraged the door into place. The door formed a tight seal with little to no leakage. The investigation found that the gasket on the East Door had been replaced a year earlier, after it was found loose

of 96 19

or missing. A gasket was taken from the door on 420 m level and installed on the 480 m level East Door. The gasket adhesive, therefore, may have been in better condition on the East Door than on the West Door. At 05:10 hours, MTM attempted to close the West Door. The door was observed to be swinging nicely. No water was flowing through the door at the start of the initial attempt to close it. As the door neared closing, the MTM supervisor noticed that the door was not closing squarely. The double hinge door design made it difficult to square the doors. There is no mechanism, other than manual manipulation, for easily squaring the doors. The door closing crew then pushed the West Door open (the design weight of the door is roughly 10,000 pounds) with an LHD in order to adjust the door position. During this time, there was increasing water flow as the area behind East Door filled to the point that water began to flow to the West Door. This opening, adjustment and closing of the West Door was observed and reported to Command Center by the Mine Superintendent. No hanging gasket was observed at this time. The crew attempted to close the West Door for the second time. The water depth was now estimated at 6 inches flowing through the Bulkhead. When tightening up the come-alongs attached to the inside of the West Door, the crew noticed a section of gasket had separated and was hanging on the dry side of the West Door, creating about a 3/16 inch gap. The section of gasket was estimated by one individual to be approximately 4 feet in length, and resulted in water leakage through the door. The gasket was still attached to the door. The section of gasket, one of four around the edge of the West Door, may have been dislodged by the flowing water while closing the door. It appears the integrity of the gasket/door adhesive may have deteriorated in the bottom section of the West Door. Design and operation of the Bulkheads are such that they expose the bottom of the doors to constant water submersion. This may well have compromised the integrity of the adhesive used to attach the gasket to the door flange. The underground crew was unable to establish a water tight seal around the West Door. Initially, one visual estimate of the flow rate through the West Door was 200m3/hr. The initial plan of the underground crew was to pump concrete through the Bulkhead openings and behind the West Door. The MTM Supervisor at the door did not want to re-open the door with water building behind it. He believed aggregate would sufficiently restrict the water flow. He indicated during his interview that his idea was supported by the Mine Superintendent present at the door. The idea was communicated to the Head of the Command Centre, but was rejected. The Head of the Command Centre understood that a fully intact gasket was vital for effective sealing of the door. During a phone call at 06:16 hours, the Head of the Command Centre instructed the MTM and Cameco supervisors at the West Door to try to insert gasket material into door rather than pump concrete. This meant they needed to open the door and reinstall the gasket, or attempt to use other gasket material to complete their task. The first thing they needed to do was to source the gasket material. The MTM Supervisor estimated that the depth of water on the door was about 12 inches at this point.

of 96 20

At 06:45 hours, the Area Coordinator was sent underground to coordinate efforts. He carried gasket material with him. At this time, the dayshift crew was coming on shift and changeover of workers at the doors occurred. There were two visual flow rate estimates of 115 m3/hr and 200 m3/hr through the West Door between 06:00 and 08:00 hours. At 08:10 hours, after completing their door opening preparations, an MTM supervisor pushed the West Door open slightly using an LHD in an attempt to insert the gasket material. However, they were immediately forced to close the door due to the intense water spray. One interviewee described the pressure release behind the door as sounding like a whale blowing through its blow hole. The Area Coordinator described how the MTM supervisor operating the LHD was stung in the face by spray coming through door. Partly because the centre of the door protruded inwards, and partly because of the spray, the door closing crew decided they could not safely gain access to attempt to reinsert the gasket material. When the LHD backed away, the door slammed shut. While the Command Centre felt that an intact gasket in the door was necessary for the flow to be handled by the pumping and treating system, it turns out that the decision to force the door open at 08:10 hours to repair the gasket led to increased flow through the door. This may have been have been a result of more of the gasket separating from the door. The Area Coordinator measured the velocity and the Command Centre estimated a flow of 800 m3/hr through the West Door after the 08:10 opening. Following the door opening at 08:10 hours, a decision was made to insert burlap through the Bulkhead pipes in an attempt to seal or restrict the flow. The plan was then to grout behind the West Door and support the gasket. This plan was agreed to by the Head of the Command Centre and the Area Coordinator underground. An attempt was made to source the material for the burlap and grout on site. They had difficulty finding the required grout (there was none at Shaft #1 as expected). At roughly 09:45 hours, the cage became temporarily inoperable due to the water interfering with hoist instrumentation. Instrumentation was then bypassed to run the cage. At 09:54 hours, the cage was safely back in operation, although it could only move at 200 ft/min as opposed to its normal 600 ft/min. While nearing completion of their preparations for the burlap and grout attempt, the Head of the Command Centre instructed the Area Coordinator to open the door once again and attempt to insert the gasket. The plan to use burlap and grout was abandoned, because based upon calculated maximum flowrate through the West Door, the available pumping capacity and the remaining storage volume available underground, it was estimated that there would be insufficient time to implement the plan. The Area Coordinator was instructed to open the door a minimum of 2 feet, let the water levels equalize for a few minutes, and then attempt to insert the gasket. The Area Coordinator told the Head of the Command Centre that he did not want to open the door again. However, he was instructed by the Head of the Command Centre to complete the task. At this point, the water level behind the West Door was roughly 4 feet. The existing piping through the Bulkhead was being used to estimate the water level behind the door. At 10:35 hours, the underground crew opened the West Door at least 2 feet using an LHD. At this point, 2 ½ hours had passed since the last door opening. A large rush of water immediately came through the door from the water backed up behind it. An MTM

of 96 21

supervisor, sitting on a large tool box some distance from the Bulkhead, noticed that some key electrical pumps were going to be lost if the West Door was not immediately closed. The MTM supervisor responded to the door on a bobcat. He was up to his chest in water while sitting on the seat. The decision to force the West Door open at 10:35 hours to repair the gasket led to debris being caught in the door which allowed a significantly increased flow through the door. This time, a plastic or rubber object had been caught in the door, which made the flow rate through the door even larger. Interviewees present underground describe lots of floating material coming through the West Door when it was opened. The radiation levels (measured in WL’s) were now above 10, so workers required SCBAs for further door opening attempts, according to the site’s radiation exposure code of practice. When the Area Coordinator communicated the door status to Command Centre, all agreed that one final attempt to open the West Door, repair the seal and close the door was necessary, or the mine would be flooded. The flow rate through the West Door was now considered too high for any other option to be feasible. The Command Centre instructed the underground crew to change ventilation to the area to reduce the WL’s. However, the Area Coordinator decided to tackle the door issue prior to ventilation in order to reduce the conventional risk to the crew at the door. An MTM miner was requested by his shift boss to find 4 other workers able to wear SCBAs and to make a final attempt to repair the seal on the West Door. The MTM crew was briefed by the Area Coordinator and instructed to tie a piece of rope to the object pinched in the door, open the door very slightly and tug the object loose. Three MTM workers went to the West Door for the final door opening attempt at 11:09 hours. One operated the LHD and the other two positioned themselves at the door. The LHD operator needed to use all the force of the LHD to get the door to crack open against the water. This may have resulted in the door being pushed open farther than intended. A large rush of water came through the door, and one of the workers lost his footing and was temporarily submerged, before regaining his footing and being assisted to a nearby incline by the fourth and fifth MTM workers. Force from the flowing water exerted on the inside of the door resulted in the door being left open. This was because the high water volume flowing through the door exerted pressure on the backside of the door. Once the door was open to this extent, the LHD could not pull it closed. The LHD, which was being affected by the water, had limited traction and the operator experienced great difficulty attempting to close the door against the force being exerted by the flowing water. The remaining MTM worker at the door could not withstand the flow rate and was forced to retreat. He was struck with large debris (toolboxes, timbers, etc.) and had water coming over his shoulders. This, as well as pictures taken near this time, indicates that the water level behind the door was at least 5 feet deep. The workers recall being told in their pre-job briefing to expect a water level of roughly 2 to 2 ½ feet. In attempting to pull the door closed, the LHD broke the ¼ inch wire rope it was using. The LHD operator shut off the LHD, jumped from the machine, and was helped to the nearby incline by the others. The water was described as being extremely cold.

of 96 22

At this point, the Area Coordinator, waiting with others near the #1 Shaft, consulted with the miners and decided to evacuate the mine. The Area Coordinator reported the situation to the Command Centre at 11:14 hours. The General Manager agreed with his decision to evacuate the mine. At this point, workers reported the water being 3 to 4 feet deep at the cage level doors and difficult to walk in. The Area Coordinator called for the cage. However, because there was too much water flowing into the shaft on the 480 level, the hoist operator could not lower the cage into the normal position at that level. The hoist operator staged the cage just above the 480 level access and the workers used a ladder to access the cage. With an approximately 1 foot gap to get from the ladder into the cage, extra care was required in entering the cage. A total of 21 workers on the 480 level climbed up the ladder into the cage. Audible communications between the cage and the hoist operator were maintained at all times, although visual communications to the hoist room were lost just prior to the signal to go up. The cage stopped at the 420 level to pick up 3 more workers, who had been monitoring the pumping station. The total number of workers on the final cage exceeded the posted occupancy limit. In addition, a skip full of water was hanging below the cage. The weight of both, taken together, was well within the cage hoisting capacity. Several interviewees felt that 24 people underground at the final door opening was excessive. However, a decision was made to keep the cage near the 420 level and take everyone at once, rather than making two trips at a reduced cage speed. The cage reached surface at approximately 11:30 hours. The person in authority indicated that there was no way of knowing, with certainty, if everyone had been accounted for until a count of tags on surface compared to the numbers of people on the cage was complete. However it was determined that ample time was available to return the cage to the 480 level if required. The miners, soaked from their efforts, were instructed to tag out and hand in all of their radiation monitoring devices. Everyone was accounted for, a radiation monitoring device was placed at the shaft collar, and services were shut off to the mine.

of 96 23

4.0 CAUSAL FACTORS AND SUPPORTING INFORMATION

4.1 Causal Factor #1 – Construction on the 465-944 DRE was started prior to having adequate emergency water pumping and treatment systems in place

Discussion of Causal Factor Cigar Lake management was clearly aware they did not have the emergency water pumping and treatment capacity to handle a serious inflow into the mine during development of the 465-944 DRE. Construction was underway to upgrade the emergency pumping and water treatment plant capacity. Members of the management team interviewed had not been concerned about the possibility of a large water inflow during advancement of the 465-944 DRE. They indicated that the ground on the 465 level was much better on the south access drift than on the north access drift. They all pointed out that Cigar Lake did not have any previous problems in the 465-944 DRE when it was advanced prior to 1999. Historical geological information provided Cigar Lake with confidence that the area could be successfully mined with the proposed approach. The consultants are in agreement that the 465-944 DRE could have been driven without a fall of ground, accompanied by a serious water inflow. However, as discussed in later Causal Factors, to achieve that result, tight controls on over-excavation and ground support would be necessary. In reality, these controls were not implemented. In hindsight, one can argue that a higher level of concern about the potential fall of ground and water inflow related risks associated with the 465-944 DRE was appropriate. Basis for Causal Factor • There were 75 m of previous development on the 465-944 DRE. This was done in the

1990s. • Development of the 465-743 XCN was halted by a small inflow and collapse of

ground in 1999. The consultants are in agreement that there is no direct relationship between the 1999 and 2006 inflows. More specifically, the structural geologist and geotechnical consultants were asked to comment on any relationship between the 1999 inflow, the Shaft #2 inflow, the clarifier ground instability, and the October 2006 inflow. None of the consultants identified any common geological structures connecting the incidents. No instrumentally recorded seismic events occurred at or around the time of any of the incidents.

• Consultants later confirmed that the approximate nominal elevation of the 465-DRE/773-XCN back was 1,032 to 1,034 m. The unconformity elevation is nominally 1,042 m. That indicates the unconformity was somewhere between 8 to 10 m from the back of the 465-944 DRE.

• The ground to be developed in the 465-944 DRE was generally accepted by Cigar Lake staff as classification RM 2/3. The RM 2/3 classification has been confirmed by some consultants used in this investigation.

of 96 24

• The rock type in the 465-944 DRE was classified from diamond drill hole related geotechnical analysis. This was done both from the surface and from the 480 level.

• Historical consultant reports relating to Cigar Lake predicted, and the McArthur River inflow demonstrated, that water inflow could be much higher than originally anticipated at Cigar Lake, thus the plan was to increase the emergency pumping and treatment capacity at Cigar Lake.

• In February, 2006, a corporate audit of water inflow potential was completed by E&P. This audit was carried out at Rabbit Lake, McArthur River and Cigar Lake. It had been requested by Cameco’s VP-Mining as a result of the 2003 McArthur River water inflow. In the Cigar Lake audit findings, recommendations were made to take special precautions for mining 465 level access drifts. The investigation found no formal dispositioning of the February, 2006 audit recommendations on water risks at Cigar Lake. Site management may not have appreciated the warnings, as the audit report distribution was limited and management believed the report applied to post construction, not development.

• The advancement of the 465-944 DRE was on the Cigar Lake General Arrangement. The investigation has been unable to identify if there was additional rationale for recommencing development of the 465-944 DRE.

• Cigar Lake’s Engineered Mine Plan called for stopping development of the 465-944 DRE at the 10790 easting. Further corehole drilling was planned prior to proceeding with the 465-944 DRE development. Historical corehole data indicated that the ground beyond the 10790 easting was getting worse (i.e. toward RM 2 ground from RM 2/3).

• Cigar Lake management personnel were comfortable with the 10 m pillar between the 465-944 DRE and the unconformity. They did not recognize it as a significant risk.

• Prior to recommencing advancement on the 465-944 DRE, probe and grout holes were drilled. These did not reveal any significant water concerns.

Interview Data • Recognizing that individual opinions and beliefs cannot, by themselves, be taken as

being entirely factual, the investigation found some consistency in interviewee responses. Several interviewees commented on the rationale for going ahead as follows:

- A senior member of the Cigar Lake management team stated that the reason for continuing the development of the 944 drift at this time was to gain access to a raise further down the drift. Others questioned the validity of that assertion.

- According to another senior Cigar Lake individual, the issue of driving the 944 drift prior to having emergency pumping in place was never raised.

- Two relatively senior Cameco individuals interviewed expressed surprise to hear of construction of the 465-944 DRE without additional pumping capacity being in place, since water inflow was pinpointed as a high risk area.

- The thinking among the decision makers at Cigar Lake was consistent. Several interviewees made comments to the effect that we had driven in 944

of 96 25

before and didn’t have any major problems. We felt we could do it again. Regarding the 465 level, we have had past development in the area so we were confident in the integrity of the area.

- MTM miners working in the drift also believed there was no problem. They felt the ground was good and they were also surprised by the change in ground conditions.

- The risk of significant water inflow into the 465-944 DRE was not fully appreciated by all key individuals involved in advancing the drift. A couple of individuals interviewed made statements that they never thought about water inflow as a potential result of a fall of ground on the 465 level. There was also a lack of awareness from the MTM interviewees regarding the distance to the unconformity.

4.2 Causal Factor #2 – The Engineered Mine Plan for this intersection was not sufficiently conservative given the geology encountered, the existing resources and conflicting priorities at Cigar Lake

Discussion of Causal Factor Consultants suggest that, under ideal conditions of use, the specified ground support could have been adequate for this intersection. However, Golder Associates believes there was an insufficient margin of safety without additional ground support measures (such as 5 m cable bolts). Itasca believes the designed level of support was reasonable as a starting point – to be modified if adverse conditions were encountered during development. Although the Engineered Mine Plan for the intersection may have been appropriate under ideal conditions, ideal conditions are not the norm. To compensate, the execution of the plan must be strictly enforced, including prioritization of resources to ensure control of excavation, timeliness of ground support and identification of adverse geology. Causal Factors below will describe that effective controls were not in place to ensure these other key elements were addressed. Basis for Causal Factor Consultant Opinions • On March 22, 2002, a report was issued by Golder Associates. The purpose of this

report was to validate the mine design. Two recommendations in particular were made that proved relevant to the October 22, 2006 fall of ground. Golder Associates stated in their report that "controlled blasting and careful controlled excavation approaches will need to be adopted in areas of poor rock quality.” They also recommended using cable bolts in all intersections.

• In its March 22, 2002 review, Golder Associates stated that "actual support should be based on the specific conditions encountered and the observations made.”

of 96 26

• In a March 8, 2002 review, Golder Associates had recommended the use of cable bolts in intersections greater than 8 m. However, Golder Associates has confirmed that these recommendations apply only to permanent infrastructure intersections, and not to mine development.

• PBQD provided geotechnical recommendations for the Cigar Lake mine design in the late 1990’s. They recommended longer support in the equivalent of RM 2/3 ground (Type B) where discrete wedges are mapped. The area where the fall of ground occurred was classified as RM 2/3 ground and at the time the ground support was being designed for this area discrete wedges were not identified. PBQD independently calculated (their calculation was subsequently confirmed by a Cameco engineer) the possible stresses induced by ground freezing (about 50 m distant) from the inflow site. The calculation established that the magnitude of the induced stress change was insufficient to be a significant contributing factor to the inflow.

• In its review of Golder Associates and PBQD geotechnical reports, Itasca comes to the following conclusion: "Several other reports contributed by Parsons Brinckerhoff and Golder Associates between the late 1990s and 2006 have made suggestions on the support to be used for various excavations. These recommendations are not all consistent with each other. Cameco staff were thus placed in the position of choosing between the various suggestions to establish an appropriate level of support for the various excavations. Further, many of the reports stated that the actual conditions should be established on site during development, and the various support suggestions were qualified as being ‘generic in nature’ and ‘suitable for costing.’ Although the various reports quoted ‘typical’ support for development, they were less specific about the support of intersection, and, in most cases, simply suggested that longer bolts or cable bolts should be used for intersections.”

• Consultant opinions suggest that, under ideal conditions, the specified ground support could have been adequate for this intersection. However, Golder Associates believes there was an insufficient margin of safety without additional ground support measures (such as 5 m cable bolts). Itasca believes the designed level of support was reasonable as a starting point – to be modified if adverse conditions were encountered during development.

• Itasca refers to the “1/3 of span rule,” which is the commonly adopted starting point for choosing support length. Using this commonly accepted practice, one would arrive at a length of 2.4 m for a 7 m intersection, which is consistent with the support specified on the Engineered Mine Plan. However, another senior consultant emphasizes that this “rule of thumb” is a starting point, but that it is not appropriate for the final design of intersections.

• It is widely recognized that ideal conditions are not the norm in mining and certainly not at Cigar Lake, where the structural geology for this area, over-excavation of the drift and timeliness of applying ground support were all issues.

Interview Data • The fault structure that showed up in the 465-944 DRE/465-773 LCH intersection

was not mapped earlier. Cameco did not anticipate the geological structures encountered, even though Cigar Lake’s consultants had stated they needed to be prepared for the unexpected.

of 96 27

• Having indicated that the geological features encountered were not forecast, one Cigar Lake technical consultant stated that it is not uncommon to encounter these types of structures at Cigar Lake.

• The investigation found no evidence that Cigar Lake formally dispositioned Golder Associates’ recommendations on cable bolting all intersections.

• The Engineered Mine Plan made no reference to extra support or alternative support for intersections, nor does it make any reference to 5 m cable bolts. However, Cigar Lake decided to reinforce the entire arch of the excavation with additional support. This support consisted of thicker shotcrete, additional bolts and spiling throughout the excavation.

• Cigar Lake decision makers indicated they rejected the 5 m cable bolt recommendation from the consultants due to the water inflow related risk of intersecting the unconformity. These individuals were very sensitive to being in close proximity to the unconformity, and felt 5 m cable bolts were not a realistic option.

4.3 Causal Factor #3 – A significantly larger span than the Engineered Mine Plan called for was excavated at the 465-944 DRE and 465-773 LCH intersection

Discussion of Causal Factor Golder Associates, in their assessment of the ground fall, summarized this Causal Factor quite effectively. They stated "The 465-944 DRE was excavated through the location of the intersection with 465-773 LCH before beginning any development of the launch chamber itself. After developing through an intersection, Cameco’s guidelines for the excavation of launch chamber rounds are understood to require the use of jackleg drills and controlled blasting, to maintain the profile of the cross-cut intersections. The requirement to use a jackleg was not explicitly identified in the “driving layout” for 465-773 LCH, although it is understood that this was considered by Cameco to be standard practice. In practice, MTM crews took the first round of 465-773 LCH (and possibly previous initial launch chamber rounds) as a slash with a jumbo. By taking this slash with a jumbo, the west corner of the launch chamber cross-cut (NW corner of the intersection) was blasted outside the design profile. There were three main reasons for MTM to use this approach: • The jumbo was too large to drill holes perpendicular to the 5.1 m wide 465-944 DRE

drift. • The mucking equipment that MTM had available was too large to muck the first

round if a square corner was created. • The MDS machine could be moved more easily into the launch chamber if the corner

overbroke beyond the design lines. The orientation of the fanned blastholes used to take the first round of the 465-773 LCH would also provide very poor control of blast damage on the east rib of the 465-773 LCH. The wall would be formed by the bootleg of the fan holes, which are drilled almost

of 96 28

perpendicular to the rib, so the controlled blasting specified by Cameco (using Trimtex or equivalent in perimeter holes) could not be applied. In the case of the 465-773 LCH, the normal overbreak caused by this practice was exacerbated by the presence of the north-dipping structure that intersected the corner. The blast overbroke to the structure, resulting in the removal of as much as one meter of additional rock from the corner. The small MDS turnout excavated in the south rib of the 465-944 DRE opposite the launch chamber was drilled and blasted as part of the drift development rounds rather than being mined after drilling past it. This also resulted in overbreak because of limitations of the orientation at which blast holes could be drilled. The blasting practice on both the north and south sides of the intersection lead to overbreak in the intersection and an increase in the span of at least 3 m beyond its design.” The following Figures were prepared by Golder Associates and illustrate the two drilling techniques. The first Figure represents what the pattern would have looked like with a jackleg drill. The second Figure represents what was actually done in drilling the 5th round, and illustrates the extent of the over-excavation experienced, partly due to the method of drilling and blasting used.

of 96 29

Geological mapping is another control that could have been used during the 465-944 DRE advancement, but was not. Immediately prior to the ground fall, two high angled faults were mapped in the 773 LCH/XCN. At that point, most interviewees and some consultants agreed that it was too late to do anything to prevent the fall of ground. If geological mapping had been part of the development process at Cigar Lake, at least one of these geological structures should have been identified prior to MTM blasting the 5th round on October 11, 2006 and the 6th round on October 18, 2006. Precautions quite likely would have then been taken in blasting the 5th and the 6th round. These precautions may have kept the span within plan specifications, and likely would have ensured more emphasis on timely ground support. Although Golder Associates had previously detailed the importance of doing geological mapping prior to development, historically, Cigar Lake has not made geological mapping a priority as part of the development process, and it has not been Geology’s practice to do timely and sequential detailed mapping at Cigar Lake. Instead, Cigar Lake has primarily relied on core samples from diamond drill holes for information on what ground conditions to expect.

of 96 30

The following Figure provides some excellent detail on the geological structures present at the intersection where the fall of ground occurred.

Basis for Causal Factor Consultant Opinions • Consultant recommendations identify the importance of detailed geological mapping. • Consultants recommended and the Engineered Mine Plan called for controlled

blasting techniques to be used. However, Cameco has no controlled blasting procedures in place. MTM does have a blasting procedure that addresses perimeter hole requirements. It appears that there was really no agreement on how the controlled blasting was to be done. It is uncertain whether MTM consistently used lighter charges or a trim product in the perimeter holes, in spite of an instruction to use controlled blasting on the driving layout;

• Immediately prior to the ground fall, two high angled faults were mapped in the 773 LCH/XCN. If geological mapping had been done, at least one of these should have been identified prior to blasting the 5th round on October 11, 2006 and the 6th round on October 18, 2006.

• The Engineered Mine Plan called for a span of 7 m. The actual span was surveyed at approximately 10 m.

• The slash (the 5th round on October 11, 2006) was drilled with the Jumbo (approx 4.5 m taken). At least one individual from Cigar Lake Mine Engineering indicated the intent was that the breakout or 1st round into launch chambers be drilled using a jackleg drill, not a jumbo drill. However, there is nothing on the driving layout given to MTM that indicates a requirement to use a jackleg drill for launch chambers.

of 96 31

• The bottom half of the pillar broke to a fault (i.e a geological structure). • The undercut pillar was fractured quite badly. Also, large pieces were described as

coming off two walls and the cross cut face of the launch chamber after the 6th round was taken on October 18, 2006.

• When a teleconference was held on Friday, October 20, 2006 to discuss problems in the 465-944 DRE, the personnel in Saskatoon were not fully appreciative of the actual span of the intersection. The personnel at site had a sketch of the area and were appreciative of the actual span. Had the individuals in the corporate office known the span of the intersection, it may have affected the outcome of the conference call. In any event, some consultants suggest that it may have been too late to prevent the fall of ground at that point.

• It is clear from the organization chart that the communication route from the Cameco General Manager to the MTM miners is lengthy. This may have contributed to a lack of awareness of the importance of the design specifications.

Interview Data • Again, recognizing that individual opinions and beliefs cannot, by themselves, be

taken as being entirely factual, interviewees had a great deal to say in this area. Most of it is consistent with respect to helping to understand the history of what happened:

- One individual stated quite firmly that, historically, site Construction did not appreciate site Geology slowing development down by mapping drifts.

- One individual stated that site Geology is not aggressive in mapping drifts, because their priority is to be involved in freeze hole drilling, and this is resource challenging.

- At least two individuals interviewed indicated that geological mapping of the 944 drift could not be done, since it was shotcreted before the mapping could be completed.

- At Cigar Lake, going underground was described by one individual as being dictated by cage runs. There is 2 ½ hours between cage runs, and people are only transported at certain hours. This limits what one can do.

- The MTM miners and their supervisor indicated in interviews that they had no knowledge that they were close to an unconformity. Had they been aware of the distance to the unconformity, they may have taken extra precautions.

- The investigation heard ‘there is too much MTM versus Cameco’ and ‘they do not work well as a team;’ however, others indicated the working relationship between Cameco and MTM was a cooperative one.

- Several people interviewed stated there is no question that there was over-excavation on the back. This means the distance to the unconformity was less than 10 m. Several interviewees indicated that Cigar Lake has significant problems with over-excavation (from 1 ft to 1 m). The 465-944 DRE was described as being 1.5 m too high on the back, and that was perceived to be significant.

of 96 32

- It is generally recognized that the ‘actual dimensions’ are routinely outside the ‘planned dimensions’. This was only of moderate concern to those interviewed.

- Mine Engineering and site Construction are responsible for ensuring that MTM stays within the specifications of the Engineered Mine Plan.

- Several interviewees believe MTM was not using good blasting technique, which contributes to over-excavation. They indicated that a sawtooth back (as present in the 465-944 DRE) is a sign of an inexperienced jumbo operator.

- Two MTM miners stated that everything was blasted with ‘Amex’. They expressed their opinion that Amex hits 4 ft into the rock. They suggested that one needs to blast the perimeter holes with “magna split” (e.g. low compression powder).

- One Cameco engineer who, on Friday, October 20, 2006, visited the intersection where the ground came down on October 22, 2006, had no idea they were so close to the unconformity. However, there was no question in this individual’s mind that MTM had exceeded the critical span in this intersection.

- Several personnel interviewed suggested that Mine Engineering and site Geology needed a greater presence and authority underground.

- One senior Cigar Lake interviewee felt that not recognizing ‘sloughage’ is the big issue. This individual questioned the experience of mine engineers and their ability to see the risk of pillar sloughage.

- It appears that MTM was unaware of the jackleg drill requirements for slashing the launch chamber.

of 96 33

4.4 Causal Factor #4 – The specified ground support was not applied in a timely manner

Discussion of Causal Factor Not applying the required ground support in a timely manner was the “final straw” for the 465-944 DRE. Even with the geology encountered and the large span, the fall of ground and subsequent inflow of water may have been prevented if the ground support had been applied in a timely manner. In addition, in the opinion of a senior consultant, 72 hours, as specified by the Engineered Mine Plan, is much too long a time to complete the application of ground support in excavations such as these. Because it was considered impractical for MTM to install ground support in a more timely manner, a specification of 72 hours for the ground support to be in place for the 465-944 DRE was negotiated and adopted. A non-conformance report dated October 15, 2006 indicates that 106 hours had passed after the 5th round had been taken, only 25% of required bolts were in place, and no shotcrete had been applied. The Engineered Mine Plan specifies complete ground support is to be in place within 72 hours. Upon reviewing data provided by Cigar Lake, it is clear that going beyond the 72 hour specification was typical in the 465-944 DRE. The 72 hour specification for ground support was only recently added to the driving layouts for the 465 m level. Mine Engineering’s intent was that the information on the driving layouts served as a requirement, not just as a guideline. The investigation found several factors related to the ground support not being applied in a timely manner. Two key Cameco supervisors did not consider that placement of ground support within 72 hours was a ‘hard and fast rule’. They thought it was more of a guideline. Ventilation was generally agreed to be a big factor restricting mucking and shotcreting - two key elements of ground support. It was generally believed that ventilation essentially drove the underground development, and that MTM was constantly reacting to situations, and not acting proactively. One other important factor, according to a couple of interviewees, was the fact that there was only one MTM development crew, and this crew had conflicting priorities. Basis for Causal Factor • A non-conformance report dated October 15, 2006 indicates that 106 hours had

passed with only 25% of required bolts in place and no shotcrete having been applied. The Engineered Mine Plan specifies that complete ground support is to be in place within 72 hours.

• Upon reviewing data provided by Cigar Lake, it is clear that going beyond the 72 hour specification was typical in the 465-944 DRE.

of 96 34

• The 72 hour requirement for ground support was only recently added to the driving layouts for the 465 m level.

• Mine Engineering’s intent was that the information on the driving layouts served as requirements, not guidelines.

• Some key personnel understood that the 72 hour specification for ensuring that ground support was in place was a guideline, not a requirement. Others clearly saw the 72 hour figure as a requirement.

• MTM indicated that some safety bolts were installed in the area where the 465-773 LCH was to be slashed. They did not install the same grid as required on the driving layouts. According to MTM, this is consistent within the mining industry.

• On Tuesday, October 17, 2006, an MTM supervisor issued an RFI to Mine Engineering, requesting that an underground inspection be performed. This resulted in a ground support non-conformance report. While ground support in that drift had routinely been in non-conformance, only one non-conformance report had been generated relating to ground support for the 465-944 DRE development.

• As early as 2005, internal corporate audits routinely communicated the importance of timely ground support to Cigar Lake.

Interview Data • The investigation found that many individuals were concerned with this Causal

Factor. Once again, recognizing these are opinions and beliefs (and not fact), what was heard helps to explain how this Causal Factor came to exist:

- It is MTM’s perception that Cameco prioritizes and drives MTM’s activities. From the perspective of the MTM personnel interviewed, priority in the 465-944 DRE was not very high. They indicated that they worked in the 465-944 DRE when there was nothing else to do. They did what Cameco requested them to do.

- Some Cameco Cigar Lake personnel felt that site Construction, and not Mine Engineering, was driving the schedule of what was to be done underground. In their opinion, Mine Engineering were marginalized and site Construction largely determined what work was done.

- One Cameco supervisor stated that Cigar Lake had a 72 hour standard on ground support, and that he expected a non-conformance report if it went longer than that. The investigation only found one non-conformance report issued on the 465-944 DRE, and that came as a result of an MTM request to inspect the drift.

- Prior to the arrival of the new Cigar Lake Construction Manager, development plans were done day by day. There was no high level (longer term) schedule. He established a three day rolling plan.

- A few experienced interviewees indicated that it was typical for ground support to be delayed at Cigar Lake.

- Virtually everyone interviewed described the Cigar Lake ventilation as very poor and as impacting, in a negative way, mucking, shotcreting and everything else requiring powered equipment.

of 96 35

- It is widely believed by individuals on site and in the corporate office that ventilation significantly influenced the underground development at Cigar Lake, and that MTM was constantly reacting to the ventilation limitations at any given time.

- An important factor influencing the timing of ground support, according to a few interviewees, was the fact that there was only one MTM development crew, and several places underground where work needed to be done.

- One of the MTM supervisors indicated that a great deal of information is passed down from Cameco to and through MTM. His message was that it was challenging for MTM to effectively deal with all of the information. Others indicated it wasn’t a problem.

- One senior Cameco interviewee felt there is an issue with the drawing standard at Cigar Lake, and that this creates inconsistencies. For example, there are drift drawings and launch chamber drawings which define overlapping requirements for the area in question, which potentially could have created confusion.

- Two interviewees, who stated that they came from an organization where shotcrete standards are high, suggested that there may be a problem with the quality of application of shotcrete at Cigar Lake. Specifically, they felt that the shotcrete is often just painted on the walls and not properly applied. The interviewees stated that if the shotcrete is just applied on the back and not on the side walls, it does not provide the intended support.

- The MTM miners interviewed, however, felt that shotcreting was fine. They indicated that "the guys take pride in their work.”

- A few interviewees suggested there are many inexperienced MTM miners and some inexperienced supervisors. These same interviewees pointed out, however, that MTM’s senior staff on site (Mine Captain and up) was extremely experienced, knowledgeable and competent.

- A few individuals interviewed offered their viewpoint that the Area Coordinators are driven by “cubic metres blasted”, as this is a unit that is seen to be valued.

- A senior Cameco Cigar Lake individual believes there were too many junior people, both with MTM and Cameco, and that this is the main reason the ground support was not put in place in a timely manner.

- A number of individuals indicated that at other mines, the Mine General Foremen would walk into a heading and shut it down if ground support was not what it needed to be. According to these individuals, that did not happen at Cigar Lake.

- The miners involved in the 465-944 DRE pointed out a three day delay in mucking following the 5th round on October 11, 2006. They stated the opinion that if you leave a great deal of open ground for three days, you are going to have problems. According to the miners, the reason the area didn't get mucked was because there were other priorities in other spots.

of 96 36

- According to the MTM miners, the MTM bosses listen to whatever Cameco wants done, and then they do it.

- The miners who were interviewed described a big "got to get it done" time factor all the time. According to them, this is because they are not organized, and are always looking for gear. In their opinion, this is totally an MTM problem.

- One interviewee pointed out that after August 1, 2006, bolting, screening and shotcreting was better, as Cameco went to a 'time and materials' contract with MTM.

- One senior Cameco person, when asked about ground support, suggested that "MTM generally do pretty well but from time to time, they need a pep talk.”

- One individual interviewed stated that it required weeks and a real fight in order to get areas shotcreted in the mine. That individual pointed out that you do not have any area ground support until it is shotcreted. In this individual’s estimation, some shotcrete application lagged for months.

- One individual offered an opinion that there were very few people at Cigar Lake who get uptight about ground control lagging behind.

- A few Cameco personnel indicated that no concerns regarding ground control ever came back to Cameco from MTM.

- The investigation heard that Cigar Lake does not have an effective protocol for reporting unusual ground occurrences, and that a Work Instruction titled “Reporting Unusual Ground Occurrences” has been awaiting approval for 6 months.

- One interviewee stated that "MTM generally do not report anything! But they reported the problem with the ground leading up to October 22nd. Therefore, MTM must have seen something pretty bad.”

- Two Cameco individuals at Cigar Lake stated that we need to stop doing 'ground support' and start doing 'ground control'. They described ‘ground support’ as the day-to-day installation of shotcrete, bolts, etc. and ‘ground control’ as the overall program that governs ground support, which would encompass critical span, controlled blasting, policies for ground support timeliness, etc. These individuals suggested that there is no immediacy or urgency about doing ‘ground control.’

Cameco Cigar Lake personnel also commented on the quality of ground support installation processes. One knowledgeable individual from Cigar Lake was particularly critical of support installation processes. As an example, this person described bolts being put into rock with no resin for 3 feet, as opposed to the resin being present right to the collar as is the intent. There are also limited quality checks on the shotcrete being put up by MTM.

of 96 37

4.5 Causal Factor #5 – The initial attempt to close the West Door was not completed in dry conditions as specified in the design

Discussion of Causal Factor During the first closure attempt for the large 14 foot diameter, 10,000 pound (plus) West Door, the MTM workers realized the gasket was not square to the stress transfer cylinder flange. If they were to proceed, one side of the gasket would have contacted the stress transfer cylinder before the other, and the workers felt that this may have caused damage to the gasket. They immediately decided to push the door open, and to adjust it on its double hinges until it was square. As with the East Door, the West Door was intended to be closed without the presence of water in, or flowing through, the bridge pit. The door was intended to be swung by hand into alignment with (and square to) the stress transfer cylinder. It is clear the intent of the door design group, CESL, was to keep the door clean and dry. During emergency flow conditions, a sump pump was intended to help prevent the water level in the bridge pit from rising too quickly, giving personnel more time to close the door under dry conditions. While they were squaring up the West Door and preparing for their second closure attempt, water began to flow through that Door. The Bulkhead design included a 12 inch diameter pipe running through the Bulkhead, below road level. Under emergency conditions, the pipe was intended to be open, and was to be used to divert inflowing water away from the door, allowing the bridge pit to remain dry for as long as possible. A valve was installed in each of the drain pipes at the south end of the Bulkhead. However, the 12 inch drain pipe valve was closed prior to swinging the West Door closed. This meant that the water flowed through the Bulkhead earlier than it otherwise would have, which may well have contributed to the gasket coming loose from the West Door. If the West Door had been square during the first closure attempt, or if the water had been delayed in flowing through the Bulkhead, the workers would, in all probability, have been able to seal the West Door with its entire gasket intact. Side and top view general arrangement diagrams of the East and West Doors and their gasket details appear in the following 3 Figures. An actual photograph of the West Door is also included.

of 96 38

Typical Bulkhead General Arrangement – Side View

Typical Bulkhead General Arrangement – Top View

Bulkhead Door Gasket Detail (Not to Scale)

of 96 39

Stress Transfer Cylinder

Gasket

Bulkhead Door

Adhesive

Figure The 480 West Door. Shows tugger, bridge, bridge shackle points, blanked pipes, and top right door anchor point.

Tugger

Bridge

Bridge Shackle Points

Blanked Pipes

Top Right Door Anchor Point

of 96 40

Basis for Causal Factor • The East and West Doors were installed in 1991. The doors are double-hinged, which

can make it difficult to square them during closing. • The West Door is 14 feet in diameter, weighing approximately 10,000 pounds. The

East Door is a 12 foot diameter door. • There is no mechanism, other than manual manipulation, for squaring the doors when

they are being closed. • Available maintenance records indicate that the last time the West Door was fully

closed as part of its PM program was in 2004. Other information suggests that the West Door may have been closed in January, 2006.

• The doors will not effectively seal unless they are reasonably aligned (i.e. square to the Bulkhead) when closed.

• On the 1st attempt to close the West Door at 05:10 hours, there was water in the sump on the north side, but no water flowing through the Bulkhead. However, when it became clear that the door was not square to the Bulkhead, and that MTM needed to push it open to adjust it, water began to flow through the door. It was estimated that the water level behind the door was about 1 foot when the door was closed the 2nd time.

• The weight of the door and the double hinge makes it difficult to square by hand from inside the stress transfer cylinder before closing the door. That is, it can be difficult to get the door square to the opening of the Bulkhead. The MTM crew was about 1.5 inches off in aligning the West Door the first time they attempted to close it. This meant that the gasket may have been damaged when it contacted the transfer cylinder.

• A maintenance record dated November 30, 1991 states ‘Even after greasing all bearings the door is difficult to move compared with the ease with which it moved when new.’

• When they found the West Door was not square in the 1st closure attempt, MTM then bumped the door open just enough to square it up. One of the MTM workers said "we're lined up now" and it was pulled closed. Estimates ranged from 5 to 30 minutes to reopen, square and close the door.

• An MTM supervisor with significant experience with the Bulkhead doors was brought underground during the period leading up to the door closing.

• Procedures/instructions for closing the 420L and 480L Bulkhead doors are described in the Cameco document “Underground Water Control Bulkhead Door Closing”, QMS document number 199-001-01. Two versions of this document were obtained. Revision 0 indicates it was issued April 11, 2005. Revision 2 indicates it was issued February 22, 2006. During an interview on February 8, 2007, the Cameco individual responsible for the procedure at Cigar Lake advised that Revision 0 of the Underground Water Control Bulkhead Door Closing document was in effect at the time of the inflow.

• The format used for the Underground Water Control Bulkhead Door Closing documents is primarily paragraph text accompanied by coloured photos.

of 96 41

• The “CLMC Bulkhead Closing Procedure” document prepared by one of the CESL designers, dated June 12, 1990, is similar in content and appears to be the basis for the Underground Water Control Bulkhead Door Closing document. No other documented procedures or work instructions related to the door closing process were found.

• The Bulkhead designs included a 12 inch diameter pipe running through the Bulkhead, below the drift floor level. Under non-emergency conditions, this pipe was intended to drain away any water that had been diverted into the drainage ditch by the cross sloped drift. Under emergency conditions, the pipe could be used to divert inflowing water away from the door to allow the bridge pit to remain dry for as long as possible. A valve was installed in each of the drain pipes at the south end of each Bulkhead.

• All of the valves on the Bulkheads were rusted, making it difficult to free up and close the valves.

• The investigation determined the 12 inch drain pipe valves were closed prior to swinging the doors closed.

• Cigar Lake’s Underground Water Control Bulkhead Door Closing documents (Rev 0 and Rev 2) include, in the sections for closing the 480L doors, the statement: "The next step is to close the valves around the door (see Figure 5).” The Procedure does not explicitly state that the 12 inch valve needs to remain open until the door is closed, nor did it specify that the doors were intended to be closed in dry conditions.

• The door design was such that the electrical power to the pumps behind the door needed to be disconnected prior to closing the door. Thus, the crew had no means of keeping the water down once it reported to the door.

Interview Data • The investigation found that many individuals had comments relevant to this Causal

Factor. Once again, recognizing these are opinions and beliefs (and not fact), those comments help to explain this Causal Factor:

- In an interview with Cameco and MTM staff at Cigar Lake on February 1, 2007, they advised that, during their PM for the doors, it was never possible for one person to close the door, and that the door always had to be pushed closed, not pulled closed, as described in the Underground Water Control Bulkhead Door Closing documents. At least two people would typically be required to close the door by hand.

- During an interview with the MTM individual who carried out several PMs on the doors over the years, he stated that the doors were always difficult to square during closing procedures. The individual in question was an employee of CLMC in 1990-91 when the doors were originally installed.

- The MTM individual who was asked to supervise closing the West Door indicated that he had no knowledge of the Underground Water Control Bulkhead Door Closing document prior to be asked to go underground on October 22, 2006.

of 96 42

- In an interview with the Cigar Lake Cameco individual responsible for the Door Closing Procedure, he advised that classroom training on the Underground Water Control Bulkhead Door Closing document issued April 11, 2005 was provided to personnel. When asked about training records, this individual noted that there may not be records available.

- One of the most experienced individuals interviewed stated that ‘there was no good understanding of how to actually close the doors. The valves on the Bulkheads had never been closed or tested’ to this individual’s knowledge.

- One individual suggested that, in hindsight, they should have sandbagged the West Door to buy some time without water, when closing, in case they had problems. This individual indicated that you could sandbag in a way that you would have no water at either the East or the West Door for a short period of time.

- One interviewee, who was directly involved in closing the doors, indicated that once they were able to move the 12 inch valve on the West Door and get it closed, they were not going to move it again. This individual was very familiar with the PM program on the doors, and stated that the valves were not part of that program. He suspected that the 12 inch valve on the West Door may not have been closed in years. Also, the 2 top valves were described as being covered in shotcrete.

4.6 Causal Factor #6 – Upon adjusting and closing the West Door, a section of gasket separated from the door flange, resulting in water flow through the door

Discussion of Causal Factor As with the East Door, the West Door was intended to be closed without the presence of water in, or flowing through, the bridge pit. It was intended to be swung by hand into alignment with (and square to) the stress transfer cylinder opening. Ideally, the gasket would remain in position in its groove during the door closing and pre-compression cinching activities, and would therefore provide a uniform initial seal around the perimeter of the door. Lastly, the gasket would remain in its groove during subsequent compression, due to the force of the rising water level. In an emergency situation, when one or more of these conditions are not met, the ability of a seal to be established and maintained is less assured. At some point during the door closing or pre-compression cinching activities, a section of the gasket separated from the West Door, and became caught between the door flange and the stress transfer cylinder flange. This prevented an initial gasket-flange seal from being established, and resulted in a leak. The gasket/door integrity may have deteriorated in the bottom section of the West Door in the time period leading up to the inflow. While the exact mechanism of the gasket coming loose is still unclear, it may be a combination of:

• ineffective or incorrect gasket adhesive;

of 96 43

• deterioration of gasket adhesive because of the effects of moisture, as the bottom of the door was in a muck-filled sump;

• grease on the gasket causing the gasket to “shift” out of its groove on tightening; • unequal tightening pressure on the gasket may have contributed to the shifting of

the gasket (MTM started tightening at the bottom of the door); and • water flowing past the gasket serving to break it loose;

Basis for Causal Factor • It is clear that the intent of the door design group, CESL, was to keep the doors clean

and dry. To prevent the bottom of the doors from being submerged in water or muck, the design intent was to: (1) cross slope the drift near the bridge to divert any non-emergency and relatively low-flow emergency water away from the bridge pit, and into a drainage ditch that would be drained by a 12 inch diameter drain pipe running parallel to the Bulkhead, and (2) remove any accumulated water in the bridge pit by means of a sump pump. During emergency flow conditions, this sump pump was also intended to help prevent the water level in the bridge pit from rising too quickly, giving personnel more time to close the door under dry conditions.

• It was common knowledge that water and muck were present in the bridge pits on an ongoing basis.

• The design intent was to operate the doors free from moisture and muck. Having the bottoms of the doors submerged in moisture and muck would create a number of undesirable effects: rusting of the metal door gasket area; having to remove the muck prior to closing the doors in an emergency situation; and possible deterioration of the adhesive bonding the gasket to the door.

• During an inflow situation, water could flow along the drift towards the Bulkhead. Due to the drift cross slope design, some of the inflow water would be expected to drain into the drainage channel and then through the drainage pipe running alongside the Bulkhead. If the water flow rate exceeds the capacity of the drain pipe, or if not all of the inflow water flow drains into the drainage channel, the bridge pit would start to fill with water. As the bridge pit fills with water, the gasket would become immersed.

• From the documents examined, it is unclear: (1) what the preventive maintenance and/or inspection programme or schedule was intended to be; (2) if different types of maintenance activities (e.g., annual, quarterly) were to be performed; and (3) if there were different requirements (e.g., maintenance, inspection, verification).

• The work orders reviewed included requests for the following types of work: annual preventative maintenance; quarterly inspections; 60-day inspections; and 2-month inspections. All maintenance procedures/check sheets observed were labelled as 60-day maintenance procedures. Controls on document revision status, and on unintended use of obsolete documents, for example, do not appear to have been established and/or implemented during the period of interest.

• Recommended door maintenance activities were developed by the door designers and provided to CLMC. A 60-day maintenance procedure, using a checklist format, was developed by CLMC in about 1991. Although the look of the procedure has varied,

of 96 44

the content has remained similar. It could not be determined from the available documents and records, or from the personnel interviewed, what the maintenance programme or schedule was intended to be, and if procedures were established to correspond to the various types of work order requests issued (e.g., quarterly, annual).

• The door maintenance procedures reviewed by EMS Croscan require or imply that personnel are to determine if the gasket is in good shape or in good condition. The method for doing this is not specified.

• The door maintenance procedures include maintenance activities (e.g., remove scale); inspection activities (e.g., inspect door for damage); and verification activities (e.g., close door and record time). However, the door maintenance procedures do not address what to do if a missing, damaged or loose gasket is found during maintenance activities. No separate work instruction was found that describes how to replace missing, or repair damaged, gasket.

• When inspection or verification activities identify a deficiency, information about the non-conforming condition is recorded on the maintenance work order documents. This information is then entered into the maintenance management system, and another work order must be scheduled and issued to correct the deficiency. Maintenance activities are focused on the door assembly. However, in order for the entire Bulkhead to achieve its intended purpose, other equipment and devices (e.g., valves) must be physically and functionally capable of performing as intended. The scope of the maintenance procedures does not include maintenance and verification activities for all components of the “Bulkhead water control system.”

• Deficiencies were noted in relation to both the East and West Doors during an October 5, 2006 training exercise, but no Work Orders were generated to address those deficiencies.

Consultant Opinions • EMS Croscan examined the door maintenance procedures that were found to be in

use during October 2006, and judged that they were not fully adequate for the following reasons:

- The procedures do not specify how to inspect the gasket, e.g., visual, feel with bare hand.

- The procedures do not specify acceptance criteria for inspection activities. - In the absence of other procedures such as a “non-conformance control”

procedure or a “deficiency correction” procedure, there do not appear to be controls in place to ensure that deficiencies are dealt with in an appropriate manner.

- The procedures for the 480L doors include neither a requirement to clean out the bridge pit nor requirements related to maintenance or verification of other components of the water control system.

- The procedures do not clearly indicate what records are to be created. • EMS Croscan stated the following about the door maintenance schedule:

- Without knowing what the maintenance schedule was intended to be, it cannot be determined to what extent it was followed. However, based on

of 96 45

the available records, it appears that the maintenance schedule which was established or which emerged during the first several months of operation was not maintained.

- The maintenance procedures in effect prior to October 2006 do not explicitly prescribe what activities are to be performed. That is, the maintenance procedures list a series of questions and each question is followed by a space to enter a response. A checkmark or a Yes/No response was consistently entered after each question. If the intent was that the door should be fully closed each time maintenance was performed, then the procedure was not regularly followed in this respect.

• EMS Croscan stated the following about the door maintenance procedures being followed:

- There is insufficient evidence available to demonstrate that the door maintenance procedure in effect in October 2006 was fully followed. There is no evidence to demonstrate that the deficiencies found during the October 2006 inspection were addressed, or that there was a plan to address them.

- The door maintenance procedures in effect prior to October 2006 were not fully followed. Required signatures and dates were consistently not entered onto maintenance records.

- If the maintenance procedures in effect prior to October 2006 are interpreted to mean that the doors were to be fully closed, then this requirement of the procedure was regularly not performed.

• EMS Croscan stated the following about the effect on the gasket of the flowing water: - If the door is closed while water is flowing through the Bulkhead, the

gasket is exposed to the force of the flowing water. Depending on the position of the door, the water may be trying to curl the gasket up and either pushing it towards the outer wall or towards the inner wall of the groove. As the distance between the gasket and the stress transfer cylinder flange decreases, the force from the flowing water acting on the gasket increases. A weak adhesive bond and/or a reduction in friction coefficient between the gasket and the stress transfer cylinder flange would reduce the ability of the gasket to resist the force of the flowing water.

- It is highly probable that the flowing water and any debris carried by the water caused, or contributed to a section of the gasket becoming detached and/or dislodged from its groove.

- If the door is closed while water is flowing through the Bulkhead, the distance between the gasket and the stress transfer cylinder decreases, and the velocity of the water flowing between the gasket and the stress transfer cylinder flange increases. The flowing water creates what is referred to as a velocity or dynamic pressure that would, in this case, act upon the gasket. A commonly observed example of this principle is when a nozzle is attached to the end of a garden hose. As the nozzle outlet size is reduced, the water stream shoots farther and seems to have more force.

of 96 46

- If the door is not closed and cinched before the water level reaches the floor level inside the Bulkhead, then the face of the gasket that contacts the stress transfer cylinder flange is not constrained by a friction force. Water flowing past the gasket will be trying to push the gasket towards the inside of the machined groove, as well as trying to lift and peel away the gasket. These forces, and any impact from debris picked up and carried by the flowing water could potentially cause the gasket to tear or cause the adhesive bond to fail, resulting in a gap in the gasket. A dislodged piece of gasket could, for example, become pinched between the flanges, preventing full flange to flange contact.

- A reduction in the friction force between the gasket and the stress transfer cylinder flange would reduce the force required to slide the gasket against the stress transfer cylinder flange. Water, oil or grease on the gasket or flange would be expected to reduce the friction force.

- Any deterioration of the gasket adhesive prior to an inflow condition would also be expected to reduce the ability of the gasket to withstand the force of flowing water.

• EMS Croscan stated the following about the effect on the gasket being underwater: - The gasket material (nitrile rubber) is expected to be unaffected by being

underwater. - It could not be determined with certainty in what way or to what extent

water affected the adhesive(s) used to attach the gasket to the door flange. However, the information gathered indicates that the adhesive(s) were not totally effective under the conditions encountered.

- Maintenance personnel reported, and maintenance records show, that sections of gasket were found to be loose or missing on the 480L 725 XCN door [East Door] on four occasions dating back to February 2004.

• The gasket was the original seal on the West Door. It is only glued on, not vulcanized. • The MTM supervisor at the West Door when it closed estimated that the flowrate was

less than 1,000 gpm (or 270 m3/hr) when the gasket was observed to be hanging out. • The West Door is 14 feet in diameter and the gasket is in segments. There are 4 large

segments attached together. The East Door is a 12 foot diameter door. • The sumps are frequently filled to the bottom of the bridge on both the east and west

sumps. The bottom of the door is definitely in water most, if not all of the time. • Step #10 of the June 12, 1990 Bulkhead Closing Procedure from CESL states "Apply

enough load evenly to compress the gasket seal approximately 1/16 of an inch.” It may be that when the door was tightened from the bottom, a section of the gasket popped out of the groove due to uneven tightening.

• The Cigar Lake Underground Water Control Bulkhead Door Closing document (199-001-01-Rev-0) states only that "…..Tighten the come-alongs until the door is fully seated.” There is no mention of the need to evenly tighten the come-alongs.

• Maintenance records also show that on four other occasions, including October 2006, the gasket on the East Door was found to be missing or loose. It was stated during the

of 96 47

February 1, 2007 interview that contact cement, applied with a paint brush, was used as an adhesive to attach the gasket to the door.

• The specifications for the adhesive originally used on the 480L door gaskets could not be determined. Maintenance personnel reported that the adhesive used to re-attach sections of gasket that had come loose, or to install sections of new gasket, was a “contact cement” type of product.

• The Cameco Construction Manager stated that he went back to the West Door at 06:00 hours and water was coming down the drift. He estimated that water was leaking from the door crack on the bottom, at about 200m3 per hour. No measurement was taken at that time.

• The Construction Manager observed that an MTM crew was working on tightening the door using a scoop and come-alongs. There was roughly a 3/16 inch gap caused by a 4 foot length of gasket at the bottom of the door (the MTM supervisor on the job described it as a 4 foot length of gasket). The end of the gasket was clean and was not torn. He reported this to surface at 06:05 hours.

Interview Data • The investigation found that many individuals had comments relevant to this Causal

Factor. Once again, recognizing these are opinions and beliefs (and not fact), those comments help to explain this Causal Factor:

- The MTM worker who carried out extensive maintenance on the doors

over the years expressed his view that the pit for the door should not be used as a sump. He indicated that he mentioned this many times. He also indicated that there was no special glue to hold the gasket. In his opinion, water could have affected the glue.

- In an interview with Cameco and MTM personnel at Cigar Lake on February 1, 2007, they stated that the gaskets on both the West Door and the East Door were found to be loose or missing on a few occasions. They noted, as an example, that a section of gasket on the East Door had to be replaced in late 2005 or early 2006. Since no gasket was found to be available in inventory, a section of gasket was removed from the 420L door (it is the same diameter as the East Door). The gasket easily peeled off the 420L door, and was not damaged by this activity, allowing it to be re-used on the East Door. A purchase order for gasket material and adhesive was issued January 6, 2006.

4.7 Causal Factor #7 – The decision to force the West Door open at 08:10 hours to repair the gasket led to an increased flow through the door

Discussion of Causal Factor The understanding in the Command Centre, throughout the morning of October 23, 2006, was that the gasket was necessary to effectively seal the door. The Head of the Command Centre stated that this has been his understanding ever since the doors were installed in

of 96 48

the early 1990s. In reviewing the design documentation, the purpose of the gasket is to provide an initial seal while the hydrostatic pressure builds behind the door. As the pressure builds the gasket will aid in sealing any imperfections between the two steel flange surfaces. The door was not designed to be closed (or opened) in flowing water. No direct reference was found in the available design documents that the door needed to be designed for closing in flowing water. A File Note document dated January 25, 1991 contemplates that it could be difficult to close the door in flowing water. A June 12, 1990 File Note document states that once the doors were closed, they should not be re-opened under flowing water conditions. Similar statements are made in the Cigar Lake Underground Water Control Bulkhead Door Closing documents. Water flow against the doors would force them to close very rapidly, and should a door not close square to the stress transfer cylinder flange, any attempt at correcting misalignment would be increasingly difficult as the water level rose behind the door. The selected gasket design called for it to be placed in a groove and cemented to the door flange for a permanent bond. The gasket was also to be placed in the centre of the groove, so that the gasket material could uniformly deform within the groove as it was being compressed. Given these conditions, the gasket would need to be installed in a dry, clean setting and not under flowing water conditions. The door gasket was designed to be permanently bonded to the face of the machined groove in the door flange, using an adhesive applied in clean and dry conditions. EMS Croscan determined that the door could be closed without a sealing gasket. However, they indicated some leakage might occur, depending on the seal achieved between the metal door flange and the metal stress transfer cylinder flange. Factors that might affect the seal being achieved include the flatness, squareness and alignment of the flanges, the level of water pressure acting on the door and the presence of foreign material between the flanges. Assuming a gasket in new condition is seated in the centre of the groove, complete metal to metal (flange to flange contact is not attainable until the full gasket compression pressure is reached. If the gasket is damaged or a section of the gasket is missing, water will flow through the resultant gap in the affected area. The double hinge door design was selected primarily to allow the door flange to be seated squarely against the stress transfer cylinder flange and to transfer the force of the water directly onto the stress transfer cylinder. The information noted above describes the double hinge design for closing the doors and the rationale for this approach. It also indicates that the doors could be closed without a gasket in place. Under this scenario, there would be leakage during door closure until the door was seated tightly against the stress cylinder, at which time leakage would be limited to imperfections of the metal to metal contact between the door flange and the stress cylinder flange. Again, the Command Centre was of the understanding that the entire gasket was necessary to create a viable seal. If the Command Centre had been better informed regarding the designed function of the gasket during the duration of the door closure, additional consideration may have been given to alternate sealing options, such as placing concrete or grout behind the door.

of 96 49

Basis for Causal Factor • The understanding of everyone in the Command Centre was that the gasket was

necessary to effectively seal the door. The Head of the Command Centre stated in an interview that this has been his understanding ever since the doors were installed in the early 1990s. He was clear in describing the Command Centre as being on a 'mission' to get that gasket back in place.

• Those individuals in the Command Centre did not have an effective appreciation of the conditions underground at the West Door. Those workers and supervisors at the West Door after it was first closed at approximately 05:30 hours stated in their interviews that there was no way they wanted to open it again. The understanding held by those in the Command Centre was quite different. They could not believe there was much water built up behind the door. They did not have video access to the conditions underground and if they had, the decisions taken may have been different.

• At 06:30 hours, the Area Co-ordinator was instructed by the Head of the Command Centre to go underground to try to open the door slightly, and to insert some rubber gasket material to create a seal.

• It appears, from reviewing the design documentation, the rubber gasket on the door is intended to provide an initial seal. The design documentation clearly indicates that the primary sealing mechanism, when hydrostatic pressure has been achieved, is through metal to metal contact between the door and the stress transfer cylinder on the Bulkhead. The intent of the gasket after this point is to aid with any imperfections in the metal surfaces.

• One interviewee recalled that, later in the morning of October 23, 2006 when things were in crisis mode in the Command Centre, someone asked if the gasket in the door was really necessary. No-one knew. The interviewee remembered stating that he did not know whether the gasket was necessary. He said that one of the technical support personnel was doing some calculations to estimate the amount of water that would come through a 6 mm (1/4 inch) gap (i.e. the 13 mm (1/2 inch) gasket stuck in the door would be compressed to 1/4 inch).

• A technical resource person arrived in the Command Centre between 06:00 hours and 06:30 hours on October 23, 2006. The gasket had already separated. This individual was capable of performing leak calculations, and started looking for prints of the door (he indicated he knew where to look).

• At one point, the technical resource person remembers attempting to estimate the flowrate without a gasket at all. He recalls that estimate being much larger than the pumping and treatment capacity of the mine. That calculation confirmed the Command Centre’s belief that they needed to get the gasket in place.

• Several individuals admitted in their interviews that no-one had a good understanding of how that gasket was supposed to work. They simply believed they needed it.

• At one point early on in the morning, the technical resource person attempted to find the installation procedure for the gasket and was unsuccessful.

• The following Table shows the estimated water flows through various gap sizes and for various levels of water behind a gate used as a model of the door. A fixed orifice length of 130 mm was used for all calculations. Results are provided in m3/hour. By

of 96 50

necessity, a number of assumptions were made in estimating flows, such as a uniform width of gap around the circumference of the door, and the flow characteristics through the gap. These calculations were made by a consulting hydraulics engineer.

Table Leakage (m3/h)

Gap width (mm)

Head on gate (m) 3.2 4.8 6.0 10.0 12.7 0.25 26.0 42.6 55.1 96.8 125 0.50 53.0 86.4 112 196 252 0.75 80.6 131 169 297 382 1.00 109 177 228 399 514 1.25 138 224 288 504 650 1.50 167 271 350 612 788 1.75 198 320 413 721 929 2.00 229 371 478 834 1074

• During the first attempt to close the West Door, the gap width, as documented in the minutes of the Command Centre, was between 3.2 mm (1/8 inch) to 4.8 mm (3/16 inch). During an interview with the MTM worker who actually supervised the closing of the West Door, he stated that the estimated depth of flowing water within the Bulkhead was 6 inches (152 mm).

• While leakage was initially estimated at 200 m3/h, based on a gap size of 3.2 mm (1/8 inch) to 4.8 mm (3/16 inch), the flow rate was recalculated to be 800 m3/h. This estimate of 800 m3/h, which exceeded pumping capacity, caused the Command Centre to direct the door to be reopened at 08:10 and 10:35 hours.

• It is difficult to estimate the water flow when there is metal to metal contact between the door and stress cylinder flanges (with or without a gasket in place). If there was complete contact, i.e., the doors were completely square, and there were no imperfections in the surfaces of the two flanges, then theoretically there would be zero flow when large hydrostatic forces act on the door.

• The MTM supervisor, who was involved in closing the West Door when it first exhibited a leak, stated in an interview that his immediate idea was to put sandbags on the door and pump concrete through the door to harden on the other side. He explained that it would have taken 2 hours to set it up, and another day for the concrete to set. Upon being asked whether he thought this would have worked, he replied that he had done it before in a similar situation, and it had worked great.

• A discussion took place between the two senior MTM and Cameco personnel underground and the Command Centre when the gasket first came loose. This took place at approximately 06:15 hours. In his interview, the MTM supervisor recalled the Head of the Command Centre stating that "you've got to open the door and get the gasket in place." He remembered quite clearly that no consultation took place.

• The alternative option of pumping concrete through the Bulkhead utility pipes to restrict and ultimately seal the door from the wet side was given consideration and rejected by the Command Centre. The Head of the Command Centre understood that a fully intact gasket was vital for effective sealing of the door.

of 96 51

• In an interview, the MTM supervisor expressed the fact that he was very disappointed with the decision, and could tell that the Cameco supervisor also disagreed with it. They were of the opinion "why not take what you have and move forward?” He recalled telling the Command Centre that "we could handle the water.”

• The MTM Supervisor went to surface at approximately 07:00 hours, fully expecting that the decision would be reversed. He was later surprised to learn that it was not.

• A similar option, involving burlap and grout, was tabled and pursued over 2 ½ hours later, after the unsuccessful 08:10 door opening.

• Visual estimates indicate that water flow through the door worsened after the 08:10 re-opening.

• At the time of this door opening, the water spray was violent and stung the face of the load haul dump operator.

• The Command Centre’s decision to open the door was made without first-hand knowledge of the conditions. There were no video feeds underground.

• The CLMC Bulkhead Closing Procedure dated June 12, 1990 states, in step #8 that "…..once the door has contacted the stress transfer cylinder and water is rising behind it, the door cannot be reopened.”;

• The Cigar Lake Underground Water Control Bulkhead Door Closing document (199-001-01-Rev-0) states in italics, on page 10: "Once the door catches any water current, it will close quickly so ensure that no one leaves the bulkhead to help it along. Once the door is closed, it will be held in place by water pressure and cannot be reopened until the source of the water is controlled.”

• In a June 12, 1990 File Note, prepared by the second CESL designer regarding the CLMC Bulkhead Door Closing Procedure, item 8 reads:

"Ensure all personnel are safely on the shaft side of the bulkhead (once the door has contacted the stress transfer cylinder and the water is rising behind it, the door cannot be re-opened. Therefore ensure that no one is standing to the side to watch it close).”

• The approach selected by the CESL designers in 1991 involved installing a gasket in a groove made in the door flange. Under this approach, when the gasket was compressed 50%, metal to metal contact occurred between the door and stress transfer cylinder flanges. This metal to metal contact was considered important for the transfer of the water pressure load to the stress cylinder, and not to the door hinges. It was estimated that for the 420L door, a pressure of 39.1 psi was needed to compress a 40 Durometer nitrile gasket 50%, and a 50 psi pressure was needed to compress a 45 Durometer nitrile gasket 50%. A water head of about 90 feet would produce a pressure of 39 psi on the 420L door.

• Specification Sheet 11696, Sheet 1 Rev. 2 prepared by the CLMC Project Manager and dated March 7, 1990 shows that a 1 inch x 1/2 inch thick 40 Durometer nitrile gasket was selected, with a note to "cement to flange for permanent bond.”

• Engineering calculations dated June 2, 1990, performed by one of the original CESL designers for the 420L 725 XCN door indicate that:

of 96 52

1) the design intent is for full metal to metal (flange to flange) contact; 2) metal to metal contact occurs when the gasket compresses by 50%, and 3) the deformed gasket material (40 Durometer nitrile) is assumed to fill the

machined groove in the door flange. The water pressure calculated by CESL to be required to compress the gasket by 50% is 39.1 psi (39.1 psi x 2.306 ft of water/psi = 90.16 ft of water).

• Specification Sheet 11696, Rev. 2 called for the door flange surface preparation to be 125 rms. A surface preparation of 125 rms is suitable for static mating surfaces. This provides technical confirmation that metal to metal contact between the two surfaces could result in effective sealing at full hydrostatic pressure as long as other impediments were not present (ie. corrosion, deformation, foreign material).

• A manuscript, prepared in November 1991 by one of the two CESL door designers for presentation at the 1992 annual meeting of the Society for Mining, Metallurgy and Exploration Inc., explained the major components of the Bulkheads. The following are excerpts relating to the gasket between the door and the Bulkhead stress transfer cylinder and door hinge mechanisms:

"The gasket between the door and the bulkhead is accommodated in the circumferential flange, as shown in Figure 6. The recessed gasket seat was provided on the door for a 60 Durometer nitrile rubber gasket. The gasket deforms elastically under load until the door flange meets the cylinder flange. The load is then transferred by bearing from machined steel surfaces.” "Each bulkhead door is equipped with a hinge and bearing mechanism that enables the doors to close easily with only the minimal effort supplied by one man. Chain tighteners were provided to apply a small pre-compression of the door gaskets and thereby assure initial watertightness.”

• At 06:15 hours, the Command Centre log shows that the General Manager requested the 12 inch valves be opened to relieve pressure for preparation to put a gasket in. There is no evidence that this ever happened.

• Prior to the door opening at 08:10 hours, one technical resource person interviewed did not recall any discussions in the Command Centre regarding opening the 12 inch valves to reduce water behind the doors.

• The same technical resource person recalled that the Command Centre did talk about draining water through the East Door for a while. However, they decided against this action, as they had the East Door closed and did not want to open it and risk ending up with two problem doors.

• The crew needed an LHD to push the door open at 08:10 hours (over 2 hours after it was initially closed). The LHD operator was described as receiving a red burn on his face from the fine spray that came blasting through when the door was opened.

• One individual interviewed recalled that it was scary when we opened the door for the first time at 08:10 hours. He described it sounding like a whale blowing through its blow hole. He stated that the door slammed shut when they backed off. They then relayed this information back to the Command Centre. The personnel underground stated that they clearly knew they did not want to reopen that door.

of 96 53

• The Head of the Command Centre believed that the depth of the water for the first door opening attempt at 08:10 hours was approximately 9 inches to 1 foot. This was clearly an underestimate. The Head of the Command Centre acknowledged during his interview that the Command Centre did not have a true appreciation of what the personnel in the Bulkhead were facing.

• The Command Centre also believed there was a significant amount of water flowing through the door after it was closed with a piece of gasket out of place at 06:00 hours.

• One senior person stated in an interview that ‘we never considered needing to close the door under 1,500 m3/hr. The studies resulting in the door design did not suggest maximum inflow close to this high.’ The Procedure pertaining to the door closing was not updated after the McArthur River inflow demonstrated that much higher flowrates were possible.

• In an interview, the Head of the Command Centre described the Command Centre's belief that the water would go to the north workings of the mine and would not build up behind the door. He estimated that there is roughly 10,000 m3 of available volume at the north End of the mine, and that there is only a 1% slope to overcome to access the storage.

• At that point, a suggestion was made by the underground crew to get burlap, wet it, and then stick it through the pipes so that the leak would draw the burlap through. The crew would then get a grout pump, jam burlap in front where the gasket was, and get some grout in there.

4.8 Causal Factor #8 – The decision to force the West Door open at 10:35 hours to repair the gasket led to debris being caught in the door which caused a significantly increased flow through the door

Discussion of Causal Factor This Causal Factor involves similar factors to those present for Causal Factor 4.7. One factor that was different was the fact that roughly 2 ½ hours had passed since the previous door opening attempt. This meant that the water level behind the West Door was significantly higher, and posed an even greater hazard. Basis for Causal Factor

• 2 hours and 25 minutes were spent preparing for the grouting option, using burlap. While nearing completion of their preparations for the burlap and grout attempt, the Head of the Command Centre instructed the Area Coordinator to open the door once again, and to attempt to insert the gasket. The plan to use burlap and grout was abandoned, based upon calculated maximum flow rate through the West Door, the available pumping capacity and the remaining storage volume available underground.

• Water levels had been increasing behind the door all this time. However, the Head of the Command Centre stated in an interview that the belief in the Command Centre was that the water level should only have been slowly rising behind the door.

of 96 54

• The water level behind the West Door was estimated at approximately 4 feet deep at 09:10 hours by the personnel underground.

• The Cigar Lake Door Closing Procedure (199-001-01-Rev-0) states in italics, on page 10: "Once the door is closed, it will be held in place by water pressure and cannot be reopened until the source of the water is controlled.” Opening the door to repair the seal was felt to be of more importance during the morning of October 23, 2006.

• The water behind the West Door was still estimated to be 4 feet deep. The underground crew described using the pipes on the side of the Bulkhead to walk on.

• The Command Centre’s idea was to open the door to equalize the water on both sides, so that a crew could gain access to and repair the gasket.

• The two most senior Cameco and MTM personnel underground indicated in their interviews they were not keen on the idea of opening the door again. The MTM worker asked the Cameco worker whether he thought the Command Centre was kidding. However, no significant protest appeared to have been made.

• The Head of the Command Centre believed that the water was less than 1 m high behind the door on the second to last door opening.

• The Head of the Command Centre indicated in an interview that he felt they were rapidly running out of time for options, as they were measuring the levels on the 500 m elevation and in the shaft. He stressed that he always wanted to maintain a time window at the end to ensure they could get everyone out.

• The Command Centre attempted to contact one of the CESL door designers to obtain some advice and guidance, but was unsuccessful as the door designer had been struck by a car that morning.

• At 10:35 hours, the underground crew opened the West Door at least 2 feet using an LHD. At this point, 2 ½ hours had passed since the last door opening. A large rush of water immediately came through the door from the water backed up behind it.

• When this was attempted, an MTM supervisor recognized that the electrical infrastructure for pumping water was compromised by the surge of water. The supervisor communicated this information to the West Door, and it was immediately closed.

• The opening at 10:35 hours led to a plastic object being caught between the sealing surfaces of the door and the stress transfer cylinder, which resulted in a greater flow rate through the door.

of 96 55

4.9 Causal Factor #9 – Forcing the door open further than intended at 11:09 hours resulted in the door being left open

Discussion of Causal Factor At this point in the sequence of events, the situation had deteriorated significantly, and everyone agreed a last ditch effort was needed to prevent the mine from flooding. In the process of this final door opening attempt, there were some frightening moments, as described by those involved and by those close by. Fortunately, everyone was able to get out of the mine safely. One thing not anticipated by those planning the final opening was the water getting behind the West Door and preventing it from being closed. If this had been anticipated, they may have kept the turnbuckles attached to the door, thus limiting the amount by which it could swing open. Basis for Causal Factor

• Everyone agreed that this action was necessary to save the mine from being flooded. • The concave shape of the West Door resulted in the door being forced open by the

water pressure exerted on the inside of the door while flowing past. • Large debris (timbers, toolboxes, etc.) flowed through the West Door opening. This

may also have affected the ability to close the door. • The worker at the West Door was struck with debris and had water coming over his

shoulders. This is an indication that the water level behind that door was at least 5 feet deep.

• It is possible that the LHD scoop opened the West Door further than intended. Prior to attempting the door opening, the turnbuckles were removed from the door. This had the result of allowing the door to open further than intended.

• The 2 x ¼ inch wire ropes attaching the LHD scoop to the West Door snapped when attempting to close the door.

• The sudden and large inflow of water created higher risk conditions, which could have led to serious conventional safety consequences (e.g. drowning, hypothermia).

- The safety hazards encountered while opening the door at 11:09 hours were not fully understood, and were therefore underestimated by all involved.

- The magnitude or the potential consequences of the inflow were not fully appreciated prior to opening the door at 11:09 hours. No-one anticipated that the door would be opened and would not able to be closed.

- There were 24 people underground at this point. Several individuals interviewed felt strongly that this number was too high, and that non-essential people should have been removed prior to the final door opening attempt.

of 96 56

- Unlike the system for sweeping the north end of the mine prior to closing the doors, there was no effective system for accounting for individuals and for their locations prior to the last cage going up.

- Personnel subjected to cold water temperatures for a prolonged period of time indicated in their interviews that they received no medical support on the surface.

of 96 57

5.0 CORRECTIVE ACTION RECOMMENDATIONS

Corrective Actions Matrix

Causal Factor #1: Construction on the 465-944 DRE was started prior to having adequate emergency water pumping & treatment systems in place


CAR 1-1

• Cameco needs to carry out a detailed review of the decision making process leading up to approval being given to develop the 465-944 DRE prior to completing the emergency pumping and treatment expansion at Cigar Lake. This needs to include:

• a) an examination of any associated corporate and site risk assessment Standards (i.e. policies and procedures, etc.);

• b) the extent to which Cigar Lake complied with corporate Standards and regulatory constraints in deciding to proceed with the development of the 465-944 DRE prior to having emergency pumping and treatment capacity in place;

• c) the extent to which Cigar Lake factored in the McArthur River and Cigar Lake Shaft #2 water inflow incidents into the decision to proceed with development in the 465-944 DRE; and

• d) whether the Standards need to be revised to more exactly and strictly define the requirements that meet corporate management's expectations.

• Standard Not Strict Enough

of 96 58


Causal Factor #1: Construction on the 465-944 DRE was started prior to having adequate emergency water pumping & treatment systems in place


CAR 1-2

• If and when Cameco has revised their policies and procedures in this area, they will need to communicate them to all affected personnel (managers, supervisors, workers, contractors, etc.) and ensure they are implemented

• Standard not communicated to everyone who needs to know

CAR 1-3

• Cameco then needs to audit, throughout the organization, the application of the decision making process involving risk, in order to assess and verify that corporate and site Standards are being used as intended.

• Audit Program not examining all areas in sufficient depth

CAR 1-4

• Cameco needs to ensure that all affected mine sites have approved contingency plans in place to help them effectively prepare for and aid decision making in response to acute water inflow situations. These plans need to be integrated with corporate programs and include, but should not be limited to, the elements of:

- Credible water inflow risk scenarios & mitigation measures; - Detailed Procedures (including the need for sequencing); - Contingency response team selection and training; - Emergency equipment and material requirements; - Communication (including audio and video); - Organizational responsibilities and authorities (including

decision making responsibilities of Command Centre and on scene personnel);

- Underground Accounting of Personnel (tag boards, sweeping, etc.);

• No Formal Contingency Plan or Procedures

• Management System - Accountability Needs Improvement

• Communication - Communication System Needs Improvement

• Training - Practice/Repetition Needs Improvement


• Human Engineering - Tools, Instruments & Materials Need Improvement

of 96 59


Causal Factor #2: The Engineered Mine Plan for this intersection was not sufficiently conservative given the geology encountered, the existing resources and conflicting priorities at Cigar Lake


CAR 2-1

• Cameco needs to develop, and put in place, a formal process to ensure that consultants’ recommendations are reviewed by the appropriate individuals and effective actions are taken.

• An integral part of this process will require obtaining and seriously considering input from appropriate site and corporate technical consultants prior to decisions being made above a defined risk level.

• The process needs to require explicit justification and an appropriate level of authorization for any deviations on actionable items arising from consultant/expert recommendations.

• Communications - Turnover process Needs Improvement


CAR 2-2

• Cameco needs to develop and implement a set of rigorous corporate ground support Standards for mine designers to use.

• The Standards need to specify quality requirements and include any appropriate precautions relating to installation of ground support. Once the Standards have been implemented, they need to be periodically audited to ensure they are having the desired result.

• There is also the need to secure the resources to meet the requirements implicit in the Standards.


of 96 60


Causal Factor #2: The Engineered Mine Plan for this intersection was not sufficiently conservative given the geology encountered, the existing resources and conflicting priorities at Cigar Lake


CAR 2-3

• Cameco needs to develop and implement a set of rigorous corporate standards for the entire mine development cycle which starts with drilling and blasting and ends with completed ground support. In addition to other important elements, the standards need to explicitly address:

- Quality requirements; - Ground support as an element of overall ground control; and - Geological and geotechnical mapping;

• There is also the need to secure the resources to meet the requirements implicit in these standards.

• Provision for effective communication between Cameco mine staff and mining contractor staff should form part of the standards, in order to achieve a team approach to the planning and execution of the ground support cycle.

• Standards, Policies, or Admin. Controls Need Improvement

• Standards, Policies, or Admin. Controls Not Used - No Way to Implement



of 96 61


Causal Factor #3: A significantly larger span than the Engineered Mine Plan called for was excavated at the 465-944 DRE and 465-773 LCH intersection


CAR 3-1

• Cameco needs to develop, and put in place, effective corporate Standards for controlling and reporting over-excavation.

• The Standards should be developed in conjunction with the mine contractor and clearly specify how blasting, including controlled blasting, is to be carried out.

• When approved, they need to be incorporated into mine contractor's own policies, procedures and work methods.

• The implementation needs to be enforced and periodically audited against the appropriate Standards.

• No Procedure • Procedure Wrong - Situation Not

Covered • Procedures Followed Incorrectly -

Details Need Improvement

CAR 3-2

• Cameco needs to formally review its criteria specifying when and how certain types and sizes of mining equipment are used. The criteria should be developed in consultation with the mine contractor to ensure that appropriately sized equipment is available and used at all times.

• This will require Cameco to communicate short and long term mine planning decisions to the mine contractor.

• Cameco needs to enforce the equipment selection and use criteria and periodically audit its application.

• Procedure Wrong - Situation Not Covered (no mention of jackleg)

• Procedures Followed Incorrectly - Details Need Improvement

• Communication of Policy Needs Improvement

• Drawings Need Improvement • Resources Need Improvement • Enforcement Needs Improvement

of 96 62


Causal Factor #3: A significantly larger span than the Engineered Mine Plan called for was excavated at the 465-944 DRE and 465-773 LCH intersection


CAR 3-3

• Cameco Cigar Lake needs to review its organizational related interfaces with the MTM organization and determine what, if any, changes need to made in responsibilities, job descriptions, job titles, oversight, lines of communication, audits and assessments, etc. in order that MTM consistently carry out quality work as specified by Cameco.

• The organizational review needs to include an assessment of the advantages and disadvantages of using Contract Area Coordinators at Cigar Lake and Cameco Mine General Foremen at most other mines.

• This issue is also related to CAR 2-3.

• No Reasonable Level of Supervision


• Resourcing Needs Improvement




of 96 63


Causal Factor #4: The specified ground support was not applied in a timely manner


CAR 4-1

• In addition to the CAR 2-3, Cameco needs to carry out an in-depth review of the ground control program at all of its mine sites with a view to identifying organizational and technical weaknesses and missing elements.

• Effective actions need to be taken to address any identified weaknesses and missing elements. Strengths at any individual mine site need to be shared, and implemented where applicable, at other mine sites.

• Cameco needs to decide what level of authority needs to be responsible for ground support decisions. Strong consideration should be given to a senior engineer for the mine site with experience in ground control being responsible for ground support decisions.

• Cameco and MTM, at all mine sites, need to determine what changes are necessary in their current processes and how they are going to work differently together in future to ensure ground control requirements are consistently achieved.

• A process needs to be implemented whereby corporate and external ground control consultants conduct periodic audits of each site’s ground control program and report findings to the Site General Manager and the VP - Mining. The process needs to be modified such that the audit findings are effectively and formally dispositioned by an appropriate level of authority.

• Leadership for Ground Control • Policy Not Strict Enough • Policy Confusing or Incomplete • Communication of Policy Needs

Improvement • Infrequent Audits and

Evaluations • Understanding of Ground

Control- Learning Objective Needs Improvement



of 96 64


Causal Factor #5: The initial attempt to close the West Door was not completed in dry conditions as specified in the design


CAR 5-1

• Cigar Lake needs to carry out a detailed review of all aspects of its Bulkhead door closing process to identify critical elements that need to be in place and any current weaknesses and gaps in those elements. Included in this review, needs to be an examination of:

- Door Closing Policies & Procedures (including if and how the doors can be closed or opened in the presence of water);

- Deterioration of the Bulkhead, the doors and components due to water, muck, etc. during normal and emergency conditions;

- Organizational responsibilities, including decision making authorities during an acute water inflow event;

- Design intent and requirements; - Related training & retraining of Cameco and MTM personnel,

including consideration for personnel turnover; - Preventive Maintenance; - Tools and Instruments needed to ensure effective door closing; - Communications (merits of a video link between the Command

Centre and the door closing crew, effective telephone/radio links); - Records & document control associated with all above elements; - Contingency plans in the event a door does not close and seal;




• Preventive Maintenance for Equipment Needs Improvement

• Procedures - Details Need Improvement

• Training - Practice & Repetition Needs Improvement

• Human Engineering - Tools & Instruments Need Improvement

• Human Engineering - Human/Machine Interface - Displays Need Improvement

CAR 5-2

• Cigar Lake needs to take effective and timely corrective action to address the deficiencies and weaknesses identified in CAR 5-1 above;


of 96 65


Causal Factor #6: Upon adjusting and closing the West Door, a section of gasket separated from the door flange, resulting in water flow through the door


CAR 6-1

• Cameco needs to carefully examine the advantages & disadvantages of using Bulkhead doors as a final safeguard at Cigar Lake, considering the experience of the 2006 mine flood. Based on the results of this examination, Cameco needs to decide whether to retain the Bulkhead doors as an important water mitigation barrier;

• Management System - Policy Needs Improvement

CAR 6-2

• If, after carrying out the examination in CAR 6-1, Cameco decides to continue with the use of the Bulkhead doors at Cigar Lake, it needs to carry out a comprehensive hazard analysis (detailed risk assessment) as detailed in CAR 5-1 to identify:

- all significant hazards (risk scenarios) associated with the doors; - existing controls (design, operational and maintenance); - the relative strength or weakness of the existing controls; and - any changes or additions necessary in the design and/or the

organizational controls to ensure the Bulkhead doors work as intended if and when they are needed in future;


• Design Review - Management of Change Needs Improvement



• PM for Equipment Needs Improvement


CAR 6-3

• Cigar Lake needs to take effective and lasting action as detailed in CAR 5-1 to address weaknesses identified in the above assessment;

• Cameco needs to periodically carry out audits of the Bulkhead doors to ensure they are maintained in a state of operational readiness;


• Mgm’t System Oversight - Infrequent Audits & Evaluations

of 96 66


Causal Factor #7: The decision to force the West Door open at 08:10 hours to repair the gasket led to an increased flow through the door


CAR 7-1

See Causal Factor #5 - CAR 5-1, 5-2; See Causal Factor #6 - CAR 6-1, 6-2, 6-3;


Training - Task not Analyzed Management System - Policy

Not Strict Enough Complex System - Knowledge

Based Decision Required


Causal Factor #8: The decision to force the West Door open at 10:35 hours to repair the gasket led to debris being caught in the door which caused a significantly increased flow through the door


CAR 8-1



Training - Task not Analyzed Management System - Policy

Not Strict Enough Complex System - Knowledge

Based Decision Required

of 96 67


Causal Factor #9: Forcing the door open further than intended at 11:09 hours resulted in the door being left open


CAR 9-1



CAR 9-2

• Cameco needs to carry out a detailed risk assessment to: - identify the personnel safety related hazards experienced in the

October, 2006 incident; - identify the availability and effectiveness of controls used to

manage personnel safety related risk; and - make recommendations for improvements;


CAR 9-3 • Cameco needs to ensure that all affected mine sites develop and implement approved contingency plans for addressing personnel safety as part of an acute water inflow incident. The recommendations from CAR 9-2 need to be incorporated into each site’s contingency plan as defined by CAR 1-4;


of 96 68

APPENDIX 1 - CAUSAL FACTORS - RELATIONSHIP TO EACH OTHER & THE CIGAR LAKE MINE FLOODING

of 96 69

Construction on 465-944 DRE drift was started prior to having adequate emergency water pumping & treatment systems in place

Cigar Lake decides to advance along drift 465-944 DRE

Decision made to first expand the emergency pumping & treatment capacity to 1,500 m3/hr

Cigar Lake has ability to pump & treat significant flowrates. Expands options available. Mine not flooded

The Engineered Mine Plan for this intersection was not sufficiently conservative given the geology encountered, the existing resources and conflicting priorities at Cigar Lake

Cigar Lake provides for additional support in intersections or strengthens other controls

Fall of ground does not occur, even with geology encountered, as support and/or other controls are strengthened

A

Causal Factor #2 Causal Factor #1

of 96 70

Tolerance for adverse geology is much greater. Fall of ground is less likely

Even with the geology encountered, the back does not relax. Fall of ground unlikely

B

A

A significantly larger span than the Engineered Mine Plan called for was excavated at the 465-944 DRE and 465-773 LCH intersection

465-944 DRE and 465-773 LCH intersection is excavated in accordance with the Engineered Mine Plan

The specified ground support was not applied in a timely manner

Ground support is applied in a timely manner

Causal Factor #3 Causal Factor #4

of 96 71

Underground crew has time to react to the problem, squaring the door prior to water reporting to the West Door. Door successfully seals

B

The initial attempt to close the West Door was not completed in dry conditions as specified in the design

The initial attempt to close the West Door was completed in dry conditions as specified in the design

West Door successfully seals in a similar manner to the East Door

Upon adjusting and closing the West Door, a section of gasket separated from the door flange, resulting in water flow through the door

Gasket remains intact on the West Door, resulting in no water flow through the door

Causal Factor #6

C

Causal Factor #5

of 96 72

Door leaks initially until hydrostatic pressure builds and presses the door to a steel to steel contact with stress transfer cylinder. Or flow restricted until other options carried out

The decision to force the West Door open at 10:35 hours to repair the gasket led to debris being caught in the door which caused a significantly increased flow through the door

Abandon attempts to repair gasket and pursue other options (e.g. continue with burlap and grout option.)

Door leaks initially until hydrostatic pressure builds and presses the door to a steel to steel contact with stress transfer cylinder. Or flow restricted until other options carried out

The decision to force the West Door open at 08:10 hours to repair the gasket led to an increased flow through the door

Abandon attempts to repair gasket and pursue other options (e.g. pump concrete behind the door.)

C

Causal Factor #8

D

Causal Factor #7

of 96 73

Debris removed to allow steel to steel contact. Door able to be closed or flow restricted until other options carried out.

D

Forcing the door open further than intended at 11:09 hours resulted in the door being left open

Turnbuckles kept intact to ensure door opened only enough to remove debris

Causal Factor #9 October 23, 2006

Cigar Lake Mine Floods

of 96 74

APPENDIX 2 - SNAPCHART® OF EVENTS & CONDITIONS SHOWING WHAT HAPPENED LEADING UP TO AND FOLLOWING

THE MINE FLOOD INCIDENT AT CIGAR LAKE ON OCTOBER 22, 2006

of 96 75

About 01/01/1991

Design andinstallation of

Bulkhead Doors

As control forpotential water inflow

Geotechnical & hydrotech challenges to

overcome

Mine plan developed Mining methodstested

Several consultantsused

Geo/hydro technicalchallenges requireunique method of

extracting Uranium

Design by ComincoEngineering Services Ltd.

Operated by Cigar LakeMining Corp. Was a JV

between Cameco &AREVA as major partners

Cigar Lakechallenging resource

to mine

A

of 96 76

About 01/01/2002

Operating Cigar Laketaken over by

Cameco

22/03/2002

Geotechnical reviewconducted by Golder

Controlled blastingrecommended byGolder Associates

Prior to currentmine plan

Development of the465-944 DRE andXcuts in the early

1990s

About 01/10/1999

Lost cutter head in465 - 743 LCH

Intersected badground

Bad ground wasfound in crosscuts

Concreted cutter headin place to form plug

1m advance with roadheader, then shotcrete

immediately

Managementteam remained

Conventional Drill andBlast used in 944 DRE,

Roadheader in crosscuts

Ground conditions inxcuts were like mud

Validation of minedesign

Cable bolts in allintersections also

recommended

Ground supportconsisted of steelsets and shotcrete

Development on465m level halted

"Controlled blasting and carefulcontrolled excavation approacheswill need to be adopted in areas

of poor rock quality."

Mine Design ValidationStudy for the Cigar Lake

Mine, March 22, 2002

A B

Approximately 40m3/hr inflow

of 96 77

22/09/2006

Began developmenton the 465-944 drift,

blasted 1st round

About 28/02/2006

Audit of inflowpotential completed

by E & P

Requested by VP Miningas a result of Mc River

inflow in 2003

Recommendations madeto take special precautions

if mining 465 drift

No formal dispositioning ofFeb, 2006 Audit

Recommendations on waterrisks at Cigar Lake

Construction on 465-944 DREdrift was started prior to

having adequate emergencywater pumping & treatment

systems in place

07/12/2005

Email fromConstruction Mgr. to

MTM re: Groundsupport efforts

Ground supportinstallation not

meeting time specs

Inadequate MTM manpowerto meet requirements linked

to contract specs

Ventilation system restrictsequipment use, resulting in

prioritization of tasks

MTM began to installshotcrete 84 hours after 1st

round blastedMine scheduling performedday to day. Emphasis on

surface construction

Mine development in severalareas resulted in the need to

juggle priorities andresources

Audit report distributionlimited, site management

did not recognize thewarnings

Management believed thereport applied to post

construction, not development

Plan was to upgrade emergencypumping & treating capability to

1,500 m3/hr as per lessonslearned from McArthur River inflow

B C

CF#1

of 96 78

28/09/2006

Geotechnical auditconducted by E&P

Report stressedimportance of

expediance of groundcontrol in general

28/09/2006

Drilled/blast 2ndround in 465-944,

including turnout onsouth side of drift

MTM began to installshotcrete 84 hours after

2nd round blasted

03/10/2006

Drilled/blast 3rdround in 465-944


3rd round blasted

Time requirementsunderstood by Area

Coordinator to be guidelinerather than a requirement

72 hour time requirement wasnegotiated between Cameco andMTM as reasonable rather thantechnically ideal. Intended as a

requirement not guideline

Geology dept priorities weredirected towards freeze holeprogram. Less priority on or

demand for mapping

Others indicated the timerequirements were specs,

not guidelines

Prescribed groundsupport was consistent

with RM2/3

C D

of 96 79

07/10/2006

Drilled/blast 4thround in 465-944

The Engineered Mine Plan for thisintersection was not sufficientlyconservative given the geology

encountered, the existing resourcesand conflicting priorities at Cigar Lake

5 m cable bolts in intersectionsconsistently recommended by

Golder Associates

Detailed mine plans made noreference to extra support for

intersections or 5 m cable bolts


4th round blasted

Cameco decision makers at CigarLake were extremely sensitive to

being in close proximity to theunconformity and felt 5 m cablebolts were not a realistic option

Expert opinions conclude that, underideal conditions, the specified groundsupport could have been adequate forthis intersection. However, a factor of

safety is compromised withoutadditional ground control measures

(such as 5 m cable bolts)

Ideal conditions are not the norm.There is variation in the geology for

this area, over-excavating the drift andtimeliness of applying ground support

Several MTM personnel (and oneMining Engineer) interviewed

were unaware that the 944 DREdrift was close to the unconformity

D E

5 m spiling and additionalmeasures were specified on

drawings as additional support.

Past experience in 944 DRE didnot indicate problems with

ground support in intersections

CF#2

Cigar Lake personnel rejected the5 m cable bolt recommendationdue to the risk of intersecting the

unconformity

No equivalent ground controlmethod was considered

According to PBQDrecommendations, cable boltswould not be required for theintersection where the fall of

ground occurred

of 96 80

11/10/2006 6:00 AM

MTM drilled/blasted465-773 LCH

intersection slash(5th round)

MTM slashed the cross cut using ajumbo drill and intersected unknowngeology. The slashing round created

a larger opening than specified inthe Engineered Mine Plan

Mining Engineering indicate thatthe intent was to drill LCH's with abolter/jackleg rather than a jumbo

to control over excavation

Separate driving layouts for 944DRE & 773 LCH may have created

confusion over requirements

Nothing on the driving layoutsto indicate that a jackleg must

be used to drill the LCH's

A significantly larger span than theEngineered Mine Plan called for

was excavated at the 465-944 DREand 465-773 LCH intersection

Immediately prior to the ground fall,two high angled faults were identifiedin the 773 LCH/XCN. At least one of

these could have been identifiedprior to blasting round #5

Geology do not consistently do detailedmapping in development areas. Theyhave primarily relied on core samples

from diamond drill holes to tell them whatground conditions to expect

Historically, geological mappinghas not been a priority in the

development sequence.

Consultant recommendations identifythe importance of detailed geological

mapping in variable ground

Consultant recommendationsand the detailed mine planscall for "controlled b lastingtechniques to be used."

There remains a question as towhether and how consistently

controlled blasting was carried out

"Controlled b lasting and carefulcontrolled excavation approacheswill need to be adopted in areas

of poor rock quality."

Golder Associates Mine DesignValidation Study for the CigarLake Mine, March 22, 2002

There are no "controlled blasting"procedures in place. MTM have a

blasting procedure that addressesperimeter hole requirements

E F

CF#3Span was surveyed at 10

metres. Should have been nomore than 7 metres

Identification of the fault prior totaking round #5 would likely have

changed the approach to drilling &blasting the 773 LCH

of 96 81

15/10/2006 4:00 PM

Underground inspectionindicates ground support install

only 25% complete (106 hrs)

Detailed Driving Layoutrequirement of 72 hours forinstallation of ground control

surpassed

Loading pocket/rockbreaker not working,

contributed to delays inmucking the area

The specified groundsupport was not applied in a

timely manner

An October 15th non-conformance reportfrom Mine Engineering indicates that 106

hours had passed with only 25% of requiredbolts being in place and no shotcrete

Going beyond the 72 hour specification wastypical in the 944 drift and some key

personnel understood that the 72 hour figurewas a guideline and not a requirement

It is MTM's perception that Camecoprioritize and drive their activities.From their perspective, priority in

944 DRE was not very high

Driving layouts specifycomplete ground support to be

in place within 72 hours

F G

CF#4

of 96 82

19/10/2006

MTM noticed spalling ofshot crete in the area

As a result of therock movement

17/10/2006 9:00 AM

Bolting completed in465-773 LCH.

Shotcrete beingapplied

East pillar of LCHundercut 1.5m

Visible loose rockwhere shotcrete fell

Soft ground and bigblocks fell from the

face in 773 LCH

MTM began to installshotcrete 144 hours

after 5th round blasted

Evidence of large wedgerequiring deep support

Shotcrete application notalways of good quality, no

QC of installation done

No mapping of the 773 till now,thus wedge went unidentified

and therefore unsupported for aprolonged period of time

18/10/2006

Blasted in 773 LCHto square the face

10 holes at 3 meters, 2cases of stick used

(describe stick)

G H

of 96 83

20/10/2006

MTM modified groundsupport requirementswith input from E&P

Standard length ofrock bolts 2.4m and

use of straps

Rock bolt length limited bydistance to unconformity

21/10/2006

Installion of strapsand bolts completed

About 22/10/2006 10:00 AM

More spalling of shotcrete and indications ofrock movement, areacoordinator contacted

Rock boltsproducing smallamounts of water

Benched material placed for rockbolting may have concealed actual

extent of the unsupported span

Corp rock mechanics engineerrecommended 5m rock bolts

for best support, but wasrejected by Chief Engineer due

to proximity to unconformity

Strapping installed at greaterthan 1 m intervals, accepted

by senior engineer

Some bolts installed into verysoft ground. Bolter indicates he

could push bolts into groundwithout drilling.

H I

of 96 84

Estimated to beapproximately 340 m3/hr

Underground pumpingcapacity at the mine was

500 m3/hr

22/10/2006 11:00 AM

Area Coordinatorsees evidence ofground movement

over large area

No noticable stress onground support but lotsof cracking of shotcrete

in the area

Limited access tothe area

22/11/2006 11:30 PM

Area coordinatorrequested an

emergency conferencecall for 01:00 hours

Decided to construct atemporary bulk head and

plug the area with concrete

Was same practiceas for the 807 area

About 22/10/2006 12:00 PM

Fall of groundoccurred,

accompanied by alarge inflow of water

Area Coordinator stated that "Iknew the back was coming down.

It was just a question of when."

I J

of 96 85

Decided to install atemporary concreteplug on 465 level

Idea is to stem water flowto allow construction of apermanent concrete plug

Permanent plug tobe constructed oncewater was contained

22/10/2006 1:10 PM

Crisis teamformed at Headoffice and site

HR Sup't asks ifbulkhead doors shouldbe prepared for closure

HR Sup't requests forprocedure to be available

for door closure

Used sandbags and pipesto create dry section of

tunnel for construction ofthe concrete plug.

Water leveldecreasing in shaft 2

About 22/10/2006 2:10 PM

GM communicates"make sure east andwest BH doors are

free and ready to go"

Began fast trackingemergency pumping

capacity

Theoretical pumpingcapacity of approximately

500m3/hr

J K

of 96 86

About 22/10/2006 4:00 PM

Flow rate was estimatedto have increased tobetween 1,400 and

1,500 m3/hr

About 22/10/2006 7:00 PM

Managementmembers left

Saskatoon to fly tosite

A visual inspectionof the water control

bulkhead doorswas completed

To verify thecondition of the

gaskets

About 22/10/2006 8:50 PM

Message received bypilots that site needed tocommunicate with GM

on the plane

Based on current storagecapacity and water inflow rate

Site personnel believed theefforts should be focused onpreparing to close the water

control bulkhead doors

Water flow increased dueto erosion of loose material

Monitoring of waterlevels and flow

conducted hourly

Net water gain in mine wasabout 1000 m3/hr

K L

of 96 87

22/10/2006 8:51 PM

Head of Command Centreinstructed the site personnelto abandon plug constructionand prepare bulk head doors

for closure

In preparation for closing doors,electrical, service water, drain

water and compressed airservices in the bulkhead must first

be removed and sealed usingpreinstalled valves or blanks

Underground contractorswere salvaging equipmentand instrumentation fromareas north of the water

control doors

Construction of the temporary plugrequired the services which ran

through the doors, thus the doorscould not be prepped for closure atthe same time as plug construction

There was no sense ofurgency at this time by

Area Coordinator

Wanted to preserveequipment then close doors,so delayed closing of doors to

salvage equipment

Prepping doorsbegan

Considered blankingoff some pipes rather

than using valves

Valves were not functioningas intended due to corrosionand shotcrete. Valves neverclosed since installed (not

part of door PM)

Experiencedproblems finding

appropriate blanks

Sump area behind westdoor required cleaning with

excavator and air lance

Temporary construction hadbeen taking place with some

effort towards the door

Due to stable water flow, thislikely did not factor in to the

doors failing

L M

After order given to abandonplug construction, efforts

changed towards preparingthe doors for closing

No indication that thedoors would not sealwhen finally closed

of 96 88

Three electriciansproceeded to 465 MCC

room to begin removingelectrical equipment

Airborne radiation hadincreased at the MCCfrom 0.3 WL to 13 WL

About 23/10/2006 4:25 AM

All the services removedfrom the bulkheads

housing the doors and thevalves were closed

Took 7hrs and 25 minutesto prepare doors, initiallythought approx 2 hours

Af ter 23/11/2006 1:07 AM

Mine was swept toensure all personnelwere accounted for

prior to closing doors

Formal Proceduredeveloped to ensure all

personnel were accountedfor when the doors were

finally closed.

5 people with SCBA,scarried out mine sweep,

led by Safety officer

Delay caused by salvagingof equipment and valve

issues on bulkhead doors

Guards posted atdoors to monitor traffic

Accompanied by aradiation technician

All accounted for andremoved from north

side of mine by 2:30 AM

M N

Mine sweeping describedby several interviewers asprofessional and effective

Design intent was for the 12inch valves to be open when

doors are closed

of 96 89

23/11/2006 4:25 AM

Head of CommandCentre gave the

instruction to closethe doors

23/10/2006 4:58 AM

MTM closed the EastDoor

Water level was roughly12 inches deep flowing

through the door

About 23/10/2006 5:10 AM

MTM closed the WestDoor

Swung nicely but didnot square as needed

No water flowing at this time

Problems with dooralignment while closing,

leveraged into place

Formed a tight sealwith little to no leakage

Gasket replaced a year ago afterit failed test. Gasket taken from420 level door and installed on

East Door.

Double hinge doordesign made it difficult to

square the door

Gasket glue may havebeen in better condition

than on West Door

The initial attempt to close the WestDoor was not completed in dry

conditions as specified in the design

There is no mechanism, otherthan manual manipulation, for

easily squaring doors

N O

This required pushing it openand a second closing attempt

against a now rising water level

CF#5

of 96 90

Upon adjusting and closingthe West Door, a section ofgasket separated from the

door flange, resulting in waterflow through the door

Gasket comprised of 4sections, each section

roughly 11' in length

Water level now at 6"going through

bulkheadInitially estimated theleakage through the

door at 200m3/hr

Design of the bulkheads expose thebottom of the doors to constant watersubmersion, may have compromisedthe integrity of the door seal adhesive.

23/10/2006 5:32 AM

MTM opened WestDoor with LHD toadjust alignment

Increasing water flow as thearea behind east door filledto the point that water would

flow to the West Door

About 23/10/2006 6:00 AM

MTM attempted toclose the WestDoor for the 2nd

time

Connected by one side,other side hanging into

bulkhead, 3/16" gap

May have been dislodgedby water flow while

closing the doorWitnessed and reported toCommand Centre by Mine

Superintendent

No hanging gasketobserved at this time

Crew was unable toestablish a water tightseal around the door

O P

CF#6

of 96 91

23/10/2006 6:16 AM

MTM Supervisor instructedto try reinserting gasketmaterial into door rather

than pump concrete

23/10/2006 8:10 AM

MTM pushed door openslightly using a load haul

dump unit (LHD) in anattempt to insert the

packing material

Load Haul Dump(LHD) used to pushand pull door into

position

Would need toreopen the door tocomplete the task

U/G crew instructed toopen door, reinstall

gasket or attempt to useother gasket material

22/10/2006 6:45 AM

Area Coordinatorsent u/g to

coordinate efforts

Initial plan of U/Gcrew was to pump

concrete behind doorvia pipes in BH

Believed aggregate wouldrestrict flow. Had past

experience and successwith this approach

MTM Supervisor atdoor did not want tore-open door with

water building behind

Idea was supported byMine Superintendantpresent at the door

Needed to firstsource some gasket

material

Dayshift crew comingon shift. Changeover

of workers at thedoors occurred

Water up about 12inches on door at

this pointIdea was communicated tothe Head of the Command

Centre but rejected

Carried gasketmaterial with him

The decision to force theWest Door open at 08:10hours to repair the gasketled to an increased flow

through the door

Area Coordinator took ameasurement of the flowrate

coming through the westdoor after the 08:10 opening

Flowrate estimates of 115to 200 m3/hr through thewest door between 06:00

and 08:00 hours

CF#7

P Q

Flowrate worse after the08:10 door opening.

Calculated to be 800 m3/hrHead of the CommandCentre believed gasket was

essential to establish aneffective seal

of 96 92

23/10/2006 8:10 AM

MTM closed door

Due to the intensewater spray caused by

opening the door

Af ter 23/10/2006 8:15 AM

Proposal made toinsert burlap throughpipes in an attempt to

seal leak

LHD operator stungby spray through door

Would then groutbehind bulkhead door

and support thegasket

Agreed upon by Headof Command Centreand Area Coordinator

Material for attempt(burlap/grout) being

sourced on site

Had problems findinggrout, needed Boart to

help with grouting

No grout at shaft #1as expected

23/10/2006 9:45 AM

Cage was lost

Water level interferingwith instrumentation

at bottom of shaft

Bypassedinstrumentation to

run cage

Door slammed shut whenLHD backed away

Because of concave shapeof door, workers could not

gain access to attemptreinserting gasket material

Cigar Lake pumpingcapacity is roughly

500 m3/hr

Q R

of 96 93

Water level behind thewest door approximatelyfour feet above the floor

Piping through theupper part of the

bulkhead was still dry

While preparing for burlap &grout attempt, Head of

Command Centre instructed toopen door a minimum of 2 feet

and attempt to insert gasket

Area Coodinator did notagree, but was

instructed by Head ofCommand Centre to

complete the task

Burlap and grout ideawas not implemented

22/10/2006 9:54 AM

Cage back inoperation

Could move at 200ft/min (1200 typical)

About 10:35 AM

U/G Crew openeddoor at least 2 feet,

large inflow occurred

MTM supervisor noticedthat electrical pumps willbe lost if door not closed

immediately

2-1/2 hours had passedsince last door opening

LHD Operatorattempted to closedoor but could not

Floating object had beencaught in the door at the

3:00 o'clock position

WL's now above 10so required SCBAfor further attempts

The decision to force the WestDoor open at 10:35 hours to

repair the gasket led to debrisbeing caught in the door which

caused a significantly increasedflow through the door

Instructed by Head ofCommand Centre to let

water levels equilize for afew minutes and then

attempt to insert gasket

Area Coordinatorcommunicated status to

Command Centre

MTM Supervisor respondedto door on bobcat up to chest

in water (sitting in seat)

All agreed that one finalattempt to close door was

necessary

Lots of floating materialcoming through the

West Door

Flowrate through theWest Door was now toohigh for any other option

to be considered

CF#8

R S

of 96 94

Ventilation at WestDoor became

insufficient

Wanted to changeventilation to area to

reduce WL's

Decided to tackle doorissue prior to ventilationto reduce conventional

risk to crew at door

5 man MTM crew inSCBA assigned to

attempt door closure

Instructed to tie piece of rope toobject pinched in door, opendoor slightly and tug object

3 man MTM crewpush open the WestDoor using scoop

Two workers at door couldnot withstand the flow. Struck

with large debris. Watercoming over shoulders

High water volume through doorcreated pressure on the

backside of the door

LHD had limited traction whileattempting to close door

against pressure created bythe water flow

Thus resulting in redprisms and elevated WL's

Once open, the doornot able to be closed

Forcing the door open further thanintended at 11:09 hours resulted in

the door being left open

CF#9

S T

This forced the door openfurther than intended

of 96 95

LHD broke allstraps/ties to the door

(1/4 inch wire rope)

MTM employeesevacuated the door

area

One member lost footingfrom water flow, regained

footing and went tonearby incline

LHD Operator jumped fromLHD and was helped to the

incline by the others

U/G Area Coordinatordecided to evacuate

Water was describedas being extremely cold

23/10/2006 11:14 AM

U/G Area Coordinator reportedsituation to Command Centre.

Head of Command Centreagreed to evacuate mine

Water 3 to 4 feet deep at thecage level doors. This made

it difficult to walk

Af ter 23/10/2006 11:14 AM

U/G Area Coordinatorcalled for cage

Too much waterflowing into shaft at

480 level

T U

Cage could not get intoposition at 480 level

of 96 96

Hoist Operatorstaged the cage justabove the 480 level

access

Extra care required inentering the cage

21 workers at 480level climbed into the

cage

Three people on 420Lwere monitoringpumping station

No certain method ofknowing if all had beenaccounted for until theytagged out on surface

Skip full of waterbelow cage

Cage stopped at 420level to get 3 other

workers

Lost visualcommunications to

hoist room just prior tosignal to go up

Left a 1 foot gap to getinto cage from ladder

24 people u/g at the finaldoor opening

23/10/2006 11:30 AM

Cage reachedsurface and servicesshut off to the mine

Miners soaked fromefforts

Were instructed to tagout and hand in all

radiation monitoringdevices

Radiation monitoringdevice placed at shaft

collar

U

Workers used ladderto access cage

Still had the standardaudio signals

Exceeded occupancylimit by 3 workers but

well within hoisting limit

V

V Mine Floods

taproot investigative report - 23 april 2007€¦ · the october incident taproot® report...

Documents