Comparison of Quality of Estimate Classes* Item Class 5 Class 4 Class 3 Class 2 Class 1 Aurecon’sClassification Concept Pre-feasibility Bankable

Feasibility Implementation – Basic

Implementation – Definitive

Also known as: Order of Magnitude Est. Preliminary Estimate Control Budget Estimate Definitive Estimate Detailed/Fair cost Est. End Use (Typical purpose of estimate) Concept Screening or

feasibility; Comparison of alternatives; Prelim. Investigation

Concept Study or Feasibility; identify data required & cost of Class 3 Estimate

Budget, Authorisation or Control; Project Approval; Provide basis for securing finance

Control or Bid/Tender; Detailed control baseline for monitoring Variation to budget

Check Estimate or Bid/Tender – typically against discreet parts of total project

Methodology Capacity factored, parametric models, judgment or analogy

Equipment factored or parametric models

Semi-detailed unit costs with assembly level line items

Detailed unit costs with forced detailed take-off

Detailed unit cost with detailed take-off

Level of Engineering Definition 0% to 2% 1% to 15% 10% to 40% 30% to 70% 50% to 100% Risk Profiling & Contingencies Up to 30% Up to 25% Up to 15% Up to 10% Up to 7% Indicative Probability Range Not greater than 90% Not greater than 90% Not greater than 90% Not greater than 90% Not greater than 90% Accuracy - Indicative Range High +30% to +100% +20% to +50% +10% to +30% +5% to +20% +3% to +15%

Low -20% to –50% -15% to –30% -10% to –20% -5% to –15% -3% to –10%

BASIS OF CAPITAL COST ESTIMATES Site Location Assumed Preliminary Optimal Final Final Maps and Surveys None Preliminary Some detail Detail Detail Soil Tests & Geotechnical None Prelim Final Final Final Site Visits Not essential Desirable Essential Essential Construction Commenced Construction Support Assumed Proposed method Detail support Final Final Construction site Agreement Assumed Assumed Prelim discussion Final Final / In Place Delivery Strategy Assumed Preliminary Initial Strategy Specific Specific Mining Site Visits Desirable Essential Essential Frequent Frequent Maps and Surveys Required Good quality Detailed Detailed Detailed Drilling Exploration Exploration Delineation Grade control Grade control Resource Estimate Indicative Probable Measured/ Indicated Measured Measured Reserve Estimate Indicative Indicative Proven / Probable Proven Proven Mining method Assumed Preliminary Optimised Finalised Finalised Mining schedule By analogy Preliminary Detailed Finalised Finalised Mine Geotechnical & Hydrology Assumed Preliminary Detailed Finalised Finalised Equipment selection Not essential Preliminary Type and capacity Make and model Make and model Process Plant Capacity Assumed Preliminary Final Final Final Ore Samples Available samples Representative samples Representative samples Actual Actual Metallurgical Testwork Commenced Advanced Completed Completed Completed Pilot plant Identify need and

specify bulk sample Commenced, some results available

All results available Finalised Finalised

Energy & Material Bal. Estimated Advanced Optimised Final Final Process Flowsheet Assumed Preliminary Optimised Final Final Design Scope of Estimate Concept Probable Actual Actual Actual Equipment Selection Assumed Preliminary Optimal Optimal Final GA - Mechanical None Minimum Fair detail Complete Complete GA - Structural None Outline Fair detail Complete Complete Piping Drawings None Single-line Some detail Advanced Advanced Electrical Drawings None Single-line Some detail Advanced Advanced Detailed Design Drawings None None Some detail Draft Mostly Complete Specifications None Preliminary Advanced Mostly Complete Mostly Complete

CAPITAL COST ESTIMATE Infrastructure costs: Power, Water, Roads, Rail

Assumed Investigated Finalise Detail Finalised Finalised

General Cost Approach Factored block costs where possible

Preliminary Quantity Detail Quantity Detail /Actual Quantity Detail /Actual Quantity

Major Equipment Costs Data bank / Factored Single source Multiple source Fixed tender Fixed tender Civil Work Rough quantity Preliminary Take-off Take-off Tender Prices Structural Work $/unit vol. Prelim take-off Take-off Take-off Tender Prices Piping & Instrumentation % Machinery Prelim take-off / % Take-off Take-off Tender Prices Electrical $/kW Prelim take-off Take-off Detailed Estimates Detailed Estimates Installation Factored / % Man-hours / unit rates Man-Hours Man-Hours / Contract Man-Hours / Contract Indirect Costs % of total Prelim calculation Calculation Detail calculation Detail calculation Spare Parts % of total % of total % of total % of total Substantially Complete

OPERATING COST DETERMINATION Staffing Levels Factored Preliminary Detailed Estimate Known Known Labour costs Factored Calculated Known Basis Known Known Admin/Management cost eg insurance, taxes, duties etc

Factored Preliminary Final Final Final

Power costs Factored Quoted Estimated Known Known Fuel costs Factored Quoted Estimated Known Known Consumable supplies Factored Factored Estimated Known Known Reagents Factored Factored Estimated Known Known Maintenance Supplies Factored Factored Estimated Known Known

*Estimates are classified in accordance with AACE Practices

Estimates are classified in accordance with AACE Practices.

Implementation Aurecon’s Classification

Concept Pre-Feasibility Bankable Feasibility Basic Definitive

AACE ESTIMATE CLASS

Class 5 Class 4 Class 3 Class 2 Class 1

LEVEL OF DEFINITION Expressed as % of completed definition

0% to 2% 1% to 15% 10% to 40% 30% to 70% 50% to 100%

END USAGE Typical purpose of estimate

Concept screening

Study or Feasibility

Budget, Authorisation or

Control

Control or Bid/Tender

Check Estimate or Bid/Tender

METHODOLOGY Typical estimating method

Capacity factored,

parametric models,

judgement or analogy

Equipment factored of parametric

models

Semi-detailed unit costs with assembly level

line items

Detailed unit cost with forced detailed take-off

Detailed unit cost with

detailed take-off

EXPECTED ACCURACY RANGE Typical variation in low and high ranges [a]

Low: -20% to –50%

High: +30% to +100%

Low: -15% to –30%

High: +20% to *50%

Low: -10% to –20%

High: +10% to +30%

Low: -5% to –15%

High: +5% to +20%

Low: -3% to –10%

High: +3% tp +15%

PREPARATION METHOD Typical degree of effort relative to least cost index of 1 [b]

1 2 to 4 3 to 10 4 to 20 5 to 100

Notes: [a] The state of process technology and availability of applicable reference cost data affect the range markedly. The

+/- value represents typical percentage variation of actual costs from the cost estimate after application of contingency (typical at a level of 50% level of confidence) for given scope.

[b] if the range index value of “1” represents 0.005% of project costs, then an index of 100 represents 0.5%. Estimate preparation effort is highly dependent upon the size of the project and the quality of estimating data and tools.

Estimate Classes Estimates are prepared during the development of a project in parallel with the various project development stages. Therefore, estimates are classified as follows:

° Class 5 – Concept or Order of Magnitude Estimate Undertaken to provide preliminary economic evaluation or comparison of alternatives. Used for indication of whether additional study or engineering is warranted. Typically, has a stated accuracy of -30% to +50%.

° Class 4 – Pre-feasibility or Preliminary Estimate Part of the pre-feasibility study. Used for economic evaluation of a project and the basis for positive

rejection of a project. Typically, has a stated accuracy of -15% to +30%. ° Class 3 – Bankable Feasibility or Control Budget Estimate Part of the feasibility study. Suitable for a detailed economic evaluation and will determine the control

budget of a project. Forms the basis for Board approval and funding. Typically, has a stated accuracy of -10% to +20%.

° Class 2 – Basic Implementation or Definitive Estimate Part of the execution phase of a project. Typically, be carried out after 30% to 70% of the engineering is

complete. Incorporates any commercial commitments already in place, any trend estimates either approved or unresolved, and current design quantities and pricing for the unawarded work. Typically, has a stated accuracy of –5 to +15%.

° Class 1 – Definitive Implementation Estimate Part of the execution phase of a project. Typically, engineering is 50 % to 100% complete. Incorporates any

commercial commitments already in place, any trend estimates either approved or unresolved, and current design quantities and pricing for the unawarded work. Typically, has a stated accuracy of –5 to +10%.

Class 1 estimates are generally prepared for discreet parts or sections of the total project and are typically prepared to form a current control estimate to be used as the final control baseline against which all actual costs and resources will now be monitored for variations to the budget, and to form part of the change/variation control programme.