2019-06-28_REVISION - M1977004 ‎(12)‎

• Permit No: M1977004
• IBM Index Class Name: REVISION
• Doc Date: 6/28/2019
• Doc Name: Request For Amendment To Permit
• From: Homestake Mining
• To: DRMS
• Type & Sequence: AM1
• Email Name: DMC
• Email Name: THM
• Media Type: D
• Archive: No

Homestake Mining Company June 17,2019
Regular(112d)Operation Reclamation Permit Application Package
4.0 RECLAMATION COST ESTIMATE
The SRCE model provides a reclamation cost estimate, and is based on the assumptions
presented in the following subsections.
4.1. General Assumptions
4.1.1. Units of Measurement
All units are imperial, unless otherwise noted.
4.1.2. Exchange Rates
Costs are provided in 2018 US dollars (USD$).
4.1.3. Take Off Procedures and Allowances
All earthworks quantities were estimated as neat in place, with an additional 10% allowance for
wastage, swell or compaction of materials.
4.1.4. Factors
Costs presented in the"Cost Summary"worksheet within the SRCE model are undiscounted and
do not include factors for an inflation adjustment or Net Present Value (NPV) discount. These
components have been assigned and incorporated into the costs as part of the "Cost Schedule"
worksheet within the SRCE model, which allows for a distribution of costs over the Closure and
Post Closure periods. An Inflation Rate (i) of 2.0% has been assigned, based on the average
inflation over the last decade. An NPV Discount Rate (r) of 5.0% has been assigned, based on
recent London Interbank Offered Rates (LIBOR) of 3%, plus 2% as a standard for commercial
rates.
4.1.5. Indirect Costs
Indirect Costs are defined as all costs which are required for completion of the construction and/or
installation activities, but are not directly attributed to the cost object. The SRCE model and
corresponding cost data file assign the following rates, based on the total Direct Costs:
• Engineering, Design, and Construction (ED&C) —6% of Direct Costs
• Insurance (1.5% of Labor Costs)
• Bond (3% of Direct Costs)
• Contractor Profit (10% of Direct Costs)
• Contract Administration (8% of Direct Costs).
4.1.6. Schedule
Based on the reclamation activities discussed in Exhibit E (Amended Reclamation Plan), a
reclamation schedule was developed that generally includes the North Pit, South Pit, IRD, TCRD,
Sandstone Quarry, Limestone Quarry, and Haul and Access Roads. Key activities are
summarized below, and the schedule is summarized and presented in Appendix A.
EXHIBIT L-RULE 6.4 12 (RECLAMATION COSTS)(Revised June 17,2019) Page 6
HOMESTAKE MINING COMPANY