A presentation on Partial Pit Backfill Alternative associated with the Rosemont Copper Project Operations. This presentation was given by Rosemont Copper to the Forest Service, the Cooperating Agencies, and their contractors during a meeting in January 2010.

1. Partial Backfill
Alternative
January 21, 2010
Cooperator’s Meeting Presentation

2. Partial Backfill Alternative
Considerations
• Be responsive to an Issue
• Minimize water that collects in the pit
• Return waste rock to the pit
• Minimize resources that are used in
backfilling
• Minimize air impacts

3. Partial Backfill Alternative
Environmental Considerations
• Compliance with all applicable regulations
including ADEQ BADCT and air regulations
• Maintain a Hydraulic Sink
• Geochemical considerations with the addition of
a mix of finer grained materials
• Stormwater controls during backfill
• Effect on concurrent reclamation and on
reclamation planning

4. Pit Lake Development

5. Hydrogeologic Study Results
Pit Lake
Pit Lake Depth
Period Elevation
(feet)
(ft amsl)
Mine Closure (None) 0
Closure + 20 years 3,591 541
Closure + 50 years 3,751 701
Closure + 100 years 3,869 819
• Backfill elevation – 3825 ft amsl (est.)
• Elevation was estimated to maintain sink (modeling to confirm
elevation estimation with operational adjustments as necessary)

6. Other Considerations
• Heap Leach remains undisturbed
• Haulage fleet used will be consistent in size
to current fleet
• Loading equipment (shovel used will
be consistent with current loading
equipment)
• Waste rock density is 11.95 ft3/ton
• Swell factor for the rock is 1.3

7. Other Considerations
• Amount of material necessary for backfill is
90 million tons (46 million cubic yards)
• Allowance of 5% added for construction of
ramps for downhill haulage
• Total material rehandled 94 million tons
• 36-months required to complete backfill
• Hauls will incorporate 3 switchbacks at
-10% grade at a maximum 13 mph

8. Backfill and
Excavation Area
• Excavation on 50 foot
benches
• Start elevation approx
5429 ft amsl
• Final elevation 5200
ft amsl
• Dumped into pit from
3825 ft elevation

9. Productivity by Bench
Bench
Tonnage
Cumula+ve
Haulage
Eleva+on
(x
1,000)
Tonnage
Produc+on
(.
amsl)
(x
1,000)
(tons/hour)
5420 8,938 8,938 379
5400 18,435 27,373 387
5350 18,689 46,062 395
5300 16,277 62,338 403
5250 12,977 75,315 411
5200 8,720 84,036 419
This information was used to determine the appropriate
haulage fleet for this activity matched to one shovel.

10. Required Haulage Hours and Units
Rehandle
CAT
793C
Truck
Fleet
Post-­‐Mining
Tons
Year
Opera+ng
(x
1,000)
Units
Hours
1 28,774 74,740 16
2 28,853 72,439 16
3 26,409 64,021 15
Total 84,036 211,201 16
Modeling indicates that 16 trucks will be required in the
first 19 months of the project and 15 for the remainder.