November, 2013 TH 53 Realignment: E-1A Preliminary RSS Design GALE-TEC ENGINEERING, INC/Dr. B.R. Christopher November, 2013 Gale-Tec Engineering, Inc.

E-1A Alignment E-1A Alignment Gale-Tec Engineering, Inc. City of Virginia UTAC Thunderbird Mine Pit Existing TH 53 Old Rouchleau Mine Pit

E-1A Alignment E-1A Alignment Gale-Tec Engineering, Inc.

E-1A Alignment E-1A Alignment Gale-Tec Engineering, Inc.

E-1A Alignment E-1A Alignment Gale-Tec Engineering, Inc.

E-1A Alignment E-1A Alignment Gale-Tec Engineering, Inc.

E-1A Alignment E-1A Alignment Gale-Tec Engineering, Inc.

E-1A Alignment E-1A Alignment Gale-Tec Engineering, Inc. Rouchleau Pit City of Virginia Roadway Profile 130 – 170ft ~ 2800ft

E-1A Alignment E-1A Alignment Submerged Haul Road Embankment – Topo Map Gale-Tec Engineering, Inc. Haul Road Embankment Highwalls (80ft) ~520ft

E-1A Alignment Submerged Haul Road Embankment 2013 MnDOT Drilling/Resistivity Study 40 – 120ft Mine Waste Rock Boulders/Cobbles over Cherty Bedrock Gale-Tec Engineering, Inc.

E-1A Alignment Submerged Haul Road Embankment Gale-Tec Engineering, Inc. Results of Resistivity Study Recovered Core Samples from Drilling

E-1A Alignment Roadway Embankment Footprint 3H:1V Side slopes will create a Roadway Embankment Footprint about 1100ft wide 1H:1V Sideslopes reduce Footprint Width to 450ft 1H:1V Sideslopes requried to fit Roadway Embankment on Submerged Mine Haul Road Gale-Tec Engineering, Inc.

E-1A Alignment Why are Reinforced Soil Slopes Required ? Reduce Embankment Footprint Submerged Haul Road Embankment only 500ft Wide Reinforce Embankment from Seismic Forces Caused by Mine Blasting Events Less Fill Material Required For Embankment Gale-Tec Engineering, Inc.

E-1A Alignment Roadway Embankment Footprint 1H:1V Embankment Side Slopes Gale-Tec Engineering, Inc.

E-1A Alignment Roadway Embankment –Fill Quantities Embankment with 3H:1V Side slopes : >10 Mil CY Fill Embankment with 1H:1V Side slopes : 4 Mil. CY Fill Gale-Tec Engineering, Inc.

E-1A Alignment Roadway Embankment Design Seismic Forces Mine Blasting induces Seismic Forces Acting on Embankment HDR/Revey Assoc. Study of UTAC Thunderbird Pit in 2012 HDR/Revey Assoc. Study indicates PPAmax = 0.3g Gale-Tec Engineering, Inc.

E-1A Alignment Roadway Embankment Design Stability Analysis Need to Reinforce Both Embankment Sideslopes so Back-to Back RSS Embankment is Required Seismic Stability Governs Design – Horizontal Seismic force of 0.3g added to each slice during Stability Analysis Vary Geogrid Strength, Vertical Increment, Horizontal Length until Adequate Seismic Factor of Safety (1.1) Obtained With Seismic FS = 1.1, Static FS = 2.5 Gale-Tec Engineering, Inc.

E-1A Alignment Roadway Embankment Design Stability Analysis – Typical Section Gale-Tec Engineering, Inc.

E-1A Alignment Roadway Embankment Design Seismic Stability Analysis - Results Gale-Tec Engineering, Inc. Direct Sliding Global Stability w/Highwall

E-1A Alignment Roadway Embankment Design Questions? Gale-Tec Engineering, Inc.