1. Customer Meeting April 28, 2010 Torrington, WY

2. Agenda Introductions Accomplishments Update on Torrington Area PVVC Overview PVVC Schedule and Cost Estimates Questions/Comments Wrap Up

3. Accomplishments since 2003 Whiterock Substation (2005) Lingle Tap (2003) Lyman-Yoder Tap (2005) McGrew area Caps (2005) Stored mobile transformer at Guernsey Rural (2004) Wood Pole Testing and Treatment (2003 & 2004) Letter of Concurrence between Tri-State and Western on Platte Valley conversion project (2005) Glendo Substation Relay System & RTU replacement

4. Accomplishment since 2003 Gering Station Service Switchgear (2006) Gering PCBs 162, 462, 966 replacement (2006) Glendo PCB 524 (2006) Limestone additions (PCB 442, new control & relay system, new RTU) (2009) Repaired Mobile transformer and returned to Guernsey Rural (2009)

5. Upcoming Projects (2008-2011) Torrington transformer KY2A addition (In-service May 2010) Gering-Gering Valley 34.5-kV rebuild (2011)

6. Torrington KY2A addition Project to add 115/34.5-kV 50 MVA transformer Joint project with City of Torrington Transformer delivered - Oct 2008 Construction contractor complete – Dec 2008 Control Design & switchboard delivered Commissioning ongoing

7. Platte Valley Voltage Conversion The objective of the Platte Valley Voltage Conversion Project is to convert the operating voltage of the 34.5- kV transmission lines and related facilities between Lingle Substation and Sievers Rural Substation to 69- kV. The lines were rebuilt in the early 90’s to 69-kV standard.

8. Platte Valley Voltage Conversion The majority of the work is converting the numerous substations and taps along the line segments to 69-kV. Western and Tri-State signed a Letter of Concurrence in November 2004 laying the initial scope and responsibilities for the upgrades.

9. Platte Valley Voltage Conversion Scope: Lingle Substation: Install a 115/69-kV 40 MVA transformer and associated equipment. Torrington Substation: Install a 69/34.5-kV 50 MVA transformer and associated equipment. Sievers Rural Tap: Install a 69/34.5-kV 25 MVA transformer and associated equipment. Construct eleven miles of new 69-kV line between East Morrill Tap and Sievers Rural Tap.

10. Platte Valley Voltage Conversion Scope (cont): Torrington Rural Tap: Replace transformer and rebuild high side for 69-kV. Henry Tap: Replace transformer and rebuild high side for 69-kV. Village of Morrill Tap: Make necessary modifications to operate existing dual winding transformer at 69-kV. Connect the Town of Lingle Tap to the Limestone-Lingle 34.5-kV line.

11. Platte Valley Voltage Conversion Scope (cont): Estimated Cost: $21M Planned ISD: FY2015 Project Manager: Roy Gearhart Current Status: Not planned to start until FY2012. System Studies updated every two years. System Studies planned for 2010.

12. Platte Valley Voltage Conversion Major Milestones to date Various System Studies: 2000-2010 Meeting with Platte Valley Customers: April 2003 Western and Tri-State signed Ltr of Concurrence: November 2004 Meeting with Platte Valley Customers: April 2005 Meeting with Platte Valley Customers: April 2007 Published Platte Valley Voltage Conversion Project Overview: January 23, 2006

13. Platte Valley Voltage Conversion Lingle Substation Scope: 115kV/69kV 40MVA transformer with high and low side interrupters for protection. New Substation site required for 115/69kV additions New Control Building Schedule: 2012-2015 Estimate: $4,730k (In 2014 $’s)

14. Platte Valley Voltage Conversion Lingle Town Scope: Move connection to Limestone 34.5-kV line with ~0.5 mile of new 34.5-kV line. Schedule: 2012-2015 Estimate: $100k - $200k (no detail estimate done)

15. Platte Valley Voltage Conversion Torrington Rural Scope: Convert to 69-kV with a 69kV/12.47kV 5MVA and a 69kV/24.9kV 7.5MVA transformers and 69kV improvements on high side. Schedule: 2012-2015 Estimate: $1,500k (In 2014 $’s)

16. Platte Valley Voltage Conversion Torrington Substation Scope: New 69-kV yard with 4–69kV bays; 69kV/34.5kV 50MVA Transformer; New Control Building; more land. Schedule: 2012-2015 Estimate: $5,400k (In 2014 $’s)

17. Platte Valley Voltage Conversion Henry Scope: Convert to 69-kV with a 69kV/12.47kV 7.5MVA transformer and 69kV improvements on high side. Schedule: 2012-2015 Estimate: $900k (In 2014 $’s)

18. Platte Valley Voltage Conversion Village of Morrill Scope: Convert to 69-kV high side winding on existing 34.5/69/7.2/12.47kV 2.5MVA transformer and 69kV improvements on high side. Schedule: 2012-2015 Estimate: No estimate done

19. Platte Valley Voltage Conversion East Morrill Tap – Wildcat 69-kV line Scope: Construct ~3 miles of new 69-kV line from East Morrill tap to Wildcat. Creates the Lyman-Wildcat 34.5-kV line. Allows Village of Lyman and Lyman Rural loads to remain 34.5-kV Schedule: 2012-2015 Estimate: $1,395k (in 2012 $’s)

20. Platte Valley Voltage Conversion Wildcat Substation Scope: No new additions initially planned at Wildcat. Should the system needs change, the new Torrington-Sievers Rural 69- kV line could be interconnected with the 34.5-kV system at Wildcat to provide system reliability improvements.

21. Platte Valley Voltage Conversion Wildcat-Sievers Rural 69-kV line Scope: Construct a new 10 mile 69-kV line between Wildcat and Sievers Rural to bypass Mitchell area. Bypasses City of Mitchell and Mitchell Rural loads, leaving them at 34.5-kV Schedule: 2012-2015 Estimate: $4,045K

22. Platte Valley Voltage Conversion Sievers Rural Scope: 69/34.5kV 20 MVA transformer with high and low side protection; new control building; land. Sievers Rural load remains served at 34.5-kV. Schedule: 2012-2015 Estimate: $2,250k (In 2014 $’s)

23. Wrap Up Questions or Comments?

24. Thank You Contacts Bob Easton (Western) 970-461-7272 or aeaston@wapa.gov Roy Gearhart (Western) 970-461-7333 or rgearhar@wapa.gov Stan Lawrenson (Tri-State) 303-254-3452 or slawrenson@tristategt.orgslawrenson@tristategt.org