20210903PAC to PIIC Attach 77-3 Addendum 5.pdf

PACIFICORP
INTERWEST MINING COMPANY
DEER CREEK MINE MSHA ID NO. 42-00121

Mill Fork Access #2 Mains
Rilda Canyon Portals 1st Right Submains
Proposed Bulkheads – Installation and Monitoring Plan

Addendum #5

Revised Text, Appendices, Figures, Maps and Tables

Addendum Submittal July 14, 2015

Mine Safety and Health Administration, District 9
Deer Creek Mine 42-00121
Bulkhead Application – Addendum #5
July 14, 2015 Page 1

Addendum #5
Revised Text, Appendices, Figures, Maps and Tables
Response Plan to Address Concerns Outlined
Mine Waste and Geotechnical Engineering Division Letter Dated May 15, 2015

Mill Fork Access #2 Mains, 1st Right Submains Proposed Bulkheads, Rilda Canyon Portal Plugs
– Installation and Monitoring Plan was completely revised to address concerns outlined in the
MSHA Mine Waste and Geotechnical Engineering Division Letter Dated May 15, 2015.
Revisions were made to the following sections:
• Text Section
• Appendices:
o Inclusion of Appendix F
 Keystone Mining Service, LLC, Response to MSHA’s 5/15/2015 Letter
Regarding Bulkhead Portal Plug Construction Plan
o Inclusion of Appendix G
 Bulkhead Strata Immersion Test Results
• Figures:
o Figure 5 (included photos of the installation sites)
• Maps:
o Inclusion of Map 5 – Deer Creek Mine Post Mill Fork Bulkhead Construction
Hydrologic Storage Classification
o Inclusion of Map 6 – Deer Creek Mine Water Storage Volume Outby Mill Fork
Access #2 X-Cut 62
o Inclusion of Map 7- Deer Creek Mine Closure Sequencing
• Tables (re-numbering due to inclusion of tables 2,3 and 8):
o Inclusion of Table 2 – Hydrologic Characteristics of the lower Blackhawk
Formation and Star Point Sandstone
o Inclusion of Table 3 – Rock Strength Data for the lower Blackhawk and Star
Point Sandstone
o Inclusion of Table 8: Mill Fork Area – Groundwater Storage Capacities
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