2013-07-26_REVISION - M2008078 (4)

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M- 2008 -078 — GP Aggregates, LLC — West Farm Pit — Technical Revision Request No. 2 July 26, 2013 -3- It is anticipated that the interior slurry wall will be removed prior to final reclamation of the site so that a single open pit will remain at the conclusion of mining in the north mining area. Attached is a revised Exhibit C - Pre - Mining /Mining Plan map that shows the revisions discussed above. Exhibit F=— Reclamation Plan Maa Revision to reclamation slope /liner to utilize an impermeable slurry wall to line the finished reservoir in lieu of a compacted clay liner. The reclamation slope has been revised to use an impermeable slurry wall in lieu of a compacted clay liner to achieve a cutoff of groundwater between the surrounding alluvial aquifer and the reclaimed reservoir. The 3:1 reclamation slope will be identical to the mining slope with a minimum setback of 25 feet from the edge of the slurry wall. Attached is a revised Exhibit F - Reclamation Plan map that shows the revised reclamation slope. Reclamation Bond: Revision to the financial warranty required for the reclamation of each phase of mining. 1. The financial warranty calculations have been revised as follows: a. The area disturbed by the construction of the interior slurry wall has been added to the financial warranty required for Phase 1A. b. The financial warranty required for each phase has been updated to reflect the revised locations of the phases and slurry wall costs in lieu of compacted clay liner costs. A revised Exhibit L — Reclamation Costs and supporting calculations are attached which summarize the revision to the financial warranty requirements. GP appreciates your consideration of this revision request and looks forward to your response. Please feel free to contact me with any questions or comments. Sincerely, Todd Yee r UT Consulting,, Inc. Attachments: Revised Exhibit C - Pre - Mining /Mining Plan Map Revised Exhibit F - Reclamation Plan Map Revised Exhibit L - Reclamation Costs and Reclamation Costs Summary Table Revised Financial Warranty Requirement Calculations "Subsurface and Laboratory Data - West Farm Slurry Wall" by J.A. Cesare and Associates dated August 10, 2011 V1 305 Denver Avenue, Suite D • Fort Lupton, CO 80621 • Ph: 303 - 857 -6222 • Fax: 303 - 857 -6224