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Interoffice Memorandum <br />To: Mike Boulay <br />From: Zach Trujillo <br />Subject: New Horizon North Mine Permit No. C- 2010 -089, Technical Revision No. 5, Cost Estimate & Haul Road <br />Construction & Compaction Review <br />Date: 12/16/2013 <br />Mike — <br />I reviewed New Horizon North Mine's (NHN) revised construction and compaction criteria for roads proposed with <br />Technical Revision 5 (TR -5). In TR -5, NHN proposes that road embankments compaction to be evaluated by Proof Rolling. <br />Additionally, NHN added remedial steps for any particular section of road that fails the Proof Rolling compaction test. <br />After my review of NHN's changes to road construction criteria proposed inTR -2, I have the following comments: <br />On NHN's proposed page 5 in Section 2.05.3(3), they removed the final sentence which states, "The minimum safety <br />factor for all embankments will be 1.25." While the Division has no specific rules for safety factor regarding road <br />embankment slopes less than 1.35h:1v, it brings up the question on why NHN would remove this minimum requirement <br />put in by NHN. Please have NHN provide an explanation for removing the minimum safety factor from their haul road <br />construction criteria. <br />In NHN's proposed changes to the haul road construction description, they removed their requirement of compacting all <br />embankment layers to 90 percent of Standard Proctor density. The Rules do not require 90 percent Standard Proctor <br />density for compaction of embankments but states that embankment layers shall be compacted as necessary to ensure <br />that the embankment is adequate to support the anticipated volume of traffic and weight and speed of vehicles to be <br />used for the duration of the road. Please have NHN provide an explanation for removing the compaction minimum <br />criteria of 90 percent of Standard Proctor density. <br />On page 6 of Section 2.05.3(3), NHN states that the Mine Engineer or designated representative shall prepare and <br />maintain records of all subgrade and embankments Proof Roll tests and of any remedial work undertaken as a result of <br />said Proof Roll tests. To ensure compliance, records of the Proof Roll tests should be reviewed. <br />This concludes my review of New Horizon North Mine's (NHN) revised construction and compaction for roads. If you <br />have any questions, feel free to contact me. <br />Sincerely, <br />Zach Trujillo <br />