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RULE 2 PERMITS <br />Based on similarities between overburden suitability analysis results in the Colowyo existing permit area <br />and the Collom permit expansion area, and on previous discussions between CDRMS and Colowyo, <br />suspect levels of Sodium Adsorption Ratio (SAR), Selenium (Se), Boron (B), Saturation percent (Sat), <br />and Molybdenum (Mo) will not need to be addressed in more detail to determine if Special Handling <br />Procedures, that are outside the normal pit operational procedures, will be needed in the Collom area. <br />Historically, beginning around 1983, Colowyo initiated overburden monitoring in both the pit <br />(truck/shovel materials) and on regraded overburden. See CDRMS Permit Exhibit 6, Item 4 as described <br />in the associated January 4, 1983 Colowyo memo to Dan Mathews, CDRMS, for an overview of this <br />initial program. Starting in 1990, Colowyo eliminated the in -pit sampling program. Sufficient data had <br />been collected to indicate that all weathered overburden material (ie within — 50 feet of the ground <br />surface) was suitable for replacement onto the reclaimed surface prior to topsoil replacement. Three <br />revisions were submitted to the Division and approved on January 24, 1984, August 17, 1983, April 24, <br />1990, and PR -02 respectively. The following summarizes the requirements of the current regraded <br />overburden (backfill) sampling program and supersedes all previous commitments. It is based on the <br />following limitations of the earlier program. <br />1. Placing weathered overburden material onto reclamation areas prior to final regarding, and <br />2. Sampling regraded overburden at a density of one composite surface sample per 5 acres of <br />regraded spoil. <br />The regrading of overburden is an event that takes place sporadically during the year. Once backfill areas <br />are regraded, but prior to topsoil replacement, the new locations are identified and sampled. A life -of - <br />mine sampling grid has been established on 500 -foot centers, and each sample location on the grid <br />corresponds to a letter/number combination as established on the sampling map. Using this grid interval, <br />each sample location represents an area of about 5.7 acres in size. A hand shovel is used to take small, <br />representative surface samples of spoil across the sample area. <br />Regraded Overburden Suspect Levels: <br />Parameter <br />Suspect Level <br />H <br />Less than 5 or greater than 9 standard units <br />Electrical Conductivity <br />Greater than 12 millimhos/cm <br />Sodium Absorption Ratio <br />Greater than 15 <br />The laboratory results are kept at the mine site. Results of the sampling program are provided in the <br />appropriate Annual Reclamation Report and are periodically checked during CDRMS quarterly complete <br />inspections. <br />The mining sequence for the planned operation is shown on the Mine Plan Map (Map 23B). Cross <br />sections showing the post mining pit backfill are presented on the Pre -Mining and Post -Mining Cross <br />Sections (Map 20C). The temporary overburden stockpile location is presented on Map 23B. The map <br />depicting spoil grading is presented as Map 29B. <br />The spoil suitability and special handling procedures are described in detail in section 2.05.3(1) of the <br />Collom permit revision. The initial development of the stockpile is anticipated to begin during the year <br />2016 with the excavation of the initial box cuts and continue over the next five years of operation <br />dependent on production rates. Following this period, mine pit advancement will allow for placement of <br />mined spoil into the original box cut area. <br />Collom — Rule 2, Page 81 Revision Date: 12/30/16 <br />Revision No.: TR -108 <br />