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RULE 4 PERFORMANCE STANDARDS <br /> <br />Collom – Rule 4, Page 7 Revision Date: 6/20/22 <br /> Revision No.: MR-242 <br />Topsoil Stockpile/Pond Embankment seed mix described below. The active upstream side of the <br />embankment where water will be impounded will be stabilized, where necessary. Areas in which <br />revegetation is not successful or, where rills and gullies develop, will be repaired and revegetated. <br /> <br />Colowyo will inspect the condition of each sediment pond, sediment trap, or future post-mining stock <br />reservoir on a quarterly basis. All of these types of structures meet the requirements of an impoundment, <br />and the inspection procedures will meet the requirements under Rule 4.05.9 (17). Previously, Colowyo <br />has received a waiver from quarterly inspections for several existing stock reservoirs within the current <br />permit area as described under Section 4.05.9. This waiver changed the inspection frequency to annual. <br />Following construction of any future post-mining stock reservoir in the Collom permit expansion area, <br />Colowyo may request a similar waiver but until that is approved, the quarterly frequency would apply. <br />Results of all impoundment inspections will be submitted quarterly. <br /> <br />Topsoil Stockpile/Pond Embankment Seed Mix* <br />Western wheatgrass @ 4 Lbs PLS/Acre <br />Thickspike wheatgrass** @ 4 Lbs PLS/Acre <br />Yarrow*** @ 0.15 Lbs PLS/Acre <br />*mix may be modified as a result of an updated Reclamation Plan, currently under review. <br />**option to replace Thickspike wheatgrass with Beardless bluebunch wheatgrass or Sheep fescue <br />***option to replace Yarrow with Cicer milkvetch <br /> <br />4.05.7 Discharge Structures <br /> <br />Please see Section 4.05.7 in Volume 1. <br /> <br />The design requirements for sediment ponds for the existing operation can be found in Volumes 2D, 2E, <br />or in Exhibit 7, Item 15, in Volume 13 <br /> <br />Design requirements for all sediment ponds associate with the Collom Pit can be found in Exhibit 7, Item <br />23. <br /> <br />4.05.8 Acid-forming and Toxic-Forming Spoil <br /> <br />Acid forming materials do not exist in significant quantities within the overburden to be removed by the <br />mining operations. A discussion on the overburden at the Colowyo operation has been conducted as set <br />forth in Section 2.04.6. A discussion of the overburden monitoring plan is set forth in Section 2.05. <br />Acid-Base Accounting shows that 19 feet out of 4,212 feet of analyzed over- and inter -burden has a net <br />acid-generating potential, and the average acid-neutralizing potential to acid-generating potential ratio is <br />strongly weighted toward acid-neutralizing in each borehole (Exhibit 6, Item 9). <br /> <br />4.05.9 Post-Mining Impoundments <br /> <br />Please see Section 4.05.9 in Volume 1. <br /> <br />4.05.10 Underground Mine Entry and Access Discharges <br /> <br />Colowyo currently conducts surface coal mining exclusively. <br /> <br />4.05.11 Groundwater Protection <br /> <br />Please see Section 4.05.11 in Volume 1.