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COLORADO GOLDFIELDS INC. RESPONSE <br />DRMS DEFICIENCY LETTER DATED SEPTEMBER 21, 2011 <br />NOI P- 2011 -027 <br />Deficiency Issue 5: Sedimentation Pond Cleaning Plan <br />The Sedimentation Pond was constructed as part of a 319 Grant from the Colorado Department of <br />Public Health and Environment. The pond dimensions are shown on the attached original construction <br />sketch, and the pond is lined with a 40 mil HDPE liner. <br />For purposes of cleaning the Sedimentation Pond, the portal discharge water has been routed around <br />the pond to permit removal of the sludge in a solid /semi solid state by mechanical means (see Exhibit <br />H). As shown on the attached original construction sketch of the pond, the center section of the pond <br />has a flat bottom with side slopes of 2H:1V and end slopes of 3H:1V. (Note: the Sedimentation Pond <br />was constructed in compliance with this plan.) The plan is to utilize an excavator bucket to remove the <br />sludge from the flat bottom section of the pond. The material on the side slopes and the ends which sits <br />on the slick HDPE liner will slide by gravity to the center flat bottomed section for removal. <br />Approximately 80% to 85% of the solids are expected to be removed by this method. No attempt to <br />completely remove all of the sludge will be made — a small layer will be left on the bottom of the pond <br />as a protection for the liner. The excavator bucket edges will be wrapped with sheet rubber or other <br />suitable material to protect the liner from accidental contact. <br />The existing Sedimentation Pond has approximately 1.5 feet of freeboard, or is essentially full. When <br />the pond is empty, allowing for 1 foot of freeboard, the live volume is approximately 6,400 cubic feet or <br />48,000 gallons. At 50% full, the live capacity is approximately 3,200 cubic feet or 24,000 gallons. At 50% <br />full the residence (settling) time at 20 gpm (estimated average portal flow) is 20 hours. The estimated <br />amount of sediment (primarily limonite) remaining in the bottom of the adit is approximately 3,000 <br />cubic feet. Any additional sedimentation from the planned investigative programs are expected to <br />produce minor amounts of solids (less than 500 cubic feet). <br />In the event that the liner is damaged, one of two solutions will be employed: <br />1. If the damage is small in nature, then the liner will be repaired with a heat fused patch. <br />2. If the damage is significant and patching is impractical, then the existing cavity will be cleaned of all <br />sludge and a new HDPE liner will be installed over the existing liner. The existing liner will serve as <br />bedding for the new liner. <br />