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• Section 780.11(b) Continued. <br />however, recently it began retaining sufficient water to support <br />willows within the impoundment basin. Kerr proposes to partially <br />breach the Pond B embankment and allow the area to continue filling <br />with sediment to create a riparian area. <br />Ponds D and E were created by constructing embankments at the outlet <br />of small existing natural impoundments in order to increase the <br />retention capacity for disturbed area runoff. These ponds contain <br />water year-round. <br />Overburden and Topsoil Structures and Handling <br />No permanent overburden structures were constructed in conjunction <br />with Kerr's mining activities. The overburden stockpile located in <br />the southeast corner of the present Marr Mine area was temporary and <br />was used to backfill the 720 Pit (See Map 33, Overburden Replacement <br />and Grading). The volume of the temporary overburden stockpile was <br />• estimated at 7,100,000 cubic yards. A plan view of the original pile <br />is provided on Map 34a, Kerr Mine Area Peemining Topography. This <br />volume was determined through aerial photogrammetry and related <br />volumetrics and reflects all additions to or removal of material from <br />the stockpile. <br />Dependent on variations in material properties, conditions at the time <br />of recovery and placement, and material handling and placement <br />methods, material swell may vary significantly. Significant changes <br />in material placement methods and material breakdown as a result of <br />multiple handling will have the greatest impact on swell factors. A <br />detailed discussion of material swell factors is presented on page <br />780-4aa. <br />As shown on Map 31, Kerr Mine P.rea Soil Removal and Storage, nine <br />temporary topsoil and subsoil stockpiles were constructed. These new <br />topsoil and subsoil stockpiles have been strategically located and <br />designed to accommodate the design volumes shown on Map 31a, Kerr Mine <br />• P.rea Soil Removal and Storage, with 3:1 slope or less. Stockpiles <br />were maintained and seeded with a rapidly growing cereal grain species <br />.~R-38- 78o-1oa Revised April 2004 <br />M R -3q <br />