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HYDRO20761
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Entry Properties
Last modified
8/24/2016 8:42:00 PM
Creation date
11/20/2007 1:44:45 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981041
IBM Index Class Name
Hydrology
Doc Date
3/10/2000
Doc Name
POWDERHORN COAL CO POND 4 CAMEO NORTH PORTAL CERTIFICATION
Permit Index Doc Type
PROF POND CERTIFICATIONS
Media Type
D
Archive
No
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III IIIIIIIIIIIII III <br />999 <br />POWDERHORN COAL COMPANY <br />POND NO.4 -CAMEO NORTH PORTAL <br />CERTIFICATION <br />On December 18, 1991, Larry M. Reschke, PE, certified Pond No. 4 meets or exceeds the <br />design requirements of plans submitted to and approved by the DMG located in Appendix X, <br />Volume 3; Exhibit 21, Volume 5; and appendix W W, Volume 7 of Powderhorn permit <br />application No. C-81-041. The reconfiguration of the permit in 1986 changed the location of the <br />above referenced design information. The pond sizing calculations are presented in Volume 3, <br />Appendix 13-2. A plan view of the pond is presented in Volume 4, Exhibit 88 and a section <br />view is presented in Volume 4, Exhibit 21. <br />The pond was constructed in 1979. The spillway was revised in November and December <br />1991 to establish separate emergency and primary spillways. <br />On February 11, 2000, during a routine DMG inspection, a sinkhole feature was observed in the <br />bottom of pond 4 immediately adjacent to the inside toe of the pond embankment, directly <br />across from the truck loadout structure. The DMG issued notice of violation (CV-2000-001) for <br />failure to construct or maintain sediment pond to provide adequate capacity to treat run-off and <br />to ensure that embankment remains stable during operational life. The abatement required the <br />excavation and reconstruction of a segment of Pond 4 embankment damaged by piping erosion <br />or otherwise exhibiting evidence of instability and provide construction certification by a <br />qualified registered professional engineer in accordance with Rule 4.05.6(10). <br />On February 28, 2000, a 115-foot long segment of Pond 4 embankment was removed and then <br />reconstructed. The fill was placed and spread from the lowest point of the foundation. <br />Materials were spread in layers approximately 12 inches thick and the lifts were made uniformly <br />over the full width of the embankment. Compaction was achieved by wheel rolling with a 980 <br />front end loader with its bucket full of dirt. Compaction was carried to the edge of the fills so the <br />final slopes are firm. Compaction was tested after the first full lift and again when the fill was <br />about 4-feet high. Attached compaction tests confirm the 980 loader provided compactive <br />effort adequate to achieve a unit dry weight at least 90% of maximum the unit dry weight <br />attained in a laboratory compaction test in accordance with the specifications of ASTM 1557, <br />Method C, (modified proctor). <br />In accordance with Rule 4.05.6(10), ponds are to be inspected during construction under the <br />supervision of, and certified after construction by, a qualified registered professional engineer. <br />This certification is for the reconstruction of the115-foot long segment of Pond 4 embankment. <br />An enclosed sketch shows the location of the reconstructed embankment. The construction of <br />the embankment was supervised by J. E. Stover, P.E. I have a wide variety experience in the <br />design and construction of earth fill embankments. The embankment was re-constructed on <br />February 28, 2000. To the best of my knowledge and belief the embankment was constructed <br />in accordance with the approved plan and meets the applicable performance standards and <br />design criteria with the following exception: The top width of the entire pond embankment <br />does not meet tq¢~at~~~'$p}~irement of Rule 4.05.6(11)(h). <br />ral Engineer <br />3_io_oc~ <br />Date <br />....• 6~ <br />>AIAI. EN~• <br />
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