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REV90454
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REV90454
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Entry Properties
Last modified
8/25/2016 3:12:10 AM
Creation date
11/21/2007 11:03:14 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1980244
IBM Index Class Name
Revision
Doc Date
4/29/1996
Doc Name
CRESSON PROJECT PN M-80-244 PROCEDURES & MATERIALS FOR 1996 CONSTRUCTION RESPONSE TO OFFICE OF MLR
From
CRIPPLE CREEK & VICTOR GOLD MINING CO
To
DMG
Type & Sequence
TR20
Media Type
D
Archive
No
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of optimum. The April 1996 re-test data, based on four in-situ nuclear density tests, not only <br />gave densities that met or exceeded the minimum dry density, in the range of 118 to 122 pcf, <br />but also demonstrated moisture contents equal of 9.7 to 13.0 percent, which represents moisture <br />contents that are equal to or ~ of optimum. This appears to CC&V to demonstrate that <br />minimal, if any, change in density has occurred, which also suggests that the effect of freezing <br />and thawing has been minimal in an area of no Drain Cover Fill, after a very dry and relatively <br />cold winter which limited snow pack and therefore limited insulation. The re-test data are <br />provided in Attachment 1, <br />CC&V does wish to confirm that the OMLR's concern about freeze-thaw cycles does not involve <br />the pregnant storage area of the Phase II Valley Leach System. There would be no concern in <br />that azea in view of the fact that the Low Volume Solution Collection System Fill is placed <br />between the Drain Cover Fill and the Soil Liner Fill. <br />2. The Bedding for the Pregnant Solution Collection System Pipelines. <br />The referenced letter clarifies that the OMLR's concern has to do with the position of the <br />perforated pipes relative to the underlaying synthetic liner. It would appear that CC&V was not <br />clear in its text description of the location of these pipes. The position of the pipes does not <br />change from that achieved in 1994-5. The OMLR will remember that the HDPE corrugated and <br />perforated pipes under discussion, which are 15"-diameter pipes with 4"-diameter extensions, <br />have been positioned directly on the liner. They are not positioned on top of a layer of Drain <br />Cover Fill. Drain cover fill is shoveled against the pipes to hold them in place as the Drain <br />Cover Fill is pushed around and over them. The OMLR will also recall CC&V explained that <br />the Drain Cover Fill will be thickened over the 15" solution collection system pipes such that <br />they are covered with two feet of that Fill'. Therefore, these pipes will be positioned and <br />protected exactly as they have been for the 1994 and 1995 construction. There have been <br />absolutely no problems with these pipes and no problems with the underlaying synthetic liner <br />throughout construction. <br />3. Method of Placement of Drain Cover Fill and Pressure Experienced by Liner Durin¢ <br />Placement. <br />The OMLR takes the position that the reduction in the Drain Cover Fill poses an inherent <br />increase in risking compromise of the liner. In summary, the OMLR believes the uphill pushing <br />on slopes greater than 4H:1 V with the CQA inspector and laborers "embodies inadequate control <br />and monitoring methodology." The OMLR continues "The decrease of the drain cover fill <br />layer thickness serves to increase the probability of equipment damage occurring to the <br />' CC&V's submission of March 4, 1996 stated "As was presented in the CC&V correspondence of January 9, 1996, the <br />Drain Cover Fill is to be placed to achieve a minimum o(?4 inches o(lhat materiel over the IS inch diameter solution collection <br />pipes. Because the thickness of Drain Cover Fill over these pipes in Phase 1 construction was the same, ?4 inches, there will <br />be no decrease in the protection a((orded the pipe in Phase II construction. This is explained in Section 6 of Attachment 1." <br />4 <br />
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