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_. - iii iuiiiiiniiiiii <br />N~~°,~~°14, STATE, OF COLG~v ~~ <br />8r`'$ Roy Romer, Governor <br />/916 <br />DEPARTMENT OF NATURAL RESOURCES ~~ ' <br />MINED LAND RECLAMATION DIVISION ,~+ `~'~ ~ <br />~~,~~~;-~f~~l <br />FRED R. BANTA, Director ,~ i v „ <br />DATE: March 23, 1969 <br />T0: David Berry ~~ <br />/. ~ ~!,~~ <br />FROM: Jim Pendleton ~-!``"'`~ <br />RE: Eckman Parke nel tifications - Areas 7, 31, 41, 51 and 51W <br />(Permit No. - -071) <br />I have the reviewed the packet of information you forwarded to me concerning <br />the riprap installation in reconstructed drainage channels within the above <br />referenced areas at the Eckman Park mine. In the cases of areas 41 and 51 the <br />as-built riprap appears to be somewhat finer in gradation than that specified <br />in the design documents. In these instances I believe it is appropriate to <br />require the operator to demonstrate that the as-built riprap gradation and <br />sizing will meet the design requirements and is, therefore, capable of <br />resisting erosion. <br />The operator has submitted a collection of inspection reports, prepared by <br />ACZ, Inc., a consultant engineering firm. In general, these reports are <br />descriptive of the services conducted at the site and the riprap gradation <br />findings. These reports contain occasional comments suggesting that the <br />as-built riprap sizing, gradation and shape do not correspond exactly with the <br />approved plan's specifications. In addition, these reports often include <br />suggested steps to be followed to resolve a problem and to achieve compliance <br />with the specifications. Except for the final September 230 (23), 1989 <br />inspection report, all deficiencies found were later resolved and noted as <br />resolved to the satisfaction of the inspecting consultant engineer. I suspect <br />that a final report exists which has not been submitted. However, resolution <br />of these final deficiencies should be documented. <br />Testing and laboratory reports were included from Ground Engineering <br />%onsultants, Inc., r+hich addressed the riprap sizing and gradation. In <br />several instances in testing reports dated June 23 through September 12, 1988, <br />the consultant states: "Based on the in-place gradation results, it appears <br />that the material sampled on this date is close to the engineered <br />specifications. However, the specifications don't give a range for the <br />percent passing for each size. We believe that a range should be given for <br />these sizes, as is the case for most gradation specifications". (For example, <br />see Paragraph 3, Page 1, August 31, 1988). In their final report, dated <br />September 7, 1988, a table is included which presents a specified range of <br />gradation sizing for each size of riprap. <br />215 Centennial Building, 1313 Sherman Street Denver, Colorado 80203-2273 Tet. (303) 866-3567 <br />