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Oxbow A9iuinW 1 J.C- Terhnira/ Revirian TR-03 <br />Il Wrrt Coa/ Rcfun F'an4ty <br />Technical lldequary Comment/Rerponnr <br />Septemhrr S, 2003 <br />Page 9 <br />Elevation bf the noted features will not change and it is anticipated that actual locations on the <br />embankment wall will be within 10 feet of the locations shown on the design drawings, so hydraulic <br />function would not be affected. A railroad crossing permit has been obtained from the Union Pacific <br />Railroad Company (UPRR) subsequent to submittal and review of crossing design information <br />complying with applicable UPRR crossing requirements and specifications. Copies of the railroad <br />crossing permit application and permit are available on request. <br />Sizing of the outlet pipe for the principal spillway is based on the pond hydraulic calculations <br />presented in Exhibit 2.05-E3. The outlet pipe will pass through a steel casing under the railroad <br />roadbed consistent with UPRR design requirements and dischazge at the natural ground surface on <br />the north side of State Highway 133. The principal spillway dischazge pipe, railroad crossing, and <br />dischazge configuration is illustrated by Drawing 6 of the Sedimentation Pond E Embankment Wall <br />Design (MWH, July 2003) report, included in Exhibit 2.05-E4). <br />18) PJeare add to Drawing Na. 2.05-MSI the maximum allowable sediment level (6017, from the rupposting <br />SEDCAD run and page 5 of the derign report). The Drvirian ruggertr the addition of a lower level at with <br />maintenance will be programmed and accomplirhed <br />Response: Given the configuration of Pond E and the use of a concrete embankment structure, it is <br />anticipated that pond clean-out will occur well before sediment levels teach the design sediment level, <br />however, OMLLC does not feel it is appropriate to establish an azbittary clean-out level. Recognizing <br />that sediment deposition is typically not uniform in most sedimentation structures, the need for <br />sediment clean-out will be determined and this work scheduled based on observation during the <br />required sedimentation pond inspections. <br />19J Plearc add to the Sedimentation Pond E Embankment IY/all Design report an appendix that outliner compliance <br />with the requirement of the State Engineer in accordance with C.R.S 37-87-105. <br />Response: Please refer to previous response to Comment 11. <br />30) Pleare indicate on Drawing 1.05-M7 Sheet S of S the lacation(.rf far stockpile north of the rail rtripping limit, and <br />sock rtarage adjacent to the foundation area (ar denribed on page 2.0547x). <br />Response: Map 2.05-M1 (Sheet 5 of 5) shows the final coal refuse facility configuration, with catch <br />benches at 50-Foot intervals and'the first catch bench at elevation G,100 feet. As described on page <br />2.05-47x, soil materials stripped from each successive refuse placement area (bench area) would either <br />be hauled to the permitted Upper Elk Creek Soil Stockpile, or preferably, would be placed as a berm <br />at the northern soil stripping limit. In all cases the northern soil stripping limit Eor each successive <br />bench would be the catch bench area between the bench area being stripped and prepazed for refuse <br />placement and the next bench in the construction sequence. Stockpiled soil material would be <br />protected from erosion by the designed drainage structures and would be identified by appropriate <br />signs consistent with the requirements of Rule 4.02.7. This approach has the advantages of allowing <br />stockpiled soil materials to be pushed over the completed refuse fill bench and outslope azea as each <br />bench is completed and minimizing the time period that soil materials will be stockpiled. A note has <br />been added to [he map legend indicating that catch bench areas would be used for temporary soil <br />stockpiling between progressive coal refuse placement areas. <br />The soil srripping area would include the refuse placement area and the alignments of the designed <br />perimeter ditches. Rock materials recovered during soil stripping would be placed adjacent to the <br />inner limit of the perimeter ditches, within the soil stripping limits. As the perimeter ditches are cut to <br />the design grade and configuration, the stockpiled rock materials would be used as riprap for these <br />ditches as well as for drain material Eor the designed refuse pile underdrain. A note has been added to <br />