_INSPECTION - C1981012 (15) - Laserfiche WebLink

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January 2,2013 C-1981-012/New Elk Mine LDS • The sequence of culverts under the road up the west side of the RDA(C40, C-B, C39,C45, C-A)were all clear at the time of the inspection. Between the highway and the Purgatoire River. It appeared that very little work had been carried out in this area since the October inspection.Although the suggestions made in that inspection report for a number of small reclamation projects are still valid,it is necessary to highlight some potential compliance issues: • A small diameter culvert, C70,was approved via TR60 and has been installed downstream of a pair of large (unlabelled)culverts that exist under the highway(see photo 11). Given that this system of culverts is downstream of the emergency spillway to pond 8,which is designed for the 100-year/24-hour event, it seems that C70 may be undersized.The Division will review the design of this culvert in conjunction with the mid-term review. • Culverts C14 and C14A were approved to be removed via TR66. Since the discrepancy between the elevation of these culverts and the outlet elevation of the upstream CDOT culvert under the highway means that they cannot currently function as intended,their removal should be given top priority(see photo 12).Level 1. • Culvert C30 was damaged in the middle and must be replaced,with at least 1' depth of cover(see photo 13).Note also that per table 21,this culvert is specified as having a minimum diameter of 48". Level 1. • The section of concrete culvert in ditch D 14,on the south side of the DWDA, should be removed since it compromises the ditch design(see photo 14).Any breach here would flow directly into the Purgatoire River. Level 1. It appears that the culvert was placed to protect access to a future water line valve;the relocation of the line and/or the valve will be the subject of discussion between the Division and NECC,in conjunction with the mid-term review. • Culvert C26 was approved via TR66 as a 60"diameter culvert. Currently it is undersized and,placed in such a way as to form an impoundment(see photo 15). It should be removed and replaced with a culvert of the appropriate diameter,with its base at the same level as the channel's thalweg. Level 1.NECC may decide that it would be preferable,from a long term maintenance perspective,to remove the culvert entirely and restore an open channel; if so,NECC should inform the Division of such intent in writing and the redesign of the channel outlet can be addressed in conjunction with the mid-term review. • The berm on the east side of containment 3 had been compromised and must be restored.Level 3. • The silt fences at both ends of the topsoil SAE needed to be re-keyed, since water seems to have piped beneath the silt fence.Level 3. South of the Purgatoire River: • The outlet of C9 was partially blocked and should be cleaned out.Level 2. • The hydraulic scheme at the east end of D16 must be redesigned.A power pole had been installed in the middle of the ditch,preventing the flow of water to culvert C 16A. Two excavated holes were acting as sumps and were full of water. The ditch must be restored,taking into account the location and depth of underground cables, as a matter of priority. It is expected that this will be addressed in conjunction with the mid-term review. • The system of culverts,C16A-C,had been identified as a problem in October,but were not inspected at this time. Regardless, short-term maintenance is required and possible redesign for the longer term is Number of Partial Inspection this Fiscal Year: 4 Number of Complete Inspections this Fiscal Year: 2 Page 4 of 10