2014-06-26_INSPECTION - C2010089

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June 3, 2014 C- 2010- 089/New Horizon North Mine MPB pond was not discharging and the water level was well below the primary spillway. The emergency spillway and primary spillway are stable and functional. As discussed in the field during the inspection, the side slopes will be repaired and reseeded this Fall. As an additional erosion control measure, straw waddles will be placed at a level approximately half -way down the pond's inner slopes entirely around the pond. Spencer Shumate of the OSM shot two slope measurements using a hand -held inclinometer and obtained inner slope measurements of 51% and 53 %. This could be part of the problem with rills and gullies forming on the inner slopes. Following the inspection the OSM and DRMS researched both design and as -built information for the pond. As stated in the Pond NHN -001 As- Built, Appendix 2.05.3(4) -6 of the permit application package (PAP): "embankment inclination: 3 horizontal to 1 vertical, up and down stream slopes." The As -Built shows a 33% slope for inner and outer slopes of the embankments, but they appear to be much steeper than that. Please verify the inner and outer slopes of the Pond NHN -001 are in compliance with the permit conditions and match the certified As -Built information. A Photograph of Pond NHN -001 is shown in Photograph No 2. Also during this inspection we walked the entire lengths of the NHN -001 East and NHN -001 West Ditches that drain to Pond NHN -001. Significant discrepancies between the as -built documentation and what was observed on the ground are noted. NHN -001 Ditches As -Built is provided in Appendix 2.053(4) -7. Map 2.053(4) -7 shows the as -built route of the ditches. Map 2.05.3(4) -8 shows the standard ditch geometry for the different segment types (earthen, armored, and '' /z culverts). As shown on Map 2.053(4) -7, NHN -001 West is broken into 3 segments and NHN -001 East is broken into 7 segments. Different channel lining material is used for each segment as shown on Table 2.05.3(4) -7 -2 NHN -001 Ditch Capacity Demonstrations (As- Built) of Appendix 2.05.3(4)-7 of the PAP. As part of the riprap used on all armored segments a product called Geoweb Cellular Confinment Systems GW30V is used and staked to the channel bottom. The GW30V specifications are given as having a cell width of 12.6 inches and length of 113 inches. In both cases whether the ditch segment is earthen or armored the ditches are reported in the as -built information as triangular in geometry. The original ditch designs are contained in the ARCADIS Report on Sediment Control in Appendix 2.053(4) -1. The original ditch design paramaters are summarized on Table 4, page 10 of Appendix 2.05.3(4) -1 of the PAP. Based on our field observations, the ditches as constructed do not match the original designs or the as -built documentation. We began at the NHN -001 West Ditch on the west side of Pond NHN -001 and walked south beginning with Segment 1 and ending with Segment 3. According to as -built documentation, Segment 1 and 3 are armored with 3 inch and 6 inch riprap, respectively. Nowhere in these channel segments did we encounter 3 inch riprap or 6 inch riprap. The as -built documentation should replicate existing ground conditions. The Geoweb was in place in all cases where there was armoring. It appears that gravel size material was used throughout in place of riprap material. The upper limit for gravel is 3 inches and in all areas it appeared that the material placed was a course gravel ranging from 1 to 3 inches. See Photograph No 3 for West Ditch Segment 1. From the east side of Pond NHN -001 we continued the inspection and walked from Segment 7 around and up to Segment 1 to the approximate location of the topsoil pile storage area. Likewise, in NHN -001 East Ditches all armored sections contained coarse gravel placed over the Geoweb as opposed to 3 inch or 6 inch riprap material as documented in the as -built information (see Photograph No 4). There was no 6 inch Riprap observed in either the West or East Number of Partial Inspection this Fiscal Year: 8 Number of Complete Inspections this Fiscal Year: 4 Page 3 of 9