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Part B Wilson Storage Pond As -Built <br />As required by Rule 4.05.9 (14), the following report is provided to document construction <br />information upon completion of construction. <br />Design information for the pond is presented in Volume 18, Exhibit 7, Item 23, Part L. <br />The as -built drawing for the Wilson Storage Pond is provided in Figure 7-2613-1 and includes <br />plan view, cross-sections, and spillway details. The emergency spillway consists of a minimum <br />2 -foot deep vegetated channel with a 20 -foot minimum bottom width and side slopes near <br />3.OH: 1 V but are typically flatter due to the clay liner installed on the bottom of the pond and the <br />side slopes of the pond. Please see clay liner discussion below. <br />The as -built condition of the pond is approximately 3 to 4 feet lower than the design. The <br />elevation of the entire pond was dropped during construction due to deeper topsoil encountered <br />during stripping than was anticipated during the design of the Wilson Storage Pond. <br />The Wilson Storage Pond was constructed from April to May of 2017, and was regularly <br />inspected throughout construction by a qualified registered professional engineer. The <br />embankment was constructed with fill material that was free of any unacceptable fill material as <br />outlined in the Exhibit 7, Item 23, Part K. Compaction, optimum moisture, and maximum dry <br />density testing was performed in the field during construction of the embankment and the results <br />of this testing are presented Attachment Exh. 7-2613-1. Final field density tests indicated a 95% <br />standard or greater compaction was achieved. <br />During excavation of the Wilson Storage Pond a sand channel was encountered at the bottom <br />elevation of the pond. The sand channel was found to be continuous for approximately 5 feet <br />below the bottom elevation of the pond. The field engineer determined a clay liner would be <br />necessary to cap the sand channel. A clay borrow was identified within a cut area on the Collom <br />Haul Road (Station 172+00 and 173+50), and proctor testing indicated the majority of the <br />materials available were suitable for a clay liner. Compaction and moisture testing was <br />conducted on the clay liner during construction also and this testing indicates that 95% standard <br />or greater compaction was achieved. Finally, permeability tests were conducted on the clays <br />utilized for the liner and indicate a permeability of 2.13E-08 cm/sec. Please see Appendix 7- <br />2613-2 for the proctor testing, compaction, moisture, and permeability testing results. <br />No surface water modeling was conducted for the Wilson Storage Pond as it is not constructed to <br />handled stormwater runoff, and is only utilized to pump water to and from to support mining <br />operations. <br />The final embankment will be broadcast seeded with the seed mixture outlined in Volume 15, <br />Section 4.05.6 Sedimentation Ponds. <br />Exhibit 7 Item 26 Page Exh. 7-2313-1 Revision Date: 6/13/17 <br />Revision No.: TR -112 <br />