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Slurry Wall Design Report Loloff Pit 5/24/2016 Page 15 of 16 7 LOW PERMEABILITY BERM AND PERMANENT EMBANKMENT DESIGN In order to construct a slurry wall with a maximum height of 75 ft, a low permeability berm will be required to be constructed above the slurry wall between approximate STA. 0+00 and STA 9+56.5 and STA. 33+65 and STA. 55+74 for a total length of 3165.5 ft. Low permeability berm construction coincides with the locations where the working pad is located below elevation 4634 ft. The low permeability berm will have a maximum height of 12 ft and will be constructed between the top of the slurry wall and elevation 4634 ft. The low permeability core is designed to have a minimum thickness of 10 ft and can be constructed with 1 H:1 V sloping sides. Refer to drawing sheets SH-11 and SH-15 to SH-17. The Davis Farm Fines is suitable material to construct the low permeability berm. An approximate volume of 16,100 cubic yards will be required. Material requirements, placement and compaction details are provided in Specification Section 31 23 00 (Appendix D). To create a low permeability tie-in between the top of the slurry wall and the base of the low permeability berm, a 20-foot-wide, 2 foot deep excavation centered on the proposed slurry wall alignment will be excavated and backfilled with Davis Farm Fines. The slurry wall will then be constructed through this low permeability zone. Refer to drawing sheets SH-11 and SH-15 to SH-17. In the event that the slurry wall settles after construction, this will reduce the likelihood of the development of a preferential flow path between the slurry wall and the low permeability berm. If available, backfilling with claystone is a suitable alternative. An approximate 5,400 CY of material will be required to construct the transition zone. To protect the low permeability berm, limited permanent fill slopes have been designed for the project. The permanent fills have been designed to accommodate a 15-foot-wide flat pad at elevation 4634 ft which can be developed for use as an access road around the property. On- site sand and gravels are suitable for use in the permanent fills. Material requirements, placement, and compaction details are provided in Specification Section 31 23 00 (Appendix D). Design of the final reclamation slopes for the proposed reservoir is beyond the current scope of our services. With the exception described above, cuts and fills associated with work pad construction are considered temporary. 7.1 Quality Control Sampling and Testing Brierley Associates subcontractor Martinez Associates will perform compaction testing on the material used to construct the low permeability berm and permanent embankments according to the methods and frequencies specified in Section 31 23 00. Sampling and testing will be performed by personnel experienced in conducting the type of test required. BRIERLEY ASSOCIATES Creating Space Underground