Klohn Crippen Berger

This letter summarizes the seismic design basis, criteria and parameters for the Skunk Camp TSF and highlights key elements of a site-specific seismic hazard analysis.

This technical letter presents two conceptual options for transitioning from conventional slurry deposition for Non-Potentially Acid Generating (NPAG) scavenger tailings (in early years) to filtered tailings (in later years) for the proposed Skunk Camp Site.

This letter is in response to questions posed by BGC Engineering "Assessment of Surface Faulting Investigations at the Skunk Camp TSF Location".

Skunk Camp Tailings Storage Facility (TSF) Final Environmental Impact Statement (FEIS) seepage management plan and supporting assessment for input into the regional groundwater model.

The objective of this plan is to support the site-wide reclamation plan (Tetra Tech 2020) by providing the strategy and design for implementing closure measures for the Skunk Camp TSF.

Summary of the Skunk Camp Tailings Storage Facility hypothetical 'dry' slumping extent analysis.

The objective of this letter is to address WR-23 and describe and quantify (where possible) the embedded and adaptive contingencies incorporated into the Skunk Camp TSF design and to demonstrate the design robustness to the above uncertainties.

This report summarizes the results of the geotechnical and hydrogeological site investigations undertaken in 2018 and 2019 to further the current understanding and/or confirm foundation and seepage conditions for the site.

Summary of tailings storage facility (TSF) alternatives seepage control levels (description, schematics and estimated seepage rates) and general comparison to estimated seepage rates for other existing typical TSFs in the region.

The seepage estimate appendix (Appendix IV from the Alternative 6 - Skunk Camp DEIS design report) has been amended with the results of the additional seepage control levels and is attached to this letter.

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Forest Service Point of Contact

John Scaggs
Tonto National Forest
john.scaggs@usda.gov

Apache Leap Special Management Area
Apache Leap SMA website