1990-01-09_REVISION - M1988112 (6)

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'90 01109 18s42 • $ 303 985 9947 SRK DENVE~ 6ATTLE MOUNTAIN RESOURCES, SAN LUIS PROJECT CMLRD ADEQUACY LETTER RESPONSES Page 22 of 2B Concurrently with flow reduction of process related chemicals the chemical makeup of the solution is anticipated to Change. Reduction in free cyanide levels and a decrease in total dissolved solids is anticipated through natural geochemlcal reactions. Precioitation on the embankment will result in infiltration and subsequent drainage from the embankment. Periodically, following rainfall events and seasonally following snowmelt, an increase in flow from the drain network will occur. This flow will reflect similar water quality to the groundwater of the pro,~ect area. As the drainage rate decreases the potential for leakage from the liner system will also decrease, Both the source of seepage and the hydraulic head applied to the liner will reduce. The long-term potential of seepage is, therefore, less than the coperational conditions discussed in Response 11. Post reclamation infiltration over the surface of the facility is predicted to be minimal, even following mador storm events. Routing of storm water out of the facility will occur within a short period following the storm. The bulk of infiltration is also anticipated to be removed from the upper surface layer of the reclafined area by the evapotranspiration process. No detectable effect of infiltration over the facility's surface following reclamation is predicted. Based upon the extremely low level of potential seepage or flow predicted from the facility following reclamation, no modelling is considered necessary. 40. The final topography on the tailings surface is described as being created by selective deposition at the end of operations such thet only minor grading 1s expected prior to topsoil placement and revegetation. It is noted in Appendix L (Spillway Design Calculations) that the reclamation p)an may spigot clean material and seed, rather than using earth movers to grade the surface." Please clarify the method proposed for topsoil distribution and seeding on the tailings surface. RESPONSE: The method proposed for topsoil distribution and seeding on the tailings surface is, as described on pages E-3 and E-5, initially selective deposition, followed 6y minor grading, and finally topsoil placement and revegetation. The method described in Appendix L is incorrect and has been deleted from the text. 12