2012-08-16_REVISION - M1977493 (2)

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The soil berms used to segregate noncontact from contact runoff will be constructed sequentially, particularly in the north side of McNulty Gulch, in advance of OSF construction. This is illustrated by Drawings 13 and 14 that show the diversion berm (green arrows) at the end of year 5 and the end of year 10. In practice new berms will be constructed along the toe of the OSFs and will be buried by the advancing OSF. New berms will be constructed before the older berm is covered by the OSF. Prior to expansion of the McNulty OSF, non - contact water underdrains and a contact water collection system (CWCS) will be constructed (Drawing 10). These drains will ultimately be covered by the OSFs. The staged development locations of the noncontact underdrains and CWCS are shown on Drawings 13, 14 and 15 and are represented by the blue and brown lines, respectively. The noncontact underdrains (blue lines) will collect and convey flows to the East Interceptor System. In the event that it is ever needed, the noncontact drains also can be routed to the SDP. The construction of the contact and noncontact drains is being planned to occur concurrent with reclamation soil salvaging operations so that any new springs encountered during soil stripping can be integrated into the water management system. Once the soil salvage and drain system construction is completed (estimated to be completed in 1 to 2 years), an appropriate protective drain fill cover and waste rock buffer will be placed over areas of the drain system before waste rock placement occurs to prevent potential damage during OSF placement operations. Climax will begin OSF expansion activities sequentially in areas after the soil salvage, drain construction and placement of protective rock cover have been completed. The existing OSF features have been investigated to ensure they provide a proper foundation for the operational and final configurations. The 2011 field investigation included 4 borings and 4 test pits completed through or in the existing overburden stockpiles. These borings and test pits were used to classify overburden materials, and to obtain samples for laboratory testing. Two samples of overburden were subjected to large -scale direct shear strength testing. The results of these tests were used for input when developing representative strengths for use in the geotechnical stability modeling. The geotechnical stability analysis evaluated the stability along 5 different cross - sections. Existing overburden fills exist along all 5 cross - sections. This material was included in the stability model. The results, which account for the presence of existing overburden fills, indicate that the proposed OSFs are stable when placed over existing overburden fills. Sequencing of under -drain construction and overburden placement DRMS would like Climax to provide, to the maximum extent possible, a more detailed description of the proposed sequencing of surface preparation, under -drain construction /certification, and waste rock placement for the North40 and McNulty OSF areas. Response: The sequencing of surface diversion berms and noncontact and contact drain systems is described in the previous response. The surface berms (green arrows in TR -22 Drawings 13 and 14) will be concurrently expanded with OSF material placement so that the water is continually segregated and tied -in with the current noncontact/contact surface drainage systems. During soil salvaging operations, these diversion berms also will remain in place along the toe of the OSFs to ensure segregation is maintained. Climax plans to salvage soil and construct the noncontact underdrains and CWCS drains (both of which will eventually be covered by the 2