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MEMORANDUM <br />To: Berhan Keffelew <br />cc: David Berry <br />Tony Waldron <br />From: David Bird <br />Date: 14 August 2008 <br />Subject: DRAFT COMMENTS - Review of CC&V Amendment 09 <br />Below are my questions and comments on CC&V Amendment #9. Some of these were rolled in from <br />my email correspondence to you of 14 March 08. <br />(1) What is the plan for overburden placement in the year 2016? This information is not shown on <br />Drawing C-5. <br />(2) The Division recommends calculating net-acid generation potential for the waste rock through time, <br />so that not only spatial but temporal variations in the geochemical makeup of the rock and the potential <br />leachate can be predicted and understood throughout the life of the overburden storage areas. <br />(3) Would the haul distance make it cost prohibitive to place additional overburden on the existing <br />Squaw Gulch Overburden Storage Area, extending it to the southwest, rather than disturb new ground <br />by placing it in the proposed location? Based on Drawing C-5, it appears that the haul distance from <br />the Wildhorse Extension mine to the proposed East Cresson OSA is roughly equivalent to the distance <br />to the Squaw Gulch OSA. <br />(4) Page 11-9 states that some slope areas may be plated with coarse rock for runoff protection versus <br />revegetation. What are the criteria for determining when a slope is more amenable for one type of <br />amendment versus the other? <br />(5) The description of the "additional conservative environmental design features" for the ECOSA is a <br />bit confusing. On page 11-10, last paragraph, 6th line, a statement is made that the footprint area of the <br />ECOSA will be left in a roughened condition to encourage infiltration into the Grassy Valley feeder. <br />Later, measures are described to "minimize infiltration through the pile." What hydrologic component <br />is being encouraged to infiltrate to the Grassy Valley feeder and why? Is the roughened condition of <br />the footprint designed to inhibit saturation of the ECOSA while at the same time facilitate infiltration <br />that may originate as percolation through the ECOSA, and runoff from the ECOSA and surrounding <br />area that migrates beneath the ECOSA toward the feeder? It is not explicitly stated in this section, but <br />is the advantage of channeling infiltration to the feeder to facilitate capture by the Carlton Tunnel? <br />(6) Is there a monitoring program proposed to evaluate the success of the cap over the ECOSA in <br />preventing the generation of acid and infiltration through the pile?