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Cresson Project – AM-11 Adequacy Review <br />Page 13 <br />May 03, 2016 (Revised May 31, 2016) <br /> <br />water produced by the spring enter one of the AGVLF underdrains? If so, <br />which one? <br /> <br />PROJECT DESCRIPTION <br /> <br />4.0 – Physical Background <br />4.5 Geochemistry <br /> Page 4-5: The text states “There will be no significant groundwater flow from <br />underground flow from underground workings to surface water within the permit <br />boundary”. Is there potential for impacted groundwater flow from the proposed <br />underground workings and North Cresson Mine to enter the adjacent <br />drainage(s)? It has been stated in this application that the proposed underground <br />mine and North Cresson Mine will be located inside the diatreme, where the current <br />(bedrock) monitoring well has been dry for many years. Currently, there appears to <br />be no shallow monitoring wells located in Poverty Gulch. Have you considered <br />installing a shallow monitoring well(s) in this drainage area prior to initiating <br />mining activities in this portion of the permit area? Because you have had success <br />in monitoring and sampling from shallow wells in other drainages (e.g., Squaw <br />Gulch, Arequa Gulch, Grassy Valley), the Division believes it may be appropriate to <br />also monitor shallow (alluvial) groundwater in the Poverty Gulch drainage, especially <br />as mining activities increase in this portion of the permit area. <br /> <br /> Page 4-5: The text states “The underground exploration proposed for the Chicago <br />Tunnel may just penetrate the top of the zone of saturation in the northern portion of <br />the diatreme”. However, in Vol II – Hydrogeochemistry Evaluation, Section 3.6.3 – <br />Impact of Underground Exploration and Mining, the text states that the proposed <br />underground mining operation will “be located entirely in the vadose zone above the <br />water table, and will only intersect meteoric water that infiltrates immediately above <br />the mine workings”. Please explain this discrepancy. What is the approximate <br />depth to groundwater in the area of the proposed underground mine? What is <br />the anticipated maximum depth of mining in this area? <br /> <br /> Page 4-5: The text states “Precipitation water infiltrating to groundwater through <br />mine facilities located on the diatreme (mine areas, mine backfill, overburden storage <br />areas, and reclaimed disturbed land) will pass by subsurface flow paths through the <br />diatreme to the regional groundwater table and eventually flow to Fourmile Creek via <br />the Carlton Tunnel portal”. However, the northern portion of ECOSA and a portion <br />of the East Cresson Mine – WHEX are located outside of the diatreme. Additionally, <br />in Volume II, you mention that the underdrains installed under ECOSA have not been <br />functioning properly, and some toe seepage is occurring. Please explain this <br />discrepancy. <br /> <br /> Page 4-5: The text states “The naturally available calcium carbonate in the diatreme <br />along the flowpath for infiltrated water from mined rock prior to and including AM- <br />11 is more than 43 times the mass required to neutralize the products of oxidation of <br />the sulfide minerals exposed by mined rock prior to and including the proposed AM-