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New Horizon Mine, C- 1981 -008 October 20, 2011 <br />SL -12 Review 2 <br />occur in 1994, 1995, and 1996, but not in 1998. Please delete 1998 from the seeding list for <br />Phase 3- Area 2. <br />3. On Map R -1, please delete the Topsoiled and Seeded summaries Phase /Area blocks, and • <br />relocate the blocks so that they are clearly legible and do not conflict with other information on <br />the map. Please delete the 1996 Temp Seeding block from Phase 3 Area 3. On the Staats <br />property, the second block from the east was topsoiled in 1995 and seeded in 1996. Please <br />make these changes. Within the Phase 3 Area 1 area, the line extending NE from the NE corner <br />of Pond 007 is a topsoil boundary, rather than a seeding boundary, and should be brown rather <br />than black. Please revise the color. <br />Ground Water Evaluation <br />WFC provided a surface and groundwater quantity and quality impact analysis in Item 5 page 19 of the <br />SL -12 application. The Division does not believe that WFC's conclusions regarding impacts of replaced <br />spoil on groundwater quality are substantiated. The Division has the following questions. <br />4. Concerning impacts from the conversion of overburden to spoil, WFC states that a small <br />proportion of the overburden may produce acid through the oxidation of pyrite. In Item C) <br />Potential impacts of replaced spoil on groundwater quality beginning on page 20 of the SL -12 <br />application WFC presents the following discussion. Calcite is present throughout the <br />overburden. The calcite will serve to buffer the pH of the water slowing the oxidation of pyrite <br />and secondly it will neutralize the acid that is produced. The Division generally agrees with this <br />analysis. However the demonstration for this is not substantiated. WFC states that Well GW- <br />N40, which is southwest of the Phase 3 reclaimed area, best represents the spoil water. <br />However, WFC states on pages 19 and 20 "...no springs have developed anywhere in this area. <br />Well GW -N40 is located immediately down dip from the release areas, and will show any <br />changes in ground water quality before any spring developed on the surface." Since WFC has <br />reported no groundwater quality changes at GW -N40 it clearly shows that GW -N40 is not a good <br />representation of spoil water quality. Further, GW -N40 is a shallow well with a total depth of <br />thirteen feet with a slotted interval from 3.0 -13.0 feet. The well is located outside of the <br />disturbed area and it monitors the alluvium adjacent to Calamity Draw. Water quality would be <br />expected to be relatively good since it monitors infiltrating meteoric and irrigation water and <br />may be directly influenced by flow in Calamity Draw. No further information is presented to <br />show that water samples from GW -N40 are representative of spoil water quality. No trend <br />analysis regarding water quality or water levels from GW -N40 were provided. Our review of <br />GW -N40 water level data from 2001 onward show that the static water levels have remained <br />fairly constant with an occasional drop in water level. This further verifies that GW -N40 has not <br />been impacted by spoil water and is not representative of spoil water quality as presented by <br />WFC in their spoil water chemistry discussion. WFC is comparing GW -N40 (alluvial ground <br />water) to GW -N44 undisturbed overburden groundwater located to the northwest of the <br />reclaimed areas having a total depth of 60 feet with a slotted interval from 20.0 -60.0 feet. From <br />this water quality comparison shown in Table 5 page 22 WFC concludes that the presence of all <br />salts and TDS is lower in the spoil water and therefore the discussion regarding calcite buffering <br />is shown to be true. This is not a good analogy because the Division does not concur that GW- <br />N40 is representative of spoil water quality. <br />