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techniques will increase permeabilities of the material in comparison to the original overburden. <br />Due to truck dumping from the spoil bench, large rock will settle near the bottom of the pit and <br />provide a permeable channel for groundwater flow. The hydraulic conductivity (K) of the spoil, as <br />measured in well GW -N27, is 40 ft/day, which is far greater than any measurement made in the <br />overburden. K values in the overburden generally range from 3.0 to 5.5 ft/day. The New Horizon <br />#1 site has had continued seasonal irrigation from the North Lateral and its secondary ditch which <br />flows immediately north of the New Horizon #1 reclaimed areas. Water from this irrigation and <br />some added precipitation have moved through the spoil and saturated it until it discharges at the <br />low point of the base of the coal which is at the Spoil Spring and the Pond 001 discharge. Flow <br />from this point fluctuates in response to the use of irrigation. It is believed that the spoil in the New <br />Horizon #2 Mine area will remain relatively dry until irrigation is resumed from the West Lateral <br />Ditch. Once this irrigation is resumed, recharge will rapidly infiltrate into the spoil, move to the <br />southwest according to the basal gradient and develop aspiring at the low point of the lowwall crest, <br />as was experienced at the New Horizon #1 Mine. This point is expected to be N = 602,530, E _ <br />1,112,350 @ elevation 5580' which is located in the northwest corner of the perm it area near <br />Tuttle Draw. This point was calculated in cad using the entire excavated area for the mine <br />compared to the surface topography_ If anv Boring develops here, it would diischar e into T uttl e <br />Draw. The Morgan property_ should not experience anv spoil springs <br />Although a large diameter HDPE pipe will be used to carry the ditch water through the permit area, <br />infiltration will begin when the permanent HDPE pipe will be used in re- establishing irrigation in the <br />reclaimed area. This will occur in 2003 for the area east of 2700 Road and will occur after 2010 for <br />the remainder of the mine area west of 2700 Road. It is estimated that full irrigation of the <br />reclaimed area will take place by year 2013. Although the pipe will be used to carry the ditch flow <br />until the end of its useful life in 30 -50 years, its use is not relevant to the prediction of irrigation <br />recharge since this recharge will occur over 99% of the area even when the permanent pipe is in <br />place. <br />From soil information, knowledge ofthe irrigation practices, discussionswith USGS, andthe rainfall <br />date for the site, the following recharge data has been calculated: 2" from rain and snowmelt, 13" <br />from irrigation and 1" from underburden recharge and overburden recharge at the uphill <br />spoil /overburden contact. Total long -term recharge is therefore 16" per year. These predictions are <br />approximate but suffice in predicting the behavior of the groundwater in the spoil. <br />The total affected area is 418 acres. The volume of the reclaim spoil to be recharged below the <br />5580 spoil spring elevation equals 1512 ac,ft. as determined from D.T.M. modeling of the spoil area <br />and the pit bottom. Spoil porosity of 15% is determined for the overburden. This yields a pore <br />REVISED MAY 2010 2.05.6(3) -23 <br />