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Response to DRMS Comments <br />Varra Coulson Mine Operations <br />Greeley, Colorado <br />Page 3 <br />the reclaimed Coulson mine. A particle tracking simulation was included to show the <br />groundwater flow lines without external influences. This simulation is presented on Plate A in <br />Attachment C. A second simulation shows the influence of the Coulson barrier wall, presented <br />on Plate B. As can be observed the barrier wall diverts groundwater around the mine with only <br />minor variations in gradient. It should be noted that influences associated with the Durham <br />mine pumping, and recharge from the Greeley # 3 Ditch will totally mask any water table <br />variations created by the barrier wall. There is no information that an offsite groundwater <br />user will be adversely affected to any recommended trigger point. <br />21. As a condition of its well permit Varra must provide notification letters to well owners within <br />600 feet of the mine. These notifications will be provided to DRMS. <br />28. The Hanes Property Preliminary Analysis report, which includes the requested boring logs, is <br />provided as Attachment D. Also included is a cross section, which includes the lithology used <br />for the slope failure analysis. We also have included a slope failure model documenting a <br />flooded mine condition at the mine slope of 1.25H:1V. The safety factor increases from 1.27 <br />under dry mine conditions to just less than 1.4 under flooded conditions. As slope failure <br />modeling for a 3:1 slope would result in very high safety factors we do not see the value in <br />reconstructing the model for these conditions. <br />If you have any questions regarding this letter or attachments, please contact me at 970 - 590 -3807. <br />Sincerely, <br />AWES, LLC <br />Joby L. Adams, P.G. <br />Principal /Hydrogeologist <br />cc: Brad Janes — Varra Companies, Inc. <br />AwEs two Fcur Star Court, Fort Collins, CO 8CS24 — 91t - SnC -38(il <br />