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CG July z, zooa Mr. Brad Janes Varra Companies 8120 Gage Street Frederick, CO 80516 Subject: Reply to Comments Durham Pit Greeley, Colorado CGRS Project No. 1-135-9540aa Dear Mr. Janes: The following are responses to comments providetl by Mr. Tom Schreiner of Division of Minerals and Geology regarding the dewatering evaluation provided by CGRS, Inc. Mr. Schreiner's comments are addressed by item. Item 10 -CGRS has generated an analytical simulation that assumes a maximum disturbance and a water table depression over 136 acres as presented in Varra's reclamation plan. This simulation predicts no additional drawdown at the Carbaugh well as mentioned in our initial report. A head distribution plate generated by the model is presented as an Attachment. As described in the report, groundwater and seepage water from the Cache La Poudre River are returned to the river and thus the dewatertng operations augment the river flow. Even if recovered water was rtot returned to the river (which will never Ue the case) the total estimated seepage from the river at the maximum mine tlisturbance (13B acres of dewatered area) is estimated at 10 cubic feet per secontl. This value is well below the annual mean stream flow of the Cache La Poudre River, indicating dewatering operations could not dewater the river. As long as water remains in the river dewatering operations will not affect groundwater levels on the north side of the Cache La Poudre river. Item 11 - Page four of our Dewatering Evaluation Report explains that at the time of the report submittal the depth to water in the Carbaugh well (as report by Mr. Carbaugh) was 17 feet. As the well is 37 feet deep there was a 20-foot water column from which Mr. Carbaugh could draw water. We estimated the drawdown induced from mining operations was on the order of nine feet. This impact has already occurred and addition drawdpwn from future mining operations at this location is not anticipated as predicted by analytical solutions, to the extent as described in item 10 above. Item 20 -The Varra mining operation will have an affect on surtace and groundwater systems. Analytical model results referenced earlier pretlids the maximum distance to any measurable drawdown is between 400 and B00 feet from any dewatered mine face. Our analysis does predict impact to the local aquifer, however, the model does not predict that the local aquifer will be depleted as to prohibit adjacent well use, to the extent as described in item 10 above. As mentioned previously, dewatering operations will augment the Cache La Poudre stream flow during active mining operations. C:\WINDOWS\Temporary Internet Files\CoMeM.IESMJFNGA6aWewaterresponse (1).doc