Laserfiche WebLink
Ms. Erica Crosby <br />Division of Minerals and Geology <br />April 5, 2006 <br />Page 16 of 21 <br />for any water conveyance or discharge structure to be constructed; and revise the <br />Mine Plan Map to show the location of such conveyance or discharge structure. <br />Please respond. <br />The applicant may discharge either into the Brighton Ditch, or into the South Platte <br />River via a water conveyance easement, pending receipt of all necessary <br />agreements and permits. See response #22 above, as well as the Special Warranty <br />Deed included here as Attachment 7. Per the reserved easement noted in this <br />deed, discharge volume cannot exceed 10 cubic feet per second. Actual discharge <br />volume is likely to be 25% or less of this amount. See potential discharge locations <br />on Exhibit C-3. <br />6.4.7 Exhibit G-Water Information <br />3. The Mine and Reclamation Plan Maps show the locations of five (5) groundwater <br />monitoring wells and the approximate location of the slurry wall surrounding the <br />Phase 2 & 3 Areas. Please clarify the minimum distance of the monitoring wells <br />from the slurry wall. Please respond. <br />Existing monitor wells will be set back at least 25 feet from the outside of the <br />proposed slurry wall location. <br />4. The Division has requested that the Applicant provide baseline water level data <br />already collected. In addition, the Applicant will need to demonstrate how they will <br />provide five (5) quarters of baseline water level data from the monitoring wells prior <br />to exposure of groundwater at the Wattenberg West Pit. If 5 quarters of data has not <br />already been collected, the Applicant may commit to sampling and submittal of such <br />data prior to exposure of groundwater at the site. Further, the Applicant will need to <br />describe how the baseline data callected from the 5 wells will be synthesized to <br />establish baseline groundwater elevation(s) prior to exposure of groundwater at the <br />site. Please respond. <br />The applicant has been collecting monthly baseline data since January 2005 (see <br />Attachment 5), and will continue monthly measurements for baseline purposes until <br />groundwater is disturbed (and monthly thereafter to determine any effect the mining <br />activities may be having on the aquifer for the purposes of determining if and when <br />mitigation measures should be implemented). Just prior to the planned exposure of <br />groundwater, the baseline data will be synthesized as follows and submitted to the <br />Division for review and approval via a Technical Revision: <br />a. For each monitor well, and for each month of the year, the baseline readings <br />from all collected data for that month will be averaged. If all of the readings from <br />that month are within the 2 feet (either higher or lower) of the average, that <br />average plus and minus 2 feet will be used as upper and lower trigger points for <br />that particular well for further study and potential mitigation. Each well will <br />therefore have its own upper and lower trigger points. <br />