2011-09-09_REVISION - M1990057 (3)

Home Browse Search

September 9, 2011 4 Ses r. Michael Cunningham Environmental Protection Specialist Division of Reclamation, Mining and Safety Department of Natural Resources 1313 Sherman Street, Room 215 Denver, CO 80203 Re: Permit M1990 -057, TR #3 Adequacy Review, Question 19 Dear Mr. Cunningham, The Union Milling Company 6200 S. Vivian St. Littleton, CO 80127 +1.303.947.3499 RECENED 'EP092011 _ Division of Reclamation, - 0 Mining & Safety Union Milling Company (UMC) is responding to the Adequacy Review of Technical Revision #3 (TR) Question 19, currently on extension until September 9, 2011. Tim Cazier, P.E., Environmental Protection Specialist, prepared a list of questions on August 12, 2011. Mr. Cazier's August 12, 2011 letter was incorporated into the Adequacy Review of Technical Revision #3 (TR) to UMC. The responses to the August 12, 2011 letter have been prepared by CTL Thompson, reviewed by UMC and are presented below. CDRMS question 1. Page 1, second paragraph: The fourth line states "A clay liner with a specified permeability of 1 x 10 gal /day /ft will be installed on the interiorface and floor." This specification is equivalent to nearly 1 x 1 - 11 cm/s and will likely be very difficult, if not impossible to achieve. Please confirm this is the intended specification and how the applicant intends to achieve it. CTL Thompson Response (September 1, 2011 letter) The clay liner permeability units stated in our letter should have been centimeters /second. The specified permeability is 1 x 10 cm/sec. CDRMS question 2. Page 3, first paragraph: The second to last sentence states " we sampled the stockpile created during the excavation for the tailings pond." Please clarify whether the sample(s) taken from this stockpile were intended to characterize the material intended for the construction of the embankment or the in situ natural soil underlying the embankment. CTL Thompson Response (September 1, 2011 letter) The stockpile was sampled so that we could include particles larger than those which were obtained during drilling. We consider the stockpile samples to be representative of both the native soils and the materials which will be used to construct the embankment.