PERMFILE43297

• Permit No: M2004067
• IBM Index Class Name: Permit File
• Doc Date: 9/23/2005
• Doc Name: Blasting Plan Review
• From: Allen Sorenson
• To: Tom Schreiner
• Media Type: D
• Archive: No

STATE OF ~OLOR~DO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman St., Room 215
Denver, Colorado 80203
Phone: [phone]
FAX: [phone]
DATE: September 23, 2005
TO: Tom Schreiner
FROM: Allen Sorenson ~~
RE: Blasting Plan Review of Third Adequacy Review Response, Clear Creek
District Water Providers, LLC, MMRR Quarry, File No. M-2004-067
COLORADO
DIVISION O F
MINESRALS
GEOLOGY
SAFETY•SCIENCE
Bill Owens
Gavemor
Russell George
Executive DlYetlof
Ronald W. Cattany
Division DireROr
Natural Resource Tmstee
The Division of Minerals and Geology (DMG) engineering staff have reviewed the Applicant's blasting
plans as contained in the third adequacy review response dated September 14, 2005. The blasting vibration
control plan provided will be protective of offsite structures, and the DMG can recommend approval of that
plan. It is DMG's understanding that the Applicant is preparing a list of best management practices (BMPs)
for dust control to be submitted for DMG review and approval. The BMPs for dust control during blasting
operations, in addition to those already committed to in September 14, 2005 adequacy response, must
include the following (a diagram with nomenclature is enclosed with this memo):
Blasting with low density explosives such as Ammonium Nitrate and Fuel Oil (ANFO) will be done with
a minimum burden to charge diameter ratio of 25. Blasting with higher density explosives (density
greater than 0.95 grams per cubic centimeter) must use a minimum ratio of 30. If the Operator
determines that lower ratios are desirable, a written proposal with justification must be submitted to
DMG, and written approval from DMG must be obtained prior to employment of the lower ratios in
blasting operations. DMG notes that the blast patterns shown in figure 2 of the Applicant's "Response to
2na Adequacy Review" dated August 19, 2005 are incompliance with the required burden to charge
diameter ratios.
2. For initial blasting operations, the collar distance (stemming) will be equal to burden. Collar distance can
be gradually reduced to a minimum of 70 percent of the burden if careful observations of each blast
indicate that dust generation is not increasing with decreasing stemming. Dust observations must be
recorded in all blasting reports where collar distance is less than burden. If the Operator determines that
collar distances less than 70 percent of burden are desirable, a written proposal with justification must be
submitted to DMG, and written approval from DMG must be obtained prior to employment of the lower
collar distances in blasting operations. Once an acceptable minimum collar distance is approved by
DMG, dust observation recording in blasting reports may be discontinued. As discussed in DMG's
September 9, 2005 engineering memo, and as agreed to in the Applicant's September 14, 2005
"Response to 3ra Adequacy Review" letter, blasting mats or application of thick dirt cover may be used in
lieu of the required minimum stemming. DMG notes that the blast patterns shown in figure 2 of the
Applicant's "Response to 2"a Adequacy Review" dated August 19, 2005 do not specify minimum
stemming requirements.
Office of Office of Colorado
Mined Land Reclamation Active and Inactive Mines Geological Survey