PERMFILE119801

• Permit No: M2000113
• IBM Index Class Name: Permit File
• Doc Date: 3/5/2001
• Doc Name: MAMM CREEK SAND & GRAVEL PIT HYDROLOGIC ADEQUACY REVIEW COMMENTS FILE NO M-2000-113
• Media Type: D
• Archive: No

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STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Revaurces
I31 3 Sherman SL, Room 215
DIVISION OF
Deriver, Colorado 80203
Phone. qU3) 866-3567 MINERAL S
FA\: [phone] $c
GEOLOGY
Date: March 5, 001 RECLAMATION
`~ MINING•SAFETY
To : Gregg Squire, Allen Sorenson, Carl Mount coy°~~,'
~~ GceR E. Walther
From : Tom Schreiner E.eculive Dueclor
M¢hae18 Long
Division Director
RE :Mamm Creek Sand & Gravel Pit -Hydrologic Adequacy Review Comments
File No. M-2000-113
I have reviewed the February 21, 2001 adequacy responses for the "Mamm Creek" Regualar 112
Application. The following adequacy concerns remain outstanding and will need to be addressed
to the satisfaction of the Division prior to a recommendation of approval.
RULE 6.4.4 EXHIBIT D - Minint= Plan
1. The applicant has specified that a copy of the design specifications for bedding and filter
material to be used for the various barrier configurations as shown on Exhibit CS-2 will be
submitted to DMG for their review and approval prior to construction. The Division is in
agreement with this commitment. The applicant/operator should be appraised that such
information will need to be submitted in the form of a Technical Revision.
2. The applicant has specified that the operator intends on constructing a weir on the discharge
end of the Renewable Resource Area (RRA) during runoff and to keep out low flows during
mining. It is imperative that the applicant clarify how the weir will be constructed, provide the
construction costs, provide a plan view and representative cross sectional design, and discuss the
permitting requirements for such a weir as required by the U.S. Army Corps of Engineers.
3. The applicant has specified that the operator is currently performing a 100-year floodplain
study for the RRA and the areas immediately upstream and downstream from the RRA. In order
to evaluate the potential for offsite impacts due to Hooding during mining and reclamation, the
applicant must provide a detailed assessment of the possible impacts expected during a "worst
case" flooding event along with any necessary mitigation measures to be employed. Such an
assessment will need to be reviewed and approved by the Division prior to any site disturbance.
(The assessment may be submitted as a technical revision to [he permit if not available at the
time of the Division's recommended decision date. In [his scenario, the applicant will need to
commit to submittal of such information as a technical revision for review and approval prior to
site disturbance). The intent of the assessment should be to predict or assess any impacts to the
river channel both within the permit area and the upstream and downstream areas during flooding