ENFORCE31899

• Permit No: M1978052
• IBM Index Class Name: Enforcement
• Doc Date: 11/21/2001
• Doc Name: HOWE PIT REQUEST FOR ADDITIONAL INFORMATION PN M-78-052
• From: DMG
• To: MOBILE PREMIX CONCRETE INC
• Media Type: D
• Archive: No

STATE OF COLORADO
DIVISION OF MINERALS AND GEOLOGY
Department of Natural Resources
1313 Sherman 51., Room 215
D I v 15 l O N O F
Denver, Colorado 80203
Phone: [phone] MINERAL S
FAx: [phone] &
G E O L O G Y
November 21, 2001 RECLAMATION
MINING•SA FETY
Mr
John Hickman Bill Owens
. Governor
Mobile Premix Concrete, Inc. Greg E. walcner
1590 W. 12i6 Avenue Executive Director
Denver, CO 80204-3410 Michael B. Long
Division Director
RE: Howe Pit -Request for Additional Information, Permit No. M-78-052
Dear Mr. Hickman:
Upon review of your Pre-Hearing Statement and Answer and attached reports submitted to the Division on
October 15, 2001 for two (2) then pending possible violations at the Howe Pit, the Division requests the
following information listed below. As you may know, the Division sent a Reason to Believe letter to
Mobile Premix Concrete, Inc. on September 14, 2001 for a possible violation of C.R.S. 34-32.5-116(4)(I)
and Rule 3.1.5(3) for failure to protect areas outside the affected land from slides and other damage and
C.R.S. 34-32.5-116(4)(h) and Rule 3.1.6(1) for failure to minimize disturbance to the prevailing hydrologic
balance of the affected land and of the surrounding area and to [he quantity or quality of water in surface
and groundwater systems both during and after the mining operation and during reclamation. This matter
was continued from the October 17, 2001 Board Meeting in Canon Ciry to the December 12-13, 2001
Boazd Meeting in Denver. The request for additional information is being made to help the Division
determine whether to pursue the possible violation noted above.
1. Please provide copies of any as-built engineering details, photographs, or other records which verify
how, when, and where an outlet control structure was installed at or neaz the intersection of the relocated
Bull Seep and the Bull Seep Slough.
2. Please provide any evidence showing [he existence of apre-existing drainage ditch in the location of
what is now the relocated Bull Seep.
3. Please provide the details of any hydrologic modeling that has been done to identify the cause of the
May 5, 2001 failure of the flood control levee between the relocated Bull Seep and [he South Platte River,
and near the intersection of the relocated Bull Seep and the Bull Seep Slough. Such details should include
the following: a) a discussion of the model used, how and where the model was developed, and the
applicablili[y of the model to the South Platte River near the Howe Pi[, b) the hydrologic inputs used in the
model, c) available data to verify the fluctuation of river stage at or near the May 5, 2001 levee failure area
for the May 3-5, 2001 storm event, d) [he results of the hydrologic modeling, e) the conclusions that have
been developed based on [he modeling results, and f) a discussion of whether and how the model was
calibrated to fit the conditions of the South Platte River near Henderson for the flows experienced on orjust
prior [o May 5, 2001. In particular, the Division's discussions with consultants [o Mobile Premix have
included discussion of modeling results demonstrating that the northernmost of the two now patched
breaches in the levee would have been overtopped during the May 5, 2001 event prior to any significant