1997-09-15_REVISION - M1981302

• Permit No: M1981302
• IBM Index Class Name: Revision
• Doc Date: 9/15/1997
• Doc Name: RATIONALE FOR APPROVAL OF TR TR-06 WESTERN MOBILE BOULDER INC DEEPE FARM PIT PN M-81-302
• Type & Sequence: TR6
• Media Type: D
• Archive: No

Rationale for TR-06 Approval-Western Mobile Page 3
Deepe Farm Pit, Permit No. M-81-302
September 15, 1997
for the Extraction of Construction Materials (Act) and the Construction Materials Rules and
Regulations of the Mined Land Reclamation Board (Rules):
1. The map provided with the TR-06 application depicted a reclaimed pit configuration
that was the subject of the then pending amendment AM-02 application. The
Division was concerned that the amendment AM-02 issues and the technical revision
TR-06 issues be separated and required that a new map be submitted. This adequacy
concern subsequently became a moot point when amendment AM-002 was approved
on June 26, 1997. The Division was also concerned that the map provided with the
TR-06 application did not legibly depict those portions of the levee that would be
raised or otherwise modified from the preexisting levee configuration.
2. The location of the Deepe Farm Pit perimeter levee in the one percent annual chance
flood plain of South Boulder Creek gives rise to the potential for adverse off-site
impacts to be caused by the presence of the levee during a flood event. The Act, at
Section 34-32.5-116(4)(b)C.R.S. states that "If earth dams are constructed to impound
water, the formation of such impoundments will not damage adjoining property...,"
and at Section 34-32.5-116(4)(h) C.R.S. that "Disturbances to the prevailing
hydrologic balance of the affected land and of the surrounding area and to the quality
and quantity of water in surface and groundwater systems, both during and after the
mining operation and during reclamation, shall be minimized." Although it is not
clear whether either statutory provision requires a flood hazard analysis, the
Division, as a policy matter in this particular instance, decided to analyze the
potential for flood plain hazard from the levee modification. Therefore, with the
above-referenced statutory citations as a basis, the Division required the operator to
provide analysis of the South Boulder Creek flood plain and the effects on the flood
plain that may be caused by the Deepe Farm Pit perimeter levee.
3. The Division required the operator to provide a demonstration that the levee would
hold during the one percent annual chance flood on South Boulder Creek. This
demonstration was to include design details sufficient to allow evaluation of
freeboard, stability against erosion, seepage through or under the levee, settlement,
cracking, and interior drainage. The operator was also required to address procedures
for long term maintenance of the levee.
Operator's Responses
1. On August 11, 1997, the operator submitted maps of the Deepe Farm Pit that depict
and highlight the contour of the pit perimeter levee as it is proposed to be raised and
modified through the TR-06 proposal. The Division has determined that these maps