1997-09-04_REVISION - M1981302

• Permit No: M1981302
• IBM Index Class Name: Revision
• Doc Date: 9/4/1997
• Doc Name: FLATIRONS PROPERTY PROPOSED TR TO PN M-81-032
• From: BEN BINDER
• To: DMG
• Type & Sequence: TR6
• Media Type: D
• Archive: No

• _r _•I• _j1 Ben Binder
• 1045 Lincoln Street, Suite 302 III IIIIIII IIIIII III
StN 0 41997 Denver, Colorado 80203 999
[phone]
j,ii6iU❑JI 5 iaeolog;i September 2, 1997 /
Michael B. Long, Director Di � �
Division of Minerals and Geology
1313 Sherman Street, Room 215 ^l
Denver, CO 80203
RE: Flatirons Property - Proposed "Technical Revision" to Permit M-81-032
Dear Mr. Long: �C.� c1 �� • �'
I understand that on or about September 15'" the Division of Minerals and Geology will approved 1
a"technical revision" to the reclamation plan for the Western Mobile gravel operation that will
authorize additional material to be added to a 6,000-foot earthen levee surrounding the depleted
gravel'pits. The levee under consideration did net exist prior to mining operations. Approval of
this minor"technical revision" will give color to the applicant's claims that the levee is a legally
permitted structure; allow for FEMA certification of the structure; permit flood prone areas of l�
the depleted gravel pits to be officially removed from the 100-year floodplain; and pave the way (`V�
for subsequent development of those flood prone areas.
As you are aware, much of the site is located in the historic streambed of South Boulder Creek 4,3
which drains a steep basin of approximately 125 square miles. The topography of the site has
been further lowered by up to twenty feet by the removal of millions of tons of sand and gravel
from the property. Because of the risk of failure associated with earthen levees, and because
safer alternative solutions have not been studied, both the City and the County governments have
expressed their objections to the "technical revision."
In addition to your agency, I also understand that the Colorado Water Conservation Board also
favors utilizing a 6,000-foot earthen levee to remove flood prone portions of the property from
the floodplain. As an engineer I understand the proclivity for DNR staff to use standard textbook
solutions and design criteria for structures such as levees. But recent meteorological events and
severe flooding in Colorado and throughout the nation have brought into question the wisdom of
relying upon earthen levees to remove areas from natural drainageways. A safer approach is to
utilize reclamation plans that do not create the need for levees and to discourage development in
flood prone areas such as graveled-out creekbeds at the foot of steep major basins.
DMG's actions in this matter will establish a precedent for other gravel pit operators to create
developable parcels by removing flood prone areas from floodplains by building levees created
from fill generated by further excavation of the low-lying areas. Rather than taking actions that
encourage the development of flood prone parcels, Coloradoans would be better served if the
Department of Natural Resources worked to educate the public, and other state agencies such as
the University of Colorado, about the dangers of such development and established policies that
would discourage development in flood prone areas of the state.
I understand the proposed levee is designed for the estimated 500-year flood with flows of
approximately 12,000 cubic feet/second. In fact, the South Boulder Creek basin is capable of
producing floods many times greater than the estimated 500-year flood. A 1996 Emergency
Preparedness Plan prepared by the Denver Water Department for the Gross Dam and Reservoir
located upstream of the subject levee states"the revised Probable Maximum Flood based on
Hydrometeorological Report No. 55A has a peak inflow into Gross Reservoir of
approximately 90,000 cfs." This is many times greater than the 500-year flood in the vicinity of