1997-06-04_REVISION - M1981302 ‎(4)‎

• Permit No: M1981302
• IBM Index Class Name: Revision
• Doc Date: 6/4/1997
• Doc Name: PERIMETER LEVEE DEEPE FARM PIT WESTERN MOBILE INC PN M-81-302
• From: DMG
• To: GREGG SQUIRE
• Type & Sequence: AM2
• Media Type: D
• Archive: No

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IAI t OF COLOMDO
DIVISION OF MINERALS AND GEOLOGY
Depa1313 Sherman
n Natural Resources
131 J Sherman SI . Room 215
Denver,Colorado 80203
Phone:[phone]
FAX:[phone] Pi
DEPARTMENT OF
NATURAL
RESOURCES
Roy Romer
DATE: June 4 , 1997 Governor
James S.Lochhead
TO: Gregg Squire Ewcutive Director
Michael B.Long
FROM• Allen Sorenson Z,;;7 Division Director
RE: Perimeter Levee, Deeps Farm Pit, Western Mobile, Inc. ,
Permit No. M-81-302
On 5/29/97 I conferred with Larry Lang, Chief of the Flood Control
and Floodplain Management Section of the Colorado Water
Conservation Board, regarding the perimeter levee at the Deepe Farm
Pit . I received the following information from Mr. Lang during the
meeting:
1 . The existing channel of South Boulder Creek in the vicinity of
the Deepe Farm Pit is a re-alignment of the natural channel . The
natural stream course is believed to run through the location of
the Deepe Farm Pit and toward the Turnpike cloverleaf .
2 . The overbank flow on the west side of the existing channel
during the one percent annual chance flood is routed around the
Deepe Farm Pit by the perimeter levee . The levee prevents South
Boulder Creek from jumping its re-aligned banks into the natural
channel during large flood events .
3 . At the northern termination of the levee, the inundation from
the one percent annual chance flood expands to the west and north
causing an unknown extent of flooding in developed areas north and
northwest of the pit . The levee tends to direct a greater
percentage of flood flows under the South Boulder Creek bridge at
Highway 36 . If the levee were to fail during a flood, or if the
levee were to be removed, a greate- percentage of flood flows would
enter the developed areas north and northwest of the pit, and an
increased area of flood inundation in the developed areas would
result .
4 . The one percent annual chance flood on South Boulder Creek
results in a peak discharge at Highway 36 of approximately 6 , 100
cfs, of which approximately 3 , 850 cfs is on the overbank. These
peak discharges are considered conservative for the purpose of
delineating the one percent annual chance flood inundation area .