FLOOD07938

• County: Douglas
• Community: Castle Rock
• Stream Name: East Plum Creek
• Basin: South Platte
• Title: LOMR - Affected Panel 080050 0170 C - Case No. 99-08-304P
• Date: 12/3/1999
• Prepared For: Castle Rock
• Prepared By: FEMA
• Floodplain - Doc Type: Historic FEMA Regulatory Floodplain Information

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Federal Emergency Management Agency
Washington, D.C. 204-72

CERTIFIED MAIL
RETURN RECEIPT REQUESTED

IN REPLY REFER TO:
Case No.: 99-08-304P

The Honorable Al Parker
Mayor, Town of Castle Rock
P.O. Box 8000
Castle Rock, CO 80104-8000

Community: Town of Castle Rock, Colorado
Community No.: 080050
Panels Affected: 0170 C and 0188 C
E~ective pate of 0 E C 0 3 1999
thIS RevIsIOn:

102-I-C

Dear Mayor Parker:

This responds to a request that the Federal Emergency Management Agency (FEMA) revise the effective
Flood Insurance Rate Map (FIRM) for your community in accordance with Part 65 of the National Flood
Insurance Program (NFIP) regulations. In a letter dated April 26, 1999, Ms. Vera Stepanek, P.E., Project
Engineer, Rocky Mountain Consultants, Inc., requested that FEMA revise the FIRM to show the effects
of construction along Tributary B to East Plum Creek (Tributary B) of two 6O-inch-diameter
reinforced-concrete pipe culverts (RCPs) under Santa Fe Drive approximately 100 feet upstream of the
Atchison, Topeka and Santa Fe Railway (AT&SFR); a detention pond approximately 300 feet upstream
of the AT 𝔰 a pond inlet drop structure approximately 800 feet upstream of the AT 𝔰 three
64-inch-diameter RCPs under Access Road approximately 1,200 feet upstream of the AT 𝔰 and two
66-inch-diameter RCPs under Red Hawk Drive approximately 2,200 feet upstream of the AT &SFR. This
request also included a detailed hydrologic and hydraulic analysis of the reach of Tributary B from
approximately 100 feet downstream to approximately 2,600 feet upstream of the AT&SFR.

All data required to complete our review of this request were submitted with letters from Ms. Stepanek.

With a letter dated June 21, 1999, Ms. Stepanek provided a corporate limits map that shows that the
portion of the area ofrevision west of the AT&SFR was annexed by the Town of Castle Rock.

We have completed our review of the submitted data and the flood data shown on the effective FIRM. We
have revised the FIRM to modify the floodplain boundary delineations of the flood having a I-percent
chance of being equaled or exceeded in any given year (base flood) along the reach of Tributary B from
approximately 100 feet downstream to just downstream of the AT &SFR and from approximately 50 feet
upstream to approximately 2,600 feet upstream of the AT&SFR. As a result of the modifications, the
width of the Special Flood Hazard Area (SFHA), the area that would be inundated by the base flood, for
the revised reach increased in some areas and decreased in other areas. The increases in SFHA width are
a result of the detailed hydrologic and hydraulic analysis for Tributary B. All increases in SFHA width
are contained on the requester's property. Please note that Tributary B was previously labeled as Omni
Drainageway. The modifications are shown on the enclosed annotated copies of FIRM Panel(s) 0170 C
and 0188 C. This Letter of Map Revision (WMR) hereby revises the above-referenced panel(s) of the
effective FIRM dated September 30, 1987.

Because this revision request also affects the unincorporated areas of Douglas County, a separate LOMR
for that community was issued on the same date as this LOMR.