FLOOD00852

• County: Arapahoe
• Community: Arapahoe County
• Stream Name: Cherry Creek
• Title: Cherry Creek River Run Improvements
• Date: 9/1/1986
• Prepared For: Arapahoe
• Prepared By: Greiner Engineering Sciences, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Federal Emergency Management Agency
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CERTIFIED MAIL
RETURN RECEIPT REQUESTED

JAN

9 1986

Mr. Stephen A. Prokopiak
Greiner Engineering Services, Inc.
570 W. 44th Avenue
Denver, Colorado 80216

Dear Mr. Prokopiak:

This is in response to your letter dated November 4, 1985, requesting that the
Federal Emergency Management Agency (FEM;;') issue a conditional Letter of Map
Revision (LOMR) for proposed improvements alor~ Cherry Creek between Arapahoe
Road and the Arapahoe-Douglas County line, as shown on Panel 0037 of the effective
Flood Insurance Rate Map (FIR\'I) for Arapahoe County, Colorado.

With your November 4 letter, you submitted a report entitled Feasibility Studv
for the Cherrv Creek Basin Drainaaewav, dated July 1985, prepared by BRW, Inc.,
and WRC Engineering, Inc. This report includE'S preliminary design drawings
showing proposed improvements and proposed laO-year flood plain boundaries for
Cherry Creek. Also included in this rep~rt are cross section drawings showing
proposed improvements and proposed lOO-year water-surface elevatior~s.

The conditional LCMR request is based on hydrcllogic and hydraulic information
presented in a report entitled River Run Devel~o"ment Letter of ~ Revision,
Arapahoe Countv, Colorado, prepared by Greiner Engineering Services, Inc. (GES),
dated June 1985. The information presented in the GES report differs from the
information presented in the effective Flood Insurance Study (r'IS) report and
on the FIRl'! and Flood Boundary and Flood.ay Map (FEFM) for Arapahoe County.
Because FEMA is revising the effective Frs re~x~rt, FIRM, and FBFM for Arapahoe
County to incorporate the information in the above-menti.oned Gl~S report, no
LOMR will be issued to revise the curreni:ly effective FIRM, FBFM, and FIS report.
Your request for a conditional WMR is being E,valuated relativEl to the information
presented in the GES report.

So that we may complete our evaluation, .e ask: that you submit the following
information within 30 days of the date oE this, letter:

1.

Backwater computations for the 100-year flood and laO-year floodway
for Cherry Creek. These computations must include the effects of
all hydraulic structures and proposed channel modific:ations and the
resulting flood and floodway eLevations must be tied into those shown
on the flood profiles in the eEfective FIS for :Douglas County, Colorado,
upstream, and the above-"",ntio:1ed GES report do'.nstream of the revised
reach, The new lOa-year flood elevations must :not exceed those shown
in the GES report by rore than 1.0 foot at any cross section (unless
adequate measures have been ta<en to eliminate the flood hazard in
the reach where this situation occur,s).

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