FIRM-910314[Kimley-Horjn
Kimley -Horn and Associates, Inc.
ENGINEERS • PLANNERS • SURVEYORS
12660 Coit Road, Suite 200 Dallas, Texas 75251 214 386 -7007 Facsimile 214 239 -3820
March 14, 1991
Ms. Shohre Daneshmand P.E.
Acting City Engineer
City of Coppell
Post Office Box 478
Coppell, Texas 75019
Re: City of Coppell FEMA Flood Study Status Report
Dear Ms. Daneshmand:
The purpose of this letter is to provide a complete update of the status of the FEMA FIS
Revision for Coppell. In the interest of brevity we have listed actions by date with a brief
explanation below:
1984 The Corps of Engineers in completing a study of the City of
Lewisville when they discovered that flood elevations for the Elm
Fork of the Trinity River do not match the downstream flood
elevations shown on the effective FEMA maps. To correct this,
FEMA authorized the Corps to restudy the Elm Fork and modify all
adjacent communities 1or the new backwater conditions.
Oct. 1986 The Corps of Engineers completes a restudy of the Elm Fork of the
Trinity River and its effect on adjacent communities.
Oct. 1988 FEMA finishes reviewing the Corps study and issues preliminary maps
to several communities along the Elm Fork. Coppell is one of these
communities.
Nov. 1988 The City of Coppell asks Kimley -Horn to review this preliminary
map. Kimley -Horn discovers that the flood elevations shown on the
map are significantly different from existing conditions. In some
places there is more than a I foot difference.
Jan. 1989 Kimley -Horn completes a revision of the flood maps for the City, and
these are submitted to FEMA to correct the preliminary flood study.
This K imley -Horn study did not correct the Elm Fork flood elevations
since this would have been a monumental task.
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Ms. Shohre Daneshmand P.E. - 2 - March 14, 1991
Sept. 1989 Having completed the Phase I Master Drainage Plan, Kimley -Horn
presented the information to the City and it was transmitted to FEMA
to be included in the FIS Revision.
May 1990 While FEMA was still in the process of reviewing the latest study
revision submitted in September 1989, the Fort Worth District Corps
of Engineers completed a new study of the Elm Fork of the Trinity
River. This Elm Fork Study was developed by the Corps as part of a
Regional Environmental Impact Study, and represented a more
accurate model of exiting conditions. Since it represented significant
increases in flood levels, Kimley -Horn and the City of Coppell felt it
must be included in the Revised FIS. This model was submitted to
FEMA as additional information.
Sept. 1990 FEMA was concerned about the Corps study and requested additional
information including a statement from the Corps that the hydrology
presented represented the best available data for the area.
Nov. 1990 Additional information was requested by FEMA about the Corps
Trinity study, and a request that water surface profiles be plotted at
a different scale.
Dec. 1990 All of the information requested by FEMA in their September 1990
and November 1990 letters was prepared and sent, including a letter
from the Corps verifying the validity of the Elm Fork Trinity River
data.
-� Feb. 1991 A telephone call from FEMA's consultant to Kimley -Horn requested
a review of the panels which contain the floodplain delineation. Their
concern was that when some of the panels were connected, the
floodplain delineations didn't properly match. This correction is being
completed, and will be sent to FEMA by March 19, 1991.
March 1991 FEMA sent a letter stating that they were going to issue a final letter
for the 1988 Preliminary study. While this is being done, they will
continue to complete the review of the City FIS FeVisiolr.
The process of completing a citywide flood study for the City of Coppell was complicated by
two factors. First, the completion of the Master Drainage Plan and second the com letion of
the Trinity River StudL)v the Corps o ngineers. However, to ignore this more accurate
information would not only violate the City ordinance but would also violate FEMA
requirements under the National Flood Insurance Program. This is the reason for the delays
en
expericea �n_lhisstud>j_- _ _—
A conversation with Mr. Joseph Chapman, Management Engineering and Technical Services
Division of FEMA's consultant (Dewberry and Davis Inc.) has led us to produce the following
schedule that we hope reflects the timing for the Flood Insurance Study.
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Ms. Shohre Daneshmand P.E. - 3 - March 14, 1991
TIME SCHEDULE FOR COPPELL FIS ACTIONS
1991 1992
MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB
I
FEMA issues letter of final determination �+
} FEMA completes preparation of the 1988 FIRM
maps I
* Information requested by Dewberry and Davis is submitted to FEMA
* FEMA completes review of the FIS Revision V
* 90 day appeal period for the FIS Revision ends
* FIS map revisions
printed
This means that FEMA will print the 1988 Preliminary FIRM maps in approximately October
1991, and approximately three to four months later they will print the corrected FIS Revision.
If we can further explain this information please let me know.
Sincerely,
KIMLEY- HORNANDASSOCIATES, INC.
Ronald W. Morrison, P.E.
Senior Hydrologist
rwm
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