ST8601-SY 900905The City With A Beautiful Future
September 5, 1990
Mr. Matthew Miller, P.E.
Risk Studies Division
Federal Insurance Administration
Federal Emergency Management Agency
500 C Street, SW
Washington, D.C. 20472
P.O. Box 478
Coppell, Texas 75019
214-462-0022
Re:
coppell Revised Flood Insurance Study
Case No. 6 - 89 -236
Dear Mr. Miller{
Enclosed please find revised floodway models for a section of Denton Creek
prepared by our consultant, Mr. Ron W. Morrison of Kimley-Horn & Associates, Inc.
In his letter, dated September 5, 1990, Mr. Morrison explains that Dannenbaum
Engineers, Inc. (presently Carter & Burgess Engineers, Ino.) had obtained a
revision of an area in Lewisville adjacent to Coppell along Denton Creek..., etc.
(See attached letter).
Mr. Morrison has completed revised floodway models using a split flow analysis,
which matches the Dannenbaum Channel on one side, while the other side follows
the banks of Denton Creek, leaving an island between the two areas.
We respectfully request that you incorporate this floodway refinement in the
Flood Insurance Study revision that you are presently reviewing for the City of
Coppell.
Please call Ron Morrison or myself, if you have any questions.
Sincerely, ~ ~
'M. "Shobre-- . .
Acting City Enginee~j
MSD/bd ~
/
cc: <Steven G. Goram, Director of Public Work8 John Karlsruher, Ginn, Inc.
Ron W. Morrison, Kimley-Horn & Associates, Inc.
REVFIS.MSD
I' Kimley. Horn I
Kimfoy-Horn and Associates, lac,
ENGINEERS ~, PLANNERS , SURVEYORS
12660Coit Road, Sulle200 Dallas, Texas 75251 214 38'6-7007 Facsimile214 239-3820
September 5, 1990
Mr. Matthew Miller, P.E.'
Risk Studies Division
Federal Insurance Administration
Federal Emergency Management Agency
500 C Street, SW
Washington, D.C. 20472
Coppell Revised Flood Insurance Study
Case No. 6 - 89 -236
Dear Mr. Miller:
This letter is in regard to the ongoing review of the City of Coppell Flood Insurance Study.
During conservations wlth Dannenbaum Engineers Inc. (now Carter and Burgess Engineers,
Inc.) we discovered that there is a particular area of concern along Denton Creek.
Dannenbaum had obtained a revision of an area in Lewlsville adjacent to Coppell along
Denton Creek. Our CoppelI ennlys~s floodplain contained these changes. However,
Dannenbaum's model end revision showed Denton Creek outside of the floodway. This would
allow filling of Denton Creek, which is not keeping with the desires of the City of Coppell.
To correct this matter we have completed a revised floodway model. This model incorporates
a split flow floodway. One side of tile floodway matches the Dannenbaum channel while tile
other side follows the banks of Denton Creek, leaving an island between the two areas. We
have completed a separate floodway model through this area. Since it is not possible to model
a continuous floodway model with this split flow, we have completed four models to represent
tiffs split fIow area. They are:
1. Floodway model downstream of the floodway split. (Attachment I)
Floodway model from Cross Section 223+70 (start of split flow) through the
Dannenbaum (Lewisville side) floodway, ending at Cross Section 255+30 (end of
the split flow). (Attachment 2)
Floodway model from Cross Section 223+70 (start of split flow) through Denton
Creek (Coppell side) ending at Cross Section 255+30 (end of the split flow).
(Attachment 3)
Mr. Matthew Miller, P.E.
- 2 - September 5, 1990
4. Floodway model from the split flow upstream to the end of the floodway model.
(Attachment 4)
We have included the models, floodway delineations, and other details of the hydraulic models
to support this modification to our orlgional submittal. Attachment 5 contains the present
floodway delineation and proposed modification.
A summary of the results of the floodway analysis is included in Table I on the following
page.
On behalf of the City of Coppell we request that you incorporate this floodway reflnement
in the Flood Insurance Study revision you are presently reviewing. Please call if youlhave
questions.
Sincerely,
KIMLEY-HORN AND ASSOCIATES, INC.
Ronald W. Morrison, P.E.
Senior Hydrologist
pw
Attachment
P~PO~D
LEVEE~
,//~FOXi STING -- ;.
O-YEAR-
LOOD ~..~ ,.
PLAIN
PREVZOUS FLOOOWAY MODEL
.11.
PROPOSED SPLIT FLOODWAY