Copperstone FS-CS 891011Jerry Parch Consulting Engineers
October 11, 1/
Mr. Ronald ~ Morrison, P.E.
Kimley-Hor~ & Associates, Inc.
12660 Coiy Road
Suite 20~
Dallas, Texas 75251
214/386-7007
RE:
JP 88009; FLOOD PLAIN RECLAMATION STUDY;
Parks of Coppell - West of Denton Tap Road;
Coppell, Texas
Dear Ron:
Enclosed are the following HEC-II models of the 100-year flood in
Cottonwood Branch as adjusted pursuant to our recent discussions.
Reach length in both models is from Section 32816 to Section
8000.
1. MODEL CEXSLAR.DAT - Existing Conditions
2. MODEL CPSLAR.DAT - Proposed Conditions
These models were prepared to comply with FEMA's direction to
begin backwater profiles in Cottonwood Branch with the sl~e-area
method. In accordance with my recent discussions with you an~
with Mr. Jerry Sparks of Dewberry & Davis, FEMA's consultants,
the hydraulic slope used to determine the water surface elevation
at Section 32816 is 0.003 in both models.
Other changes in the enclosed models from the existing and
proposed condition~mede!z we ~ubmi-~tn ynu and to Dewberry &
Davis~__Q~September 2, 1989 are listed below.
COTTONWOOD BRANCH
Changes From 9/2/89 Submittal - Existing Condition Model
1. Sections 24700 - 32725 on Denton Creek are omitted.
2. Right encroachment station at Section 32816 is 1305.
Changes From 9/2/89 Submittal - Proposed Condition Model
1. Sections 24700 - 32725 on Denton Creek are omitted.
Channel width is widened by one foot on the left side
of the channel at Section 32816.
¸3.
Left channel bank station at Section
to 1128.0.
32816 is revised
320 L~/estway Place, Suite 501 · Arlington, Texas 76018 · Metro (817) 467-2418 · (817) 465-0259
Mr. Ron Morrison, P.E.
JP NO. 88009
October 11, 1989
PaGe 2 of 2
Similar to the proposed condition model submitted on September 2,
1989, results shown in the models presented herein indicate that
the proposed bridge and channelization Generate a decrease in the
~e/-en~a~-~h~-~-0~-~year floo~d_~
Please review the enclosed information and, if the revisions in
the existing condition model of Cottonwood Branch listed above
are acceptable, please incorporate these into the revised City of
Coppell Flood Insurance Study and submit the revised model to Mr.
Jerry Sparks of Dewberry & Davis.
By copy of this letter and enclosures, we are submitting models
CEXSLAR.DAT (Existing Conditions) and CPSLAR.DAT (Proposed
Conditions) to Dewberry & Davis and request that
of Cottonwood Branch submitted in oust. 1989 ~pDrt-
models
with these. ~]q_t-~-f ~o--n~i'~f-hg ~-'-sl~-i/arity of the Parks of
Coppell and the Revised Flood Insurance Study
models of Cottonwood Branch, we trust that Dewberry & Davis will
recommend approval of our request for a Conditional Letter of Map
Revisi~.l~~P_ar_k~of Coppell project.
If you have any questions, please call. I appreciate your prompt
consideration and response to this request and the cooperation
you have Given us thus far in resolving this matter. Thank you.
Sincerel¥~,]
Jer~y Parche'
JP:ch
Enclosures:
HEC-II MODEL CEXSLAR.DAT - Existing Conditions in
Cottonwood Branch
HEC-II MODEL CPSLAR.DAT - Proposed Conditions in
Cottonwood Branch
Creek Cross Sections - Cottonwood Branch, as
revised October, 1989 (Sheet No. 6)
cc:
Mr. Jerry Sparks/Dewberry & Davis w/encl.
Mr. Jay Chester, P.E./ABQ Development Corporation
Mr. Russell Doyle, P.E./City of Coppell