Copperstone FS-CS 890406 (2)dP
· Jer 'y Parch Consulting Engineers
April 6~ %989
Mr. Russe/1 Doyle,
P.E.
City En~i ne e r
City e~/ Coppeli
CODeefl , Texas 75019
214/'462-0022
RE:
JP No. 88009; Flood Plain Reclamation Study;
West o~ Denton Tap Road; Parks of Coppell;
Coppell, Texas
Dear Russell:
On February 21. 1989 our firm submitted three copies of a rep:orr
entitled Flood Plain Reclamation Study on Cottonwood Branch and
Denton_.Cree~k, Par_ks o_f__CoDp~l~,__Coppet!,__Texas to the City. Th~s
report contained a description of proposed reclamation of ~lood
plain land in the Parks of Coppell on Cottonwood Branch. ~ and~
Denton Creek west of Denton Tap Road. The report lnc~de~
hydraulic models, exhibits, and channel cress sec~ ions as
documentation for our request to the City and to FEI,SA for a
Conditional Letter of Map Revision. We requested that the City
review the study and submit the study to FEMA with an endorsement
of the project.
I have received a letter from FEHA dated March 28, 1989 advis~n~
me that they are currently reviewing our study to determine- th,
appropriate processing procedure. Thank you for expediEin~] ;h~
subnittal of this study to FEHA so that they may begin th--il
On [larch 31, 1989 you provided me with a list of co:.m=nts fro,
Mr. Rot Horrison. P. E. of Kimley-Horn and Associate, s, in,.., who
reviewed our study for compliance with local req~ire:'ents o:
b_half of the City. A copy of Hr. Morrison's letter to you , ~
March 28, 1989 is enclosed. Our responses to H~ . He~r'tson s
comments are presented herein, however, I would first iik~ to
present correspondence which established the basis for our
hydraulic analysis.
All seven comments listed in Mr. Morrison's letter refer to the
current City flood plain ordinance number 87390. In October,
19~8~ upon our submittal of a flood plain reclamation study ~o
permit filling in the flood plain for construction of Parkway
Boulevard extending west of Denton Tap Road and the High School
Access Road, you and I had a discussion and exchanj~d
correspondence regarding the "Grandfathered" status of the flood
plain property in the Parks of Coppell west of Denton Tap Road.
~20 ~Vestway Place, Suite 50] · Arlington, Texas 76018 · Metro [817J 461 2418 · {81/} 4a5 02~,9
Mr. Russell Doyle, P.E.
JP No. 88009
April 6, 1989
Page 3 of 4
With specific regards to Comment No. 2, I agree that the minimum
floor level should be set at base flood elevation <100-year flood
level with existing development conditions) plus two feet. This
will result in an added factor of safety and minimum floor levels
will therefore exceed requirements stated in Ordinance No. ~.
Since projects upstream and downstream of the Parks of Coppell
area have already been developed, however, no further adjustments
in computed flood levels are anticipated.-,
In response to Comment I4o. 6, a letter is attached from the Corps
'of Engineers evidencing approved 404 Permit status of this
project.
in response to Comment No. 7, I will coordinate with you or your
staff to seal copies of the report previously submitted to you.
To the best of my knowledge, FEMA does not require an encine~r's
seal on reports that are a part of Conditional Map Revision
request.
Finally, a general comment on page two in the last paragraph of
Mr. Morrison's letter indicates that our report should address
erosin, flood levels and other impacts for frequencies mentioned
in the March 28, 1989 correspondence. As stated in our report,
these impacts on Denton Creek are insignificant since in
downstream reaches~ encroachments are in non-effective ~]ow
areas. In upstream reaches where the north property line <of th~
Parks of Coppell lies in the creek, no flood plain encroachments
are proposed. Therefore conditions in Denton Creek during
100-year flood and other frequencies ~are similar to current
conditions. Please refer to Table 3 on Page i0 of our report.
On Cottonwood Branch, bank protection is proposed in the vicinity
of the Parkway Boulevard bridge. In other reaches, no
alterations are proposed and velocities are very similar
velocities in the existing channel. This is evidenc~:d
comparision of channel velocities given in the first profil~ ~f
~he existin~ conditions model (See Page 19 - hods= CEX3) and the
firs5 profile of the proposed condition model {See Pa~e 21 Hodei
! trust that the above will satisfactorily address the concerns
listed in Mr. Morriscn's letter. If you concur that the r~su!ts
of our study are in compliance with the requirements of thc City
of Coppelt, please provide a letter to FEMA endorsing our request
for a Conditional Letter of Map Revision for this project.
Russell Doyle,
No. 88009
you have any
err~ parche
please call-
April ~, 1989
page 4 of 4
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KimleY_~orn Letter - 3~28~89 _ 1/18/$9
10114188
Letter from corPS of Engineers
Letter from me to K. Doyle _ 10/7/88
Doyle to me
Letter from K. _ 9/24/$7
Letter from FEMA to me - 6/21/88
Letter from oinn
Letter from m% to ginn - 6~ineer - 5/2b/
Letter from m inn, city m,,~
Letter from ~ to Ginn - 5/3/
from . _ 4/14/~8
Lotto m M. Lame . of C°ppez
Letter fr°[io 219 - CLtY
Ordinance '
_ and AsSociateS -
- ~mleY Horn ~ corporation
Rot [4°rriS°n' pP~m/~Q Developmen~
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Mr · J aY
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