Parks Coppell FS-CS 890406 Jerry Parch Consulting Engineers
April 6, 1989 "-''~' ~-''--
Mr. Russell Doyle, P.E.
City Engineer ' ' ' ~-" ['~7~[ ;,[~7~
City of Coppell
P O Box 478 ~
Coppell, Texas 75019 '~ ' .~
214/4~-J022 ~
RE: JP No. 88009; Flood Plain Reclamation Study;
West of Denton Tap Road; Parks of Coppell;
Coppell, Texas
Dear Russell: ~~
On February 21. 1989 our firm submitted thr~_,_~[,lcs of a rn~kq~t
entitled Flood Plain Reclamation Study on~.ttonwood Branch an~
Denton Cr~--Pa-~-~--~f Coppell, Coppei!, ~as ~o the City_ Thi~
report contained a description of proposed reclamation of flood
plain land in the Parks of Coppell on Cottonwood Branch and
Denton Creek west of Denton Tap Road. The report included
hydraulic models, exhibits, and channel cross sections as
documentation for our request %o the City and to FEMA for a
Conditional Letter of Map Revision. We requested that the City
review the study and submi~ the study to FEMA with an endorsement
of the project.
I have received a letter frem FEMA dated March 28, 1989 advising
me that they are currently reviewing our study to determine the
appropriate processing procedure. Thank you for expediting the
submittal o~ this study to FEMA so that they may begin their
review.
On March 31, 1989 you provided me with a list of comments from
Mr. Ron Morrison, P. E. of Kimley-Horn and Associates, inc., whc
reviewed our study for compliance with local requirements on
behalf of the City. A copy of Mr. Morrison's letter to you of
March 28, 1989 is encicsed. Our responses to Mr. Morrison's
comments are presented herein, however, I would first like to
present correspondence which established the basis for our
hydraulic analysis.
Ail seven commen~s listed in Mr. Morrison's letter refer to the
current City flood plain ordinance number 87390. In October,
1988, upon our submittal of a flood plain reclamation study to
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 exchanged
correspondence regarding the "Grandfathered" status of the flood
plain property in ~he Parks of Coppell west of Denton Tap Road.
320 L~/estway Place, Suite 501 · Arlington, Texas 76018 · Metro (817) 467-2418 · (817) 465-0259
Mr. Russell Doyle, P.E. April 6, 1989
JP No. 88009 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. 219.
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 No. 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 engineer'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 flow
areas. In upstream reaches where the north property line of the
Parks of Coppeli lies in the creek, no flood plain encroachments
are proposed. Therefore conditions in Denton Creek during the
100-year flood and other frequencies are similar to current
conditions. Please refer £o Table 3 on Page 10 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 to
velocities in the existing channel. This is evidenced by
comparision of channel velocities given in the first profile of
the existing conditions model (See Page 19 - Model CEX3) and the
first profile of the proposed condition model (See Page 21-Modei
CPR4).
i trust that the above will satisfactorily address the concerns
listed in Mr. Morrison's letter. If you concur that the results
of our study are in compliance with the requirements of the City
of Coppell, please provide a letter to FEMA endorsing our request
for a Conditional Letter of Map Revision for this project.
Mr. Russell Doyle, P.E. April 6, 1989
JP No. 88009 Page 4 of 4
If you have any questions, please call.
Sincero~/
~Jer~rParche', P.E.
JP:ch
Enclosures: Kimley-Horn Letter - 3/28/89
Letter from Corps of Engineers - 1/18/89
Letter from me to R. Doyle - 10/14/88
Letter from R. Doyle to me - 10/7/88
Letter from FEMA - 9/24/87
Letter from Ginn to me - 6/21/88
Letter from me to FEMA - 6/17/88
Letter from me to Carl Anderson - 6/17/88
Letter from me to Ginn - 6/8/88
Letter from W. Ginn, City Engineer - 5/25/88
Letter from FEMA to Ginn - 5/3/88
Letter from Unives5 - 4/14/88
Letter from M. Baker, Jr. Inc. - 11/8/82
Ordinance No. 219 - City of Coppell
cc: Mr. Ron Morrison, P.E./Kimley-Horn and Associates - w/encl.
Mr. Jay Chester, P.E./ABQ Development Corporation
~ll~i~lellP'-Ho~'~ a~d ,~,~${}Cia i~es! ~'~C. 12660 Coit Road, Suite 2~011~allas, Texas, (214) 386-7007' '~1
Flale~gh. Charlotte. Nashville. Virginia Beach. Dallas. Phoonix.
VVest Palm Beach. Tampa, OdaDdo. FL Lauderdale, Veto Beach. Ft Myers. SMart
i
March 28, 1989
Mr. Russe~ Doyle
City Engflneer '
Cit~,~ of,~'oppell
732 De Forest
Coppell, Texas 75019
Re: Review of Floodplain Reclamation Study by
Jerry Parche' Consulting Engineer
Dear Mr. Doyle:
We have reviewed the subject study and we offer the following comments: (all references to articles
refer to Coppell City Ordinance Number 87390)
i. Article 4C-2 requires that all models must evaluate discharges for the 2-year, 100-year
existing, 100-year ultimate and low flow conditions. The subject study only considered the
100-year existing conditions.
2. Article 4C-2(a) requires that the lowest floor of any proposed structure in the reclaimed area
be elevated higher than the base flood plus two feet and the 100 year ultimate condition flood
plus one foot. We suggest that this statement be included in the approval report so that there
is no confusion about future development.
3. Article 4C-2(b) requires that the existing and fully developed 100-year floodplain be
delineated. The subject report only delineated the existing 100-year.
4. Article 4C-2(c) requires that flood storage loss data be provided so that the City may evaluate
it~ impact, thi~ has not been provided in the subject report.
5. Article 4C-2(e) requires that Flood levels caused by the development plus any anticipated
future developments must be less than the 100-year ultimate flood level and the 1980 FIS base
flood elevation plus one foot. A table showing this comparison should be provided with the
report.
6. Article 4C-2(g) requires that evidence be submitted showing that appropriate permits have
been obtained or coordinated. Evidence of coordination for a Corps of Engineers Section 404
permit is required before this project can be submitted to FEMA.
7. Article 5B-I-2 requires that any report of this nature should be sealed by a Registered
Professional Engineer. To satisfy this requirement Mr. Parche' should seal the report.
'E:CE V D
Building client relationships since 1967
'1
Mr. Russell Doyle
Page Two
March 28, 1989
In addition to the specific requirements above, the report should address any impacts of the proposed
reclamation such as erosion, flood levels, and other impacts not just for the lO0-year existing
condition, but the other frequencies mentioned above. In preparation of any response, Mr. Parche'
should specifically address any differences between the existing condition model in this report and
the existing conditions model presented.
Let us know if you have any questions or comments.
Sincerely,
KIMLF_,-Y-HORN AND ASSOCIATES, INC.
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