FS8901-CS 891109 Kimley-Hom and Associates, Inc,
ENGINEERS · PLANNERS · SURVEYORS
12660 Coit Road. Suite 200 Dallas, Texas 75251 214 386-7007 Facsimile 214 239-3820
November 9, 1989
Mr. Russell Doyle, P.E.
City Engineer
City of Coppell
Post Office Box 478
Coppell, Texas 75019
Re: Review of HRWS Tract Floodplain Reclamation Study
Dear Mr. Doyle:
The subject report has been reviewed to determine if it meets the requirements of the City of Coppell
Floodplain Management Ordinance # 87390.
The basis for this potential reclamation is that Nathan Maier has determined that the ineffective flow
area defined by the Corps of Engineers upstream of the St Louis and Southwestern Railroad and
Beltline Road is inaccurate. This determination is due to better a topographic survey provided with
the reclamation study. Based in the topographic map provided, we agree with the redefinition of the
ineffective flow area.
However, we have identified a number of items that we feel need additional clarification. They are
as follows:
1. The Corps of Engineers determination regarding the Section 404 Permit was
made in February of 1988, almost two years ago. In light of the Corps' new
criteria, we recommend an update of the Section 404 determination be
obtained.
2. Since the existing topography of the site is critical to this reclamation study,
we recommend that the City verify that the topography represents conditions
that existed at the time of initiation of the FEMA Flood Insurance Study
(FIS) of the area. The FIS hydraulic model was developed in December 1986.
So, the study was probably initiated in mid 1985. We suggest that the
developer or his engineer certify that the topography of the site has not been
altered after mid 1985.
According to the City ordinance, a number of items are required in order to
approve a reclamation. The following is a list of additional items that should
be provided as required by ordinance.
a. The HEC-2 model should include the 2-year flood profile
according to Article 4C-2. This is needed in order to identify
any potential erosive conditions that might result from the
reclamation. Since this project did not change the flow, just
redefined it, we recommend a waiver of this requirement.
Building client relation shills since 1967
Mr. Russell Doyle, P.E.
-2-
November 9, 1989
The grading plans should include a note that any structures
completed in this area must have the lowest floor elevated
higher than the BFE plus 2 feet, and the 100-year (ultimate)
plus I foot. (Article 4C-2(a))
Flood storage loss data should be provided (Article 4C-2(c)).
This could be easily obtained from existing data.
The topographic survey was certified by a Registered Public
Surveyor. However, it is not dated. This should be done.
Other than the items detailed above, the subject study meets the requirements of Ordinance 87390.
If I can provide additional information, feel free to call me.
Sincerely,
KIMLEY-HORN AND ASSOCIATES, INC.
Senior Hydrologist
pw
11-89/RDoyte. Ctr