CF-Andrew Park 1-PR 990707· ,- Halff Associates
ENGINEERS · ARCHITECTS · SCIENTISTS
PLANNERS · SURVEYORS
June 7, 1999
AVO 1008-99-0187/0188
(214) 346-6200
FAX (214) 739-0095
City of Coppell
732 Deforest Road, PO Box 478
Coppell, Texas 75019
Attn.: Mr. Gary Sims, Director, Leisure Services Department
~"~ ~.,
Re: Proposal for Engineering Services at two sites for the City of Coppc]].
Andrew Brown Jr. Park (East) and Andrew Brown Jr. Park (West). //
Dear Mr. Sims:
Halff Associates, Inc. is pleased to provide this estimate of engineering fees for Permit Application
preparation for two City of Coppell sites, Andrew Brown Jr. Park (East) (ABPE) and Andrew Brown
Jr. Park (West) (ABPW). Improvements at Andrew Brown Jr. Park (East) include the construction of
a pedestrian bridge across Cottonwood Branch, while the Andrew Brown Jr. Park (West)
development involves flood plain reclamation of approximately 5 acres of land in anticipation of the
future construction of 18 tennis courts at the park site.
1. Confluence Hydraulic Study.
It is anticipated that either project will require a hydraulic study of the confluence of Denton
Creek and its tributary Cottonwood Branch. Once performed for one site, this analysi~ will not
need to be repeated for the second site.
The hydraulic study will involve extending the effective Cottonwood Branch hydraulic model
from its current starting conditions upstream of Denton Tap Road to its tree confluence within
Andrew Brown Jr. Park (East). The flow divide between Denton Creek and Cottonwood Branch
will then need to be determined using an iterative procedure. At that point, if the Cottonwood
Branch culvert is undersized, a split flow hydraulic study of the confluence may become
necessary. The hydraulic effort will also involve inserting the recently built Denton Creek
bridge in the effective model.
The analysis will need to be performed using both the fully developed watershed (ultimate
landuse conditions) models and the current effective Flood Insurance Study (FIS) models.
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2. Andrew Brown Jr. Park (East) Site.
In addition to the confluence hydraulic study mentioned above, development of the Andrew
Brown Jr. Park (East) site will include the preparation of a Flood Plain Development Permit to be
submitted to the City of Coppell Engineering Department. Such a permit will require a hydraulic
analysis of Cottonwood Branch based on a fully developed watershed, and a survey of both the
Denton Creek bridge under construction and the existing Cottonwood Branch culverts at Denton
Tap Road.
Other permits for a project of this type generally involve the preparation of a Section 404
(Wetlands) Permit application to the US Corps of Engineers (USACE) and the preparation of a
hydraulic study based on current effective Flood Insurance Study (FIS) hydrology and hydraulics to
be submitted to the Federal Emergency Management Agency (FEMA).
The 1993 Section 404 Permit application for the entire ABPE site shows the Cottonwood Branch
channel as a wetland area. This proposal includes an investigation of the need for a Section 404
Permit based on data available in-house. The actual preparation of a permit application, should it be
required by site conditions, is shown below as optional. Thee fee listed presumes that the site will
qualify for a nationwide permit. Should that not be the case, the fee will need to be adjusted.
Please note that the present proposed permitting effort do__es not include any hydraulic study of the
pe.__d.estrian- bridg~e based on FIS conditions. As you know, the City of Coppell has planned the
preparation of a Final Letter of Map Revision (LOMR) to FEMA for the entire Andrew Brown Jr.
Park (East) site. The analysis of the pedestrian bridge improvements based on FIS conditions can
be addressed at that time. You may want to refer to a November 17, 1998 letter sent to Mr.
Kenneth M. Griffin, P.E., City of Coppell Director of Public Works, that described the overall
permitting needs of the park. A copy of that letter is included with the present letter for your
convenience.
3. Andrew Brown Jr. Park OVest) Site.
The Andrew Brown Jr. Park (West) study will involve the preparation of a Conditional Letter of
Map Revision (CLOMR) to the Federal Emergency Management Agency (FEMA), in addition to
the confluence hydraulic study mentioned above. This submittal will require a hydraulic analysis
of both Denton Creek and Cottonwood Branch, based on current effective Flood Insurance Study
(FIS) models, to determine the impact of the proposed improvements on base flood levels.
A hydraulic analysis based on a fully developed watershed (ultimate landuse conditions) needs also
be performed. However, the preparation of a separate formal report may not be necessary as the
results can be included in the CLOMR report for future reference.
Ill
· ,- Halff Associates
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ENGINEERS · ARCHITECTS - SCIENTISTS
PLANNERS · SURVEYORS
After construction is complete at the Andrew Brown Jr. Park (West) site, FEMA will require the
preparation of a Final Letter of Map Revision (LOMR). The actual construction may not occur for
some time, therefore the LOMR preparation is not included in this fee estimate., ~
The engineering services fee for permitting preparation at the two sites may be broken down as
follows:
1. Confluence Hydraulics (both sites) - $21,250.00
2. Survey of bridge/culvert is included above $ 0.00
3. Flood Plain Development Permit (ABPE only) - $10,750.00 --,--.'~. ~"~'~'~"~'°[~'~al"}' .t..
4. CLO~ Pe~it (~PW only) - 2 creeks $14,000.00 o¢ ~ [~
5. Section 404 (Wetl~ds) Pe~it (~PE only) - optional $ 3,250.00 '
Total: $49,250.00
Permitting for the Andrew Brown Jr. Park (East) site alone would require a budget of $32,000.00 if no
Section 404 (Wetlands) Permit is required, or $35,250.00 if a nationwide permit is required. Similarly,
permitting for the Andrew Brown Jr. Park (West) site alone would require a budget of $35,250.00.
Given the heavy backlog of our survey department, survey of the site may require 1 month lead time
after we receive a signed contract. We anticipate that the Confluence Hydraulic Study may take
approximately 2 months to be completed after surveys are performed. Preparation of the Flood Plain
Development Permit package is contingent on Confluence Hydraulic Study completion and will take
about 4 weeks to accomplish after the final design is agreed upon. The CLOMR Permit preparation is
also contingent on Confluence Hydraulic Study completion and should take about 6 weeks to prepare
after the tennis court layout is finalized. The actual date of both permit submittals will vary with the
number of design iterations that will be required to satisfy the City of Coppell's needs.
Please review this information at your earliest convenience. If it meets your needs, we will be glad to
provide the City of Coppell with a formal proposal and work schedule. Please take the time to call me
at 214-346-6226 if you need additional information regarding this letter. You may also reach Mr.
Walter Skipwith at 214-346-6220.
Sincerely,
HALFF ASSOCIATES, INC.
Sabine Borgnet-Hams, EIT
enclosures
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Mr. Brad Reid, Park Planning and Landscape Manager
Mr. Kenneth M. Griffin, P.E., City of Coppell Assistant City Manager and Director of Public Works