Grapevine Creek-CS 920707 ALBERT H. HALFF ASSOCIATES, INC.
ENGINEERS · SCIENTISTS · SURVEYORS ~.- ~,~ ~.
DALLAS · ARLINGTON · CHICAGO · FORT WORTH ! /
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2.: ,~?,:.:,~-' Jul), 7, 1992
AVO 10565SS
Federal Emergency Management Agency
1725 I. Street N.
Washington, D.C. 20472
Atto: Mr. Matt Miller
Re: City of Coppell FIS Update
Dear ~Mr. Miller:
Albert H. Halff Associates, Inc. has been working with the City of Coppell, Catellus
Development Corp. and Michael Baker Jr. CM_BJ), the Technical Evaluation Contractor, for our
area to complete the final Letter of Map Revision (LOMR) for the recently constructed Grapevine
Creek drop structure. The channel improvements downstream of this structure were built over
10 years ago, however a LOMR was not issued because of unstable channel conditions at the
transition back to the natural channel. A drop structure to help control erosive velocities has
been constructed and the required technical data for the final LOMR was submitted to ~MBJ in
October 1991. This data has been reviewed and approved by Michael Baker Jr., Inc.
To complete issuance of this Final LOMR, MBJ is preparing a 1000 scale map showing
the correct channel configuration and the drop structure location. In preparing this map they have
found that the Coppell City Limits on the new (1991 Preliminary) FIS maps does not match the
drop structure location (2.200 feet off) shown on the maps included with the LOMR report. This
sw.,.cture is only approximately 20 feet downsn:eam of the co, orate limits so any shift in this linc
makes it appear that the structure is not within the City of Coppell. Figure 5 and Sheet GP-1,
enclosed, show where this boundary should fall in relation to the drop structure. Based on our
re,dew of this problem, it appears that the boundary shown on the preliminary FIS map dated
December 16, 1991 is drawn approximately 200 feet off. A copy of the 12-91 FIRM is included
with this package. The corrected city limit line is shown in red on this copy. This discrepancy
may also be noted by comparison to the city's street map (copy also attached).
We understand that the City of Coppell recently submitted a formal appeal regarding
additional information for the FIS update. This boundary was not specifically addressed in that
submittal. Halff Associates respectfully requests that this boundary, discrepancy be included in
your review of the data submitted by the City of Coppell on June 4, 1992. Copies of all maps
discussed along with a copy of Ordinance No. 86-358 which annexed this property along IH635
are included with this letter.
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ALBERT H. HALFF ASSOCIATES, INC.
ENGINEERS · SCIENTISTS · SURVEYORS
Federal Emergency Management Agency
July 7, 1992
Page 2
Thank you for your time and consideration of this request. Please feel free to call if you
have any questions or need additional information.
Yours vex truly,
ALBERT H. HALFF ASSOCIATES, INC.
n Hansen, P.E.
/sn
Enclosures
cc: David P. Preusch, P.E., Michael Baker Jr., Inc.
Shohre Daneshmand, P.E., City of Coppell, letter only
Pat Acker, P.E., A.H. Halff Associates, Inc., letter only