Grapevine Creek-CS 951110 Federal Emergency Management Agency
Washington, D.C. 20472
CERTIFIED MAIL IN REPLY REFER TO:
RETURN RECEIPT REQUESTED Case No.: 95-06-371P
The Honorable Tom Morton Community: City of Coppell, Texas
Mayor, City of Coppell Community No.: 480170
P.O. Box 478 Panel Affected: 0010 E
Coppell, Texas 75019 Effective Date of
This Revision: N 0 ~.! ~. 0 ] 9 9 5
102-D-A
Dear Mayor Morton:
This is in response to a request for a revision to the effective Flood Insurance Study (FIS) and National
Flood Insurance Program (NFIP) map for your community. Specifically, this responds to a letter dated
July 3, 1995, from Mr. Mark W. Roberts, P.E., Project Manager, Nathan D. Maier Consulting
Engineers, Inc., regarding the effective FIS report and Flood Insurance Rate Map (FIRM) for the City
of Coppell, Texas. Mr. Roberts requested that the Federal Emergency Management Agency (FEMA)
revise the effective FIRM to show the effects of more detailed topographic information from
approximately 265 feet downstream of Interstate Highway 635 (IH-635) to approximately 240 feet
upstream of IH-635 along Grapevine Creek. In addition, this reque.st incorporates the annexation of a
portion of Dallas County, Texas, along the right-of-way of IH-635 from Cotton Road to Beltline Road.
This request follows up on a Conditional Letter of Map Revision, which was issued on June 28, 1990.
During our review, we discovered that an elevation label for the flood having a 1-percent chance of being
equaled or exceeded in any given year (base flood) approximately 265 feet downstream of IH-635 was
incorrectly shown on the effective FIRM. The base flood elevation (BFE) label shown as 522 on effective
FIRM Panel 0010 E should be 521. This BFE of 521 feet was also shown incorrectly on effective Profile
Panel 05P in the FIS report as 520 feet. The correct BFE of 521 feet was determined in the effective
hydraulic analysis. In addition, Profile Panel 05P was revised from approximately 5,130 feet downstream
to approximately 265 feet downstream of IH-635 to make minor corrections to the Flood Profile and the
channel invert to match the effective hydraulic analysis. All corrections were made as part of this
revision.
All data required to complete our review of this request were submitted with Mr. Roberts' letters dated
July 3, September 12, and October 9, 1995, and a letter dated October 6, 1995, from Mr. Kenneth M.
Griffin, P.E., Assistant City Manager/City Engineer, City of Coppell. All fees necessary to process this
Letter of Map Revision (LOMR), a total of $2,020, have been received.
We have completed our review of the submitted data and the flood data shown on the effective FIRM for
the City of Coppell and Dallas County, and have revised the FIRM for the City of Coppell to modify the
elevations, floodplain boundary delineations, and zone designations of the base flood along Grapevine
Creek from approximately 265 feet downstream of IH-635 to approximately 240 feet upstream of IH-635.
2
The pre-project hydraulic analysis incorporated more detailed topographic information from approximately
265 feet downstream of IH-635 to approximately 240 feet upstream of IH-635. Our review of the pre-
project hydraulic analysis, reveals decreases in BFEs below the effective BFEs from approximately
265 feet downstream of IH-635 to approximately 240 feet upstream of IH-635. The maximum decrease
in BFE, 1.0 foot, occurs approximately 265 feet downstream of IH-635. Our review of the pre-project
hydraulic analysis reveals decreases in the width of the Special Flood Hazard Area (SFHA). The
maximum decrease in SFHA width, 1,670 feet, occurs at IH-635.
The corporate limit boundary has been moved approximately 390 feet east of the boundary on the effective
FIRM because the City of Coppell has annexed a portion of Dallas County. Because the information
submitted affects the City of Irving, Texas, a separate LOMR was issued on the same date as this LOMR
for that community.
The modifications are shown on the enclosed annotated copy of FIRM Panel 0010 E and Profile Panel 05P
for the City of Coppell, Texas. This LOMR hereby revises this panel of the effective FIRM and the
Flood Profile in the FIS report, both dated April 15, 1994.
The following table is a partial listing of existing and modified BFEs:
Existing BFE Modified BFE
Location (feet)* (feet)*
Grapevine Creek:
Approximately 265 feet downstream of IH-635 522 521
Approximately 240 feet upstream of IH-635 524 523**
*Referenced to the National Geodetic Vertical Datum, rounded to the nearest whole foot
**Annexed by the City of Coppell, Texas, from Dallas County, Texas
Public notification of the proposed modified BFEs will be given in the Citizen's Advocate on or about
December 1 and December 8, 1995. A copy of this notification is enclosed. In addition, a notice of
changes will be published in the Federal Register.
Because this LOMR will not be printed and distributed to primary users, such as local insurance agents
and mortgage lenders, your community will serve as a repository for these new data. We encourage you
to disseminate the information reflected by this LOMR throughout the community, so that interested
persons, such as property owners, local insurance agents, and mortgage lenders, may benefit from the
information. We also encourage you to prepare a related article for publication in your community's local
newspaper. This article should describe the assistance that officials of your community will give to
interested persons by providing these data and interpreting the NFIP maps.
The revisions are effective as of the date of this letter; however, within 90 days of the second publication
in the Citizen's Advocate, a citizen may request that FEMA reconsider the determination made by this
LOMR. Any request for reconsideration must be based on scientific or technical data. All interested
parties are on notice that, until the 90-day period elapses, the determination to modify the BFEs presented
in this LOMR may itself be modified.
'Due to present funding constraints, we must limit the number of physical map revisions processed.
Consequently, we will not republish the FIRM and FIS report for your community to reflect the
modifications described in this LOMR at this time. However, when changes to FIRM Panel 0010 E and
the FIS report for your community warrant a physical revision and republication in the future, we will
incorporate the modifications described in this LOMR at that time.
This response to Mr. Roberts' request is based on minimum floodplain management criteria established
under the NFIP. Your community is responsible for approving all floodplain development, including this
request, and for ensuring that necessary permits required by Federal or State law have been received.
With knowledge of local conditions and in the interest of safety, State and community officials may set
higher standards for construction, or may limit development in floodplain areas. If the State of Texas or
your community has adopted more restrictive or comprehensive floodplain management criteria, these
criteria take precedence.
The map panel as listed above and as revised by this letter will be used for all flood insurance policies
and renewals issued for your community.
This determination has been made pursuant to Section 206 of the Flood Disaster Protection Act of 1973
(Public Law 93-234) and is in accordance with the National Flood Insurance Act of 1968, as amended
(Title XIII of the Housing and Urban Development Act of 1968, Public Law 90-448), 42 U.S.C. 4001-
4128, and 44 CFR Part 65. Pursuant to Section 1361 of the National Flood Insurance Act of 1968, as
amended, communities participating in the NFIP are required to adopt and enforce floodplain management
regulations that meet or exceed NFIP criteria. These criteria are the minimum requirements and do not
supersede any State or local requirements of a more stringent nature. This includes adoption of the
effective FIRM and FIS report to which the regulations apply and the modifications described in this
LOMR.
4
If you have any questions regarding floodplain management regulations for your community or the NFIP
in general, please contact the Consultation Coordination Officer (CCO) for your community. Information
on the CCO for your community may be obtained by contacting the Director, Mitigation Division of
FEMA in Denton, Texas, at (817) 898-5127. If you have any technical questions regarding this LOMR,
please contact Mr. Alan Johnson of our staff in Washington, DC, either by telephone at (202) 646-3403
or by facsimile at (202) 646-4596.
Sincerely,
Mitigation Directorate
Enclosures
cc: The Honorable Bobby Joe Raper
Mayor, City of Irving
The Honorable Lee F. Jackson
Dallas County Judge
Mr. Kenneth M. Griffin, P.E.
Assistant City Manager/City Engineer
City of Coppell
Mr. Jack Angel, P.E.
Public Works Director
Department of Public Works
Division of Engineering
City of Irving
Mr. Mark W. Roberts, P.E.'
Project Manager
Nathan D. Maier Consulting Engineers, Inc.
CHANGES ARE MADE IN DETERMINATIONS OF BASE FLOOD ELEVATIONS FOR THE CITIES
OF IRVING AND COPPELL, DALLAS COUNTY, TEXAS, UNDER THE NATIONAL FLOOD
INSURANCE PROGRAM
On September 19, 1980, for the City of Irving, and April 15, 1994, for the City of Coppell,
Dallas County, Texas, the Federal Emergency Management Agency (FEMA) identified Special Flood
Hazard Areas (SFHAs) through issuance of Flood Insurance Rate Maps (FIRMs).
The Mitigation Directorate has determined that modification of the elevations of the flood having
a 1-percent chance of being equaled or exceeded in any given year (base flood) for certain locations in
the Cities of Irving and Coppell is appropriate. The modified base flood elevations (BFEs) revise the
FEMA FIRMs for the communities.
The changes are being made pursuant to Section 206' of the Flood Disaster Protection Act of 1973
(Public Law 93-234) and are in accordance with the National Flood Insurance Act of 1968, as amended
(Title XIII of the Housing and Urban Development Act of 1968, Public Law 90-448), 42 U.S.C. 4001-
4128, and 44 CFR Part 65.
A hydraulic analysis was performed to incorporate more detailed topographic information from
approximately 240 feet upstream of Interstate Highway 635 (IH-635) to approximately 100 feet upstream
of Royal Lane; a berm constructed along the left overbank from approximately 420 feet upstream of
IH-635 to just downstream of Royal Lane; a resurvey of the bridge at Royal Lane along Grapevine Creek
in the City of Irving; more detailed topographic information along Grapevine Creek from approximately
265 feet upstream to approximately 240 feet upstream of IH-635; and a BFE label correction
approximately 265 feet downstream of IH-635 in the City of Coppell. This has resulted in increases and
decreases in SFHA and BFEs from approximately 265 feet downstream of IH-635 to approximately
100 feet upstream of Royal Lane. The table below indicates the modified BFEs for several locations
along the affected length of Grapevine Creek.
2
Existing BFE Modified BFE
Location (feet)* (feet)*
Approximately 265 feet downstream of IH-635 522 521
Approximately 240 feet upstream of IH-635 524 523**
Approximately 1,300 feet upstream of IH435 526 527***
Just downstream of Royal Lane 531 530
Approximately 100 feet upstream of Royal Lane 532 532
*Referenced to the National Geodetic Vertical Datum, rounded to the nearest whole foot
**Corporate Limits of the Cities of Irving and Coppell, Texas
***Annexed by the City of Irving, Texas, from Dallas County, Texas
Under the above-mentioned Acts of 1968 and 1973, the Mitigation Directorate must develop
criteria for floodplain management. For the communities to participate in the National Flood Insurance
Program (NFIP), the communities must use the modified BFEs to administer the floodplain management
measures of the NFIP. These modified BFEs will also be used to calculate the appropriate flood
insurance premium rates for new buildings and their contents and for the second layer of insurance on
existing buildings and contents.
Upon the second publication of notice of these changes in this newspaper, any person has 90 days
in which he or she can request, through the Chief Executive Officers of the communities, that the
Mitigation Directorate reconsider the determination. Any request for reconsideration must be based on
knowledge of changed conditions or new scientific or technical data. All interested parties are on notice
that until the 90-day period elapses, the Mitigation Directorate's determination to modify the BFEs may
itself be changed.
3
Any person having knowledge or wishing to comment on these changes should immediately notify:
The Honorable Bobby Joe Raper
Mayor, City of Irving
P.O. Box 152288
Irving, Texas 75015-2288
or
The Honorable' Tom Morton
Mayor, City of Coppell
P.O. Box 478
Coppell, Texas 75019
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