St Andrews Est-CS040607 (2)~ TRANSMITTAL [] TELEPHONE ~ MEETING
JOB NA_ME:,S~. Andrews Estates 732 Deforest
DATE: ~-f-04 JOB NO. 324
HE SSEY ENGI ERING, INC.
1417 W. Main, Suite 100
Carrollton, Texas 75006 ~-
(972) 245-9478 Fax: (972) 245-7087 P6~.~WF
~ OBSERVATION
Rd., City of Coppell
FROM: Pete Hennessey P.E.. Dave Evans P.E.
TO:
Karl
PBS&J
12101
Kerr, Floodplain Scientist
Indian Creek Court. Beltsville. MD 20705
Ph. 800 697 7275 Ext 478, 301 210 5157 fax
- Please issue a, "Letter of Map Revision", to
4uestion which should not been shown as floodway.
This should be sent to Keith Marvin, P.E. at
correct the area in
the City of Coppell.
Keith is awaiting this letter for the approval of construction on St.
Andews Estates.
Thank You.
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Federal Emergency Management Agency
Washington, D.C. 20472 February 26, 2004
John D Evans, P.E.
Evans Engineering
1417 West Main Sn'eet, Suite 100B
Carrollton, TX 75006
IN REPLY REFER TO:
CASE NO: 04-06-897A
CO~: CITY OF COPPELL, DALLAS COUNTY, 'IEXAS
COIvIMUNITY NO: 480170
216-AD
RE: 732 DEFOREST ROAD
Dear Mr. Evans:
This is in response to your request for a Letter of Map Amendment for the property referenced above.
The Fedarai Emergency Management Agency (FEMA) uses detailed application/certification forms for
revision requests or amendments to the National Flood Insurance Program (NFIP) maps. The forms
provide step-by-step instructions for requestors to follow, and are comprehensive, ensuring that the
requestors' submissions are complete and mom logically sU'uctured. Therefore, we can complete our review
more quickly and at lower cost to the NFIP. While completing the forms may seem bun:tensome, the
advantages to requestors outweigh any inconvenience.
The following forms or supporting data, which were omitted from your previous submittal,
must be provided:
Please complete the Community Acknowledgement Form (copy enclosed). Additional
information regarding this form can be found on our web site at
http:llwww.fema.govl~tltsd/DL_MT-l.htm or by calling the FEMA Map Assistance
Center toll free at (877) 336-2627 (877-FEMA MAP).
Please note that if all of the required items are not submitt.ed within 90 days of the date of this letter, any
subsequent request will be treated as an original submittal and will be subject to all submittal procedures.
When you write to us concerning your request, please include the case number referenced above in your
letter. All required items and questions concerning your request ~e to be directed to the following address:
FEMA LOMA Depot
PBS&J
12101 Indian Creek Court
Beltsville, Maryland 20705
I(y~u I~.~,~- ~3'-C]~'~'~-o~- ~:-t~'~ng FEMA policy, o~--~-~-~fi-~enem]~ pi~ase e0n~t ~ I~MA Map
Assistance Center toll free at (877) 336-2627 (877-FEMA MAP) or by letter addressed to the Federal
Emergency Management Agency, 12101 Indian Creek Court, Beltsville, MD 20705. Additional
information about the NFIP is available on our web site at http://www.fema, gov/nfip/.
Sincerely,
Doug Bellomo, P.E., CFM, Acting Chief
I-T~'~ideniification Section
Emergency Preparedness and Response Directorate
06/03/04 TIIU 15:27 FAX 9722393820
and Associates, Inc,
DALLAS
[~002
June 3, 2004
Mr. Kenneth M. Griffin, P.E.
Director of Engineering and Public Works
City of Coppell
255 Parkway Boulevard
Coppell, TX 75019
Re:
Review of CLOMR Request on Old Denton Creek
St. Andrews Estates
City of Coppell, Texas
KItA No. 063124006
De~ Ken:
We have completed our review of the referenced Conditional Letter of Map
Revision (CLOMR) request for the proposed subdivision. The following
comments are based on the requirements outlined in the City of Coppell Drainage
Manual and Federal Emergency Management Agency (FEMA) criteria.
Comments are in no particular order and should be addressed by number, lC, JlA
recommends that:
This report appears to be a combination of two submittals to FEMA. The
first submittal is a Letter of Map Revision (LOMR), the purpose of which
would be to correct a mapping error on the effective FIRM. The second
submittal is a Conditional Letter of Map Revision based on Fill (CLOIVlR-
F). The CLOMR-F submittal would be based on the proposed filling of the
finger of the floodplain that extends into the subject tract. These submittals
should be separated and delivered to FEMA as two requests. LOMR and
CLOMR-F requests are reviewed by different groups at PBS&J. Please be
advised that revisions requested in a CLOMR-F submittal cannot result in
alteration of the floodway. Therefore, the LOMR submittal will have to be
accepted by FEMA prior to the CLOMR-F.
The floodplain elevation tables located m Appendix G show an increase in
the 100-year floodplain elevaiaon fxom existing to proposed conditions at
cross sections 24700, 23800, and 23700. The location of the proposed fill
appears to be in a possible ineffective flow area. ffthe proposed fill will
affect the regulatory lO0-year floodplain elevation, then a CLOIv~ should
be performed, not a CLOMR -F. Revise the modeling to avoid the revision
to the floodplain elevation, or revise the submittal to meet the requirements
for a CLOMR.
06/03/04 THU 15:27 FAX 9722393820 DALLAS ~003
and Associates, Inc.
The Property Information Form states that the CLOMR-F request is for a
single lot. The final plat included in the submlttal shows that the floodplain
reclamation occurs over six lots. If this plat has been filed, then the forms
should be revised to state that the request is for mulhple lots. If the plat has
not been filed, then the current plat should be included in the report.
The Property Information Form states that the entire legally recorded
property is to be removed from the floodplain. The final plat appears to
show that portions of Lots 16 and 17 will remain in the floodplain. The
May 14, 2004 letter to Keith Marvin included a metes and hounds for the
area remaining in the floodplain. However, the CLOIvlR-F instructions
require a metes and bounds description of the area to be removed from the
floodplain. This metes and bounds description should be included with the
CLOM;R-F submittal.
The Elevation Form states that the elevation datum for the survey is NAD
82. NAD 82 is a horizontal datum. Please revise the form to state the
vertical datum for the survey. The vertical datum used for the FEMA
modeling in Dallas County is NGVD 29. If the datum used in this
CLOMR-F is different, please state the conversion factor.
The Riverine Hydrology & Hydraulics Form states that all of the effective,
pre-project, and post-project models can be found in St. Andrews.po, which
is included on the at~ached floppy disk. When this model is loaded, a
message appears stating that many files are missing. The plan files are not
named, and it is difficult to tell which is the existing model and which is the
proposed model. Finally, there are only two plan files on the disk.
Therefore, there cannot be effective, existing, and proposed conditions
models. Include and label digital copies of the effective, existing, and
proposed models for Denton Creek. Also include a hard copy of the
effective model with the report.
A CLOMR-F submittal will not require hydraulic modeling to be submitted
to FEMA, while the LOMR submittal will. However, since the purpose of
the LOMR is only to revise the effective floodway delineation to reflect the
intent of the 1997 LOMR, only an effective model will be required to be
submined to FEMA. No "post-project simulation' models, which model
proposed conditions that have not yet been conslmcted, should be included
in the LOMR. For the purposes of obtaining approvaI of this CLOMR-F
from the City of Coppell, the revisions requested in comments 2 and 6 of
this letter must still be made and approved by the City.
The grading plan prov/ded is not to scale. Please provide a grading plan
that is set to a measurable scale.
Revise the grading plan to illuslrate the grading around the proposed
headwall and show how the floodplain will encroach on this grading,
G:~HY DRO~ROJECTS\63124006\Ltr SA01 .doe
06/03/04 TI]U 15:28 FAX 9722393820 DALLAS ~004
and Associates, Inc.
lO. Provide the proposed flow velocity exiting the headwall during the 100-year
event and detail the erosion conia-ol measures proposed at the headwall.
The floodplain work map shows that the floodplain width at cross section
23500 is approximately 120-feet wide, while the proposed condition table in
Appendix G states that the floodplain width is over 4000-feet. This
discrepancy occurs with every cross section on the work map. Revise the
modeling and the worlanap to have consistent floodplain widths.
12.
The floodplain workmap does not appear to reflect the topographic
information upon which the cross sections in the HEC-RAS modeling were
based. Wherever possible, include the topographic information from the
modeling on the floodplain workmap.
13.
The May 14, 2004 letter to Keith Marvin states that the cross section lines
should be considered schematic, and that the cross sections are meant to be
perpendicular to the flow along Old Denton Creek. The floodplain
workmap should be revised to reflect this intent, and should not be drawn
schematically.
The above comments should be addressed, and the CLOMR request should be
formally submitted for a second review.
Id'you have any questions or comments, please do not hesitate to call.
Sincerely,
KIMLEY-HORN AND ASSOCIATES, INC,
Da~~'¥
Project Manager
cc: J. David Evans, P.E. - Evans Engineering
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