St Andrews Est-AG040706AGENDA REQUEST FORM
COFPELL
DEPT: Engineering
DATE: July 6, 2004
ITEM #: 7/E
ITEM CAPTION:
Consider approval of a variance to Floodplain Management Ordinance No. 94-639, Article 4, Section B, Item
11 (a), which states that the Floodplain Administrator must "assure that conditional approvals are received from the
Federal Emergency Management Agency before a Floodplain Development Permit is issued" for the proposed St.
Andrews Estates along Old Denton Creek.
APPROVED BY
CITY COUNCIL
ON ABOVE DATE
IIII
GOAL(S):
Motion to Approve
M - Peters
S - York
Vote - 6-0
Tunnell absent
EXECUTIVE SUMMARY:
Approval of this variance to Floodplain Management Ordinance No. 94-639 will allow the developer to begin the
reclamation process now for St. Andrews Estates while the study is being reviewed by FEMA.
Staff recommends approval and will be available to answer any questions at the council meeting.
FINANCIAL COMMENTS:
Agenda Request Form - Revised 02/04 Document Nam( #FloodplainVar-lAG
MEMORANDUM
FROM THE
DEPARTMENT OF ENGINEERING
To~
From:
Date:
RE:
Mayor and City Council
Kenneth M. Griffin, P.E., Director of Engineering/Public Works
July 6, 2003
Consider approval of a variance to Floodplain Management Ordinance No.
94-639, Article 4, Section B, Item ll(a), which states that the Floodplain
Administrator must "assure that conditional approvals are received from the
Federal Emergency Management Agency before a Floodplain Development
Permit is issued" for the proposed St. Andrews Estates along Denton Creek.
St. Andrews Estates is located north of Deforest Road with Denton Creek being both north and
west of the proposed development. Currently, a portion of the floodplain of Denton Creek
encroaches on the property. In May 2004, a floodplain study for reclamation was submitted to
this office and on May 10, 2004, the flood study was processed to our consultant for review for
compliance with the city's floodplain ordinance and with Federal Emergency Management
Agency (FEMA) guidelines. The flood study meets our requirements and has been sent to
FEMA. Prior to work beginning on the project, the City must issue a Floodplain Development
Permit to the developer. However, the Floodplain Management Ordinance states that a permit
cannot be issued until conditional approvals are received from FEMA.
The developer is requesting a variance from the Floodplain Ordinance so that the reclamation
process can begin now. As stated to the developer, the reclamation cannot begin until a
Conditional Letter of Map Revision (CLOMR) has been received from FEMA and the city has
issued a Floodplain Development Permit. The study has been sent to FEMA and it typically
takes six to eight weeks to receive the CLOMR from FEMA.
This variance request is submitted with the following stipulations: 1) a letter is provided from
FEMA stating that they have all the necessary information to proceed with the review of the
flood study; 2) any changes requested by FEMA during the flood study be complied with prior to
acceptance by the city; and 3) no building permits will be issued on any lots within the
subdivision until the study has been approved by FEMA.
Previously, the City has granted similar variances to Big Cedar subdivision and Villages of
Coppell Phase 3B. Compliance with the above stipulations will be monitored by staff.
Therefore, staff recommends approval of this request and will be available to answer any
questions at the council meeting.
"CITY OF COPPELL ENGINEERING - EXCELLENCE BY DESIGN"
10.
11.
flooding in light of the need to prevent environmentally incompatible floodplain
use; and encourage floodproofing of existing floodplain developments.
Make full disclosure to all interested parties that:
a. Certain structures are located within floodplain areas;
b. Variances have been granted for certain developments or structures; and
Data is available which shows special flood hazard area and floodplain
management area information for the City.
Prepare and maintain flood warning and emergency preparedness plans which
include:
a. Provision for alternative vehicular access and escape routes; and
Minimum floodproofing and access requirements for schools, hospitals,
nursing homes, orphanages, penal institutions, fire stations, police stations,
communications centers, water and sewage pumping stations, and other
public or quasi-public facilities to enable them to withstand flood damage,
and to facilitate emergency operations.
Enforce improvements to local drainage within new developments to control
increased runoff that might increase the danger of flooding to users of the
development or of flood hazards to users or other properties adjacent to,
downstream or upstream of the development. This includes the use of detention
basins to limit mnoffto predevelopment levels.
Coordinate CiD' floodplain management programs with State, regional and
neighboring community floodplain management programs.
Require floodplain development permits for all new construction or development
in floodplain management areas of the City.
Assure that conditional approvals are received fi.om FEMA before a
Floodplain Development Permit is issued. Upon written acknowledgement
of receipt by FEMA of the required technical data, construction may
commence within a floodplain area provided the person performing such
development furnishes a written agreement to assume the cost of any
modifications noted by FEMA, as a result of their technical reviews, to be
required for proper completion.
Require the developer to submit an as-built technical report of floodplain
development conditions as soon as work affecting the floodplain is
18
T H E C I T Y 0
FLOODPLAIN DEVELOPMENT PERMIT
PERMIT NO. 0'30-/04 T' ~
The above named permitee applied for a FLOODPLAIN DEVELOPMENT PERMIT on
The application has been reviewed by ~e FLOODPLAIN ADMINSTRATOR and it has been determined ~at the proposed
development is located within an identifiable floodplain of:
The FLOODPLAIN ADMINISTRATOR has reviewed pl~s ~d specifications of ~e proposed development for
conformance wi~ ~e development st~d~ds required by COPPELL Floodplain Ordinance ~94639. You are hereby
au~orized to proceed with the following described work:
To maintain compliance with the development standards of COPPELL Floodplain Ordinance #94639 and to eliminate or
minimize flood damage potential to the proposed development, you are hereby directed to construct your proposed
development in accordance with the following special provisions:
~ development standards of Coppell Floodplain Ordinance//94639 including but not limited to:
Compliance
the
· For residential structures, the lowest floor (including basement) must be elevated to two (2) feet above the 100-
year base flood elevation or one (1) foot above ultimate condition whichever is higher. Certification of the
lowest floor must be submitted from a registered professional engineer, architect, or land surveyor.
· For non-residential structures, the lowest floor (including basement) must be elevated or floodproofed to two
(2) feet above the I00-year base flood elevation or one (1) foot above ultimate condition whichever is higher.
Certification that the floodproofing methods are adequate to withstand the flood depths, pressure, velocities,
impact and uplift forces and other factors associated with the base flood must be submitted from a registered
professional engineer or architect.
Certified copy of all Final plans
ADMINISTRATOR.
~ISION$:
For fill activities, the permittee must submit certification from a r~
surveyor that the level of the compacted fill materials is at or above the
or As-Built Drawings must
Acknowledgeme~)Conditions by Permittee
Signliture of FLOODP~.~IN ADMINISTRATOR
Printed Nam,
Printed Nam~
;istered professional engineer or land
~levation of the Base Flood.
submitted to the FLOODPLAIN
Date
Date
The Holmes Builders
June 28,2004
VIA FACSIMILE
City of Coppell
Engineering Department
255 Parkway Blvd.
Coppell, TX 75019
Attn: Paula Crocker
Re: St. Andrews Development
Dear Paul&
We would like to request a variance to the Floodplain Management Ordinance No. 94-
639, Article 4, Section B, Item 11(a), for St. Andrews Estates based upon following
conditions:
1. The floodplain study meets the city's floodplain requirements.
2. A letter is provided from FEMA stating that they have all the necessary
information to proceed with the review of the flood study
3. And change requested by FEMA during the flood study be complied with prior
to acceptance by the city.
No building permits will be issued on any lots within the subdivision until the
udy has been approved by FEMA.
Terry Holmes
President
FAX COVER SHEET
The Holmes Builders
1406 HALSEY WAY SUITE 100
CARROLLTON, TEXAS 75007
OFFICE 972'242'1770
FAX - 972-242-2931
theho[mesbuilders.com
SEND TO
Company Name
City of Coppell - Engineering
j Jon Dostert
Attention: Date
Pauta Crocker 6/28/2004
Office Location Emai[
jdostert@theholmesbuilder$.com
Fax Number Phone number
972-304-3570 972~242-1770 ext 209
[] Urgent [] For Review [] Please Comment I~ Please Reply [] Please Recycle
COMMENTS
Kimley-Horn
and A88ociates, Inc.
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
KHA No. 063124006
Dear 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. KHA
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 (CLOMR-
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 in Appendix G show an increase in
the 100-year floodplain elevation from 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. If the proposed fill will
affect the regulatory 100-year floodplain elevation, then a CLOMR 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.
·
Suite 1800
12700 Park Central Drive
Dallas, Texas
75251
TEL 972 770 1300
FAX 972 239 3820
~]ll~ Kimley-Horn Mr. Kenned~M. Griffin,?.E,Jm,c3,2004,?age2
and Associates, Inc.
~Une Property Information Form states that the CLOMR-F request is for a
single lot. The final plat included in the submittal 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 multiple lots. If the plat has
not been tiled, 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 bounds for the
area remaining in the floodplain. However, the CLOMR-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
CLOMR-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 StAndrews.prj, which
is included on the attached 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
submitted to FEMA. No "post-project simulation" models, which model
proposed conditions that have not yet been constructed, should be included
in the LOMR. For the purposes of obtaining approval 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 provided is not to scale. Please provide a grading plan
that is set to a measurable scale.
Revise the grading plan to illustrate the grading around the proposed
headwall and show how the floodplain will encroach on this grading.
G :\HYDRO,PROJECTS\63124006\LtrSA01.doc
Kimley-Horn Mr. Kenneth M Grlffin, P.E.. Jm~e 3, 2004, Page 3
and Associates, Inc.
10. Provide the proposed flow velocity exiting the headwall during the 100-year
event and detail the erosion control measures proposed at the headwall.
11.
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 workmap 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.
If you have any questions or comments, please do not hesitate to call.
Sincerely,
KIMLEY-HORN AND ASSOCIATES, INC.
Project Manager
Cc: J. David Evans, P.E. Evans Engineering
G:\HYDRO~PRO JECTS\63124006\LtrSA01 .doc