Mansions Phase 1-CS 990706 (5) - FIL
Federal Emergency Management Agency
Washington, D.C. 20472
CERTIFIED MAIL IN REPLY REFER TO:
RETURN RECEIPT REQUESTED Case No.: 99-06-831P
The Honorable Candy Sheehan Community: City of Coppell, Texas
Mayor, City of Coppcll ;. Community No.: 480170
255 Parkway Boulevard Panel Affected: 0010 E --~
Coppell, TX 75019 Effective Date of JUL 0 6 ~999
This Revision:
102-I-A-C
Dear Mayor Sheehan:
This responds to a request that the Federal Emergency Management Agency (FEMA) revise the effective
Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS) report for your community in
accordance with Part 65 of the National Flood Insurance Program (NFIP) regulations. In a letter dated
February I, 1999, Mr. Rusty Splats, P.E., Vice President, Dunaway Associates, Inc., requested that
FEMA revise the FIRM and FIS report to show the effects of placement of fill, grading, and excavation
of two ponds associated with the Mansions by the I. ake ~development along Denton Creek from
approximately 2,570 feet downstream to approximately 540 feet downstream of State Highway 121
(SH121). Expansion and contraction coefficients and ineffective flow areas were added to the hydraulic
model for Denton Creek in the vicinity of SH121 to show the effects of the SH121 bridge. In addition,
this request included more detailed topographic information from approximately 3,840 feet downstream
to just upstream of SH121 and the effects of an existing pond located just downstream of the project. This
request follows up on a Conditional Letter of Map Revision issued on February 10, 1998.
All data required to complete our review of this request were submitted with letters from Mr. Kenneth M.
Griff'm, P.E., Director of Engineering and Public Works, City of Coppell; Mr. T. S. Kumar, P.E.,
Assistant City Engineer, Floodplain Administrator, Depaxtment of Community Development, City of
Lewisville; and Mr. Spiars.
We have completed our review of the submitted data and the flood data~ shown on the effective FIRM and
FIS report. We have revised the FIRM and FIS report to modify the elevations and floodplain and
floodway boundary delineations of the flood having a 1-percent chance of being equaled or exceeded in
any given year (base flood) along Denton Creek from approximately 3,290 feet downstream to just
downstream of SH121. As a result of the modifications, the base flood elevations (BFEs) for Denton Creek
decreased and the widths of the Special Flood Hazard Area (SFHA), the area that would be inundated by
the base flood, and the regulatory floodway increased in some areas and decreased in other areas. The
modifications are shown on the enclosed annotated copies of FIRM Panel(s) 0010 E, Profile Panel(s) 09P
and 10P, and affected portions of the Floodway Data Table. This Letter of Map Revision (LOMR) hereby
revises the above-referenced panel(s) of the effective FIRM and the affected portions of the FIS report,
both dated April 15, 1994.
Page 1 of 10
2
Because this revision request also affects the City of Lewisville, a separate LOMR for that community was
issued on the same date as this LOMR.
The modifications are effective as of the date shown above. The map panel(s) as listed above and as
modified by this letter will be used for all flood insurance policies and renewals issued for your community.
The following table is a partial listing of existing and modified BFEs:
Existing BFE Modified BFE
Location (fee0* (fee0*
Approximately 250 feet downstream of SH121 467 466 ....
Approximately 2,570 feet downstream of SH121 466 465
*Referenced to the National Geodetic Vertical Datum, rounded to the nearest whole foot
Public notification of the proposed modified BFEs will be given in the Citizen's Advocate on or about
August 13 and August 20, 1999. A copy of this notification is enclosed. In addition, a notice of changes
will be published in the Federal Register. 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. Ail 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.
Because this LOIVIR 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.
We are preparing a revised FIRM and HS report for Dallas County in our countywide format; therefore,
we will not physically revise and republish the FIRM and FIS report for your community to incorporate
the modifications made by this LOMR at this time. Preliminary copies of the countywide FIRM and FIS
report, which will present information from the effective FIRMs and HS reports for your community and
other incorporated communities in Dallas County, will be distributed for review in summer 1999. In order
to avoid delays in processing, we will not incorporate the modifications made by this LOMR into the
preliminary countywide FIRM. However, we will incorporate these modifications into the countywide
FIRM and HS report before they become effective.
The floodway is provided to your community as a tool to regulate floodplain development. Therefore, the
floodway modifications described in this LOMR, while acceptable to FEMA, must also be acceptable to
your community and adopted by appropriate community action, as specified in Paragraph 60.30) of the
NFIP regulations.
Page 2 of 20
This LOMR is based on minimum floodplain management criteria established under the NFIP. Your
community is responsible for approving all floodplain development, and for ensuring all necessary permits
required by Federal or State law have been received. State, county, and community officials, based on
knowledge of local conditions and in the interest of safety, may set higher standards for construction in the
SFHA. If the State, county, or community has adopted more restrictive or comprehensive floodplain
management criteria, these criteria take precedence over the minimum NFIP criteria.
The basis of this LOMR is, in whole or in part, a channel-modification project. NFIP regulations, as cited
in Paragraph 60.3(bX7), require that communities ensure that the flood-carrying capacity within the altered
or relocated portion of any watercourse is maintained. This provision is incorporated into your
community's existing floodplain management regulations. Consequently, the ultimate responsibility for
maintenance of the modified channel rests with yodf 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 90448),
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 minimum NFIP criteria. These criteria are the minimum and
do not supersede any State or local requirements of a more stringent nature. This includes adoption of the
effective FIRM to which the regulations apply and the modifications descn'bed in this LOMR. Our records
show that your community has met this requirement.
A Consultation Coordination Officer (CCO) has been designated to assist your community. The CCO will
be the primary liaison between your community and FEMA. For information regarding your CCO, please
contact:
Mr. Frank Pagano
Director, Mitigation Division
Federal Emergency Management Agency, Region VI
Federal Regional Center, Room 206
800 North Loop 288
Denton, Texas 76201-3698
(940) 898-5127
FEMA makes flood insurance available in participating communities; in addition, we encourage
communities to develop their own loss reduction and prevention programs. Our Project Impact initiative,
developed by FEMA Director James Lee Witt, seeks to focus the energy of businesses, citizens, and
communities in the United States on the importance of reducing their susceptibility to the impact of all
natural disasters, including floods, hurricanes, severe storms, earthquakes, and wildfires. Natural hazard
mitigation is most effective when it is planned for and implemented at the local level, by the entities who
are most knowledgeable of local conditions and whose economic stability and safety are at stake. For your
information, we are enclosing a Project Impact Fact Sheet. For additional information on Project Impact,
please visit our Web site at www.f~-ma.gov.
Page 3 of l0
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If you have any questions regarding floodplain management regulations for your community or the NFIP
in general, please contact the CCO for your community at the telephone number cited above, ff 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,
Alan A. Johnson, P.E., Project Engineer :' For: Matthew B. Miller, P.E., Chi¢lf
Hazards Study Branch ~ Hazards Study Branch
Mitigation Directorate Mitigation Directorate
Enclosure(s)
cc: The Honorable Bobbie J. Mitchell
Mayor, City of Lewisville
Mr. Kenneth M. Griffin, P.E. ~/
Director of Engineering and Public Works
City of Coppell
Mr. T. S. Kumar
Assistant City Engineer
Floodplain Administrator
Depa,i,slent of Community Development
City of Lewisville
Mr. Rusty Spiars, P.E.
Vice President
Dunaway Associates, Inc.
Page 4 of 10
CHANGES ARE MADE IN DETERMINATIONS OF BASE FLOOD ELEVATIONS FOR THE CITY
OF COPPELL, DALLAS AND DENTON COUNTIES, TEXAS, UNDER THE NATIONAL FLOOD
INSURANCE PROGRAM
On April 15, 1994, the Federal Emergency Management Agency identified Special Flood Hazard Areas
(SFHAs) in the City of Coppell, Dallas and Denton Counties, Texas, through issuance of a Flood Insurance
Rate Map (FIRM). 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 this community is appropriate. The modified base flood elevations (BFEs) revise the FIRM
for the community.
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 Nation,il Flood Insurance Act of 1968, as amended (~l'ifle 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 placement of fill, grading, and excavation of two ponds
associated with the Mansions by the Lake development; addition of the State Highway 121 bridge to the
hydraulic model for Denton Creek; and more detailed topographic information from approximately
3,840 feet downstream to just upstream of State Highway 121. This has resulted in a revised delineation
of the regulatory floodway, increases and decreases in SFHA width, and decreased BFEs for Denton Creek
from approximately 3,290 feet downstream to just downstream of State Highway 121.
Existing BFE Modified BFE
Location (fee0* (feet)*
Approximately 250 feet downstream of State Highway 121 467 466
Approximately 2,570 feet downstream of State Highway 121 466 465
*National Geodetic Vertical Datum, rounded to nearest whole foot
Under the above-mentioned Acm of 1968 and 1973, the Mitigation Directorate must develop criteria for
floodplain management. To participate in the National Flood Insurance Program (NFIP), the community
must use the modified BFEa to administer the floodplain management measures of the NFIP. These
modified BFEs will also be ~ 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 Officer of the community, 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.
Page 5 of~.~ ~"
2
Any person having knowledge or wishing to comment on these changes should immediately notify:
The Honorable Candy Sheehan
Mayor, City of Coppell
255 Parkway Boulevard
. Coppell, Texas 75019
Page 6 of 10
) -/ ZONE X
.=,. -=. ,.,==DENTON COUNTY ,'~ ....
~/// /:....._.... DALLAS COUNTY tNEAE ZONE X
q! ,ff.?.:~ ZONE X X
FIPJ
AUBURN WAY
ZONE X MARKED TRF..E TRAIL
FL000 INSURANCE RATE MAP ZONE X
and
STREET INDEX
CITY OF I ZONE AE
£OPPELL, THIS AREA WAS REVISED BY
JVU~p
LEGEND
i~ HOLLOW LANE
MAP REVISED: ~[ 0 N E X '!:5
APPROXIMATE 5,CALE O ~ · ',, RM 197;~ ".i!
1000 0 1000 FEET ~'". '
BASE FLOOD
FLOODING SOURCE FLOODWAY WATER SURFACE ELEVATION
SECTION MEAN I WITHOUT I WITHI
WIDTH AREA VELOCITY REGULATORY FLOODWAY FLOODWAY INCREASE
CROSS SECTION DISTANCE (FEET) (SQUARE (FEET PER
FEET) SECOND) (FEET NGVD)
Denton Creek
A ).9 452.4 452.4 453.4 1.0
B 22,7C 263 3,182 [.-'~~a"~a.'~'~ 452.7 ~ 453.6 0.9
· D 29,280t 1,134 8,383 2.5 456.3 456.3 /,57.0 [ 0.7
REVISED DATA --._.~. E I 36' ?60ti 849{ 5,686 [ 2.7 [ 465.4[ 465.4 [ 465.9I
F 39,200~[ 499 3,2.98 3.2 468.3 468.3 468.8 0 5
Cottonwood Br~nch
^ 3,850~ 356 1. 780 4.1 t~63.7 463.7 t, 6t,. 5 O. 8
B 6,?10~ 587 I 2,34O 3.~ ~*0.1 470.0 470.7 0.7
THESE DATA WERE REVISED BY I--
LOMR DATED JANUARY 2.6, 1996
? REFLECT LOMR
~ 1Feet; above confluence with Elm Fork of Trinity River
~ 2Feet above confluence with Denton Creek
O.~,... *Data ,,o, DATI:I1JuL 06 mss
'"""1 FEDERAL EMERGENCY MANAGEMENT AGENCY FLOODWAY DATA
m,.. CITY OF COPPELL, TX ~
Irt (DALLAS & DENTON COS.) NTON CREEK - COTTONWOOD BRANCH
· . ~...,c~.~c~.-.m,~,,-,,,,~,~--,-:~r"c'"-- 1..---_- .---=..~-_---:"-'.~--_
480 THIS REACH WAS REVISED BY 8 ~ - Z ~ .... ~ .... -- I~ ~ -- --
uJ ! [ i REVISED REACH
-- · · .O-- ~) THIS REACH WAS REVISED BY i ~ '
i LOMR DATED JULY 23, 99? O __ __ . .... I -- Z +_~-.-,,_
! ' : ..... :[--' t LOMR DATED JANUARY 25, 1995 "" _ __ -I r .... + ............
470 STATION 25,520 = STATION 26,220 i i .... : ; ! ,
/ -
.... -,-'- ; :, i ............. ~ ............................. ~- ..........~-~-
. -- '"- _7 .............. i.' .............. olo
I
........... ~_ ~ , , . .
i ...... '-~'::::::::'-"- ---:: :: - i-' :-::'-':---': :. :: :-::.:.-:' .::: :.- .....
............. , ............. --- :-: .....~-YEAR FLOOD
......... ' ...... ~ ............. =, ........................ 100 - YEAR FLOOD
; .......... , ...... I I i1- ........... T .............. 50- YEAR FLOOD
~ .......... ~ ............... CROSS SECTION
26 27 28 29 30 31 32 33 34 '§5 36 37 38
STREAM DISTANCE IN THOUSANDS OF FEET ABOVE CONFLUENCE WITH ELM FORK OF TRINITY RIVER
Pale
' i t ! I ~ , .-J-4-j~ $--,-4--+ ! tt ~ ~
' ' j J j i J~-~; ~
' 4~ ~ ~ ,~-~-~ ~. ~
, ~ ~ ' ~ 470 ~
470 i -- r, j ~ ~ ~
.j , .~ 'j ij~ ~
.. .,.j.,j ...., ,. ~ ~ ~
~ ' ~ J ~l j 450 ~
450 I J j , J
~: :'", ~ i , ' t ' ~
' j , ,,
445 J ~ ~,~~ ; I ~
' ~ LEGEND I ~ ~
: ~1 ~ '. I ~; 'J j . ; '
, , ' =~-=~i' j j ~ STRetChED --m
-~ -I 11 I ;[, ........ , , ~ ~
' '~ ......... , i''l ~i4~- i: Il '- ..... :r:, ~'
I ; , ; .,~,. ........ u._.~_f+.ff.~_ +.~.~ ....... . ~ i. ............ ~-~- ' i ~ . ~; ...... ......... ++-..~' f ! ~. LOCATION j ~
~ I I ' ~ ~ ............ T~+~ .... ~ ........ t ~ :, : ; ~ ,. : i, . , · ................
435 ~ .......... ~ ~
39 40 41 42 43 44 45 ~ 47
STREAM DISTANCE IN THOUSANDS OF FEET ABOVE CONFLUENCE WITH ELM FORK TRINI~ RIVER 10P
Page tO of ~0 ~