Vista Plex-CS 861224CAFFEY AND MORRISON, INC.
ENGINEERS -- HYDROLOGISTS
DecemeDer 24, 1986
,
Ms. Maryetta Cunningham
National and Technological Hazards Division
Federal Emergency Management Agency
Region VI Federal Center
800 North Loop 228
Denton, Texas 76201-3698
RE:
Proposed development project along Denton Creek north
of Sandy Lake Road in Coppell, Dallas County Texas.
Dear Ms. Cunningham:
Before discussing the subject project I want to thank you
for your concern and help at our meeting of December 22,
1986. As always, your conscientious attitude makes our work
in the private sector much easier.
This project is a bit complicated since it is in an area
presently under study Dy the Corps of Engineers and FEMA. A
brief explanation of the actions taken or expected would
help clarify the status of the project.
1. In late 1984 FEM3% contracted with the Fort Worth
District Corps of Engineers to perform a Flood Insura-
nce study (FIS) of Lewisville, Texas. During the
course of this study it was discovered that there were
inaccuracies in the present study of the Elm Fork of
the Trinity River through Lewisvi!le, and several
other cities. One of these other cities was Coppell,
Texas. Because of this, FE~LA decided to add a study
of the Elm Fork of the Trinity River to the Lewisville
FIS. The results of the Lewisville FI$ and the Elm
Fork of the Trinity River were submitted by the Corps
to FEMA on September 30, 1986 (attachment 1).
2. FEMA's consultant Dewberry and Davis reviewed this
FIS and completed the review on December 22, 1986.
This is according to information provided by Dave
Loshbough of Dewberry and Davis. The review results
are not known at this time. However, Mr. Loshbough
stated that Dewberry and Davis did not have any
questions through the area of our referenced project.
We can assume from this that the Corps correctly
modeled this area.
2212 ARLINGTON DOWNS RD., SUITE 105 ARLINGTON, TEXAS 78011 (817) 649-8110 METRO 640-8101
Caffey and Morrison, Inc.
Coppell, Texas
December 24, 1986 page 2
According to the New (1986) Natiional Flood Insurance
Program (NFIP) Part II 44CFR, part 60, paragraph 60.3
(b) (4) a community must "obtain, review and reasonab-
ly utilize any base flood elevation and floodway data
available from a Federal, State or other source". We
discussed this provision and we understand your
thoughts are that once the preliminary data is presen-
ted by FEMA, the ciuy should use it unless they think
there are errors in the data.
We have an appointment with Ms. Shohree Daneshmand of the
City of Coppell on January 7, 1987 to discuss the referenced
project. However, Mr. Ed Powell, the former City Engineer,
has reviewed our project and our flood study of the area and
has stated the city's approval (attachment 2). FEMA has
also reviewed our flood study and they consider it as the
"best available data" until the Corps/FEMA FIS is made
available. (attachment 3).
Based on all of this we would very much appreciate it if
FEMA could provide Coppell with their preliminary study as
soon as possible. Since our study, the Corps and FEMA all
agree that there are no errors in the Coppell portion of the
study.
Thank you for your help in this matter. If we can provide
any additional information do not hesitate to call.
rely,
~~Morrison, P.E.
Vice President
attachments
ATTACHMENT 1
planning
P. o. ~ox 17~oo
FORT WORTH. TEXAS 76102-0300
September 30, L986
Division
OCT 2 ....
Mr. Charles A. Lindsey
Federal Emergency Management Agency
office of Risk Assessment
Washington, D.C. 20472
Dear Mr. Lindsey:
The follow~_ng deliverable it=-~ au~ backup materials for the
Elm Fork Trinity River which are being done as a Fm-~t of tire
Flood Insurance Study for the ci~t of Le~risvJ_Lle, Denton CounT/,
Texas are beLng suh~tned dir-~--- to Dewberry & Davis as
ir~ac--~ed Ln ,;our letter dated July 24, 1984. This information
is to ke used %o a~nd t~he maps for the cities of Ccppe!!,
=Carrel!ton, Fa~r.~.ers Branch, I-~-~i~-g, a~ Dallas, T~xas.
a. OrigL~a!s of rine combined FB=-~JF~M work waps for t_he Elm
Fork Tr-L~--~ il; River covering the area from its confluenca with t2ne
TrL-h~t .River to rite Le,.~%svit!e city limits.
b. Copies of al! ~hles a~ origLn~l vicinity map.
c. OrigL~-ls of ~e flood profiles.
d. Copies of hydrologic a~ hydraulic a~z~lysis ccm~_uter
printouts ~or tire ~hm Fork Trirhtv ~iver for ti~e srmeam reach
from i~-~ confluence' witln t,%e TrL~ty to d~,ns~ream of L~ke
Lewisville dam.
e. G~.e copy of tire study Car-~-ificar-i°n-
CoPies of al! ~hLes, flood profiles, and :~rk maps ~have
be~_n s~.t to ti%e CCO in Denton, Texas.
sincerely,
Mic,%ael A. Moc=~'~, P.E.
Ckief, Pla~_ng Division
E~c!osures
Copy Furnished:
Dewberry & Davis w/enClosures
¢CC0, FEMA w/enclosures
DAEN-~P-F we/enclosures
SWDPL-M we/enclosures
TABLE I
....... rLmll, l,dAY .,- UATF. R Suflr-ACr. ELF. VAT'TON
AIIE~ VELOCI. T l FLOOD~ RY FLOOI]UA¥
A
5050.0g0 lq~. ~O~O. Io~
l~OmOoO00 13~. 3"~1r~. 1.q
tmo?~.ooo t557. 1~721. 2.5
lq~O.O00 I~Goo 2';30n, 1.?
1~5~0.000 lmGm. 2~?f}. 1.{1 mm~.G
I7360,000 lnl3. 377qn. l.~
18520.000 m6mt. ?m25~, 0.6
~1000.000' ~,10~1. ~l~n~ ,. ~v?
22~70.000 251°* ~270~. 1.3
225?0.000 2~t~. 3ZTmOo I.~
2fi300,000 253%* · 1~603, 1.3
29000.0~0 I~R"° 2~777, 1,7
29~20,000 1}I~0o. 2~tO, l,?
2~560o000 1~50. Yt~om. l.~ m?6.1
-3q160,000 .$L50, 30057, l*? m27,2
3qi~OoO00 3150, 23675, l°n
3q230,OqO tl50. 23700, l,a m~7,2
~q2~O.O00 3150. 3~21. l.~
· 37310.000 2n~O. l~Olt, 3.0
3r350,000 3000, 37n~3, 1,~
~3010,000 2~tq. 2tmon, lo?
~qOOO.O00 30On. 2r~';. I,G
~mt§O.O00 306'{. 2m130. l,q
57t?O.o00 .i~o0. 130'}6o 3.? 037.t
§q2rO.OOO lOgO. q{t07, ?.~!
0o0
0,0
0o0
0.0
0°0
0.0
0o0
0.0
0o0
0o0
0o0
O,t
0.3
0.3
0,2
0,3
0,?
0,3
0°3
....... F L!Utf)UAY ----~ ---
AqEA V~LOCIfT
~&T~.R SURFACE 5LEvar[a~
UIrHOUT UIIH Ol FFERC. NC~'.
FLOODWAY FLOOOUAY
62q~0.~9 llnl.
6~00,000 I~0~,
680q0,000
6ROOO.O00
6~qO,OqO
T12qO,O00 2~01J,
72q?O.OOO 3591.
756~0,300
77~90,000 .$2~q-
87ROO.OOO
87930,000
8RO00.O00 5~2~.'
R~050.000 5:33~.
q~OqO,O00 6120.
93620,000
~3670.000 STOO*
937J0,000 §qO0.
93T60,000 ~00o
97570,000 7600,
~: . --~r'- 'T~
PROFILE NO. 2
q33,7 ~ lt.'~ 0.2
{.13.n ~5~.0 0,2
~,13.~ ~J~.[
~ ,l,l. '~ 4J~. [ 0.2
~?-I ~ ~'-[ ~.0
~ lq,J ~ )q.J 0.0
STATION
UIIJTll SFCT lO~ ~FaN
ArEA VELOCITY
~ITItlll)f WIfll OIFFERE'ICE
FLOOOUAY FLOOOUAY
FLOODWAY DATA,
-PROFILE NO. 2
ELM FORK TRINITY RIYER
STATION WIOTH
SE:TION' MEaN
VE: O%ITT
~TER SURFACE
WITHOUT WITH OIFFE~E~CE
FLOOOWA~ FLOOOW~
20185. l.O ~60o8
,.PROFILe' NO. 2 .-
: .... FLOODWRY
-- ST~TION , "-WIDTH SECTION
WITHOUT WITH
~ . 0~0
4200 · 000
S2'~0. 000
.20420.000
104~0. 000
EOT..
1~2.
1C',±,.
92.
?0.
~,' . 7.J
~ 12 · 7 · 4
S~O . i'3.~
4r/ . ~.i
---r , , .i
~l~· !u.u
....' 11.2
- - ·
127. 1.". 7
~=5. 9.0
~ <:
(....) =
-,4 -~
ATTACHMENT 2
The City With A Beautiful Future
p, O. 8(3x 478
~3~3oetl, Texas 75(319
214 · 462.0(]22
July 3, 1986
Federal Emergency Management Agency
Federal Insurance Administration
Office of Risk Assessment
Risk Studies Division ~
500 C Street S.W.
Washington, D.C. 20472
Re: Flood Insurance Study Revision along the Elm
Fork Trinity River in Dallas, County, Coppe!!,
Texas (Vistoplex Development on Sandy Lake Rd.)
· Attention: Mr. Matt ~ller
Dear Mr. Miller:
The City of Coppell has received a Technical Report from
the consulting engineering firm of Caffey and Morrison,
Inc., on the existing and proposed flood plain and
floodway conditions along the Elm Fork Trinity River,
adjacent to Sandy Lake Rd., Coppell, Texas. This
report, prepared by Caffey and Morrison, Inc., includes
a. ~etailed hydraulic analysis of the existing channel
and overbank conditions, as well as proposed improve-
ments. The report also includes ~ne HEC-Z computer printout,
flood plain and flood way maps and possible revisions
of the existing flood insurance maps. It is our under-
standing that this same information has already been
submitted to your office for review. The City of
Coppell has reviewed,this material and agrees with its
content~
If you have technical questions about this report,
please contac= Mr. Ron Morrison, P.E., with Caffey and
Morrison, Inc. (1-817-649-8110). Any administrative
questions should be directed to the office (1-214-462-
0022).
Thank you for your consideration of this very important
request.
Sincerely,
~/W.. Powe!l, P.E.
~ity ~ngineer
cc:
Mr. Wayne Ginn, P.E., Ginn, Inc.
· Mr. Ron Morrison, P.E.,~Caffey and Morrison, Inc.
Mr. Bill Kuno, Federal ~mergency Manqement
Agency, Re~ion IV
Federal Emer§enc ; Management Agency
Washington, D.C. 20472
December 12, 1986
The Honorable Lou Duggan
Mayor of the City of Coppell
P.O. Box 478
Coppell, Texas 75019
Dear Mayor Duggan:
This is in reference to a letter dated May 23, 1986, submitted by Mr. Ronald
W. Morrison, P.E., Vice President of Caffey and Morrison, Inc., concerning the
Flood Insurance Study (FIS) for your community. In his letter, Mr. Morrison
requested that the Federal Emergency Management Agency (F~"~A) revise the FIS
for your community based on a revised hydraulic analysis of the Elm Fork of
the Trinity River in the vicinity of Sandy Lake Road and Denton Creek, pre-
pared by Caffey and Morrison, Inc. Mr. J. E. Powell, P.E., City Engineer for
the City of Coppell endorsed Mr. Morrison's request in a letter da=ed July 3,
1986.
with his letter, Mr. Morrison sul~mitted a technical report prepared by Caffey
and Morrison, Inc., entitled A Flood Insurance Stmd~ Revision of ~1~ Fork
of the Trinity River in Co~ell, Texas, da~ed May 10, 1986. This report
contained a description of the methodologies used, flood boundary maps,
plotted cross sections and water-surface profiles, and ~EC-2 backwater models
of the Elm Fork of the Trinity River. ;~tditional data submitted at our
request by Ca'fey and Morrison, Inc., on October 13, 1986, included a revised
HEC-2 backwater model and additional documentation of t_he methodologies and
parameters used in the hydraulic analysis.
The For= Worth District, U.S. Army Corps of Engineers (COE), under contract to
F~MA, has developed a comprehensive HEC-2 backwater model of the Elm Fork of
the Trinity River from its confluence w~th the West Fork of the TrinityRiver
to Lewisville Lake. Based on the COE's analysis, we will be revising the FIS,
Flood Boundary and Floodway Map (FBFM}, and Flood Insurance Rate Map (FIRM)
for your oommuni~f. Therefore, 'we compared the HEC-2 model prepared by Caffey
and Morrison, Inc., to the COE's HEC-2 model. Although some of the hydraulic
parameters differ from the COE's HEC-2 model, w~ believe that Caffey a~q
Morrison's HEC-2 model is conservative; therefore, t/lis model can be used as
the best available data for flondplaln management purposes frem approximately
2,050 feet upstream of Bel~l~ne Road to approximately 6,250 feet upstream of
Sandy Lake Road until we revise the FIS, FBFM, a~Jt FIRM for your C~-m,mity to
reflect the results of the COE's analysis. However, the zone designations on
the current effective FIRM will continue to be used to establish flood in-
surance rates un~il a revised FIRM becomes effective. Likewise, the floodway
designations on the effective FBFM will remain in effect for regulatory
purposes.
Should you have any questions regarding t_his matter, please do not hesitate
contact ~he Chief, Na=ural and Technological Hazards Division of the Federal
Emergency Management Agency in DenOn, Texas, at (817) 898-S~17 or members of
our Headquarters staff in Washington, D.C., at (202) 646-2754.
Sincerely,
Studies Division
Federal Insurance ~-~ n!stration
cc: Mr. Michael A. Mocek, P.E., Chief, Planning Division, For= Worth
District COE
Mr. Ronald W. Morrison, P.E.
Mr. J. E. Powell, P.E.