WA9902-CS001127November 27, 2000
Mr. Kenneth M. Griffin, P.E.
Director of Engineering and Public Works
City of Coppell
255 Parkway
P.O. Box 478
Coppell, Texas 75019
Re: Computation of Flood Storage for a 2 Acre Site South of Sandy Lake Road and East of McArthur
Blvd. in the Elm Fork of the Trinity River Floodplain in Coppell, Texas.
Dear Mr. Griffen:
We are pleased to provide this report to identify the required storage compensation needed to fill a 2 acre
site to one foot above the 100 year design floodplain as determined from the 100 year and Standard Project
Flood (SPF) as computed by the Corps of Engineers and reviewed by the Federal Emergency Management
Agency (FEMA), and currently awaiting final approval to calculate storage compensation. The storage
compensation allows a 15% reduction in 100-year flood storage and a 20% reduction in the Standard
Project Flood (SPF).
The drawing below shows the site.
Using the new floodplain information the existing and developed volumes of storage were calculated. They
are as follows:
100-year existing condition volume N/A above 100-year
SPF existing condition volume 3.32 acre-feet
100-year existing condition allowable volume N/A above 100-year
SPF existing condition allowable volume 2.66 acre-feet
100-year proposed condition volume N/A above 100-year
SPF proposed condition volume 0.92 acre-feet
Required storage mitigation 100-year N/A above 100-year
Required storage mitigation SPF 1.74 acre-feet
If this area is developed after the new FEMA information is finalized no storage compensation will be
required since the area will be outside the 100-year floodplain.
We have been coordinating this information with all parties involved. Now that the information is
complete this project can be finalized.
Let me know if we can provide additional information.
Sincerely,
FREESE AND NICHOLS, INC.
Ronald W. Morrison, P.E., C.F.M.
Drainage Discipline Leader
xc: File
CC: Ken Griffen
OZ~E
ZONE X~
~ ~ Ro~,D ,R M591
ZONE
NAIlONAL FI.OOD INSURANCE PROGRAM
FIRM zone x :..:~{
nO0D mSu~.CE ~E MAP "" "~:~'
, , -.
DA~U~S CO~T~. ZONE X'
..
T[Z-J~ ,~ND ' ' ' ·
D~TCORPO~T]~D ~ QYZ
41171 '-
PMIEL 155 OF 725
X
=,t~_ ZONE X
,,~
~:ON~
MAP NUMBER i
48113C0155 l
EFF[CTIV[ DATE: !
PRELL'~[INAR~';; ZONE X
MICHAEL BAKER. JR~ IN(] -BEACOI~
JUL l 0 1999 { DRr,'[
ZONE X
RM198
/ ZONE
ZONE X ZONE X
CITY OF DALLAS
'AE 480171
/
BOULE%~RD
ZON
AE
ZONE X
ZONE
,
,,-
-'
' ~ ZO N E X ZO N E X ~ROLL ran
ZONE !
, ~NE X
NAilgNat FLOOR IIISIIIANC[
FIRM '
FLgO0 INSURANCE RATE MAID ZONE X pEEBLE /
alld ~ -
STREET INDEX
CITY OF
cOPPELk
TE×AS ~ t N E X
DALLAS AflD DEI~rON COUNT|F~
z.
ONLY PANEL PRINTED ":"
~ ',:',
/,,.,~
ZONE X ':"::,
.,',,
,,C,,.
COMMIIIIITY-P&IIEL IIIIII~IEII
MAP REVISED:
APRIL15,1994 ZONE X
·
,,
~NE X
FAIRWAY
BELTLINE
~LIMITS