Alexander Ct-SY 971113N ^C*I.
DOWDEY, ANDERSON AND ASSOCIATES, INC. [LE U TEW° (11F TQ,�4 RS U1�1 MAIL
CIVIL ENGINEERS
5225 VILLAGE CREEK DRIVE SUITE 200
PLANO, TEXAS 75093
(972) 931-0694 FAX (972) 931-9538
TO
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DATE + I JOS
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Proposed East Tract - Baptist Foundation Tract
Coppell, Texas
HYDRAULIC MODELING
August 31, 1995
Graham Associates
616 Six Flags Dr. #400
Arlington, Texas
�jO A Kl IT
A -[ ""Pe
�2 t N G►S
5 v A4 *l
100 YEAR
WATER SURFACES
SEC. NO No
Duplicate
Existing
Proposed
Effective
Natural
Floodway
Natural
Floodway
Natural
Floodway
Lower
27400
494.69
495.34
494.69
495.34
494.69
495.34
27540
494.67
495.57
494.67
495.57
496.67
495.57
27570
494.92
495.68
494.92
495,68
494.92
495.68
27620
495.61
495.72
495.61
495.72
495.61
495.72
1.0
496.24
496.57
496.24
496.57
496.24
496.57
2.0
496.46
496.80
496.46
496.80
496.46
496.80
2.5
496.61
496.97
496.61
496.97
496.61
496.97
3.0
497.62
497.82
497.62
497.82
497.58
497.82
3.3
499.01
499.14
499.01
499.14
499.01
499.14
3.6
499.36
499.57
499.36
499.57
499.35
499.57
4.0
499.91
500.17
499.91
500.17
499.91
500.12
4.5
501.31
501.57
501.31
501.57
501.27
501.45
Main
""0 4.50
501.31
501.57
501.31
501.57
501.27
501.45
01--3 5.00
501.54
501.90
501.54
501.90
501.51
501_.73
5.10
501.54
501.89
501.54
501.89
501.52
501.
+.�c 5.11
501.56
501.90
501.56
501.90
501.53
501.73
5.12
501.56
501.92
501.56
501.92
501.53
501.75
5.13
501.56
501.92
501.56
501.92
501.53
501.75
5.14
501.56
501.91
501.56
501.91
501.53
501.74
<o- 5.20
501.56
501.91
501.56
501.91
501.53
501.74
s-vi51 5.21
501.54
501.88
501.54
501.88
501.51
501.71
5.22
501.57
501.94
501.57
501.94
501.54
501.77
5.23
501.57
501.95
501.57
501.95
501.54
501.78
5.24
501.55
501.91
501.55
501.91
501.52
501.74
5.30
1501.45
501.78
501.45
501.78
501.42
501.78
x,05 6.00
500.93
501.53
500.93
501.53
501.01
501.40`
`037430130
503.72
503.66
503.72
503.66
503.72
503.59
Bypass
SJR � 4.5
501.31
501.57
501.31
501.57
501.27
501.45
70
501.31
501.49
501.31
501.49
501.13
501.22
76
,
501.29
501.61
501.27-
501.50
80
501.33
501.70
501.34
501.70
501.32
501.56
90
501.57
501.94
501.58
501.93
501.56
501.87
110 8;
501.87
502.28
501.88
502.28
501.91-
502.23'
Svl.ob 6.0 500
500.93
501.53
500.94
501.53
501.00
501.42-
So3,-1430130 Sbrt,'73
503.72
503.66
503.72
503.66
503.72
503.59
Upper
30130
503.72
503.67
503.72
503.66
503.72
503.59
30189
503.58
503.65
503.58
503.64
503.57
503.58
30190
503.45
503.53
503.45
503.52
503.44
503.45
30200
503.69
503.75
503.69
503.75
503.68
503.68
30201
504.09
504.15
504.09
504.14
504.08
504.09
30250
504.99
504.95
504.99
504.94
504.98
504.89
31310
506.56
506.83
506.56
506.83
506.56
506.80
r
minsunily Milne: //'' / O
IloullingSource: Jc,g V b 1° � re- e- /c
PiojectnrmeilJcnlifier: G O e V .40 -�,QfT
-I 111 177 -
II .►; 19 1993
Water Surface" Wit Che-CIt
effoctiv•
duplicate- 'off ective
revised existing
proposed
hv ;►t orn 1-1-99fiq
CFF_Fi5_F1✓ b-/-93
RfV_`w3_[.owR
s-��93
S,? as Rev. eX
ti U Nl MtiF.1' YC"El" `
snNc'
MIID.
NCXBELI FCXSEL' SUNC' NIO. 1.
SECNO NCXBEL' FCXSt .` SUNG'
It11D. 4
SECNU NCw8e1.'
i'CwSE1.`
SUM'.' wID. 4
X7070 WPO y92,82
0,39
/,2 4/Q.y3
W2.92 0.39' /At/
?7Yo0 N9y.G`l ,3q
0,(0(
�f l S
�t94.(vq y9S3S D.�b y/�
27 0'19.4 S.3 0,65
y /5
f -
75y0 q,?4,G7 y9S57
o•q 1
373
Y9y.b7 �f9f57 0.4/ 373
275- M, (o g7157 .9'0
373
�-
17.570 y9y•91 49,�,69
0,77
37�
27570 k9y,9/ �f9S.&0.77 37 el
�75To 49 92 �f9 .b8 D.76
373
�-
!7670 y950 YK29
0,/2
yyIf
76 W540 #9S.7z 0./2 qqel7G
111.4-.61 q9S.72 0.1/
1/4(-
496.2 4% .57 0.32
/60
l'
9 A l 0.33
/ /
-
r
'�
—�
.6 q?(017 0.36
ef,6 1197,R2 0,00
/10
35
�--
F
`
—
--
.7�f 0.13
125
�r-7L O
/30
F-
Comments:
I_ 100 year Inaturall W;.Irr S'.0a r 1 lr. m.....
z l n,-ruarlunent mawwaylw.Ier Surface Elevation
3 Surorarge value 4-Floodw.F Width
I , G e.ftv\
Attached are exhibits and computer runs that support a LOMR application to update the
effective FIRM's floodplain and floodway limits in the reach of Grapevine Creek that
extends from Denton Tad Road to Bethel Road.
Graprevine Creek 900 -yr
Water Surface Elevations (ft)
River Sta.
Natural
Encroached
Q Total
cfs
HEC -2
Duplicate
Effective
HEC -RAS
Imported
HEC -RAS
Modified
HEC -2
Duplicate
Effective
HEC -RAS
Imported
HEC -RAS
Modified
22600
11800
479.02
479.02
479.02
479.80
479.80
479.80
24000
11800
482.23
483.06
25000
11800
482.88
483.73
25100
11800
483.26
484.06
25370
11800
486.74
486.89
484.51
487.52
487.52
485.06
25470
11800
1 487.25
487.54
485.66
488.18
488.32
486.04
25485
Denton Ta
25500
11800
488.08
488.43
485.81
488.72
489.00
486.19
25550
11800
488.72
488.47
485.44
488.95
485.85
25685
11900
485.51
485.92
25725
11900
485.97
486.31
25820
11900
486.95
487.15
26170
11900
487.02
487.34
26300
11900
487.29
487.6
26700
11900
488.05
488.27
26880
11900
491.22
491.33
489.77
489.16
491.81
489.82
27050
10500
490.14
490.33
27400
10500
494.03
494.10
492.83
491.83
494.52
1 492.83
27540
10500
494.23
494.37
492.16
494.57
494.91
492.16
27555
Bethel Road
27570
10500
494.43
494.68
493.54
495.00
495.13
493.54
27620
10500
494.65
494.70
494.36
495.14
494.90
494.37
27900
10500
496.58
496.59
30130
10500
i502.87
503.31
502.59
1 503.52
1 503.87
502.60
27400. Exhibit 4 is a floodplain work map that shows the location of these cross
sections, the effective FIRM, and the proposed 100 -yr floodplain and flood way
delineations.
Table 1
Grapevine Creek 100 -yr Discharges (cls)
River Station
Q
27620
10500
26880
11900
25550
11800
III. COMPUTER MODELS
Computer models, input and output are included in this report as attachments under
report Section VII. The description and file names are as follows:
1. HEC -2 Current Effective Multiple Profile Model........................GRAPE20.DAT
2. HEC -2 Current Effective Floodway Mode.................................GRAPE21.DAT
3. HEC -RAS Imported Multiple Profile Model...............................7026.PRJ-p01
4. HEC -RAS Imported Floodway Model......................................7026.PRJ-p05
5. HEC -RAS Revised Conditions Multiple Profile Model .................7026.PRJ-p03
6. HEC -RAS Revised Conditions Floodway Model ......................... 7026.PRJ-p06
IV. CONCLUSIONS
The results obtained by this study are in compliance with the current floodplain criteria
for the City of Coppell and FEMA as shown in the summary of results in Table 2. The
table shows that, with the Denton Tap bridge replacement and coding cross sections
with recent aerial topography, the flood profile is lowered from downstream of Denton
Tap Road to upstream of Bethel Road.
Tributa?w G-1 ---.
of'Grapevine Creek
SETHEL ROADIZ ZON
SOO
Grapevine
Creek
ZONE X
ST, LOUIS
T
ROAD
Req
APPROXIMATE SCALE IN FEET
'UOG 0 10CG
'
IIIIIIIIIIIIIII
llllllllWlU
I
NATIONAL FLOOD INSURANCE PROGRAM
I
FIRM
1
FLOOD INSURANCE RATE MAP
DALLAS COUNTY,
TEXAS AND
INCORPORATED AREAS
PANEL 155 OF 125
SEE MAP INDEX FOR PANELS NOT PRIM -EDI
BETHE
f), SCH
j;
'ron'AIN<.
w
,p
CCtOWNITV NiIAREfl PANEL SUFF7
U C7
�
y
q
C
COPPELL Ci+� Or egpt)J 0:56
,i4iNC FVINC C:LY OFF e8(iifio tt5r,
G
w
V;=,4EEK
DON
CR
� z
�
4R9nn
9
_ 99
ZONE AE
��
MAP NUMBER
48113CO155 1
482
EFFECTIVE DATE:
AUGUST 23, 2001
484
484
S
477
rt
+�
Federal Emergency Management Agency
FRPN�IS�
Sa,
This is an official copy of a portion of the above referenced flood
map. It
(I GLENDALE DRIVE
was extracted using F -MIT On -Line. This map does not reflect
changes
or amendments which may have been made subsequent to the
date on the
title block. For the latest product information about National Flood
Insurance
Program flood maps check the FEMA Flood Map Store at www.msc.fema.gov
rn
N
Table 4. Summary of Discharges (Cont'd)
Drainage Area Peak Discharges (Cubic Feet per Second)
Flooding Source and Location (Square Miles) 10 -Year 50 -Year 100 -Year 500 -Year
GLENN BRANCH
At confluence with Little Creek
Approximately 3,200 feet below Bear Creek Road
Approximately 3,000 feet below Bear Creek Road
At Bear Creek Road
GRAPEVINE CREEK
At mouth
At intersection with extension
of Cotton Road
At Radio Road
At State Route 114
HACKBERRY CREEK
At mouth
Above confluence of Cottonwood Branch
Below confluence of South Fork of
Hackberry Creek
Above confluence of South Fork of
Hackberry Creek
Below confluence of Mud Springs Creek
Above confluence of Mud Springs Creek
HALL BRANCH
At confluence with White Rock Creek
Above right bank tributary approximately
400 feet below Weber Road
At upstream limit of detailed study
2.02
3,050
4,200
4,700
5,900
1.67
2,800
3,850
4,300
5,400
1.18
1,900
2,650
2,950
3,700
1.06
1,900
2,650
2,950
3,700
11.48
5,900
8,600
9,700
12,700
5.95
7,300
10,000
11,200
14,200
3.68
5,100
7,000
7,900
9,900
2.77
4,900
6,700
7,500
9,400
21.22
13,300
18,900
21,400
27,700
15.13
9,400
13,400
15,200
19,600
13.66
11,000
15,400
17,300
22,100
10.44
8,200
13,200
14,900
18,900
5.45
8,000
11,000
12,300
15,500
1.76
3,050
4,150
4,600
5,800
2.16
3,150
4,350
4,850
3,650
1.44
2,050
2,700
3,000
3,650
0.39
850
1,100
1,250
1,500
0_0
BASE FLOOD
FLOODING SOURCE
FLOODWAY
WATER -SURFACE ELEVATION
WITHOUT WITH
I
CROSS SECTION
DISTANCE
WIDTH
SECTION AREA
MEAN VELOCITY
REGULATORY FLOODWAY FLOODWAY INCREASE
(FEET)
(SQUARE FEET)
(FEET PER
SECOND)
(FEET NGVD)
Glenn Branch
A
680'
64
576
8.2
636.8
636.8
637.8 1.0
B
1,940'
58
531
8.1
644.4
644.4
645.2 0.8
C
2,750'
55
343
8.6
650.4
650.4
651.2 0.8
D
3,670'
69
464
6.4
658.7
658.7
659.6 0.9
E
5,100'
130
479
6.2
688.9
688.9
689.9 1.0
Grapevine
Creek
A
8,5002
300
1,778
5.5
439.6
438.5'
438.5' 0.0
B
12,9002
940
3,141
3.1
448.0
448.0
448.5 0.5
C
14,1702
470
2,079
5.3
453.0
453.0
453.8 0.8
D
16,5432
638
4,624
2.4
461.5
461.5
462.3 0.8
E
20,700'
370
3,063
3.9
471.5
471.5
472.3 0.8
F
22,7002
200
1,566
7.5
478.0
478.0
478.4 0.4
G
24,000'
349
2,498
4.7
482.5
482.5
482.9 0.4
44-
26,9212
145
1,510
7.9
491.2
491.2
491.8 0.6
1
32,1802
119
1,301
8.1
506.7
506.7
507.1 0.4
Tributary G-1
of Grapevine
Creek
A
9454
137
777
4.0
493.7
493.7
493.7 0.0
B
3,1254
82
432
7.3
499.5
499.5
499.7 0.2
'Feet above mouth 'Feet above confluence with Elm Fork Trinity River 'Elevation computed without consideration of flooding from Elm Fork Trinity River 4 Feet above confluence with Grapevine Creek
T
A
FEDERAL EMERGENCY MANAGEMENT AGENCY
FLOODWAY DATA
B
L
DALLAS COUNTY, TX
GLENN BRANCH - GRAPEVINE CREEK
E
AND INCORPORATED AREAS
TRIBUTARY G-1 OF GRAPEVINE CREEK
$oil!