Preliminary Drainage Study
Page 1 of 2
XO MARRIAGE TODAY – PRELIMINARY DRAINAGE STUDY
CITY OF SOUTHLAKE, TARRANT COUNTY, TEXAS
APRIL 26, 2021
Prepared for:
Department of Planning & Development Services
City of Southlake
1400 Main Street, Suite 310
Southlake, Texas 76092
Prepared by:
Parkhill
255 N. Center Street
Suite 200
Arlington, Texas 76011
817.649.3216
Page 2 of 2
1.0 INTRODUCTION
XO Marriage Today is a proposed office building located on a 5.0-acre site along Kirkwood Boulevard
and Grace Lane. The purpose of this report is to analyze any drainage impacts that changing the use for
this property would have on-site or adjacent properties.
2.0 HYDROLOGY
Parkhill has completed a drainage analysis for the existing and developed site to determine the
additional runoff produced by the proposed improvements. The rational method was used to compute
the total runoff values. Runoff coefficients and intensities are based on the 2020 iSWM Hydrology
Technical Manual and a minimum time of concentration of 10 minutes was used for the developed
condition.
EXISTING CONDITIONS HYDROLOGY
The site currently holds detention from a neighboring site, The Westin Hotel, in a detention channel that
drains to a culvert under Kirkwood Boulevard. See the attached ‘Detention Plan’ (Table 2, Step 1) for
pre-development 100-year runoff values for the XO Marriage Today site and Westin Hotel site.
PROPOSED CONDITIONS HYDROLOGY
See attached ‘Drainage Area Map’ (Table 1) for proposed hydrology calculations for the site. The
hydrology calculations shown account for the ultimate development of this site. The runoff that exceeds
pre-development flow will be detained on-site to prevent overloading the downstream drainage system.
See attached ‘Detention Plan’ for post-development 100-year runoff values (Table 2, Step 2) for the XO
Marriage Today site and required detention volume (Table 2, Step 3).
6206
2
0
620
625
6
3
0
6
3
0
630
635
635
635
6
3
5
6
3
5
635
635
6
4
0
640
640
6
4
0
6
4
0
640
640
645645
6
4
5
645 645
62162
2
623624
626627
62
8
6
2
8
628
6
2
9
6
2
9
629
6
3
1
6
3
1
631
632
632
6
3
2
6
3
2
632
633
633
6
3
3
6
3
3
633
633
633
634
634
634
634
6
3
4
63
4
634
636
636
6
3
6
6
3
6
636
636
636637
637
6
3
7
637
637
6
3
7
63
7
6
3
8
638
638
6
3
8
6
3
8
638
638
639
6
3
9
639
639
6
3
9
6
3
9
639
641
641
641
64
1
6
4
1
641
6
4
1
642
642
6
4
2
6
4
2
642
643
643
6
4
3
643
643
6
4
3
643
644
644
644 644
6
4
4
6
4
6
646
64
6
6
4
7
647
647648649 640
64
5
645 637638639641
64
2
642
64
3
643
64
4
644
64
6
6
4
6
64
5
640 635
645
6
3
5
6
3
0
F
I
N
I
S
H
E
D
F
L
O
O
R
E
L
E
V
A
T
I
O
N
6
4
6
.
5
0
6
4
0
6
3
5
6
3
0
6
3
0
6
3
5
6
4
0
6
3
5
6
3
5
6
4
0
6
4
0
6
4
5
6
4
5
6
4
5
LP
LP
LP
LP
LPLP LPLP LP LPLP
LP
LP
LP
LP
LP
LP
X
ICVICVICVICV
ICV
ICV
ICV
ICV
ICV
ICV
WV
WV
WV
WV
SSMH
SDMH
SDMHSDMH
SDMH
WMFH
FH
W
W
W
W
S
S
S
S
S
S
S
S
W
W
W
W
W
W
W
W
W
W
WWWW
N
A-10.17 ac
G
R
A
C
E
L
A
N
E
KIRKWOOD BOULEVARD
A
-
4
0
.
9
7
a
c
A
-
3
0
.
1
3
a
c
A
-
2
0
.
1
6
a
c
B
-
1
0
.
2
5
a
c
B
-
2
0
.
1
1
a
c
B
-
3
0
.
4
3
a
c
C
-
1
0
.
3
7
a
c
C
-
2
0
.
6
7
a
c
D
-
1
2
.
8
0
a
c
D-21.66 acPROPERTY LINE
P
R
O
P
E
R
T
Y
L
I
N
E
FILE NAME: X:\2019\8555.19\03_DSGN\01_DWG\050_CIVIL\C-100 DRAINAGE AREA MAP.dwg LAYOUT NAME: C100 PRINTED: Wednesday, April 21, 2021 - 6:28pm USER: CHadsall
P
a
r
k
h
i
l
l
.
c
o
m
P
R
O
J
E
C
T
N
O
.
C
L
I
E
N
T
#
D
A
T
E
D
E
S
C
R
I
P
T
I
O
N
K
E
Y
P
L
A
N
1
5
4
3
21 A B C D 2
3
4
5
XO MARRIAGE CENTER
X
O
M
A
R
R
I
A
G
E
S
O
U
T
H
L
A
K
E
,
T
X
7
6
0
9
2
8
5
5
5
.
1
9
-
0
3
/
1
9
/
2
0
2
1
5
0
%
C
D
P
A
C
K
A
G
E
T
H
I
S
D
O
C
U
M
E
N
T
I
S
R
E
L
E
A
S
E
D
O
N
A
P
R
.
2
6
,
2
0
2
1
F
O
R
T
H
E
P
U
R
P
O
S
E
O
F
I
N
T
E
R
I
M
R
E
V
I
E
W
U
N
D
E
R
T
H
E
A
U
T
H
O
R
I
T
Y
O
F
L
A
R
R
Y
D
.
S
T
O
N
E
,
P
.
E
.
,
T
E
X
A
S
L
I
C
E
N
S
E
#
4
2
2
5
2
.
I
T
I
S
N
O
T
T
O
B
E
U
S
E
D
F
O
R
R
E
G
U
L
A
T
O
R
Y
A
P
P
R
O
V
A
L
,
C
O
N
S
T
R
U
C
T
I
O
N
,
B
I
D
D
I
N
G
O
R
P
E
R
M
I
T
P
U
R
P
O
S
E
S
.
P
A
R
K
H
I
L
L
S
M
I
T
H
&
C
O
O
P
E
R
,
I
N
C
.
F
-
5
6
0
D
r
a
i
n
a
g
e
A
r
e
a
M
a
p
C
-
1
0
0
4
0
'
8
0
'
0
iSWM Hydrology Calculations - Marriage Today SouthlakeD.A.Areacc25c100tcI5I25I100Q5Q25Q100No.ac.(includes cf)minin/hrin/hrin/hrcfscfscfsA-10.170.951.001.00105.5147.7829.7620.891.321.66A-20.160.350.390.44105.5147.7829.7620.310.480.68A-30.130.951.001.00105.5147.7829.7620.681.011.27A-40.970.700.770.88105.5147.7829.7623.745.818.29B-10.250.350.390.44105.5147.7829.7620.480.751.07B-20.110.951.001.00105.5147.7829.7620.580.861.07B-30.430.800.881.00105.5147.7829.7621.902.944.20C-10.370.800.881.00105.5147.7829.7621.632.533.61C-20.670.800.881.00105.5147.7829.7622.964.596.54D-12.800.350.390.44105.5147.7829.7625.408.3911.96D-21.660.350.390.44105.5147.7829.7623.204.977.09SITE TOTAL7.7221.7733.6647.44Notes:1) A minimum time of concentration of tc= 10 min was used2) Intensities from Tarrant County Rainfall Data - 2020 iSWM Hydrology Technical Manual
625
630630
630
635
635
635
635
6
3
5
635635640
640
640
6
4
0
640
645645
645
6
4
5
645
626627
628628
628
629629
629
631 631
631
632
632
632
6
3
2
632
633
633
633
6
3
3
633
633 633
634
634
634
634 634
63
4
634
636
636
636
6
3
6
636
636
636637
637
637
637
637
6
3
7
637638
638
638
6
3
8
638638
638
639 639
639
639
6
3
9
639
639
641
641
641
641
642
642
642
643
643
643 643
644
644
644 644
6
4
6
646646647647640
64
5
645 637638639641
64
2
642
64
3
643
64
4
644
64
6
646
LP
LP
LP
LP
LP LPLPLPLP LP LP LPLP LP
LP
ICV
ICV
ICV
ICV
WV WV
SDMHSDMH
WMFHFH
FH
W
W
W
W
W
W
W W WWWWGRACE LANE KIRKWOOD BOULEVARD645640635
645
635 630
6
4
0
6
3
5
6
3
0
6
3
0
6
3
5
6
4
0
6
3
5
6
3
5
6
4
0
6
4
0
6
4
5
6
4
5
6
4
5
D
E
T
E
N
T
I
O
N
C
H
A
N
N
E
L
V
=
1
1
8
,
4
0
0
C
F
(
W
I
T
H
1
'
F
R
E
E
B
O
A
R
D
)
PROPERTY LINE
P
R
O
P
E
R
T
Y
L
I
N
E
FILE NAME: X:\2019\8555.19\03_DSGN\01_DWG\050_CIVIL\C-101 DETENTION PLAN.dwg LAYOUT NAME: C-101 PRINTED: Wednesday, April 21, 2021 - 6:42pm USER: CHadsall
P
a
r
k
h
i
l
l
.
c
o
m
P
R
O
J
E
C
T
N
O
.
C
L
I
E
N
T
#
D
A
T
E
D
E
S
C
R
I
P
T
I
O
N
K
E
Y
P
L
A
N
1
5
4
3
21 A B C D 2
3
4
5
XO MARRIAGE CENTER
X
O
M
A
R
R
I
A
G
E
S
O
U
T
H
L
A
K
E
,
T
X
7
6
0
9
2
8
5
5
5
.
1
9
-
0
3
/
1
9
/
2
0
2
1
5
0
%
C
D
P
A
C
K
A
G
E
T
H
I
S
D
O
C
U
M
E
N
T
I
S
R
E
L
E
A
S
E
D
O
N
A
P
R
.
2
6
,
2
0
2
1
F
O
R
T
H
E
P
U
R
P
O
S
E
O
F
I
N
T
E
R
I
M
R
E
V
I
E
W
U
N
D
E
R
T
H
E
A
U
T
H
O
R
I
T
Y
O
F
L
A
R
R
Y
D
.
S
T
O
N
E
,
P
.
E
.
,
T
E
X
A
S
L
I
C
E
N
S
E
#
4
2
2
5
2
.
I
T
I
S
N
O
T
T
O
B
E
U
S
E
D
F
O
R
R
E
G
U
L
A
T
O
R
Y
A
P
P
R
O
V
A
L
,
C
O
N
S
T
R
U
C
T
I
O
N
,
B
I
D
D
I
N
G
O
R
P
E
R
M
I
T
P
U
R
P
O
S
E
S
.
P
A
R
K
H
I
L
L
S
M
I
T
H
&
C
O
O
P
E
R
,
I
N
C
.
F
-
5
6
0
N
D
e
t
e
n
t
i
o
n
P
l
a
n
C
-
1
0
1
4
0
'
8
0
'
0
M
o
d
i
f
i
e
d
R
a
t
i
o
n
a
l
M
e
t
h
o
d
D
e
t
e
n
t
i
o
n
P
o
n
d
D
e
s
i
g
n
-
M
a
r
r
i
a
g
e
T
o
d
a
y
S
o
u
t
h
l
a
k
e
(
S
i
t
e
O
n
l
y
)
S
t
e
p
D
r
a
i
n
a
g
e
A
r
e
a
T
c
(
m
i
n
)
I
1
0
0
(
i
n
/
h
r
)
C
A
(
a
c
r
e
)
Q
1
0
0
(
c
f
s
)
S
u
b
t
o
t
a
l
Q
1
0
0
(
c
f
s
)
T
o
t
a
l
1
P
r
e
-
D
e
v
e
l
o
p
m
e
n
t
A
L
L
1
5
8
.
0
2
0
.
3
0
7
.
7
2
1
8
.
5
7
1
8
.
5
7
2
P
o
s
t
-
D
e
v
e
l
o
p
m
e
n
t
A
-
1
1
0
9
.
7
6
1
.
0
0
0
.
1
7
1
.
6
6
4
7
.
4
4
A
-
2
1
0
9
.
7
6
0
.
4
4
0
.
1
6
0
.
6
9
A
-
3
1
0
9
.
7
6
1
.
0
0
0
.
1
3
1
.
2
7
A
-
4
1
0
9
.
7
6
0
.
8
8
0
.
9
7
8
.
2
9
B
-
1
1
0
9
.
7
6
0
.
4
4
0
.
2
5
1
.
0
7
B
-
2
1
0
9
.
7
6
1
.
0
0
0
.
1
1
1
.
0
7
B
-
3
1
0
9
.
7
6
1
.
0
0
0
.
4
3
4
.
2
0
C
-
1
1
0
9
.
7
6
1
.
0
0
0
.
3
7
3
.
6
1
C
-
2
1
0
9
.
7
6
1
.
0
0
0
.
6
7
6
.
5
4
D
-
1
1
0
9
.
7
6
0
.
4
4
2
.
8
0
1
1
.
9
6
D
-
2
1
0
9
.
7
6
0
.
4
4
1
.
6
6
7
.
0
9
3
T
d
(
m
i
n
)
C
w
I
(
i
n
/
h
r
)
A
(
a
c
r
e
)
Q
a
(
c
f
s
)
V
p
r
e
l
i
m
(
f
t
3
)
P
1
8
0
P
t
d
V
r
e
q
(
f
t
3
)
V
r
e
q
(
a
c
r
e
-
f
t
)
3
9
.
7
6
0
.
6
3
9
.
7
6
7
.
7
2
1
8
.
5
7
3
0
,
5
4
0
5
.
3
6
3
.
0
3
5
4
,
0
3
4
1
.
2
4
M
o
d
i
f
i
e
d
R
a
t
i
o
n
a
l
M
e
t
h
o
d
D
e
t
e
n
t
i
o
n
P
o
n
d
D
e
s
i
g
n
-
M
a
r
r
i
a
g
e
T
o
d
a
y
S
o
u
t
h
l
a
k
e
(
S
i
t
e
&
H
o
t
e
l
S
i
t
e
)
S
t
e
p
D
r
a
i
n
a
g
e
A
r
e
a
T
c
(
m
i
n
)
I
1
0
0
(
i
n
/
h
r
)
C
A
(
a
c
r
e
)
Q
1
0
0
(
c
f
s
)
S
u
b
t
o
t
a
l
Q
1
0
0
(
c
f
s
)
T
o
t
a
l
1
P
r
e
-
D
e
v
e
l
o
p
m
e
n
t
-
S
I
T
E
A
L
L
1
5
8
.
0
2
0
.
3
0
7
.
7
2
1
8
.
5
7
6
1
.
4
5
P
r
e
-
D
e
v
e
l
o
p
m
e
n
t
-
H
O
T
E
L
F
L
O
W
V
A
L
U
E
F
R
O
M
2
0
1
7
W
E
S
T
I
N
C
I
V
I
L
P
L
A
N
S
4
2
.
8
8
2
P
o
s
t
-
D
e
v
e
l
o
p
m
e
n
t
-
S
I
T
E
A
-
1
1
0
9
.
7
6
1
.
0
0
0
.
1
7
1
.
6
6
1
2
1
.
5
2
A
-
2
1
0
9
.
7
6
0
.
4
4
0
.
1
6
0
.
6
9
A
-
3
1
0
9
.
7
6
1
.
0
0
0
.
1
3
1
.
2
7
A
-
4
1
0
9
.
7
6
0
.
8
8
0
.
9
7
8
.
2
9
B
-
1
1
0
9
.
7
6
0
.
4
4
0
.
2
5
1
.
0
7
B
-
2
1
0
9
.
7
6
1
.
0
0
0
.
1
1
1
.
0
7
B
-
3
1
0
9
.
7
6
1
.
0
0
0
.
4
3
4
.
2
0
C
-
1
1
0
9
.
7
6
1
.
0
0
0
.
3
7
3
.
6
1
C
-
2
1
0
9
.
7
6
1
.
0
0
0
.
6
7
6
.
5
4
D
-
1
1
0
9
.
7
6
0
.
4
4
2
.
8
0
1
1
.
9
6
D
-
2
1
0
9
.
7
6
0
.
4
4
1
.
6
6
7
.
0
9
P
o
s
t
-
D
e
v
e
l
o
p
m
e
n
t
-
H
O
T
E
L
F
L
O
W
V
A
L
U
E
F
R
O
M
2
0
1
7
W
E
S
T
I
N
C
I
V
I
L
P
L
A
N
S
7
4
.
0
8
3
T
d
(
m
i
n
)
C
w
I
(
i
n
/
h
r
)
A
(
a
c
r
e
)
Q
a
(
c
f
s
)
V
p
r
e
l
i
m
(
f
t
3
)
P
1
8
0
P
t
d
V
r
e
q
(
f
t
3
)
V
r
e
q
(
a
c
r
e
-
f
t
)
3
1
.
8
8
0
.
6
8
9
.
7
6
1
8
.
2
1
6
1
.
4
5
5
8
,
3
7
5
5
.
3
6
2
.
8
1
1
1
1
,
3
4
8
2
.
5
6