HomeMy WebLinkAboutDrainage ReportDrainage Report
WEST POINTE BUILDING CENTER
ROCK PRAIRIE WEST
LOT 9, BLOCK 1
FEBRUARY 2003
Prepared By:
Rogers Engineering Services
1712 Southwest Parkway, Suite 105
College Station, Texas 77842
(979) 680-8840
CERTIFICATION
I, Alton G. Rogers, Registered Professional Engineer No.50833, State of Texas, certify that
this report for the drainage design for the West Pointe Building Center, Rock Prairie West, Lot 9,
Block 1, was prepared by me in accordance with the provisions of the City of College Station
Drainage Policy and Design Standards for the owners thereof.
ALTON G. ROGERS
...................
Drainage Report
Rock Prairie West, Lot 9 Block 1
WM.50833
Table of Contents
West Pointe Building Center
Rock Prairie West, Lot 9, Block 1
Proposed Retail and Warehouse
Introduction: ........... ....................... 1
General Location and Description ................................................. 1
Primary Drainage Basin Description ............................................... 1
Drainage Design Criteria........................................................2
Drainage Facility Design........................................................ 2
Conclusion................................ 3
Exhibits
FEMA Flood Insurance Rate Map Excerpt
Drainage Area Map - Existing Condition
Drainage Area Map - Proposed Condition
Drainage Area Calculations
Routing Hydrographs
Drainage Report
Rock Prairie West, Lot 9 Block 1
"B-2"
« C',
"D"
ii
Storm Drainage Report
West Pointe Building Center
Rock Prairie West, Lot 9, Block 1
Proposed Retail and Warehouse
Introduction:
This storm drainage report is intended to cover the necessary drainage infrastructure for the
proposed development site improvements. The parameters used for design and the existing
conditions of the on -site area are incorporated to show how the final drainage design will accomplish
the desired drainage objectives per the City of College Station Drainage Policy and Design
Standards. (DPDS)
General Location and Description:
The proposed building is located in the southern portion of College Station. The project site
contains one commercial lot located along Old Wellborn Road between Gandy Road and North
Graham Road. The lot is platted as Lot 9, Block 1 Rock Prairie West, and is zoned A-O. The 2.4
acre site is undeveloped cattle pasture and is gently sloping with an average of 1.67% slopes.
The current land cover is considered natural grassland, and the proposed site will contain
both landscaped areas and impervious areas. The proposed site is owned by Mr. Charles Moreau,
of College Station.
Primary Drainage Basin Description:
The current site drains from the northern comer to the southern comer of Lot 9, Block 1 Rock
Prairie West. Storm water that drains to the southeast eventually flows into the South Fork of Lick
Creek. The developed site drains to the south corner of Lot 9.
No portion of the site is within the 500 year flood plain per the Federal Emergency
Management Agency Flood Insurance Rate Map Panel 48041 COI 82C.P. for Brazos County, Texas
Drainage Report
Rock Prairie West, Lot 9 Block 1 1
and Incorporated Areas effective July 2, 1992 (see Exhibit "A").
Drainage Design Criteria:
All drainage design is in accordance with the City DSPS. The design rainstorm is the 10 year
storm event. Flow calculations for all drainage areas are based on the Modified Rational Method.
Storm recurrence intervals used were the 5, 10, 25, 50, 100 year interval storm event.
The storage volume required for the detention facility is based on calculations outlined in the
City DSPS method of subtracting pre- and post -development hydrographs and peak flows computed
using the Rational Method for a ten (10) year design storm event. The site requires 0.21 ac-ft of
storm water storage.
Drainage Facility Design:
The site will be served by a detention facility located along the rear property line. The pond
will consist of an earthen berm with a low flow channel. Exhibit "B" shows the proposed drainage
areas for the pond. The four (4) drainage areas shown were routed simultaneously through the
detention facility. All impervious area created by the buildings and parking lot will be captured and
routed to the detention facility. The study point for the project is the outfall device of the proposed
detention facility. The outlet device for the pond is a 18" RCP outlet pipe with headwalls and energy
dissipaters. The pond basin elevation is set at 321.00'. The top of the berm elevation is 322.00'. The
pond has a storage capacity of 0.22 ac-ft.
Drainage Report
Rock Prairie West, Lot 9 Block 1 2
The following summary table shows the peak flow for the Pre -development events and the peak
flows for the Post -development events.
Study Point - Pond Outfall
Pre -development
Pond In
Pond Out
Q5
3.95 cfs
13.29 cfs
1.93 cfs
Q10
4.47 cfs
14.92 cfs
4.03 cfs
Q25
5.13 cfs
17.04 cfs
6.31 cfs
Q51
5.82 cfs
19.26 cfs
8.06 cfs
Q,00
6.07 cfs
20.11 efs
8.06 cfs
Conclusion:
The Post -development peak discharge does not exceed the Pre -development peak discharge
for the 5, 10, 25, 50, or 100 year event. In all cases, including the 100 year event, storm water is
released into the natural outfall. The drainage design for this site meets the requirements as stated
in the City of College Station Drainage Policy and Design Standards.
Drainage Report
Rock Prairie West, Lot 9 Block 1
E
�
o
m
a
C
<
ME
E ,y E
Cd
�
oos��
_�=
ZE
y e
W
G C'O
o
Q
0Ccd
`e
mo8$
f
N
V QO ex
`sit
Nana z
q
CACO
Q>C� �F
a
'_{
2
EFc�€"
mF.z..-. a
E�:
-4e'
8
amm2i
aou
m
o
SOr2t
m
c
o:?
f E•
eat 8
Om�LLO
smE -F
one
�3`mcn
PO
0
,P
QP
P�
P�
5p
X
4 d
t
a
N
/
N
Exhibit B
Exhibit C
OOND
w
U
00H
C
090
m
U
091
G
9ZD
N
U
9Z1
C
OM
j
on
c
90
2 i
U
sl
1
L I
= 1
c
ofasn
i
c
�E
of -oleo
i
c.
4.oalOA
ped Mold pueNanO
6ua-I mold puepanp
Cc
r=
VU mol
cr
c
O 'luawaned
O? c
0
earl padowepun
cl
O c
eajv le;o
v
Q
ealV 96euleja
c
L
6
zu
D 7
� coi
r rn
A N
h M
V �
O
N
[�IMMIM
W U
LDQ
Q
� CU
~ O
II
w L1J
C2 J
w w
ry >
0i
z
w
Q
a
ry
Q
z
w
z
w
0
J
W
>
w
Q
LJ
n
z
0
LD
z
z
H
W
W
(S-JS) 0 '3DNVH3SIQ
Drainage Report
WEST POINTE BUILDING CENTER
ROCK PRAIRIE WEST
LOT 9, BLOCK 1
FEBRUARY 2003
Prepared By:
Rogers Engineering Services
1712 Southwest Parkway, Suite 105
College Station, Texas 77842
(979) 680-8840
CERTIFICATION
I, Alton G. Rogers, Registered Professional Engineer No.50833, State of Texas, certify that
this report for the drainage design for the West Pointe Building Center, Rock Prairie West, Lot 9,
Block 1, was prepared by me in accordance with the provisions of the City of College Station
Drainage Policy and Design Standards for the owners thereof.
k •�� >A
�1
ALTON G. ROGERS
................
0 50833 r'R
Drainage Report
Rock Prairie West, Lot 9 Block 1
Z
Alto Rogers P.E. No. 50833
Table of Contents
West Pointe Building Center
Rock Prairie West, Lot 9, Block 1
Proposed Retail and Warehouse
Introduction: 1
General Location and Description ................................................. 1
Primary Drainage Basin Description ............................................... 1
Drainage Design Criteria........................................................2
Drainage Facility Design........................................................ 2
Conclusion...................................................................3
Exhibits
FEMA Flood Insurance Rate Map Excerpt
Drainage Area Map - Existing Condition
Drainage Area Map - Proposed Condition `B-2"
Drainage Area Calculations "C"
Routing Hydrographs "D"
Drainage Report
Rock Prairie West, Lot 9 Block 1 ii
Storm Drainage Report
West Pointe Building Center
Rock Prairie West, Lot 9, Block 1
Proposed Retail and Warehouse
Introduction:
This storm drainage report is intended to cover the necessary drainage infrastructure for the
proposed development site improvements. The parameters used for design and the existing
conditions ofthe on -site area are incorporated to show how the final drainage design will accomplish
the desired drainage objectives per the City of College Station Drainage Policy and Design
Standards. (DPDS)
General Location and Description:
The proposed building is located in the southern portion of College Station. The project site
contains one commercial lot located along Old Wellborn Road between Gandy Road and North
Graham Road. The lot is platted as Lot 9, Block 1 Rock Prairie West, and is zoned A-O. The 2.4
acre site is undeveloped cattle pasture and is gently sloping with an average of 1.67% slopes.
The current land cover is considered natural grassland, and the proposed site will contain
both landscaped areas and impervious areas. The proposed site is owned by Mr. Charles Moreau,
of College Station.
Primary Drainage Basin Description:
The current site drains from the northern corner to the southern corner ofLot 9, Block 1 Rock
Prairie West. Storm water that drains to the southeast eventually flows into the South Fork of Lick
Creek. The developed site drains to the south corner of Lot 9.
No portion of the site is within the 500 year flood plain per the Federal Emergency
Management Agency Flood Insurance Rate Map Panel 48041 C0182C.P. for Brazos County, Texas
Drainage Report
Rock Prairie West, Lot 9 Block 1 1
and Incorporated Areas effective July 2, 1992 (see Exhibit "A').
Drainage Design Criteria:
All drainage design is in accordance with the City DSPS. The design rainstorm is the 10 year
storm event. Flow calculations for all drainage areas are based on the Modified Rational Method.
Storm recurrence intervals used were the 5, 10, 25, 50, 100 year interval storm event.
The storage volume required for the detention facility is based on calculations outlined in the
City DSPS method of subtracting pre- and post -development hydrographs and peak flows computed
using the Rational Method for a ten (10) year design storm event. The site requires 0.21 ac-ft of
storm water storage.
Drainage Facility Design:
The site will be served by a detention facility located along the rear property line. The pond
will consist of an earthen berm with a low flow channel. Exhibit "B" shows the proposed drainage
areas for the pond. The four (4) drainage areas shown were routed simultaneously through the
detention facility. All impervious area created by the buildings and parking lot will be captured and
routed to the detention facility. The study point for the project is the outfall device of the proposed
detention facility. The outlet device for the pond is a 18" RCP outlet pipe with headwalls and energy
dissipaters. The pond basin elevation is set at 321.00'. The top of the berm elevation is 322.00'. The
pond has a storage capacity of 0.22 ac-ft.
Drainage Report
Rock Prairie West, Lot 9 Block 1
The following summary table shows the peak flow for the Pre -development events and the peak
flows for the Post -development events.
Point - Pond Outfall
Pre -development
Pond hi
Pond Out
Q5
3.95 efs
13.29 cfs
1.93 cfs
Q10
4.47 cfs
14.92 cfs
4.03 cfs
Q25
5.13 cfs
17.04 cfs
6.31 cfs
Qso
5.82 cfs
19.26 cfs
8.06 cfs
Q100
6.07 cfs
20.11 cfs
8.06 cfs
Conclusion:
The Post -development peak discharge does not exceed the Pre -development peak discharge
for the 5, 10, 25, 50, or 100 year event. In all cases, including the 100 year event, storm water is
released into the natural outfall. The drainage design for this site meets the requirements as stated
in the City of College Station Drainage Policy and Design Standards.
Drainage Report
Rock Prairie West, Lot 9 Block 1
E
om
v.
ym m_'co
yy
o Q Q j�i t�ia� Qm cq
Ny
C
ad
�V W
y
ME oio
W
a
1
0=w0
'c
R
Op
i
z
Z
CD
o
e
<
HBO -
'<
W
N
=
UQ�
CD
A
e
��
Q'i��
Our
tt09t
S
goLo..
®
c u$
_
Iff
3 �E
og OLL9
c maYE
c$
=mE3m
ego
PO
0
QP
P�
P�
-X
SODS
J
t
a
IY
/
Exhibit B
Exhibit C
OOLU
fA
U
OM
I
2
C
090
w
U
091
2
c
9zo
9Z1
2
c
Mo
U
ml
2 �
c�
90
i
1
N 1
U
9I
�
I
)
i
i I
=
i
t
C
of asn
C
of oleo
�
C
C �
A4POIOA
cc
C
F
Iled Mold PuepaAO
Ua1 MOIL pUepaA0
c
r
vo 18101
cc
C
O'luawaned
o C
O
eajy padowepun
c!
o c
eajy lelol
ci c
Q
earl 06eweia
C
c
u
O ._
Z LL
n Cn
n N
0ZY,
� N
n �
! t`
v �
Exhibit D
z
0
I—
W
W U
LDQ
Q
(U
~ o
Oj
ti
W
W
EJ
I
W
l�
Q
ry
H—
LD
z
z
H
n/
W
W
(S-�S) C `3�)NVH3SIQ