HomeMy WebLinkAboutDrainage ReportDrainage Report
for
College Main Lofts
College Station, Texas
March 2012
Developer:
Worth Acquisitions, Inc
4400 Old College Road
Bryan, Texas77801
(979)314-9070
Prepared By:
41LI61tz Engineering, LLC
TBPE Firm No. 12327
P.O. Box 11995
College Station, TX 77842
2730 Longmire Drive, Suite A
College Station, Texas 77845
(979)764-3900
Drainage Report
College Main Lofts
College Station, Texas
March 7, 2012
ENGINEER
Schultz Engineering, LLC
P.O. Box 11995
College Station, Texas 77842
Phone: (979) 764 — 3900
Worth Acquisitions, Inc.
4400 Old College Road
Bryan, Texas 77801
(979)314-9070
GENERAL DESCRIPTION AND LOCATION
This project consists of the development of two vacant lots on College Main in College Station, Texas.
The development consists of two multi -family buildings, which will include the construction of sitework,
utilities and other infrastructure.
The development includes Block 4, Lot 5 and Block 5, Lot 9 W.C. Boyett Estate Partition on College Main.
The project lots are located at 403 and 408 College Main, which is approximately 50 feet northwest of
Louise Ave on either side of College Main.
403 College Main
Area: 0.17 acres
Existing Land Use: Vacant
Proposed Land Use: Multi -Family
Number of Lots: 1
Drainage Basin: Burton Creek Watershed
FEMA FIRM: #48041C0143 — C, Dated July 2, 1992
Floodplain: None of the development lies within the floodplain.
408 College Main
Area: 0.14 acres
Existing Land Use: Vacant
Proposed Land Use: Multi -Family
Number of Lots: 1
Drainage Basin: Burton Creek Watershed
FEMA FIRM: #48041C0143 — C, Dated July 2, 1992
Floodplain: None of the development lies within the floodplain.
HYDROLOGIC CHARACTERISTICS
The pre -development condition of the land is grassy vacant lot. Exhibit A shows the pre -development and
post development drainage areas and the runoff flow direction.
Page 1 of 3
Drainage Report
College Main Lofts
College Station, Texas
March 7, 2012
GENERAL STORMWATER PLAN
The drainage plan for each lot in the development will involve the installation of an onsite private storm
sewer grate inlet that will collect flow from the building roof and most of the parking area. The inlet will
connect to a private storm sewer pipe that will discharge into an existing public storm sewer inlet in
College Main.
The existing inlets in College Main will be converted from 5' recessed curb inlets to gutter grate inlets
which can provide the capture of equivalent flow as the curb inlet, see Appendix B2 for inlet sizing. The
data in Appendix B2 shows the proposed inlet will capture more than the existing inlet under any flow
occurrence. The conversion from curb inlets to grate inlets is necessary due to conflicts with driveway
locations.
The site does not require detention based on the Unified Stormwater Design Guidelines, Section 11.3.b.3
Small Lot. Both lots in the development are platted lots less than one acre and the proposed flow patterns
for the stormwater runoff from the development will not cause any increase in flooding conditions to the
interior of existing building structures, including basement areas, for storms of magnitude up through the
100 year event. A letter addressing the detention requirements is included as Appendix C.
COORDINATION & STORMWATER PERMITTING
The project will not require a permit to be prepared to comply with the Texas Commission for
Environmental Quality storm water permitting for the construction site, because the site is less than 1 acre.
No other permits are anticipated for this project.
DRAINAGE DESIGN
General Information: Stormwater runoff from each lot will flow into proposed grate inlets in the
parking areas, then into private storm sewer pipes which discharge into existing
inlets in College Main. The runoff from the building roofs will be piped directly
into the proposed grate inlets. See Appendix B 1 and B2 for grate inlet and pipe
sizing calculations.
Storm Sewer Drainage Analysis
T, Methodology:
TR 55
T, Minimum:
10 minutes
Design Storm Events:
10 & 100-year (Private Storm Sewer)
Pipe Materials:
HDPE Pipe
Manning's n Value:
0.012
Runoff Coefficients:
0.40 Undeveloped Property, 0.35 Landscape Areas & 0.95 Pavement Areas
Design Constraints:
Max. water depth in the parking lot = 6 in. or 0.5 ft. for 100 year storm event.
Min. flow velocity = 2.5 fps
Max, flow velocity = 15 fps Design for 25-year storm with 1 foot of freeboard
Rational Equation: The rational equation is utilized to determine peak storm water runoff rates for
the storm sewer system design.
Page 2 of 3
Drainage Report
College Main Lofts
College Station, Texas
March'7, 2012
Q = CIA
Q = Flow (cfs)
A = Area (acres)
C = Runoff Coefficient
I = Rainfall Intensity (in/hr)
Design Software: Excel spreadsheets, AutoCAD Hydraflow Express
The software was used to compute private grate inlet sizing, flowrates and
velocities through each storm sewer pipe, and equivalent grate inlet sizing for
the conversion of the existing curb inlets.
Design Results: The data presented in the Appendices indicates the development is in
accordance with the requirements of the design guidelines.
Applicable Exhibits: Exhibit A — Pre -Development Drainage Area Map
Exhibit B — Post -Development Drainage Area Map
Exhibit C — Site Drainage Area Map
Appendix A — Drainage Area Summary
Appendix B 1 — Private Inlet Design Summary
Appendix B2 — Private Storm Sewer Design Summary
Appendix B3 — Existing Inlet Conversion Summary
Appendix C — Detention Requirements Letter
The development will function within the requirements and restrictions of the BCS Drainage Design
Guidelines.
CERTIFICATION
"This report for the drainage design of The College Main Lofts, was prepared by me in accordance
with the provisions of the Bryan/College Station Unified Drainage Design Guidelines for the owners
of the property. All licenses and permits required by any and all state and federal regulatory
agencies for the proposed drainage improvements have been issued."
3�
F-12327
SCHULTZ ENGINEERING, LLC,
Joseph P Schu tz, P.E.
Page 3 of 3
EXHIBIT A
Pre -Development Drainage Area Map
50 25 0 50
SCALE IN FEET
J
408 COLLEGE
MAIN
\ 0.14 ACRES
i
I I
I
1
J
_c NLrRo "w= NLk-
COLLEGEa s ,n, aim eam D C NO co'" ., MAIN
� CANN
m ol-
J, J
--
403 COLLEGE I
MAI
0.17 ACRES I \
a I
L I
1 0 � IiII
I z-
Schultz Engineering, LLC
4'. Lw .'SM A
TX7M5
.5�8e5blbn.
$IIMEY[➢
OE$I..
1 .1.
MMiOVFD1
DATE
KERR
DLO
Dw
JPS
12-10
MARCH 2012
T
�tw=mm -
— — EXISTING 2' CONTOURS
E- FLOW DIRECTION
PARCEL BOUNDARY
PROJECT SITE BOUNDARY
DRAINAGE AREA BOUNDARY
eDRAINAGE AREA LABEL
\l�
COLLEGE MAIN LOFTS -- SCALE EXHIBIT
W.C. BOYETT ESTATE PARTITION PRE —DEVELOPMENT
BLOCK 4, LOT 5, BLOCK 5, LOT 9 NONRONTN 1:zao
BRYAN, TEXAS DRAINAGE AREA MAP „D,,,NDE�,E: ,:,
HU NAME: 12-1m
FA
EXHIBIT B
Post -Development Drainage Area Map
50 25 0
SCALE IN FEET
50
408 COLLEGE
MAIN
\ 0.14 ACRES
n
I
—Z — PROPOSED DEVELOPMENT /
DISCHARGES INTO EXISTING /
STORM SEWER INLET FROM /
PRIVATE ON SITE STORM
h_ SEWER
� T T
( \\
403 COLLEGE I
MAI
\ \ 0.17 ACRES
� a
o
}
Schultz Engineering, Ll C
iib Lagnin.9uXaA
Ctleyobbtlm. iXiiWS
sllfivevEo DESIDNED D�Ml
,wrnoY£o I.NM DniE
KERR OLD DLDJPS 12-IW MARCH 2012
I
COLLEGE MAIN F
goo T i
`.-4ow
1 LEGEND
i — — — — EXISTING 2' CONTOURS
FLOW DIRECTION
\ (� PARCEL BOUNDARY
J PROJECT SITE BOUNDARY
II
0 DRAINAGE AREA BOUNDARY
DRAINAGE AREA LABEL
�r e
COLLEGE MAIN LOFTS TIM SCALE EXHIBIT
W.C. BOYETT ESTATE PARTITION POST —DEVELOPMENT"
BLOCK 4, LOT 5, BLOCK 5, LOT 9 IW T71NGS 1.z00
BRYAN, TEXAS DRAINAGE AREA MAP ,LD,,,RDs ,.,1 B
FIIE NPME: 12-1 Bd'
EXHIBIT C
Site Drainage Area Map
40 20 0 40
SCALE IN FEET
PROPOSED
408 COLLEGE MAIN--�
BUILDING
\ 408 COLLEGE-,,,,
MAIN
\ 0.14 ACRES
EXISTING CURB INLETS
I I TO BE CONVERTED TO- <
GRATE INLETS
r'
\ \
\ PROPOSED
403 COLL BUILDING
403 COL LEGMAINE
% \ / 0.17 ACRES
J \ �
Schultz Engineering, LLC
RlW Lp .,...A
�90Sle0.n,lX7M5
sumsyso
oum.
auwR
AnP110
IRN0,
onre
KERR
OLD
DLD
JPS
12-1w
M RCH 2O12
PROPOSED GRATE
NLET 3 (DA 408)
PARKING ONLY
r�
A
PROPOSED PIPE 408
CONTRIBUTING DA 503)
PARKING AND BUILDING
° EXISTING
STORM SEWER
PROPOSED PIPE 403
(CONTRIBUTING DA 503)
PARKING AND BUILDING
COLLEGE MAIN
V)
0
U
EXISTING 2' CONTOURS
PROPOSED GRATE I F FLOW DIRECTION
> `1 NLET 1 (DA 403) a I
PARKING ONLY w
PARCEL BOUNDARY
+1� PROJECT SITE BOUNDARY
4
\\ DRAINAGE AREA BOUNDARY
.rya..;=,,.` +• ``
1 DRAINAGE AREA LABEL
COLLEGE MAIN LOFTS SCALE EXHIBIT
W.C. BOYETT ESTATE PARTITION SITE RT.A c
BLOCK 4, LOT 5, BLOCK 5, LOT 9 Tll..
BRYAN, TEXAS DRAINAGE AREA MAP ELD,,,DD ,„
Fl..E: 12-10
APPENDIX A
Drainage Area Summary
IG
.T
:v
m
LL
c
O
C
Y
G
V
G
l0 r
W N
d E
M �
rn
aU)�
W
CL o c
2
d
W
0
O
N
O
O
H
R
- z
c
m
y
ro
m
ro
m
c
m
co
v
°
°
d
v
5
;
v
0
40
000+00
E
r
IL
a
IL
°
N
v
co
m
rn
.La
0
0
0
o
o
0
N
fV
IV
O
O
O
O
ZM
a
it Y
L
c
�
c
N
y
C TVJ
o
v V C
N
O N
`
m
g o
d c c
■
k
)
�
J#cqq
!
C.
& f
!
k
!
q
a
J
}
�
\
V:
a°
! I
/
c
a
a
0
!
/
2A
!°
;
�cE
/
\
g
$
�
ƒ
#
#
L
f0{CL
LU
\
Ir
Et46
o
�f
;*
7\
§
«
)
APPENDIX B2
Private Storm Sewer Design Summary
ƒ�
2
°
2
/
§
�$
/
>F
\
f
C,
/
\
Im
)
§
§
o
2
06
0
\
t
f
=
2
04
)f
)t
a
k)
k—
APPENDIX B3
Existing Inlet Conversion Summary
APPENDIX C
Detention Requirements Letter
i
Schultz Engineering, LLC
Office: 979.764.3900
Fax: 979.764.3910
March 7, 2012
Alan Gibbs, P.E.
City Engineer
City of College Station
1101 Texas Avenue
College Station, TX 77840
Re: College Main Lofts — Detention Requirements
Dear Mr. Gibbs:
The College Main Lofts project does not require detention per the Unified Stormwater Design Guidelines,
Section IL3.b.3 Small Lot. Both lots in the development are platted lots less than one acre, therefore the
development is not subject to stormwater detention requirements of the Unified Stormwater Design
Guidelines.
"I have conducted a topographic review and field investigation of the existing and
proposed flow patterns for stormwater runoff from College Main Lofts to the
main stem of Burton Creels At build -out conditions allowable by Zoning,
restrictive covenant, or plat note, the stormwater flows from the subject
subdivision or site project will not cause any increase in flooding conditions to the
interior of existing building structures, including basement areas, for storms of
magnitude up through the 100year event."
If you have any questions, please do not hesitate to call
Very truly yours,
Schultz Engineering, LLC.
Joe Sc Itz, P.E.
Civil ngineer
- 3- 7,
F-12327
SCHULTZ ENGINEERING, LLC.
P.O. Box 11995 • College Station, Texas 77842
schultzengineeringllc.com
12 -LA8
Date test completed
Time completed
Test completed by
College Station Utilities
Reliable, Affordable, Cornrnt►nity Owned
Thursday April 11, 2013
11:00 A.M.
Justin Tamplin, Howard Mitchell
Comments Initial
College Station Utilities
Reliable, Affordable, Community Owned
Date test completed Thursday July 5, 2012
Time completed 2:00 P.M.
Test completed by Justin Tamplin and Vincent Rodriquez
Witness
HYDRANT
Location 418 College Main/315 College Main
Nozzle size 2.5
Hydrant number A-010/A--038
Pitot reading in PSI 45/52
Flow in G.P.M. 1130/1150
TIC HYDRANT
Location 405 Cross
Hydrant number A-066
Static PSI 72
Residual PSI
Comments