HomeMy WebLinkAboutDrainage ReportDrainage Report
for
The Traditions Subdivision -Phase 23
(BIO-MEDICAL WAY)
College Station, Texas
January 2013
Developer:
Bryan/Traditions, L.P.
2100 Traditions Blvd.
Bryan, Texas 77807
Ph: (979) 821-2582
Prepared By:
~==---· Schultz 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
The Traditions Subdivision -Phase 23 (Bio-Medical Way)
College Station, Texas
ENGINEER
Schultz Engineering, LLC
P.O. Box 11995
College Station, Texas 77842
Phone: (979) 764 -3900
OWNER/DEVELOPER
Bryan Commerce & Development, Inc.
P.O. Box 1000
Bryan, Texas 77805
OWNER/DEVELOPER
Bryan/Traditions, L.P.
2100 Traditions Blvd.
Bryan, Texas 77807
Ph: (979) 821-2582
GENERAL DESCRIPTION AND LOCATION
This project consists of the development of The Traditions Subdivision Phase 23 in College Station, Texas.
Phase 23 is the development of Lots l & 2, the Greenway Common Area, and Bio-Medical Way.
Traditions Subdivision Phase 23 will include the construction of utilities and other infrastructure for Bio-
Medical Way, a public street. This report will address the storm sewer system and temporary channel
sizing for Bio-Medical Way only, detention for Lots in Phase 23 will be constructed in conjunction with the
development of individual lots and will be included in a subsequent drainage reports. The detention for lots
in Phase 23 may be provided by each individual lot or in a regional detention facility.
This project is located at the end of the existing Health Science Center (HSC) Parkway, west of the
intersection of HSC Parkway and South Traditions Drive.
Area: 1.46 acres
Existing Land Use: Vacant
Proposed Land Use: Roadway
Number of Lots: NIA definition
Drainage Basin: Whites Creek Watersheds
FEMA FIRM: #48041C0285E, Dated May 16, 2012
Floodplain: None of the development lies within the floodplain.
HYDROLOGIC CHARACTERISTICS
The pre-development condition of the land is pasture. The existing drainage flow path is east and west as
the proposed roadway alignment is along an existing ridge line.
GENERAL STORMWATER PLAN
The drainage plan for Bio-Medical Way will involve the installation of a temporary drainage channel and a
storm sewer system for the curb and gutter street. The storm sewer system and temporary drainage channel
Page 1 of3
Drainage Report
The Traditions Subdivision -Phase 23 (Bio-Medical Way)
College Station, Texas
will collect and transmit the runoff to the existing Cashion Pond, east of Bio-Medical Way. Exhibit A
shows the post development topography and the runoff flow direction.
COORDINATION & STORMWATERPERMITTING
The project will require a Site Notice be prepared to comply with the Texas Commission for Environmental
Quality storm water permitting for the construction site. No other permits are anticipated for this project.
DRAINAGE DESIGN
General Information:
Street Design:
Tc Methodology:
Tc Minimum:
Design Storm Events:
Pipe Materials:
Manning's n Value:
Runoff Coefficients:
Design Constraints:
Rational Equation:
Design Software:
Storm water runoff from Bio-Medical Way will be collected by a storm sewer
system and will ultimately discharge into a tributary of Whites Creek. The
location of the drainage areas for evaluation of the gutter depth check, inlet
sizing and pipe evaluation are shown on Exhibit A. Also shown are the
locations of inlets, junction boxes, storm sewer pipes and temporary drainage
channel.
Standard cross-section (3% cross-slope, 38' B-B Roadway)
Standard curb & gutter with asphalt pavement
TR55
10 minutes
10 & 100 year events -street & storm sewer
25 & 100 year events -drainage channel
RCP, Profile gasket pipe in accordance with ASTM C443, ASTM C76, Class III
0.040 Grass lined channel
0.013 Storm sewer pipe
0.85 for proposed contributing area
Design for 25-year storm with 1 foot of freeboard -drainage channel
Max. water depth in curb = 6.0 in. or 0.5 ft.
Min. flow velocity= 2.5 fps -pipes
Max. flow velocity = 15 fps -pipes
100-yr storm runoff maintained within the ROW
25% Reduction in cross-sectional area of pipes less than 24" in diameter
The rational equation is utilized to determine peak storm water runoff rates for
the storm sewer and temporary channel design.
Q=CIA
Q =Flow (cfs)
A = Area (acres)
C = Runoff Coefficient
I = Rainfall Intensity (in/hr)
Excel spreadsheets, AutoCAD Hydraflow Express
The software was used to compute pipe capacity, flowrate and velocity through
pipes, inlet capacities, gutter depth, storm sewer pipe sizing, channel depths and
discharge data.
The requirement for a 25% reduction in cross-sectional area of pipes less than
24" diameter is achieved by using internal pipe diameters that are less than the
standard diameter. The 24" diameter pipe areas were reduced by 25% and a
Page 2 of3
Drainage Report
The Traditions Subdivision -Phase 23 (Bio-Medical Way)
College Station, Texas
Design Results:
Applicable Exhibits:
CONCLUSION
20.6" diameter pipe used in the analysis and the 18' diameter pipe areas were
reduced by 25% and a 15.6" diameter pipe was in the analysis.
The data presented in the Appendices indicates the street, storm sewer system,
and temporary drainage channel are in accordance with the requirements of the
design guidelines. See Appendix A-C for results.
Exhibit A -Drainage Area Map Post Development -Bio-Medical Way
Appendix A -Drainage Area Summary
Appendix B 1 -Storm Sewer Inlets in Sump -Design Analysis
Appendix B2 -Depth of Flow in Gutter
Appendix B3 -Pipe Design Summary
Appendix C -Temporary Drainage Channel -Design Summary
The drainage system for Bio-Medical Way will function within the requirements and restrictions of the
BCS Drainage Design Guidelines.
CERTIFICATION
"This report for the drainage design of The Traditions Subdivision -Phase 23 (Bio-Medical Way), 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."
SCHULTZ ENGINEERING, LLC.
Page 3 of3
EXHIBIT A
Drainage Area Map
Post Development
Bio-Medical Way
APPENDIX A
Drainage Area Summary
TRADITIONS PHASE 23
Drainage Area Summary
Area# Area, A
(acres)
301 0.24
302 0.22
303 0.24
304 0.22
305 0.24
306 0.24
The Rational Method:
Q=CIA
Q =Flow (cfs)
A= Area (acres)
C = Runoff Coeff.
I = Rainfall Intensity (in/hr)
Brazos County:
APPENDIXA1
c tc 10 year storm 100 year storm
110 Q10 1100 Q100
(min) (in/hr) (cfs) (in/hr) (cfs)
0.850 10.0 8.635 1.76 11 .639 2.37
0.850 10.0 8.635 1.61 11 .639 2.18
0.850 10.0 8.635 1.76 11.639 2.37
0.850 10.0 8.635 1.61 11 .639 2.18
0.850 10.0 8.635 1.76 11 .639 2.37
0.850 10.0 8.635 1.76 11.639 2.37
I = b I (tc+d)0
tc =Time of concentration (min)
tc = L/(V*60)
L = Length (ft
10 vear storm
b = 80
d = 8.5
e = 0.763
V =Velocity (ft/sec)
100 year storm
b = 96
d = 8.0
e = 0.730
APPENDIX Bl
Storm Sewer Inlets in Sump-Design Analysis
APPENDIX 81
TRADITIONS PHASE 23
Storm Sewer Inlets in Sump -Design Analysis
Inlet Length 010 010 010 0100 0100 0100*
No. ft. cfs ft. in. cf s ft. in.
1101 5 3.38 0.397 4.76 4.55 0.484 5.81
1102 5 3.38 0.397 4.76 4.55 0.484 5.81
* Back of sidewalk elevation is 7 .8" above the gutter line so 100 yr storm is contained within ROW.
Assume 10% clogging for design
APPENDIXB2
Depth of Flow in Gutter
TRADITIONS PHASE 23
Depth of Flow in Gutter
(Refer to Exhibit A fo~ Gutter Locations)
Gutter/Inlet A
Location Area# (acres)
1101A 301 0.240
1101 B 302 0.220
1102A 304 0.220
11028 303 0.240
Standard Curb -10-yr storm max design depth -6"
Transverse (Crown) slope (ft/ft)
Public Way= 0.0300
APPENDIX 82
c Slope le 110
(ft/ft) (min) (in/hr)
0.85 0.0065 10.000 8.635
0.85 0.0065 10.000 8.635
0.85 0.0065 10.000 8.635
0.85 0.0065 10.000 8.635
Straight Crown Flow (Solved to find actual depth of flow in gutter. yl:
Q = 0.56 * (z/n) * 5112 * y113 ¢ y ={QI (0.56 • (z/n) • 5112]}318
n =Roughness Coefficient= 0.018
S = StreeVGutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
z = Reciprocal of crown slope:
10-year storm
Q,. Q10 +bypass Y10.actua1 v
(cfs) (cfs) (ft) (in) (fps)
1.76 -0.235 2.82 1.91
1.61 -0.228 2.73 1.87
1.61 -0.228 2.73 1.87
1.76 -0.235 2.82 1.91
TRADITIONS PHASE 23
Depth of Flow in Gutter
(Refer to Exhibit A for Gutter Locations)
Gutter/Inlet A
Location Area# (acres)
1101 A 301 0.240
1101 B 302 0.220
1102A 304 0.220
11028 303 0.240
Transverse (Crown) slope {ft/ft)
Public Way= 0.0300
c Slope tc
(ft/ft) (min)
0.85 0.0065 10.000
0.85 0.0065 10.000
0.85 0.0065 10.000
0.85 0.0065 10.000
Straight Crown Flow !Solved to find actual depth of flow in gutter, yl:
Q = o.s& • (z/n) • s112 • y813 Q y = {Q / [0.56 • (z/n) • 5112)}318
n =Roughness Coefficient= 0.018
S = Street/Gutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
z = Reciprocal of crown slope:
38' street = 33
1100
(in/hr)
11.639
11.639
11.639
11.639
APPENDIX 82
1 DO-year stonn 100-year stonn
0100 0100 + bypass Y100 Allowable v Top of Gutter Gutter Free board
(cfs) (cfs) (ft) (in) Depth (fps) Curb FL Runoff, Elev. ft.
2.37 -0.263 3.16 6" 2.06 331.39 330.89 331.15 0.24
2.18 0.255 3.05 6" 2.02 331.39 330.89 331.14 0.25
2.18 0.255 3.05 6" 2.02 331.39 330.89 331.14 0.25
2.37 -0.263 3.16 6" 2.06 331.39 330.89 331.15 0.24
APPENDIXB3
Pipe Design Summary
TRADITIONS PHASE 23
PIPE DESIGN SUMMARY
Pipe Pipe Size Length
No. (in) (ft)
101 18 42
102 24 48.6
103 24 30
Notes
APPENDIXB3
Slope Contributing Contributing Pipes 010 V10
Drainage Areas (%) (cfs) (fps)
0.5 3.38 4.05
0.35 P101 6.76 4.21
0.35 P102 6.76 4.21
1. 18" diameter pipe are computed as for a 15.6" diameter pipe which represents a 25% reduction in pipe flow area.
2. 24" diameter pipe are computed as for a 20.8" diameter pipe which represents a 25% reduction in pipe flow area.
D10 0100 V100 0 100
(ft) (cfs) (fps) (ft)
0.78 4.55 4.27 0.97
1.12 9.10 4.37 1.44
1.12 9.10 4.37 1.44
APPENDIXC
Temporary Drainage Channel
Design Summary
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 30® 2013 by Autodesk, Inc. Thursday, Jan 10 2013
APPENDIX C -TEMPORARY DRAINAGE CHANNEL -DESIGN SUMMARY
Triangular Highlighted
Side Slopes (z: 1) = 4.00, 4.00 Depth (ft) = 1.18
Total Depth (ft) = 2.50 Q (cfs) = 7.710
Area (sqft) = 5.57
Invert Elev (ft) = 1.00 Velocity (ft/s) = 1.38
Slope(%) = 0.30 Wetted Perim (ft) = 9.73
N-Value = 0.040 Crit Depth , Ye (ft) = 0.75
Top Width (ft) = 9.44
Calculations EGL (ft) = 1.21
Compute by: Known Q
Known Q ( cfs) = 7.71
Elev (ft) Section Depth (ft
4.00 3.00
3.50 I'-,I 2.50
"\. /
"\. /
"\. /
' I,/
\.. / 3.00 2.00
' /
' / ' /
\.. I/
\.. / 2.50 1.50
' /
' ~, / ,. ..
" --/
' /
I\. / 2.00 1.00
\.. /
' /
' /
1.50 ' v
\.. / 0.50
' /
\.. /
\.. /
1.00 ' v 0.00
-·-···· ·--~--· ---··--·--·------·
0.50 -0.50
0 2 4 6 8 10 12 14 16 18 20 22 24
Reach (ft)
Channel Report
Hydraflow Express Extension for AutoCAD® Civil 30® 2013 by Autodesk, Inc. Thursday, Jan 10 2013
APPENDIX C -TEMPORARY DRAINAGE CHANNEL -DESIGN SUMMARY
Triangular Highlighted
Side Slopes (z: 1) = 4.00, 4.00 Depth (ft) = 1.25
Total Depth (ft) = 2.50 Q (cfs) = 9.100
Area (sqft) = 6.25
Invert Elev (ft) = 1.00 Velocity (ft/s) = 1.46
Slope(%) = 0.30 Wetted Perim (ft) = 10.31
N-Value = 0.040 Crit Depth, Ye (ft) = 0.80
Top Width (ft) = 10.00
Calculations EGL (ft) = 1.28
Compute by: Known Q
Known Q ( cfs) = 9.10
Elev (ft) Section Depth (ft
4.00 3.00
3.50 I\. ~ 2.50
' /
' /
' /
' / \. / 3.00 2.00
' /
' /
' /
" / I\. / 2.50 1.50
' ~ l'7 /
' ,
' --/
' /
I\. / 2.00 1.00
' /
' /
' /
' I/
\. / 1.50 0.50
\. /
" /
' /
1.00 "\.. I/ 0.00
---··------------------------·-··-·------·---·-···---------·-· , _____
----~---·-
0.50 -0.50
0 2 4 6 8 10 12 14 16 18 20 22 24
Reach (ft)