HomeMy WebLinkAboutDRAINAGE REPORT 1
Drainage Report
for
Castlegate Subdivision - Section 5, Phase 1
College Station, Texas
December 2003
Developer.
Greens Prairie Investors, Ltd.
By Greens Prairie Associates, LLC
4490 Castlegate Drive
College Station, Texas 77845
(979) 690 -7250
Prepared By:
TEXCON General Contractors
1707 Graham Road
College Station, Texas 77845
(979) 764 -7743
CERTIFICATION
I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this
report for the drainage design for the Castlegate Subdivision - Section 5, Phase 1, was
prepared by me in accordance with the provisions of the City of College Station Drainage
Policy and Design Standards for the owners hereof.
r ., —
Ginge A Urso, P.E.
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IJOSEPHP.SCHUL
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moo 65889
O -0,4:• sTE��; .• �� Jose P. S ultz, P.E.
`` ‘\�ONAL r a
1 2 - IS -03
TABLE OF CONTENTS
DRAINAGE REPORT
CASTLEGATE SUBDIVISION - SECTION 5, PHASE 1
CERTIFICATION 1
TABLE OF CONTENTS 2
LIST OF TABLES 2
INTRODUCTION 3
GENERAL LOCATION AND DESCRIPTION 3
FLOOD HAZARD INFORMATION 3
DEVELOPMENT DRAINAGE PATTERNS 3
DRAINAGE DESIGN CRITERIA 3
STORM WATER RUNOFF DETERMINATION 4
DETENTION FACILITY DESIGN 6
STORM SEWER DESIGN 6
CONCLUSIONS 7
APPENDIX A 8
Time of Concentration Equations & Calculations
APPENDIX B 12
Storm Sewer Inlet Design Calculations
APPENDIX C 15
Storm Sewer Pipe Design Calculations
EXHIBIT A 28
Pre - Development Drainage Area Map
EXHIBIT B 30
Post - Development Drainage Area Map — Detention Evaluation
EXHIBIT C 32
Post - Development Drainage Area Map — Storm Sewer Design
LIST OF TABLES
TABLE 1 — Rainfall Intensity Calculations 4
TABLE 2 — Time of Concentration (tc) Equations 4
TABLE 3 — Pre - Development Runoff Information 5
TABLE 4 — Post - Development Runoff Information — Detention Evaluation 5
TABLE 5 — Post - Development Runoff Information — Storm Sewer Design 5
DRAINAGE REPORT
• CASTLEGATE SUBDIVISION - SECTION 5, PHASE 1
INTRODUCTION
The purpose of this report is to provide the hydrological effects of the construction of the
Castlegate Subdivision - Section 5, Phase 1, and to verify that the proposed storm drainage
system meets the requirements set forth by the City of College Station Drainage Policy and
Design Standards.
GENERAL LOCATION AND DESCRIPTION
The project is located on a portion of a 111.46 acre tract located west of State Highway 6 along
the north side of Greens Prairie Road in College Station, Texas. This report addresses Phase 1
of Section 5 of this subdivision, which is made up of 18.72 acres. Section 5 is located adjacent
to Castlegate Section 4 along Castlegate Drive. The site is predominantly wooded. The
existing ground elevations range from elevation 308 to elevation 332. The general location of
the project site is shown on the vicinity map in Exhibit A.
FLOOD HAZARD INFORMATION
The project site is located in the Spring Creek branch of the Lick Creek Drainage Basin. Most
of the proposed developed area of the site is located in a Zone X Area according to the Flood
Insurance Rate Map prepared by the Federal Emergency Management Agency (FEMA) for
Brazos County, Texas and incorporated areas dated February 9, 2000, panel number
48041CO205 -D. This area is shown on Exhibit A as the 100 -year floodplain limit. Also shown
on this exhibit are the floodway limits as determined by the Castlegate Floodplain Analysis
Report which was previously submitted. The Flood Hazard Area within this development has
been designated as Greenway Area, which will have no development and it will be left in its
current condition.
DEVELOPMENT DRAINAGE PATTERNS
Prior to development, the storm water runoff for Section 5, Phase 1 flows in two different
directions. A majority of the runoff flows in a northwesterly direction until it enters a tributary
of Spring Creek. Ultimately, this runoff flows into Spring Creek and then north to the proposed
regional detention facility. Refer to the vicinity map in Exhibit A for the location of this
regional detention facility. The remainder of the runoff from this site flows in a northeasterly
direction into the Greens Prairie Road right -of -way.
DRAINAGE DESIGN CRITERIA
The design parameters for the storm sewer and detention facility analysis are as follows:
• The Rational Method is utilized to determine peak storm water runoff rates for the storm
sewer design and detention facility analysis.
• Design Storm Frequency
Storni sewer system 10 and 100 -year storm events
Detention facility analysis 5, 10, 25, 50 and 100 -year storm events
• Runoff Coefficients
Pre- development C = 0.30
Post - development (single family residential) C = 0.55
• Rainfall Intensity equations and values for Brazos County can be found in Table 1.
• Time of Concentration, t, — Calculations are based on the method found in the TR -55
publication. Refer to Table 2 for the equations and Appendix A for calculations. The
runoff flow path used for calculating the pre- development time of concentration is shown in
Exhibit A, and the flow paths used for the post- development times of concentration are
found in Exhibits B & C. For smaller drainage areas, a minimum t, of 10 minutes is used to
determine the rainfall intensity values.
STORM WATER RUNOFF DETERMINATION •
The peak runoff values were determined in accordance with the criteria presented in the
previous section for the 5, 10, 25, 50, and 100 -year storm events. The drainage areas for the
pre- development condition are shown on Exhibit A. The drainage areas for post- development
are shown on Exhibit B for the detention facility analysis and on Exhibit C for the storm sewer
design. Pre - development and post - development runoff information for the detention facility
evaluation are summarized in Tables 3 & 4, respectively. Post - development runoff conditions
for the storm sewer design are summarized in Table 5.
TABLE 1 — Rainfall Intensity Calculations
Rainfall Intensity Values (in /hr)
Storm t, = 1= b / (tc +d)
Event 10 min 1 = Rainfall Intensity (in /hr)
1 7.693
110 8.635 = L/(V" 60)
1 25 9.861 t = Time of concentration (min)
1 50 11.148 L = Length (ft)
I100 11.639 V = Velocity (ft/sec)
Brazos County:
5 Year storm 10 year storm 25 year storm 50 year storm 100 year storm
b= 76 b= 80 b= 89 b= 98 b= 96
d = 8.5 d = 8.5 d = 8.5 d = 8.5 d = 8.0
e = 0.785 e = 0.763 e = 0.754 e = 0.745 e = 0.730
(Data taken from State Department of Highways and Public Transportation Hydraulic Manual, page 2 -16)
TABLE 2 — Time of Concentration (tO Equations
The time of concentration was determined using methods found in TR -55, "Urban
Hydrology for Small Watersheds.'' The equations are as follows:
Time of Concentration: Tc = Tt(shect flow) + Tt(conccntrated sheet I1(m)
where: T = Travel Time, minutes
4
For Sheet Flow: T = 0.007 (n L) ° ' 8
(PZ) s 0.4 where: T = travel time, hours
n = Manning's roughness coefficient
L = flow length, feet
Pz = 2 -year, 24 -hour rainfall = 4.5"
s = land slope, ft /ft
For Shallow Concentrated Flow: T, = L / (60 *V)
where: T = travel time, minutes
V = Velocity, fps (See Fig 3 -1, App. E)
L = flow length, feet
Refer to Appendix A for calculations.
•
TABLE 3 - Pre - Development Runoff Information
5 year storm 10 year storm 25 year storm 50 year storm 100 year storm
Area Area # C 15 Q5 1 10 Q10 1 25 025 1 50 Q50 1 100 Q100
(acres) (min) (in /hr) (cfs) (in /hr) (cfs) (in /hr) (cfs) (in /hr) (cfs) (in /hr) (cfs)
101 6.1 0.3 32.3 4.135 7.57 4.722 8.64 5.432 9.94 6.184 11.32 6.462 11.83
102 27.1 0.3 40.8 3.564 28.97 4.087 33.23 4.710 38.29 5.371 43.67 5.620 45.69
TABLE 4 - Post - Development Runoff Information - Detention Evaluation
Area C k 5 year storm 10 year storm 25 year storm 50 year storm 100 year storm
Area # (acres) l 15 Q5 1 10 Q10 its Q25 1 50 Q50 1 100 Q100
A A2 Total C1 C2 Grob (min) (in /hr) (cfs) (in /hr) (cfs) (in /hr) (cfs) (in /hr) (cfs) (in /hr) (cfs)
201 0.77 5.67 6.44 0.55 0.3 0.33 32.3 4.135 8.78 4.722 10.03 5.432 11.54 6.184 13.14 6.462 13.73
202 11.26 6.36 17.62 0.55 0.3 0.46 40.8 3.564 28.87 4.087 33.11 4.710 38.15 _ 5.371 43.51 _ 5.620 45.53
TABLE 5 - Post - Development Runoff Information - Storm Sewer Design
5 year storm 10 year storm 25 year storm 50 year storm 100 year storm
Area tc
Area # C 15 Q5 1 10 Q10 1 25 Q25 1 50 Q50 1 100 Q1oo
(acres) (min) (inlhr) (cfs) (in /hr) (cfs) (inlhr) (cfs) (in /hr) (cfs) (in /hr) (cfs)
1 1.03 0.55 10 7.693 4.36 8.635 4.89 9.861 5.59 11.148 6.32 11.639 6.59
2 1.96 0.55 10 7.693 8.29 8.635 9.31 9.861 10.63 11.148 12.02 11.639 12.55
3 3.11 0.55 10 7.693 13.16 8.635 14.77 9.861 16.87 11.148 19.07 11.639 19.91
4 1.73 0.55 10 7.693 7.32 8.635 8.22 9.861 9.38 11.148 10.61 11.639 11.07
5 1.16 0.55 10 7.693 4.91 8.635 5.51 9.861 6.29 11.148 7.11 11.639 7.43
6 1.15 0.55 14.0 6.597 4.17 7.437 4.70 8.508 5.38 9.635 6.09 10.053 6.36
7 0.64 0.55 10 7.693 2.71 8.635 3.04 9.861 3.47 11.148 3.92 11.639 4.10
8 1.37 0.55 10 7.693 5.80 8.635 6.51 9.861 7.43 11.148 8.40 11.639 8.77
9 0.90 0.55 10 7.693 3.81 8.635 4.27 9.861 4.88 11.148 5.52 11.639 5.76
10 0.74 0.55 10 7.693 3.13 8.635 3.51 9.861 4.01 11.148 4.54 11.639 4.74
11 0.62 0.55 10 7.693 2.62 8.635 2.94 9.861 3.36 11.148 3.80 11.639 3.97
12 1.89 0.55 10 7.693 8.00 8.635 8.98 9.861 10.25 11.148 11.59 11.639 12.10
13 0.13 0.55 10 7.693 0.55 8.635 0.62 9.861 0.71 11.148 0.80 11.639 0.83
14 1.71 0.55 _ 10 7.693 7.24 8.635 8.12 9.861 9.27 11.148 10.48 11.639 10.95
15 2.06 0.55 10 7.693 8.72 8.635 9.78 9.861 11.17 11.148 12.63 11.639 13.19
16 2.12 0.55 10 7.693 8.97 8.635 10.07 9.861 11.50 11.148 13.00 11.639 13.57
DETENTION FACILITY DESIGN
The detention facility handling the runoff from this site is a regional facility designed by LJA
Engineering & Surveying, Inc. Also, a detention pond was constructed upstream of Castlegate
Drive to reduce the peak flow resulting from the Castlegate development. The detention
facility is located adjacent to Spring Creek prior to Spring Creek entering the State Highway 6
right -of -way. A detention facility is not needed for the runoff that flows into the Greens Prairie
Road right -of -way for Section 5, Phase 1 because the area which flows in this direction was
reduced by the construction of the storm sewer system for Section 4, Phase 2. The developer
did not desire a detention pond in Section 4, so the runoff was collected by the storm sewer
system and diverted north to a tributary of Spring Creek and then to the regional detention
facility. This facility was designed for this flow to be diverted to the facility.
A comparison of the pre- development (Area 102) and post- development (Area 202) flows for
Discharge Point #1 shows a reduction in the peak runoff for all storm events, including a
reduction of 0.16 cfs for the 100 -year storm event.
A comparison of the peak flow values for Discharge Point #2 shows a slight increase of 1.9 cfs
in the runoff for the 100 -year storm event, from 11.83 cfs to 13.73 cfs. This is due to the
development of 0.77 acres of this drainage area and a slight increase in the post- development
area draining to Discharge Point #2. A detention pond is proposed for Phase 2 of Section 5,
which will reduce the peak runoff to less than or equal to the pre- development runoff. In our
opinion, the increase in the peak runoff due to the development of Phase 1 is not significant
enough to warrant that the detention pond for Phase 2 be constructed at this time.
STORM SEWER DESIGN
The storm sewer piping for this project has been selected to be Reinforced Concrete Pipe
(RCP) meeting the requirements of ASTM C -76, Class III pipe meeting the requirements of
ASTM C -789. The curb inlets and junction boxes will be cast -in -place concrete.
Appendix B presents a summary of the storm sewer inlet design parameters and calculations.
The inlets were designed based on a 10 -year design storm. As per College Station guidelines,
the capacities of inlets in sump were reduced by 10% to allow for clogging.
Inlets for the residential streets were located to maintain a gutter flow depth of 5" or less. This
design depth will prevent the spread of water from reaching the crown of the road for the 10-
year storm event. Refer to Appendix B for a summary of the gutter flow depths. The runoff
intercepted by the proposed storm sewer inlets was calculated using the following equations.
The depth of flow in the gutter was determined by using the Straight Crown Flow equation.
The flow intercepted by Inlets 5 -3 & 5 -4 was calculated by using the Capacity of Inlets On
Grade equation. These equations and resulting data are summarized in Appendix B. The
capacities for the inlets in sump (Inlets 5 -1, 5 -2, 5 -9 & 5 -10) were calculated using the Inlets in
Sumps, Weir Flow equation with a maximum allowable depth of 7" (5" gutter flow plus 2"
gutter depression). These equations and the resulting data are also summarized in Appendix B.
The area between the right -of -way and the curb line of the streets will be graded as necessary to
provide a minimum of 6" of freeboard above the curb line. This will ensure that the runoff
from the 1 00-year storm event will remain within the street right -of -way.
Appendix C presents a summary of the storm sewer pipe design parameters and calculations.
All pipes are 18" in diameter or larger. For pipes with 18" and 24" diameters, the cross-
sectional area is reduced by 25 %, as per College Station requirements. A summary of how this
was achieved is shown in Appendix C as well. The pipes for the storm sewer system were
designed based on the 10 -year storm event, and they will also pass the 100 -year storm event.
Based on the depth of flow in the street determined for the 100 -year storm event, this runoff
will be contained within the street right -of -way until it enters the storm sewer system. As
required by College Station, the velocity of flow in the storm sewer pipe system is not lower
than 2.5 feet per second, and it does not exceed 15 feet per second. As the data shows, even
during low flow conditions, the velocity in the pipes will exceed 2.5 feet per second and
prevent sediment build -up in the pipes. The maximum flow in the storm sewer pipe system
will occur in Pipe No. 1. The maximum velocity for the pipe system in this development will
be 13.4 feet per second and will occur in Pipe No. 1'. Appendix C contains a summary of the
pipe calculations as well as flow diagrams mapping the flows through the storm sewer system
for the 10 and 100 -year events.
CONCLUSIONS
The construction of this project will increase the storm water runoff from this site. The
proposed storm sewer system should adequately control the runoff and release it into existing
drainages. As shown in the Castlegate Floodplain Analysis, the Castlegate Subdivision does
not have a significant effect on the 100 -year floodplain water surface elevations or the
floodplain limits. The regional detention facility should adequately control the peak post -
development runoff so that it will not have any impact on the properties downstream of the
Crowley Tract. The runoff to the south into the Greens Prairie Road right -of -way has also been
addressed in this report, and there should be no flood damage to downstream or adjacent
landowners resulting from this development.
APPENDIX A
Time of Concentration Equations & Calculations
8
Pre - Development
Time of Concentration Calculations
Refer to Exhibit A for flow paths used for calculations.
Pre - Development Drainage Area #101:
Sheet Flow: Flow length = 300' = L
Slope = 1.8%
n = 0.24, dense grass
P2 = 4.5"
t, = 0.007 (0.24 * 300)
(4.5) (0.018)
t = 0.504 hours = 30.2 minutes
Shallow Concentrated Flow: Flow length = 285' = L
Slope = 2.2%
For unpaved surface at 2.2 %, Velocity (V) = 2.3 fps (see Fig. 3 - 1)
t = 285'/(60 *2.3) = 2.1 minutes
T, = 30.2 + 2.3 = 32.3 minutes
Pre - Development Drainage Area #102:
Sheet Flow: Flow length = 300' = L
Slope = 1.75%
-4 t = 0.509 hours = 30.6 minutes
Shallow Concentrated Flow: First segment flow length = 985' = L
Slope = 1.75%
For unpaved surface at 1.75 %, Velocity (V) = 2.15 fps (see Fig. 3 - 1)
Similarly:
Second segment flow length = 360' = L
Slope = 2.10 % V =2.3 fps
-4 t = 985'/(60 *2.15) + 360'/(60 *2.3) = 10.2 minutes
T, = 30.6 + 10.2 = 40.8 minutes
Post- Development
Time of Concentration Calculations
Refer to Exhibits B & C for flow paths used for calculations.
Post - Development Drainage Area #201:
Sheet Flow: Flow length = 300' = L
Slope = 1.8%
t = 0.504 hours = 30.2 minutes
Shallow Concentrated Flow: Flow length = 285' = L
Slope = 2.2%
For unpaved surface at 2.2 %, Velocity (V) = 2.3 fps (see Fig. 3 -1)
- � t = 285'/(60 *2.3) = 2.1 minutes
- 3 T, = 30.2 + 2.3 = 32.3 minutes
Post- Development Drainage Area #202:
T, calculation is the same as for Pre Development Drainage Area #102.
Post - Development Drainage Area #6:
Sheet Flow: Flow length = 95' = L
Slope = 3.0%
n = 0.24, dense grass
P2 = 4.5"
t = 0.007 (0.24 * 95)
(4.5) (0.03)
-4 t, = 0.164 hours = 9.8 minutes
Gutter Flow: Flow length = L = 78'
Slope = 0.8%
For paved surface at 0.8 %, Velocity (V) = 1.8 fps (see Fig. 3 - 1)
Similarly:
L = 272' @ 1.85% -' V = 2.8 fps
L = 225' @ 1.00% -' V = 2.0 fps
t = 78'/(60* 1.8) + 272'/(60 *2.8) + 225'/(60 *2.0) = 4.2 minutes
-� T, = 9.8 + 4.2 = 14.0 minutes
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APPENDIX B
Storm Sewer Inlet Design Calculations
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Castlegate Subdivision - Section 5
Depth of Flow in Street Gutter
10 -year storm 100 -year storm
Gutter A Slope Qio Y10-actual Q1oo Y1oo
Location (acres) (ft/ft) (cfs) (ft) (in) (cfs) (ft) (in)
�, ; ,
U U,P,. ?3 : ,__ . :_ . " lit)( -Y 4 � .>
ca L
cn
N C 1 1.15 0.55 0.008 5.46 0.378 4.53 7.36 0.423 5.07
o C2 1.38 0.55 0.008 6.55 0.405 4.85 8.83 0.452 5.43
Al 0.13 0.55 0.0100 0.62 0.152 1.82 0.83 0.170 2.04
Byp. A4 +A6+ A2 1.03 0.55 0.0100 4.89 0.330 3.96 6.59 0.369 4.43
A3 1.32 0.55 0.0080 6.27 0.377 4.53 8.45 0.422 5.06
Byp F1 +F2+ A4 2.12 0.55 0.0125 10.07 0.415 4.97 13.57 0.464 5.56
Byp. A6 + A5 0.59 0.55 0.0080 2.80 0.279 3.35 3.78 0.312 3.74
A7 +C2 +C1+ A6 3.11 0.55 0.0280 14.77 0.411 4.94 19.91 0.460 5.52
A7 0.55 0.55 0.0280 2.61 0.215 2.58 3.52 0.240 2.88
A8 1.89 0.55 0.0100 8.98 0.414 4.97 12.10 0.463 5.56
D1 1.15 0.55 0.0100 5.46 0.344 4.12 7.36 0.384 4.61
3 D2 1.61 0.55 0.0100 7.65 0.390 4.68 10.31 0.436 5.23
J N D3 1.16 0.55 0.0100 5.51 0.345 4.14 7.43 0.386 4.63
D4 0.64 0.55 0.0100 3.04 0.276 3.31 4.10 0.309 3.70
tatir) p -' 1 ,tr 55 0 0143 1 ; 5/ 5 7 4 49
FL tuft 8 . . . X55 0 0'00 7 51 , 7.30 . .
.tore _ r 0'00 4 2: 9
1 .0 25 J. 1.. f l . U. 3
F1+ Future F2 2 06 9 55 0.0125 9 78 0 4 10 t 92
Transverse (Crown) slope ( ft/ft)
for cul -de -sac streets = 0.0380
for loop street = 0.0330
Straight Crown Flow (Solved to find actual depth of flow in gutter, y):
Q= 0.56 *(z /n) * S 112 * y = {Q / [0.56 * (z/n)* S 112 ]} 318
n = Roughness Coefficient = 0.018
S = Street/Gutter Slope ( ft/ft)
y = Depth of flow at inlet (ft)
z = Reciprocal of crown slope:
for cul -de -sac streets = 26
for loop street = 30
APPENDIX C
Storm Sewer Pipe Design Calculations
1 ! 1
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City of College Station requirement to Reduce Cross - Sectional Area of 18" & 24" Pipes by 25%
Using Mannings Equation from page 48 of the College Station Drainage Policy & Design Standards Manual:
Q = 1.49/n * A * R S 112
Q = Flow Capacity (cfs)
18" Pipe:
Pipe size (inches) = 18
Wetted Perimeter W (ft) = 4.71
Cross - Sectional Area A, (ft = 1.766
Reduced Area A (ft = 1.325
Hydraulic Radius R = A/W (ft) = 0.375
Reduced Hydr Radius RR = AR/W (ft) = 0.281
Roughness Coefficient n = 0.014
Friction Slope of Conduit Sf, (ft/ft) = 0.01
Example Calculation:
Slope Flow Capacity Reduced Flow Capacity % Difference
S Q Qreduced Qreduced /Q
0.005 6.91 4.28 0.619
0.006 7.57 4.69 0.619
0.007 8.18 5.06 0.619
24" Pipe:
Pipe size (inches) = 24
Wetted Perimeter W (ft) = 6.28
Cross - Sectional Area A, (ft = 3.14
Reduced Area AR, (ft = 2.355
Hydraulic Radius R = A/W (ft) = 0.5
Reduced Hydr Radius RR = A (ft) = 0.375
Roughness Coefficient n = 0.014
Friction Slope of Conduit Sf, (ft/ft) = 0.01
Example Calculation:
Slope Flow Capacity Reduced Flow Capacity % Difference
S Q °reduced °reduced'Q
0.005 14.89 9.22 0.619
0.006 16.31 10.1 0.619
0.007 17.61 10.9 0.619
Conclusion:
Multiply actual Q in 18" & 24" pipes by 1.615 to reflect a 25% reduction in the
cross- sectional area called for on page 47, paragraph 5 of the College Station
Drainage Policy & Design Standards manual.
Castlegate Subdivision
Section 5 - Pipe Flow Diagram
Q10 (cfs)
Future Devel. 17.90
Pipe 5 17.90 Inlet 5 -9 j 13.73
Inlet 5 -4 10.07 Pipe 9 i 13.73
Pipe 4 27.97 Inlet 5 -10 7.74
Junc Box 1 Pipe 8 21.47
1
Pipe 3 27.97 Inlet 5 -3 10.57 ) Into Channel 21.5 I
Inlet 5 -2 18.40 - Pipe 7 10.57
Pipe 2 56.94
Inlet 5 -1 9.60
Pipe 1 66.54
II Into Channel 66.5 I
Castlegate Subdivision
Section 5 - Pipe Flow Diagram
Q100 (cfs)
Future Devel. 22.12
Pipe 5 22.12 Inlet 5 -9 18.50
•
Inlet 5 -4 11.38 Pipe 9 18.50
Pipe 4 33.50 Inlet 5 -10 10.46
Junc Box 1 Pipe 8 28.96
Pipe 3 33.50 Inlet 5 -3 11.32 II Into Channel 29.0 I
1
Inlet 5 -2 31.93 F— Pipe 7 11.32
1
Pipe 2 76.75
Inlet 5 -1 12.93
Pipe 1 89.68
II Into Channel 89.7 I
Pipe 1 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 36.0000 in
Flowrate 66.5400 cfs
Slope 0.0185 ft /ft
Manning's n 0.0140
Computed Results:
Depth 24.1326 in
Area 7.0686 ft2
Wetted Area 5.0372 ft2
Wetted Perimeter 69.0645 in
Perimeter 113.0973 in
Velocity 13.2096 fps
Hydraulic Radius 10.5027 in
Percent Full 67.0350 %
Full flow Flowrate 84.2396 cfs
Full flow velocity 11.9175 fps
Pipe 1 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 36.0000 in
Flowrate 89.6800 cfs
Slope 0.0185 ft /ft
Manning's n 0.0140
Computed Results:
Depth 32.3118 in
Area 7.0686 ft2
Wetted Area 6.6874 ft2
Wetted Perimeter 89.6387 in
Perimeter 113.0973 in
Velocity 13.4103 fps
Hydraulic Radius 10.7430 in
Percent Full 89.7549 %
Full flow Flowrate 84.2396 cfs
Full flow velocity 11.9175 fps
Castlegate Subdivision - Section 5, Phase 1
Co]iecje St<3C_ ion Te;;as
Pipe 2 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 36.0000 in
Flowrate 56.9400 cfs
Slope 0.0140 ft /ft
Manning's n 0.0140
Computed Results:
Depth 23.8488 in
Area 7.0686 ft2
Wetted Area 4.9703 ft2
Wetted Perimeter 68.4626 in
Perimeter 113.0973 in
Velocity 11.4559 fps
Hydraulic Radius 10.4543 in
Percent Full 66.2467 %
Full flow Flowrate 73.2816 cfs
Full flow velocity 10.3672 fps
Pipe 2 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 36.0000 in
Flowrate 76.7500 cfs
Slope 0.0140 ft /ft
Manning's n 0.0140
Computed Results:
Depth 31.3329 in
Area 7.0686 ft2
Wetted Area 6.5308 ft2
Wetted Perimeter 86.5777 in
Perimeter 113.0973 in
Velocity 11.7521 fps
Hydraulic Radius 10.8623 in
Percent Full 87.0360 %
Full flow Flowrate 73.2816 cfs
Full flow velocity 10.3672 fps
Castlegate Subdivision Section 5, Phase 1
College Station, Texas
Pipe 3 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 30.0000 in
Flowrate 27.9700 cfs
Slope 0.0125 ft /ft
Manning's n 0.0140
Computed Results:
Depth 17.7377 in
Area 4.9087 ft2
Wetted Area 3.0215 ft2
Wetted Perimeter 52.6302 in
Perimeter 94.2478 in
Velocity 9.2568 fps
Hydraulic Radius 8.2672 in
Percent Full 59.1258 %
Full flow Flowrate 42.5829 cfs
Full flow velocity 8.6749 fps
Pipe 3 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 30.0000 in
Flowrate 33.5000 cfs
Slope 0.0125 ft /ft
Manning's n 0.0140
Computed Results:
Depth 20.0518 in
Area 4.9087 ft2
Wetted Area 3.4866 ft2
Wetted Perimeter 57.4289 in
Perimeter 94.2478 in
Velocity 9.6083 fps
Hydraulic Radius 8.7424 in
Percent Full 66.8393 %
Full flow Flowrate 42.5829 cfs
Full flow velocity 8.6749 fps
Castlegate Subdivision - Section 5, Phase 1
College Station, 'Texas
Pipe 4 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 27.0000 in
Flowrate 27.9700 cfs
Slope 0.0125 ft /ft
Manning's n 0.0140
Computed Results:
Depth 19.4745 in
Area 3.9761 ft2
Wetted Area 3.0705 ft2
Wetted Perimeter 54.7897 in
Perimeter 84.8230 in
Velocity 9.1091 fps
Hydraulic Radius 8.0701 in
Percent Full 72.1280 %
Full flow Flowrate 32.1526 cfs
Full flow velocity 8.0865 fps
Pipe 4 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 27.0000 in
Flowrate 33.5000 cfs
Slope 0.0125 ft /ft
Manning's n 0.0140
Computed Results:
Depth 23.3118 in
Area 3.9761 ft2
Wetted Area 3.6496 ft2
Wetted Perimeter 64.3801 in
Perimeter 84.8230 in
Velocity 9.1790 fps
Hydraulic Radius 8.1632 in
Percent Full 86.3400 %
Full flow Flowrate 32.1526 cfs
Full flow velocity 8.0865 fps
Castl.egate Subdivision - Section 5, Phase 7
Co l lege Stay i on1 , Te as
Pipe 5 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 27.0000 in
Flowrate 17.9000 cfs
Slope 0.0065 ft /ft
Manning's n 0.0140
Computed Results:
Depth 17.8050 in
Area 3.9761 ft2
Wetted Area 2.7813 ft2
Wetted Perimeter 51.1745 in
Perimeter 84.8230 in
Velocity 6.4358 fps
Hydraulic Radius 7.8264 in
Percent Full 65.9444 %
Full flow Flowrate 23.1855 cfs
Full flow velocity 5.8313 fps
Pipe 5 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 27.0000 in
Flowrate 22.1200 cfs
Slope 0.0065 ft /ft
Manning's n 0.0140
Computed Results:
Depth 21.0918 in
Area 3.9761 ft2
Wetted Area 3.3324 ft2
Wetted Perimeter 58.5367 in
Perimeter 84.8230 in
Velocity 6.6378 fps
Hydraulic Radius 8.1978 in
Percent Full 78.1176 %
Full flow Flowrate 23.1855 cfs
Full flow velocity 5.8313 fps
Castlegate Subdivision - Section 5, Phase 1
College Station, Texas
Pipe 7 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 24.0000 in
Flowrate 17.0700 cfs
Slope 0.0120 ft /ft
Manning's n 0.0140
Computed Results:
Depth 15.3898 in
Area 3.1416 ft2
Wetted Area 2.1282 ft2
Wetted Perimeter 44.5724 in
Perimeter 75.3982 in
Velocity 8.0210 fps
Hydraulic Radius 6.8755 in
Percent Full 64.1244 %
Full flow Flowrate 23.0115 cfs
Full flow velocity 7.3248 fps
Pipe 7 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 24.0000 in
Flowrate 18.2800 cfs
Slope 0.0120 ft /ft
Manning's n 0.0140
Computed Results:
Depth 16.1548 in
Area 3.1416 ft2
Wetted Area 2.2492 ft2
Wetted Perimeter 46.1844 in
Perimeter 75.3982 in
Velocity 8.1274 fps
Hydraulic Radius 7.0128 in
Percent Full 67.3118 %
Full flow Flowrate 23.0115 cfs
Full flow velocity 7.3248 fps
Castlegate Subdivision - Section 5, Phase 1
College Station, Te
Pipe 8 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 30.0000 in
Flowrate 21.4700 cfs
Slope 0.0050 ft /ft
Manning's n 0.0140
Computed Results:
Depth 20.2456 in
Area 4.9087 ft2
Wetted Area 3.5245 ft2
Wetted Perimeter 57.8416 in
Perimeter 94.2478 in
Velocity 6.0916 fps
Hydraulic Radius 8.7744 in
Percent Full 67.4853 %
Full flow Flowrate 26.9318 cfs
Full flow velocity 5.4865 fps
Pipe 8 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 30.0000 in
Flowrate 28.9600 cfs
Slope 0.0050 ft /ft
Manning's n 0.0140
Computed Results:
Depth 27.9299 in
Area 4.9087 ft2
Wetted Area 4.7609 ft2
Wetted Perimeter 78.2997 in
Perimeter 94.2478 in
Velocity 6.0829 fps
Hydraulic Radius 8.7556 in
Percent Full 93.0998 %
Full flow Flowrate 26.9318 cfs
Full flow velocity 5.4865 fps
Castlegate Subdivision - Section 5, Phase 1
College Station, Te> :an
Pipe 9 - 10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 27.0000 in
Flowrate 13.7300 cfs
Slope 0.0050 ft /ft
Manning's n 0.0140
Computed Results:
Depth 16.2528 in
Area 3.9761 ft2
Wetted Area 2.5006 ft2
Wetted Perimeter 47.9559 in
Perimeter 84.8230 in
Velocity 5.4907 fps
Hydraulic Radius 7.5086 in
Percent Full 60.1954 %
Full flow Flowrate 20.3351 cfs
Full flow velocity 5.1144 fps
Pipe 9 - 100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape Circular
Solving for Depth of Flow
Diameter 27.0000 in
Flowrate 18.5000 cfs
Slope 0.0050 ft /ft
Manning's n 0.0140
Computed Results:
Depth 20.2096 in
Area 3.9761 ft2
Wetted Area 3.1922 ft2
Wetted Perimeter 56.4554 in
Perimeter 84.8230 in
Velocity 5.7954 fps
Hydraulic Radius 8.1422 in
Percent Full 74.8503 %
Full flow Flowrate 20.3351 cfs
Full flow velocity 5.1144 fps
Castl.egate Subdivision - Section 5, Phase 1
College Station, Texas
EXHIBIT A
Pre - Development Drainage Area Map
,ti
EXHIBIT B
Post - Development Drainage Area Map — Detention Evaluation
EXHIBIT C
Post - Development Drainage Area Map — Storm Sewer Design
,2