HomeMy WebLinkAboutDrainage Report11 I
Drainage Report
for
Castlegate Subdivision -Section 7, Phase 1
College Station, Texas
June 2006
Revised July 2006
Developer:
Greens Prairie Investors, Ltd.
By Greens Prairie Associates, LLC
4490 Castlegate Drive
College Station, Texas 77845
(979) 690-7250
Prepared Bv:
Civil Development, Ltd.
2900 Longmire Drive, Suite K
College Station, Texas 77845
(9 79) 764-7743
CERTIFICATION
I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this
revised report for the drainage design for the Castlegate Subdivision -Section 7, Plzase 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.
TABLE OF CONTENTS
DRAINAGE REPORT (Revised 712006)
CASTLEGATE SUBDIVISION -SECTION 7, 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 ..................................................................................................................................... 5
STORM SEWER DESIGN .................................................................................................................................................... 5
CONCLUSIONS ..................................................................................................................................................................... 6
APPENDIX A ......................................................................................................................................................................... 7
Time of Conce11tratio11 Equations & Calculations
APPENDIX B ........................................................................................................................................................................ 13
Storm Sewer fillet Desig11 Calculations
APPENDIX C ....................................................................................................................................................................... 16
Storm Sewer Pipe Design Calculations
EXHIBIT A ........................................................................................................................................................................... 27
Post-Developme11t Drai11age Area Map
LIST OFT ABLES
TABLE 1 -Rainfall Intensity Calculations .............................................................................................. 4
TABLE 2 -Time of Concentration (tc) Equations .................................................................................. 4
TABLE 3 -Post-Development Runoff Information -Storm Sewer Design ........................................... 5
INTRODUCTION
DRAINAGE REPORT (Revised 712006)
CASTLEGATE SUBDIVISION -SECTION 7, PHASE 1
The purpose of this revised report is to provide the hydrological effects of the construction of
the Castlegate Subdivision -Section 7, 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 in the Castlegate Subdivision west of State Highway 6 along the north
side of Greens Prairie Road in College Station, Texas. This report addresses Section 7, Phase 1
of this subdivision, which is made up of 18 acres, which is adjacent to Castlegate Section 5, and
has access off of Castlegate Drive. The site is predominantly wooded. The existing ground
elevations range from Elevation 308 to Elevation 334. 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
48041 C0205-D. There is Flood Hazard Area on the east and west portions of this
development. This area is shown on Exhibit A as the 100-year floodplain limit. No residential
area of this development lies within the Flood Hazard Area.
DEVELOPMENT DRAINAGE PATTERNS
Prior to development, the storm water runoff for Section 7, Phase 1 generally flows in a
northeasterly or northwesterly direction until it enters tributaries of Spring Creek. Ultimately,
this runoff flows into Spring Creek and then north to the existillg regional detention faci lity.
Refer to the vicinity map in Exhibit A for the location of this regional detention facility.
DRAINAGE DESIGN CRITERIA
The design parameters for the storm sewer and detention facility analysis are as follows:
• The Rational Method is utilized to detennine peak storm water runoff rates for the stom1
sewer design.
• Design Storm Frequency
Stotm sewer system
• Ru no ff Coefficients
10 and 100-year stonn events
Post-development (s ingle fam ily residential) C= 0.55
• Rain fa ll Intensity equations and values for Brazos County can be found in Table I.
• Time of Concentration, tc -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 paths used for calculating the post-development times of concentration for the
storm sewer design are shown on Exhibit A. For smaller drainage areas, a minimum tc 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
post-development conditions for the storm sewer design are shown on Exhibit A. Post-
development runoff conditions for the storm sewer design are summarized in Table 3. Tlte
design of the storm sewer system for Phase 1 includes the future development of Phase 2.
TABLE 1 -Rainfall Intensity Calculations
Rainfall Intensity Values (in/hr)
Storm
Event
Is
110
l2s
lso
1100
tc =
10 min
7.693
8.635
9.861
11 .148
11 .639
I = b I (tc+d)"
I = Rainfall Intensity (in/hr)
tc = U(V*60)
tc = Time of concentration (min)
L = Length (ft)
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 Hiqhwavs and Public Transportation Hydraulic Manual. page 2-16)
TABLE 2 -Time of Concentration (tc) 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:
For Sheet Flow:
For Shallow Concentrated Flow:
Refer to Appendix A for calc ul ations.
Tc = Tt(sheet now)+ T1(concentraled sheet now)
where: T1 =Travel Time, minutes
where: T1 =travel time, hours
n =Manning's roughness coefficient
L = flow length, feet
P2 = 2-year, 24-hour rainfall = 4.5"
s = land slope, ft/ft
T, = LI (60*V)
where: T, =travel time, minutes
V =Velocity, fps (See Fig 3-1 , App. A)
L = !low length, feet
TABLE 3 -Post-Development Runoff In formation -Storm Sewer Design
5 year storm 10 year storm 25 year storm 50 year storm 100 year storm le Area# A c
110 010 125 0 25 150 0 50 1100 0100 15 0 5
(acres) (min) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs)
1 0.51 0.55 10 7.693 2.16 8.635 2.42 9.861 2.77 11 .148 3.13 11 .639 3.26 -2 1.88 0.55 10 7.693 7.95 8.635 8.93 9.861 10.20 11.148 11 .53 11 .639 12 03
3 0.25 0.55 10 7.693 1.06 8.635 1.19 9.861 1.36 11 .148 1.53 11 .639 1.60
3A 1.39 0.55 10 7.693 5.88 8.635 6.60 9.861 7.54 11 .148 8.52 11 .639 8.90 -4 0.46 0.55 10 7.693 1.95 8.635 2.18 9.861 2.49 11 .148 2.82 11 .639 2.94
5 1.63 0.55 11. 7 7.180 6.44 8.074 7.24 9.229 8.27 10.441 9.36 10.897 9.77
6 1.58 0.55 21 .2 5.305 4.61 6.017 5.23 6.901 6.00 7.835 6.81 8.176 7.10 -7 0.32 0.55 10 7.693 1.35 8.635 1.52 9.861 1.74 11.148 1.96 11 .639 2.05
8 0.93 0.55 10 7.693 3.93 8.635 4.42 9.861 5.04 11 .148 5.70 11.639 5.95 ------9 0.69 0.55 10 7.693 2.92 8.635 3.28 9.861 3.74 11.148 4.23 11 .639 4.42 -------··-· 10 1.45 0.55 15.9 6.190 4.94 6.991 5.57 8.004 6.38 9.070 7.23 9.463 7.55 ---~·-----------11 0.35 0.55 10 7.693 1.48 8.635 1.66 9.861 1.90 11.148 2.15 11 .639 2.24 -------------12 2.30 0.55 21 .5 5.263 6.66 5.971 7.55 6.849 8.66 7.776 9.84 8.115 10.27
DETENTION FACILITY DESIGN
The detention facility handling the runoff from this site is a regional facility designed by LJA
Engineering & Surveying, Inc. The detention facility is located adjacent to Spring Creek prior
to Spring Creek entering the State Highway 6 right-of-way. Also, a detention pond was
constructed upstream of Castlegate Drive, noted as "existing pond" 011 Exhibit A , to reduce
the peak flow resulting from the Castlegate development.
STORM SEWER DESIGN
The storm sewer piping material for this project has been selected to be High Density Poly-
Ethylene (HOPE) pipe meeting the requirements of AASHTO M294, Type S with watertight
joints. The curb inlets will be cast-in-place concrete.
Appendix B presents a summary of the stom1 sewer inlet design parameters and calculations.
The inlets were designed based on a l 0-year design storm. As per College Station guidelines,
the capacities of inlets in sump were reduced by l 0% 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 capacities for the inlets in sump (Inlets 1, 2, 7 & 8) 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 eq uations and resulting data are summarized in Appendix B. The
flow intercepted by Inl ets 9, I 0 & I I was calculated by using the Capacity of Inlets On Grade
equation. The maximum depth in the proposed streets is 4. 91 inches for the I 0-year storm
event and 5.51 inches for the I 00-year storm event. These equations and the resulting data are
summarized in Appendi x B. The area between the ri ght-of-way and th e curb line of th e streets
will be graded as s/1011111 011 th e Gradi11g Plan to provide a minimum of 6" of frecboa rd above
the curb line. This will ensure that the runoff from the 100-year stonn 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 I 0-year stom1 event. Based on the depth of flow in the street determined
for the JOO-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 stom1 sewer pipe system will occur in Pipe No. 7. The maximum velocity for the pipe
system in this development will be 9.4 feet per second and will occur in Pipe No. 2. 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. In Appendix C, calculations
are provided that show that the existing 30" storm sewer pipe (Pipe 15) located along
Castlegate Drive has adequate capacity for the runoff from both Phases of the Section 7
development.
CONCLUSIONS
The construction of this project will increase the stonn water runoff from this site. The
proposed storm sewer system should adequately control the runoff and release it into an
existing drainage or existing storm sewer system, which discharge into tributaries of Spring
Creek. 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 existing pond also provides detention for Castlegate, and there will be 110 impact
on the downstream properties within Castlegate. 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 resulting from this development.
APPENDIX A
Time of Concentration Equations & Calculations
-, ,
Castlegate Subdivision -Section 7, Phase 1
Post-Development Time of Concentration Calculations
Revised 712006
Refer to Exhibit A for flow path locations.
Drainage Area # 5
Sheet Flow: n= 0.24 (dense grass)
P= 4.5
L= 100 Elev1= Elev2=
Ti= 0.007(L *nt" = 0.149 hours= I 8.9 min
(P)o.s*(S)o.4
Concentrated Flow: V= 2.05 fps (unpaved)
L= 240 Elev1= Elev2=
Ti= U(60*V) = 2.0 min
Gutter Flow 1: V= 3.45 fps (paved)
L= 63 Elev1= Elev2=
Ti= U(60*V) = 0.3 min
Gutter Flow 2: V= 2.50 fps (paved)
Slope=
Slope=
Slope=
L= 80 Elev1= Elev2= Slope=
Ti= U(60*V) = 0.5 min
ITc= 11.7 min
0.042
0.0150
0.0286
0.0150
Drainage Area #6
Sheet Flow: n= 0.24 (dense grass)
P= 4.5
L= 175 Elev1= Elev2= Slope= 0.022
T1= 0.007(L *ntts = 0.302 hours= I 18 .1 min
(P)os*(S)o4
Concentrated Flow: V= 2.8 fps (unpaved)
L= 140 Elev1= Elev2= Slope= 0.0300
T1= L/(60*V) = 0.8 min
Gutter Flow 1: V= 2.8 fps (paved)
L= 307 Elev1= Elev2= Slope= 0.0190
T1= L/(60*V) = 1.8 min
Gutter Flow 2: V= 3.45 fps (paved)
L= 158 Elev1= Elev2= Slope= 0.0286
T1= L/(60*V) = 0.8 min
Gutter Flow 3: V= 2.5 fps (paved)
L= 80 Elev1= Elev2= Slope= 0.0150
T1= L/(60*V) = 0.5 min
ITc= 21.2 min
Drainage Area #10
Sheet Flow: n= 0.24 (dense grass)
P= 4.5
L= 125 Elev 1 = Elev 2 = Slope= 0.025
T,= 0.007(L *nl o.s = 0.219 hours=I 13.1 min
(P) o.s *(S) o.4
Concentrated Flow: V= 2.2 fps (unpaved)
L= 300 Elev 1 = Elev 2 = Slope= 0.0190
T,= U(60*V) = 2.3 min
Gutter Flow 1: V= 2.05 fps (paved)
L= 65 Elev 1 = Elev 2 = Slope= 0.0100
T,= U(60*V) = 0.5 min
I Tc= 15.9 min
Drainage Area #12
Sheet Flow: n=
P=
L= 200
T1= 0.007(L *nl o.B =
(P) o.s *(SJ o.4
Concentrated Flow: V=
L= 320
T1= U(60*V) =
Gutter Flow 1: V=
L= 210
T1= U(60*V) =
0.24 (dense grass)
4.5
Elev 1 = Elev 2 =
0.298 hours=._l __ 1_7._9_m_in __ ~
2.8 fps (unpaved)
Elev 1 = Elev 2 =
1.9 min
2.05 fps (paved)
Elev 1 = Elev 2 =
1.7 min
Ir c = 21.5 min
Slope= 0.030
Slope= 0.0300
Slope= 0.0100
.... .._ -.... .._
cu
0.
0 ..-
VI
cu
VI "-::s
0 u "-cu ..... ..,
:JC
3-2
.50
.20 -
.10
.06
.04
. 02 -
.01 -
.005 I
1
J
--~
I
j
7
7
'tf
j
J .
'b q, ,,_ 'b I ~ q, ~ ~, ::::,~ ~'t7 ii
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2
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'
I
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IJ
I
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Average velocity. ft/sec
... .
(2!0-Vl-TR-55. ~cond Ed .. June l98Gl
. , .
' ,
I
I
~
I I
10
, ,
I
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20
APPENDIX B
Storm Sewer Inlet Design Calculations
Castlegate Subdivision
Section 7, Phase 1
Depth of Flow in Street Gutter -Revised 712006
Gutter A c Location {acres)
A1 0.51 0.55 -
A2 1.88 0.55 -·-- - -
A3 0.25 0.55 - -- -
A4 0.46 0.55 ------
B1 1.06 0.55
--------B2 0.10 0.55 ---
C1 1.63 0.55 - --------C2 1.58 0.55 -----------
01 0.89 0.55 ----- -
E1 0.32 0.55 ---------
E2 0.69 0.55 ------E3 0.93 0.55 --------
E4 1.45 0.55 --------ES 2.65 0.55
Transverse (Crown) slope (ft/ft)
27' street = 0.0330
Slope
(ft/ft)
0.0100
0.0184 ----
0.0100 - -
0.01 84 --
0.0150 - -
0.0150 --0.0150 -----0.0150 ----0.01 85 --0.01 20 ----
0.0100 --0.01 20 --
0.0100 ----
0.0100
10-year storm
010 Y10.,.c1ual
(cfs) {ft) {in)
2.42 0.253 3.04 -
9.53 0.378 4.53 ---·--------
1.19 0.194 2.33 ---
2.61 0.233 2.79 ----------
5.03 0.309 3.71 ----------
0.47 0.127 1.53 ---·--------
7.24 0.354 4.25 -------------5.23 0.313 3.76 --· ---------4.23 0.278 3.34 -----------
1.52 0.206 2.47 ----------------3.28 0.284 3.40 -----------4.42 0.307 3.68 --~-------
6.89 0.375 4.50 ---------8.70 0.409 4.91
Straight Crown Flow (Solved to find actual depth of flow in gutter, y):
Q = 0.56 * (z/n) * S112 * y813 ¢ y ={QI [0.56 * (z/n) * S112]}318
n =Roughness Coefficient= 0.018
S = StreeUGutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
z = Reciprocal of crown slope:
27' street = 30
100-year storm
0 100 Y100
{cfs) (ft) {in)
3.26 0.283 3.40
14.67 0.444 5.33 -
1.60 0.217 2.60
5.58 0.309 3.71 --
6.79 0.345 4.15 ---
0.64 0.143 1.71 ----
9.77 0.396 4.75 -----
7.10 0.351 4.22 ---------
5.70 0.311 3.73 -------
2.05 0.230 2.76 ----4.42 0.317 3.81 --
5.95 0.343 4.12 ---9.28 0.419 5.03 -· ---11.83 0.459 5.51
Castlegate Subdivision
Section 7, Phase 1
Inlet Length Calculations -Revised 712006
Inlets In Sump
Inlet# Length & Type Flow from A c a,.
Area# (acres) (els)
I 5· 7 0.32 0.55 1.52 -9 0.69 0.55 3.28
2 10' 8 0.93 0.55 4.42 '5:'5'8 10 1.45 0.55
7 5' 3 0.25 0.55 1.19 ----4 a.46 a.55 2.18
8 1a· 1 0.51 0.55 2.42
2 1.88 0.55 8.93
10 year storm
a.....,,_ a,. .... Orot ... 1Ho y,._ ....
(els) from Inlet# (els) (efs) (ft) (In)
1.52 1.67 0.176 2.11
3.28 3.60 0.235 2.82
4.42 4.86 0.263 3.15
f.63 ff 7.25 7.98 0.317 3.80
1.19 1.31 a.161 1.93
a.co 1a 2.18 2.4a a.2a2 2.42
2.42 2.66 a.21a 2.52
a.77 9 9.70 10.67 0.353 4.24
lnlels On Grade 1 O year storm
Inlet#
9
10
11
Length & Type Flow from y,. a,_ .... a......,
Area# (ft) (In) (ft) (els)
1a· 5 a.354 4.25 0.65 6.47
1a· 6 ci:'3i3-''3}6 a.61 6.07 ~-------10' 11,12 0.409 4.9f 0.70 7.02
Transverse (Crown) slope (fVft) = 0.033
Straight Crown Flow (Solved to find actual depth of flow. y):
a= o.56 • (z/n) ·sin· y"' «> y = (0 t [0.56 • (z/n) • s"W"
n = Roughness Coefficient =
z = Reciprocal of crown slope =
S = StreeVGuller Slope (fVft)
y = Deplh of now al inlet (ft)
Capacity of Inlets on grade:
Oc = 0.7 '[1/(H, • H2)]' [H,~2• H,~2]
Oc = Flow capacity of inlet (cfs)
H, =a+ y
O.Q18
30
H2 =a = gutter depression (2" Standard; 4" Recessed)
y = Depth of now in approach gutter (ft)
a.,,.. .. a_ ..... a. . ..,"_ ~ .......
(els) (efs) (els) ltromlnlet• (els)
a.77 6.47 I 0.77
·0.84 5.23 I a.co
f.63 7.02 I f.63
100 year storm
Lto4t..,.'<111 L11-'ua1 a, .. Oc."Y .. ., a,. .... Orot.t+tn y,,.
(ft) (ft) (efs) (efs)
3.95 5 2.05
4.42
9.61 10 5.95
7.55 4.29
2.78 5 1.80
2.94 a.66
9.98 1a 3.26
12.a3 2.88
"v•tng.,,,,,_•r •o.583'
Ocape-tod C10-r .... 1 y,,.
(els) (els) (ft) (In)
6.47 7.24 a.396 4.75
5.23 5.23 0.351 4.22
7.02 -VO OT59 ~
Inlets In sumps Weir Flow:
L = Q I (3 ' y"2) «> y = (Q I 3L)"'
L = Length of inlel opening (ft)
Q = Flow at Inlet (cfs)
y = lotal depth of now on inlet (ft)
max y for inlet in sump = 7" = 0.583'
from Inlet I (efs) (efs) (ft)
2.05 2.25 0.608 4.42 4.86
5.95 6.55 0.752 ff 11.84 13.02
1.60 1.76 a.526 1a 3.60 3.96
3.26 3.59 0.763 9 14.91 16.40
100 year storm
a,_, ... a......, a.,,.... 0.-..tu""
(ft) (els) (els) (els)
a.69 6.89 2.88 6.89
a.64 6.45 a.66 8.45
-o:75 7'i4 4.29 7.54
(In)
7.30
9.03
6.31
9.16
Oc.,.,.,o.,., °"1,.1otal a_ ... Q100·Tot•I s LKi ... I
(els) from Inlet• (efs) (els) (els) (ft/ft) (ft)
2.88 6.89 9.77 0.015a 1a
0.68 6.45 7.1a a.Q15a 1a ---4.29 7.54 ff.33 O.OfOO fO
APPENDIX C
Storm Sewer Pipe Design Calculations
Castlegate Subdivision
Section 7, Phase 1
Pipe Calculations -Revised 712006
Size Inlet Invert Ele' Outlet Invert
10-year Storm
Contributing Contributing 0 10 Mannings Pipe Length Slope Tc 110 Elev Area Area •Actual Design V10 Tr•v•I Tim•, t119 No. %Full (in) (ft) (%) (ft) (ft) Numbers (acres) (min) (In/hr) (cfs) (els) (fps) (sec)
1 30 156.2 1.00 307.00 305.44 7,8,9,10,11,12 6.04 21 .5 5.97 19.84 7.8 51 .2 ---· ------2 30 56.8 1.50 307.97 307.10 8,10,11,12 5.03 21 .5 5.97 16.52 8.7 41 .1 ------11 24 222.3 1.00 310.75 308.47 11 ,12 2.65 21 .5 5.97 11.34 7.02 6.8 52.3
7 30 153.2 0.50 309.08 308.31 1,2,3,4,5,6 6.31 21 .2 6.02 20.88 6.1 66.1 --8 30 61.1 0.40 309.37 309.13 1,2,5,6 5.60 21 .2 6.02 18.53 5.4 65.8 -9 24 326.3 1.40 314.36 309. 79 5,6 3.21 21 .2 6.02 10.62 17.16 8.5 61.1 -10 18 30.6 1.00 315.17 314.86 6 1.58 21 .2 6.02 5.23 8.44 6.2 71 .8
·r hese values reflect the actual flow for the 18" & 24" pipes. The design flow for these pipe sizes reflects a 25% reduction 1n pipe area.
(Refer to attached calculation for specific information.)
Existing Pipe 15 (30" RCP @ 0.85%)
Information taken from Castlegate, Section 9 Drainage Report:
0 10 = 8.91 cfs
0 100 = 11 .00 cfs
Drainage Area 3A, as shown on Exhibit A:
0 10 = 6.60 cfs
0 100 = 8.90 cfs
When the flow from Pipe 1 is added to the existing storm sewer Pipe 15, then:
0 10 = 8.91 cfs + 19.84 cfs = 28.75 cfs
0 100 = 11.00 cfs + 26.96 cfs = 37.96 cfs
Manning's Data Sheets for Pipe 15 for these two flowrates are included in this appendix.
The existing pipe has adequate capacity.
20
7
33
25
11
38
5
(min)
0.33
0.11
0.54
0.42
0.19
0.64
0.08
100-year Storm
1100 0 100 Mannings
•Actual Design V100 Trevel Time, tlloo •;.Full (In/hr) (els) (cfs) (fps) (sec) (min)
8.12 26.96 8.4 62.1 19 0.31
8.12 22.45 9.4 48.9 ~ 0.10
8.12 12.18 7.54 6.9 54.7 32 0.54 ----1-·--
8.18 28.37 6.2 87.9 25 0.41
8.18 25.18 5.6 86.8 11 0.18 ---8.18 14.43 23.31 9.0 ~ 36 0.60 --8.18 7.10 11.47 6.8 90.7 5 0.08
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 * R213 * S 112
Q =Flow Capacity (cfs)
18" Pipe:
Pipe size (inches)=
Wetted Perimeter W P• (ft) =
Cross-Sectional Area A, (ft2) =
Reduced Area AR, (W) =
Hydraulic Radius R = A/WP· (ft) =
Reduced Hydr Radius RR = AR/WP • (ft) =
Roughness Coefficient n =
Friction Slope of Conduit Sr. (fUft) =
Example Calculation:
Slope Flow Capacity Reduced Flow Capacity
s Q
0.005 6.91
0.006 7.57
0.007 8.18
24" Pipe:
Pipe size (inches)=
Wetted Perimeter WP• (ft) =
Cross-Sectional Area A, (W) =
Reduced Area AR, (W) =
Oreduced
4.28
4.69
5.06
Hydraulic Radius R =A/WP, (ft)=
Reduced Hydr Radius RR= AR/Wp. (ft)=
Roughness Coefficient n =
Friction Slope of Conduit Sr. (fUft) =
Example Calculation:
Slope Flow Capacity Reduced Flow Capacity
s Q Oreduced
0.005 14.89 9.22 ---------·--0.006 16.31 10.1 ·----------------0.007 17.(31 10.9
Conclusion:
18
4.71
1.766
1.325
0.375
0.281
0.014
0.01
% Difference
OreduceiO
0.619
0.619
0.619
24
6.28
3.14
2.355
0.5
0.375
0.014
0.01
% Difference
OreduceiQ
0.619
0.619 --· 0.619
-
Multiply actual Q in 18" & 24" pipes by 1.615 to reflect a 25% reduction in the
cross-sectional area called for on page 4 7, paragraph 5 of the College Station
Drainage Policy & Design Standards manual.
Pipe 1 -10 Year Storm
Manning Pipe Calculato r
Giv en Input Data :
Shape .......................... .
Solving f or .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
19.8400 cfs
0.0100 ft/ft
0 .0140
15 .3684 in
4.9087 ft2
2.5311 ft2
47.8607 in
94 .2478 in
7.8385 fps
7 .6154 in
51 .2278 %
38.0873 cfs
7.7591 fps
Pipe 1 -100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
26 .9600 cfs
0 .0100 ft/ft
0 .0140
18.6331 in
4.9087 ft2
3.2038 ft2
54.4631 in
94.2478 in
8.4150 fps
8 .4708 in
62.1104 %
38.0873 cfs
7.7591 fps
Cast legat e Subdiv i sion -Section 7, Phase 1
College Station, Texas
Revised 7/2006
Pipe 2 -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning ' s n .................... .
Computed Results :
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
16 .5200 cfs
0.0150 ft/ft
0.0140
12 .3315 in
4 .9087 ft2
1 .9014 ft2
41.7584 in
94.2478 in
8 .6884 fps
6.5567 in
41 .1050 %
46 .6473 cfs
9.5029 fps
Pipe 2 -100 Year Storm
Manning Pipe Calc ulator
Given Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning ' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
22.4500 cfs
0.0150 ft/ft
0 .0140
14 .6680 in
4 .9087 ft2
2.3852 ft2
46.4599 in
94.2478 in
9.4122 fps
7.3928 in
48.8934 %
46 .6473 cfs
9.5029 fps
Castlegate Subdivision -Section 7, Phase 1
College Stat ion, Texas
Revised 7/2006
Pipe 11 -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... ·
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
24 .0000 in
11.3400 cfs
0.0100 ft/ft
0.0140
12.5601 in
3.1416 ft2
1.6641 ft2
38.8197 in
75.3982 in
6 .8145 fps
6. 172 9 in
52.3336 %
21.0065 cfs
6.6866 fps
Pipe 11 -100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
24.0000 in
12.1800 cfs
0 .0100 ft/ft
0 . 0140
13. ll80 in
3.1416 ft2
1 .7569 ft2
39 .9384 in
75.3982 in
6.9328 fps
6.3345 in
54 .6584 %
21 .0065 cfs
6.6866 fps
Cas tlegate Subdivision -Sec tion 7 , Phase 1
College St a t ion , Texas
Revised 7/2006
Pipe 7 -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
20.8800 cfs
0 .0050 ft/ft
0. 0140
19.8428 in
4.9087 ft2
3 .4455 ft2
56.9861 in
94.2478 in
6 .0601 fps
8.7065 in
66.1425 %
26.9318 cfs
5.4865 fps
Pipe 7 -100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ..... ." ................. .
Slope .......................... .
Manning's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
28.3700 cfs
0 .0050 ft/ft
0.0140
26.3648 in
4.9087 ft2
4.5703 ft2
72 .9151 in
94 .2478 in
6.2075 fps
9.0259 in
87 .8825 %
26.9318 cfs
5.4865 fps
Castlegate Subdivision -Section 7, Phase 1
Colleg e Station, Texas
Revised 7/2006
Pipe 8 -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
18.5300 cfs
0.0040 ft/ft
0.0140
19.7326 in
4.9087 ft2
3.4237 ft2
56.7536 in
94 .2478 in
5.4122 fps
8 .6869 in
65.7753 %
24.0886 cfs
4.9073 fps
Pipe 8 -100 Year Storm
Manning Pipe Calculator
Given Inpu t Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
We t ted Area .................... .
We t ted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30 .0000 in
25.1800 cfs
0.0040 ft/ft
0. 0140
26.0313 in
4 .9087 ft2
4 .5241 ft2
71.9124 in
94.2478 in
5.5658 fps
9.0592 in
86.7709 %
24.0886 cfs
4.9073 fps
Castlegate Subdivision -Section 7, Phase 1
Col lege Sta t i o n, Texas
Revised 7/2006
Pipe 9 -10 Year Storm
Manning Pipe Calc ulator
Given Input Data :
Shape .......................... .
Solving f o r .................... .
Di ameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning 's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
24 .0000 in
17.1600 cfs
0. 0140 ft/ft
0. 0140
14.6604 in
3 .1416 ft2
2 .0105 ft2
43.0645 in
75.3982 in
8 .5350 fps
6.7229 in
61.0851 %
24 .8552 cfs
7.9117 fps
Pipe 9 -100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full f low velocity ............. .
Circular
Depth of Flow
24.0000 in
23 .3100 cfs
0.0140 ft/ft
0 .0140
18.4522 in
3.1416 ft2
2 .5918 ft2
51.3237 in
75.3982 in
8.9936 fps
7 .2720 in
76 .8843 %
24 .8552 cfs
7.9117 fps
Ca s tlegate Subdivi sion -Sect ion 7, Phase 1
Co llege Station, Texas
Revised 7 /2006
Pipe 10 -10 Year Storm
Manning Pipe Calculator
Given I nput Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning 's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
18.0000 in
8 .4400 cfs
0.0100 ft/ft
0. 0140
12.9278 in
1. 7671 ft2
1.3585 ft2
36.4036 in
56.5487 in
6.2128 fps
5.3737 in
71.8214 %
9.7540 cfs
5.5197 fps
Pipe 10 -100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
18.0000 in
11.4700 cfs
0.0100 ft/ft
0. 0140
16 .3428 in
1 .7671 ft2
1.6857 ft2
45.4504 in
56.5487 in
6.1874 fps
5 .3408 in
90.7933 %
9.7540 cfs
5.5197 fps
Castlegate Subdivi sion -Section 7, Phase 1
Co llege Statio n, Texa s
Reid sed 7 /2006
Existing Pipe 15 -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diamete r ....................... .
Flowrate ....................... .
Slope .......................... .
Manning ' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hy draulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30.0000 in
28 .7500 cfs
0.0085 ft/ft
0.0139
20 .5383 in
4 .9087 ft2
3 .5814 ft2
58.4689 in
94 .2478 in
8.0276 fps
8 .8204 in
68.4608 %
35 .3674 cfs
7 .2050 fps
Existing Pipe 15 -100 Year Storm
Manning Pi pe Calc ulato r
Given Input Data:
Shape .......................... .
Solving f or .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning 's n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full f l ow velocity ............. .
Circular
Depth of Flow
30.0000 in
37.9600 cfs
0 .0085 ft/ft
0 . 0140
27.6031 in
4 .9087 ft2
4.7251 ft2
77.0539 in
94.2478 in
8.0337 fps
8 .8304 in
92.0104 %
35.3674 cfs
7.2050 fps
Castleg ate Subdivision -Section 7, Ph ase 1
College Station, Texas
Revised 7/2006
EXHIBIT A
Post-Development Drainage Area Map
27
* C1vIL DEVELOPMENT, Lta.*
Date:
To:
From:
Subj ect:
Remarks:
CIVIL ENGINEERING & DESIGN-BUILD SERVICES
TRANSMITTAL
July 28, 2006
Carol Cotter
Development Services
City of College Station
Joe Schultz, P.E.~
Civil Developme;f Ltd.
P.O. Box 11929
College Station, Texas 77842
Phone: (979) 764-7743
Construction Drawings
Castlegate Subdivision, Section 7
College Station, Texas
Accompanying this transmittal are the following documents
• 1 set of sealed construction drawings for your review (others wi II
follow if revisions are approved)
• one copy ofresponses to City Comments
• two copies of the revised construction estimate
• two copies of the revised Drainage Report
• two copies of the Water and Sewer Report
Castlegate Subdivision, Section 7
Final Plat
Res ponse to Engineering Co mments No. 2
1. Your drainage report certifies that there will not be any impact on properties downstream of the
Crowley Tract resulting from this development. Are you also certifying that there is no impact
downstream of Section 7?
Response: The Castlegate development downstream of Section 7 was designed assuming full
development of all sections of Castlegate. Greenbelt areas were left along the tributaries of
Spring Creek through Castlegate so that the 100-year floodplain limits were almost totally within
these areas. Also, the existing pond located in Section 7 provides detention for the Castlegate
Subdivision. Construction of Section 7 will have no downstream impact.
2. Is the runoff coefficient of 0.5 adequate? The previous report for Section 7 used 0.5, but the
development was for a less dense residential development.
Response: The runoff coefficient was changed to C=0.55. The revised results are included in the
revised drainage report.
3. Page 3 of the Drainage Report states that the runoff flows into a proposed regional detention
facility. I'm assuming you mean the existing one.
Response: It is the existing detention facility. Page 3 was revised in the report.
4. Pl ease show in the plans the grading req uired to keep the 100-year storm within the ROW.
Response: A Grading Plan (Sheet 4A) has been added.
5. What is the size of the existing storm pipe into which Pipe 1 is discharging? Is there capacity?
Response: The existing pipe is 30 " in diameter. Calculations have been added to the drainage
report to show this pipe is adequate.
6. The drainage from off-site onto Stone Castle Circle and from Stone Castle Circle off-site needs to
ensure that there is no unde1m ining of the roadway. Please address.
Response: Rock rip-rap has been placed at the end of streets to prevent undermining (Sheets 3 &
4).
7. The manhole lids in the pavement near the storm inlets shall be watertight.
Response: Lids for Manholes 2 & 5 have been specified as watertight on Sheet 10.
8. Are yo u able to center a joint of pipe (min 18') over the sewer line at Sta 0+15 , Sheet 6? How are
you planning to meet TCEQ requirements at this location?
Response: The water line design has been revised so that a joint of pipe is centered over the
sewer line.
9. Plan view ca lls out 8x6 tee at Sta 3+20 .35. Profile shows 8x8. (Sheet 6)
Response: The plan view has been revised.
Castlegate, Section 7
Res ponse tn Eng ineering Comments o. 2
l)agc I of 2
10. The sewer (and future water) line crossings under the high pressure gas li ne may need additional
protection (encasement). Please provide documentation from Citgo with their requirements for
these crossings. (Sheets 9 & 11)
Response: We met with the Citgo Field Representative and were told th eir requirements for
sewer and water crossings are:
• PVC pipe only at the crossing -do ductile iron
• Minimum of 2 ' of clearance
No written documentation was given for these requirements.
In order to meet Ctigo 's requirement of 38" of clearance for the street in Phase 2, the profile of
Stone Castle Circle has been revised as shown in the plans. This revision resulted in the addition
of another storm sewer inlet and storm sewer pipe.
11. Show conflicts with gas line crossings.
Response: Gas line crossings have been shown.
12. Submit water and sewer design reports.
Response: Water and Sewer Reports are included with this submittal.
Castlega te. Section 7
Response to Engineering Comments No. 2
!'age~ or 2
Item
I
2
3
4
5 --
6
7
8
Castlegate Subdivision, Phase 7
Revised Engineer's Estimate
July 28, 2006
Description I Unit
Estimated
uantit
Sitework & Pavement -·-·------------------. --Mobilization/Construction Staking LS 1
Clearing & Grubbing (w/onsite burning) AC 5.9
Excavation (est. cut= 2354 cy., est. fill = 164 cy) I LS 11
6" Lime Stabilization (6% lime by weight) I SY 7,579 j
6" Crushed Limestone Base I SY _2,_8 .!21 ---~ -----2" Hot Mix Asphaltic Concrete SY 5,817
Curb & Gutter (all types) LF 3,979
Concrete apron SF 4,1181
Unit Price
6,000.00
3,000.00
14,200.00 ~
3.60
8.QQ;
7 50 1
8:501
5.50
Sitework and Pavi ng Subtotal!
Drainage ----~---311 --30.0~ 9 18" HDPE Pipe, structural backfill
10 24" HDPE Pipe, structural backfill ' LF 601 35.001
11 30" HDPE Pipe, structural backfill
I
LF 61 1 55.001
12 30" HDPE Pipe, non-structural backfill LF 30~1 47.00
13 1 O' Recessed Inlet EA 3,200.00
----T--I 14 5' Recessed Inlet EA 3,000.00
15 Concrete Headwall for 30" HDPE Pipe I EA 1 2,800.00
16 Connect to junction box I EA 1 2,500.001
17 Silt Fence
_l ~~ --~------~~40~! ____
2.75
18 Inlet Protection 125 .ool --------..._ --19 Construction Exit ' EA 1 1,500.00!
20 Rock Rip Rap
I
SY 36 55.00
21 Hydromulch Seeding (back of curb to ROW) SY 5,290 0.60
22 SWPPP Implementation & Maintenance LS 1 2,500.00
23 TV Ins2ection ' I LF 1,002 3.50
Drainage Subtotal[
Water
24 6" C909 Water Pipe, structural backfill i LF -381-
25 6" C909 Water Pipe, non-structural backfill 1 LF I 695 1
26 8" C909 Water Pipe, structural backfill I LF 196
27 8" C909 Water Pipe, non-structural backfill I LF ~-1,22 1
28 Fire Hydrant Assembly (w/ 8"x 6" tee, valve, vert. extension) EA I
29 Fire Hydrant Assembly (w/ 6"x 6" tee, valve, vert. extension) I EA 1
30 8" M.J. Gate Valve I EA 31
31 6" M.J. Gate Valve EA 3
32 8"x 8" M.J. Tee EA 1 I
33 8"x 6" M.J. Tee -----· ----------· ·--34 6"x 6" M.J. Tee
35 8" x 45° M.J. Bend
36 8" x 22.5° M.J. Bend
37 8" x 11.25° M.J. Bend
38 6" x 45° M.J . Bend
39 6" x 22.5° M.J. Bend
40 6" x 11.25° M.J. Bend
4 1 8" x 6" M.J. Reducer
42 Conn ec t to existing water line
43 2" Blow Off Assembl y
l'agL· I u( 2
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
I
6
2
I
2
·--··--t
26.00
22.00
30.00:
26.00 1
--2,600.00
2,400.00
850.00
550.00
375.00
350.00
-
300.00
300.00
300.00
300.00
250.00
250.00
250.00
375.00
500.00
750.00
Total
6,000
17,550
14,200
27,284
46,536
43,628
33,822
22,649
$2 11 ,668
930
21,035
3,355
14,523
16,000
6,000
2,800
2,500
3,853
875 ----
1,500
1,980
3,174
2,500
3,507
$84,532
988
15,290
5,880
31 ,746
2,_600
2,400
2,550
1,650
375
350
300
1,800
600
300
250
250
250
375
500
1.500
Item I
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
Castlegate Subdivision, Phase 7
Revised Engineer's Estimate
July 28, 2006
Description Unit Estimated I 1
Unit Price Quantity
1.5'' Water Service '.S 15 ft (avg. length = 3 ft) I EA I 81 900.001
1.5" Water Service > 15 ft (avg. length = 49 ft) I EA 11 1,200.00
l" Water Service '.S 15 ft (avg. length = l 0 ft)
I
EA 3 700.001
l" Water Service > 15 ft (avg. length = 44 ft) EA l 1,000.001
Water Subtotal I
Sewer -----6" PVC Sewer Line, 03034, SDR 26, structural backfill LF 444 30.00
6" PVC Sewer Line, 03034, SDR 26, non structural backfill LF 642 26.00
6" PVC Sewer Line, 02241, SDR 26, structural backfill LF 20 33.00
8" PVC Sewer Line, 03034, SDR 26, structural backfill LF 326 55.00
8" PVC Sewer Line, 03034, SDR 26, non structural backfill LF 886 40.00
8" PVC Sewer Line, 02241, SDR 26, non structural backfill LF 20 43 .00
Standard 4' Manhole, 0-8.00 ft depth EA 2 2,600.00
Standard 4' Manhole, 8.01-10.00 ft depth EA 6 2,900.00
Standard 4' Manhole, 14.01-16.00 ft depth, on existing 12" lirn EA 1 3,800.00
6' Drop Structure for 8" sewer line EA 1 1,000.00
6" PVC Cap EA 2 100.00
TV Inspection LF 2,338 3.50
4" Sewer Service '.S 15 ft (avg. length = 4 ft) EA 14 500.001
4" Sewer Service > 15 ft ~avg. length = 39 ft) EA 12 900.00
Sewer Subtotal!
TOT AL CONSTRUCTION I
Total
7,200
13,200
2,100
1,000
$93,454
--· --13,320
16,692
660
17,930
35,440 -860
5,200
17,400
3,800
1,000
200
8,183
7,000
10,800
$138,485
$528,139
Water and Sewer System Report
for
Castlegate Subdivision, Phase 7
College Station, Texas
July 2006
Prepared B y:
Civil Development, Ltd.
2900 Longmire Drive, Suite K
College Station, Texas 77845
(979) 764-7743
General Information
Location:
General Note:
Land Use:
Design Criteria
Castlegate Subdivision, Phase 7 is located immediately south of Phase 8 and west of
Phase 6 in southern College Station.
Phase 7 contains 30 platted lots, but there are an additional 17 lots in a future phase
adjacent to it that will be served by the same water and sewer lines. These
additional lots have been taken into account in this analysis of the water and sewer
systems.
Single Family Residential
WATER SYSTEM ANALYSIS
Primary Water Supply: Existing 12" line along Castlegate Drive.
Domestic Demand:
Avg. Pop Density:
Average Flow:
Peaking Factor:
Peak Flow:
Design Flow:
Fire Demand:
Fire Flow:
Pipe:
Roughness Coeff:
Hydraulic Software:
2.67 people per lot
100 gpd/cap or 267 gpd per lot= 0.18 gpm per lot
4
0.74 gpm per lot
1.50 gpm per lot
1000 gpm at most hydraulically remote point
PVC DR-14 C909
150 (Hazen Williams)
Haestad Methods WaterCAD v.6.0
Existing City System Pressure Tests
Flow Hydrant #: V-035
Flowrate: 1140 gpm
Adj. Hydrant #: V-036
Static Pressure: 90 psi (208 ft water)
Residual Pressure: 85 psi (196 ft water)
Applicable Exhibits: Exhibit A -College Station Utilities Flow Test Report
Water System Analysis Summary
Criteria Required As Location Designed
Min. Pressure -fire (psi) 20 73 C7 FH2
Max. Velocity (fps) 12 6.82 P-1
Max. Le11gth of 6" pipe (ft) 1500 700 (connected to~ 8 "on both
Max Length of 6" pipe (ft) 800 25 (no t connected on both e11ds
Max. Length of 3 "pipe (ft) 500 NA
Applicable Exhibits: Exhibit B -Water System Schematic
Conclusion
Design Criteria:
Exhibit C -Junction Summary -Static & Fire Flow Conditions
Exhibit D -Pipe Summary -Fire Flow Conditions
The proposed water system for Castlegate Subdivision, Phase 7 meets or exceeds all
of the design criteria for the City of College Station. It will provide adequate water
pressure and flow for both domestic and fire demands.
SEWER SYSTEM ANALYSIS
Primary Sewer Outfall: Existing 12" sewer line in Castlegate Drive
Domestic Demand:
Avg. Pop Density:
Average Flow:
Peaking Factor:
Pipe:
Applicable Exhibits:
Conclusion:
2.67 people per lot
100 gpd/cap or 267 gpd per lot
4
PVC D3034 SDR 26
Exhibit E -Sewer System Schematic
Exhibit F -Sanitary Sewer Analysis Spreadsheet
As indicated on the spreadsheet, the sewer system for Castlegate Subdivision, Phase
7 easily meets all of the design criteria and requirements of TCEQ and the City of
College Station. If will easily serve all of the lots in this subdivision, as well as the
future lots that will share the system.
1601 GRAHAM ROAD
COLLEGE STATION TEXAS 77845
Date: 4 MARCH 2004
Nwnber pages including cover sheet - 1
Fax to: 764-7759
Attention: JOESCHULTZ
Company: TEXCON
From: Butch Willis Water Wastewater Division
Phone: 979-764-3435 Fax: 979-764-3452
FLOW TEST REPORT
Location: CASTLEGATE DRIVE
Flow hydrant number: V .:.035
Pitot reading: 80
(GPM): 1140
. , ·-'>.Static hydrllllt nUmber: . V-036 .
.·-" , -
-{~·~ ... ~ .:. ..
. J ·.: ·~ ?. ··s• .. ~t--• .......
~001
Exhibit A
i . ,,;~~-·~~~i1l~~i,?;!1;,:~·:, .. ,).i,c;~~~.,,; .. ::~:~~~'. _;,. ;.;.: ?:< .; . : ~;l~~-:i:~t'. : .
~':. '"~ .
-,-.:~:~ ••.. .-,.-.· -< -~ . '• ..
\ \}~: .•:.'.·'.'._·< . ? ..
. :.· . . . ·.·:
Exhibit B
Water System Schematic
1 ested Hydrant
C8 01 -··--·--P-10 ...----·..B -----1~-U-----.... ..----
Cast\egate Drive
' 7 -1---\
2 : BLOCK \ ,~ _\ , I
/ I
,' \
.l
C7 F\-1 I
I
--_i _j . ! ' ! ' ! !, r r-1r---1--1·-lliOCKJ
I 9 I I --
' Ill I r-1 \\ / , \2 \ 3
"-.c: Q
~ (1J
O> <I> :;:;
Cl)
(1J 0
Exhibit C
Castlegate Subdivision, Phase 7
Water System Analysis
Junction Summary
Static Flow Conditions
Label Elevation j Demand I Hydraulic Grade I Pressure
(ft) (gpm) (ft) (psi)
C7 01 317 1a 519.22 a7.49
C7 02 317 3 519.22 a7.49
C7 03 321 15 519.22 a5.76
C7 05 321 6 519.21 a5.76
C7 FH1 316 0 519.23 a7.93
C7 FH2 324 27 519.21 84.46
''··" ...
ca 01 312 0 519.27 a9.67
Tot. Static Demand: 69
Lowest Pressure in Subdivision Phase (Static): 84.46
Fire Flow Conditions
C7 01 317 18 499.41 7a.92
C702 317 3 499.41 7a.92
C7 03 321 15 499.39 77.18
C705 321 6 499.39 77.18
C7 FH1 316 0 501.75 80.36
C7 FH2 324 1027 493.60 73.3a
ca 01 312 0 507.50 a4.59
Tot. Fire Demand: 1069
Lowest Pressure in Subdivision Phase (Fire): 73.38
Label
P-1
P-2
P-4
P-5
P-6
P-8
P-9
P-1 0
Exhibit D
Castlegate Subdivision, Phase 7
Water System Analysis
Pipe Summary
Fire Flow Conditions
Length . __ Diameter Material Hazen-Discharge
(ft) (in) Williams (gpm)
363 8.0 PVC 150 1,069
534 8.0 PVC 150 534
536 8.0 PVC 150 -535
31 6.0 PVC 150 3
54 6.0 PVC 150 6
352 6.0 PVC 150 513
348 6.0 PVC 150 -514
555 12.0 PVC 150 -1,069
Velocity
(ft/s)
6.82
3.41
3.42
0.03
0.07
5.82
5.84
3.03
Highest Pipe Velocity: 6.82
---~,~ --..... --.... , --.. .,
Exn.1b·1t E
system scnernotic
C7 f
Cast\egate Drive
tt __ ... ,,-
I
I -------·'\
I
I
-~,\
Lin~
.9 :i: !!! " 0 E 0 "O u: "' ..J 0 " ~ z " 0/) !::: "'
r10111 To f= "O ·§ :3-~ 5 -0 2Z "O "-:"§ E z ·;;; :: c: 0 " 0:: 0 0 <!:: u: u
267
GPD per
VIH # MH# Lot GPD
!lutfall #I -. -( ·7 ;\ C7 B 18 4,806 --C7 B C7E 8 2,136 4,806
( ·7 c C7 D 9 2.403 -·-C7 D C7 E ' 12 3,204 2,403 -I «7 E C7 F 0 -5,607 ------
-
-
Exhibit F
Castlegate Subdivision, Phase 7
Sanitary Sewer Analysis
July 3, 2006
Flow Calculations
Manning Min.
Average Daily Infiltration Peaking Inside Friction Design Peak Size Material Flows (ADF) (10%ADF) Diameter Slope Slope Factor Flows
ADF ADF
I
GPD I CFS CFS CFS (in.) Inches % %
4,806 0.0074 0.0007 4.00 0.03 6 D3034 5.793 0.0010 0.80
6,942 0.0107 0.0011 4.00 0.04 8 D3034 7.754 0.0004 0.40
2,403 0.0037 0.0004 4.00 0.02 6 D3034 5.793 0.0003 0.80
5,607 0.0087 0.0009 4.00 0.04 8 D3034 7.754 0.0003 0.40
5,607 0.0087 0.0009 4.00 0.04 8 D3034 7.754 0.0003 0.40
Pipe Calculations
Actual Manning Min. Slope for Ave. Daily Ave. Daily Friction Design Pipe Peak Peak Existing Flow Flow Slope Slope Slope Flow Flow or Velocity Depth Peak Peak Check Velocity Depth Designed Flows Flows I Systems
I I I I I
I
I I fps Inches % % % fps Inches
I
I
0.95 0.29 0.0035 0.80 0.80 OK 1.37 I 0.87
0.78 0.39 0.0016 0.40 0.40 OK 1.18 1.16
0.74 0.00 0.0009 0.80 0.80 OK 1.12 I 0.58
0.74 0.00 0.0010 0.40 0.40 OK 1.12 1.16
0.74 0.00 0.0010 0.40 0.40 OK 1.12 1.16
---I I I I I