HomeMy WebLinkAbout51 South Hampton Ph 3 04-22Drainage Report
for
South Hampton Subdivision
Phase 3
College Station, Texas
May 2004
Revised July 2004
Deve loper:
Nantucket, Ltd.
1101 University Drive East, Suite 10 8
Co llege Station, Texas 778 40
Prepared B y :
TEXCON Genera l Contractors
1707 Graham Ro a d
Co llege Station , Te as 77845
(979) 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 Phase 3 of the South Hampton Subdivision in College
Station, Texas, was prepared by me in accordance with the provisions of the City of College Station
Drainage Policy and Design Standards for the owners hereof, with the exception that storm water
runoff detention is not being required for this project since it was detennined during the development
of Phase l of the subdivision that the site discharges directly into the TxDOT storm drainage system ,
which discharges into a tributary of Alum Creek . This tributary is a part of the Alum Creek primary
system, which is a part of the Lick Creek drainage basin. Nantucket Lake serves as a detention facility
for the Alum Creek drainage basin, and with the South Hampton runoff discharging into this primary
system downstream of the lake, the South Hampton peak runoff will have already passed before the
peak discharge at Alum Creek, therefore resulting in no increase in the peak runoff in Alum Creek.
TABLE OF CONTENTS
SOUTH HAMPTON SUBDIVISION -PHASE 3
Revised July 2004
CERTIFICATION .................................................................................................................................................................. 1
TABLE OF CONTENTS ........................................................................................................................................................ 2
LIST OF TABLES .................................................................................................................................................................. 2
INTRODUCTION ................................................................................................................................................................... 3
GENERAL LOCATION AND DESCRIPTION .................................................................................................................. 3
FLOOD HAZARD INFORMATION .................................................................................................................................... 3
DEVELOPMENT DRAINAGE P ATTERNS ....................................................................................................................... 3
DRAINAGE DESIGN CRITERIA ........................................................................................................................................ 3
STORM WATER RUNOFF DETERMINATION ............................................................................................................... 6
STORM SEWER DESIGN .................................................................................................................................................... 6
STORM WATER DETENTION ........................................................................................................................................... 7
CONCLUSIONS ..................................................................................................................................................................... 7
APPENDIX A .......................................................................................................................................................................... 8
Time of Concentratio1t Data & Calculations (Revised)
APPENDIX B ........................................................................................................................................................................ 12
Storm Inlet Design Data & Calculatio1ts (Revised)
APPENDIX C ........................................................................................................................................................................ 15
Storm Pipe Design Data & Calculations (Revised)
EXHIBIT A ............................................................................................................................................................................ 22
Post-Development Drainage Area Map (Revised)
LIST OFT ABLES
TABLE 1 -Rainfall Intensity & Runoff Data .................................................................................................... 5
TABLE 2 -Time of Concentration (tc) Equations ............................................................................................. 5
TABLE 3 -Post-Development Drainage Data -Revised ........ : .......................................................................... 6
DRAIN AGE REPORT
SOUTH HAMPTON SUBDIVISION -PHASE 3
R evis ed July 2004
INTRODUCTION
The purpose of this revised repoti is to provide the hydrological effects of the construction of
Phase 3 of the South Hampton Subdivision , and to show that the sto nn water runoff wil l be
controlled in suc h a manner so as to h ave minimal offsite or downstream impact .
GENERAL LOCATION AND DESCRIPTION
The project is located on a 4 acre tract loc ated in College Station, Texas . The site is wooded
with areas of open land with grass. The existing ground elevations range from elevation 261 to
elevation 273. 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 Alum Creek Drainage Basin, which is a part of the Lick Creek
Drainage Basin. No portion of the site is located in a Special Flood Hazard Area according to
the Flood Insurance Rate Map (FIRM) prepared by the Federal Emergency Management
Agency for Brazos County, Texas and incorporated areas dated Febmary 9 , 2000, panel
number 48041C0205-D .
DEVELOPMENT DRAINAGE PATTERNS
Prior to development , storm water runoff from the site generally flows in a notiherly direction.
A majority of the runoff flows into an existing concrete flum e and then into the existing storm
system, which ties into the stom1 drainage system in the State Highway 6 right-of-way. A
small portion of the runoff flows in a northwesterl y direction where it enters th e Nantucket
Drive right-of-way. After development, these flow patterns will typically remain the same,
however, the water captured by the existing flume wi ll be diverted through the proposed stom1
system, which ties into an e.,'l;isting storm drain inlet before discharging into th e storm drainage
system . This system ultimately discharges into Alum Creek . The post-development drainage
area boundaries are shown on Ex hibit A.
DRAINAGE DESIGN CRITERIA
The design parameters for the stom1 sewer are as follows:
• The Rational Method is utili zed to determin e pea k stom1 water run off rate s for the
storm sewe r desi g n .
• Desi gn Stonn Frequency
Storm sewe r sys tem
• Run off Coe ffi c ient s
Single Family R es id enti a l
Undeveloped
I 0 a nd I 00-year sto rm eve nt s
c = 0.50
c = 0.30
• Rain fa ll Int e ns it y equati o ns a nd va lu es for Bra zos Co unt y ca n be found in Ta bl e I.
• Time of Concentration, tc -Calculations are b ased 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 calcu lating the times of concentration are shown in Ex hibit
A. For smaller drainage areas , a minimum tc of 10 minutes is used to detennine th e
rainfall intensity values.
TABLE 1 -Rainfall Intensity & Runoff Data
Rainfall Intensity Values
(in/hr)
Storm
Event
Is
'10
bs
lso
1100
Brazos
County:
tc =
10 min
7.693
8.635
9.861
11.148
11 .639
I = b I (tc+d)e
I = Rainfall Intens ity (in/hr)
tc = U(V*60)
le = Time of concentrat io n (min)
L = Length (ft)
V = Vel ocity (ft/sec)
5 }::'.ea r storm 10 }::'.ear storm 25 }::'.ear storm 50 }::'.ear storm 100 }::'.ear 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 .76 3 e = 0 .754 e= 0.745 e= 0.730
(Data taken from State Department of Highwa}::'.s and Public Transportation H}::'.drau lic Manual, page 2-16)
TABLE 2 -Time of Concentration (tc) Equation s
Th e tim e of concentration was d etermined using methods found in TR-55, "Urban
Hydrology for Small Watersh eds." The equations are as follows :
Time of Concentration:
For Sheet Flow:
Tc= T1{sheet n ow)+ T1{concentrated sheet n ow)
where: T 1 =Travel Time, minute s
0.007 (n L)°-8
(Pz)o.s s0.4 where: T 1 = travel time , hours
n =Mannin g's roughness coeffic ie nt
L = flow length , feet
P2 = 2-year, 24-hour ra in fall = 4 .5"
s = land s lope, ft /ft
For S ha llow Concentrated Flow: T 1 =LI (60 *V)
R e fe r to Appendi x A for ca lc ul atio ns.
where : T 1 =travel time , minute s
V =Velocity, fps (See Fi g 3-1, App. E)
L = flo w le ngth , feet
STORM WATER RUNOFF DET E RMINATION
The peak runoff valu es were determined in accord ance with the crit eria presented in th e
previous sectio n fo r the 5 , l 0 , 25, 50, and 100-year storm events . The runoff co e ffic ie nts
for post-development ca lcul at ions are based on the fut ure d evelop m e nt of this tract , a nd th e
peak runo ff va lu es d etermin ed for the post-deve lopment condition a re shown in Tab le 3 .
TABLE 3 -Post-Development Drainage Data -R evised
Are a t c
5 year storm 10 year storm 25 year storm 50 year storm 100 yea r storm
Area# c Is O s 110 010 l2s 0 2s lso O so 1100 0 100
(acres ) (min) (in/hr) (cfs) (in /hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in /hr) (cfs)
1 3.65 0 .50 13.4 6 .739 12 .30 7 .592 13.85 8 .684 15.85 9.831 17 .94 10 .258 18 .72
2 1.14 0 .50 10.8 7.441 4.24 8.360 4.77 9 .552 5.44 10.802 6 .1 6 11 .276 6.43
3 0 .58 0 .50 10 7 .693 2.2 3 8.635 2.50 9 .86 1 2 .86 11.148 3 .23 11 .639 3.38 -----
4 0.52 0.50 10 7 .693 2 .00 8.635 2.24 9 .86 1 2 .56 11.148 2 .90 11 .639 3 .03
5 0.41 0.50 10 7.693 1.58 8 .635 1.77 9 .86 1 2 .02 11 .148 2.29 11 .639 2 .39
6A 3 .35 0.50 27 .0 4 .612 7.73 5 .251 8.80 6 .033 10 .10 6.860 11.49 7.163 12 .00
68 0 .26 0.50 10 7.693 1.00 8 .635 1.12 9.86 1 1.28 11 .148 1.45 11 .639 1.51
The post-development drainage areas are shown on Exhibit A. Even though th e runoff
coefficient for the d evelop ed conditions increases the runo ff, the stom1 sewer s ystem
conveys the runoff directly to a tributary of Alum Creek.
STORM SEWER DESIGN
The stonn sewer pip ing for this project h as b een selected to be Reinforced Concre te Pip e
(RCP) m eeting the requ~rements of ASTM C-76, Class III p ipe . T h e curb inlets wi ll be
cast-in-place co ncrete. Appendix B presents a summary of the storm sewer inlet desi gn
parameters and calculations . T h e inlets were d esigned b ased on a 10 -year desi g n storn1 .
As per College Station g uid e lin es, the capacities of inle ts in sump were reduced by l 0 % to
allow for clogging.
In le ts were located to maintain a g utter flow d epth of 5" or less, w hich will pre ve nt th e
spread of water from reaching th e crown of the road for the 10-year stom1 event. Refer to
Appendix B fo r a summary of the g utter flow depths at various locations. The runoff
intercepted by the proposed storm sewer inlets was calc ul ated using the following
equations . The depth of flow in the g ut te r was det e rmined by us ing the Strai g ht C rown
Flow equation . T he flows intercepted by In lets 1 & 2 were calcul ated by using th e
Capacity ofln lets On Grade equat ion . These equations and th e resultin g data a r e
summari zed in App e ndix B . There a r e no proposed inlets in s ump for th is ph ase of th e
d eve lopme nt. T h e are a b e tw e en the right-of-wa y and the curb line of the s tree ts w ill be
filled as nece s sary to provid e a minimum of 6" of fre e board above the c urb lin e . Thi s w ill
e nsure th a t th e runoff from th e 100-year storn1 ev e nt w ill re ma in w ith in th e s tr ee t ri g ht-of-
w ay.
A pp e ndi x C prese nt s a s ummary o r th e s torm sewe r p ipe d es ig n param e te rs a nd
ca lc u lati o ns. A ll pip es a re 18" in di a m e te r or lar ge r. T h e pip es for th e s to r m se we r sys te m
w e re d es ig n ed ba sed o n th e 10 -yea r s torm event ; ho wev e r, a ll w ill a lso pa ss th e I 00-ycar
s to rm event w ithout a n y he a dw a te r . As re q uire d b y C o ll ege S ta tion , th e ve loc it y o r !l ow in
th e s to rm s e we r p ipe sys te m is no t lowe r t han 2.5 ree l pe r se co nd , and it docs no t ex ce e d
15 ree l pe r seco nd . As th e cl ;1ta s how s, eve n durin g low ll o\\· c o ncliti o n s, th e \Cloc it y in the
(l
pip es will exceed 2.5 feet pe r second and prevent sed im e nt build-up in the pip es . Th e
m ax imum flow in the storm sewer pip e system wil l occ ur in Pip es lA & lB. App end ix C
conta in s a summary of the Manning pip e calc ul ati ons fo r th e storm sewer system for the I 0
and 100-year eve nt s. The maximum ve lo city for the pipe system w ill be 9.8 feet pe r
seco nd and wi ll occur in Pipes lA & 1 B . The storm sewer system frolll Cranb erry Drive
to Windrift Cov e will be located in a 15' public drainage easement. The storm sewer
pipe system passes th e 100-year storm event runoff, therefore, 110 overland flow is
proposed for the drainage easement. Th e headwater for Pip e No. 3 is elevation 263.43
for the 100-year stor/ll event. The propose d top oft!t e street is elevation 264.50, as is th e
adjacent top of slope of the e..x:isting drainage chmwel. Th erefore, the runoff in th e
e..-ds ting channel upstream of Cranberry Drive will be contained within th e drainage
easement.
The storm sewer pipe system discharges into an existing storm drain inlet. This inlet is a
10' inlet in a sump, and the gutter depth at this inlet is 5.28"for the JO-year sto rm event,
and 5.88"for the 100-year storm event. The existing 24" pipe and h ea dwall and th e
co ncrete flume, which collect the runoff from an e..x:i stin g drainage ditch and discharge
into the e..x:isting storm inlet, will be removed and replaced with the proposed storm sewer
piping. The existing ditch. will be filled to drain as shown on th e construction drawin gs.
STORM WATER DETENTION
The storm water runoff detention is not bei ng required for this project since it was
determi ned during the development of Phase l of the su bdi visio n th at the site discharges
direct ly into the TxDOT storm drainage system, which dis charges into a tributary of A lum
Creek . This tributary is a part of the Alum C reek primary system, which is a part of th e
Lick Creek drainage basin. Nantucket Lake serv es as a detention facility for the Alum
Creek drainage basin, and with the South Hampton runoff discharging into thi s primary
system downstream of the lake, the South Hampto n peak runoff wi ll h ave a lready pass ed
before the peak discharge at Alum C reek, therefore res ulting in no increase in the peak
runoff in Alum Creek.
CONCLUSIONS
The construction of this project will increase th e storm water runoff from this si te;
ho wever, it should not have a significant impact on the s u1Totmdin g property. No flood
damage to downstream or adjacent landow ners is ex pected as a res ult of this d eve lop m ent.
APPENDIX A
Time of Concentration Data & Calculations (Revised)
Time of Concentration Calculations
Refer to Exhibit A for flow paths used for calculations.
Drainage Area #1:
Sheet Flow: Flow length = 125' = L
Slope= 3 .7%
n = 0.15, short grass , prairie
P 2 = 4 .5"
ti=0 .007(0 .15*125)0 8
(4.5)05 (0 .037)04
ti = 0.129 hours= 7.7 minutes
Shallow Concentrated Flow: Flow length = 535' = L
Slope= 2.1%
Flume Flow:
Drainage Area #2:
Sheet Flow:
For unpaved surface at 2.1 %, Velocity (V) = 2 .3 fps (see Fig. 3-1)
~ ti= 535' I (60 *2.3) = 3.9 minutes
Flow length= 355' = L
Slope= 2 .7%
For paved surface at 2 . 7%, Velocity (V) = 3 .3 fps (see Fig. 3-1)
ti= 355' I (60*3.3) = 1.8 minutes
Tc= 7.7 + 3 .9 + 1.8 = 13.4 minutes
Flow length = 125' = L
Slope= 3.1 %
n = 0.15 , short grass, prairie
P2 = 4.5"
ti= 0 .007 (0.15 * 125)08
(4.5)0·5 (0 .031)04
ti = 0.138 hours = 8 .3 minutes
Shallow Concentrated Flow: Flow length = 195' = L
Slope = 1.8 %
Fluine F lo w:
For unpaved surface at 1.8 %, Velocity (V) = 2.15 fps (see Fig . 3-1)
ti = 195 ' I (60 *2 . l 5) = 1.5 minute s
Flow len gth= 200' = L
Slope = 2.7 %
For paved s urface at 2.7%, Veloc it y (V) = 3.3 fp s (see Fig. 3-1)
ti= 200' I (60*3 .3) = 1.0 minutes
Tc= 8.3 + 1.5 + 1.0 = 10.8 minutes
Time of Concentration Calculations, continued
(R evised July 2 004)
R ef er to Exhibit A fo r flow p at hs us ed for ca lcula ti on s .
Dra inage A re a #6A :
Sh ee t Flo w:
Pa vement Flow:
F low le ngth = 2 15' = L
S lope = 3 .0 %
n = 0.24 , den se grass
P2 = 4 .5"
t( = 0.00 7 (0 .24 * 2 15)0 8
(4 .5)05 (0 .0 3)0 4
t1 = 0 .3 15 ho urs = 18.9 min utes
F lo w len gth= 6 8 ' = L
S lope = 1.23 %
For paved s urface a t 1.23 %, V eloc ity (V) = 2 .2 fp s (see Fi g. 3-1)
t1 = 6 8' I (60 *2 .2) = 0.5 minutes
Si mi larl y:
L = 23 7 ', S = 2%, V = 2 .85 fps , t1 = 1.4 minutes
L = 2 17', S = 3%, V = 3 .6 fp s, t1 = 1.0 m inu tes
L = 50 3 ', S = 6%, V = 1.6 fps , t1 = 5 .2 min utes
Slope = 2 .7%
T c= 18 .9 + 0 .5 + 1.4 + 1.0 + 5 .2 = 27.0 minutes
+-' <+--+-' <+-
GJ a.
0
r-
"'
GJ
"' '-::::s
0 u
'-GJ .., .,
3:
3-2
.50
.20 -
.10
.06
.04
.02 -
.01 -
.005
' 1
j
I
·-·
j
I
) I
. ,
j ,
).
0
::..q, ),_bl
~ -q, ::::,~ c/1
J
I
j
I
I
j
I
2
.
.
f
J
'
' 4
I
J
I
J
)
I
..
I
6
'
I
'j
' I
Av e rage velo c i t y, ft/s e c
. , .
' I
I
I ,
I I
10
, . . ,
I
Fi1eu~ :J -l.-Avr raicr ve loc itie > fo r estim atinic trn vrl t imr for s h allo w con c rnt raled Oow .
(2 10-V l -TR -55. Se co nd Ed., Ju ne !98G)
I
20
~· '
APPENDIXB
Storm Inlet Design Data & Calculations (R e vis ed)
12
South Hampton -Phase 3
Depth of Flow in Street Gutter -Revised July 2004
10 -year storm 100-year storm
Gutter A c Location (acres)
-- - ------
E 1 0 .52 0 .50 ·---------
E2 0 .58 0 .50
-----------
-.. ------------
F1 1.1 0 0 .50 -- ------
F2 0.41 0.5 0
-------
H1 3 .35 0 .50
H2 0 .26 0 .50
Tra nsverse (Cro wn) slope (tuft)
for 27' & 39' streets = 0 .0 30 0
Slope
(tuft)
-----
0 .0 102 ------
0.0 160
------
0.0100
0 .01 00
0 .0060
0 .00 60
0 10 Y 10-actual 0 100
(cfs) (ft) (in) (cfs)
---
2.25 0 .237 2.84 3 03 -----------
2 .50 0 .227 2.72 3.38 -.. ---· ---
-------
4 .75 0 .315 3.78 6 .40 -------· ---
1.77 0 .217 2 .61 2.39 ------------
--
8 .80 0.436
1.12 0 .20 2
---------
5.24
2 .4 2
(6 " max. for
sta nda rd c urb )
12 .00
1.51
Straight Crown Flow (Solved to find actual depth of flow in gutter, y):
Q = 0.56 * (z/n) * S 112 * y8 '3 ¢ y ={QI [0 .56 * (z/n) * S 112 ]}318
n =Rough ness Co effi cient = 0 .018
S = Stree UGutte r Slope {tuft)
y = De pth of flow at inl et {ft )
z = Recip rocal of c rown slope :
for 27' & 39' s tree ts = 33
Y100
(ft) (i n)
0.265 3.18 ---
0.253 3.04
-
0 .3 52 4.2 2 ---
0.2 43 2 .92 ---
----------
0.490 5.88 ----
0 .225 2.71
South Hampton
Phase 3
Inlet Length Calculations -Revised July 2004
Inlets In Sump 10 year storm
Inlet# L ength Flow from A c a,. Oc:arryover Orot .. QToti1l+10% Y10.actu•
Exis ting
Inlet#
I
2
Area# (acres) (cfs) (cfs) I from Inlet# (cfs) (cfs) (ft)
10' 6A 3.35 0 .50 8 .80 H · 8.80 9.67 0.334
. 68 0 .26 0 .50 1.12 1.12 1.23 0.155
Inlets On Grad e 1 O year storm
Length
Fl ow ftom y ,. O perfoot Oup-c1ti Obrp .. , Oc:aptured Curry over
Area# (ft) I (in) (ft) (cfs) (cfs) (cfs) (cfs)
5' 5 0 .217
-I·
2 .61 0 .52 2.59 -0 .82 1.77 ·---10' 3+4 0 .315 3 .78 0 .61 6 .09 -1 .34 4.75
Transverse (Crown) slope (ft/ft)
for 27' & 39' streets= 0 .030
z = Rec iprocal of crown slope
for 27' & 39' stree ts = 33
Strai ght Crown Flow (Solved to find actual depth of flow, yl :
a= 0.56 • (z /n ) • s "' • y"' ~ y =(QI [0 .56 • (z/n) • s "'n "'
n =Roughness Coeffic ient= 0 .018
S = StreeVGutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
Capacity of Inlets on grade:
O c = 0.7 • (1/(H , - H2)] • [H,512 -H2
512 ]
Oc = Fl ow capa c it y of in le t (c fs)
H, =a+ y
H2 =a =gutter depression (2" Standard; 4" Recessed)
y = Depth of flow in approach gutter (ft)
j from ln l•t f
I
I
I (In)
I 4 .01
I 1.85
Ot.yp-tot•
(cfs)
0.00
0.00
-
100 year storm
L10-Req'd L10 . .ctu.i a, .. Ounyo.,., 0 101 .. Orot.,..10% Y100
(ft) (ft) (cf s) (c f s) I from Inlet# (cfs) (cfs) (ft) I (In)
8.17 10 12 .00 I 12 .00 13.20 0 .626 17.51
1.51 I 1.51 1.66
·using y,._. r. 0 .583'
100 year storm
OcepMotl 0 10-Tot .i Y100 a,.,,_, Oup.e1ty Obrp•• Oc.,tvrM Ourryover a ... 1 ,.to1a1 Ou,1-to11 0 100.Tot.i s Lac:tu.i
(cfs) (cfs) (ft) I (I n ) (ft) (cfs) (cfs) (cf s) (cfs) I from ln l•t # (cfs) (cfs) (cfs) (ft/ft) (ft)
1.77 1.77 ~.2 .92 0 .54 2.7 1 -0 .32 2.39 I 0 .00 2.39 2.39 0 .0100 5
4.75 I ---
4.75 4 .22 0.64 6.45 -0 .05 6 .40 0 .00 6.40 6.40 0 .0 100 10
APPENDIXC
Storm Pipe Design Data & Calculations (R evised)
I S
South Hampton Subdivision -Phase 3
P . C I I f R d J I 2004 1pe a cu a ions -ev1se U'Y
In let O utlet
Pipe# S ize L en gth S l ope
Invert Elev Invert El ev
(in) (ft) (%) (ft) (ft)
1A 27 50.9 1.40 255.88 255 .17 --
18 27 232 .6 1.40 259.24 255.98 --
2 27 38.5 1.20 259 .80 259.34
--~
3 27 6.0 1.00 260 .26 260 .20
*Actual Flow
(cfs)
-
-
-
-
1 O year s t o rm 100 year sto rm
Design Flow V 10 Travel Time, t110 *Actual Flow De sign Fl ow V 100 % Full % Full
(cf s) (f p s ) (sec ) (mi n ) (cfs) (cfs ) (fps)
25.14 9.4 63.9 5 0 .09 -33.99 9.8 81.9
25.14 9 .4 63.9 25 0.41 -33 .99 9 .8 81.9
23.37 8 .7 64 .1 4 0 .07 -31.60 9 .0 82 .2
18 .62 7 .7 58.6 1 0.01 -25.15 8 .2 72.4
*These valu es reflect the actual flow for the 18" & 24" pip es . The d es ign flow for the se pipe s ize s refl ect s a 2 5% redu c ti o n in pipe area .
Pipe 3 Culvert Calculator Data :
Tailwater = 2 .2 5 ft
Top of Road = 264 .50
Headwater, 10-year = 262.99
Headwater, 100-year = 263.43
Travel Time, tnoo
(sec) (m in)
5 0.09
24 0.40
4 0 .07
1 0.01
South Hampton Subdivision
Phase 3 -Pipe Flow Diagram
Revised July 2004
0 10 (cfs)
Drainage Areas 1 +2 18.62
I J,
Pipe 3 18 .62
J,
Inlet 2 4 .75
J,
Pipe 2 23 .37
J,
Inlet 1 1.77
J,
Pipe 1 B 25 .14
J,
Junction Box 1
J,
Pipe 1A 25 .14
J,
Existi ng Inl e t 9 .92
II Into Existi ng Pipe 35 .06 II
0 100 (cfs)
Drai nage A reas 1+2 J 25 .15
J,
Pipe 3 25 .15
J,
Inlet 2 6.45
J,
Pipe 2 3 1.60
J,
Inlet 1 2 .39
J,
Pip e 1 B 33 .99
J,
Ju ncti o n Bo x 1
J,
Pipe 1A 33 .99
J,
Exi sting Inlet 13 .5 1
Into Exis ting Pipe 47 .50
Pipe lA -10 Year Stor m
Manning Pipe Calcu l ator
Giv en Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
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
27.0000 in
25.1400 cfs
0.0140 ft/ft
0.014 0
17.2655 in
3.9761 ft2
2.6848 ft2
50.0438 in
84.8230 in
9.3638 fps
7.7 2 55 in
63.9464 %
34.0 2 71 cfs
8.5580 fps
Pipe lA -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 Pe rime t er ............... .
Perimet er ...................... .
Veloc ity ....................... .
Hy draulic Radius ............... .
Percent Fu l l ................... .
Full fl ow Fl o wra t e ............. .
Full fl ow v eloci t y ............. .
Circular
Depth of Flow
27.0000 in
33.9900 cfs
0. 0140 ft/ft
0 . 0140
22.1032 in
3.9761 ft2
3 .4841 ft 2
61.0 67 3 in
84.8 2 30 in
9.7558 fp s
8 .21 57 in
81 .8636 %
3 4.0 271 cf s
8.55 80 f ps
So u th Ha mpt o n S ubdi v i sion -Ph ase 3 -Revised July 2 0 04
College S atio n , Texas
Pipe 1 8 -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Dep th .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Perc e nt Full ................... .
F ull flow Flowrate ............. .
Full flow velocity ............. .
Circular
Dept h of Flow
27.0000 in
25. 1400 cfs
0. 0140 ft/ft
0. 0140
17.2655 in
3.9761 ft2
2.6848 ft2
50 .0438 in
84.8 230 in
9.3638 fps
7.7255 in
63.9464 %
34.0271 cfs
8.5580 fps
P ipe 18 -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 ............. .
Ful l flow velocity ............. .
Circular
Depth o f Flow
2 7.0 000 in
33 .990 0 cfs
0. 0140 ft/ft
0. 0140
22.1032 in
3.97 6 1 ft2
3.4841 ft2
61.0673 in
84.8230 in
9.7558 fps
8.2157 in
81.8636 %
34.0271 cfs
8.5580 fps
South Ha mpt o n Su b d i vis ion -Ph ase 3 -Revi sed July 20 04
College Station, Texas
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 ....................... .
Hy draulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
27.0000 in
23.3700 cfs
0 .0120 ft/ft
0. 0140
17.3141 in
3.9761 ft2
2.6935 ft2
50.1450 in
84.8230 in
8.6763 fps
7.7350 in
64.1262 %
31.5030 cfs
7.9231 fps
Pipe 2 -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 ............... .
Perimete r ...................... .
Velocity ....................... .
Hy draulic Radius ............... .
Percent Full ................... .
Full fl o w Flowrate ............. .
Full flo w v elocit y ............. .
Circular
Depth of Flow
27.0000 in
31.6000 cfs
0.0120 ft/ft
0. 0140
22.2066 in
3.9761 ft2
3.4990 ft2
61. 3366 in
84 .8230 in
9 . 0313 fps
8.2145 in
82.2465 %
31 .5030 cfs
7.9 2 31 fps
South Ham pton Subdi v isio n -Ph ase 3 -Revised July 2004
College Station, Texas
Pipe 3 -10 Year Storm
Manning Pipe Calculator
Gi ven Input Data:
Shape .......................... .
Solving for .................... .
Diame te r ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Compute d Results:
Depth .......................... .
Area ........................... ·.
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow v elocity ............. .
Circular
Depth of Flow
27.0000 in
18 .6200 cfs
0 .0100 ft/ft
0 . 0140
15.8169 in
3.9761 ft2
2.4203 ft2
47 .0684 in
84 .8230 in
7.6 932 fps
7.40 47 in
58.5812 %
28.7581 cfs
7.2328 fps
Pipe 3 -100 Year Storm
Manning Pipe Calculator
Given Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Compu ted Results:
Depth .......................... .
Area ........................... .
Wette d Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Veloci t y ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full f l ow velocity ............. .
Circular
Depth of Flow
27 .0000 i n
25.1500 cfs
0 .0100 ft/ft
0. 0140
19.5576 in
3.9761 ft2
3.0845 ft2
54.9753 in
84.8230 in
8.1537 fps
8 .0794 in
72.4356 %
28 .7 581 cfs
7.2328 fps
Sout h Hampt o n Subdi v i sion -Phas e 3 -Revi sed July 2 004
College Sta i o n , Texas
Entered Data:
Pipe 3 -10 Ye a r St o rm
Cul v ert Calculato r
Shape .......................... .
Number of Barrels .............. .
Solving for . . . . . . . . . . . . . .... .
Chart Number . . . . . . . . . . . . .... .
Scale Number ................... .
Chart Description .............. .
Scale Description .............. .
Overtopping .................... .
Flowrate ....................... .
Manning's n .................... .
Roadway Elevation .............. · .
Inlet Elevation ................ .
Outlet Elevation ............... .
Diameter ....................... .
Length ......................... .
Entrance Loss .................. .
Tailwater ...................... .
Computed Results :
Headwater ...................... .
Slope .......................... .
Velocity ....................... .
Circular
1
Headwater
1
1
CONCRETE PIPE CUL VERT; NO BEVELED RING ENTRANCE
SQUARE EDGE ENTRANCE WITH HEADWALL
Off
18.6200 cfs
0 .0140
264.5000 ft
260.2600 ft
260.2000 ft
27.0000 in
6.0000 ft
0 .5000
2 .2500 ft
262.9862 ft Outlet Control
0 .0100 ft/ft
4 .6830 fps
Pipe 3 -100 Year Storm
Culv ert Calculator
Entered Data:
Shape .......................... .
Number of Barrels .............. .
Solving for .................... .
Chart Number ................... .
Scale Number ................... .
Chart Description .............. .
Scale Description .............. .
Overtopping .................... .
Flowrate ....................... .
Manning's n .................... .
Roadway Elevation .............. .
Inlet Elevation ................ .
Outlet Elevation ............... .
Diameter .................... .
Length ......................... .
Entrance Loss .................. .
Tailwater ................ .
Computed Results:
Headwater ..................... .
Slope .......................... .
Velocity ....................... .
Circular
1
Headwater
1
1
CO NCRETE PIPE CULVERT; NO BEVELED RING ENTRANCE
SQUARE EDGE ENTRAN CE WITH HEADWALL
Off
25.1500 cfs
0.0140
264.5000 ft
260.2600 ft
260.2000 ft
27.0000 in
6.0000 ft
0.5 000
2.2500 ft
263.4283 ft Outlet Co nt rol
0 .0 100 ft/ft
6.3253 fps
South Hampton Subdi v i sion -Phase 3 -Revised July 2004
Co llege Stat io n , Texas
EXHIBIT A
Post-Development Drainage Area Map (Revised)
22
Drainage Report
for
South Hampton Subdivision
Phase 3
College Station, Texas
May 2004
Developer:
Nantucket, Ltd.
1101 University Drive East, Suite 108
College Station, Texas 77840
Prepared By:
TEXCON General Contractors
1 707 Graham Road
College Station , Texas 77845
(9 7 9) 764-7743
CERTIFICATION
I , Joseph P. Schultz, Licensed Professional Engineer No . 65889, State of Texas , cetiify that this re port
for the drainage design for Phase 3 of the South Hampton Subdivision in College Station, Texas, was
prepared by me in accordance with the provisions of the City of College Station Drainage Polic y a nd
Design Standards for the owners hereof, with the exception that stom1 water runoff detention is not
being required for this project since it was determined during the development of Phase 1 of th e
subdivision that the site discharges directly into the TxDOT storm drainage system, which discharg es
into a tributary of Alum Creek. This tributary is a part of the Alum Creek primary system , which is a
part of the Lick Creek drainage basin. Nantucket Lake serves as a detention facility for the Alum
Creek drainage basin, and with the South Hampton runoff discharging into this primary system
downstream of the lake, the South Hampton peak runoff will have already passed before the peak
discharge at Alum Creek, therefore resulting in no increase in the peak runoff in Alum Creek .
... :"~,'1:\..~"''"" ,:-\£. OF 1;_\\
, -<.. \>-• • • • • • • • "-+-'·
,, ••• ··-\J" ' #'<'.::> •• • *"· "i'."'t , 1t • ' A ~ . • * '" Ill! * . • I'.. ~..................... • * ... I. JOSEPH .............. ~
::.A ............... ~:. SCHULTZ ~ l~ \ 6sa89 ...... l;gJ ~. 0-<' ·~ <S: Q. ,•' ~ 11 4 ~".CJ I STE~~····'!'.,# ,,ss, .......... ~0J ,,~
5'-0. 0 Lt
TABLE OF CONTENTS
SOUTH HAMPTON SUBDIVISION -PHASE 3
CERTIFICATION .................................................................................................................................................................. 1
TABLE OF CONTENTS ........................................................................................................................................................ 2
LIST OF TABLES .................................................................................................................................................................. 2
INTRODUCTION ................................................................................................................................................................... 3
GENERAL LOCATION AND DESCRIPTION .................................................................................................................. 3
FLOOD HAZARD INFORMATION .................................................................................................................................... 3
DEVELOPMENT DRAINAGE P ATTERNS ................................................ ; ...................................................................... 3
DRAINAGE DESIGN CRITERIA ........................................................................................................................................ 3
STORM WATER RUNOFF DETERMINATION ............................................................................................................... 5
STORM SEWER DESIGN .................................................................................................................................................... 5
STORM DETENTION .........................................................................................................................•................................. 6
CONCLUSIONS ..................................................................................................................................................................... 6
APPENDIX A .......................................................................................................................................................................... 7
Time of Concentration Data & Calculations
APPENDIX B ........................................................................................................................................................................ 11
Storm Inlet Design Data & Calculations
APPENDIX C ........................................................................................................................................................................ 14
Storm Pipe & Channel Design Data & Calculations
EXHIBIT A ............................................................................................................................................................................ 21
Post-Development Drainage Area Map
LIST OF TABLES
TABLE 1 -Rainfall Intensity & Runoff Data ................................................................................................... .4
TABLE 2 -Time of Concentration (tc) Equations ............................................................................................ .4
TABLE 3 -Post-Development Drainage Data .................................................................................................... 5
DRAINAGE REPORT
SOUTH HAMPTON SUBDIVISION -PHASE 3
INTRODUCTION
The purpos e of this report is to provide the hydrological effects of th e construction of Ph ase 3
of the South Hampton Subdivision, and to show that the storm water runoff will be controlled
in such a manner so as to have minimal offsite or downstream impact.
GENERAL LOCATION AND DESCRIPTION
The project is located on a 4 acre tract located in College Station , Texas. The site is wooded
with areas of open land with grass . The existing ground elevations range from elevation 261 to
elevation 273. The general location of the project site is shown on the vicinity map in Exhib it
A .
FLOOD HAZARD INFORMATION
The project site is located in the Alum Creek Drainage Basin, which is a part of the Lick C reek
Drainage Basin. No portion of the site is located in a Special Flood Hazard Area according to
the Flood Insurance Rate Map (FIRM) prepared by the Federal Emergency Management
Agency for Brazos County, Texas and incorporated areas dated February 9, 2000, panel
number 48041C0205-D .
DEVELOPMENT DRAINAGE PATTERNS
Prior to development, storm water runoff from the site generally flows in a northerly direction.
A majority of the runoff flows into an existing concrete flume and then into the existing storm
system, which ties into the storm drainage system in the State Highway 6 right-of-way. A
small portion of the runoff flows in a northwesterly direction where it enters the Nantucket
Drive right-of-way. After development, these flow patterns will typically remain the same,
however, the water captured by the existing flume will be diverted through the proposed storm
system, which ties into a new concrete flume before discharging into the existing flume and
storm drainage system. This system ultimately discharges into Alum Creek. The post-
development drainage area boundaries are shown on Exhibit A .
DRAINAGE DESIGN CRITERIA
The desi gn param eters for the storm sewer are as fo llow s:
• Th e Rational Method is utili zed to d e termin e peak stonn water runoff rates for the
storm sewer design .
• Des ig n Storm Fre qu e ncy
Storm sewer syste m
• Run orrcoe rf:ici e nts
Si ng le Fami ly Res ide ntial
Und eve loped
10 a nd I 00-year s torm eve nt s
c = 0.50
c = 0.30
• Rainra ll Int e ns it y equation s a nd va lu es ror Bra zos Co unt y ca n be ro und in Tab le I .
• Tim e or Co nce ntrati o n, le -C al cu lat io ns a rc based O il th e mclho cl ro un d in th e TR-55
publi ca tion. Re re r to T a bl e 2 lo r th e equati o ns an d App e ndi x A ro r ca lc ul a ti o ns . The
·'
runoff flow paths used for calculating the times of concentration are shown in Exhibit
A. For smaller drainage areas , a minimum tc of l 0 minute s is used to det e nnine th e
rain fa ll intensity values .
TABLE 1 -Rainfall Intensity & Runoff Data
Rainfall Intensity Values
(in/hr)
Storm
Event
Is
110
l2s
lso
1100
Brazos
County:
le=
10 min
7.693
8.635
9.861
11.148
11 .639
I = b I (tc+d)e
I = Rainfall Intensity (in/hr)
tc = U(V*60)
tc = Time of concentration (min)
L = Length (ft)
V = Velocity (ft/sec)
5 )!'.ear storm 10 )!'.ear storm 25 )!'.ear storm 50 )!'.ear storm 100 )!'.ear 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 Highwa)!'.s and Public Transportation H)!'.draulic Manual, page 2-16)
TABLE 2 -Time of Concentration (tc) Equations
Th e tim e of concentration was determined using methods found in TR -55 , "Urban
Hy drology for Small Wat ersheds ." The equations are as follows :
Time of Concentration:
For S heet Flow:
For S h a ll ow Co nce ntrated Fl ow:
Re fer to A p p endi x A fo r ca l c ul ati o n s.
Tc= Tt(sheet now)+ Tt(concentrated sheet now)
where: T 1 =Travel Time , minutes
w he re: T 1 =trave l time , hours
n =M a n ning's rou ghness coefficient
L = fl ow length , feet
P2 = 2 -year, 24-h o u r rainfall = 4.5''
s = la n d s lope , ft/ft
T 1 = L I (60 *V)
w he re: T 1 =trave l time, minut es
V =Ve locity , fp s (S ee Fig 3 -1. /\pp. E)
L = n ow le ng th , feet
STORM WATER RUN O FF D ETERMI NATION
The peak runoff va l ues were determin ed in accordance w ith the criteria present ed in th e
prev ious section for the 5, l 0, 25, 50 , a nd I 00-year s tom1 even ts . The runoff coefficients
for post-deve lopment ca lcu lations are based on th e fut ure d eve lopm e nt of thi s tract , a nd the
peak ru noff va lues dete rmined for th e post-dev e lopment condition are shown in Table 3.
TABLE 3 -Post-Deve lo pm e n t D ra in age Data
Area le
5 y ear s torm 1 O yea r s torm 25 ye ar sto rm 50 year s to rm 100 year sto rm
Area# c Is O s 110 0 10 l2s 0 2s lso O so 1100 0100
(acres) (min) (i n /hr) (cfs) (in/h r) (cf s ) (i n/hr) (cfs ) (i n /hr) (cfs) (in/hr) (c fs)
1 3 .83 0 .50 13.4 6.739 12 .9 0 7 .592 14 .54 8 .684 16.63 9 .831 18 .83 10 .258 19.64
2 1.14 0.50 10.8 7.441 4 .2 4 8 .360 4 .77 9 .552 5.44 10 .8 02 6.16 11 .276 6 .43
3 0 .58 0 .50 10 7.693 2.23 8 .635 2.50 9 .861 2 .86 11.148 3.23 11.639 3 .38
4 0 .52 0 .50 10 7 .693 2 .00 8 .635 2 .24 9.86 1 2 .56 11 .148 2 .90 11 .639 3 .0 3
5 0.41 0 .50 10 7 .693 1.58 8 .635 1.77 9.86 1 2.02 11 .148 2.29 11 .639 2 .39
6 0 .73 0 .50 10 7 .693 2.81 8 .635 3 .15 9 .861 3 .60 11 .148 4.07 11 .639 4.25
The post-development drainage areas are s h own on Ex hibit A. Even though the runoff
coefficient for the developed conditions increases the runoff, th e stom1 sewer system
conveys the runoff directly to a tributary of Alum Creek.
STO RM SEWE R D ES IGN
The stom1 sewer piping for this project has been selected to be Reinforced Concrete Pipe
(RCP) meeting the requirements of ASTM C-76, Class III pipe . The curb in lets 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 were located to maintain a gutter flow d epth of 5" or less, which 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 a t various locations. The runoff
intercepted by the proposed stom1 sewer inlets was calculated using the following
equations . T he depth of flow in th e g utter was d eterm in e d by us ing th e Straight Crown
Flow equ at io n . The flows inte rc e pte d by In le ts l & 2 were ca lcu la ted by using the
C a pac it y of Inl e ts On Grade equ at ion . These equations a nd th e resulting data are
sum m ari z ed in Appendix B. There are no inl e ts in s ump for this phase of t he d ev elopm e nt.
Th e a rea b e tween th e right-of-wa y and th e c urb li ne of th e stree ts w ill b e filled as
n e cessa r y to prov id e a minimum o f 6 " of freebo a rd a bove th e c urb lin e. T hi s will e ns ur e
th a t the run o ff from th e I 00-ye ar s torm eve nt w ill re main w ith in t he s tr eet ri g ht-o f-w ay .
A pp e ndi x C pr ese nt s a s ummary o f th e s to rm se w er p ip e d es ig n p a ram e te rs a nd
ca lc ul a ti o ns. A ll pip es a re 18" in di a m e te r o r large r. Th e pi pes fo r th e s to rm sewe r sys te m
we re d es ig n ed ba se d o n th e I O-yea r s to rm eve nt ; ho\\'evc r, a ll w ill a lso p ass th e 100-yea r
s to rm eve nt w ith o ut a n y h ea d w at e r . As re quired by Co ll ege S ta ti o n , th e ve loc it y o f n ow in
th e s to rm sewe r pip e sys te m is no t IO\\Cr than 2.5 lce t pe r seco nd, and it docs no t exceed
15 fe e t p e r seco nd . f\s th e data s ho\\s , e\"C ll duri ng IO\\ ll O\\" co ndi ti o n , th e ve loc it y in the
pip es an d boxes w ill exceed 2.5 fee t pe r seco nd an d jH C\C 11t se dim e nt bui ld -up in th e pip es
and box es. The maximum flow in the stonn sewer pipe system will occur in Pipe 1.
Appendix C contains a summary of th e Manning pipe calculations for the stonn sewer
system for the 10 and 100-year events . The maximum velocity for the pipe system will be
9 .0 feet per second and will occur in Pip e 2 .
The storm sewer pipe system discharges into a drainage channel which will hav e a 5'
concrete flume to preve nt erosion of th e flow lin e of the channel. The proposed channel is
a "v" shaped channel with 4H: l V side s lopes. It w ill be constructed at a slope of 0.63%,
and it will carry 7 cfs of flow before th e depth of the flow exceeds the concrete flume
height. This is approximately 25% of th e 10-year stom1 event (29 cfs). The depth and
velocity of flow in the channel for the 10 -ye ar storm event are 16 .9" and 3.7 fps, and th e
depth and velocity of flow for the 100-year storm event are 18 .9" and 3.9 fps . To further
prevent erosion of the channel, grass sod will be used to line the channel bank s to a
minimum depth of 1.5 feet, which is greater than the 10-year storm flow depth. The
channel will be constructed with a minimum depth of 2.5 feet to restrict the flow to the
drainage easement. The proposed channel discharges into an existing drainage channel
that also has a concrete flume .
STORM DETENTION
The storm water runoff detention is not being required for this project since it was
determined during the development of Phase 1 of the subdivision that the site discharges
directly into the TxDOT storm drainage system, which discharges into a tributary of Alum
Creek. This tributary is a part of the Alum Creek primary system, which is a part of the
Lick Creek drainage basin. Nantucket Lake serves as a detention facility for the Alum
Creek drainage basin, and with the South Hampton runoff discharging into this primary
system downstream of the lake, the South Hampton peak runoff will have already passed
before the peak discharge at Alum Creek, therefore resulting in no increase in the peak
runoff in Alum Creek.
CONCLUSIONS
The construction of this project will increase the storm water runoff from this site, however
it should not have a significant impact on the surrounding property. No flood damage to
downstream or adjacent landowne rs is ex pected as a result of this dev e lopm e nt.
7
APPENDIX A
Time of Concentration Data & Calculations
Time of Concentration Calculations
Refer to Exhibit A for flow path us ed fo r calculations .
Drainage Area #1:
Shee t Flow: Flow len gth = 125 ' = L
Slope = 3 .7%
n = 0 . 15, s hort grass, prairi e
P2 = 4 .5"
ti = 0.007 (0 .15 * 125)08
(4 .5)05 (0.037)04
ti = 0 .129 hours= 7.7 minutes
Shallow Concentrated Flow: Flow length = 535' = L
Slope = 2 .1%
Flume Flow:
Drainage Area #2:
Sheet Flow:
For unpaved surface at 2.1%, Velocity (V) = 2.3 fps (see Fig. 3-1)
~ ti = 535' I (60*2 .3) = 3.9 minutes
Flow len gth = 355' = L
Slope = 2.7 %
For pave d s urface at 2.7%, Velocity (V) = 3.3 fps (see Fig. 3-1)
ti = 355 ' I (60*3 .3) = 1.8 minutes
Tc = 7 .7 + 3.9 + 1.8 = 13.4 minutes
Flow length = 125' = L
Slope = 3 .1%
n = 0 .15 , short grass, prairie
P2 = 4 .5"
ti = 0.007 (0 .15 * 125)°-8
( 4 .5)0 ·5 (0.031 )0 .4
ti = 0 .13 8 hours= 8.3 minutes
Shallow Concentrated Flo w: Flow length = 195 ' = L
Slope = 1.8%
Flulll e Flow :
For unpaved s urfa ce at 1.8 %, Velocity (V) = 2 .15 fps (see Fi g. 3-1)
t1 = 195 ' I (60*2.15) = 1.5 minute s
Fl o w le ng th = 200' = L
S lop e = 2 .7%
For paved s urfa ce a t 2.7%, Ve locity (V) = 3.3 fp s (see 17ig . 3-1)
t 1 = 200 ' I (60*3.3) = 1.0 minutes
T c= 8.3 + 1.5 + 1.0 = 10 .8 minut es
....
'+--....
'+-
CV a.
0 ..-.,,
CV .,,
'-
:J
0 u
'-
CV ..... ..,
:x
3-2
. 50 -
.20 -
.10
. 06
.04 -
. 02 -
.01 -
.005
I
1
j
' I
' I
I
'
j
'I
' b
q, l_ .... b1 ~ q,
'tr ~, ~~)
I
' I
I
2
)
' 1 •.
1,
I
4
J
J ..
;
J
J
I
I
6
i
I
J
' '
Av e rage ve l ocity, ft/sec
. . .
I
I .,
~
I I
10
. . .
j
I
FiK"U~ :1 .t.-r\vcral(r veloc iti e!!I fl'' C:'\lima linl( l rJvcl time for ~hallow concenlr.iled now.
(2 10 -V!-TR-55. Second Cd .. .June l 98G)
I
20
.f
-I
.f
APPENDIXB
Storm Inlet Design Data & Calculations
11
South Hampton -Phase 3
Depth of Flow in Street Gutter
Gutter A c Slope
Location (acres) (ft/ft)
----------------
E1 0 .52 0 .50 0 .0102
·-
--------------·· ---·---·-- -
E2 0 .58 0 .50 0 .0160 ------------------
--·-----------------
F1 1 .10 0 .50 0.0100
F2 0.41 0 .50 0 .0100 ----------
10-year storm 100-year storm
Q10 Y10-actua l Q100 Y100
(cfs) (ft) (in) (cfs) (ft)
-------------------·-------
2 .2 5 0 .237 2 .84 3 .03 0 .265
·-----------------· --
2 .50 0 .227 2.72 3 .38 0 .253 -------------------
------------------------
4 .75 0 .315 3.78 6.40 0 .352 ---------
1.77 0 .217 2.61 2 .3 9 0 .243 -------------
(6" max. for
Transverse (Crown) slope {ft/ft}
for 27' streets = 0.0300
· standard curb)
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:
for 27' streets = 33
(in)
3 .1 8
3 .04
4.22
2 .92
South Hampton
Phase 3
I nl et Length C alculations
Inlets On Grade
Inl et# l e ngt h Flo w from
Area#
1 5' 5
2 10' 3+4
Y10
(ft) I (In)
0.217 I 2.61
0 .315 3.78
1 o year storm
Operfool Cup.elf) ab)'pUa ac.,tured O unyo.,.,
(ft) (cfs) (cfs) (cfs) (cfs) I 1rom Inlet#
0 .52 2.59 ·0.82 1.77 I --
0 .6 1 6 .09 ·1 .34 4.75 I
Transverse !Crown) slo pe !tvftl
fo r 27' streets = 0 .030
z = Reciprocal of crown slope
for 27' streets = 33
Straight Crown Fl ow (So lved to find ac tual depth of flow, y):
a= 0 .56 • (z /n) • s '" · y"' ¢ y =(Qt [0.56 • (z/n) • s '"n"'
n =Roughness Coefficient = 0 .018
S = StreeVGutter Slope (tvft)
y = Depth of flow at in let (ft)
Capacity of Inlets on grade:
0 0 = 0.7. [1 /(H , · H 2 )J '[H 1
512 • H 2
512 ]
O c = Flow capac ity of inlet (cfs)
H1 =a +y
H2 = a =gu tter depression (2" Sta nda rd; 4" Re cessed )
y = Depth of flow in approach g utter (ft )
100 year storm
Oi.y,.-. 0c ...... 0 10 .fot.i Y100 a,_.,_t O c.,..::tty Qbyp•• <lc.,tured Oc.,.ryover Q byp-to!M Oe.,1-tou 0 100.Total s L.,tu.,
(cfs) (cfs) (els) (ft) I (In) (ft) (cf s) (cfs) (cfs) (cfs) j from Inlet# (cfs) (cfs) (cfs) (ft/ft) (ft)
0 .00 1.77 1.77 o.243 I 2 .92 0.54 2.71 -0 .32 2 .39 I 0.00 2.39 2.39 0.01 00 5
0 .00 4 .75 4 .75 o .352 I 4 .22 0.64 6.45 -0 .05 6.40 I 0.00 6.40 6.40 0.0100 10
APPENDIXC
Storm Pipe & Channel Design Data & Calculations
14
South Hampton Subdivision -Phase 3
Pipe Calculations
Inlet Outlet 1 O year storm 100 year storm
Pip e# Siz e Length S l ope
Invert Elev Invert Elev *Actual Flow Design Flow V10 %Full
Travel Time, tT1o *Actual Flow Des ign Flow V100 %Full
Tra vel T ime , tnoo
(in ) (ft) (%) (ft) (ft) (cfs) (cfs) (fps) (sec) (min) (cfs) (cfs) (fps) (sec) (min)
1 30 12.0 0.75 259 .39 259 .30 -25 .83 7.4 66.6 2 0 .03 -34 .86 7.6 88 .4 2 0 .03 --
2 27 36.6 1.20 260 .08 259 .64 -24 .06 8 .7 65.4 4 0 .07 -32 .4 7 9 .0 8 5 .0 4 0 .07 ----
3 27 6.0 1.00 26 1.06 261 .00 -19 .31 7.8 60 .0 1 0 .01 -26 .07 8 .2 74 .6 1 0 .01
'The se va lues reflec t the actual flow fo r the 18" & 24" p ipes . The design flow for these pipe sizes reflects a 25% reduction in pipe area .
South Hampton Subd iv ision
Phase 3 -Pipe Flow Diagram
0 10 (cfs)
Drainage Areas 1 +21 19 .31
J,
Pipe 3 19 .31
J,
Inlet 2 4 .75
J,
Pip e 2 24.06
J,
Inlet 1 1.77
J,
Pipe 1 25 .83
J,
Drainage Area 6 3 .15
i nto Propose d Drain age Cha nnel II 28 .98 II
0 100 (cfs)
Dra inage Areas 1+2 26.07
J,
P ipe 3 26.07
J,
Inlet 2 6.4 0
J,
Pi pe 2 32 .47 .
J,
Inlet 1 2.39
J,
Pipe 1 34 .86
J,
Drainage Area 6 4 .25
Into Proposed Drainage Cha nne l II 39 .11
Pipe 1 -10 Year Storm
Manning Pipe Calculator
Gi ven Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning ' s n .................... .
Compu ted Results:
Depth .......................... .
Area ......................... · ·· ·
Wetted Area .................... .
Wetted Pe r imeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hy draulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
30 .0000 in
25.8300 cfs
0.007 5 ft/ft
0.014 0
19.9855 in
4 .9087 ft2
3.4736 ft2
57 .2883 in
94.2478 in
7 .4362 fps
8.731 2 i n
66.6184 %
32 .9846 cfs
6 .7196 fps
Pipe 1 -100 Year Storm
Manning Pipe Calculator
Giv en Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Pe rimeter ............... .
Peri meter ...................... .
Velocity ....................... .
Hy drauli c Radius ............... .
Percent Full ................... .
Full flo w Fl ow r a te ............. .
Full flo w v el o cit y ............. .
Sout h Ha mp t o n S u bdivisio n -Ph ase 3
Colleg e Stat i o n, Texas
Circular
Depth of Flow
30.0000 in
34.8600 cfs
0 .0075 ft/ft
0 . 0140
26.522 1 in
4.9087 ft2
4.591 5 ft2
73.4019 in
94 .2478 i n
7.59 23 fps
9.00 76 i n
88.4 071 %
3 2 .9846 cfs
6 .7 1 96 f p s
Pipe 2 -10 Year S~or m
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Com puted Result s:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hy draul ic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
27.0000 i n
24.0600 cfs
0 .0120 ft /ft
0. 0140
17 .6693 in
3.9761 ft2
2.7572 ft2
50.8888 in
84 .8230 in
8 .72 63 fps
7.8020 in
65.4420 %
31.5030 cfs
7.9231 fps
Pipe 2 -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 Ful 1 ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
South Ha mp t o n S ubd i vjs i o n -Ph ase 3
Co l lege S t a ti o n , Te x as
Circular
Depth of Flow
27.0000 in
32.4700 cfs
0.0120 ft/ft
0 . 0140
22.9577 in
3.9761 ft2
3.6031 ft2
63.3687 in
84.8230 in
9. 0116 fps
8.1878 in
85.0284 %
31.5030 cfs
7 .9231 fps
P i p e 3 -10 Year S~or m
Mann i ng Pipe Calc u la tor
Gi v en I nput Da t a:
Shape .......................... .
S olving fo r .................... .
Di amete r ....................... .
Flowrat e ....................... .
Slope .......................... .
Manning's n .................... .
Comp u ted Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow v elocity ............. .
Ci rc ular
Depth o f Fl ow
2 7 .0000 i n
19 .3 1 00 cfs
0. 010 0 f t/ft
0.0 140
16 .1940 in
3.9761 ft 2
2.4898 ft2
47 .8360 in
84.8230 in
7 .7556 fps
7.4950 in
59 .9779 %
28 .7581 cfs
7 .2328 fps
Pip e 3 -100 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
We tted Area .................... .
We tte d P erimeter ............... .
Peri meter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocit y ............. .
S o uth Ha mp t o n Subdi v i s i o n
Col l ege S t at i o n, T exas
P h a se 3
Circular
Depth of Flow
27.0000 in
26.0700 cfs
0.0100 ft/ft
0 . 0140
20.1482 in
3 .9761 ft2
3 .1822 ft 2
5 6.3142 i n
8 4.8230 i n
8.1925 fps
8.1371 in
7 4 .6230 %
28.7581 cfs
7.2328 fps
Dr ainage Channel -1 0 Ye ar S t orm
Channel Calculato r
Give n Input Data :
Shape .......................... .
Solving for .................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Height ......................... .
Bot tom width ................... .
Left slope ..................... .
Right slope .................... .
Computed Results:
Depth .......................... .
Velocity ....................... .
Full Flowrate .................. .
Flow area ...................... .
Flow perimeter ................. .
Hydraulic radius ............... .
Top width ...................... .
Area ........................... .
Perimeter ...................... .
Percent full ................... .
Trape zoidal
Depth of Flow
2 8 .9 8 00 cfs
0 .0 063 ft/f t
0 .0 25 0
30 .0000 in
0 .0000 in
0 .2 5 0 0 ft/ft (V/H)
0 .2 50 0 ft/ft (V/H)
16.8884 in
3 .6578 fps
134.1280 cfs
7 .92 27 ft2
139.2 653 in
8.19 2 1 in
135 .1072 in
25 .0000 ft2
247.3863 in
56 .2946 %
Drainage Channel -100 Year Storm
Channel Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Height ......................... .
Bot tom width ................... .
Left slope ..................... .
Right slope .................... .
Comput e d Results:
De pth .......................... .
Ve loc i ty ....................... .
Ful l Fl owra te .................. .
F l ow area ...................... .
Flow perimeter ................. .
Hydrau li c r adi u s ............... .
Top width ...................... .
Area ........................... .
Perimeter ...................... .
Percent full ................... .
So u t h Hampt o n S ubdivisio n -P h ase 3
Co]leg e St ati o n, T exas
Trapezoidal
Depth of Flow
39. llOO cfs
0.0063 ft/ft
0.0250
30.0000 in
0 .0000 in
0.2500 ft/ft (V/H)
0 .250 0 ft/ft (V/H)
18.897 7 i n
3.9425 fps
134. 1280 cfs
9 .9201 ft2
155.8346 in
9.1667 in
151 .1818 in
25.0000 ft 2
247 .38 63 in
62.9 92 4 %
EXHIBIT A
Post-Development Drainage Area Map
2 1
Drainage Report
for
South Hampton Subdivision
Phase 3
College Station, Tex as
May 2 004
R evis ed July 2004
D eveloper:
Nantu cket, Ltd .
1 101 Un iversity Drjve East, Suite 108
Co ll ege Stati on, Texas 7784 0
Prepared By:
TEXCON Genera] 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
revised report for the drainage design for Phase 3 of the South Hampton Subdivision in College
Station, Texas, was prepared by me in accordance with the provisions of the City of College Station
Drainage Policy and Design Standards for the owners hereof, with the exception that storm water
runoff detention is not being required for this project since it was detennined during the dev e lopm e nt
of Phase l of the subdivision that the site discharges directly into the TxDOT storm drainage system,
which discharges into a tributary of Alum Creek. This tributary is a part of the Alum Creek primary
system, which is a part of the Lick Creek drainage basin. Nantucket Lake serves as a detention facility
for the Alum Creek drainage basin, and with the South Hampton runoff discharging into this primary
system downstream of the lake, the South Hampton peak runoff will have already passed before the
peak discharge at Alum Creek, therefore resulting in no increase in the peak runoff in Alum Creek.
TABLE OF CONTENTS
SOUTH HAMPTON SUBDIVISION -PHASE 3
R evised July 2004
CERTIFICATION .................................................................................................................................................................. 1
TABLE OF CONTENTS ........................................................................................................................................................ 2
LIST O F TABLES .................................................................................................................................................................. 2
INTRODUCTION ................................................................................................................................................................... 3
GENERAL LOCATION AND DESC RIPTION .................................................................................................................. 3
FLOOD HAZARD INFORMATION .................................................................................................................................... 3
DEVELOPMENT DRAINAGE PATTERNS ....................................................................................................................... 3
DRAINAGE DESIGN CRITERIA ........................................................................................................................................ 3
STORM WATER RUNOFF DETERMINATION ............................................................................................................... 6
STORM SEWER DESIGN .................................................................................................................................................... 6
STORM WATER DETENTIO N ........................................................................................................................................... 7
CONCLUSIONS ..................................................................................................................................................................... 7
APPENDIX A .......................................................................................................................................................................... 8
Time of Concentration Data & Calculatioll s (Revised)
APPENDIX B ........................................................................................................................................................................ 12
Storm Inlet D esign Data & Calculation s (Revised)
APPENDIX C ........................................................................................................................................................................ 15
Storm Pipe Design Data & Calculations (Revised)
EXHIBIT A ............................................................................................................................................................................ 22
Po st-Developm ent Drainage Area Map (Revised)
LIST OF TABLES
TABLE 1 -Rainfall Intensity & Runoff Data .................................................................................................... 5
TABLE 2 -Time of Co ncentration (tc) E quations ............................................................................................. 5
TABLE 3 -Post-Development Drainage Data -R evised ................................................................................... 6
DRAINAGE REPORT
SOUTH HAMPTON SUBDIVISION -PHASE 3
Revise</ July 2004
INTRODUCTION
The purpose of this revised report is to provide the hydrological effects of the construction of
Phase 3 of the South Hampton Subdivision , and to show that the storm water runoff will be
controlled in such a m a nner so as to ha ve minimal offsite or downstream impact.
GENERAL LOCATION AND DESCRIPTION
The project is located on a 4 acre tract located in College Station, Texas. The si te is wooded
with areas of open land with grass. The existing ground elevations range from elevation 26 l to
elevation 273. 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 Alum Creek Drainage Basin, which is a part of the Lick Creek
Drainage Basin . No portion of the site is located in a Special Flood Hazard Area according to
the Flood Insurance Rate Map (FIRM) prepared by the Federal Emergency Management
Agency for Brazos County, Texas and incorporated areas dated February 9, 2000, panel
number 48041C0205-D.
DEVELOPMENT DRAINAGE PATTERNS
Prior to development, storm water runoff from the site generally flows in a northerly direction .
A majority of the runoff flows into an existing concrete flume and then into th e existing stom1
system, which ties into the storm drainage system in the State Highway 6 right-of-way . A
small portion of the runoff flows in a northwesterly direction where it enters the Nantucket
Drive right-of-way. After development, these flow patterns will typically remain the same,
however, the water captured by the existing flume will be diverted through the proposed stom1
system, which ties into an existing storm drain inlet before discharging into th e storm drainage
system. This system ultimately discharges into Alum Creek. The post-development drainage
area boundaries are shown on Exhibit A.
DRAINAGE DESIGN CRITERIA
The desi gn parameters for the storm sewe r are as fo llows:
• The Rational Method is utili zed to d etermin e peak sto rm wate r runo ff rat es fo r the
storm sewe r desi g n .
• Design Storm Frequency
Storm sewer system
• Runoff Co e ffic ients
Single Fa mil y R esi d e nti a l
Und eve loped
I 0 a nd I 00-year s torm even ts
c = 0 .50
c = 0 .30
• Rainfall Int e ns it y eq uat io ns a nd va lu es for Bra zos Co unt y ca n be louncl in Tab le 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 times of concentration are shown in Exhibit
A. For smaller drainage areas , a minimum tc of 10 minutes is used to detennine the
rainfall intensity values.
TABLE 1 -Rainfall Intensity & Runoff Data
Rainfall Intensity Values
(in/hr)
Storm
Event
Is
110
'2s
lso
1100
Brazos
County:
t c =
10 min
7.693
8.635
9.861
11 .148
11 .639
I = b I (tc+d)e
I = Rainfall Intensity (in/hr)
tc = U(V*60)
le = Time of concentration (min)
L = Length (ft)
V = Velocity (ft/sec)
5 y__ear storm 10 y__ear storm 25 y__ear storm 50 y__ear storm 100 y__ear 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 Hiqhway__s and Public Transportation Hy__drau/ic Manual, page 2-16)
TABLE 2 -Time of Concentration (tc) Equations
Th e time of concentration was determin ed using methods found in TR-55 , "Urban
Hy drology for Small Wat ersh eds. " The equ ations are as follows:
Time of Concentration:
For Sheet F lo w :
For S hallow Conce ntra ted Fl ow:
R efer to Appendix A for ca lcu la ti ons.
Tc= Tt(shcct flow)+ Tt(concenlraled sheel flow)
where: T 1 =Travel Time, minutes
where: T 1 = travel time , hours
n =Manning 's rou ghne ss coeffic ie nt
L = flo w len g th, fee t
P 2 = 2-year, 24 -hour rainfall = 4.5 "
s = land s lope, ft /ft
T 1 = LI (60*V)
where: T 1 =tra ve l time , minu tes
V =Veloc it y, fps (See Fi g 3-1, App . E)
L = flo w le ng th , feet
STORM WATER RUNOFF DETERMINATION
The peak runoff valu e s were determin e d in accord a nce with the criteria pre s e nt ed in th e
previous s e ction for th e 5 , 10 , 25, 50 , and 100-year storm events . The runoff co e ffici e nts
for post-development calculations are based on the fut ure development of this tract , and th e
peak runoff va lu es determined for the post-development condition are shown in Tabl e 3 .
TABLE 3 -Post-Deve lopme n t Dra in age Data -Revised
tc
5 year s t o rm 10 year sto rm 25 year storm 50 year storm 100 year storm
Area
Area# c 15 Os 110 0 10 12 5 025 150 Oso 1100 0100
(ac res) (min) (in/h r ) (cfs ) (in/h r) (c f s ) (in/hr) (cfs ) (in/hr) (cfs) (in/hr) (cfs)
1 3 .65 0.50 13 .4 6.739 12 .30 7 .592 13 .85 8.684 15 .85 9 .831 17 .94 10 .258 18 .72
2 1.14 0.50 10 .8 7.441 4 .24 8.360 4.77 9 .552 5.44 10 .802 6 .16 11 .276 6.43
3 0 .58 0 .50 10 7 .693 2 .23 8.635 2 .50 9 .86 1 2.86 11 .148 3 .23 11.639 3 .38
4 0 .52 0.50 10 7 .693 2.00 8.635 2.24 9 .861 2.56 11 .148 2 .90 11 .639 3.03
5 0.41 0 .50 10 7.693 1.58 8.635 1.77 9 .861 2.02 11 .148 2.29 11 .63 9 2 .39
6A 3 .35 0 .50 27.0 4 .612 7 .73 5 .251 8 .80 6 033 10.10 6.860 11.4 9 7.16 3 12.00 --------------
68 0 .2 6 0 .50 10 7.693 1.00 8 .635 1.1 2 9.861 1.28 11.148 1.4 5 11 .639 1.51
The post-development drainage areas are shown on Exhibit A. Even thou g h th e runoff
coefficient for the developed conditions increases the runoff, the stonn sewer s ystem
conveys the runoff directly to a tributary of Alum Creek.
STORM SEWER DESIGN
The storm sewer piping for this project has been selected to be Reinforc ed Concrete Pipe
(RCP) meeting the requirements of ASTM C-76 , Class III pipe . The curb inlets will be
cast-in-place concrete. Appendix B presents a summary of the storm sewer inl e t design
parameters and calculations. The inlets were designed based on a 10-year desi gn storm .
As per College Station guidelines, the capacities of inlets in sump were reduc ed by 10 % to
allow for clogging.
Inlets were located to maintain a gutter flow depth of 5" or less , which will pre vent the
spread of water from reaching the crown of the road for the 10-year stom1 eve nt . Refer to
Appendix B for a summary of the gutter flow depths at various locations . The runoff
intercepted b y the proposed stom1 sewer in lets w a s calculated using th e follo w in g
equations . The depth of flow in the gutter was d e te rmined b y using th e Straig ht C rown
Flow equa tion. Th e flows intercepted by Inlets 1 & 2 were calculated b y usin g th e
Capacity of In lets On Grade equation. These equ a tions and th e resultin g d a ta a r e
summari zed in App e ndix B . There are no propo sed in le ts in s ump for thi s ph ase of th e
developm e nt . The area b e tw ee n the ri ght-of-wa y and th e curb lin e of th e s tr eets w ill be
filled as necessary to pro v ide a minimum of 6" of fr ee board a bove th e c urb lin e. T hi s will
e nsure th a t th e runoff from th e I 00-ye ar storm e ve nt w il l re main w ithin th e s treet ri g ht -of-
wa y.
A pp e ndi x C pr ese nt s a s umm a r y o f th e s torm sewe r pip e d es ig n pa ra m e te rs a nd
ca lc ul a ti o ns. A ll pip es a re 18" in diam e te r or la rger . Th e pip es for th e s to rm sewe r sys te m
w e re d es ig ned ba sed o n th e 10 -year s to rm ev e nt ; ho w e ve r, a ll will a lso pass th e 100-yea r
s torm eve nt without a n y hea dwat e r . A s required b y C oll ege St a tion , th e ve loc it y o f n ow in
th e s to rm sew e r pip e sys te m is no t lowe r than 2.5 fee t pe r seco nd , and it docs no t exceed
15 fee t p e r seco nd . As th e d;1ta s hows , eve n duri ng low ll ow co nditi on s. the\ e loc it y in the
pipes will exceed 2 .5 feet per second and prevent sediment build-up in the pipes. The
maximum flow in th e stonn sewer pipe system will occur in Pipes IA & IB. Appendix C
contains a summary of the Maiming pipe calculations for the stonn sewer system for the l 0
and 100-year events. The maximum velocity for the pipe system will be 9.8 feet per
second and will occur in Pipes IA & I B. The storm sewer system from Crauberry Drive
to Wi11drift Cove will be located in a 15' public drainage easeme11t. The storm sewer
pipe system passes the I 00-year storm eveut runoff, therefore, 1w overlaud flow is
proposed for the drainage easemeut. The headwater for Pipe No. 3 is elevatiou 263.43
for the JOO-year storm event. The proposed top of the street is elevation 264.50, as is the
adjace11t top of slope of the existi11g draiuage chanuel. Therefore, the runoff ill the
existi11g cha1111el upstream of Crauberry Drive will be contained within the drainage
easement.
The storm sewer pipe system discharges into a11 existi11g storm drain inlet. This inlet is a
I 0' ill/et in a sump, and the gutter depth at this inlet is 5.28 "for the 10-year storm event,
a11d 5. 88 "for the 100-year storm event. The existi11g 24 "pipe a11d headwall a11d the
concrete flume, which collect the runoff from an existiug draiuage ditch aud discharge
iuto the existing storm inlet, will be removed and replaced with the proposell storm sewer
piping. The existing ditch will be filled to drain as shown on the coustruction drawings.
STORM WATER DETENTION
The storm water runoff detention is not being required for this project since it was
determined during the development of Phase 1 of the subdivision that the site discharges
directly into the TxDOT storm drainage system, which disch arges into a tributary of Alum
Creek. This tributary is a part of the Alum Creek primary system, which is a part of the
Lic k Creek drainage basin. Nantucket Lake serves as a detention facility for the Alum
Creek drainage basin, and with the South Hampton runoff discharging into this primary
system downstream of the lake, the South Hampton peak runoff will have already passed
before the peak discharge at Alum Creek, therefore resulting in no increase in the peak
runoff in Alum Creek.
CONCLUSIONS
The construction of this project will increase the stonn water runoff from this site;
however, it s hould not have a significant impact on the surrounding prope1iy . No flood
damage to downstream or adjacent landowners is expected as a result of this development.
APPENDIX A
Time of Concentration Data & Calculations (Revised)
Time of Concentration Calculations
Refer to Exhibit A for flow paths used for calculations.
Drainage Area #1:
Sheet Flow: Flow length = 125' = L
Slope= 3 .7%
n = 0. 15 , short grass, prairie
P2 = 4.5"
ti= 0.007 (0 .15 * 125)08
(4.5)0 5 (0 .037)04
ti= 0.129 hours= 7 .7 minutes
Shallow Concentrated Flow: Flow length = 535' = L
Slope= 2.1%
Flume Flow:
Drainage Area #2:
Sheet Flow:
For unpaved surface at 2.1 %, Velocity (V) = 2 .3 fp s (see Fig. 3-1)
-7 ti= 535 ' I (60*2 .3 ) = 3.9 minutes
Flow length= 355' = L
Slope= 2.7%
For paved surface at 2 .7%, Velocity (V) = 3 .3 fps (see Fig . 3-1)
ti= 355' I (60*3.3) = 1.8 minutes
Tc= 7 .7 + 3.9 + 1.8 = 13.4 minutes
Flow length= 125' = L
Slope= 3.1%
n = 0.15, short grass, prairie
P2 = 4.5"
ti= 0.007 (0.15 * 125)°-8
(4.5)05 (0.031)0 4
ti= 0 .138 hours= 8 .3 minutes
Shallow Concentrated Flow: Flow length = 195' = L
Slope= 1.8%
Fluine Flow :
For unpaved surface at 1.8%, Velocity (V) = 2 .15 fps (se e Fig. 3-1)
-7 ti = 195' I (60*2 . l 5) = 1.5 minutes
Flow length= 200' = L
Slope= 2.7 %
For pa ve d surface at 2 .7%, Veloc it y (V) = 3 .3 fps (see Fi g. 3-1)
ti= 200' I (60*3.3) = 1.0 minute s
Tc= 8 .3 + 1.5 + 1.0 = l 0.8 minutes
Time of Concentration Calculations, continued
(Revised July 2004)
R efe r to Exhibit A for flow paths used for calcu lation s.
Drainage Area #6A:
Sh eet Flow:
Pa ve ment Flow:
Flow length= 215 ' = L
Slope = 3 .0%
n = 0 .24 , dense grass
P2 = 4.5"
ti = 0 .007 (0 .2 4 * 215)0 8
(4.5)0·5 (0.03)04
ti= 0.315 hours= 18 .9 minutes
Flow length = 68 ' = L
Slope = 1.23 %
For paved surface at 1.23 %, Velocity (V) = 2.2 fps (see Fig . 3-1)
ti = 68 ' I (60 *2.2) = 0.5 minutes
Similarly:
L = 23 7', S = 2%, V = 2.85 fps , ti = 1.4 minutes
L = 217', S = 3%, V = 3.6 fps, ti= 1.0 minutes
L = 503 ', S = 6%, V = 1.6 fps , ti= 5.2 minutes
Slope = 2 .7%
Tc= 18.9 + 0 .5 + 1.4 + 1.0 + 5.2 = 27.0 minutes
....
'+--....
'+-
GJ a.
0 .-
Ill
GJ
Ill
'-::s
0
(.J
'-
Q.I
~ .,
:JC
3-2
.50
.20 -
.10
.06
.04
. 02 -
.01 -
.005
I
l
j
-~
I
' I
I
'
' ,
' .
"b
q, I_'-b I ~ q,
'b ~, ::::,0 Q.'t1
)
I )
I
' I
z
1,
'
I
4
J
J
I
J
j
I
I
I
6
j
I
'
' I
Av e ra ge ve lo ci ty, f t /sec
. . . .
J
I
I
I ,
I I
10
. . .
I
Fiicu"' :J-L -,\v~raK~ vc loci t ic> for cs li ma t i nK l rnvd tim e for s h allo w c on c ~nl ra t c d Oow _
(2 10-V !-TR -55 . Seco nd Ed .. Ju ne 198G)
I
20
l ~·
'.
APPENDIXB
Storm Inlet Design Data & Calculations (Revised)
12
South Hampton -Phase 3
Depth of Flow in Street Gutter -Revised July 2004
10-year storm
Gutter A c Slope 0 10 Y 10-actua l 0 100
Location (acres) (ft/ft) (cfs) (ft) (in) (cfs)
-------------------
E1 0 .52 0 .50 0 .010 2 2.25 0 .2 37 2 .84 3 .03
--~---· --· -------------
E2 0 .58 0 .5 0 0 .01 60 2 .50 0 .227 2 .72 3.38
------------------
--------------------------------
F1 1.10 0 .50 0.0100 4 .75 0 .315 3.78 6 .4 0
----------------------
F2 0.41 0 .50 0.0100 1.77 0 .2 17 2 .61 2.39 --------------·------------------------
H1 3 .35 0 .50
H2 0 .26 0 .50
Transvers e (Crown ) slope {ft/ft)
for 27' & 39' streets = 0 .0300
0.0060
0.0060
8 .80 0.4 36
1.12 0 .202
5 .24
2.42
(6" ma x . fo r
s tandard curb)
Straight Crown Flow (Solved to find actual depth of flow in gutter, y):
Q = 0 .56 * (z/n) * S 112 * y8 '3 ~ y ={QI [0.56 * (z/n) * S 112]}318
n = Roughness Coefficient= 0 .018
S = StreeUGutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
z = Re cipro cal of crown slope :
for 27' & 39 ' streets = 33
--
12 .00
1.51
100-year storm
Y 100
(ft) (in)
--
0 .265 3.18 --
0 .253 3.04 -
-
0 .352 4.22 --
0 .24 3 2 .92
-
----
0.4 90 5.88 ---
0.225 2.71 ----
South Hampton
Phase 3
Inlet Length Calculations -R evised July 2004
Inl ets In Sump 1 O year storm
Inlet# Length Flowlro m A c o,, O c •rtyovM Orot•I O rot•l+t0% YtO.-::t\.l.i
Ex1st111g
Inlet#
1
2
Area# (a cres) (els) (els) I from Inlet# (els) (els) (ft)
10' 6A 3.35 0.50 8.80 I 8.80 9.67 0.334 -·-->-----
68 0.26 0.50 1.12 I 1.12 1.23 0.155
Inlets On Grade 10 year storm
Length Flow from y,, Oper fool Oupaclt) O bypu• Oup1ured Oc•ryover
Area# (ft) I (In) (ft) (els) (els) (els) (els)
5' 5 0 ~1 ~ 0.52 2.59 -0 .82 1.77 ---10' 3+4 0.31 5 3.78 0.61 6.09 ·1.34 4.75
Transverse (Crown) slope (ft/ft)
for 27' & 39' streets = 0.030
z = Reciprocal of crown slope
for 27' & 39' streets = 33
Straight Crown Flow (Solved t o find actua l depth of flow, yl :
Q = 0.56 • (z/n ) • s 112 • y"' ~ y ={QI [0 .56 • (z/n ) • s "'n'"
n =Roughness Coefficient= 0 .018
S = StreeVGutte r Slope (fVft)
y = Depth of flow at inlet (ft )
Ca pacity of Inlets on grade :
Oc = 0.7' [1 /(H , · H ,)] '[H ,'12 -H 2
512 ]
O c = Fl ow capacity o f inle t (c fs)
H , =a + y
H 2 =a= gutter depression (2" Standard; 4" Recessed)
y = Depth of flow in approach gutter (ft)
I from Inlet f
I
I
I (I n)
I 4.01
I 1.85
Obyp-tot•
(els)
0.00
0.00
1 OD year storm
L 10-R.eq 'd• L 10-aetu.i 0 100 O c.nyoYet Orot.i Orot.i+t"-Y100
(ft) (ft) (els) (els) I from Inlet# (els) (els) (ft) I (I n)
8.17 10 12 .00 I 12 .00 13 .20 0.6261 7.51
1.51 I 1.51 1.66
*using y....,.. • 1· • 0.583'
100 y ear sto rm
OupMod 010-Total Y100 a,.,,oot Oupaclty Obypan O c.,tured Oc.,ryo .... r Ottyp-tot .. Ocapl-tod 0 100·To1.i s L.c:1ua1
(els) (els) (ft) I (In) (ft) (els) (els) (els) (cfs) J from inl•t fl. (els) (els) (els) (ft/ft) (ft)
1.77 1.77 o.243 I 2.92 0.54 2.71 -0 .32 2.39 I 0.00 2.39 2.39 0.0100 5 ---------
4.75 4.75 o.352 I 4.22 0.64 6.45 ·0.05 6.40 I 0.00 6.40 6.40 0.0100 10
APPENDIXC
Storm Pipe Design Data & Calculations (Revised)
I S
South Hampton Subdivision -Phase 3
p· C I I R d J I 20 4 1pe a cu at1ons -ev1se u 'Y 0
Inlet O utl et
Pipe# S iz e L ength S l o pe
Invert Elev Invert Elev
(in) (ft) (%) (ft) (ft)
1A 27 50 .9 1.40 255 .88 255 .17 --
18 27 232.6 1.40 259.24 255.98 -
2 27 38.5 1.20 259.80 259 .34 -
3 27 6 .0 1.00 260 .26 260 .20
*Actual Flow
(cfs)
-
-
-
-
10 yea r s t o rm 1 00 year s t o rm
Desig n Fl ow V 10 Travel Time, tno *Actual Fl ow Design Flow V100 %F ull %F ull
(cfs) (fps ) (sec) (m in) (cfs ) (cfs ) (fps )
25 .14 9.4 63 .9 5 0.09 -33 .99 9.8 81.9
25.14 9.4 63 .9 25 0.41 -33 .99 9.8 81 .9
2 3 .37 8 .7 64 .1 4 0 .07 -31 .60 9 .0 82 .2
18 .62 7 .7 58.6 1 0 .01 -25 .1 5 8.2 72.4
*These valu es reflect the actual flow for the 18" & 24" pipes . The design fl ow for th ese pip e sizes refle cts a 2 5 % redu ction in pipe area.
Pipe 3 Culvert Calcu lator Data :
Tailwater = 2 .25 ft
Top of Road = 264.50
Headwater, 10-year = 262 .99
Headwater, 100-year = 263.43
Travel Time, tn00
(sec) (min)
5 0 .09
24 0.40
4 0.07
1 0 .01
-
South Hampton S ubdivi s ion
Phase 3 -Pipe Flo w Diagram
Revis ed July 2004
010 {cf s) I
Dra in age A reas 1+2 18 .62
J,
Pipe 3 18.62
J,
Inlet 2 4 .75
J,
Pipe 2 23 .37
J,
Inlet 1 1.77
J,
P ipe 18 25 .14
J,
Junction Bo x 1
J,
Pipe 1A 25 .14
J,
Existing Inle t 9 .92
II Into Existi ng Pi pe 35 .0 6 II
0100 {c fs) I
Dra inage Areas 1+2 25 .15
J,
Pipe 3 25.15
J,
Inlet 2 6.45
J,
Pipe 2 31 .60
J,
Inlet 1 2.39
J,
Pipe 1 B 33 .99
J,
Jun ctio n Bo x 1
J,
Pip e 1A 33 .99
J,
Exis ting Inlet 13.5 1
Into Ex isting Pipe 47.50 II
Pipe lA -10 Ye ar 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
27.0000 in
25.1400 cfs
0 .0140 ft/ft
0. 0140
17.2655 in
3.9761 ft2
2.6848 ft2
50.0438 in
84.8230 in
9.3638 fps
7.7255 in
63.9464 %
34 .0271 cfs
8.5580 fps
Pipe lA -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 ...................... .
Vel ocity ....................... .
Hydraulic Rad i u s ............... .
Percent Full ................... .
Full flow Fl owrate ............. .
Full flow veloci t y ............. .
Circular
Depth of Flow
27.0000 in
33.9900 cfs
0. 0140 ft/ft
0. 0140
22.1032 in
3.9761 ft2
3.4841 ft2
61 .067 3 in
84 .8230 in
9.7558 fps
· 8 .21 57 i n
81.8636 %
34.0271 cfs
8.5580 fps
South Ha mpton S u bd i vision -Ph ase 3 -Revised July 2004
College Stati o n, Texas
Pipe lB -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Comp ute d Results:
Depth .......................... .
Area ........................... .
Wette d Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
2 7 .0000 in
25 .1400 cfs
0.0140 ft/ft
0. 0140
17.2655 in
3.9761 ft2
2.6848 ft2
50 .0438 in
84 .8230 in
9.3638 fps
7 .7255 in
63.9464 %
34.0271 cfs
8.5580 fps
Pipe lB -100 Year Storm
Manning Pipe Calculator
Gi ven Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Ve loc ity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow ve loc ity ............. .
Circular
Depth of Flow
27.0000 in
33 .9900 cfs
0 .0140 ft/ft
0. 0140
22.1032 in
3.9761 ft2
3.4841 ft2
61.0673 in
84.8230 in
9.7558 fps
8 .2157 in
81.863 6 %
34.0 27 1 c f s
8 .5 580 fps
South Hampt on Su bdi visio n -Phas e 3 -Revised July 20 04
College S t atio n, Texas
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 Radiu s ............... .
Percent Full ................... .
Full flow Flowrat e ............. .
Full flow velocity ............. .
Circular
Depth of Flow
27.0000 in
23 .3700 cfs
0 .01 2 0 ft/ft
0 .0140
17 .314 1 in
3.9761 ft2
2.6935 ft2
50 .1450 in
84.8230 in
8.6763 fps
7.7 350 in
64.1262 %
31.5030 cf s
7.9231 fps
Pipe 2 -100 Year Storm
Manning P i pe Calculator
Given Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
We tted Perimeter ............... .
Perime t er ...................... .
Veloci t y ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
27.0000 in
31.6000 cfs
0 .0120 ft/ft
0.0140
22.2066 in
3.9761 ft2
3.4990 ft2
61.3366 in
84.8 230 in
9.0313 fps
8.2145 in
82.2465 %
31.5030 cfs
7.9231 fps
South Ha mp ton Subdivision -Ph ase 3 -Re vised July 20 04
College Station, Tex as
Pipe 3 -10 Year Sto rm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrat e ....................... .
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
27 .0000 in
18 .6200 cfs
0 . 0100 ft/ft
0.0140
15.8169 in
3.9761 ft2
2.4203 ft2
47.0684 in
84 .8230 in
7.6932 fps
7.4047 in
58.5812 %
28.7581 cfs
7.2328 fps
Pipe 3 -100 Year Storm
Manning Pipe Calculator
Giv en Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wett e d Perime t e r ............... .
Perimet e r ...................... .
Velo c ity ....................... .
Hydraulic Ra diu s ............... .
Percent Full ................... .
Full fl ow Flowra te ............. .
Full fl ow ve l oc ity ............. .
Circular
Depth of Flow
27.0000 in
25.1500 cfs
0.0100 ft/ft
0.0140
19 .5576 in
3 .9761 ft2
3.0845 ft2
54 .9753 in
84.8 23 0 in
8 .15 3 7 fps
8 .07 9 4 in
72 .43 56 %
2 8 .7581 cf s
7 .232 8 fps
South Ha mpton Subdivision -Ph ase 3 -Revised Jul y 2004
College S ation, Texas
Entered Dat a:
Pipe 3 -10 Year Storm
Culv ert Calculator
Shape .......................... .
Number of Barrels .............. .
Solving for ................. .
Chart Number ................ .
Scale Number ................ .
Chart Description .............. .
Scale Description .............. .
Overtopping .................... .
Flowrate ....................... .
Manning ' s n .................... .
Roadway Elevation ............. , .
Inlet Elevation ................ .
Outlet Elevation ............... .
Diamete r ....................... .
Length ......................... .
Entrance Loss ............. .
Tailwater ........... .
Computed Results :
Headwater ...................... .
Slope .......................... .
Velocity ....................... .
Circular
1
Headwater
1
1
CONCR ETE P I PE CUL VERT ; NO BEVE LED RI NG ENTRANCE
SQ UA RE EDG E ENTRAN CE WITH HEADWA LL
Off
18.6200 cfs
0 . 0140
264.5000 ft
260 .2600 ft
260 .2 000 ft
27.0000 in
6.0000 ft
0 .5000
2 .2500 ft
262.9862 ft Outlet Control
0.0100 ft/ft
4.6830 fps
Pipe 3 -10 0 Year Storm
Culvert Calculator
Entered Data :
Shape .......................... .
Number of Barrels .............. .
Solving for .................... .
Chart Number ................... .
Scale Number ................... .
Chart Description .............. .
Scale Description .............. .
Overtopping : ................... .
Flowrate ....................... .
Manning ' s n .................... .
Roadway El evation .............. .
Inle t Elevation .............. .
Outl et Elevation ............... .
Diameter ................. .
Length .................... .
Entrance Loss ............ .
Tailwater ................ .
Computed Results:
Headwater ...................... .
S lop e .......................... .
Velocity ....................... .
Ci rcul ar
1
Headwater
1
1
CONCR ETE PIPE CULVERT; NO BEVELED RING ENTRANCE
SQUARE EDGE ENTRANCE WITH HEADWA LL
Off
25.1500 cfs
0. 0140
264.5000 ft
260.260 0 ft
260 .2000 ft
27.0000 in
6 .0000 ft
0 .5000
2.2500 ft
263.4283 ft Outl et Co ntrol
0.0100 ft/ft
6 .32 53 fps
South Hampton Subdivision -Ph ase 3 -Revised July 2004
College Station, Texas
EXHIBIT A
Post-Development Drainage Area Map (Revised)
22
I
DEVELOPMENT PERMIT
PERMIT NO. 04-22 c.·w Project: SOUTH HAMPTON PHASE 3
COLLE<;[ STATION FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA
RE : CHAPTER 13 OF THE COLLEGE STATION CITY CODE
SITE LEGAL DESCRIPTION:
South Hampton Phase 3
All Lots
DATE OF ISSUE: 07/19/04
OWNER:
Nantucket , Ltd . -Phyllis Hobson
1101 University Drive East, Suite 108
College Station , Texas 77840
SITE ADDRESS:
SH 6 South
DRAINAGE BASIN:
Alum Creek
VALID FOR 9 MONTHS
CONTRACTOR:
TYPE OF DEVELOPMENT: Full Development Permit
SPECIAL CONDITIONS:
All construction must be in compliance with the approved construction plans
All trees required to be protected as part of the landscape plan must be completely barricaded in accordance with Section
7.5.E ., Landscape/Streetscape Plan Requirements of the City's Unified Development Ordi ance , prior to any operations of
this permit. The cleaning of equipment or materials within the drip line of any tree or group of trees that are protected and
required to rema in is strictly prohibited . The disposal of any waste material such as , but not limited to , paint , oil , solvents ,
asphalt , concrete , mortar, or other harmful liquids or materials within the drip line of any tree required to remain is also
prohibited .
TCEQ PHASE II RULES IN EFFECT.
The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate construction site
in accordance with the approved erosion control plan as well as the City of College Station Drainage Policy and Design
Criteria . If it is determined the prescribed erosion control measures are ineffective to retain all sediment onsite , it is the
contractors responsibility to implement measures that will meet City , State and Federal requirements . The Owner and/or
Contractor shall assure that all disturbed areas are sodden and establishment of vegetation occurs prior to removal of any
silt fencing or hay bales used for temporary erosion control. The Owner and/or Contractor shall also insure that any
disturbed vegetation be returned to its original condition , placement and state . The Owner and/or Contractor shall be
responsible for any damage to adjacent properties , city streets or infrastructure due to heavy machinery and/or equipment
as well as erosion , siltation or sedimentation resulting from the permitted work.
In accordance with Chapter 13 of the Code of Ordinances of the City of College Station , measures shall be taken to insure
that debris from construct ion , erosion , and sedimentation shall not be deposited in city streets, or existing drainage
facilit ies .
I hereby grant th is permit for development of an area outside the special flood hazard area . All development shall be in
accordance with the plans and specifications submitted to and approved by the City Engineer in the development permit
application for the above named project and all of the codes and ordinances of the City of College Station that apply.
0 7-/?J-o t/
Date
7-/1 -ef
Date
Item
No .
2
3
4
5
Water Lines
Mobilization/Layout
ENGINEER'S COST ESTIMATE
SOUTHHAMPTON-PHASE 1
EXTEND WATERLINE TO PHASE 3
COLLEGE STATION , TEXAS
Estimated
Description Quantity
LS
28-May-0 4
Unit Estimated
Price Cost
$500.00 $500
6" Water PVC CL200 (C909) structural 74 LF $26 .00 $1,924
6" M .J. Bends
2" Blow off Assembly
Tie-in to existing line
1 EA $250 .00 $250
EA $400.00 $400
EA $200.00 $200
Subtotal $3,274
T OT A L CO NSTRUCTION ._I __ $-'-3...:..,2_7__.41
TOTA L ~I __ $3~,2_7~4 1
Item
No .
2
3
4
5
Water Lines
Mobi lization/Layout
ENGINEER'S COST ESTIMATE
SOUTHHAMPTON-PHASE1
EXTEND WATERLINE TO PHASE 3
COLLEGE STATION , TEXAS
Estimated
Description Quantity
LS
28-May-04
Unit Estimated
Price Cost
$500 .00 $500
6" Water PVC CL200 (C909) structural 74 LF $26 .00 $1,924
6" M .J. Bends
2" Blow off Assembly
Tie-in to existing line
Page 1 o r 1
EA $250.00 $250
EA $400 .00 $400
EA $200 .00 $200
Subtotal $3,274
TOTAL CONSTRUCTION._! __ $_3-'-,2_7~41
TOTA Ll~ __ $3_,2_7~4'
Item
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
CONSTRUCTION COST ESTIMATE
SOUTH HAMPTON SUBDIVISION
COLLEGE STATION, TEXAS
PHASE 3 • 11 LOTS
Description
Sitework
Mobilization/Layout
Site Preparation -ROW & easements
Silt Fence
Construction Exit-Rock
Hydromulch /Hydroseeding
Tie-in to existing pavement I 6' sid ewalk
Topsoil Stripping & Replacement
Excavation/Grading
Lime Stabilized Subgrade
Asphalt Paving -1 1/2" depth
Base Material -6" depth
Concrete Curb and Gutter
Concrete Aprons
ADA Ramp -corner
Concrete Sidewalk
End of Roadway Sign -red/black
Storm Drainage
Drainage Pipe -27" RCP, T & G -structural
Drainage Pipe -27" RCP , T & G -non-structural
Junction Box
Inlets 5' wide
Inlets 1 O' wide
Inlet Protection
Concrete Flume
Headwall -27" RCP
Remove existing headwall (for 24" pipe), 24" RCP & Cone . Flume
Water Lines
6" Water PVC CL200 (C909) non-structural
6" Water PVC Cl200 (C909) structural
3" Water PVC CL200 -non-structural
3" Water PVC CL200 -structural
6" Gate Valves
3" Gate Valves
6" x 3" M .J. Tees
6" 11 .25 deg . M .J . Bend
6" 22.50 deg . M .J . Bend
1" Blowoff Assembly
2" Blowoff Assembly
Fire Hydrant Assembly
Fire Hydrant Vertical Extens ion
Restrain ed Joint -6"
Tie-in to existing line
Water Services
Page 1 of 1
Estimated
Quantity
1.1
300
20
2,000
1
250
650
1,950
1,585
1,585
973
498
2
1,400
3
65
289
1
1
1
3
60
1
201
42
100
72
1
1
1
1
2
1
3
1
.6
20
130
4
1
2
LS
AC
LF
TONS
SY
LS
CY
CY
SY
SY
SY
LF
SF
EA
SF
EA
LF
LF
EA
EA
EA
EA
SF
EA
LS
LF
LF
LF
LF
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Unit
Price
$4,500.00
$5,500.00
$2 .50
$50 .00
$0 .50
$500 .00
$5.00
$4 .00
$3 .10
$5.25
$6.00
$7 .75
$5 .50
$450.00
$2.80
$200.00
Subtotal
$50.00
$42 .00
$2,500.00
$2,600 .00
$3,100 .00
$100 .00
$5.00
$2,000 .00
$1,000 .00
Subtotal
$20 .00
$28 .00
$15 .00
$20.00
$550.00
$400 .00
$250 .00
$250 .00
$250 .00
$350 .00
$400 .00
$2,250 .00
$200 .00
$175 .00
$100 .00
$700.00
Subtotal
LF $30.00
LF $22 .00
EA $700 .00
EA $800 .00
EA $800 .00
EA $2,400 .00
EA $1,000.00
Subtotal
08-Jul-04
Estimated
Cost
$4 ,500
$6 ,050
$750
$1 ,000
$1 ,000
$500
$1,250
$2,600
$6,045
$8,321
$9 ,5 10
$7,541
$2 ,739
$900
$3,920
$600 .00
$57 ,226
$3 ,250
$12, 138
$2,500
$2,600
$3 ,100
$300
$300
$2 ,000
$1,000
$27 ,188
$4,020
$1, 176
$1 ,500
$1,440
$550
$400
$250
$250
$500
$350
$400
$2 ,250
$200
$525
$100
$4,200
$18,111
$600
$2,860
$2 ,800
$800
$1 ,600
$2,400
$1,000
$12,060
Total Sitework $57,226
Total Storm Drainage $27, 188
Total Water $18, 111
Total Sanitary Sewer $12 ,060
TOTAL CONSTRUCTION'! --...,.$1_1_4~,5...,.8...,51
Item
No .
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
CONSTRUCTION COST ESTIMATE
SOUTH HAMPTON SUBDIVISION
COLLEGE STATION , TEXAS
PHASE 3 -11 LOTS
Description
Sitework
Mobilization/Layout
Site Preparation -ROW & easements
Silt Fence
Construction Exit-Rock
Hydromulch/Hydroseeding
Tie-in to existing pavement I 6' sidewalk
Topsoil Stripping & Replacement
Excavation/Grading
Lime Stabilized Subgrade
Asphalt Paving -1 1/2" depth
Base Material -6" depth
Concrete Curb and Gutter
Concrete Aprons
ADA Ramp -corner
Concrete Sidewalk
End of Roadway Sign -red/black
Storm Drainage
Drainage Pipe -27" RCP, T & G -structural
Drainage Pipe -27" RCP , T & G -non-structural
Junction Box
Inlets 5' wide
Inlets 10' wid e
Inlet Protection
Concrete Flume
Headwall -27" RCP
Remove existing headwall (for 24" pipe), 24" RCP & Cone . Flum e
Water Lines
6" Water PVC CL200 (C909) non-structural
6" Water PVC CL200 (C909) structural
3" Water PVC CL200 -non-structural
3" Water PVC CL200 -structural
6" Gate Valves
3" Gate Valves
6" x 3" M.J . Tees
6" 11.25 deg . M .J . Bend
6" 22 .50 deg . M .J. Bend
1" Blowoff Assembly
2" Blowoff Assembly
Fire Hydrant Assembly
Fire Hydrant Vertical Exten sio n
Restrained Joint -6"
Tie -in to existing lin e
Water Services
Page 1 o f1
Estimated
Quantity
1.1
300
20
2,000
1
250
650
1,950
1,585
1,585
973
498
2
1,400
3
65
289
1
1
1
3
60
1
1
201
42
100
72
1
1
1
1
2
1
3
1
6
20
130
4
1
2
LS
AC
LF
TONS
SY
LS
CY
CY
SY
SY
SY
LF
SF
EA
SF
EA
LF
LF
EA .,
EA
EA
EA
SF
EA
LS
LF
LF
LF
LF
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Unit
Price
$4,500 .00
$5 ,500 .00
$2 .50
$50.00
$0 .5 0
$500 .00
$5 .00
$4 .00
$3 .10
$5.25
$6 .00
$7 .75
$5 .50
$450.00
$2 .80
$200 .00
Subtotal
$50 .00
$42 .00
$2 ,500 .00
$2,600 .00
$3, 100 .00
$100.00
$5 .00
$2,000 .00
$1 ,000 .00
Subtotal
$20 .00
$28 .00
$15 .00
$20 .00
$550 .00
$400 .00
$250.00
$250.00
$250.00
$350 .00
$400 .00
$2,250 .00
$200 .00
$175 .00
$100 .00
$700 .00
Subtotal
LF $30 .00
LF $2 2.00
EA $700 .00
EA $800 .00
EA $800 .00
EA $2,400 .0 0
EA $1 ,000 .00
Subtotal
08-Jul-04
Estimated
Cost
$4,500
$6,050
$750
$1,000
$1 ,000
$500
$1,250
$2,600
$6,045
$8,321
$9,510
$7,541
$2 ,739
$900
$3,920
$600 .00
$57,226
$3 ,250
$12,138
$2 ,500
$2,600
$3 , 100
$300
$300
$2 ,000
$1 .000
$27,188
$4,020
$1, 176
$1,500
$1,440
$550
$400
$250
$250
$500
$350
$400
$2,250
$200
$525
$100
$4,200
$18,111
$600
$2,860
$2 ,800
$800
$1 ,6 00
$2,400
$1,000
$12,060
Total Sitework $57,226
Total Storm Drainage $27,188
Total Water $18 ,111
Total Sanitary Sewer ,-----__ ,...::$....:.1=2•c:.O.:c.60.:.,
TOTAL CONSTRUCTION._! __ _,_$_11_4_,__,5_8 _,5j
Item
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
CONSTRUCTION COST ESTIMATE
SOUTH HAMPTON SUBDIVISION
COLLEGE STATION, TEXAS
PHASE 3 -11 LOTS
Description
Sitework
Mobilization/Layout
Site Preparation -ROW & easements
Silt Fence
Construction Exit-Rock
Hydromulch/Hydroseeding
Tie-in to existing pavement I 6' sidewalk
Topsoil Stripping & Replacement
Excavation/Grading
Lime Stabilized Subgrade
Asphalt Paving -1 1/2" depth
Base Material -6" depth
Concrete Curb and Gutter
Concrete Aprons
ADA Ramp -corner
Concrete Sidewalk
End of Roadway Sign -red/black
Storm Drainage
Drainage Pipe -27" RCP, T & G -structural
Drainage Pipe -27" RCP, T & G -non-structural
Junction Box
Inlets 5' wide
Inlets 10' wide
Inlet Protection
Concrete Flume
Headwall -27" RCP
Remove existing headwall (for 24" pipe), 24" RCP & Cone. Flume
Water Lines
6" Water PVC CL200 (C909) non -s tructural
6" Water PVC CL200 (C909) structural
3" Water PVC CL200 -non-structural
3" Water PVC CL200 -structural
6" Gate Valves
3" Gate Valves
6" x 3" M.J . Tees
6" 11.25 deg. M.J . Bend
6" 22.50 deg . M.J. Bend
1" Blowoff Assembly
2" Blowoff Assembly
Fi re Hydran t Assembly
Fire Hydrant Vertical Extension
Restrained Joint -6"
Tie-in to existing lin e
Water Services
Estimated
Quantity
1
1.1
300
20
2,000
1
250
650
1,950
1,585
1,585
973
498
2
1,400
3
65
289
1
1
3
60
1
1
201
42
100
72
1
1
2
1
1
1
1
3
1
6
20
130
4
1
2
LS
AC
LF
TONS
SY
LS
CY
CY
SY
SY
SY
LF
SF
EA
SF
EA
LF
LF
EA
EA
EA
EA
SF
EA
LS
LF
LF
LF
LF
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
EA
Unit
Price
$4,500 .00
$5 ,500 .00
$2.50
$50 .00
$0.50
$500.00
$5.00
$4 .00
$3.10
$5.25
$6 .00
$7 .75
$5 .50
$450 .00
$2 .80
$200.00
Subtotal
$50 .00
$42 .00
$2,500.00
$2,600 .00
$3,100 .00
$100.00
$5.00
$2,000.00
$1,000.00
Subtotal
$20.00
$28.00
$15.00
$20.00
$550.00
$400.00
$250.00
$250.00
$250 .00
$350 .00
$400.00
$2 ,250.00
$200 .00
$175 .00
$100.00
$700 .00
Subtotal
LF $30 .00
LF $22 .00
EA $700 .00
EA $800 .00
EA $800 .00
EA $2,400 .00
EA $1 ,000.00
Subtotal
08-Jul-04
Estimated
Cost
.$4,500
$6,050
$750
$1,000
$1,000
$500
$1,250
$2,600
$6,045
$8,321
$9,510
$7,541
$2,739
$900
$3,920
$600 .00
$57,226
$3,250
$12,138
$2,500
$2,600
$3,100
$300
$300
$2,000
$1,000
$27,188
$4,020
$1,176
$1,500
$1,440
$550
$400
$250
$250
$500
$350
$400
$2,250
$200
$525
$100
$4,200
$18,111
$600
$2 ,860
$2 ,800
$800
$1,600
$2,400
$1,000
$12,060
Total Sitework $57,226
Total Storm Drainage $27,188
Total Water $18,111
Total Sanitary Sewer $12,060
TOTAL CONSTRUCTION 'I ---,.-$~11-4~,5...,,.B-,5 I
Drainage Report
for
South Hampton Subdivision
Phase 3
College Station, Texas
May 2004
Developer:
Nantucket, Ltd.
1101 University Drive East, Suite 108
College Station, Texas 77840
Prepared By:
TEXCON General Contractors
1 707 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 Phase 3 of the South Hampton Subdivision in College Station, Texas , was
prepared by me in accordance with the provisions of the City of College Station Drainage Policy and
Design Standards for the owners hereof, with the exception that stom1 water runoff detention is not
being required for this project since it was determined during the development of Phase 1 of the
subdivision that the site discharges directly into the TxDOT stom1 drainage system, which discharges
into a tributary of Alum Creek. This tributary is a part of the Alum Creek primary system , which is a
part of the Lick Creek drainage basin. Nantucket Lake serves as a detention facility for the Alum
Creek drainage basin, and with the South Hampton runoff discharging into this primary system
downstream of the lake, the South Hampton peak runoff will have already passed before the peak
discharge at Alum Creek, therefore resulting in no increase in the peak runoff in Alum Creek.
TABLE OF CONTENTS
SOUTH HAMPTON SUBDIVISION -PHASE 3
CERTIFICATION .................................................................................................................................................................. 1
TABLE OF CONTENTS ........................................................................................................................................................ 2
LIST OFT ABLES .................................................................................................................................................................. 2
INTRODUCTION ................................................................................................................................................... ~ ............... 3
GENERAL LOCATION AND DESCRIPTION .................................................................................................................. 3
FLOOD HAZARD INFORMATION .................................................................................................................................... 3
DEVELOPMENT DRAINAGE PATTERNS ....................................................................................................................... 3
DRAINAGE DESIGN CRITERIA ........................................................................................................................................ 3
STORM WATER RUNOFF DETERMINATION ............................................................................................................... 5
STORM SEWER DESIGN .................................................................................................................................................... 5
STORM DETENTION ........................................................................................................................................................... 6
CONCLUSIONS ..................................................................................................................................................................... 6
APPENDIX A .......................................................................................................................................................................... 7
Time of Concentration Data & Calculations
APPENDIX B ........................................................................................................................................................................ 11
Storm Inlet Design Data & Calculations
APPENDIX C ........................................................................................................................................................................ 14
Storm Pipe & Channel Design Data & Calculations
EXHIBIT A ............................................................................................................................................................................ 21
Post-Development Drainage Area Map
LIST OF TABLES
TABLE 1 -Rainfall Intensity & Runoff Data .................................................................................................... 4
TABLE 2 -Time of Concentration (tc) Equations ............................................................................................ .4
TABLE 3 -Post-Development Drainage Data .................................................................................................... 5
DRAINAGE REPORT
SOUTH HAMPTON SUBDIVISION -PHASE 3
INTRODUCTION
The purpose of this report is to provide the hydrological effects of the construction of Phase 3
of the South Hampton Subdivision, and to show that the storm water runoff will be controlled
in such a manner so as to have minimal offsite or downstream impact.
GENERAL LOCATION AND DESCRIPTION
The project is located on a 4 acre tract located in College Station, Texas . The site is wooded
with areas of open land with grass. The existing ground elevations range from e levation 261 to
elevation 273. 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 Alum Creek Drainage Basin , which is a part of the Lick Creek
Drainage Basin . No portion of the site is located in a Special Flood Hazard Area according to
the Flood Insurance Rate Map (FIRM) prepared by the Federal Emergency Management
Agency for Brazos County, Texas and incorporated areas dated February 9, 2000, panel
number 48041 C0205-D.
DEVELOPMENT DRAINAGE PATTERNS
Prior to development, storm water runoff from the site generally flows in a northerly direction.
A majority of the runoff flows into an existing concrete flume and then into the existing storm
system, which ties into the storm drainage system in the State Highway 6 right-of-way . A
small portion of the runoff flows in a northwesterly direction where it enters the Nantucket
Drive right-of-way. After development, these flow patterns will typically remain the same ,
however, the water captured by the existing flume will be diverted through the proposed storm
system, which ties into a new concrete flume before discharging into the existing flume and
storm drainage system. This system ultimately discharges into Alum Creek. The post-
development drainage area boundaries are shown on Exhibit A .
DRAINAGE DESIGN CRITERIA
The desi gn para meters for the storm sewer are as follows :
• The Rational Method is utili zed to d e te m1in e peak stonn wate r run off ra tes fo r the
s tom1 sewer d esign.
• Des ign Storm Freque ncy
Stom1 sewer syste m
• R un off Coeffic ie nts
S in g le Fa mil y R es id enti a l
Und eve lo ped
10 a nd 100-year s to rm eve nt s
c = 0 .50
c = 0.30
• Ra in fa ll Int e nsity equ a ti o ns a nd va lues ror Braws County ca n be fou nd in Table I.
• Tim e or Co nce ntr a ti o n, le -Ca lc ulatio ns a rc ba se d O il the rn e lhocl round in th e TR-55
publicatio n. Rere r to Tab le 2 lo r th e equ ation s a nd Appendi x A ro r ca lc ul at io ns. T he
runoff flow paths used for c a lculating the time s o f concentration are shown in Ex hibit
A. For smalle r drainage areas , a minimum tc of 10 minutes is use d to d e termin e th e
rainfall intensity value s .
TABLE 1 -Rainfall Intensity & Runoff Data
Rainfall Intensity Values
(in/hr)
Storm
Event
Is
110
'2s
lso
1100
Brazos
County:
tc =
10 min
7.693
8 .635
9.861
11 .148
11 .639
I = b I (tc+d)e
I = Rainfall Intensity (in/hr)
tc = U(V*60)
le= Time of concentration (min)
L = Length (ft)
V =Velocity (ft/sec)
5 Y..ear storm 10 'f..ear storm 25 'i.ear storm 50 'i.ear storm 100 'f..ear 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 Hiqhwa'f..S and Public Transportation HY..draulic Manual, page 2-16)
TABLE 2 -Time of Concentration (tc) Equations
Th e time of concentration was d etermined using methods found in TR -55 , "Urban
Hy drology for Small Wat ersh eds . " The equations are as follows :
Time of Concentration:
For S hee t F lo w:
Fo r S ha ll ow Conce nt ra te d Fl ow :
Re fe r to A pp e nd ix A fo r ca lc ul a ti o ns.
Tc = T t(sheet flow)+ T t(concentrated sheet fl ow )
where: T1 =Travel Time, minutes
w he re : T 1 =trave l tim e, hours
n =M anni n g's ro ugh ne ss coeffic ie nt
L = fl ow le n gth , fee t
P2 = 2-yea r , 24 -h our ra in fa ll = 4.5''
s = la nd s lo pe, ft /ft
T 1 = L I (60 *V)
w he re: T 1 =tra ve l t ime, m in ut e s
V =Ve loc ity , fps (See Fig 3-1, App. E)
L = n ow lengt h , fee t
ST O RM WATE R R UN O FF D ETERM l NATlON
The p eak runoff val ues were d e t e 1mine d in acco rdance w it h the criteria presente d in th e
prev ious section for th e 5, 10 , 25 , 50, and 100-y ear sto tm events . The runoff coeffic ients
for po s t-d eve lopm e nt calculations are b ased on th e future d eve lo pm e nt of this trac t , a nd the
p eak runoff values d e termined for th e po s t -deve lopment condition are s hown in Tabl e 3.
TABLE 3 -Post-D eve lopme n t Dra inage Data
5 y ear sto rm 10 year sto r m 25 y ear sto rm 50 y ear storm 100 year sto rm
Area le A rea# c Is O s •10 Q 10 l2s 0 2s lso O so •100 0 100
(acres) (min) (i n/hr) (cfs) (in/hr) (c f s) (in/h r) (cfs) (in/h r) (cfs) (in/hr) (cfs)
1 3.83 0 .50 13.4 6 .739 12 .90 7 .592 14 .54 8 .684 16.63 9.831 18 .83 10 .258 19 .64
2 1.14 0 .50 10.8 7.441 4 .24 8.360 4 . 77 9.552 5.44 10.802 6 .1 6 11.276 6.43
3 0.5 8 0 .50 10 7.693 2.23 8.635 2. 50 9 .861 2.86 11 .148 3 .23 11 .6 39 3.38
4 0 .52 0.50 10 7 .693 2.00 8 .635 2. 24 9.861 2.56 11 .148 2 .90 11 .639 3.03 --
5 0.41 0 .50 10 7 .693 1.58 8 .63 5 1. 77 9 .861 2.02 11 .148 2 .29 11 .639 2 .39
6 0 .73 0.50 10 7 .693 2 .81 8.635 3 . 15 9 .861 3.60 11 .148 4 .07 11 .639 4 .2 5
The post-d eve lopm e nt drainage areas are shown on Exhibit A. Even thoug h the runoff
coefficient for the developed conditions increases the runoff, the storm sewer system
conveys th e runoff directly to a tributary of A lum Creek.
STO RM SEWER D ESIGN
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. The curb inlets will be
cast-in-place concrete. Appendix B presents a summary of the storm sewer inl e t design
parameters and calculations. The inlets were designed based on a I 0-year design storm.
As per College Station g u idelines, t he capacities of inlets in sump were reduced by 10% to
allow for clogging.
Inlets were located to maintain a gutter flow depth of 5" or less , which 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 at various locations . The runoff
intercepte d by the proposed storm sewer inlets was calcul ated using the following
equ a tions . T he depth of flow in the g utt er was d etermined by u s ing th e Straight Crown
F low e quation . The flows interce pte d b y Inl e ts I & 2 were calc ul ated by u si n g the
Capac it y of Inlets On Grade e qu a tion. T h ese e qu atio n s and the resu ltin g data are
sum m a ri zed in A ppend ix B . There are no inl ets in s ump for this phase of th e d e velopment .
Th e a rea b e tween th e ri g h t-of-way and th e c urb li ne of the streets w ill b e fi ll ed as
necessary to provid e a minimum of 6" of freeboard above th e c urb lin e. T hi s wil l e ns ure
that th e runoff from the 100-year sto 1111 eve nt will re ma in within th e s treet ri g ht -o f-wa y.
Appe ndi x C prese nt s a s ummary of th e s to rm sewe r pipe d es ig n p a ra m e te rs a nd
c al c ul ations. A ll pip es are 18" in di a m e te r o r larger. T h e pip es for th e s to rm sewe r sys te m
were d es ig n e d ba sed on th e I 0-ycar s to rm eve nt ; h oweve r , a ll wil l a lso p ass th e I 00-ycar
s to rm eve nt w ith o ut any h eadwa te r . As re q uir e d b y C o ll ege S ta tion , th e ve loc it y o f n ow in
th e s torm sewe r p ip e sys te m is no t lower than 2.5 fee t p e r seco nd , a nd it d ocs no t exceed
15 feet p er seco nd . As th e d a ta s hO\\S, evc 11 durin g low !l ow co ndition s, th e ve loc it y in th e
pip es and boxe s w ill exceed 2 .5 fee t pe r seco nd and pre ve 11l scdi111 e 11t bui ld -up in t he pip es
and boxes. The maximum flow in the stom1 sewer pipe system will occur in Pip e l.
Appendi x C contai ns a summary of th e Manning pipe calcul ations for th e s tom1 sewe r
system for the I 0 and 100-year eve nts . The maximum ve locit y for the pipe system wi ll be
9 .0 feet p er seco nd and will occur in Pip e 2.
The stom1 sewer pipe system discharges into a drainage channel which will ha ve a 5 '
concrete flume to prevent e rosion of th e flow line of the chann e l. The propos ed c ha nn e l is
a "v" shaped channel with 4H : 1 V side s lopes. It will be constructed at a s lop e of0.63 %,
and it will carry 7 cfs of flow before the depth of the flow exceeds the concrete flume
height. This is approximately 25% of the 10-year storm event (29 cfs). The d ept h a nd
velocity of flow in the channel for the 10-yea r storm eve nt are 16 .9" and 3.7 fps , a nd the
depth and ve locity of flow for the 100-year storm event are 18 .9" and 3.9 fps . To furth e r
prevent erosion of the channel, grass sod wi ll be used to lin e the channel banks to a
minimum depth of 1.5 feet, which is greater than the 10-year storm flow depth . The
channel will be constructed with a minimum depth of 2.5 feet to restrict the flow to th e
drainage easement. The proposed channel discharges into an existing drainage channel
that also has a concrete flume .
STORM DETENTION
The storm water runoff detention is not being required for this project since it was
determined during the development of Phase 1 of the subdivision that the site discharges
directly into the TxDOT stonn drainage system, which discharges into a tributary of Alum
Creek. This tributary is a part of the Alum Creek primary system, which is a part of the
Lick Creek drainage basin. Nantucket Lake serves as a detention facility for the Alum
Creek drainage basin, and with the South Hampton runoff discharging into this primary
system downstream of the lake, the South Hampton peak runoff will have already passed
before the peak discharge at Alum Creek, therefore resulting in no increase in the peak
runoff in Alum Creek.
CONCLUSIONS
The construction of this project will increase the storm water runoff from this site, however
it should not have a significant impact on the surrounding property. No flood damage to
downstream or adjacent landowners is ex pected as a result of this dev e lopm ent.
7
APPENDIX A
Time of Concentration Data & Calculations
Time of Concentration Calculations
Refer to Ex hibit A fo r flow p ath us ed for ca lcu lations.
Drainage Area #1:
Sh eet Flo w: Flow le ngth = 12 5 ' = L
S lo p e= 3 .7%
n = 0 .15 , short grass , prairie
P2 = 4 .5"
ti= 0.007 (0 .15 * 125)°8
( 4 .5)0·5 (0.03 7)04
ti= 0 .129 hours = 7 .7 minutes
Shallow Con centrated Flo w: Flow length = 535 ' = L
Slope= 2 .1%
Flum e Flo w:
Drainage Area #2:
Sheet Flow:
For unpaved surface at 2.1 %, Velocity (V) = 2 .3 fp s (see Fig. 3-1)
~ ti = 53 5 ' I (60 *2 .3) = 3 .9 minute s
Flow length = 355 ' = L
Slope = 2 .7%
For p a ved surface at 2 .7 %, Velocity (V) = 3 .3 fps (s ee Fig. 3-1)
ti = 3 55' I (60*3.3) = 1.8 minutes
T c = 7 .7 + 3 .9 + 1.8 = 13.4 minutes
Flow length = 125 ' = L
Slope = 3 .1%
n = 0 .15 , short grass , prairie
P2 = 4.5"
ti= 0.007 (0.15 * 125)°·8
( 4.5)0'5 (0 .031)0 '4
ti= 0 .138 hours= 8 .3 minute s
Sha llow Con cen tra ted Flow: F low len gth = 195 ' = L
S lope = 1.8 %
Fl ulll e Flow:
For unp aved s urface at 1.8%, Ve loc ity (V) = 2 .15 fp s (see Fig. 3-1)
t, = 19 5 ' I (60 *2.15) = 1.5 m inu te s
F low le ngt h = 200 ' = L
S lo pe = 2 .7 %
Fo r pa ved s urfa ce a t 2.7%, V e lo c it y (V) = 3.3 fp s (sec Fig. 3-1)
t, = 200 ' I (60 *3.3 ) = 1.0 m inutes
T , = 8.3 + 1.5 + 1.0 = I 0 .8 minutes
....
'+--....
'+-
cu a.
0 .-
VI
cu
VI
~
:::J
0 u
~ cu ...
"' 3:
3 .2
.50 -
.20 -
.10
.06
.04 -
. 02 -
.01 -
.005
I
1
j
' I
J
I
I
' ,
j ,
j .
b
q, , .... b,
..:.. q, ~ .:..I ~~ j
I
j
I
I
I
I
2
,
' .
'
I
4
,
I
J
I
i
)
I
I
6
,
j
,
I j
j
I
i
Ave ra ge ve l ocity , ft /sec
IJ
j
. . .
' I
I
I ,
I I
10
. . .
I
Fil(U"' 1 -1.-,\ver.il(c vcloci li e> for C'l imati n l( l r.ivcl time for 'hallow COnCenlr.iled Oow .
(2 l0-Vl-TR -55. Seco nd Ed .. June L98!il
I
20
APPENDIXB
Storm Inlet Design Data & Calculations
1 1
South Hampton -Phase 3
Depth of Flow in Street Gutter
Gutter A c Slope
Location (acres) (tuft)
-·------· -----------------
E1 0.52 0 .50 0 .0102 -----------·--
E2 0.58 0 .50 0 .0160 -----------
----------------
F1 1.10 0 .50 0 .0100
10-year storm
0 10 Y10-actual 0 100
(cfs) (ft) (in) (cfs)
---·-------
2.25 0 .2 37 2 .84 3.03
---
2 .50 0.227 2.72 3 .38 ---·--·----
----------------
4 .75 0 .3 15 3.78 6.40 -----------------------
F2 0.41 0 .50 -----·--
Transverse (Crown) slope (ft/ft)
for 27' streets = 0.0300
0.0100 1.77
--
0 .217 2.61
----
(6" max . for
· standard curb)
Straight Crown Flow (Solved to find actual depth of flow in gutter, y):
Q = 0 .56 * (z/n) * S 112 * ys13 Q y ={QI (0.56 * (z/n) * S112]}31s
n = Roughness Coefficient= 0 .018
S = StreeUGutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
z = Reciprocal of crown slope:
for 27' streets = 33
2 .39
100-yea r storm
Y 100
(ft) (in)
----
0 .265 3.18
---
0.253 3.04
-----
--------
0 .352 4.22 ---
0.243 2.92 ---
South Hampton
Phase 3
Inlet Length Calculati ons
In le ts O n Grade
In le t# Length
Flow from
Area#
I 5' 5
2 10' 3+4
y,.
(ft ) I (in)
0.217 I 2 .61
0 .315 3.78
1 O year storm
O p.,1001 Oupac:lti a by pan ac.lured <lc.arryooww
(ft) (els) (els) (els) (els) I from lnl•U
0.52 2 .59 -0 .82 1.77 I
0 .61 6 .09 -1 .34 4 .75 I
Transverse (C rown) slope (fVftl
for 27' streets ; 0 .030
z ; Re c iprocal of crown slope
for 27' streets ; 33
Straight C row n Flow (Solve d to find actual depth of flow, yl :
a; o .s6 • (z/n ) • s '" · y'" <:> y; (Q t [0.56 • (zln) • s "'n31'
n; Roughness Coefficient; 0 .018
S ; StreeVGutter Slope (fVft)
y ; Depth of flow at inlet (ft)
Capacity of Inlets on grade :
O c ; 0 .7 • [1 /(H1 -H2)] • [H1
512 -H,'12 ]
O c ; Flow capacity of inle t (cfs)
H ,; a+ y
H2 ; a ; gutler depression (2" Standard ; 4" Recessed)
y; Depth of flow in approach gutle r (ft)
a .,.,_.
(els)
0 .00
0 .00
100 year storm
a. ...... Q10-Tot• Y100 a,_,_ Oupac:lty Qltyp•• Ouptufed O c.,ryo ... •r Qbyp-totail OupMotl 0100-Totfll s LIC:tuai
(els) (els) (ft) I (In) (ft) (els) (els) (els) (els) I from l nl•ll (els) (els) (els) (ft/ft) (ft)
1.77 1.77 o .243 I 2 .92 0 .54 2.71 -0 .32 2 .39 I 0.00 2.39 2.39 0.01 00 5 ------4 .75 4 .75 o .352 I 4 .22 0 .64 6.45 -0 .05 6.40 I 0.00 6.40 6 .40 0.0 100 10
APPENDIXC
Storm Pipe & Channel Design Data & Calculations
14
South Hampton Subdivision -Phase 3
Pipe Calculations
Inlet Outlet 10 year storm 100 year storm
Pi pe# Size Length Slope
Invert Elev Invert Elev *Actual Flow Design Flow V10 Travel Time , tno *Actual Flow Design Flow V100 Travel Time , trioo
%Full %Full
(i n) (ft ) (%) (ft) (ft) (cfs) (cfs) (fps) (sec) (min) (cfs) (cfs) (fps) (sec) (min)
1 30 12.0 0.75 259.39 259 .30 -25.83 7.4 66 .6 2 0 .03 -34 .86 7.6 88 .4 2 0.0 3 --
2 27 36.6 1.20 260.08 259 .64 -24 .06 8 .7 65.4 4 0 .07 -32.47 9 .0 85 .0 4 0 .07
--
3 27 6.0 1.00 261.06 261 .00 -19.31 7 .8 60 .0 1 0 .01 -26.07 8.2 74.6 1 0.01
"These value s reflect the actu al flow fo r the 18" & 24" pipes . The design flow for these pipe sizes reflects a 25% reduction in pipe area .
South Hampton Subdivision
Phase 3 -Pipe Flow Diagram
0 10 (cfs)
Drainage Areas 1 +2 19 .31
J,
Pipe 3 19 .31
J,
Inlet 2 4 .75
J,
Pi pe 2 24.06
J,
Inlet 1 1.77
J,
Pipe 1 25 .83
J,
Drainage Area 6 3 .15
Into Proposed Drainage Channel II 28 .98 II
0 100 (cfs)
Drainage Areas 1+2 I 26 .07
J,
Pipe 3 26 .07
J,
Inlet 2 6.40
J,
Pipe 2 32.47
J,
Inl et 1 2 .39
J,
Pip e 1 34 .86
J,
Drainage Area 6 4 .25
Into Proposed Drainage Channel II 39 .11 II
Pipe 1 -10 Year Storm
Manning Pipe Calculator
Given Inp ut Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
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
3 0 .0000 i n
25.8300 cfs
0.0075 ft/ft
0.0140
19.9855 in
4.9087 ft2
3.4736 ft2
57 .2 883 in
94.2478 i n
7 .4362 fps
8.7312 in
66.6184 %
32 .9846 cfs
6.7196 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 P er imeter ............... .
Peri meter ...................... .
Velocity ....................... .
Hy draulic Radius ............... .
Percent Full ................... .
Full flow Fl o wra t e ............. .
Full fl o w v e loc ity ............. .
Sout h Ha mpto n Subdivision -Phase 3
College Station , Texas
Circular
Depth of Flow
30 .0000 in
34 .8600 cfs
0 .00 75 ft/ft
0 .0140
26.5221 in
4.9087 ft2
4.5915 ft2
73.4019 in
94.2 478 in
7 .5 923 fps
9.0076 i n
88 .4071 %
32.9846 cfs
6 .7 1 96 fps
Pipe 2 -10 Year S~orm
Manning Pipe Calculator
Giv en 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
27 .0000 in
24 .0600 cfs
0.01 2 0 ft/ft
0.0140
17 .6693 in
3 .9761 ft2
2.7572 ft2
50 .8888 in
84.8230 in
8 .7263 fps
7.8020 in
65 .4420 %
31.5030 cfs
7.9231 fps
Pipe 2 -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 ................... .
Ful l flow Flowrate ............. .
Full flow velocity ............. .
South Hampt o n Subdivision -Ph ase 3
College Stati o n, Texas
Circular
Depth of Flow
27.0000 in
32.4700 cfs
0.0120 ft/ft
0. 0140
22.9577 in
3.9761 ft2
3.6031 ft2
63.36 87 in
84 .8230 in
9. 0116 fps
8.1878 i n
85.0284 %
31.5030 cfs
7.9231 fps
-----·------------------------------
Pipe 3 -10 Year Storm
Mann i ng Pipe Cal cula tor
Given Input Data:
Sha pe .......................... .
Solving for .................... .
Diamet er ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results :
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Ve loc ity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Fl owra t e ............. .
Full flow v elocity ............. .
Circular
Depth of Fl ow
27 .000 0 in
1 9.3100 cfs
0 .0100 ft/ft
0. 0140
16.1940 in
3 .976 1 ft2
2 .4 898 ft2
47.8360 in
84 .8230 in
7.7 556 f ps
7 .4950 in
59 .9779 %
28.7 581 cfs
7.2328 fps
Pipe 3 -100 Year Storm
Manning Pipe Calcu lator
Given Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results :
Depth .......................... .
Area ........................... .
Wet t ed Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radi u s ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow ve l ocity ............. .
South Ha mp ton Subdivis i on
Col lege Sta ion, Texas
Ph ase 3
Circular
Depth of Flow
27 .000 0 in
26.0700 cfs
0 .0100 ft/ft
0 .0140
20.1482 in
3 .9761 ft2
3.1822 f t2
56.3142 in
84 .8230 in
8 .1925 fps
8.1371 in
74.6230 %
28.7581 cfs
7.2328 fps
Drainage Channel -10 Year Storm
Channe l Calcu l ator
Given Input Data:
Shape .......................... .
Solving for .................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Height ......................... .
Bottom width ................... .
Left slope ..................... .
Right slope .................... .
Computed Results :
Depth .......................... .
Velocity ....................... .
Full Flowrate .................. .
Flow area ...................... .
Flow perimeter ................. .
Hydraulic radius ............... .
Top width ...................... .
Are a ........................... .
Perimeter ...................... .
Percent full ................... .
Trapezoidal
Depth of Flow
28.9800 cfs
0.0063 ft/ft
0.0 2 50
30 .0000 in
0.0000 in
0.2500 ft/ft (V/H)
0 .2500 ft/ft (V/H)
16 .8884 i n
3.6578 fps
134. 1280 cfs
7 .9227 ft2
139 .2653 in
8.1921 in
135 .1072 in
25 .0000 ft2
247.3863 in
56.2946 %
Drainage Channel -100 Ye a r Storm
Channel Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Height ......................... .
Bottom width ................... .
Left slope ..................... .
Right slope .................... .
Computed Resu l ts :
Depth .......................... .
Ve loc ity ....................... .
Full F lowrate .................. .
Flow area ...................... .
Flow perimeter ................. .
Hydraulic radi u s ............... .
Top width ...................... .
Area ........................... .
Perimet er ...................... .
Percent full ............ .
So u t h Hampt o n S ubdi vls i o n -Ph ase 3
College Statio n, Texas
Trapezoidal
Depth of Flow
39.llOO cfs
0.0063 ft/ft
0 .0250
30.0000 in
0 .0000 in
0 .2500 ft/ft (V/H)
0.2500 ft/ft (V/H)
18 .897 7 in
3.9425 fp s
134. 1280 c f s
9.9201 ft2
1 55.8346 i n
9 .1667 i n
1 51 .1818 in
25.0000 ft2
247.3863 in
62.992 4 %
EXHIBIT A
Post-Development Drainage Area Map
2 1
Q'.3~ v
FOR OFFICE USE ONLY
P&Z CASE NO .: Q4 -} ~ S--
DATE SUBMITTED: 5-1./[J'--/
FINAL PLAT APPLICATION
(Check one) D Minor
($300.00)
D Amending
($300 .00)
D Final
($400 .00)
D Vacating
($400.00)
l:2f Replat
($600.00)*
*Includes public hearing fee
The following items must be submitted by an established filing deadline date for P&Z Commission consideration .
MINIMUM SUBMITTAL REQUIREMENTS:
_x__Filing Fee (see above) NOTE : Multiple Sheets -$55.00 per additional sheet
N/A Variance Request to Subdivision Regulations -$100 (if applicable)
_x__oevelopment Permit Application Fee of $200.00 (if applicable).
_x__lnfrastructure Inspection Fee of $600.00 (applicable if any public infrastructure is being constructed)
_LApplication completed in full.
!:!J.Pr_Copy of original deed restrictions/covenants for replats (if applicable).
_x__ Thirteen (13) folded copies of plat. (A signed mylar original must be submitted after staff review .)
_* _One (1) copy of the approved Preliminary Plat and/or one (1) Master Plan (if applicable).
_LPaid tax certificates from City of College Station , Brazos County and College Station l.S .D.
_LA copy of the attached checklist with all items checked off or a brief explanation as to why they are not.
_x_ Two (2) copies of public infrastructure plans associated with this plat (if applicable).
_::_Parkland Dedication requirement approved by the Parks & Recreation Board, please provide proof of
approval (if applicable).
* Pending ** Previously Approved
Date of Preapplication Conference: ___ O_c.._\-_c~~--<r __ b_1,........L_o_o_1 ___________ _
NAME OF SUBDIVISION South Hampton -Phase 3
SPECIFIED LOCATION OF PROPOSED SUBDIVISION (Lot & Block) Lots 1-3, Block 5; Lot 4. Block 3; Lots 1-4,
Block 6
APPLICANT/PROJECT MANAGER'S INFORMATION (Primary Contact for the Project):
Street Address 1101 University Drive East. Suite 108
State Texas Zip Code ~77~8~4~0 ___ _
Phone Number (979) 846-5735
PROPERTY OWNER'S INFORMATION:
City College Station
E-Mail Address phyllis@brazosla ndrealty.com
Fax Number (979) 846-0652
Name ~~~~~~~~~~N=an~t=uc~k=e~t=Lt=d~·~~~~~~~~~~~~~~~~~~~~
Street Address 1101 University Drive East, Suite 108
State Texas Zip Code ~77~8~4~0 ___ _
Phone Number (979) 846-5735
ARCHITECT OR ENGINEER'S INFORMATION :
City College Stat ion
E-Mail Address ph yll is @braz os lan d realty .com
Fa x Number (979) 846-0652
Name ~~~~~--'T~e=xc=o~n~-~J=o=e~S=c~hu=l=tz~P~·=E~-~~~~~~~~~~~~~~~~~~~~
Street Address 1707 Graham Road
State Texas Zip Code 77846
Phone Number (979) 764-7743
6/13 /03
C ity College Station
E-Mail Address joeschultz@texcon .net
Fax Number (979) 764 -7759
I o f I
Is there a temporary blanket easement on this property? If so, please provide the Volume N/ A; and Page# __ _
Acreage -Total Property l \ . 5 7 ] Total# Of Lots 11 R-0-W Acreage 0 · ~ ~
Exist ing Use : -"-V=a=ca=n"'""'"t __________ _ Proposed Use :_S~in ... g~le~-f~a~m=il.._y ~re~s~id~e~n~tia=I _______ _
Number Of Lots By Zoning District _ 11_ /POD P~aJe 1 ti.._ 3 I r>oc
Average Acreage Of Each Residential Lot By Zon ing District: f2-~ \ .,_.ic-
0\c.Jt 3 o. 3 7 I PDD -z_ .4 °1 I ~DO
Floodplain Acreage 0 .0 ~ \ ... T
A statement addressing any differences between the Final Plat and approved Master Plan and/or Preliminary Plat (if
appl icable):
N/A
Requested Varia nces To Subdivision Regulations & Reason For Same : ~N=o~ne-=----------------
Requested Oversize Participation : ~N=o~ne-=-----------------------------
Total Linear Footage of
Proposed Public:
f)Z-Streets
1.-7-0 Sidewalks
l~ l Sanitary Sewer Lines
5-z S' Water Lines
·z:z_ z_ Channels
5S Storm Sewers
0 Bike Lanes I Paths
Parkland Dedication due prior to filing the Final Plat:
ACREAGE :
___ # of acres to be dedicated + $ ____ development fee
___ # of acres in floodplain
# of acres in detention ---
___ # of acres in greenways
OR
FEE IN LIEU OF LAND :
11 #of Single-Family Dwelling Units X $556 = $ 6, 116 .00
N/A (date) Approved by Parks & Recreation Board
NOTE: DIGITAL COPY OF PLAT MUST BE SUBMITTED PRIOR TO FILING.
The applicant has prepared this application and certifies that the facts stated herein and exhibits attached hereto are true ,
correct, and complete. The undersigned hereby requests approval by the City of College Station of the above -identified
final plat and attests that this request does not amend any covenants or restrictions associated with this plat.
Date
6/13 /03 2 of 2
~ .•..
SUPPLEMENTAL DEVELOPMENT PERMIT INFORMATION
Application is hereby made for the following development SPEJ!<ific site/waterway alterations :
~ f='r"' S .f-r "'-c..-ht' ct. c_ o -n S .fr. .. J-, ~ .-.. -h .5 o -Ph. ~ ~ \I\
ACKNOWLEDGMENTS:
I, .J~~cf l 5 c1J+z.,. P'h'1 I/; f Hof,/,,,. , design engineer/owner, hereby acknowledge or affirm that:
The information and conclusions contained in the above plans and supporting documents comply with the current
requirements of the City of College Station , Texas City Code, Chapter 13 and its associated Drainage Policy and Design
Standards . As a condition of approval of this permit application, I agree to construct the improvements proposed in this
~~or~=nts and the requirements of Chapter 3 o! Col ege talion City Code.
~ e~tyvm~r(s)
CERTIFICATIONS: (for proposed alterations within designated flood hazard areas.)
A .I, certify that any nonresidential structure on or proposed to be on this site
as part of this application is designated to prevent damage to the structure or its contents as a result of flooding from the
100 year storm .
Engineer Date
B . I, certify that the finished floor elevation of the lowest floor, including any
basement, of any residential structure, proposed as part of this application is at or above the base flood elevation
established in the latest Federal Insurance Administration Flood Hazard Study and maps, as amended.
Engineer Date
-J~s~
Engineer Date
D. I, , do certify that the proposed alterations do not raise the level of the 100
year flood above elevation established in the latest Federal Insurance Administration Flood Hazard Study.
Engineer Date
Conditions or comments as part of approval : ___________________________ _
In accordance with Chapter 13 of the Code of Ordinances of the City of College Station , measures shall be taken to insure
that debris from construction, erosion , and sedimentation shall not be deposited in city streets , or existing drainage
facilities. All development shall be in accordance with the plans and specifications submitted to and approved by the City
Engineer for the above named project. All of the applicable codes and ordinances of the City of College Station shall
apply .
6 /13/03 3 of 3