HomeMy WebLinkAbout80 Development Permit 428 Pebble Creek Phase 2BMr. Ray Havens
Electric Transmission &
Distribution Superintendent
City of College Station
P.Q>. Box 9960
Gollege Station , Texas 77842
McCORD ENGINEERING, INC.
7607 Eastm ar k Dri ve, Su ite 102, P.O. Box 10047
College Stati o n , Texa s 77 842 (40 9) 764-8356
Fax (409)764-9644
January 3, 1994
RE: Pebble Creek Phase 2B Subdivision
R.evMe<l Electric Distribution/Service Cost Estimate
Dear Ray:
In accordance w i th the new policy of your C i ty, the Developer is responsible for
reimbursing your Cit y for 20 % of th e total estimated cost of electric service installati o n,
including labor , materials, and the standard fee percentages for engineering and overhead co st.
We compute that the 20 % cost contribution required for the Pebble Creek Phase 2B Subdivision
amounts to $ll,791.60. This cost was calculated based on a total electric service cost estim ate
of $63,957.00. The total electric service cost estimate developed for this project includes on
standard allowance of 30 % to co ver your City's labor related overhead costs, 7% for material
handling costs , and 8.5 % to co ver your City's administrative and engineering costs.
I trust you will find herewith all the information required. If not, or if questions arise ,
please do not hesitate to advise.
JDM /mw
Enclosures
cc: Mi. avld Pullen
Mr. Bob Pohl
Yours very truly,
McCORD ENGINEERING , INC.
'° . 6>. Srt c~Q
· m::r McCord , P.E.
President
Veronica Morgan, P.E.
Asst. to City Engineer
City of College Station
P .O . Box 9960
College Station, Texas 77842
Joe Orr, Inc.
Surveyors & Eng in eers
2167 Post Oak Circle
College Station , Texas 77845
(409) 690-3378
5 October 1993
Re: Pebble Creek 2B Street and Drainage Plans
Dear Veronica,
I am submitting the Drainage Report for Pebble Creek Phase 2B along with an application
for a Development Permit for this project. Construction Plans for the Streets and
Drainage have been submitted to the Development Coordinator.
Please review these documents and give your approval or comments at your earliest
convemence .
Thank you ,
~11&
President
Application Form
Development Permit
For Subdivisions Outside Flood Hazard Areas
City of College Station , Texas
(re : Ordinance No . 1728)
Site Description: Pebble Creek phase 2B
Located in : Lick Creek Watershed
Owner : Pebble Creek Development Co . Address : 4500 Pebble Creek Parkway
Telephone: 690-0990
Engineer : Joe Orr, Inc . -David Mayo Address: 2167 Post Oak Circle
Telephone : 690-3378
Contractor: Young Brothers Contractors, Inc . Address: P .O . Box 674 Bryan, TX
Telephone : 779-1112
Date Application Filed : 10/6/93 Approved:
Application is hereby made for the following development: Pebble Creek phase 2B
Drainage plans and supporting documents have been submitted.
ACKNOWLEDGMENTS :
I , David R. Mayo, as engineer, hereby acknowledge or affirm that :
The Drainage Plan and supporting documents submitted comply wit h the requirements of
Ordinance No. 1728
DaJid R. Mayo , P .E.
!<J/5/J J
Date / I
m; Joe Orr, Inc . g:
H\ Surveyors & Eng in eers rn
~j@ 2167 Post Oak Ci rcle ~l
[i::ii College Station, Texas 77845 ~]!:\'
(409) 690 -3378
Drainage Report
Pebble Creek Phase 28
Prepared by
David R. Mayo, P.E.
Joe Orr , Inc.
Su rveyors & Engineers
2167 Post O ak Circle
College Station , Texas 77845
(409) 690-3378
Drainage Report
Pebble Creek Phase 28
Prepared by
David R. Mayo, P .E.
for
Pebble Creek Development Company
4500 Pebble Creek Parkway
College Stat ion , Texas 77845
October 5, 1993
General Location and Description
Location: Pebble Creek phase 2B is located adjacent to Pebble Creek Parkway.
Augusta Circle is the only street proposed within this phase . This street begins at
Champions Boulevard in Pebble Creek phase 2C which has been platted to the northwest
of phase 2B. Champions Boulevard begins at Pebble Creek Parkway and is public only to
its intersection with Augusta Circle to the southeast and Stonebriar Circle to the
northwest. A location map is included on page 2 .
Description: This project consist of 46 .5 acres of upland covered with post oak, water
oak, elm, hickory and yaupon. About a third of the area is open and covered with bunch
grass such as native bluestem. The soil is of the Lufkin-Edge complex with some
Lakeland loamy fine sand . The slope is generally about 1 % with some steeper slopes to
the east where the tract slopes into the Lick Creek flood plain . There are no primary or
secondary drainageways traversing this tract. The development follows the Pebble Creek V
Master Development Plan and the Master Preliminary Plat of P eb ble Creek Phase 2 whicb
have been approved by the City of College Station .
Drainage Basins and Sub-Basins
Primary Drainage Basin: The Lick Creek drainage basin is the primary drainage basin (
into which drainage from this tract discharges . An analysis of this basin was conducted by
Walton and Associates/Consulting Engineers Inc . in 1986 for the City of College Station.
The report has been reviewed . A countywide Flood Insurance Study was prepared by the
Fort Worth District of the U.S. Army Corps of Engineers for FEMA. This work was
completed in September 1988 . FEMA has adopted the 100 year flood as determined by
this study as the base flood for floodplain management purposes. Map number
48041C0205 C dated July 2, 1992 from the Flood Insurance Rate Map for Brazos
County, Texas, has been included in the map pocket at the end of this report . Pebble
Creek phase 2B has been drawn on this map for location purposes . Approximately 1 acre
of the project falls within the floodplain show on this map , but elevations of all the
building sites are above those given for the flood plain in this area.
The portion of the Lick Creek floodplain adjoining this project has been developed into /
the Pebble Creek Golf Course . The area is constantly maintained.
Secondary Drainage Basin: Only a small offsite area from Pebble Creek phase 2C drains
through this project. This is from a grass covered area between Champions Boulevard
and this project. The drainage from this project into the Lick Creek basin is from five
separate drainage areas . These have been broken into sub-areas for the purpose of
determining street flow and inlet placement. A drainage map is included in the map
pocket at the end of this report which shows the drainage areas and routing through the
project.
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Pebble Creek Dev. Co.
50.0 Acne
Vol. 1 ~ Pg. 313
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Creek o....iopment Co. Pebble 11~2.60 Act'•
Vol . 1671, Pg. 276
City of College(~~
27.29 Acrnp 13
Vol. 1029, g.
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Pebble Creek Developmem-
11~60 Acree
Vol . 1671, Pg. 276
zoe Coal United J -.............,__:-\. r. l;: ~.Pg. ~0~ ', uv."' /'-.... .. 'v-\ ,...-, /
McCullough Realty Co.
~1.898 Acres
Vol . 365, Pg. 637
/
>f hillege Station City '5.oo Acres y-1422, Pg. 133
Drainage Design Criteria
Regulations: The City of College Station Drainage Policy and Design Standards have
been used as the primary design criteria for this project. Material referenced in the Design
Standards such at the "Hydraulic Manual" of the TSDHPT have also been used .
Development Criteria Reference and Constraints: This project site has had no
previous drainage studies made other than the general area studies for the primary
drainage basin . There will be little impact on adjoining tracts since the majority of the . /
outflow will be into the existing golf course drainag e system and not though areas of V
potential residential or business development.
Hydrological Criteria: The street in this project is a residential street and will be
designed to carry a 10 ear storm at cu dee or less with a 100 ear storm contained y1
within the right-of-way. The curb inlets and storm se w ers will e designed to carry no less
than a 10 year storm'."*
Rainfall intensities will be determined from the formul a
which was developed to plot rainfall intensity versus duration for each recurrence interval
as a straight line on log-log paper.
where :
I = rainfall intensity in inches per hour,
tc = the time of concentration of the watershed in minutes,
b = the y-intercept of the straight line,
d = a constant used to adjust the relationship to plot as a straight line , and
e = the slope of the straight line .
Values for b , d, and e have been determined for most locations , and a table from the
Bridge Division Hydraulic Manual of the TSDHPT which includes those for Brazos
County is included on the following page .
3
-N I Q) VI CD ;:o 0 G) m 0 < VI -NO z :z: --< °' 0 ;:o > c: r 0 3: > z c: > r COUNTY 2 year TABLE 6. CONSTANTS FOR USE IN FORMULA I = b/(tc+d)e Based on Weather Bureau (NWS) Technical Paper No. 40 "Rainfall Frequency Atlas of the United States" 5 year 10 year 25 year----m 50 year 100 year e b d e--~-d -e b d e b d e o · d e b d Anderson 0.799 62 8.6 0.792 77 8.8· 0.763 78 8.8 0.772 92 8.8 0.744 '93 8.8 --0~~99-8.6 Andrews 0.812 40 9.8 0.827 57 10~2 0.809 63 10.2 0.793 69 10.2 0.807 84 10.2 0.804 92 9.8 Angelina 0.785 62 8.8 0.762 69 7.6 0.746 73 7.6 0.726 77 7.6 0.727 86 7.6 0.716 90 8.8 Aransas 0.821 73 9.2 0.787 77 8.5 0.753 79 8.5 0.745 88 8.5 0.739 95 8.5 0.725 98 9.2 Archer 0.798 49 9.2 0.783 61 8.5 0.794 74 8.5 0.789 86 8.5 0.792 100 8.5 0.784 111 9.2 Armstrong 0.846 52 l0.8 0.819 63 10.4 0.820 75 10.4 0.835 95 10.4 0.831 105 10.4 0.840 113 10.8 Atascosa 0.808 60 9.2 0.791 74 9.0 0.780 80 9.0 0.770 90 9.0 0.757 95 9.0 0.761 108 9.2 Austin 0.811 69 8.0 0.781 75 8.1 0.757 79 8.1 0.739 85 8.1 0.733 92 8.1 0.719 95 8.0 Bailey 0.833 44 9.8 0.848 62 9.0 0.777 . 55 9.0 0.806 72 9.0 0.819 85 9.0 0.825 101 9.8 Bandera 0.795 52 8.6 0.770 62 8.2 0.774 72 8.2 0.764 82 8.2 0.765 94 8.2 0.769 105 8.6 Bastrop 0.802 62 8.2 0.781 72 8.4 0.765 77 8.4 0.762 88 8.4 0.748 93 8.4 0.747 103 8.2 Baylor 0.800 48 9.4 0.780· 59 8.8 0.797 75 8.8 0.791 87 8.8 0.801 103 8.8 0.790 112 9.4 Bee 0.815 65 9.8 0.796 78 8.7 0.762 79 8.7 0.760 92 8.7 0.748 97 8.7 0.740 103 9.8 Bell 0.798 56 8.0 0.780 69 8~5 0.773 77 8.5 0.771 90 8.5 0.754 93 8.5 0.751 102 8.0 Bexar 0.798 56 8.7 0.784 70 8.7 0.779 79 8.7 0.769 88 8.7 0.756 94 8.7 0.762 107 8.7 Blanco 0.792 53 8.3 0.777 65 8.4 0.776 75 8.4 0.766 85 8.4 0.758 93 8.4 0.758 104 8.3 Borden 0.810 43 9.4 0.808 58 10.2 0.802 66 10.2 0.805 80 10.2 0.795 87 10.2 0.794 96 9.4 Bosque 0.784 51 7.9 0.779 66 8.6 0.772 74 8.6 0.776 91 8.6 0.765 97 8.6 0.761 104 7.9 Bowie 0.768 50 7.7 0.769 64 8.0 0.753 68 8.0 0.743 76 8.0 0.742 83 8.0 0.740 92 7.7 Brazoria 0.796 69 7.8 0.751 70 8.0 0.749 80 8.0 0.730 85 8.0 0.718 90 8.0 0.696 89 7.8 Brazos O.B06 65 8.0 0.785 76 8.5 0.763 80 8.5 0.754 89 8.5 0.745 98 8.5 0.730 96 8.0 Brewster 0.860 50 10.4 0.819 60 9.6 0.833 70 9.6 0.818 78 9.6 0.833 91 9.6 0.832 110 10.4 Briscoe 0.835 50 10.5 0.824 63 10.3 0.815 73 10.3 0.823 89 10.3 0.818 101 10.3 0.832 115 10.5 Brooks 0.828 73 9.3 0.797 80 9.1 0.769 82 9.1 0.771 97 9.1 0.746 98 9.1 0.738 99 9.3 Brown 0.775 43 7.7 0.770 57 7.6 0.763 66 7.6 0.768 80 7.6 0.770 91 7.6 0.763 98 7.7 Burleson 0.805 64 8.0 0.784 74 8.4 0.763 79 8.4 0.760 90 8.4 0.743 97 8.4 0.739 98 8.0 Burnet 0.791 51 8.1 0.773 64 8.5 0.777 75 8.5 0.769 86 8.5 0.758 94 8.5 0.758 103 8.1 Caldwell 0.800 60 8.2 0.785 72 8.5 0.769 77 8.5· 0.764 88 8.5 · 0.748 92 8.5 0.749 104 8.2 Calhoun 0.810 70 8.9 0.772 73 8.4 0.760 81 8.4 0.745 88 8.4 0.737 95 8.4 0.720 96 8.9. Callahan 0.774 42 8.2 0.767 55 8.1 0.776 68 8.1 0.770 80 8.1 0.783 95 8.1 0.774 100 8.2 Cameron o.826 74 9.2 o.786 78 8.8 o.781 9o 8.8 o.760 95 8.8 o.727 93 8.8 o.730 102 9.2 Camp 0.779 53 8.0 0.782 70 8.8 0.761 74 8.8 0.758 84 .8.8 0.743 87 8.8 0.740 94 8.0 Carson 0.852 55 10.6 0.828 65 10.6 0.829 77 10.6 0.842 97 10.6 0.849 113 10.6 0.840 114 10.6 Cass o.769 50 7.7 o.768 65 8.3 o.750 69 8.3 o.746 78 8.3 o.738 83 8.3 0.737 91 7.7 Castro 0.842 49 10.4 0.819 56 9.5. 0.802 65 9.5 0.827 84 ~.5 0.829 95 9.5 0.823 105 10.4 ( ( (,.
The contributing drainage areas in this project are small. None are over 5 acres.
Therefore we will use the Rational Formula to determine runoff. T his formula ~
expressed as
Q=ciA .j
where:
Q =discharge in acre-inches per hour which is equivalent to cubic feet per second (cfs)
c is a runoff coefficient having no units,
i is the rainfall intensity in inches per hour, and
A = area in acres of land contributing to the runoff.
Since the drainage areas are small, we have elected to use a mm1mum time of
concentration instead of determining a flow path from the most hydraulically remote point
in each drainage area . A time of 15 minutes will be used which is generally considered the /
minimum for large residential lots. '"
The following is a tabulation of the rainfall intensity equation using constants for 10, 25
and 100 year storm events for Brazos County .
Rainfall Intensities
Brazos County, Texas
Constants for use in the formula l=b/(Tc+d)"e from SDHPT Manual
Storm e b d
2 0.806 65 8 .00
5 0.785 76 8.50
10 0.763 80 8 .50
25 0.754 89 8 .50
50 0.745 98 8.50
100 0 .730 96 8 .00
Tc(min) Storm Intensity
Frequency in/hr
15 10 7.19
15 25 8 .23
15 100 9.73
5
A weighted runoff coefficient has been calculated for this project using Table 5 on page 2-
15 of the TSDHPT Bridge Division Hydraulic Manual. A copy is included on the
following page.
The lots in this project are large single family residential. There are 58 lots in 46 .5 acres
which has an average lot size of 0 .8 acre or 34,900 square feet. The total right-of-way
area is 5 .68 acres of which 4 .83 acres is paved and the remainder is grass. This is 3,626
square feet of street pavement per lot. Assuming the average house has a 4 ,000 square
j foot ground area and there are 3,900 square feet of drive and walk per lot, there will be
])% im pervious and 67% g rass .a re ~ The runoff coefficient table shows a "c" of
approximately 0.85 for the impervious areas and 0 .15 for the grass areas . This yields a
weighted "c" of 0 .38. .J -
There is no detention proposed in this project , as previous studies have shown that the
Pebble Creek development will have a faster peak runoff than the runoff from the entire
Lick Creek watershed.
Hydraulic Criteria: The street capacities in this project will be determined by
considering each half of the street as a triangular channel with one vertical side. The
Manning Equation,
V= (1.486/n)R2/3s 112 ,
will be used to determine the velocities and capacities . The roughness coefficient "n" is
assumed to be 0 .015 for part concrete and part asphalt surface . The inlet equations from
the City of College Station Design Standards
Q=3 .0 L y312
will be used to determine the length of opening required for all inlets in a sump or on a
slope of 1 % or less with a 5" or greater depression at the entrance where
Q =total flow upstream of inlet , L= length of inlet throat (ft) and y= total depth of flow
at inlet, and
Q=O . 7L(l/y)((a+y)5/2_a512)
will be used to determine the length of opening required for inlets on grade with gutter
depression where
Q=total flow upstream of inlet , L= length (ft) of inlet throat required to capture Q, y=
depth of flow upstream of inlet and a= depression at inlet.
Capacities of Reinforced Concrete Storm Sewer will also be calculated using Manning's
Equation and an "n" value of 0.014 for concrete will be assumed .
6
TABLE 5. RUNOFF COEFFICIENTS FOR RATIONAL FORMULA
Type of Drainage Area
Business:
Downtown areas
Neighborhood areas
Resldentlal:
Slngle-famlly areas
Multl-unlts, detached
Multl-unlts, attached
Suburban
Apartment dwelllng areas
I ndustrlal:
Light areas
Heavy areas
Parks, cemeteries
Playgrounds
Rallroad yard areas
Unimproved areas
Sand or sandy loam sol I, 0-3%
Sand or sandy loam soll, 3-5%
Black or loesslal sol I, 0-3%
Black or loesslal soll, 3-5%
Black or loesslal soll, >5%
Deep sand area
Steep grassed slopes
Lawns:
Sandy
Sandy
Sandy
Heavy
Heavy
sol I,
sol I,
sol I,
sol I,
sol I,
flat 2%
average 2-7%
steep, 7%
flat 2%
average 2-7%
Heavy sol I, steep, 7%
Streets:
Aspha I tl c
Concrete
Brick
Drives and walks
Roofs
from ASCE, 1960
Runoff Coef f lclent
o. 70-0.95
0.50-0.70
0.30-0.50
0.40-0.60
0.60-0.75
0.25-0.40
o.50-0.10
0.50-0.80
0.60-0.90
0.10-0.25
0.20-0.40
0.20-0.40
0.10-0.30
0.15-0.20
0.20-0.25
0.18-0.25
0.25-0.30
0.10-0.60
0.05-0.15
0.70
0.05-0.10
0.10-0.15
0.15-0.20
0.13-0.17
0.18-0.22
0.25-0.35
0.70-0.95
0.80-0-95
o. 70-0.85
0.75-0.85
o. 75-0.95
BRIDGE DIVISION HYDRAULIC MANUAL
2 -1 5
12-85
•
Drainage Facility Design
General Concept: The initial phase of the drainage d esig n for this project was to analyze
the drainage patterns from the topo and determine curb inlet placement from street
capacities and lot layout. Inlets were then sized and storm sewer pipe sizes were
determined .
Specific Details: Each drainage area and storm drain w ill be outlined in this section.
Drainage Area "A" and Storm Drain No. 1
Augusta Circle begins at Champions Boulev ard and slopes southeast at a grade of 2.5%.
At station 5+02 .89, which is an intersection, the grade changes to 2 .0% and at station
9+00 the grade changes to 0 .5%. The follo w ing is a t abulation of the capacity of one-half
of this street at a 2 .00% grade .
Street Grade(%) ................................. .
Manning's Roughness Coefficient (n-
value) ........ .
Street Width (feet) .............................. .
Street Crown (in .) ............................... .
Street Side Slope (horizontalNertical) .......... .
Program Results :
2.00
0.0150
39
7
32.6
Depth Flow Rate Velocity Velocity Energy Flow Area Top Width
(ft.) (cfs) (fps) Head (ft) Head (ft) (sq ft)
0 .1 0 .3 1.86 0 .054 0 .154 0.2
0 .2 1.9 2 .96 0 .136 0 .336 0.7
0 .3 5 .7 3 .88 0 .233 0.533 1.5
0.4 12 .2 4.69 0 .342 0 .742 2.6
0.5 22 .2 5.45 0.461 0.961 4 .1
On the drainage map , w e have outlined Drainage Area "A" and divided it into two sub-
areas for collection onto each side of the street. We assum ed that an inlet would be
installed in the curve at about station 9+00 and a storm drain w ould be installed along the
lot line to the existing dry branch of Lick Creek in the undeveloped area at the rear of the
lots . Drainage Area "Al" collects onto the left side of the street and is the largest area
(3 .03 acres). Looking back at the rainfall intensit y calculations, we find that for a 15
minute time of concentration, we have 7 . 19 inches per hour for a 10 year storm and 9 . 73
iph for a 100 year storm . We have determ ined the weighted runoff coefficient to be 0 .38 .
8
(ft)
3.3
6 .5
9.8
13 .0
16.3
From this data, we calculate Q10=8 .3 cfs and Q100=11 .2 cfs . Looking abo v e to the street
capacity table , we see that these quantities can be contained with less than curb deep flow .
Drainage Area 11 A2 11 flows onto the right side of the street and is only 2 .04 acres with a
Q10of5.6 cfs and a Q100 of7.5 cfs , therefore this inlet placement will be satisfactory.
Next, we need to determine the length of the inlet throat. The street grade changes to
0 .5% just past the inlet and the inlet is depressed and recessed . We will check the length
for both an inlet in a sump and a depressed inlet on grade . The following tabulation shows
the results of these calculations .
. •.s.•.·.•.•.:.•.'.:.u.'·.':.··.·.'.'·.'.r.'.'.•.•.b..·.·.•.•.'.·.:.•.:.•.1 ...... n.'.':.•·.'.'.'.•.1.·.·.e..·.'.'.'.'.'.t.·.·.·.•.•.•.•·.a.· .. :.•.•.•.•.•.a.'.'.'.'.'.n .... •.·:··.·.a.'.'.'.'.'.'.a.·.'.•.'.'.·.1.·.·.~,' ... >*.'.•.: ... •. ::::: •:nrr(•> ::: : • •t• · · •• • : • )• J\? t • rn :~.1: :-:-:·:·:·:<·=·=·=·=·=·=·=·=·=·=·=·=·=·=-=·=·=-=·=···=-=·>:·:·=···:··-=·:·:·:·:·=-=···:-:-:-:-:-:-:::-:·:-===·=·=·=·=·=·===-=·=-=·==:====-:·====:====·:=:-:-:-:=·.·.·=·····. · ..
Flow (Q)
(cfs)
8 .3
11 .2
Depth
(feet)
0.5
0.5
Length Length
(in sump) (on grade)
2.2
2 .9
5 .3
7 .2
Depression
(ft)
0 .67
0 .67
A standard 5' single inlet would be satisfactory for an inlet in a sump , but we will use a
standard 10' double inlet to be sure to intercept all the street flow .
We now need to determine the size of pipe for the storm drain . The storm drain across
the street must be able to carry the Q 10 from Drainage Area 11 Al 11 . An 18 11 RCP at a
1. 00% slope was tried and found to carry the Q 1 o flow of 8 . 3 cfs at less than 7 5%
maximum capacity. This meets the requirements of the City of College Station Design
Standards. The Q100 flow is slightly greater than the maximum capacity of this pipe, but
can be contained within the right-of-way . A 24 11 RCP at a 1.25% slope was tried as the
outfall storm drain from the street to the creek at this point. This will carry the total Q 1 o
flow of 13 .9 cfs from Drainage Area 11 A 11 at 1.1 feet deep with a velocity of 7.8 fps . The
maximum capacity of this pipe is greater than the 18 .7 cfs Q100 flow at this point.
Results of these calculations are presented on the following two pa g es .
Drainage Area "B" and Storm Drain No. 2
At station 13+64 on Augusta Circle, a natural drain crosses the street right-of-way and
runs between Lots 25 and 26 in Block I 7 onto the golf course . We will install a storm
drain at this point.
Drainage Area 11 B 11 has been outlined on the Drainage Map and divided into three sub-
areas to determine flow onto each side of the street and into the curb inlets . Drainage
Area 11 B 111 is 2 .08 acres and collects onto the left side of the street between Storm Drain
No . 1 and Storm Drain No . 2 . Q10 flow from this area is 5 .7 cfs and Q100 flow is 7.7 cfs .
The street grade in this area is 0 .5%. Drainage Are a 11 B2 11 flows onto the right side of the
street in this area and has a Qio of 1.9 cfs and Q100of2 .6 cfs . A street flow tabulation
follows .
9
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 18 11 RCP @ 1.00% -Storm Drain No. 1
Solve For Actual Depth
Given Input Data:
Diameter ......... .
S 1 ope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94D ....... .
Froude Number .... .
1. 50 ft
0.0100 ft/ft
0.014
8.30 cfs
1. 06 ft
6.20 fps
1.34 sf
1.12 ft
0.0089 ft/ft
70.88 %
9.75 cfs
10.49 cfs
1.10 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
10
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 24 11 RCP @ 1.25% -Storm Drain No. 1
Solve For Actual Depth
Given Input Data:
Diameter ......... .
slope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94D ....... .
Froude Number .... .
2.00 ft
0.0125 ft/ft
0.014
13.90 cfs
1. 11 ft
7.79 fps
1. 78 sf
1. 34 ft
0.0070 ft/ft
55.36 %
23.49 cfs
25.26 cfs
1.45 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
11
I Street Grade(%) ................................. .
Manning's Roughness Coefficient (n-
value ) ........ .
Street Width (feet) .............................. .
Street Crown (in.) ............................... .
Street Side Slope (horizontalNertical) .......... .
Program Results:
0.50
0 .0150
39
7
32.6
Depth Flow Rate Velocity Velocity Energy Flow Area Top Width
(ft.) (cfs) (fps) Head (ft) Head (ft) (sq ft)
0 .1 0 .2 0.93 0 .013 0 .113 0.2
0.2 1.0 1.48 0 .034 0 .234 0 .7
0 .3 2 .8 1.94 0 .058 0 .358 1.5
0.4 6 .1 2 .35 0 .086 0.486 2.6
0 .5 11 .1 2.72 0 .115 0 .615 4.1
The stormwater flow in this street section is well within the requirements of the City of
College Station Design Standards .
The inlet at the left side of Augusta Circle at Station 13+68 must be able to take the flow
from both Drainage Areas "Bl" and "B3 ". The Q 10 total from these areas is 10 . 7 cfs and
the Q100 total is 14.4 cfs . This inlet is depressed and on grade. The equation for this
type inlet yields the following:
Flow (Q) Depth Length Length Depression
(cfs) (feet) (in sump) (on grade) (ft)
1.9 0 .5 0 .5 1.2 0 .67
2 .6 0 .5 0 .7 1.7 0.67
10.7 0 .5 2.8 6 .9 0.67
14.4 0.5 3.8 9.2 0.67
We will use a standard 10' double inlet on the left side and a standard 5' single inlet on the
right side of the street at this point.
12
(ft)
3.3
6 .5
9.8
13.0
16.3
I
The storm drain at this point must be sized to carry the combined flow from Drainage
Areas 11 B l 11 and 11 B3 11 across the street and the total from all of Drainage Area 11 B 11 in the
outfall from the right side of the street. The Q 1 o left is 10 . 7 cfs and the Q 100 is 14 .4 cfs.
The total Qio from Drainage Area 11 B 11 is 12 .6 cfs and the Q100 is 17 .0 cfs .
A 24 11 RCP at a 1.20% slope is proposed at this location for the entire length of the storm
drain . This will carry the 17.0 cfs Qioo total flow at a depth of 1.28 feet and a velocity of
8.01 fps . Discharge will be onto the golf course with sheet flow to the existing creek.
Results of the pipe flow calculations follow on the next page.
Drainage Area "C" and Storm Drain No. 3
The placement of storm drain no . 3 is controlled by the outlet conditions . In order to meet
an inlet into the golf course drainage system , we will place the storm drain in an easement
between Lots 18 and 19 in Block 17 . Runoff from Drainage Area 11 C" will be collected in
curb inlets street station 21 +91.
The area which drains onto the left side of Augusta Circle between Storm Drain No. 2 and
street station 21+91 is 6 .13 acres . This produces a Qlo of 16 .7 cfs . The slope of the
street in this area is 0.5% for approximately 600 feet and increases to 1.00 % for the last
175 feet. From preceding calculations, we can see that 16 . 7 cfs is more than this street
can carry at 0 . 5%. Therefore, we must collect some of the stormwater from the left side
upstream of station 21 +91 . The collection point has been determined to be at street
station 17+08 .94. The area designated at Drainage Area "Cl" which is 2.64 acres collects
at this point. The Q10 from this area is 7 .2 cfs and Qioo is 9 .8 cfs . Q100 from this area
can flow through this section less than curb deep .
13
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 24 11 RCP @ 1.20% -Storm Drain No. 2
Solve For Actual Depth
Given Input Data:
Diameter ......... .
Slope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94D ....... .
Froude Number .... .
2.00 ft
0.0120 ft/ft
0.014
17.00 cfs
1. 28 ft
8.01 fps
2.12 sf
1. 49 ft
0.0080 ft/ft
63.94 %
23.01 cfs
24.75 cfs
1.34 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
14
Street Grade(%) ................................. .
Manning's Roughness Coefficient (n-
value) ........ .
Street Width (feet) .............................. .
Street Crown (in.) ............................... .
Street Side Slope (horizontalNertical) .......... .
Program Results :
0.50
0 .0150
39
7
32 .6
Depth Flow Rate Velocity Velocity Energy Flow Area Top Width
(ft.) (cfs) (fps) Head (ft)
0.1 0.2 0.93 0 .013
0.2 1.0 1.48 0 .034
0.3 2 .8 1.94 0 .058
0.4 6.1 2 .35 0 .086
0.5 11.1 2 .72 0 .115
The inlet at this point will be on grade and depressed 8 11
•
Flow (Q)
(cfs)
7.2
9 .8
Depth
(feet)
0 .5
0 .5
Length Length
(in sump) (on grade)
1.9
2 .6
4 .6
6.3
Head (ft)
0.113
0 .234
0 .358
0.486
0 .615
Depression
(ft)
0.67
0 .67
(sq ft)
0 .2
0 .7
1.5
2 .6
4 .1
A standard single inlet is only marginal wit h the Q10 flo w, therefore we will use a
standard 10' double inlet which will take the Qioo flow .
An 18 11 RCP at 1. 00% slope will be used from the outlet of th is inlet. This will carry the
Q10 flow at 64% full at a velocity of 6.04 fps and the QloO flow at below maximum
capacity . Calculation results are shown on the following page .
At street station 21 +91, the runoff from Draina ge Area 11 C2 11 will have collected in the
gutter. The Qio from this area is 9.5 cfs and the Qioo is 12 .9 cfs . The street grade is
1.00%.
15
(ft)
3 .3
6.5
9 .8
13.0
16.3
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 18 11 RCP @ 1.00% -Storm Drain No. 3
Solve For Actual Depth
Given Input Data:
Diameter ......... .
slope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 940 ••••••••
Froude Number .....
1. 50 ft
0.0100 ft/ft
0.014
7.20 cfs
0.96 ft
6.04 fps
1.19 sf
1. 04 ft
0.0080 ft/ft
63.91 %
9.75 cfs
10.49 cfs
1.17 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
16
Street Grade (% ) ................................. .
Manning's Roughness Coefficient (n -
value) ........ .
Street Width (feet) .............................. .
Street Crown (in .) ............................... .
Street Side Slope (horizontalNertical) .......... .
Program Results :
Depth Flow Rate Velocity Velocity Energy
(ft.) (cfs) (fps) Head (ft) Head (ft)
0.1 0.2 1.32 0.027 0 .127
0 .2 1.4 2 .09 0 .068 0 .268
0 .3 4.0 2 .74 0 .117 0.417
0.4 8 .6 3 .32 0 .171 0 .571
0.5 15.7 3 .85 0 .230 0 .730
The Q 100 flo w will not be curb de e p .
The inlet on the left side at this st ation w ill be on grade and dep resse d 8 ".
'_,-~_,'.'.·_:_.:::_.·_.',.•,t:t'.'.'_':'.'.'.·r·.=.'.'_,··.·,w_ .. '_=:'_'.',',•.,.=_,·•_,··1'.·.·n'_'.'.'.,':.'.'.':·.1'_ .. '_',·e'_'.':'.'.'.'.,t .. '_·.= .. =.,•_,.'_,·'.~.·.·'_•:'_.·.·.'_.·_.',.-a·.=.=.'_'.'.'.'9''':':.'.'.'.·.'_·a'.'_'.'.'.'.·~.=.'.':.'.'.'.,1' ... '_t·_,'_ .. ':':y;',::::,'_,',·.':·.',·.',···:··'.,·•_,·'.•,•_,· .:.::_:,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ,,,,,,,,,,,,,,,,,,,,, ::::::::::::::::::: .......... ::::::.. .. ::::'::::::::.:.:.: ....... ·.·.·.· ..... ,., .. ., ... ,., ... ,.,.,.,., =::::::::::::.,.,:::: :Wu U W. '°": ···················· · ·-:-:-:-:-:-:-:·:·:-:-:·:-:.:.:.:.:·:·:.:.:.:.:·:·:.:-:-:·:-:-:-:·:.:·:.:·:·:·:-:.:.:-:-:-:-:.:-:.:-:-:-:-:-:-:-:·:-:-:-:·:·:-:.:·:.:-:-:-:-:-:-:-:.;-·.· .... -·.· :::::::::::::::::::::::::::::::-:-:.;.·.·.·.····
Flow (Q)
(cfs)
9.5
12.9
Depth
(feet)
0 .5
0 .5
Length Length
(in sump) (on grade)
2 .5
3.4
6 .1
8 .3
Depression
(ft )
0 .6 7
0 .67
A standard 10 ' double inlet w ill be used w hic h w ill t ake the Q 100 flo w .
17
1.00
0 .0150
39
7
32 .6
Flow Area
(sq ft)
0 .2
0.7
1.5
2 .6
4 .1
Top Width
(ft)
3.3
6.5
9 .8
13.0
16.3
On the right side of the street at this point , Drainage Area 11 C3 11 must be collected in an
inlet on grade. Q10 is 3 .8 cfs and Q10 is 5 .1 cfs .
Flow (Q)
(cfs)
3 .8
5 .1
Depth
(feet)
0.5
0.5
Length Length
(in sump) (on grade)
1.0
1.3
2.4
3.3
A standard 5' single inlet will be used at this point.
Depression
(ft)
0 .67
0 .67
The storm drain from the left side inlet at street station 21+9 l to the outfall will be a 24 11
RCP at 1.38%. The Q10 from the total Drainage Area 11 C 11 is 20 .5 cfs and Q100 is 27 .8
cfs . Q10 will flow 1.39 feet deep at a velocit y of 8 .78 fps and Q100 is only slightly larger
than the maximum capacity of this pipe . The 1.2 cfs excess of Q100 can overflow in the
easement between Lots 18 and 19 . Calculation results are shown on page 19 .
The outlet from this storm drain will be into an inlet of the golf course storm drain system .
Drainage Area "D" and Storm Drain No. 4
Drainage Area 11 D 11 is the area that drains onto Augusta Circle between station 21 +91 and
station 33+50 . The area is 5 .59 acres and collects in a sump at station 26+ 16 . The total
Q10 from this area is 15 .3 cfs and Q100 is 20.6 cfs . The street slope is -2 .66% entering
and 2 .18% leaving the collection point.
Street Grade(%) ................................. .
Manning's Roughness Coefficient (n-
value) ........ .
Street Width (feet) .............................. .
Street Crown (in.) ............................... .
Street Side Slope (horizontalNertical) .......... .
Program Results:
2.18
0 .0150
39
7
32.6
Depth Flow Rate Velocity Velocity Energy Flow Area Top Width
(ft.) (cfs) (fps) Head (ft) Head (ft) (sq ft) (ft)
0 .3 5.9 4.05 0 .254 0.554 1.5 9.8
0.4 12 .8 4 .90 0 .373 0.773 2.6 13.0
0.5 23 .2 5.69 0.502 1.002 4.1 16.3
18
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 24" RCP@ 1.38% -Storm Drain No. 3
Solve For Actual Depth
Given Input Data:
Diameter ......... .
s 1 ope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94 D ....... .
Froude Number .... .
2.00 ft
0.0138 ft/ft
0.014
20.50 cfs
1. 39 ft
8.78 fps
2.33 sf
1. 62 ft
0.0097 ft/ft
69.58 %
24.68 cfs
26.55 cfs
1.37 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
19
QloO flow will be less than curb deep .
The inlet on the left side at station 26+ 16 must take the flow from Drainage Area "D l ".
The Qlo is 10.8 cfs and Q100 is 14 .6 cfs .
Flow (Q) Depth Length Length Depression
(cfs) (feet) (in sump) (on grade) (ft)
10.8 0 .5 2 .8 6 .9 0 .67
14.6 0 .5 3 .8 9.4 0 .67
A standard 5' single inlet will be used on each side .
A 24" RCP storm drain at 0 .80% slope will be used across the street at this point. This
will carry the Q100 flow of 14 .6 cfs from Drainage Area "Cl" at 1.33 feet deep and 6 .61
fps .
A 24" RCP storm drain at 2 .70% will be used at the outfall from the right side inlet to a
pond on the golf course. The total Q100 of 20 .6 cfs from Drainage Area "D" will flow
1.11 feet deep at 11. 5 cfs .
A summary of these calculations are on the following tw o pages .
20
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 24 11 RCP @ 0.80% -Storm Drain No. 4
Solve For Actual Depth
Given Input Data:
Diameter ......... .
Slope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94D ....... .
Froude Number .... .
2.00 ft
0.0080 ft/ft
0.014
14.60 cfs
1. 33 ft
6.61 fps
2.21 sf
1. 38 ft
0.0072 ft/ft
66.25 %
18.79 cfs
20.21 cfs
1.08 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
21
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 24 11 RCP@ 2.70% -Storm Drain No. 4
Solve For Actual Depth
Given Input Data:
Diameter ......... .
Slope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94D ....... .
Froude Number .... .
2.00 ft
0.0270 ft/ft
0.014
20.60 cfs
1.11 ft
11.47 fps
1. 80 sf
1. 63 ft
0.0097 ft/ft
55.64 %
34.52 cfs
37.13 cfs
2 .13 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
22
Drainage Area "E" and Storm Drain No. 5
Drainage Area "E" is 5 .93 acres draining onto Augusta Circle between stations 33+50 and
37+35. This has been divided into four sub-areas for street flow calculations . Drainage
Areas "EI" and "E4" drain onto the right side of the street and Drainage Areas "E2" and
"E3" drain onto the left side . The street slopes at a -1.20% from station 33+50 to station
34+79 and +3 .80 % from station 34+79 to 37+35 . Inlets will be installed on each side of
the street at station 34+79 and a storm drain will be installed from these inlets to the
existing storm drain on the golf course at the northwest side of this project.
Drainage Area "E4" is 0 . 3 0 acres and has a Q 1 o of 0 . 8 cfs and a Q 100 of 1. 1 cfs .
Drainage Area "E3" is 0.49 acres and has a Q10 of 1.3 cfs and a Q100 of 1.8 cfs . Area
"E4 " collects onto Augusta Circle on the right side between station 33+50 and 34+79.
Area "E3" drains onto the left gutter in this same area.
Street Grade(%) ................................ ..
Manning's Roughness Coefficient (n -
value ) .........
Street Width (feet) .............................. .
Street Crown (in .) ............................... .
Street Side Slope (horizontalNertical) .......... .
Program Results :
1.20
0 .0150
39
7
32 .6
Depth Flow Rate Velocity Velocity Energy Flow Area Top Width
(ft.) (cfs) (fps) Head (ft) Head (ft) (sq ft)
0.1 0 .2 1.44 0 .032 0 .132 0 .2
0.2 1.5 2 .29 0 .081 0 .2 81 0 .7
0 .3 4.4 3 .00 0 .140 0.440 1.5
0.4 9 .5 3.64 0 .205 0 .605 2 .6
0 .5 17 .2 4 .22 0 .276 0.776 4.1
The street flow from Areas "E3" and "E4" wi ll be well below curb deep .
Drainage Area "El" collects in the right gutter of Augusta Circle between station 34+79
and station 3 7+ 3 5, while the runoff from area "E2" collects in the left gutter in this same
area . The Q 100 is 13 . 3 cfs from "E 1 " and 6. 7 cfs from "E2".
23
(ft)
3 .3
6 .5
9 .8
13.0
16.3
Street Grade (% ) ................................. .
Manning's Roughness Coefficient (n-
value) ........ .
Street Width (feet) .............................. .
Street Crown (in.) ............................... .
Street Side Slope (horizontalNertical) .......... .
Program Results :
3 .80
0 .0150
39
7
32 .6
Depth Flow Rate Velocity Velocity Energy Flow Area Top Width
(ft.) (cfs) (fps) Head (ft) Head (ft) (sq ft)
0.3 7 .8 5 .34 0.443 0 .743 1.5
0.4 16.9 6.47 0 .650 1.050 2 .6
0 .5 30.6 7.51 0 .875 1.375 4 .1
The runoff from these areas will not exceed c urb deep flow .
The curb inlet on the left side at station 34+79 will receive a Q10 flow of 5 .5 cfs and a
Q100of8 .5 cfs . This inlet will be in a sump .
•,,c .. =,·.=.:.• .. :·'.•.u,.=.·.·.•.==.·.=.·.r.'.=.,•,,i;;;;.'.·.·.== .. •.·.=•,•.J,,..1.·.=.""=.'.=.•,,=.=·.=.· .. ·J=.·.·,e·.=.=.=.=.•,=t,'.·.=.•.J,,. ... ,=~ .. =,·.• .. • .. • .. :·'.• .. ·a',.=.·.=.·.=.·.h .. '.'.•.•,·a·.·.=.=.=.·.•.k..,•.=.= .. •.·.·,·1·.=.·.=,!.=.·.··.•:·.·.··,•.=•,.=.••,··.••,,..!.,..= = .. • : Tr = :: • ::: • • :•• .. : ::: : : ::: : • • , =· < = •• • • u. 1::1 u ~ u. ~ ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::·:::::::::::::::::·:::::·:::::::·:::::::::::::::::::::;:;:·:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::-:::::·:··-::·.·.
Flow (Q)
(cfs)
5 .5
8 .5
Depth
(feet)
0 .5
0 .5
Length Length
(in sump) (on grade)
1.4
2 .2
3.5
5 .5
Depression
(ft)
0 .67
0 .67
A standard 5' single inlet will be satisfacto ry on th e left side at thi s point.
The right side inlet at this station w ill re ceive a Q lo of l 0 . 6 cfs and a Q 100 of 14 . 4 cfs .
Flow (Q)
(cfs)
10.6
14.4
Depth
(feet)
0 .5
0.5
Length Length
(in sump) (on grade)
2 .8
3 .8
6.8
9 .2
Depression
(ft)
0 .67
0 .67
The inlet is in a sump , therefore a standard 5' sin g le inl et will b e satisfactory .
24
(ft)
9 .8
13.0
16.3
A storm drain will be installed across Augusta Circle at station 34+ 79 and though a
drainage easement between Jots 7 and 8 to the existing 30" RCP storm drain on the golf
course at the rear of these lots . The drain across the street will receive a combined Qio of
5.5 cfs and a combined Qioo of 8.5 cfs . An 18" RCP at 2 .0% slope will be used. Q10
flow will be 0.66 feet deep at 7 .37 fps . This is 44% full. The maximum capacity of this
drain is 14.84 cfs which is greater than the Qioo flow. Results of these calculations are
presented on the following page.
A 24" RCP storm drain at 2.0% slope will be installed from the outlet of the right curb
inlet to the existing golf course storm drain. Total Qlo from Drainage Area "E" is 16.1
cfs and Qioo is 22 .9 cfs . The Q10 flow will be l.05 feet deep at a velocity of 9.65 fps and
the maximum capacity is 32 cfs . Calculation results are on page 27 of this report .
The existing golf course storm drain which will recei v e this runoff is a 30" RCP at a slope
of approximately 6%. The maximum capacity of this drain is approximately 100 cfs . The
Qioo flow from Drainage Area "E" is only 34% of the maximum capacity . The design
flow from the offsite drainage which enters this storm drain upstream of this point is to be
carried in a 24" RCP at a flatter slope . There should be excess capacity in this pipe .
Other Drainage Areas
Except for a small area which drains onto Pebble Creek Parkway, all the drainage from
this project which does not drain onto Augusta Circle, drains onto the golf course and will
be handled by the golf course drainage system . The portion which drains onto Pebble
Creek Parkway has been addressed in the Pebble Creek phase 1 F and 1 G drainage report.
25
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 18 11 RCP @ 2.00% -Storm Drain No. 5
Solve For Actual Depth
Given Input Data:
Diameter ......... .
s 1 ope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94D ....... .
Froude Number .... .
1. 50 ft
0.0200 ft/ft
0.014
5.50 cfs
0.66 ft
7.37 fps
0.75 sf
0.90 ft
0.0069 ft/ft
43.90 %
13.79 cfs
14.84 cfs
1.83 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
26
Circular Channel Analysis & Design
Solved with Manning's Equation
Open Channel -Uniform flow
Worksheet Name: Pebble Creek 2B
Comment: 24" RCP @ 2.00% -Storm Drain No. 5
Solve For Actual Depth
Given Input Data:
Diameter ......... .
s 1 ope ............ .
Manning's n ...... .
Discharge ........ .
Computed Results:
Depth ............ .
Velocity ......... .
Flow Area ........ .
Critical Depth ... .
Critical Slope ... .
Percent Full ..... .
Full Capacity .... .
QMAX @. 94D ....... .
Froude Number .... .
2.00 ft
0.0200 ft/ft
0.014
16.10 cfs
1. 05 ft
9.65 fps
1. 67 sf
1. 45 ft
0.0077 ft/ft
52.46 %
29.71 cfs
31.96 cfs
1.86 (flow is Supercritical)
Open Channel Flow Module, Version 3.12 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
27
Conclusions
The design of these drainage facilities is in compliance with the City of College Station
Drainage Policy and Design Standards. The design provides for adequate control of the
stormwater flow through this project from both the 10 year design storm and the 100 year
flood . The design is for ultimate development. Off site routing is through the golf course
to Lick Creek and since this area is under constant maintenance, there should be no storm
damage problems .
I hereby certify that this report for the drainage design of Pebble Creek phase 2B was
prepared by me in accordance with the provisions of the City of College Station Drainage
Policy and Design Standards for the owners thereof.
28
Pebble Creek Phase 2B
College Station, Texas
Streets and Drainage
3 Oct 93
Item Description
No.
1. Clearing and Grubbing
Jo e Orr, In c.
Surveyors & Engineers
2 167 Po st Oa k Ci rcle
Coll ege Sta tion , Texas 7784 5
(409 ) 690 -3378
Engineer's Est imate
Unit Quantity
Acre 5.7
2. Common Roadway Excavation C.Y. 12500
3. 6" Lime Stabilized Subgrade S.Y. 18841
4. Curb and Gutter L.F. 7971
5. 7" Crushed Limestone Base S .Y. 16041
6 . 1 1/2" HMAC Type "D" S.Y. 16041
7 . 24" RCP Storm Drain L.F . 1668
8. 18" RCP Storm Drain L.F. 555
9. Standard 5' Single Inlet Ea . 5
10 . Standard 1 O' Double Inlet Ea . 6
11 . 6' Concrete Sidewalk S.F. 49150
12 . Reinforced Concrete Intersection S.F . 756
13 . Monolithic Curb L.F . 79
14. Seeding S.Y. 4107
15. Block Sod S.Y. 100
Prepared by :
Oa~
Unit Amount
Price
$4,500 .00 $25,650.00
2.50 $31 ,250.00
2 .30 $43,334.30
6.50 $51,811.50
6 .15 $98,652.15
3 .20 $51,331 .20
25 .00 $41,700 .00
20 .00 $11,100 .00
1,750 .00 $8,750 .00
2,500 .00 $15,000.00
1.00 $49,150.00
3 .00 $2,268 .00
3 .00 $237.00
.10 $410 .70
3.00 $300.00
$430,944 .85
Item No.
Water
Pebble Creek phase 28
College Station, Texas
20-Sep-93
Description Unit
1. 8" PVC AWWA C900 DR14 PVC Waterline L.F .
3. 8" X 8" Tee Ea .
4. 8" X 6" Tee Ea .
5. 8" Gate Valve w/box Ea .
6. Fire Hydrant Installation Ea .
7 . 1-1/2" Service Tap on 8" PVC Ea .
8. 1" Service Tap on 8" PVC Ea.
9. 1-1/2" Type "K" Copper Service Line L.F.
10 . 1" Type "K" Copper Service Line L.F .
Total for Water
Quantity Unit Price Amount
4305 12.50 53 ,812 .50
1 250 .00 250.00
6 200 .00 1,200.00
8 500.00 4,000 .00
6 1,500.00 9,000 .00
11 295 .00 3,245.00
1 175.00 175 .00
583 8.25 4,809 .75
99 7.50 742.50
$77,234 .75
Prepared by :
Item No .
Water
Pebble Creek phase 28
College Station , Texas
6-Sep-93
1. 8" PVC AWWA C900 DR14 PVC Waterline L.F .
3. 8" X 8" Tee Ea .
4. 8" X 6" Tee Ea .
5. 8" Gate Valve w/box Ea .
6 . Fire Hydrant Installat ion Ea .
7. 1-1/2" Service Tap on 8" PVC Ea .
8. 1" Service Tap on 8" PVC Ea .
9. 1-1/2" Type "K" Copper Service Line L.F .
10. 1" Type "K" Copper Service Line L.F .
Total for Water
C8
--: f? ~
Quantity Unit Price
4305 12 .50
1 250 .00
6 200 .00
8 500.00
6 1,500.00
11 295.00
1 175 .00
583 8.25
99 7.50
Prepared by:
Amount
53 ,812 .50
250 .00
1,200.00
4 ,000 .00
9,000.00
3,245 .00
175 .00
4 ,809 .75
742 .50
$77 ,234.75
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