HomeMy WebLinkAbout8 Development Permit 366 First National Bank L O Ball Memorial Subd.John Hall, Chairman
Pam Reed, Commissioner
Peggy Gamer , Commissioner
TEXAS NATURAL RESOURCE CONSERVATION COMMISSION
Protecting Texas by Reducing and Preventing Pollution
Alan Gibbs
Municipal Development Group
P.O. Box 9249
October 28, 1994
College Station, Texas 77840-9249
Re: &i y of College Stat t on
.0. Ball Memorial Subdivision
:i:NR Gt-~ermit-No: 10024-001
WWPR Log No: 104/157
County: Brazos
Dear Mr. Gibbs:
We have received the design submittal included with your cover letter dated
October 13, 1994.
The rules which regulate the design, installation and testing of domestic
wastewater projects are found in 30 TAC, Chapter 317 , of the TNRCC's rules
titled, "Design Criteria for Sewerage Systems". All plans and specifications
submitted for TNRCC approval must comply with these rules.
Beginning on September 1, 1994, severe budget reductions required the TNRCC to
eliminate most reviews of domestic wastewater project plans and specifications.
At most, only a cursory review of the proposed project was performed. A
technical review to determine conformity with 30 TAC Chapter 317 has NOT been
performed . The proposed project is approved with the following comments and
c ondit i ens:
1. An engineering report must be prepared and sealed by a Professional
Engineer registered in the State of Texas. This engineering report
must include all constants, graphs, equations , and calculations, which
are needed to both justify the design and show full compliance with
Section 317.1 (c) of the TNRCC's rules requiring a final engineering
report. Copies of this report shall be made available to the TNRCC,
upon request.
2. The final version of the project plans and specifications shall include ·
any and all information necessary to show full compliance with the
applicable requirements detailed in Chapter 317 of the TNRCC 's rules.
Copies of the final version of the project plans and specifications
shall be made avialable to the TNRCC, upon request.
RE CEIVED DEC 0 1 199\
P.O. Box 13 08 7 • Au sti n, Texa s 78711 -308 7 . • 51 2/23 9-1000
Alan Gibbs
Page 2
3. Any test results necessary to show comp l iance with the testing require-
ments of Chapter 317 shall be made avai l able to the TNRCC, upon request.
4. The TNRCC still maintains its review authority and may utilize this
authority at any time in the future. If plans are to undergo review,
TNRCC will notify you upon receipt of the project. Also, please be aware
of Section 317.l(a)(2)(A) of the rules which states, "Approval given by the
Commission is not intended to relieve the sewerage system owner or the
design engineer of any liabilities or responsibilities with respect to
the design, construction, or operation of the project."
5. Within 60 days of the completion of construction, an appointed engineer
must notify both the Permitting Section of the TNRCC's Watershed Management
Division and the appropriate Region Office of the date of completion.
The engineer must also provide written certification that all construction,
materials and equipment, and test results were substantially in accordance
with the approved plans and specifications, the rules of the TNRCC and any
change orders filed with the TNRCC. All notifications, certifications and
change orders must include the signed and dated seal of a Professional
Engineer registered in the State of Texas.
6. All plans and specifications shall conform wit h any other waste discharge
requirements and water quality standards established by the TNRCC, as the
requirements pertain to a regulated discharge.
If you have any questions or if we can be of any further service, please
call me at (512) 239-4554.
Since r ely,
~w.w~
Thomas W. Weber
Manager, Permitting Section
Watershed Management Division
cc: City of College Sta t ion
TNRCC, Region 9 Office
I
FINAL DRAINAGE REPORT
FOR THE
L.O. BALL MEMORIAL SUBDIVISION
PHASE II
LONGMIRE DRIVE
COLLEGE STATION, BRAZOS COUNTY, TEXAS
FEBRUARY, 1999
MAR 1 2 1999
COLLEGE STATION
EN I 11NG
MUNICIPAL DEVELOPMENT GROUP I ~'JI •IS 2551 TEXAS AVENUE . SOUTH , STE . A
COLLEGE STATION, TEXAS 77840
Ph : (409)693-5359 Fx : (409) 693 -4243 ~Consulting Engineers · Environmental· Surueyors·Planners
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TABLE OF CONTENTS
1.0 PROJECT SCOPE ................................................................................................. 4
I .I SITELOCATION .................................................................................................... 4
1.2 GENERAL DESCRIPTION ..................................................................................... 4
2.0 DRAINAGE BASINS & SUB-BASINS ................................................................. 5
2 . I MAJOR DRAINAGE BASIN DESCRIPTIONS ...................................................... 5
2 .2 SUB-DRAINAGE BASIN DESCRIPTIONS ........................................................... 5
3.0 DRAINAGE DESIGN CRITERIA & CONSTRAINTS ....................................... 6
3 . I STREET DRAINAGE ............................................................................................. 6
3 .2 STORM SEWER INLETS ....................................................................................... 7
3 .3 STORM SEWER SYTEMS ..................................................................................... 7
3 . 4 OPEN CHANNELS ................................................................................................. 8
3.5 CULVERTS ............................................................................................................. 9
3 .6 DETENTION FACILITIES ..................................................................................... 9
4.0 DRAINAGE SYSTEM MODELING .................................................................... 9
4 .I STREET DRAINAGE ........................................................................................... IO
4 .2 STORM SEWERINLETS ..................................................................................... 10
4 .3 STORM SEWER SYSTEMS ................................................................................. IO
4 .4 OPEN CHANNELS ················································'·············································· IO
4 .5 CULVERTS ........................................................................................................... I I
4 .6 DETENTION FACILITIES .................................................... '.· .............................. I l
5.0 CONCLUDED DRAINAGE IMPROVEMENTS ............................................... 11
5.1 STREET DRAINAGE .................. .-........................................................................ 12
5.2 STORM SEWER INLETS ..................................................................................... 12
5 .3 STORM SEWER SYSTEMS ................................................................................. 13
APPENDIX A -HYDRAULIC COMPUTATIONS
APPENDIX B -MAPPING
APPENDIX C -STANDARD DETAILS
__ ...
1
2
3
4
5
/
Sanitary Sewer Improvements:
Engineers Estimate
L.O . Ball Memorial Subd iv ision
College Station , Brazos
March 1999
RECAP
Street & Drainage Improvements:
·'
Water Improvements:
Misc. Construction Items :
Rock Prairie Right Turn :
Sub Total :
Contingency @ 10%:
Total Project Construction :
$39 ,562 .50
$179 ,982.40
$42 ,590 .75
$26 ,700.00
$19 ,170.34
$308 ,005 .99
$30 ,800.60
$338 ,806 .59
J.
....
Item
No.
1
2
3
4
5
6
7
8
9
10
11
Item Name
"8 PVC C900
Class 200 Waterline
w/Class D Embedment
Std . F.H. Type 3
w/Appurtenances
Engineers Estimate
for
L.O . Ball Memorial Subdivision , Phase II
College Station , Brazos County , Texas
March 1999
WATER IMPROVEMENTS
Unit
LF
EA
Gate Valve & Thrust Blocking
8" Gate Valve w/Box EA
24" x 8" M .J . Tap . EA
Sleeve w/Gate Valve
and Thrust Blocking
8" x 8" M .J . Tee EA
w/Conc. Thrust Blocking
8" x 45* Bend EA
w/Concrete Thrust Blocking
2" Underground EA
Blow-off Valve -
w/Thrust Blocking
8" x 90* Bend EA
w/Conc. Thrust Blocking
Tie to Exist 8" Waterline EA
Remove Exist 2"
Blow-off Valve
8" PVC C900 LF
Class 200 Waterline
w/Cement Stab . Backfill
8" x 6" M .J . Reducer EA
Total Water Improvements:
No. CosU Amount
Units Unit
1557 14.75 22965 .75
3 1600 4800
9 400 3600
1 6000 6000
5 450 2250
1 325 325
1 300 300
2 325 650
1 500 500
50 17.5 875
1 325 325
42590.75
Item
No.
1
2
3
4
5
6
7
8
9
Engineers Estimate
fo r
L.O . Ball Memorial Subdivision , Phase II
College Station , Brazos County , Texas
March 1999
SANIT ARY SEWER IMPROVEMENTS
Item Name Un it No .
Units
8" PVC San . Sewer LF 323
SDR-26, Class D . Embedment
0-8' Depth
8" PVC San . Sewer LF 1042
SDR-26 , Class D Embedment
8-10' Depth
Std Manhole EA 2
0-8'Depth
Std Manhole EA 3
8-10' Depth
Drop Manhole EA 1
w/Extra Depth
(Construct over Exist.)
Street Bore w/14" LF 47
Steel Encasement
and 8" DIP Carrier
Pipe
Remove/Back fill EA 1
Exist. Manhole
Plug & Grout LF 550
Exist. 8" VCT
San . Sewer
Trench Safety EA 1
Total Sanitary Sewer Improvements :
Cost/ Amount
Unit
14.5 4683.5
17 17714
1600 3200
1800 5400
2300 2300
95 4465
500 500
2 1100
200 200
39562 .5
Item
No .
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Engineers Estimate
for
L.O. Ball Memorial Subdivision , Phase II
College Station, Brazos County , Texas
March 1999
STREET AND DRAINAGE
Item Name Unit
Street Grading EA
HMAC Surface SY
Course -1-1/2"
(Type D) w/prime coat
8" Crushed Limestone Base SY
6" Lime Stabilized SY
Subgrade (6%)
Post-Construction Seeding of R.O .W . SY
6' Wide Reinf.Concrete Sidewalk LF
(4" Thick)
6" Reinf. Concrete Curb & Gutter LF
Construct Reinforced Cone . Apron EA
Clearing and Grubbing EA
Remove & Dispose Exist 6" Cone . C & G LF
Construct H/C Pedestrian Ramp EA
Demolish & Dispose of Existing Street Stub , Incl. EA
Surface Restoration
Remove and Dispose of Existing 4' Wide Concrete LF
S.W .
Construct Std . Recessed Inlet Box w/8' Aperture EA
Construct Std . Inlet box w/5' Aperture EA
Tie to Exist Inlet Box Restore wall of Inlet Box EA
Remove and Dispose Exist 24" RCP Storm Sewer LF
No . Cost/ Amount
Units Unit
1 13000 13000
5378 3.3 17747.4
6200 4 .3 26660
6200 3.86 23932
1230 0.8 984
2240 14.1 31584
2210 7.5 16575
2 800 1600
1 2000 2000
95 4 380
4 600 2400
1 3700 3700
120 4 480
2 2200 4400
2 1800 3600
1 500 500
95 10 950
17 Proposed Std . Junction Box EA 1 1110 1110
18 24 " R.C .P. Storm Sewer (Class Ill ) LF 443 40 17720
19 30" R.C .P . Storm Sewer (Class Ill) LF 55 51 2805
20 36" R.C .P . Storm Sewer (Class Ill ) LF 50 65 3250
21 Channel Cleaning & Excavation EA 1 1500 1500
(Return to natural grade)
22 B lock Sod Channel SY 50 2 .1 105
Total Street & Drainage : 176982.4
Item
No
1
2
3
4
5
6
Engineers Estimate
for
L.O . Ball Memorial Subdivision , Phase II
College Station , Brazos County , Texas
March 1999
MISC CONSTRUCTION ITEMS
Item Name Unit
Execute Marking and Striping Plan EA
Install Street Lamps, per COCS Std . EA
Install Electrical Conduit across Rock Praire w/Bore EA
Install Street Signs, Bike Path Signs , Stop Signs EA
Erosion Control EA
Traffic Controlffraffic Safety EA
Total Misc . Construction Item :
No. Cost/ Amount
Units Unit
1 2500 2500
5 2800 14000
1 7200 7200
1 600 600
1 1200 1200
1 1200 1200
26700
Item
No .
0
1
2
3
4
5
6
7
9
10
11
12
13
Enginee rs Estimate
for
L.O . Ball Memorial Subdivision , Phase II
College Station , Brazos County , Texas
March 1999
ROCK PRAIRIE RIGHT TURN LANE
(Street items only )
Item Name Unit .
•
Street Grad ing EA
HMAC Surface SY
Course -1-1/2"
(Type D) w/prime coat
8" Crushed Limestone Base SY
6" Lime Stabilized SY
Subgrade (6%)
Post-Construction Block Sodding of R.O .W . SY
6 ' Wide Reinf. Concrete Sidewalk LF
(4 " Thick)
6" Reinf. Concrete Curb & Gutter LF
Construct Reinforced Cone . Apron @ Drive EA
Remove & Dispose Exist 6" Cone . C & G LF
Construct H/C Pedestrian Ramp EA
Demolish & Dispose of Existing Driveway EA
Remove and D ispose of Existing 4 ' Wide Concrete LF
S .W .
Traffic Safety/Traffic Control EA
Total Street & Drainage :
No. Cost/ Amount
Units Unit
1 2000 2000
281 3.3 927 .3
319 4 .3 137 1.7
319 3.86 1231 .34
120 2 .1 252
180 14 .1 2538
180 7 .5 1350
1 800 800
275 4 1100
2 600 1200
1 2000 2000
225 4 900
1 3500 3500
19170 .34
LIST OF TABLES
DESCRIPTION PAGE NO.
TABLE #1 -Sub-Drainage Basin ................................................................................... 6
TABLE #2 -Street Drainage (10-Year) ........................................................................ 12
TABLE #3 -Street Drainage (100-Year) ...................................................................... 12
TABLE #4 -Curb Inlets (10-Year) ............................................................................... 13
TABLE #5 -Curb Inlets (100-Year) ............................................................................. 13
TABLE #6-Storm Sewer System (10-Year) ................................................................ 14
TABLE #7 -Storm Sewer System (100-Year) .............................................................. 14
L.O . Ball Memor ia l Subdivision
Longmire Drive
1.0 PROJECT SCOPE
Municipal Development Group
This report outlines the drainage improvements for the extension of Longmire
Drive through the L.O . Ball Memorial Subdivision. This drainage report will
consist of the requirements necessary for the drainage improvements and
construction of this street in accordance with the provisions of the City of College
Station Drainage Policy and Design Standards .
I. I SITE LOCATION
The street expansion extends through Phase II of the L. 0 . Ball Memorial
Subdivision with Block Two adjacent to the east right-of-way line and
Block Three adjacent to the west right-of-way line. The proposed street
extension will be between and intersect with Rock Prairie Road and
Birmingham Drive. Near by large developments are First National Bank
to the north, College Station Hospital to the west, and the College Station
Utility Service Center to the southwest.
I .2 GENERAL DESCRIPTION
The project will consist of the construction of I , I 60 linear feet of 48 ' BC
to BC street section . This street is classified as a major collector
according to the City of College Station Thoroughfare Plan. The proposed
street will tie into the current intersection of Rock Prairie Road and
Longmire Drive. This intersection is approximately 500 feet southwest of
the intersection of Rock Prairie Road and the West Frontage Road of State
Highway No . 6. The street will extend through the L.O . Ball Memorial
Subdivision, Phase II, being a 27 .50 acre development, and intersect with
Birmingham Road . This proposed intersection is approximately 850 feet
southwest of the intersection of Birmingham Road and the West Frontage
Road of State Highway No . 6 . Adjacent and immediately southwest of
this proposed intersection is an existing intersection with a drainage
system in place . This existing intersection will be demolished, but some
000631-2956 Drainage Report.do c Final Drainage Report - 4 ·
L.O . Ball Memori a l Subdivi sion
Longmire Driv e Municipal Developm ent Group
of the existing drainage structures will be utilized with the proposed
drainage system of the Longmire Drive extension .
2.0 DRAINAGE BASINS & SUB-BASINS
2 .1 MAJOR DRAINAGE BASIN DESCRIPTIONS
The drainage improvements for this project site are contained within the
drainage-watershed of the Lick Creek Drainage Basin . This drainage
basin is illustrated on Exhibit # 1 -"Lick Creek Drainage Basin" located in
Appendix B -Mapping . The borders of this drainage basin roughly
consist of Rock Prairie Road on the north, Wellborn Road to the west and
Alum Creek to the south .
The L. 0 . Ball Memorial Subdivision, Phase II does not lie in the 100-year
floodplain as shown on the Flood Insurance Rate Map , (FIRM) Map No .
48041C0205 C having an effective date of July 2, 1992 . An excerpt of the
FIRM map with the location of the project site is illustrated on Exhibit #2
-"FIRM Map " located in Appendix B -Mapping .
2 .2 SUB-DRAINAGE BASIN DESCRIPTIONS
The proposed improvements will consist of dependent sub-drainage basins
that will collect runoff along different points on the proposed street and
along Birmingham Drive . The total acreage of all the sub-drainage basins
consists of 21.479 acres . An illustration of the sub-drainage basins is
shown on Exhibit #3 -"Sub-Drainage Basin Map" located in Appendix B
-Mapping . From Exhibit #3 the sub-drainage basin areas were
determined along with the weighted coefficient of runoff A summary of
this data is shown below in Table #1 -"Sub-Drainage Basin".
000631-2956 Drainage Report.do c Final Drainage Report -5
L.O . Ba ll Memorial Subdivision
Longmire Drive
TABLE #1 -SUB-DRAINAGE BASIN
Municipal Development Group
DRAINAGE ACREAGE WEIGHTED
AREA ac "C"
A1 3.469 0.42
A2 1.071 0.57
A3 3.501 0.42
A4 4.768 0.40
X1 5.803 0.23
X2 2 .867 0.29
The runoff from these drainage basins will collect in the proposed
drainage system and discharge into the two existing 24" RCP's that cross
under Birmingham Drive. Thence, runoff will continue downstream with
the North Fork of Lick Creek and thence to Lick Creek. The required and
proposed drainage system for the sub-drainage basins is illustrated on
Exhibit #4 -"Proposed Drainage System " located in Appendix B -
Mapping . Results of this drainage system are shown in Section 6 .0 of this
report .
3.0 DRAINAGE DESIGN CRITERIA & CONSTRAINTS
For all development within the City of College Station, there are criteria on the
use of which design storms and development conditions for type of drainage
improvements . Below, in each type of improvement, the required design
constraints are more fully detailed . All drainage improvements shall also be
analyzed during the 100-year rainfall event to insure that no adverse conditions
will exist.
3 .1 STREET DRAINAGE
Street drainage improvements shall be designed in accordance to the City
of College Station's Drainage Policy and Design Standards . Unless
otherwise stated, the following constraints shall dictate the design of all
street grading and drainage :
•:• All proposed streets shall have curb and gutter.
000631-2956 Drainage Report.doc Final Drainage Report -6
L.O . Ball Memorial Subdi vision
Longmire Dri ve Muni ci pal Developm ent Group
•!• Maximum velocity not to exceed 10 ft/sec and minimum slope of
0.4 %.
•!• Concrete valley gutters shall be placed at all roadway intersections
where runoff is carried from one side of the roadway to the other .
•!• The 100-year rainfall event shall be confined within the limits of the
street right-of-way .
•!• All streets permissible spread of water shall be dictated by the 10-year
rainfall event. For each class of street, the following conditions will
control :
)'> Arterial & Parkway-One clear lane in each direction 24 foot total
clearance at center of street.
)'> Collector & Commercial -One clear lane 12 foot total clearance at
the center of the street.
)'> Local -Depth of water not to exceed the top of curb or crown,
whichever is less .
3 .2 STORM SEWER INLETS
Storm sewer inlets shall be designed in accordance to the City of College
Station 's Drainage Policy and Design Standards . Unless otherwise stated ,
the following constraints shall dictate the design of all storm sewer inlets :
•!• Inlets on all streets, except for residential , shall be recessed with a
minimum 4" depression .
•!• Curb openings shall be a minimum length of 5 feet .
•!• Inlets with greater than a 5" gutter depression on streets with less than
a 1. 00% grade shall be designed in sump conditions .
•!• Inlets at bridges and culvert structures shall be oversized to
accommodate 125% of the 10-year rainfall event.
•!• Ponding at curb inlets shall not exceed 18 " in depth .
3 .3 STORM SEWER SYSTEMS
. Storm sewer system improvements shall be designed in accordance to the
City of College Station 's Drainage Policy and Design Standards . Unless
otherwise stated, the following constraints shall dictate the design of all
storm sewer systems :
•!• Minimum velocity allowed is 2 .5-ft/sec and maximum velocity
allowed is 15 ft/sec during the 10-year rainfall event.
•!• When a change in pipe or boxes size is required , the soffit or top
respectively will match and a junction box shall be provided for at
these points .
00063 1-29 56 Drainage Report.doc Final Drainage Re port - 7
L.O . Ball Memorial Subdivision
Longmire Dri ve Muni ci pal Development Group
•:• Maximum spacing of manholes shall be 300 feet for pipes of 54 "
diameter or smaller. Maximum spacing of manhole shall be 500 feet
for pipes greater than 54" diameter .
•:• Minimum storm sewer pipe diameter of 18 ". Short laterals adjacent to
inlets may be 12" in diameter.
•:• Conduits of 24" or less shall be designed with the assumption of a
25% reduction in cross-sectional area.
•:• At all inlets, manholes , and junction boxes an elevation drop of 0 .1
feet minimum will be necessary .
•:• The theoretical hydraulic grade line for the 10-year rainfall event shall
be a minimum of 0 .5 feet from the flowline of any curb inlet in the
system.
•:• The minimum width of any easement for a storm sewer system shall
be 15 feet , and the centerline of the storm sewer shall be at least 5 feet
from the closest side of the easement.
3 .4 OPEN CHANNELS
Open channel improvements shall be designed in accordance to the City of
College Station's Drainage Policy and Design Standards . Unless
otherwise stated, the following constraints shall dictate the design of all
open channels :
•:• Minimum grade shall be 0.4% for earth or vegetative lined channels .
•:• Channel capacities shall be dictated by the design storm of the 25-year
rainfall event.
•:• Low-flow pilot channels shall be required for grass-lined channels
with a carrying capacity of 1/3 of the peak discharge of the 5-year
rainfall event.
•:• Minimum permissible velocity of 2 .5 ft/sec during the 25-year rainfall
event.
•:• Maximum channel velocities shall be as dictated below :
~ Exposed earth at 3 .0 ft/sec .
~ Seeded grass at 4 .5 ft/sec .
~ Sodded grass at 6 .0 ft/sec .
~ Impermeable surface at 10 ft/sec.
•:• Maximum side slope for grass-lined earth channel is 3: 1.
•:• Channels with trapezoidal cross-section shall have a minimum bottom
width of 4 feet.
•:• Channel shall have a minimum freeboard of 0 .5 feet.
•:• The 100-year rainfall event shall be contained within the channel
drainage easement.
•:• Minimum drainage easement width shall be the channel's top width
plus 20 feet.
00063 1-2956 Drainage Report .do c Final Drainage Report -8
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L.O. Ball Me mor ial Subdi vision
Lo ngm ire Dri ve Municipa l D evel opment Group
3 .5 CULVERTS
Culverts shall be designed in accordance to the City of College Station 's
Drainage Pol icy and Design Standards. Unless otherwise stated , the
following constraints shall dictate the design of culverts :
•:• The design discharge for culverts shall be the 25-year rainfall event
unless under a residential street in the secondary drainage system.
Then the 10-year rainfall event will be the design storm .
•:• Maximum headwater elevation shall be one foot less than the top of
curb elevation .
•:• Maximum overflow into the street shall be 2 feet in depth from the
lowest point in the roadway profile . Overflow shall not exceed design
conditions for street drainage .
•:• The maximum allowable discharge into channels are as follows :
);o-Natural channel or seeded cover at 6 .0 ft/sec .
);o-Sodded cover at 8.0 ft/sec .
);o-Impermeable surface at 15 ft/sec.
3 .6 DETENTION
Detention shall be designed in accordance to the City of College Station 's
Drainage Policy and Design Standards . Unless otherwise stated , the
following constraints shall dictate the design of detention basins :
•:• Detention facilities shall have the capacity to contain the 100-year
rainfall event.
•:• Maximum detention basin 's side slope shall be 4 : 1 with vegetative
cover and 2 : 1 for non-vegetative cover.
•:• Bottom slopes of the detention basin with vegetative cover shall be at a
grade of 20 : 1 with low-flow pilot channels .
•:• Minimum of 0 .5 feet of freeboard during the 100-year rainfall event.
•:• Detention facilities other than parking lots and rooftops shall have an
increased capacity of 10% to allow for sedimentation.
4.0 DRAINAGE SYSTEM MODELING
For all drainage system modeling, the volume of runoff will be calculated . The
drainage area calculations are summarized accordingly using the Rational
Method: (Q =CIA) where "Q" is the runoff in cubic feet/second , "C" is the runoff
coefficient, "I" is the storm intensity in inches/hour for each selected frequenc y,
000631-2956 Drainage Report .doc Final Drainage Rep ort • 9
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L.0. Ball Memorial Subdivision
Longmire Dri ve Muni cipal Development Group
and "A" is the drainage area in acres . A mm1mum IO-minute time of
concentration for all calculations will be assumed . The selected frequencies will
be 2 , 5, 10 , 25 , 50, 100-year rainfall events .
4 .1 STREET DRAINAGE
Street flow calculations are aided by the program FlowMaster v . 5.7 by
Haestad Methods . Within this program basic geometry and characteristics
of a proposed or existing curb & gutter street can be defined . From this
information, Manning's formula is then used to calculate desired
parameters of the street.
4.2 STORM SEWER INLETS
Storm sewer inlets are a part of the storm sewer system evaluation . As
mentioned above, this was done with the (TxDOT) hydraulic program
WinStorm v . 1.3 . Derivatives of Manning's formula are used within this
program, pending on the geometry of the curb inlet and the condition of
flow , to size inlets accordingly to the permissible spread of water on the
street.
4 .3 STORM SEWER SYSTEMS
Storm sewer system are evaluated with (TxDOT) hydraulic program
WinStorm v. 1.3. Within this program, basic geometry and characteristics
of a storm sewer system can be defined . This would include data such as
drainage basin calculations, type and configuration of several types of
inlet boxes, and controlling factors of the conveyance system. From this
program critical information can be determined about the storm sewer
system.
4.4 OPEN CHANNELS
Open channel hydraulic calculations are aided by the program FlowMaster
v . 5 .7 by Haestad Methods . Within this program, basic geometry and
000631-2956 Drainage Report.doc Final Drainage Report - I 0 .
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L.O . Ball Memorial Subdivi sion
Longmire Dri ve Municipal Development Group
characteristics of a proposed or existing channel can be defined . From this
information, Manning's formula is then used to calculate desired
parameters of the open channel.
4 .5 CULVERTS
Culverts are evaluated one of two ways :
Short, singular culverts are calculated with the Texas Department of
Transportation (TxDOT) hydraulic program Culverts v . 1.0 . Within this
program, basic geometry and characteristics of a culvert can be defined .
This would included data such as tailwater, geometry, and entrance/exit
losses . For each culvert investigations will be made in order to determine
whether it is inlet or outlet controlled .
For longer more complex culvert with bends and grade transitions the
program StormCad v. 1. 0 by Haestad Methods will be used .
4 .6 DETENTION
Detention requirements are determined by graphical means . Tabulations of
the pre-development and the post-development hydrographs of the
drainage areas are provided . The hydrographs are based on the standard
SCS unit hydrograph with time to peak discharge set to equal the time of
concentration and the total base time set at 3. 00 times the time of
concentration .
5.0 CONCLUDED DRAINAGE IMPROVEMENTS
The proposed drainage system for the Longmire Drive extension consists of the
analysis of three design criteria. These three items being street drainage, curb
inlets & and the actual conveyance system . Below are the summary data of the
designed drainage system .
000631-2956 Drainage Report.do c Final Drainage Report -11
I
I
L.O . Ball Memorial Subdivision
Longmire Dri ve Muni ci pal Development Group
5.1 STREET DRAINAGE
The proposed extension of Longmire Drive was designed for the 10-year
rainfall event and was analyzed with the 100-year rainfall event. As
shown below in Table #2 & #3 , the proposed street has the capacity to
carry the 10-year rainfall event within the curb & gutter section and
provide for a 12 ' clear lane at the center of the proposed street. Also, the
proposed street 's curb & gutter cross-section will carry the 100-year
rainfall event without overflowing into the 70' right-of-way.
TABLE #2 -STREET DRAINAGE (10-YEAR)
DISCHARGE CURB CLEAR LANE WIDTH
D.A. SLOPE RUNOFF VELOCITY DEPTH RIGHT LEFT TOTAL
% cf s ft/sec ft ft ft ft
LONGMIRE DRIVE
A1 0.96 12 .580 3.91 0.37 5.42
A2 0.96 5.271 3.15 0.27 10.58
A3 1.52 13.535 4 .73 0.35 6.42
A4 1.52 19 .756 5.20 0.41 4.31 10.73
TABLE #3-STREET DRAINAGE (100-YEAR)
DISCHARGE CURB
D.A. SLOPE RUNOFF VELOCITY DEPTH
% cf s ft/sec ft
LONGMIRE DRIVE
A1 0.96 16.958 4 .21 0.42
A2 0.96 7.105 3.39 0.30
A3 1.52 18.843 5.14 0.40
A4 1.52 27 .969 5.67 0.46
5.2 STORM SEWER INLETS
Below is a summary of the existing curb inlets along Birmingham Drive
and the proposed curb inlets along Longmire Drive. These proposed curb
inlets were designed and the existing inlets were evaluated under the
proposed conditions during a 10-year rainfall event. The 100-year rainfall
event was also analyzed, and the summary for both these rainfall events
are below. For design information on the proposed drainage system 's curb
000631-2956 Drainage Report.do c Final Drainage Report -12
I
I
L.O. Ball Me mor ial Subd ivision
Longmire Dri ve Muni ci pal Developm ent Group
inlets refer to the calculation reports m Appendix A -"Hydraulic
Computations".
TABLE #5-CURB INLETS (100-YEAR)
CURB
l.D.
A1
A2
A3
A4
X1
X2
5.3
OPEN CURB DIFF. PONDING TOTAL INLET
SIZE FLOWLINE (FL-HGL) WIDTH DEPTH Q CAPACITY
ft ft ft ft ft cf s cf s
LONGMIRE DRIVE
8 303 .730 302.106 1.624 14 .566 0.46 16 .958 8.825
8 303 .630 301 .825 1.805 10 .605 0 .33 7 .105 5.377
5 297.760 297.419 0 .341 16 .134 0 .84 18 .843 18 .674
5 296 .790 296 .951 -0 .161 12.300 0 .72 27 .969 35.014
BIRMINGHAM DRIVE
5 297.000 296.555 0.445 17 .923 0.89 12.989 11 .671
5 297 .000 295 .534 1.466 12 .875 0.73 9.677 11 .671
STORM SEWER SYSTEMS
Below is a summary of the proposed and existing storm sewer conveyance
· elements during the I 0-year rainfall event. The I 00-year rainfall event
was also analyzed, and is summarized below . For design information on
the proposed drainage system 's con veyance des ig n refer to the calculation
reports in Appendi x A -"H ydraulic Computations".
000631-29 56 Drainage Report .d oc Final Drainage Report -13
I
I
L.O . Ba ll Me mori al Su b division
Lo n gm ire Drive Muni cipal D evelopment Gro.up
TABLE #6-STORM SEWER SYSTEM (10-YEAR)
PIPE CONDUIT MAX TOTAL
RUN SIZE GRADE HGL VELOCITY a
l.D. in % ft ft/sec cf s
LONGMIRE DRIVE
1 24 0.840 300.324 5.73 12 .580
2 24 0 .852 300.097 7.46 17 .763
3 24 0 .853 297.370 5 .65 20.893
4 30 0.840 296.322 5 .98 29 .348
5 36 0 .855 296 .066 5 .93 41 .922
BIRMINGHAM DRIVE
6 24 0 .813 295 .849 7 .76 48.773
7 24 1.000 295 .291 8 .69 54 .576
TABLE #7 -STORM SEWER SYSTEM (100-YEAR)
PIPE CONDUIT MAX TOTAL
RUN SIZE GRADE HGL VELOCITY a
l.D.
1
2
3
4
5
6
7
m % . ft ft/sec cf s
LONGMIRE DRIVE
24 0 .840 302.106 5.40 16 .958
24 0 .852 301 .825 7 .62 23 .953
24 0 .853 299 .325 7 .62 23 .953
30 0.840 297.419 8.08 39.661
36 0 .855 296 .951 8 .01 56 .631
BIRMINGHAM DRIVE
24 0 .813 296 .555 10 .50 65 .982
24 1 .000 295 .534 11 .76 73 .900
Existing pipe runs #6 & #7 are double barrel 24" RCP 's and ar<.e
analyzed as such in the hydraul ic computations.
The permissible discharge velocity in to a natural creek bed is 0 .. 0
ft/sec . Since the proposed drainage system and street
improvements will increase this discharge velocity up to 8 .69 ft/sec
the existing channel banks and flowlines will need to be blook
sodded to a point approximatel y 20 ' downstream .
000631-2956 Drainage Rep ort .doc Rina1 Drainage Report-Il'4
I
I
000631-2956 Drainage Report.do c
APPENDIX A
HYDRAULIC COMPUTATION
WinStorm
JOB CONTROL
JOB SECTION
JOB NUMBER
TxDOT STORM DRAIN DESIGN
A
631
2956
2 956T1RA .out
Version 1.3 September 1997 PAGE 1
Fri Feb 26 14:23:08 1999
PROJECT DESCRIPTION : .L.O. BALL SUBDIVISION
DESIGN FREQUENCY 10 Year
MEASUREMENT UNITS: Input ENGLISH Output ENGLISH
Runoff Computations
I.D.
A 1
x 1
A 2
x 2
A 3
A 4
D
WinStorm
C Value
0.420
0.230
0.570
0.290
0.420
0.400
Area
(acres)
3.469
5.803
1. 071
2.867
3.501
4.768
Tc
(min)
10.00
15.00
10.00
10.00
10.00
13.00
TxDOT STORM DRAIN DESIGN
On-Grade Inlet Configuration Data
Inlet Slopes
Tc Used
(min)
10.00
15.00
10.00
10.00
10.00
13.00
Intensity Supply Q
(in/hr) (cfs)
8.635 0.000
7.194 0.000
8.635 0.000
8.635 0.000
8.635 0.000
7.699 0.000
Total Q
(cfs)
12.580
9.602
5.271
7.179
12.696
14.684
Version 1.3 September 1997 PAGE 2
Fri Feb 26 14:23:08 1999
Gutter Grate Pond Width Critical Inlet
I. D.
Inlet
Type Length Long. Trans. n Depr. Length Type Allowed Elev.
A 1
A 2
CURB
CURB
(ft) (%) (%) (ft) (ft)
8.000
8.000
0.96 3.13 0.014 0.330 n/a
0.96 3 .1 3 0.014 0.330 n/a
Page 1
n/a
n/a
(ft)
17.000
17.000
303.230
303.130
2 9 56T1RA.out
D
WinS t orm TxDOT STORM DRAIN DE S IGN Versi o n 1.3 S e ptember 1 9 97 PAGE 3
F r i Fe b 26 14:2 3:08 1999
On-Grade Inlet Computation Data
Inle t
I. D .
A 1
A 2
D
Inlet
Type
CURB
CURB
WinStorm
Total
Q
(cfs)
12 .580
5 .271
Inl e t
Capacity
(cfs)
7.508
4.433
Total
Carryov er
(cfs)
5.07 2
0.839
TxDOT STORM DRAIN DESIGN
To
Inlet
A 4
A 3
Re quire d
Le ngth
(ft)
20.187
12.503
Ac tual
Length
(ft)
8.000
8 .000
Ponde d
Width
(ft)
13.065
9.518
Version 1.3 September 1997 PAGE 4
Fri Feb 26 14:23:09 1999
Sag Inlet Configuration Data
Inlet
I. D.
x 1
x 2
A 3
A 4
D
Inlet
Type
CURB
CURB
CURB
CURB
Length/ Grate Left
Perim. Area Long
(ft) (sf) (%)
5 .000 n/a 1. 00
5.000 n/a 1. 00
8.000 n/a 1. 5 2
10 .000 n/a 1. 5 2
Slope Right Slope
Trans Long Trans
(%) (%) (%)
2 .54 1. 00 2.54
2.54 1. 00 2.54
3.13 1. 00 3.13
3 .13 1. 00 3.13
Gutter Depth
n Depr . Allow
(ft) (ft)
0 .014 0 .330 0 .500
0 .014 0 .330 0.500
0.014 0.330 0.500
0 .014 0.330 0.500
Cr itical
Elev.
296 .500
296.500
297.260
296 .290
WinStorm TxDOT STORM DRAIN DESIGN Version 1.3 September 1997 PAGE 5
Sag Inlet Computation Data
Inlet Inlet
I.D . Type
Length/ Grate
Per im. Area
To t al
Q
Inlet Total
Capaci ty He a d
Pa ge 2
Fri Feb 26
Ponded Widths
Left Righ t
14:23 :09 1999
--
x 1
x 2
A 3
A 4
0
CURB
CURB
CURB
CURB
(f t)
5.0 00
5.000
8 .000
1 0 .0 0 0
(sf )
n/a
n/a
n/a
n/a
(cfs )
9 .602
7.179
13 .535
19 .75 6
2956T l RA .ou t
(c f s)
11.67 1
11.6 7 1
1 8.674
23 .343
(f t)
0 .7 29
0 .600
0 .670
0 .743
(f t )
10.31 8
9 .295
9 .582
10 .988
(f t)
1 0 .318
9 .295
10 .3 17
1 1.85 1
WinStorm TxDOT STORM DRAIN DESIGN Ver s ion 1.3 September 1 9 97 PAGE 6
Cumulative Junction Discharge Computations
Node
I. D.
Al
Jl
Xl
A2
X2
A3
A4
0
Weighted
C-Value
0.420
0.455
0.364
0.455
0.354
0.440
0.425
Cumulative
Drainage Area
(acres)
3.46 9
4.540
18.612
4.540
21.479
8.041
12.809
Cumulative
Tc
(min)
10 .00
10.12
15.00
10.12
15.10
11. 00
13.00
WinStorm TxDOT STORM DRAIN DESIGN
Conveyance Configuration Data
Flowli n e E lev.
Intensity
(in/hr)
8.635
8.592
.7.194
8. 592
7.171
8.2 9 5
7.699
Version 1 .3
Fri Feb 2 6 14:23:09 1999
Supplied
Discharge
(cfs)
0.000
0.000
0.000
0.000
0.000
0.000
0.000
Total
Discharge
(cfs)
12.580
17. 763
48.773
17.763
54.576
29.348
41.922
September 1997 PAGE 7
Fri Feb 2 6 14:23:09 1999
Run
I. D.
Node I.D.
US DS US DS Shape # Span
(ft)
Ri se
(ft)
Length
(ft)
Slope
(%)
n
1 Al A2 299 .200 29 8.78 0 Circ 1 n/a 2 .000 5 0 .0 0 0.840 0 .013
Pa g e 3
--
-2956T1RA.out
2 A2 Jl 298.680 296 .780 Circ 1 n/a 2 .000 223.00 0.852 0.013
3 Jl A3 295.680 294.230 Circ 1 n/a 2 .000 170.00 0.853 0.013
4 A3 A4 293.630 293 .210 Circ 1 n/a 2 .500 50.00 0.840 0.013
5 A4 Xl 292 .610 292 .140 Circ 1 n/a 3 .000 55.00 0.855 0.013
6 Xl X2 293 .040 292 .6 50 Circ 2 n/a 2 .000 48.00 0.813 0.013
7 X2 J2 292.650 292.450 Circ 2 n/a 2 .0 00 20 .00 1.000 0.013
D
WinStorm TxDOT STORM DRAIN DESIGN Version 1.3 September 1997 PAGE 8
Fri Feb 2 6 14:23:09 1999
------------------------------------------------------------------------------
Conveyance Hydraulic Computations
------------------------------------------------------------------------------
Hydraulic Gradeline Depth Velocity June
Run us Elev OS Elev Slope Unif. Actual Unif. Actual Q Cap Loss
(%) (ft) (ft) (fps) (fps) (cfs) (cfs) (ft)
------------------------------------------------------------------------------
1 300.324 300.097 0.31 1.124 1. 317 6.92 5.73 12.580 20.734 0.000
2 300.097 297.370 0.62 1.417 1.417 7 .47 7 .46 17.763 20.882 0.000
3 297.370 296.322 0.62 1. 417 2.000 7.47 5.65 17.763 20.893 0.000
4 296.322 296.066 0.51 1. 662 2.500 8 .47 5.98 29.348 37.593 0.000
5 296 .066 295.849 0.40 1. 815 3.000 9 .37 5 .93 41. 922 61.658 0.000
6 295.849 295.291 1.16 1. 875 2.000 7 . 97 7 .76 48.773 40.784 0.000
7 295.291 295.000 1. 46 1. 875 2.000 8.92 8.69 54.576 45 .246 0.000
D
Win Storm TxDOT STORM DRAIN DESIGN Version 1.3 September 1997 PAGE 9
Computation Messages
*Warning: Capacity of grade inlet id Al exceeded.
*Warning: Capacity of grade inlet id A2 exceeded.
Fri Feb 26 14:23:09 1999
*Warning: Discharge decreased downstream Junction Jl -previous intensity used
*Warning: Decreasing Conduit Size -Downstream Run 6 was adjusted .
*Computation: Run = 3 -Pipe Flowing Full
Page 4
--
---29 56TlRA .out
*Computation: Run 4 -Pipe Flowing Full
*Computation: Run 5 -Pipe Flowing Full
*Computation: Run 6 -Insufficient Capacity
*Computation: Run 7 -Insufficient Capacity
NORMAL Completion of WinStorm.
Page 5
WinStorm TxDOT STORM DRAIN DESIGN
JOB CONTROL A
JOB SECTION 631
JOB NUMBER 2956
-2 956TlRA.out
Version 1.3 September 1997 PAGE 1
Fri Feb 26 14:30:59 1999
PROJECT DESCRIPTION : L.O . BALL SUBDIVISION
DESIGN FREQUENCY 100 Year
MEASUREMENT UNITS: Input ENGLISH Output ENGLISH
Runoff Computations
I. D.
A 1
x 1
A 2
x 2
A 3
A 4
D
WinStorm
C Value
0.420
0.230
0.570
0.290
0.420
0.400
Area
(acres)
3.469
5.803
1. 071
2.867
3.501
4.768
Tc
(min)
10.00
15.00
10.00
10.00
10.00
13.00
TxDOT STORM DRAIN DESIGN
On-Grade Inlet Configuration Data
Inlet Slopes
Tc Used
(min)
10.00
15.00
10.00
10.00
10.00
13.00
Intensity Supply Q
(in/hr) (cfs)
11. 63 9 0.000
9.732 0.000
11. 639 0.000
11. 639 0.000
11.639 0.000
10.400 0.000
Total Q
(cfs)
16.958
12.989
7.105
9.677
17.114
19.836
Version 1.3 September 1997 PAGE 2
Fri Feb 26 14:31:00 1999
Gutter Grate Pond Width Critical Inlet
I. D.
Inlet
Type Length Long. Trans. n Depr. Length Type Allowed Elev.
A 1
A 2
CURB
CURB
(ft) (%) (%) (ft) (ft)
8.000
8.000
0.96 3.13 0.014 0.330 n/a
0.96 3 .1 3 0.014 0.330 n/a
Page 1
n/a
n/a
(ft)
17.000
17.000
303.230
303.130
--2 956 T 1RA.out
0
WinStorm TxDOT STORM DRAIN DESIGN Version 1.3 September 1997 PAGE 3
Fri Feb 2 6 14:31:00 1999
On-Grade Inlet Computation Data
Inlet
I. D.
A 1
A 2
0
Inlet
Type
CURB
CURB
WinStorm
Total
Q
(cfs)
16.958
7.105
Inlet
Capacity
(cfs)
8.825
5.377
Total
Carryover
(cfs)
8.133
1.729
TxDOT STORM DRAIN DESIGN
To
Inlet
A 4
A 3
Required
Length
(ft)
23.868
14.705
Actual
Length
(ft)
8.000
8.000
Ponded
Width
(ft)
14.566
10.605
Version 1.3 September 1997 PAGE 4
Fri Feb 26 14:31:00 1999
Sag Inlet Configuration Data
Inlet
I. D.
x 1
x 2
A 3
A 4
0
Inlet
Type
CURB
CURB
CURB
CURB
Length/ Grate Left
Perim. Area Long
(ft) (sf) (%)
5.000 n/a 1. 00
5.000 n/a 1. 00
8.000 n/a 1. 52
15.000 n/a 1. 52
Slope Right Slope
Trans Long Trans
(%) (%) (%)
2.54 1. 00 2.54
2.54 1. 00 2.54
3.13 1. 00 3.13
3.13 1. 00 3.13
Gutter Depth
n Depr. Allow
(ft) (ft)
0.014 0.330 0.500
0.014 0.330 0.500
0 .014 0.330 0.500
0 .014 0.330 0.500
Critical
Elev.
296.500
296.500
297.260
296.290
WinStorm TxDOT STORM DRAIN DESIGN Version 1.3 September 1997 PAGE 5
Sag Inlet Computation Data
Inlet Inlet
I.D. Type
Length/ Grate
Perim. Area
Total
Q
Inlet Total
Capacity Head
Page 2
Fri Feb 26 14:31:00 1999
Ponded Widths
Left Right
x 1
x 2
A 3
A 4
D
CURB
CURB
CU RB
CURB
(f t ) (sf)
5.0 00 n/a
5 .000 n/a
8 .000 n/a
15.00 0 n/a
(cfs)
1 2 .989
9 .6 7 7
18 .8 4 3
2 7.9 6 9
2956TlRA.o ut
(c f s)
11.6 7 1
11.6 71
18 .6 74
35 .0 14
(ft)
0.89 1
0 .733
0 .8 35
0 .71 5
(f t ) (ft)
11.53 9 11.539
1 0 .3 58 1 0 .3 5 8
10 .7 96 11 .6 5 9
1 2 .4 90 1 3 .480
--
WinStorm TxDOT STORM DRAIN DESIGN Ve rsion 1.3 September 1997 PAGE 6
Cumulative Junction Discharge Computations
Node
I. D .
Al
Jl
Xl
A2
X2
A3
A4
D
Weighted
C-Value
0.4 2 0
0.455
0.364
0.455
0.354
0.440
0.425
Cumulative
Drainage Area
(acres)
3.46 9
4.540
18 .612
4.540
21. 479
8.041
12.809
Cumulative
Tc
(min)
10.00
10.11
15.00
10.11
1 5 .07
10.95
13.00
WinStorm TxDOT STORM DRAIN DESIGN
Conveyance Configuration Data
Flowlin e Ele v .
Intensity
(in/hr)
11. 63 9
11.586
9 .732
11.586
9 .709
11.2 10
10 .400
Vers i on 1.3
Fri Feb 26 14:31:00 1999
Supplied
Discharge
(cfs)
0.000
0.0 0 0
0 .000
0 .000
0.000
0 .000
0.000
Total
Discharge
(cfs)
16.958
23.953
65 .982
23.953
73.900
39.661
56.631
Sep temb e r 1997 PAGE 7
Fri Feb 2 6 14:31:00 1999
Run
I.D.
Node I.D.
US DS US DS Shape # Span
(ft)
Rise
(ft)
Length
(ft)
Slope
(%)
n
1 Al A2 299 .200 298 .7 80 Cir c 1 n/a 2 .000 50 .00 0.840 0 .0 13
Page 3
---29 56T1RA.out
2 A2 Jl 2 98.68 0 29 6.78 0 Cir c 1 n/a 2 .0 0 0 223 .0 0 0.852 0.013
3 Jl A3 29 5.68 0 29 4.2 3 0 Cir c 1 n/a 2 .000 1 70 .00 0.853 0.013
4 A3 A4 29 3.63 0 293 .2 1 0 Cir c 1 n/a 2.50 0 50.0 0 0.840 0.013
5 A4 Xl 292 .61 0 292 .14 0 Circ 1 n/a 3 .000 5 5.00 0 .8 55 0.013
6 Xl X2 293 .04 0 292 .650 Circ 2 n/a 2 .000 48.00 0 .813 0.013
7 X2 J 2 2 9 2 .650 292 .450 Circ 2 n /a 2 .000 20 .00 1.000 0.013
0
Wi n Sto rm Tx DOT STORM DRAIN DESIGN Ve r s ion 1. 3 Sep temb e r 1 99 7 PAGE 8
Fri Feb 26 1 4:3 1:01 1999
------------------------------------------------------------------------------
Conveyance Hydraulic Computations
------------------------------------------------------------------------------
Hydraulic Gradeline Depth Velocity June
Run us Elev DS Elev Slope Unif . Actual Unif. Actual Q Cap Loss
(%) (ft) (ft) (fps) (fps) (cfs) (cfs) (ft)
------------------------------------------------------------------------------
1 302.106 301.825 0.56 1. 375 2.000 7.36 5.40 16.958 2 0.734 0.000
2 301.825 299.325 1.12 1.875 2 .000 7.83 7. 6 2 2 3.953 2 0.882 0.000
3 299.325 297.419 1.1 2 1. 875 2 .000 7.83 7. 6 2 2 3.953 2 0.893 0.000
4 297.419 296.951 0.94 2.203 2.500 8.66 8.08 39.661 37.593 0.000
5 296.951 296.555 0.72 2. 264 3.000 9.90 8.01 56.631 61.658 0.000
6 296.555 295.534 2.13 1. 875 2.000 10.78 10.50 65.98 2 40.784 0.000
7 295.534 295.000 2. 67 1.875 2 .000 1 2 .08 11.76 73.9 00 45.246 0.000
0
WinStorm TxDOT STORM DRAIN DESIGN Version 1.3 September 1997 PAGE 9
Fri Feb 2 6 14:31:01 1999
Computation Messages
*Warning: Capacity of grade inlet id Al e x ceeded.
*Warning: Capacity of grade inlet id A2 e x ceeded.
*Warning: Capacity of sag inlet id x 1 e x ceeded.
*Warning: Capacity of sag inlet id A 3 e x ceeded .
*Warning: Left ponded width e xc eeds allowabl e wi dth at inlet id A4.
Page 4
--2956T1RA.out
*Warning: Right ponded width exceeds allowable width at inlet id A4.
*Warning: Discharge decreased downstream Junction Jl -previous intensity used
*Warning: Decreasing Conduit Size -Downstream Run 6 was adjusted.
*Warning: Run -6 -Upstream Hydraulic Gradelin e 296 .55 -Exceeds Critical Elevation 29 6
.50
*Warning: Run - 5 -Upstream Hydraulic Gradeline
.29
*Warning: Run -4 -Upstream Hydraulic Gradeline
.26
*Computation: Run 1 -Pipe Flowing Full
*Computation: Run 2 -Insufficient Capacity
*Computation: Run 3 -Insufficient Capacity
*Computation: Run 4 -Insufficient Capacity
*Computation: Run 5 -Pipe Flowing Full
*Computation: Run 6 -Insufficient Capacity
*Computation: Run 7 Insufficient Capacity
NORMAL Completion of WinStorm.
Page 5
296 .95 -Exceeds Critical Elevation 296
297.42 -Exceeds Critical Elevation 297
l
I
I
I
APPENDIX A
Worksheet for Irregular Channel
Project Description
untitted.fm2 Project File
Worksheet
Flow Element
Method
Longmire Dr. DA: A 1 (10 yr)
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 0.96 %
Elevation range: 0.00 ft to 0.50 ft .
Station (ft) Elevation (ft)
0 .00 0.50
0 .50
0 .50
23 .50
Discharge
Results
Wtd. Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top Width
Height
Critical Depth
0 .50
0.00
0.50
12 .580 cfs
0.012
0.37
3.22
17.58
17 .20
0.37
0.45
ft
ft2
ft
ft
ft
ft
Critical Slope 0.003550 ft/ft
Velocity 3.91 ft/s
Velocity Head 0.24 ft
Specific Energy 0.61 ft
Froude Number 1.59
Flow is supercritical.
Start Station
0 .00
Municipal Development Group
End Station
23 .50
02126/99
03 :38:42 PM Haestad Methods, Inc . 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0.012
FlowMaster v5 .07
Page 1 of 1
I
I
I
APPENDIX A
Worksheet for Irregular Channel
Project Description
untitled.fm2 Project File
Worksheet
Flow Element
Method
Longmire Dr. DA: A 1 ( 100 yr)
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 0.96 %
Elevation range: 0.00 ft to 0.50 ft.
Station (ft) Elevation (ft)
0 .00 0.50
0.50
0.50
23 .50
Discharge
Results
Wtd . Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top Width
Height
Critical Depth
0.50
0 .00
0 .50
16 .958 cfs
0 .012
0.42
4 .02
19 .67
19 .24
0.42
0.51
ft
ft2
ft
ft
ft
ft
Start Station
0.00
Critical Slope 0.003416 ft/ft
Velocity 4.21 ft/s
Velocity Head 0.28 ft
Specific Energy 0.69 ft
Froude Number 1.62
Flow is supercritica l.
Municipal Development Group
End Station
23 .50
02/26/99
03 :39 :00 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0.012
FlowMaster vS .07
Pag e 1 of 1
J
I
I
I
APPENDIX A
Worksheet for Irregular Channel
Project Description
Project File
Worksheet
Flow Element
Method
i:\projects\600\2956 -lbms\2956t1 ra.fm2
Longmire Dr. DA: A2 (10 yr)
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 0.96 %
Elevation range: 0 .00 ft to 0.50 ft.
Station (ft) Elevation (ft)
0 .00 0.50
0.50 0.50
0.50 0.00
23 .50
Discharge
Results
Wtd . Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top Width
Height
Critical Depth
0 .50
5.271 cfs
0.012
0.27
1.68
12 .69
12 .42
0.27
0.32
ft
ft2
ft
ft
ft
ft
Start Station
0.00
Critical Slope 0.003986 ft/ft
Velocity 3.15 ft/s
Velocity Head 0.15 ft
Specific Energy 0.42 ft
Froude Number 1.51
Flow is supercritical.
Municipal Development Group
End Station
23 .50
02/26/99
03:41 :52 PM Haestad Methods, Inc . 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0.012
FlowMaster v5 .07
Page 1 of 1
I
I
APPENDIX A
Worksheet for Irregular Channel
Project Description
Project File
Worksheet
Flow Element
Method
i :\projects\600\2956 -lbms\2956t1 ra.fm2
Longmire Dr. DA: A2 (100 yr)
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 0.96 %
Elevation range : 0.00 ft to 0.50 ft.
Station (ft) Elevation (ft)
0 .00 0.50
0.50
0.50
23 .50
Discharge
Results
Wtd. Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top Width
Height
Critical Depth
0.50
0.00
0.50
7.105cfs
0.012
0.30
2.10
14.19
13.89
0.30
0.36
ft
ft2
ft
ft
ft
ft
Start Station
0.00
Critical Slope 0.003831 ft/ft
Velocity 3.39 ft/s
Velocity Head 0.18 ft
Specific Energy 0.48 ft
Froude Number 1.54
Flow is supercritical.
Municipal Development Group
End Station
23 .50
02126 /99
03:42:27 PM Haestad Methods , Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0.012
FlowMaster v5 .07
Page 1 of 1
I
I
APPENDIX A
Worksheet for Irregular Channel
Project Description
Project File
Worksheet
Flow Element
Method
i:\projects\600\2956 -lbms\2956t1 ra.fm2
Longmire Dr. DA: A3 (10 yr)
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 1.52 %
Elevation range : 0 .00 ft to 0.50 ft.
Station (ft) Elevation (ft)
0 .00 0.50
0.50
0 .50
23 .50
Discharge
Results
Wtd . Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top W idth
Height
Critical Depth
0.50
0 .00
0 .50
13 .535 cfs
0.012
0.35
2 .86
16 .58
16 .22
0.35
0.46
ft
ft2
ft
ft
ft
ft
Start Station
0.00
Critical Slope 0.003515 ft/ft
Velocity 4.73 ft/s
Velocity Head 0.35 ft
Specific Energy 0.70 ft
Froude Number 1.99
Flow is supercritical.
Municipal Development Group
End Station
23 .50
02/26/99
03 :43 :24 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0.012
FlowMaster v5 .07
Page 1 of 1
APPENDIX A
Worksheet for Irregular Channel
Project Description
Project File
Worksheet
Flow Element
Method
i:\projects\600\2956 -lbms\2956t1 ra .fm2
Longmire Dr. DA: A3 (100 yr)
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 1.52 %
Elevation range: 0.00 ft to 0.50 ft.
Station (ft) Elevation (ft)
0.00 0.50
0 .50
0.50
23 .50
Discharge
Results
Wtd . Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top W idth
Height
Critical Depth
0.50
0.00
0 .50
18 .843 cfs
0.012
0.40
3.67
18 .77
18 .37
0.40
0.53
ft
ft2
ft
ft
ft
ft
Start Station
0.00
Critical Slope 0.003344 ft/ft
Velocity 5.14 ft/s
Velocity Head 0.41 ft
Specific Energy 0.81 ft
Froude Number 2.03
Flow is supercritical.
Municipal Development Group
End Station
23 .50
02126199
03 :44:06 PM Haestad Methods, Inc . 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0 .012
FlowMaster v5 .07
· Page 1 of 1
I
I
I
I
I
APPENDIX A
Worksheet for Irregular Channel
Project Description
Project File
Worksheet
Flow Element
Method
i :\projects\600\2956 -lbms\2956t1 ra.fm2
Longmire Dr. DA : A4 (10 yr}
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 1.52 %
Elevation range: 0 .00 ft to 0 .50 ft.
Station {ft} Elevation {ft}
0 .00 0 .50
0 .50
0 .50
23 .50
Discharge
Results
Wtd . Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top W idth
Height
0 .50
0.00
0 .50
19 .756 cfs
0.012
0.41
3.80
19 .11
18 .69
0.41
0.54
ft
ft2
ft
ft
ft
ft
Start Station
0 .00
Critical Depth
Critical Slope
Velocity
0.003312 ft/ft
Velocity Head
Specific Energy
Froude Number
Flow is supercritical.
5.20
0.42
0 .83
2 .03
ft/s
ft
ft
Municipal Development Group
End Station
23 .50
02126/99
03 :44:45 PM Haestad Methods , Inc . 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0 .012
FlowMaster v5 .07
Page 1 of 1
I
I
I
I
APPENDIX A
Worksheet for Irregular Channel
Project Description
Project File
Worksheet
Flow Element
Method
i :\projects\600\2956 -lbms\2956t1 ra.fm2
Longmire Dr. DA: A4 (100 yr)
Irregular Channel
Manning's Formula
Solve For Water Elevation
Input Data
Channel Slope 1.52 %
Elevation range: 0.00 ft to 0 .50 ft.
Station (ft) Elevation (ft)
0 .00 0.50
0.50 0 .50
0.50
23 .50
Discharge
Results
Wtd. Mannings Coefficient
Water Surface Elevation
Flow Area
Wetted Perimeter
Top Width
Height
Critical Depth
0 .00
0 .50
27 .969 cfs
0 .012
0 .46
4 .93
21 .77
21 .30
0 .46
0.61
ft
ft2
ft
ft
ft
ft
Start Station
0 .00
Critical Slope 0.003091 ft/ft
Velocity 5.67 ft/s
Velocity Head 0.50 ft
Specific Energy 0 .96 ft
Froude Number 2.08
Flow is supercritical.
Municipal Development Group
End Station
23 .50
02126/99
03:45:18 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
Roughness
0 .012
FlowMaster v5 .07
Page 1 of 1
000631-2956 Drainage Report .doc
APPENDIXB
MAPPING
DESCRIPTION
APPENDIXB
TABLE OF CONTENTS
PAGE NO.
Exhibit #1 -Lick Creek Drainage Basin ...................................................................... B-1
E xhibit #2 -FIRM Map .............................................................................................. B-2
Exhibit #3 -Sub-Drainage Basin Map ........................................................................ B-3
Exhibit #4 -Proposed Drainage System ...................................................................... B-4
00063 1-2 956 Drain age Report.do c
000631-2956 Drainage Report.doc
APPENDIXC
STANDARD DETAILS
DESCRIPTION
APPENDIXC
TABLE OF CONTENTS
PAGE NO.
Typical 47' Street Section ........................................................................................... C-1
Typical Curb & Gutter Section .................................................................................... C-2
Concrete Valley Gutter@ Intersection ........................................................................ C-3
Typical Valley Gutter Cross Section ............................................................................ C-4
Recessed Curb Inlet .................................................................................................... C-5
Junction Box ............................................................................................................... C-6
Standard Curb Inlet ..................................................................................................... C-7
000631 -2 956 Drainage Report .d oc
2'---efio-------21.5'--------
1 ~" TYPE "D" ASPHALT SURFACE COURS
LIME-STABILIZED SUBGRADE
TYPICAL CURB & GUTTER
6" FLEXIBLE BASE (CRUSHED LIMESTONE)
TYPICAL 47' STREET SECTION
(NTS)
TYPICAL CURB AND GUTTER
SECTION
(NTS)
#4 BARS, @ 24" O.C .E.W.
4'-6" 1 '-6"
6'-0"
SECTION A-A
CONC .
APRON
24"
II
R.P. :
CONCRETE
VALLEY GUTIER
A
0
I
0
~
~ ~-. ·.·
··.·: · ..
. . : . : ........ : .. ~. ~ . ... .. .... ,· .
.. ·. . . ~ ~ '. .
A
· ..
TYPE "G"
EXPANSION JOINT
#4 BARS, @ 24" O.C.E .W.
TYPE "G"
EXPANSION JOINT
CONCRETE VALLEY GUTTER @ INTERSECTION
N.T.S.
---ll"'-------11F-I" ---1
.....________.J· ---= --
3~ ~ l.OltGITllDllW. 1/2" DIA. 10" C.TO C.7 , l· TUNSYtRS£ 1 /2" DIA. 18" c. TO c.
-----3'-o=-· -----
TYPICAL VALLEY GUTTER
CROSS SECTION
(HTS)
1 O' TitANSITION f'OR GUTTER DEPRESSION
MOTE1 WHERE SIDEWALK AllllTS INLET BOX
t12• DIA. ST£El REINf'ORCEMENT SHAU. BE
5"u88m OUT A MINIMUM Of' 12• e s• O.C.
OR AS STll'Ul.ATED BY THE DtGINEElt.
MINFORCING STitl 14 SIO£WAU< SMAll THl:N
BE TIED TO BOX AND EXTENSION STEEL.
10' TRANSITION f'OR GUTTER DEPRES!ION
ELEVATION OF RECESSED CURB INLET
{HTS)
O.D + 1' -g• W\14.~· -0
PLAN OF RECESSED CURB INLET
10' lltA f'Oll GUTTEJt
1 O' TRANSITION FOR GUTTER DEPRESSION
.. :···· :~~---:..r:·:• .. ::s--ii .l '··:·· ... ·· I :<':I~._::
-'1-----1 Ii I I
NOTE:
AU. CONCRETE SHALL
BE 3000 P.S.I.
I
PLAN
~--
VULCAN FOUNDRY V-3827
RING a: GRATE OR APPROVED EQUAL
NO. .4 BARS AT 12• O.C.
BOTHWAYS
Fl = 275.10 (OUT)
NO • .4 BARS AT e• O.C.
IOTHWAYS
ELEVATION
JUNCTION BOX n.t.s.
.': :· ...... ·· . • .. .. ·" ;; •• ~-.: • • • .. ·.;: :· •• : •' ........ ·: 4 : .~ .. .
..... r···:··.··· .. : : ..
~. ~ ........ ··
-:· .. .
:i~ ~·1· .: -·
~·
....... . .
.: -.~. •"' .. ·.:.
1 (,2" DIA. BARS @
6' O.C. BOTH WAYS
1 /2" DIA. BARS 0
12" O.C. BOTH WAYS
DIA.
· .. :•.= .•· .... :. : ..• · .. ··; :.:'!' ·.·:
BrS AT r2" O.C BOTH rAY
PLAN VIEW
~· .. ~.
STD. CAST IRON MANHOLE
OVER & FRAME (24" DIA.)
1 /2" DIA. BARS 0 ·
12" O.C. BOTH WAYS
PROFILE VIEW
STANDARD CURB INLET
(NTS)
Water, Wastewater, Electric, Gas , Drainage and Traffic
Impact Analysis
ROBERT STEVENSON TRACT
29 .0 Acres
Prepared for:
TAC/KOVAK& COMPANY
Prepared by:
Municipal Development Group
203 Holleman Drive East
College Station, Texas 77840
SEPTEMBER, 1994
MDG PROJECT NUMBER: 2527
FILE NUMBER: 000631
TABLE OF CONTENTS
I. IN"TRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
II. EXISTIN"G CONDITIONS ............. · ....................... 2
III. ASSESSMENT OF IMPACTS .................................. 4
N. CONCLUSIONS ............................................ 6
LIST OF FIGURES
FIGURE 1: VICINITY MAP ........................................ 8
FIGURE 2 : DRAINAGE CALCULATIONS -1.50 ACRE TRACT .......... 9
FIGURE 3: DRAINAGE CALCULATIONS -27.58 ACRE TRACT ........ 10
I. INTRODUCTION
As various parts of College Station are developed it is important to examine the impact on
the existing water, wastewater, electric, gas, dr~ge and traffic systems. The new development will
increase the demand placed on the existing infrastructure. By determining the extent of impact caused
by a proposed project the possible stresses can be identified and more intelligently managed.
This study examines the impact of the maximum potential development of a 29.0 acre tract
on West Highway 6 between Rock Prairie Road and Birmingham (Figure 1 ). Current development
will be restricted to 1.50 acres, which will be developed under C-2 commercial zoning. The
remaining 27.58 acres, zoned C-2, will be reserved for future commercial improvement.
1
1.5 ACRE SITE
II. EXISTING CONDITIONS
Site: There currently exists an open field in its natural state. The 1.5 acre tract and the 27.58 acre
tract are both undeveloped. Humana Hospital exists on the adjoining tract to the west.
Water: The 1.50 acre portion of the study site is bounded by the west right-of-way line of Highway
6 and the south right-of:way ofRock Prairie Road. A 24" D .I.P. water main runs within the
Highway 6 right-of-way of Rock Prairie Road approximately 5.0 feet behind the curb and
within the Rock Prairie right-of-way approximately 7 .0 feet behind the curb.
Wastewater: A manhole exists approximately 60 feet from the southeast comer of the tract. An
additional 651£ of 6" sanitary sewer line is proposed. This line is located 16 feet behind the
curb and 5 feet in from the northeast property line for accessibility to the site.
Electric: There currently exists an overhead electric line traveling along the northeast property line.
This line is located 2 feet outside the northeast property line and 9 feet behind the curb .
Gas: A 6 inch intermediate pressure (35 PSig per Lone Star Gas) gas main currently exists on the
southwest side of Rio Grande Boulevard and on the northwest side of Rock Prairie Road.
2
i/u(rf
Pk ~ ~ ~ lfl.L ah11.i ~ --r1-4. J:fi~ ,~.
;f,(M/-of r.J: fJ'-"7",u.,( 9>L k~')_ ;~/ ~.
~ .V.£. -tR..-t.~ '.)_ t~-Ms i£-1 skJ./ ~ ~ 4' ~ rr ,1.,
f. wW-1""'" tt,., ~}h~ h..4?), c~.:h~ ? fft; c,,,._ k -¥h>-J ~'f An~ 4 /,tAsl fk42-' -~ott~~5". ~ ~ ~ ~:t{i..,, ~l,4--,
~~ ~ ~h~. /,
?. ut..,._f Jh-f,,__{J h4L wr'tl ~ ~ £r ~ 01 <LU..c.-
<l.u-e ( cr----1-., -"-~sU4//7 tefn'$/ c~_re-. --
>-. /f,,..; w,'(( Jl"i f./R-,_ tl«.<rs-ri2. ,._j.e . /<./>1 ~--/
;1~ ~,._,r-c .
l. a;~-1-~/ ~. ~1J o.-/ KP :' w. r~ ? w/11 ./&j
----A).J._ ,'!.,~ ~'-/={)-lf.JL~S"St'/-/.. (!XL ?
Drainage: The site drains in a sheet fashion in a southeasterly direction off the 1.5 acre tract toward
Birmingham. The entire site is currently grasslands and therefore relatively permeable .
Traffic: This site is currently seived by two public streets, which are Highway 6 Frontage Road and
Rock Prairie Road. Rock Prairie Road is a 4 lane urban minor arterial with continuous left
tum lane. It is 56 feet back of curb to back of curb street along the northwest side of the site.
3
IIl. ASSESSMENT OF IMPACTS
General: This entire 24 acre tract is zoned C-2 with no specific proposed development. Possible
future development may be similar to Furrow's. For the purpose of this impact study, the 1.5
acre tract is the focus of attention.
Water: The site is currently well served by public water. As depicted, a water line tied to the
existing 24 inch diameter water line will be utilized to provide domestic water, any necessary
irrigation water, and fire suppression.
A reasonable projection of the usages required for a C-2 site of this size is 7680
gallons per day, with a projected peak of38,400 gallons per day.
The substantial available water services appear to be adequate to meet any projected
demands.
Wasff\ This 1.50 acre site will be served by a proposed 6 inch line to be tied to the existing
~anitary sewer line. The existing line appears well-graded and in good condition.
There is a projected sanitary sewer load of 1680 gallons per day, with a peak loading of 8400
gpd. This is expected to cause no problem.
4
Drainage: Using the rational formula and a ten minute time of concentration the runoff of various
storms and are shown for the 1.50 acre tract and the entire 29.0 acre tract on Figure 2 and
Figure 3, respectively.
Traffic: Rock Prairie Road is a 4 lane minor arterial. The ultimate capacity of this street is 1,375
µ
vehicles per hour per lane or a total ~6-Cf\7ehicles per hour. That traffic volume makes
/lV
the daily capac~cles. A traffic count taken in the fall of 1991 estimates the
~o / I
daily usage at 6, 700 vehicle ~ of the ultimate capacity. Wt.. ~ ~ Y>o-t-enu./s.
The traffic capacity of the Texas 6 Frontage Road was calculated as 36 ,000 vpd.
Based on the most ~eme traffic inten siv e use within those allowed by C-2 zoning , projected
than adequate for these additional loads.
5
e available existing roadway capacities are more
Jt,,f ~ ~ t-1 auJLr t5Y
~"~1 ~~~ !. s--~
IV. CONCLUSIONS
Site: As a commercial development, the proposed Lot 1, TAC Realty Subdivision, when developed
will generate a substantial increase in tax revenue and utilities revenue while not significantly
burdening the overall infrastructure and services of the city.
Water: The proposed use of this tract generally will result in an insignificant increase in domestic
water use. Sufficient static pressures and residual pressures are obtained off of the same 24
inch line which services Humana Hospital and Southwood Athletic Park to the southwest.
Wastewater: There is an existing manhole 60 feet southeast of the comer of the subject tract which
joins an existing 6 inch diameter line that flows in a southeasterly direction toward
Birmingham. The existing sewer line will be extended to serve Lot 1, and will terminate in
a plug.
Electric: The developed lot must have electricity serviced underground as required by city
ordinance.
Gas: Natural gas service to the site should not be a problem It is available approximately 60 feet
offsite, across Rock Prairie, and is of sufficient pressure for any C-2 use . If the owner decides
6
gas is required the cost can be determined by Lone Star Gas. No further examination of gas
issues has been undertaken.
Drainage: Since any C-2 development of Lot 1 will produce a net increase in runoff: detention is
required by city ordinance. A sufficient storage volume will be created on site at the time the
site is developed and the site plan approval process is undertaken.
Traffic: ~emon ~d , the development of this site will not adversely affect the traffic system
w~L1 'J c:/RAM ~U I.
7
SITE ·
LOCATION
VICINITY MAP
NTS
Figure 1
DRAINAGE AREA -1.5 Acre Tract Rational Method (Q = CIA) Pre-Development Area Description (acres) .Q C(area) Grassland 1.50 0.40 0.600 Post-Development Area Description (acres) .Q C(area) Landscaping 0.00 0.40 0.000 Impervious Area 1.50 0.90 1.350 1.50 1.350 Cavg = 1.350 I 1.50 = 0.90 Runoff Req'd Storage Frequency Intensity* Cpre Cpost Qpre Qpost Vpre Vpost Volume (years) (in/in) ----(cfs) (cfs) .{.® .{.® _cg} 100 12.6 0.40 0.90 7.56 17.01 6804 15309 8505 50 11.1 0.40 0.90 6.66 14.99 5994 13487 7493 25 9.9 0.40 0.90 5.94 13.37 5346 12029 6683 10 8.6 0.40 0.90 5.16 11.61 4644 10449 5805 5 7.7 0.40 0.90 4.62 10.40 4158 9356 5198 *NOTE: Tc= 10 min
DRAINAGE AREA -29.0 Acre Tract
Rational Method (Q = CIA)
Pre -Development
Area
Description (acres} .Q C{area}
Grassland 29.00 0.40 11 .600
Post-Development
Area
Description (acres} .Q C(area}
Landscaping 27.50 0.40 11 .000
Impervious
Area 1.50 0 .90 1.350
29.00 12 .350
Cavg = 12.350 I 29.00 = 0.43
Runoff
Req'd Storage
Frequency Intensity* Cpre Cpost Qpre Qpost Vpre Vpost Volume
(years} (in/in} (cfs} (cfs} (£fl (£fl (£fl
100 12.6 0.40 0.43 146.16 155 .61 131544 140049 8505
50 11 .1 0.40 0.43 128 .76 137 .09 115884 123376 7493
25 9.9 0 .40 0.43 114.84 122 .27 103356 110039 6683
10 8 .6 0.40 0.43 . 99.76 106.21 89784 95589 5805
5 7.7 0 .40 0.43 89.32 95.10 80388 85586 5198
*NOTE : Tc= 10 min