HomeMy WebLinkAbout45 Remmington Subd. Lots 1 2 99-328 1605 Rock Prairie Rd.DEVELOPMENT PERMIT
PERMIT NO. 99-500328
College Station Professional Building Detention Pond
FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA
RE: CHAPTER 13 OF THE COLLEGE ST A TION CITY CODE
SITE LEGAL DESCRIPTION:
Remington Subdivision Lots 1 & 2
DATE OF ISSUE: 12/31/1999
OWNER:
Walt Schoenvogel
P.O. Box602
Brenham, TX 77834
(409) 836-5482
TYPE OF DEVELOPMENT:
SPECIAL CONDITIONS:
SITE ADDRESS:
1605 Rock Prairie Road
DRAINAGE BASIN:
Bee Creek Tributary A
VALID FOR 12 MONTHS
CONTRACTOR:
RE-GRADING OF THE DETENTION POND AREA ONLY
NIA
The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate
construction site in accordance with the approved erosion control plan as well as the City of College Station
Drainage Policy and Design Criteria. The Owner and/or Contractor shall assure that all disturbed areas are sodden
and establishment of vegetation occurs prior to removal of any silt fencing or hay bales used for temporary erosion
control. The Owner and/or Contractor shall also insure that any disturbed vegetation be returned to its original
condition, placement and state. The Owner and/or Contractor shall be responsible for any damage to adjacent
properties, city streets or infrastructure due to heavy machinery and/or equipment as well as erosion, siltation or
sedimentation resulting from the permitted work.
Any trees required to be protected by ordinance or as part of the landscape plan must be completely fenced before
any operations of this permit can begin.
In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to
insure that debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing
drainage facilities.
Date
Contractor Date
\~
FINAL DRAINAGE REPORT
FOR THE
COLLEGE STATION
PROFESSIONAL BUILDING I & II
DRAINAGE IMPROVEMENTS
COLLEGE STATION, BRAZOS COUNTY, TEXAS
DECEMBER, 1999
M u ICIPA L D EVELOPMENT G ROU P
2551 TEXAS AVE . SOUT H , STE . A
COL LEG E STATION, TEXAS 77840
Ph : (409) 69 3 -5359 Fx: (409) 6 9 3-4243
E -mai l: mdgcs@get.net
Consultin g En ginee rs · Surveyo rs
Planner s · Environment al Consult ant s
REV\EWED FOR
\ coMPLIAl\lCE.
oEC S 1 '999
C QL\..E.GE. S1A1\0N EN W \NG
TABLE OF CONTENTS
1.0 PRO.JECT SCOPE ...... .' .......... : ............. ·: ........... : ................. .' ..... :: ....................... .' .... 4 ..
I . I SITE LOCATION .................................................................................................... 4
' 4 . I .2 GENERAL DESCRIPTION · .. ···:·····v·····'"·.: ............... , ........................•. : ................... ·.. ·
2.0 DRAINAGE BASINS & SUB-BASINS .................... :··········.······························: .. : 5
2 .1 MAJOR DRAINAGE BASIN DESCRIPTIONS .................................. : ................... 5
2.2 SUB-DRAINAGE BASIN DESCRIPTIONS ........................................................... 5
3.0 DRAINAGE DESIGN CRITERIA & CONSTRAINTS ....................................... 6
3 .1 STREET DRAINAGE ............................................................................................. 7
3 .2 STORM SEWER INLETS ....................................................................................... 7
3.3 STORM SEWER SYTEMS ..................................................................................... 8
3 .4 OPENCHANNELS ................................................................................................. 8
3 .5 CULVERTS ............................................................................................................. 9
3.6 DETENTION FACILITIES ..................................................................................... 9
4.0 DRAINAGE SYSTEM MODELING .................................................................. IO
4 .1 STREET DRAINAGE ........................................................................................... IO
4 .2 STORM SEWER INLETS ..................................................................................... 10
4 .3 STORM SEWER SYSTEMS ................................................................................. 10
4 .4 OPEN CHANNELS ............................................................................................... 11
4 .5 CULVERTS ........................................................................................................... 11
4.6 DETENTION FACILITIES ................................................................................... 11
5.0 CONCLUDED DRAINAGE IMPROVEMENTS ............................................... 12
5.1 DETENTION FACILITIES ................................................................................... 12
APPENDIX A -HYDRAULIC COMPUTATIONS
APPENDIX B -MAPPING
APPENDIX C -REFERENCED DRAINAGE STUDIES
LIST OF TABLES
DESCRIPTION PAGE NO.
TABLE # 1 -Drainage Area 1-4 .................................................................................... 12
TABLE #2 -Design Sumary ......................................................................................... 13
TABLE #3 -Drainage Area 1-5 .................................................................................... 14
C.S . Professiona l Buildin g I & II
Drai nage improvem ents
1.0 PROJECT SCOPE
Muni ci pal Development Gro up
This report outlines the drainage improvements necessary to rehabilitate the
ex istin g detention facilit y located on Lot 1, Block One of the Remington
Subdi v ision . Also , the study provides for the necessary drainage calculations and
design improvements to provide additional detention for the proposed
development of the Professional Building Two on Lot 2 of the same subdivision.
The drainage report will address the requirements necessary for the above
improv ements in accordance with the provisions of the City of College Station
Drainage Policy and Design Standards.
1.1 SITE LOCATION
The project is located on the north side of Rock Prairie Road west of State
Highway 6 and directly across from the College Station Medical Center.
As mentioned before, the subjected properties are Lot 1 and 2 of Block
One of the Remington Subdivision . Surrounding existing developments
immediately adjacent to the project site are ; Southwood Terrace
Subdivision to the north, The Professional Building (One) to the west and
located on Lot 1, and Ponderosa Place Section Two to the east containing
the Econophone building .
1.2 GENERAL DESCRIPTION
The College Station Professional Building (One) is located on Lot 1 of the
Remington Subdi v ision. This subject property is significantl y developed
w ith a main structure, concrete parking areas and drives , and landscaped
parking islands. Located in the rear of the lot , at north boundary, is the
existing detention pond that was designed by Galindo Engineers and
Planners in 1990 . Their subsequent drainage report is attached in
Appendix C -Referenced Drainage Studies . For clarity this detention
pond wi ll be referred to as the Lot 1 Detention Pond in all other reference s
of the report .
000736-3258 Dra in age Report .doc Final Drainage Report -4
C.S . Professional Building I & II
Drainage Improvem ents Muni cipal Developm ent Group
Lot 2 of the Remington subdivision is currently vacant but is planned to
contain the Professional Building Two . This land generally slopes to the
northwest to the Lot 1 Detention Pond at a grade of approximately 2 .50%.
This site is currently unimproved with native grasses and weeds . Located
at the rear of this lot, the north boundary, is another detention pond that
was designed by Esmond Engineering, Inc . in 1995 . This pond is both
located on Lot 2 of Remington Subdivision and Lot B 1 of Ponderosa
Place, Section Two. Their subsequent drainage report is attached in
Appendix C -Referenced Drainage Studies . For clarity this detention
pond will be refereed to as the Lot 2 Detention Pond in all other references
of the report .
2.0 DRAINAGE BASINS & SUB-BASINS
2 .1 MAJOR DRAINAGE BASIN DESCRIPTIONS
The drainage improvements project site is contained within the drainage-
watershed of the Carter 's Creek Drainage Basin . This drainage basin is
illustrated on Exhibit #I -"Carter 's Creek Drainage Basin" located in
Appendix B -Mapping. The borders of this drainage basin roughly
consist of Rock Prairie Road on the south and west, State Hwy No 30 to
the east, and State Hwy No . 21 to the north .
2 .2 SUB-DRAINAGE BASIN DESCRIPTIONS
The Lot 2 Detention Pond was designed to have a storage volume of
approximatel y 47 ,800 ft 3 with a ma x imum discharge rate of 15 .11 cfs
during the I 00-year rainfall event. The subject detention pond receives
almost 100% of the runoff from Lots BI , B2, G 1, & G2 of Ponderosa
Place, Section Two . The remained runoff drains into the street gutter of
Rock Prairie Road and Longmire Drive and has no bearing on the Lot 2
Detention Pond or the Lot 1 Detention Pond . The discharge of this pond
is metered by an 18 " 0 pipe and routed into the Lot I Detention pond . For
calculation purposes the information gathered from the Esmond report will
000736-3 258 Drainage Repo11 .doc Fina l Drainage Report -5
C.S . Professiona l Building I & II
Drainage Improvem ent s Muni cip a l D evelopm ent Group
be assumed corrected and storage calculations will be based from the
15 .11-cfs maximum discharge value .
Immediately downstream is the Lot 1 Detention Pond . The pond was
designed to have an approximate storage volume of 27 ,575 ft3 with a
maximum discharge of 13 .11 cfs during the 100-year rainfall event. The
subject detention pond receives almost all of the runoff from the 7 .02
acres of Lot 1 and 2, in addition to the discharge of the Lot 2 Detention
Pond being the pre-development runoff rate of its receiving watershed .
The discharge of the Lot 1 Detention Pond is metered out through an 18 "
0 orifice, into a 4 ' wide drainage ditch and onto the surface of Long Leaf
Circle . Thence, the runoff is directed by residential streets to Tributary
"A" of Bee Creek, being a sub-drainage basin to the Carter 's Creek
Drainage Basin . This sub-drainage basin is illustrated on Exhibit #2 -
"Carter 's Creek Drainage Basin -Partial " located in Appendix B -
Mapping . The projects drainage basin for the Lot 1 Detention Pond is
illustrated on Exhibit #3 -"Lot 1 Detention Pond Drainage Area" located
in Appendix B -Mapping .
The project site is not located within the 100-year floodplain as shown on
the Flood Insurance Rate Map , (FIRM) Map No . 48041 C0205 C havin g
an effective date of Jul y 2 , 1992. An excerpt of the FIRM map with the
location of the project site is illustrated on Exhibit #4 -"FIRM Map "
located in Appendix B -Mapping
3.0 DRAINAGE DESIGN CRITERIA & CONSTRAINTS
For all de ve lopment within the City of College Station, there are criteria on the
use of w hich desi g n storms and development conditions for type of drainage
improve ments . Below, in each type of improvement , the required desi gn
constraints are more fully detailed . All drainage improvements shall also be
000736-3258 Drainage Report .d oc Fina l Dra in age Re port -6
C.S . Profess iona l Bu ildin g I & JI
Drai nage Imp rovem ent s Muni cip a l D evelopm ent Group
analyzed during the 100-year rainfall event to insure that no adverse conditions
will ex ist.
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.
•:• Maximum velocity not to exceed 10 ft/sec and mm1mum 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 :
)P.-Arterial & Parkway-One clear lane in each direction 24 foot total
clearance at center of street.
)P.-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,
w hichever 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 follo w in g constraints shall dictate the design of all storm sewer inlets :
•:• Inlet s on all streets , except for residential , shall be recessed with a
minimum 4" depression .
•:• Curb opening s shall be a minimum length of 5 feet.
•:• Inlet s with greater than a 5" gutter depression on streets with less than
a 1.00 % grade shall be designed in sump conditions .
•:• Inl et s at brid g es and culvert structures shall be oversized to
accommodate 125 % of the 10-year rainfall e v ent.
•:• Ponding at curb inlets shall not exceed 18 " in depth.
00 0 73 6 -3258 Drainage Rep0tt.doc Fina l Drainage Re po rt -7
I
C.S. Profess ional Building l & II
Drainage Improvement s Muni ci pal D evelopm ent Group
3 .3 STORM SEWER SYSTEMS
3.4
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 .
•!• 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 Jess 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 wi dth 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.
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.
000 736-3 258 Dra inage Report .doc Fina l Drainage Report - 8
C.S. Professiona l Building I & II
Drain age improvem ents Municipal D evelopm ent Gro up
•!• 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.
3.5 CULVERTS
Culverts 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 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-y ear 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 :
);;>-Natural channel or seeded cover at 6 .0 ft /s ec .
)..-Sodded cover at 8 .0 ft /sec.
Y 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-v egetative cover.
000736-3258 Drain ag~ R epor1.doc Fin a l Drainage Report -9
I
I
C.S . Pro fess io na l Bui lding I & II
Drainage Imp rove m ent s Muni cipal De velopm ent Group
4.0
)
•:• Bottom slopes of the detention basin with vegetative cover shall be at a
grade of 20 : 1 with low-flow pilot channels .
•:• Minimum of0.5 feet offreeboard 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 .
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 frequency ,
and "A" is the drainage area in acres. A minimum 10-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
p rogram, 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
Win Storm v . 1.3 . Within this program, basic geometry and characteristics
000 73 6-3 25 8 Drain age Repo rt .doc Fin a l Dra ina ge Report -I 0
C.S . Profess iona l Building I & II
Dra in age Improvem ent s Muni cipa l D ev elopment Gro up
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 box es , 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
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 CUL VER TS
Culverts are evaluated one of two ways :
Short , singular culverts are calculated with the Texas Department of
Tran sportation (TxDOT) hydraulic program Culverts v . 1.0 . Within this
program, basic g eometry and characteristics of a culvert can be defined .
This would included data such as tailwater, geometry, and entrance/ex it
losses . For each culvert investigations will be made in order to determine
w hether it is inlet or outlet controlled .
For lon g er more complex culvert with bends and grade transitions the
pro gram StormCad v. 1.0 by Haestad Methods will be used .
4 .6 DETENTION
D etention requirements are determined by graphical means. Tabulations of
the pre-dev elopment and the post-development hydrographs of the
drainag e areas are pro v ided. The hydrographs are based on the standard
000736-3258 Drainage Repo rt .doc Fina l Drai nage Report -11
I
C .S . Professiona l Buildin g I & II
Dra in age Impro vem ents Muni cipa l Development Group
5.0
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.
CONCLUDED DRAINAGE IMPROVEMENTS
The proposed improvements to the Lot 1 Detention Pond are described as follows .
These improvements provided for the rehabilitation of the existing pond , to detain
the existing runoff from the Professional Building One, and the projected runoff
of Lot 2 with the development of the Professional Building Two.
5 .1 DETENTION FACILITIES
Since all drainage systems will remain constant except for the proposed
development on Lot 2 all other previous calculations will be used for the
new pond sizing . Per the Galindo report, drainage areas 1-1 , 2 , 4 , 6 & 7 /J J ~ '. drain to the Lot I Detention Pond, (see Exhibit #6 of the Galindo Report).
t/f Drainage areas 1-3 & 5 drain to the gutter of Rock Prairie Road . At the
· e of that study the required detention volume calculated was at 27 ,535
ft3 . The proposed development of Lot 2 wil ncrease ermeability of
Galindo 's drainage areas 1-4 and 1-5 . Therefore, this increase runoff will
be added to the original detention pond volume to obtain a new pond
v olume. The calculated drainage values for these drainage areas are
summarized as follows :
Drainage Area 1-4
TABLE #1 -DRAINAGE AREA (1-4)
2 N/A 13 .808
5 3.700 16 .790
10 4 .200 18.845
25 4.800 21 .523
50 5.500 24 .330
100 5.700 24.403
000736-3 25 8 Dramage Repo rt .doc
N/A
13 .090
14 .645
16 .723
18 .830
18 .703
Fi na l Drainage Re port - I 2
C .S . Professiona l Bu ilding I & II
Drain ag e Improvem ent s Muni cipa l D evelopment Group
The original configuration of Galindo ' s drainage area 1-4 will be modified
as shown on Exhibit #3 -"Lot 1 Detention Pond Drainage Area".
Therefore the original drainage area of 1. 7 acres will increase to a size of
2.43 acres taken in a portion of drainage area 1-5 . As shown in Table #1
this increase in drainage runoff will require an additional detention pond
v olume of 17 , 733 ft:3, bringing the total volume of the Lot 1 Detention
Pond up to approximately 45 ,308 ft 3 (27 ,575 + 17 ,733). This volume
increase will still allow the pond to function properly and allow a
maximum discharge rate of 13 .11 cfs at the original pre-development
runoff rates . Also , there will be a concrete pilot channel constructed from
the Lot 2 Detention Pond to the Lot 1 Detention Pond sized for 1/3 of the
5-year rainfall event. Below in Table #2 is a summary of the design for
the Lot 1 Detention Pond:
TABLE #2 -DESIGN SUMMARY
?? :::] :tQQNP1TJ.PN tr '@: :M.$.UQJ:it JPNi!Tti
DETENTION POND
~~~~~~~~~--1
ft3 Required Detention Volume
10% Sedimentation Increase
Total Required Detention Vol
Provided Detention Volume
PILOT CHANNEL
45308
4531
49839
41658
ft3
ft3
ft3
~~~~~~~~~--1
(1/3) 5-Year Rainfall Event 1.233
Required Top Width 2.68
Provided To Width 3
cfs
ft
ft
The Lot 1 Detention Pond final design volume will have a total detention
capability of 41 ,658 ft 3 , which is less 6, 181 ft 3 of the required amount.
The shortfall will be detained in the future concrete parking lot of Lot 2
and metered out at rates no greater than the pre-development flows located
in Table #1. At the time of site development grades , areas and a
supplemental drainage letter will be provided for showing how this 6, 181-
ft3 detention volume is meet.
00073 6 -32 58 Drain age Rep ort .d oc Fina l Drainage Report -13
C.S . Professiona l Bu il din g I & II
Drain age Improvem ent s Muni cipa l D evelopm ent Grou p
Drainage Area 1-5
TABLE #3 -DRAINAGE AREA (1-5)
: := ~!Nntmlf ' '''0 SVSLO:RM5N1?RUN QRE :
::::::i 1~~1~11 l l\!l \ii\ ~,, ;;::::r::i; i!\!li~ 1111:
2 N/A 2 .089 N/A
5 2.400 2 .540 0.140
10 2.700 2 .851 0.151
25 3.100 3.257 0.157
50 3.600 3.681 0.081
100 3.700 3.844 0.144
Galindo 's drainag e area 1-5 will actuall y be decreased in size from 1.1
acre s to 0 .3 7 acres . Though there w ill be a significant amount of
dev elopment and imperviou s cover the reduction of drainage area will
create a near matchin g pre and post-development runoff rates. Therefore,
no detention will be required for the runoff of thi s drainage basin . This is
illustrated in Table #2 abo ve .
000 73 6-32 58 Dra in a ge Re port .doc Fin a l Dra inage Re port -14
000736-3258 Drainage Report.doc
APPENDIX A
HYDRAULIC COMPUTATION
1 :._ 6
...
" . ' <.1;.· ,·
I
I
DESCRIPTION
APPENDIX A
TABLE OF CONTENTS
PAGE NO.
Drainag e Area 1-5 (Runoff Calculations & H ydrographs) ........................................... A-1
Drainag e Area 1-4 (Runoff Calculations & H ydrograph s) ........................................... A-2
Low Flow Pilot Channel .............................................................................................. A-3
000736-3258 Drainage Re port .doc
I
I
POST-DEVELOPMENT
GENERAL INFORMATION
Description : Dra inage area of site after development
Drainage Area (A 1) = 2 .070 acres (impervious area)
Drainage Area (A 2) = 0 .360 acres (landscaped area)
TIME OF CONCENTRATION (TJ
GIVEN
Maximum Travel Distance (D 1) =
Velocity of Runoff (V1) =
Coefficient of Runoff (C 1) =
Maximum Travel Distance (D 2) =
Velocity of Runoff (V 2) =
Coefficient of Runoff (C 2) =
460 ft
ft 3 .10 /sec
0.95
160 ft
ft 1 .00 lse c
0.55
-NOTE: Minimum Tc allowed= 10 min.
2 YEAR FREQUENCY. RATE OF DISCHARGE (Q)
Coefficient (e) =
Coefficient (b) =
Coefficient (d) =
0 .806
65
8
5 YEAR FREQUENCY. RATE OF DISCHARGE (Q)
Coefficient (e) = 0 .785
Coefficient (b) =
Coefficient (d) =
76
8 .5
10 YEAR FREQUENCY. RATE OF DISCHARGE (Q)
Coefficient (e) =
Coefficient (b) =
Coefficient (d) =
0.763
80
8.5
25 YEAR FREQUENCY. RATE OF DISCHARGE (Q)
Coefficient (e) = 0 .754
Coefficient (b) = 89
Coefficient (d) = 8 .5
50 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0 .745
Coefficient (b) = 98
Coefficient (d ) = 8 .5
100 YEAR FREQUENCY. RATE OF DISCHARGE (Q)
Coefficient (e ) = 0 .73
Coefficient (b) =
Coefficient (d ) =
000736-3258 Drainage Calculati ons. Bas in 1-4.xls
96
8
RESULT
Tc1 = 2 .5 min .
TC2 = 2 .7 min .
Tc(POST) = 5 .1 min .
Rainfall Intensity (1 2) = 6 .327 in/hr
QAREA 1 = 12.545 cfs
QAREA 2 = 1 .263 cfs
·=·=·=·=·=·=·=·=·=·=·=·=·=·=·= .,.,,,,,,,,,,,,,,,,,,,,,,,,,,,,, ·=·=·=·=·=·=·=-=·=·=·=·=·=·=·=·=·=·=·=·=·=·=·=·=·=== .•.••.••.•_,.._=_•·.~_·=.•·.•~=.o·=·:·=.a·=·=_·•.••.••-~.=··=.·•.===•. •rt• •Bi:~M • ••@••• : ::::•>t •••••t /Mt~,.-.,.·.·.·~,.~
Rainfall Intensity (Is) =
QAREA 1 =
QAREA 2 =
7 .693 i%r
15 .254 cfs
1.536 cfs
• . .= . .=.~.--_.· .. _ .. :_ •. _._.·.·.•=.'.'.'_, .... _;,,,_;_•_,' .. '.,'.J_.=_.:_,=_.:_,=_.:_,=_ •. •.•.·.•=.•.•.••.•.·.•.•.•.•.:•.:_•.:_•.:.•.:•_·:_•_:.•.·.•.•.:_:. :: , : :•: :?1:6179.b bf$ ]I ·:-:-:-··:-:·:·:-:·:···:···:···:-:-:-:-:-:·:····-:-:-:-:-:-:-:-:-:-:·:·
Rainfall Intensity (1 10) =
QAREA 1 =
in/ 8 .635 hr
17 .121 cfs
Q ARE A 2 = 1 . 724 cfs
•_1,."'.=',.· .. •,· .. •,·_.',?='_.•,.·.·.•~•.=.·.•.•,J_,._,:.._•',.'.,',.=.,=,:_:_• .. =_,•_:.·_••,.=.••,•=.•,·.=•.•= . .:_,•.•_,·.•·_,•.• ... =•.••,.•.•_,•_,•_,· .• •_, •_l_J_,•_;_,•_J_, •_J_.:_,•.:_•• . .:_,·_:•_J_.:_;_.:_J_.:_,• . .:_;_.:_;_.:_;_.:_, ........... tt1i.illil5•crs •_,:•.:•.:•_,_••_, ~ ·:::::::::::::::::::::::::·::::::::::::::::::::::::::::::::::.;.;.;.;.·.;.;.;.;
Rainfall Intensity (1 2s) = 9 .861 in /hr
QARE A 1 = 19 .554 cfs
QARE A 2 = 1 . 969 cfs
s~••ai.=· •:. :::]••·• •:: • •••• ::·•·~1 ~!1i••~=·::
Rainfall Intensity (Isa) = 11 .148 in /hr
QAREA 1 = 22 .105 cfs
QAREA 2 = 2 .226 cfs
·.:• . .n_,' .. '_.· .. • .. · .. = .. =.•_c:c••.••.•.•_:=•.• . .:_.=.=.== .. •_,' .. '_,'.. .=.••.·.•• .•. •.·.••.=.••.·.•.••.·•.: •. ••.:•.•.•=.•.•.••.•.:.••.:_ •.•.•.•.•.•.•.•. ·.•.=.•.:.• .•.•.•.•.•.••..•.•. •.:.•·.•.•.:·.•.•.•.•.•.:.•.•-•.·.•.•.•.:.•.•.•.•.•.•.•.•.•.•.·.'.· ::: • iiJi.3.0.•: ¢{$ 1 i ~ -:-:-:-:-:-:·:-:-:·:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:-:·:··-·.·.·
Rainfall Intensity (11 0 0)
QAREA 1 =
in / 11 .639 hr
23.079 cfs
QAREA 2 = 2.324 cfs
•.§ii•§· :•.• : ::::•,: ••••••• ••• 0: ·•••·· gl i!g~ i~ ]
HYDROGRAPHS Chart 5
5-YEAR HYDROGRAPH
16 ------------
Volume Co
~ 10
Co-'
~ -< ~ = ~ u -'JJ ..... 8 ~
6
2
0 10
fJ Post-D eve lopm ent El Pre-Development
HYDROGRAPHS Chart 5
TIME
(min)
20 30
HYDROGRAPHS Chart 6
10-YEAR HYDROGRAPH
20----------------------..-------------------....,..--------------------~
12
~
~
~ -~ ,:; 10 c.J u -rJ:J ....
Q
8
0 10
Iii Po st-D eve lopm ent D Pre-Development
HYDROGRAPHS Chart 6
TIME
(min)
20 30
I
I
HYDROGRAPHS Chart 7
25-YEAR HYDROGRAPH
Volume Convey
15
~
~
~ -~ c.:
c.I u -00 ....
Q
10
0 10
E1 Post-Development D Pre-Development
HYDROGRAPHS Chart 7
TIME
(min)
20 30
I
HYDROGRAPHS Chart 8
50-YEAR HYDROGRAPH
30
Volume Conveyed
20
-..:; 15 CJ -
10
5
0 10
8Post-Deve lopm ent D Pre-Development
HY DROGRAPHS Chart 8
16,947 ft:3
TIME
(min)
20 30
I HYDROGRAPBS Chart 9
100-YEAR HYDROGRAPH
35----------------------------------.----------------------------------.---------------------------------.
Volume Conveyed 17,733 ft:3
20
~
~ c:::
~ -~ = CJ u -rJ:J -Q
15
0 10
DPre-Dev elopmen t [J Pos t-Development TIME
(min)
HYDROGRAPHS Chart 9
20 30
I
I
I
I
I
POST-DEVELOPMEN T
GENERAL INFORMATION
Description: Drainage area of site after development
Drainage Area (A 1) = 0 .310 acres (impervious area)
Drainage Area (A2) = 0 .060 acres (landscaped area)
TIME OF CONCENTRATION CTc)
GIVEN
Maximum Travel D istance (D 1) =
Velocity of Runoff (V1) =
Coefficient of Runoff (C 1) =
Maximum Travel Distance (D2) =
Velocity of Runoff (V2) =
Coeffic i ent of Runoff (C 2) =
460 ft
ft 3 .10 f sec
0 .95
160 ft
ft 1 .00 fsec
0.55
-NOTE : Minimum T c allowed= 10 min .
2 YEAR FREQUENCY. RATE OF DISCHARGE (Q)
Coefficient (e) =
Coeffici ent (b) =
Coefficient (d) =
0 .806
65
8
5 YEAR FREQUENCY, RATE OF DISCHARGE (Q)
Coefficient (e) = 0 .785
Coefficient (b) =
Coefficient (d) =
76
8 .5
10 YEAR FREQUENCY. RATE OF DISCHARGE (Q)
Coefficient (e) = 0.763
Coefficient (b) =
Coefficient (d) =
80
8.5
25 YEAR FREQUENCY , RATE OF DISCHARGE (Q)
Coeffi c i ent (e) =
Coefficient (b) =
Coeffi c ient (d ) =
0 .754
89
8 .5
RESULT
T c1 =
T c2 =
T C(POST) =
Rainfall Intensity (1 2) =
Q ARE A 1 =
Q AREA2 =
2 .5 min .
2 .7 min .
5 .1 min .
6 .327 in/hr
1 .879 cfs
0 .211 cfs
::11•a:]: • ··:.:::: •, ::::::::::::: : :: ; :,, , ,,,,,, •:•r•••·1~1.11 : 1.$.:r::
Rainfall Intensity (1 5) = 7 .693 in/hr
QA REA 1 = 2 .284 cfs
Q ARE A 2 = 0 .256 cfs
m·.5_·::-.. •::::: •O::,,.:'•.·]':·:·: ·: .·:::-.•:1~11 -Pt~ii •
Rainfall Intensity (1 10) = 8 .635 in/hr
Q AREA 1 = 2 .564 cfs
Q ARE A 2 = 0 .287 cfs
m1•;n; ::: ::: : "'\ :': :: ',·'.·',·',·',·',·',·',,',·',,,'·'.·',·'.·',·'.·',·'.·',·'.·',·'.·',·'.· .. •_,•,.:_•·.•_.'_:_:_.•.•• .. ·.•• ... _,., .. _,'.·'.,._·'_,.,·'.,' .... =.' .... •.•.'.=.•.-.•• .. ••. :2J1s.1 :ijti. : :\:-:,::. ,...\::: :::::::::;::::::::::: :{{:{ ................ ·.;.·.;.;.;.;.;.;.;.· ........... · ... .
Rainfall Intensity (1 25 ) = 9 .861 in /hr
Q AREA 1 = 2 .928 cfs
Q AREA 2 = 0 .328 cfs
·········· ·················· ·.·.·.·.·.· .. ·.·.·.·····:················· .. · .. ·.·.·.·.·.·.·.· .. ·.·. ·•·•· ...
•.·=,a .. ·,.·_ •. .-,.·,:;__.•·.·•'.·=· ...... _='.t,~.-'.:_:,.·.:,.·.•',=·.=',=·.t,=·.•',=".••.·.•'.= ' ::r •••••=••==::: = , ..... t :r:r.a_:_~l.$. 1_._,•.••.•=.¢tS.:.: ... :.•.•.•=.· =.'.•:.:•.••_:::.· :.49. ·:::::;:::::::;:::::;:;:;:::::::::;:;:;:;:;:::;:;:;:::::::·.·.··.
50 YEAR FREQUENCY , RATE OF DISCHARGE (Q) Rainfall Intensity (1 50) = in / 11.148 hr
Coeffici ent (e ) = 0 .745 Q AREA 1 = 3 .310 cfs
Coeffi c i ent (b) =
Coeffi c i ent (d ) =
98
8 .5
QA REA 2 = 0.371 cfs
::a ·a·•···= • •• •• :•:. : :::• a.~u.1.:it~H . ::
100 YEAR FREQUENCY. RATE OF DISCHARGE (Q) Rainfall Intensity (1 100) in/ 11.639 hr
Coeffici en t (e) = 0 .73 QA REA1 = 3 .456 cfs
Coeffi c i ent (b) =
Coe ffi cient (d ) =
000736-3 258 Drainage Calcu lations. !Jas in 1-5 .xls
96
8
Q AREA 2 = 0 .387 cfs
•.:.m.:_:_·· __ )l _r.._=_=•.••.•~-·.:::.•.•'.••.••.••.•• ...... ••.•·.••·.=••.•·.••.••.••.'.'.••.••.•.••. •• = • s:~e.44. d'si ·•:: :~~ :-:-;.:.:-:-:-:-:-:-:-:-;.;.:-:-:-:-:-:-:-:-;.:-;.:-:-:-·-:-:-:-:-:-:-:-;.:-.·.·.·.·.·.·.·.·.·.·.·.·.·.····
I
I
HYDROGRAPHS Chart 5
5-YEAR HYDROGRAPH
0 10
El Po st -D evel opm ent []P re -Development TIME
(min)
HY DRO GRAP HS Chart 5
20 30
I
HYDROGRAPHS Chart 6
10-YEAR HYDROGRAPH
3
Volume Conv
-"5 1 .5 -t--------fl::;;:;:=::;:::;::;:;; -
1
0 .5
0 10 20
I El Post-D ev elopm ent 0 Pre-Development I TIME
(min)
I-I YDRO GRAP HS Chart 6
30
HYDROGRAPHS Chart 7
25-YEAR HYDROGRAPH
2
~
~
~ -~ ~
~ u -00 ....
~ 1.5
0 10 20
Im Post-D ev elopm ent 0 Pr e-Development I TIME
(min)
HYDROGRAPHS Chart 7
30
I
I
HYDROGRAPHS Chart 8
50-YEAR HYDROGRAPH
4
Volume Conveyed
2.5
~
~ ~ -~ c:: 2 v u -r.ri .....
~
1 .5
0 10
El Post-Development El Pre-Development
HYDROGRAPHS Chart 8
73 ft 3
TIME
(min)
20 30
I
I
I
HYDROGRAPHS Chart 9
100-YEAR HYDROGRAPH
Volmne Conveyed 129 ft3
5,,._ ________ --j
0 10
[J Pre-Development D P os t-Development
HY DROGRAPHS Chart 9
TIME
(min)
20 30
I
I
12107/99
Project Description
Project File
Worksheet
Flow Element
Method
Solve For
Input Data
Mannings Coefficient
Channel Slope
Left Side Slope
Right Side Slope
Discharge
Results
Depth
Flow Area
Wetted Perimeter
Top Width
Critical Depth
Critical Slope
Velocity
Velocity Head
Specific Energy
Froude Number
Flow is supercritical.
Worksheet
Worksheet for Triangular Channel
i:\projects\700\3258-professional bldg 2 , drainage study\3258t1 ra.fm2
Low Flow Pilot Channel (1/3 the 5 yr)
Triangular Channel
Manning's Formula
Channel Depth
0 .013
0 .65 %
4 H :V
4 H :V
1.233 cfs
0.34 ft
0.45 ft2
2 .76 ft
2 .68 ft
0.36 ft
0.004549 ft/ft
2 .74 ft/s
0.12 ft
0.45 ft
1.18
Municipal Development Group
01 :55 :50 PM Haestad M eth ods , Inc . 37 Brook side R oad W aterbury, CT 0 6708 (203) 755-1 666
Fl owMas t e r v5 .0 7
Page 1of1
000736-3258 Drain age Report .d oc
APPENDIXB
MAPPING
..
,·
·.
' .
• f
"
I
I
I
I
I
DESCRIPTION
APPENDIXB
TABLE OF CONTENTS
PAGE NO.
Exhibit #1 -Carter 's Creek Drainage Basin ................................................................ B-1
Exhibit #2 -Carter's Creek Drainage Basin -Partial ................................................... B-2
Exhibit #3 -Lot 1 Detention Pond Drainage Area ....................................................... B-3
Exhibit #4 -FIRM Map .............................................................................................. B-4
000736 -3258 Drain age Repo rt .d oc
Brazos County
Unincorpo r ated Areas
481195
ZONE X
'
......___.._.., . /)
City of College Station ~
480083
(
'
(( ,,
'\\ ,~_
.. ··
APPENDIXC
REFERENCED DRAINAGE STUDIES
000736 -3258 Drai nage Repo rt .doc
DESCRIPTION
APPENDIXC
TABLE OF CONTENTS
PAGE NO.
Esmond Engineering, Inc. -Drainage Study (1995) .................................................... C-1
Galindo Engineers and Planners -Drainage Study (1990) ........................................... C-2
000736-3258 Drain age Rep m1 .d oc
ESMOND ENGINEERING. INC.
Environmental Consultants ~21
CRYSTAL PARK PLAZA• 2700 EAST BYPASS• SUITE 4600 •COLLEGE STATION, TEXAS 77845 --~ • OFFICE (409) 764-7640 • WATS (800) 444-7640 • FAX (409) 693~729
February 22, 1995
Attn: Veronica Morgan , P .E.
Assistant City Engineer
City of College Station
P.O . Box 9960
College Station, TX 77842
Re: Site Development/Site Drainage for Longmire Self Storage, Tract B, Ponderosa Place ,
Section Two, College Station, Texas
Dear Ms. Morgan:
Enclosed is our revised drainage report for the above referenced tract. We have attempted to
incorporate your review comments by adding a section at the end which deals with the adjacent
parcel known as Tract D. A revised drawing also accompanies this report, which further
incorporates your review comments.
Please contact myself or Lee Adams if you have any questions or need any additional
information.
Very truly yours ,
~~;:::rtG , INC.
Steven E. Esmond , P.E.
President
SEE/pa
c: Larry Klotz
l 3 08 /CS-07. L TR
Introduction
Drainage Report
for
Tract B, Ponderosa P lace, Section 2, Vol 669, Page 651
College Station, Texas
prepared by
Esmond Engineering, Inc.
A hydrologic analysis was performed on Tract B, Ponderosa Place, Section 2, Vol 669, Page
651, ·college Station, Texas, consisting of 6 .024 acres. This drainage report has been prepared
in accordance with current City drainage design standards.
A drainage map accompanying this report illustrates the configuration and topography of the site.
The owner is proposing to develop the property as a commercial storage facility which would
consist of buildings and pavement covering most of the land. The site sits on some of the
highest ground in the City. Near the center of the site is a high point from which the natural
drainage flows downhill in virtually every direction. Longmire Street, which borders the
northeast boundary, receives about 24 percent of the runoff from Areas I, II, and Ill as
illustrated on the drainage map. Area IV currently drains across the undeveloped property lying /.
to the south of the subject tract. Area V drains toward the west onto undeveloped land but the
runoff enters a drainage retention structure located on Tract D of Ponderosa Place. Runoff from
the retention structure enters Southwood Terrace Section One in an easement in the rear of lots
along Bluestem Circle. An earthen berm was constructed all along the northern boundary of the
subject tract , preventing direct runoff from flowing onto the lots located in Southwood Terrace
Section One.
The obj ective o f this report is to document the drainage impacts subsequent to development of
the property.
Methodology
The rati onal method was used to compute the 5, 10 , 25, 50 , and 100 year storm events in
accordance with City drainage design standards . The rational formula is expressed as :
wher e Q =
c -
I -
A -
Q =CIA
peak discharge in cubic feet per second (cfs)
runoff coefficient
r ai nfal l intensity in inches per hour
(1)
land area in acres that contributes stormwater runoff that passes th ro ugh or at a
desi g nat ed des ig n po int.
EE!i !30 8/DRAIN-l .TX T 2122195
The triangular hydrograph was used to calculate time-variable flow rates used in sizing the
proposed drainage retention basin. The base of the triangular hydrograph was 3.0 times the time
of concentration.
Table 1 presents a summary of storm runoff calculations for each area within the subject tract.
Under predevelopment conditions the runoff coefficient ranges from 0.35 to 0.42. With the /
construction of pavement of buildings , the postdevelopment runoff coefficients will be
approximate! y 0. 95. Consequently, the post-development peak runoff flow rates will be higher.
.
The entire tract will be re-graded to drain toward the west corner of the site. All but a few feet
of the property along Longmire will be able to drain toward the west. The proposed method for
managing the increased runoff will be discussed separately in the following sections.
Area I
Area I , consisting of 0.575 acre, currently drains toward the northwest where runoff accumulates
along the earthen berm. The runoff proceeds alongside the berm toward the northeast, emptying I
onto Longmire Street. The predevelopment peak 100 year flow is 3.02 cfs. Because Longmire .
is a minor thoroughfare, it has more than adequate capacity to handle existing flows. However,
the proposed development will remove virtually all of the predevelopment flow from Longmire
and take all drainage to the west of the property.
Area II
Area II, consisting of 0.239 acre, currently drains toward the northeast and runs in sheet flow
over the curb onto Longmire Street. The predevelopment peak 100 year flow is 1.25 cfs. (
Because Longmire is a minor thoroughfare, it has more than adequate capacity to handle existing
flows. However, the proposed development will remove virtually all of the predevelopment flow
from Longmire and take all drainage to the west of the property .
Area III
Area III , consisting of 0.580 acre , currently drains toward the east and runs in sheet flow over
the curb onto Longmire Street. The predevelopment peak 100 year flow is 2 .54 cfs. Because /
Longmire is a minor thoroughfare , it has more than adequate capacity to handle existing flows.
Howev er , the proposed development will remove virtually all of the predevelopment flow from
Longmire and take all drainage to the west of the property.
Area IV
Area IV , consi s ting of 1.608 acre , currently drains toward the south and runs in sheet flow onto
the und ev eloped land to the south , consisting of Tracts G2 and GI of Ponderosa Place.
Predevel opment peak 10 0 year flow is 7.44 cfs. However, the sheet flow will be interrupted /
b y c ons tru_c_tjrrg _a __ s_~_al~ along the southern bo~ndary of Area IV. Some re-grading will be
perfo r me d in A rea IV to keep the flows on-site. These improvements would completely
e l i mi nate runo ff onto Tracts G2 and G 1.
E E!.': 3UX /l)lV\ IN-1 . T X T 2 212 2 /9~
Area V
Area V , consisting of 3.022 acres, currently drains toward the west and runs in sheet flow onto
the undeveloped land to the west, consisting of Tracts D of Ponderosa Place Section Two.
Predevelopment peak 100 year flow is 15 .11 cfs . It will be necessary to detain the runoff so
that the postdevelopment peak flow will not exceed the predevelopment peak flow. Also, the
earthen berm along the north side of Area V will be maintained so that sheet flow from the
northern portion of Area V will not flow onto the rear of the lots at the end of Longmire Circle.
Proposed Retention Basin
The proposed retention basin was designed in an irregular shape with earthen walls on all sides
and a sloping entrance into the basin. The proposed basin will be situated at the far western
corner of the subject tract and will extend over the top of an existing sewer line into the adjacent
property. Drainage easements were granted by the owner of the adjacent property for the
exclusive use of drainage retention and runoff conveyance. These easements are recorded in
Volume 1473, Page 220 and in Volume 1229, Page 070 of the Deed Records of Brazos County.
The latter deed provides for the conveyance of runoff downstream of the proposed retention
basin into the existing retention basin on the adjacent property.
The proposed basin is approximately divided into equal halves on the subject tract and on the
adjacent tract. It will extend over a 20 foot utility easement which contains an 8 inch sanitary
sewer line. The flowline elevation of the sanitary sewer is 303.4 feet where the proposed
retention basin would be. The top of the pipe is at an elevation of approximately 304 .5 feet,
and the bottom elevation of the proposed retention basin is 307.5 feet. Thus, there is at least
3. 0 feet of vertical clearance between the existing sewer pipe and the bottom of the proposed
retention basin. All of this is depicted on the drainage map which accompanies this report.
Proposed side slopes of the retention basin will be no steeper than 4: 1 (The required volume
of the retention basin was derived by first establishing the areal extent of the basin and then
determining the required depth from a routing analysis in which:
Q -Q = dV in out
where Qin = unregulated flow rate into retention basin, cfs
Q0 ul = regulated flow rate out of retention basin , cfs
dV = change in volume in retention basin , cu.ft.
(2)
I
Succes s iv e iterations were carried out over successive 60-second time steps from the beginning
of the 100 year storm until the end. Refer to Table 2 . The 50 , 25, 10, and 5 year storms were
an alyzed in the same way and are shown on Tables 3 , 4, 5 , and 6, respectivel y .
EEi/ I 30X /IJRAIN--l .TXT 3 2122 /95
I
An orifice located at the far end of the structure provides a gravity outlet for the retention basin.
Using the standard orifice equation (below) the discharge flow was calculated:
where C
A
h
QOUI = CA/(2gh)
= orifice coefficient, 0.61
A X--
Afull
= cross sectional open area of orifice, sq. ft.
= hydraulic head at centerline of orifice, ft.
(3)
/
By varying the number and diameter of the orifice, it was possible to reach a proper balance
between the retention basin depth and the peak flow out of the basin. It is necessary to achieve
a peak flow which is equal to or less than the predevelopment peak flow. In this case, the
predevelopment peak 100 year flow is 15.11 cfs and the postdevelopment peak flow from the
retention basin is 15.56 cfs. However, the retention basin receives a peak flow of 65.95 cfs due /
to the fact that the site will be re-graded so that the retention basin will receive all of the runoff.
Refer to Figure 1 which illustrates the performance of the retention basin during the 100 year
storm.
An orifice with a diameter of 18 inches provides sufficient restriction to the outlet of the /
retention basin such that postdevelopment flows are at or near predevelopment conditions.
Therefore, any downstream impacts are properly mitigated by the proposed retention basin.
Summary
The following table summarizes the results of this analysis.
Table 7 -Summary of Results
Predevelopment Peak Flow, Pos t-Development Peak
Storm Frequency , year cfs Flow, cfs
100 15 .11 15.56
50 13.30 14.29
25 11.85 13.20
10 9.91 11.61
5 9 .31 11 .08
EE ~'I 30 8 /DRA!N-4 .TXT 4 2n2/95
Of course, it is obvious that the postdevelopment peak flows are slightly higher than
predeveloped conditions. The City is urged to consider the following points:
1. The absolute differences between predevelopment peak flows and postdevelopment peak
flows are relatively minor, which complies with the spirit of the Drainage Ordinance .
2. The discharge from the proposed retention basin does not flow uncontrolled onto
downstream property, but will enter the existing retention basin on the adjacent tract.
The existing retention basin has an outlet control structure to limit its downstream
discharge.
3. The developer will perform extensive re-grading so that all areas of the site will drain
to the west corner of the property, eliminating nearly all runoff onto Longmire. By
doing this, the proposed development will virtually eliminate all existing impacts on
Longmire. This goes far beyond the spirit of the Drainage Ordinance.
4. As proposed, the retention basin has earthen walls which can be easily maintained. If
the City should require an enlargement of the proposed basin, it would entail the
construction of vertical concrete walls, posing a safety hazard. Further, concrete retaining
walls would be expensive to construct and to more difficult to maintain than the proposed
earthen walls.
5. The outlet of the retention basin is a simple orifice which is easily maintained.
Additional weirs and/or more complicated structures might function better initially but
over time may become damaged or fall into disrepair.
The drainage improvements to be implemented are as follows:
1. Re-grading will be performed so that the site will drain to the west corner of the
property, eliminating nearly all runoff onto Longmire.
2. Construction of a retention basin to serve Area V.
3. All runoff from the site will flow through the proposed retention basin which in turn
empties into an existing retention basin. This plan provides double mitigation of rainfall
runoff impact.
Drainage onto Tract D
Tract D of Ponderosa Place Section 2 is a 7.02 acre parcel of land which joins the western
boundary of the subject property. In 1990 the City of College Station approved a drainage
report1 (Galindo 1990) for Tract D . A copy of the report is contained in the Appendix.
That report presented calculations for a proposed detention facility on Tract D and determined
that its volume should be 29 ,400 cu .ft. With the exception of sub-basins 1-3 and 1-5, everything
on Tract D was designed to drain into the detention facility. A map showing the sub-basins is
depicted in Exhib it 6 of the Galindo report.
G a lindo Engineers & Planners, Drainage Repon -College Station Professional
B u ild ing, Lot 1, Block 1, Remington Subdivision, College Station, TX, November
1990 .
EEJ /J 308/DIU\ 11'--1 .TXT 5 2122 /95
Sub-basin 1-7 was also included in the runoff calculations for the design of the detention facility
on Tract D. Sub-basin 1-7 consists of 1.8 acres from the western part of Tract B, the subject
tract in the present study. The design criteria for the detention facility on Tract D (from the
Galindo report) are presented below .
Detention facilitv des ign:
Total Drainage Area .......... .
Peak 100 year predevelopment inflow
Peak 100 year postdevelopment inflow
Sub-basin 1-7:
Drainage Area . . . . . . . . . . . . . .
Peak 100 year predevelopment inflow
Peak 100 year postdevelopment inflow
7.5 acres
25.3 cfs
38.6 cfs
........ 1.8 acres
........ 6.1 cfs
......... 6.1 cfs
Sub-basin 1-7 constitutes approximately 24 percent (1. 817.5) of the drainage area of the detention
facility on Tract D. Sub-basin 1-7 constitutes approximately 24 percent of the predevelopment
runoff and 16 percent of the postdevelopment runoff of the detention facility on Tract D.
The runoff from sub-basin 1-7 has been provided for in the design of both Tract D and Tract /
B (the subject tract). In the present report, all of sub-basin 1-7 will drain into the retention basin V
described earlier. Because of the redundancy in design , it would now be appropriate to credit
Tract D with an allowance for the volume of Sub-basin 1-7.
Drainage agreements which exist between the owners of Tracts D and B provide that the
detention facility in Tract D will accept at least 12 cfs from the retention basin on Tract R
From an earlier calculation presented in this report, the 100 year discharge from the proposed
retention basin is 15 .56 cfs. This exceeds the 12 cfs provision by 3.56 cfs. However, the
drainage calculations for Tract D contained an allowance of 6.1 cfs that is now included in the t~
15 .56 cfs on Tract B. Therefore, the peak capacity which could be attributed to the detention /
facility would be 18.1 cfs (12.0+6.1), which is 2.54 cfs over and above what is now being
proposed . Therefore, the proposed retention basin that will serve Tract B could have been
designed to release up to 18.1 cfs rather than 15.56 cfs into the detention facility on Tract D.
The flow path between the retention basin on Tract B and the detention facility on Tract D j
would be over the surface of the ground at the interface between the two systems. The existing
earthen berm along the northern boundary of the private drainage easement will be maintained
by the owners of Tracts D and B in a manner which would prevent the overflow of runoff
toward the north.
EEL'1308/D RAIN ..J .TXT 6 21221 95
I
I
I
Appendix
Drainage Report
College Station Professional Building
Lot 1, Block One
Remington Subdivision
College Station , TX
I
I
I
I
·, -.....
GALINDO ENGINEERS AND PLA1YNERS
1900 West Villa Maria
Ms. Debbie L. Keating, P.E.
Drainage Engineer
City of College Station
College Station, TX 77840
SUbject: Drainage Report
Bryan, Texas 77801
November 13, 1990
College Station Professional Building
Lot 1, Block One
Remington Subdivision
College station, TX
Dear Debbie:
(409) 823-1919
Following our nt.D"nerous conversations on this project please find enclosed
the referenced report which supersedes our previous report of Septerrber 25,
1990.
The project area is a 4.00-acre tract Jaiown as Lot 1, Block One, Remington
Subdivision, a part of the 7.00-acre Tract D, Ponderosa Place Section Two,
College Station, TX.
An effort has been rmde to meet the requirements of the City of College
Station regarding stotmTater rranagement and the standards of the developer,
College Station Professional Building Ltd.
our report is being subnitted to you in duplicate with the necessary
exhibits to il 1 ustrate our findings. A separate sheet, 24"x36" in size,
titled "Grading and Drainage Plan" is being sul::mitted separately, in 13
prints. as part of the Site Plan review application.
Also enclosed is the Developnent Permit Application signed by the Developer
of the project.
Sincerely,
GALINOO ENGINEERS AND PLANNERS
Christian A. Galindo, P.E., R.P.L.S.
President
I
I
I
I
GALINDO ENGINEERS AND PLANNERS
OJLLEGE STATIOO PROFESSIOOAL BUILDINO
DRAINAGE REPORT
1. TRACT DESCRIPTION
.... · . ., , .... -·.
The College Station Professional Building tract covers 4.0 acres of land
and is legally described Lot 1, Block One, Remington Sulxiivision, a
replat of Tract D, Ponderosa Place Section Two, College Station, Texas.
Exhibit 1 shows the location of the tract, the adjoining parcels of
land and the zoning therof and the utility easenents platted in adjacent
properties.
The general area topography (2' contour lines) is shown in Exhibit 2.
The datun in this Exhibit i.! approrlrre.tely 10 feet higher thM the
datun selected for this project and used throughout this report.
The detail topography of this tract (0.5' contour lines) is depicted in ·
Exhibit 3 and it is also depicted in the 24"x36" blueprint of the
Grading and Drainage Plan which is being sul:mi tted separately. That
blueprint shows the detailed grading plan, proposed ponding, buildinq
stonn drain into the pond and pond outfall structure following the
design criteria descdbed below.
A site bench mark elevation of 300.00 feet was selected for the top of
the sewer rranhole located on the northerly right of way line of Rock .
Prairie Road, just west of this tract.
A cartiuter generated surface rrap is shown in Exhibit 4. The only
- 2 -
GALINDO ENGINEERS AND PLANNERS
possible outfall fran Lot 1. Block One, Remington Sul:division , after
develoµnent is at the location of the existing 10' utility easement
where a 4'-wide drainage ditch now exists. Lot 2 and the adjoining .
Tract B, Ponderosa Place Section Two have rrore imnediate drainage paths
through easements just to the north of their boundaries as seen on
Exhibit 1.
The land in the Remington Subdivision and in the adjoininq Tract B is
vacant and the existing grotmdcover can be classified as pasture.
This subject tract is zoned AP. The tracts to its imnediate north and
west are zoned R2 and are developed. The tracts to the east are zoned
C-2 and one is partially developed (Tract G, Ponderosa Plac~ Section
Two).
2 • FLOOD PLAIN
The adopted Flood Insurance Study does not identify the existence of a
100-flood plain near the location of this tract.
3. DESIGN CRITERIA
'As indicated above there is only one possible nmoff outflow frc:rn this
4.0-acre tract through the existing 10' utility easement that discharges
onto the surface of a culdesac known as Longleaf Circle in the Southwood
·Terrace Section One Subdivision . This easement currently includes a
street light pole and av-section concrete lined charmel (4.00' wide,
0. 35' high) connected longitudinally-on its eastern side to a 4-car
- 3 -
I
I
GALINDOENGINEERS AND PLANNERS
(duplex residential building) concrete parking lot.
Lot l, Block 1, Remington Subdivision will contain a 3-story, 55,000
s.f. medical office ccrrplex, with an attached exercis~ pool. and a
249-space parkinq lot. A rtmoff detention scheme is therefore
contell'lated and is being designed. Different ownership and lack of
developnent plans for Lot 2 make a design of a rimoff mitigation scheme
for this lot not appropriate at this time.
4. RUN OFF CAL~TIOOS
Exhibit 5 sU'TTTlarizes the nmoff calculations for this tract using the
Rational Method. This Exhibit lists, in tabular form, the constants and
factors used. Q for a return period of 100 years was used for
subsequent analysis and calculations.
Exhibit 6 shows the nmoff sections for pre-and post-developnent
conditions. The rate of nmoff for a 100 year storm at the outfall
point goes frcm 16.9 cfs (pre-develo~t, or maximum allowable nmoff)
to 34.0 cfs (post-develoP'T'!eJlt).
5. ON SITE DETI:NTION
Exhibit 7 shows the Mass curve calculations and provides a preliminary
sizing of the required detention in the order of 20,000 cf.
Exhibit 8 is a plot showing the ponding availability wi~hin the ·patkingr
~as delineated in the grading plan given in the 24"x36" blueprint
- 4 -
I
I
I
I
GALINDO ENGINEERS AND PLANNERS
drawing. The pond is located at the northernmost end of Lot 1. This
Exhibit also shows the design characteristics of the circular (pipe)
weir selected.
Exhibit 9 is the Inflow/Ouflow Simulation for the detention basin.
Maximum ponding required is calculated to be 2 9, 400 cf ( 77% of total
ponding availability) and TT'0.Xinun corresponding water rise is
calculated to be 297.49' (top of pond embankment is desicmed to be
298.00' to provide 0.5' of freeboard). Maximum attained Q and v l.mder
these conditions is 13.11 cfs and 7.41 fps respectively.
The outfall structure fran this detention facility will consist of a
/I
' .
/ '6 .l.s>' diameter pipe, 6" 1 ong, either encased in a concrete frarre with wing
walls as shown on the Grading Plan blue print or a longer ~diameter t!d_
pipe sliced 2/1 at both ends and placed through the pond embankme.11t.
The first alternative provides better entrance control at the weir
structure but it is rrore expensive.-The entrance control factor used
in this report is an average 0.7. The outlet frcrn the weir will consist
of a concrete lined fll..D'Tle to connect with the already mentioned existing
facilities at or near the property line.
The bui 1 ding wi 11 drain roof water through two 10" downspouts to a
level nearly 3 feet below finished floor. A calculated 100-'.'r Q fort=
0.6 minute equals 8.7 cfs. This runoff is to be taken to the detention
pond and thus it is to traverse tmder the parking lot . Since the
- 5 -
liALINDO..CNGINEERS ANDI'LANNERS
available depth tmder the parking lot is limited, a double b.1rrel
culvert consisting of two 15" pipes has been design~. These pipes wil i
at no time be closer than 0.79' to the finished parking lot grade.
Each pipe will carry 4.5 cfs under the design conditions shown in the
Grading Plan blueprint.
7. GERTIFICATIOO
-:-~: •... ~ i.
•. "! -'· ..
. ·' ... ·~ . ,"';
,·_-. , • ..., . ;'t~·.-...· ..
I hereby certify that this design and report were pre;iared by me in
accordance with the provisions of the City of College Station Drainage
Policy and the requirements of the Developer.
CHRISTIAN A. ~INDO, P.E. I 53425, R.P.L.S. I 4473
Noverrber 13, 1990
- 6 -
"•1111 Ill ,,,.,_ I -·--
............ ~
00.. ..,,,..,u,, ..
---··-_. .. ,_,_ -_ .......... --··-.. ---~3~~t~0~~1
..... ---.. ·---37&;·;
;z «' , . ..... _
~;:·F:.:-~.::,. -··
~~'f., .~~-?.-.. ... ;.··-..
. I ' \,\
l h"l lll .. .._ I -··· ---::::: ~ --:"': .. -::::-:=. :.. -::: -....... __ ,,, -............... -........ -:::: .... -::.:::... ·:....-:-_-::..::.-:: -···· ............ ·--.... ·-::-.:::::. .... ·-·----··
...... _, -·-
... _ _ ,. ...... __
__ ..._ -_.,_ .... ... ......... _ ....... ,_,_., .. .
:-.. ::::... -.:-~-;-.:::.. :.:.: = --=-.. :·.::..:.:.::. ::--.:::::: --_______ ,._ -·-,._ .. ·-·-... ·-::::::=.. -·-·-.. --· ..
~~
"'" ..... ,.... ·--~~
l .-• -..... _ ... _ , .. .. .. -....... ,-.... ·-.......... ... '''" .. """-..... ---,_,., ·-...... ,_ .... -..... -···· .. , .. .._ ........... --!LiO.--.. ·-" . ~!!':! " ciJL
\ "",. :c:.... )
...... -.... --···-, ... '--" ........... '""-........ ·-~ ...
:~.~::=:-:.:..-:·:--.:.:; 4 ,. =~~
=-:~.:::= .:.::·~:: ......... -... ---····-.._ ....... -... -....... i. .... C.••···-
::;.·. "::..:
::.:::::::::: ... ~.::·-:· ::· " __ ,, ............ ~
:· .... :.::·":::. :.:·:.:~.-. : ..
........... _, ...... . .............. .. ..
POND EROSA PL ACE
uc11on two
Co lleg e. St ;lll on . 1 e .~as
Sei>L 'U8 2 .· :".I oo ·
~ilt~~:' ,.,_ {.:..:: . .: ·'' ....... ; .. ·· ie• <iATrVAlV€ -1 --Q "' /' . ' ~t(V~Y£J Jli A'!l i' f~i ---] r~~~-~Q.-.. 1•• g,t._l t >"4 V( ~,oo It.< I •' ;,'VO wit' n.o , .... , o.o .. · -It' Q41f VAlVt "-, !:!.f_HtQ. l I JI. I' .vc; x---I '\. ....... · / ',f ! t' ~~ ~ c,.·I '('r#r.:r ~D --:-l:Jkul 5-1n1ef5 . ._:;r-__ I I STREET UQHT --!MANHol E NO. l je• A/C W~lER _l~.E __ _ ';, l'se~R llNE NO. I e-v c P !l ~-~ e•iS• 'H ~ G•TE IALVE . \ \ I -·--. +· ro-').. -'(~ ./ ---~ 1111 •1'fllllANI lt.,;,I (~· -· .~ ' ,. _____ _._ ____ -'"'H~• I 4l'l, ... I U I JO ill I IA-tO •I.AIM.I.)-•' -· . " 1l;' .. · ·~ ,~ .---· ,.. [illi{eLLJ!!Hl-J i "\ ~ /" _ .. Ii~ I l~ 4· U•ll ·•ln I M • .. I ~ I --~-I-a, ----~ -. .'I I• I· RO . ~ ~ ~~ ~~_!)U\~ r
875 975 107 5 1175 1275 1.375 14-75 1575
1675 1675
1575 1575
1 4-75 1475
. 1375 1375
Q
~ SCALE 1:, 00 \J
\)
\.)
~ 1275 1275
1175 1175 ~
I
~ 1075 1075 #CJ~:
ASSt1AlfED C'L.:!:V.
~~ CO"'( ??)V R:..S
975 975 875 9 7 5 107 5 11 7 5 1275 137 5 14-7~
1 "'"
. '
I
0 ...,.· c
ff)
0
"' 0
")
------·-----\
. '
c; 0 0
cc lO ,..·
(Jl <fl 111 N (\.) N
N O/; ~/l.3 7...37
/ \
I
I
I
I
\
' \
\
\
\
\
\
\
\ -------1
I
I
I
I
I ---------.,
/
/
/
/
/
-
Job: 10-90
Client: Re1in9ton Land Dev.
Date :. 28-0ct 1990
RUllOFF CALCULATION, RATIONAL HETHOO
COLLEGE STATION PROFESSIONAL BLOG.
Co 11 ege Stat ion, TX
(Countv : Brazos)
Tc : 20.000 (1in.)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Section Soi I
Type
A
Acres
C Veloc. le19th T cone., 1in.
fps ft Calcul. Used
I
5 yrs
I I
10 yrs 25 yrs
I I Q (cfs) Q (cfs) Q (cfs) Q (cisl Q (cis)
50 yrs 100 yrs ~yrs 10 yrs 25 yrs 50 yrs 100 1rs
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Before l11prove1ents
-------------------1-1 Pasture 3.3 0.40 1.50 500 5.56 20.0 5. 48 6.21 7. 12 8.08 8.43 7. 2 8.2 9.4 I 0. 7 11. 1
1-2 Pasture 0.5 0.40 1.50 500 5. 5 6 20.0 S.48 6. 21 7. 12 8.08 8.43 I. 1 1.2 1.4 u 1.1
1-3 Pasture 0.2 0.40 1.50 150 1.67 20 .0 5. 48 6.21 7. 12 8.08 8.43 0.4 0.5 0.6 0.6 0. 7
H Pasture 1 . 7 0.40 1. so 400 4.U 20.0 s. 48 6.21 7. 12 8.08 8. 43 3.7 4.2 4.8 s. 5 ) . l
1-5 Pasture 1. 1 0.40 1. so 400 4.U 20.0 S.48 6. 21 7. 12 8.08 8. 43 2.' 2. 7 l. I u u
H Pasture 0. 2 0.40 I.SO 400 4.U 20.0 5.48 6. 21 7. 12 8.08 8. 43 0.4 0.5 0.6 O.o •J.1
1-7 Pasture 1.8 0.40 1.50 400 4.H 20.0 5. 48 6.21 7. 12 8.08 8.43 3.9 4.5 S. I s. a 6. I
ERR
TOTAL 8.8 19. 3 21.9 25 . I 28.4 29 . 1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------After l11orove11ents
-------------------1-1 Cone/gr as 3.3 0.80 4. 00 600 2. 50 20.0 5. 48 6.21 7. 12 8.08 8.43 14. s 16. 4 18. 8 2U 22.3
1-2 Conc/gras 0.5 0.90 4. 00 600 2. 50 I 20.0 5.48 6. 21 1. 12 8.08 8. 43 2.5 2.8 3.2 3.b u
1-3 Concret 0.2 0.90 4. 00 100 0.42 20 .0 5. 48 6. 21 1. 12 8.08 8. 43 1.0 1. 1 1.3 1.5 1 . 5
H Pasture 1.1 0.40 1.50 400 4.H 20.0 5.48 6. 21 7.12 8.08 8. 43 3.7 4. 2 4. 8 5.5 u
1-5 Pasture 1. 1 0.40 1.50 400 4.H 20.0 5. 48 6. 21 7. 12 8.08 8. 43 2.4 2. 7 3. I u 3. 1
1-6 Pasture 0.2 0.40 1.50 400 4.U 20.0 5.48 6. 21 7.12 8.08 8. 43 0.4 0.5 0.5 0.5 J. 1
1-7 Pasture 1.8 0.40 1.50 400 4.U 20.0 s' 48 6.21 7.12 8.08 8.43 3.9 u 5. 1 s. a u
ERR
TOTAL 8.8 28. 4 32.2 36.9 !3 . 3 -----------------------------------------------------------------------------------------------------------------------------------------------------------------· ------------------------------------------------------------------------------------------------------------------------------------------------------------------
Hax . ll lowable runoif : Predev . runoff fr<MI Sections 1-1 and 1-4 : + 1-'7
On site detention reauired : ~ostdev. ru10if iro1 sections 1-1, 1-2, 1-3 and 1-4 : 11.0
22 .1
lU
25 .0
14 . 2
28 . 1
16. 2
32 .1
1 s . 3
H .Q
8 7 5
1675
15 75
14-75
. 1375
Q
~
\)
(J
\J
~ 1275
1175
975 1075 ----, 175 1275 1375 1475 1575
AiJid, 2Z, l~C/O •
1675
1575
1 4-75
1375
SCALE 1: 100
1275
1 , 75
1075 1 075 t/t:' n!J:.:
975 L--~..l.-~~c=---'-~---ll....l---L~_..!1.~.l.-1~~L-~..L...l..___L_~_!_---JLL~.L.1..~_J 975
875 97 5 1075 1175 1275 1375 14-75 1 57~
A.SSt/M£D .:L£:V.
,t=t:'~ CO# ??:Til ,cc::.s
£JCHt61T . >
Job: lo-90 "ASS CURVE CALCULATIONS
Date: 28-0ct-90 (100-year storm)
BASIN t 1
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
TIHE , t C t A I ( 100) Q in 60 • t V in Q out V out Delta V
----------------------------------------------------------------------------------
5 3.950 14. 76 58.30 300 17,Hl 16. 90 5,070 12, '21
10 11. 6' 45. 97 600 27,585 10I1'0 17,W
I
15 9.73 38.U 900 34, 598 15, 210 19,388
20 8. 43 33 .30 1, 200 39,960 20,280 19,680
I 25 7." 2!. 54 1,500 U,304 25,350 18,954
30 6.75 26.65 1, 800 47' 962 30,'20 17 ,5H
35 6. 16 24. 35 2' 100 St, 128 35,490 15.638
40 5.69 22 . 47 2,400 53.923 40,560 13,363
I 45 5.29 20.90 2, 700 56,430 45,630 10,800
50 4.95 19.57 3,000 58,707 50,700 8.007
55 4.66 18. 42 3,300 60,794 55, 770 5.024
60 4. 41 17. '2 3,600 62,725 60,UO 1,885
65 4.19 16. 54 3,900 64,522 65,910 (1,388)
70 3. 99 15. 7 6 4,200 66,205 70,980 ( 4. 775)
75 3. 81 15.06 4,500 67,788 76,050 (8,262)
80 3.65 14 .0 4,800 69,285 81, 120 ( 11, 8 35)
85 3. 51 13.86 5, 100 70,704 86' 190 ( 15 I 486)
90 3. 38 13. 34 5,400 72,055 91, 260 (19.205)
95 3.26 12. 8 7 5,700 73 ,345 96.330 (22 .985)
100 3. 15 1U3 6,000 74,580 101, 400 (26 ,820)
105 3.04 12.03 6,300 75,764 106,m (30.706)
110 2.95 11.65 6,600 76 ,902 111, 540 (H, 638)
115 2.86 11 . 30 6,900 77 I 999 116 I 610 ( 38 I 611)
120 2.78 10.98 7,200 79 ,056 121, 680 {42,62')
--------------------------------------------------------------------------------------------------------------------------------------------------------------------
....= u..
~ < > ~ w
I ,.,.. ..
I ·-
I !
. I
TXHllJtr 8
COLLEGE ST A TION PROFESSIONAL BUILDING
PONDING AVAILABILITY
299 .0
1(}-9()
298.0
297.0
296.0
295.00 20 40
STORAGE VClU~ 1 CCO CF.
POND ING AVAILABILITY
----------------------------------------
Elev . AREA h De I V Cum V
ft . s. f . ft. cu ' ft . cu.ft .
---------------------------------------------
295.0 0 0.0 0 0
295 .5 5,000 0.5 I, 250 1,250
296 .0 13 ,800 0.5 4,700 5,950 -l . I '\
297. 0 16,400 1.0 15 J 100 21, 050 1%.1
298 .0 17 '400 1. 0 16,900 37 J 950
IEIR DESIGN (ORIF ICE)
----------------------
h A Q v
---------------------------------------------
2.00 1.5 0 I. 77 14.04 7.94
2. 50 1.50 1.11 15 .70 8.88
2. 70 1.50 1.11 16 '31 9.23
I
I
I
~Xfffi:lfl
Job : 10-90
Date : 28 -0ct-9 0
INFLOl-OUTFLOI Sl"ULATION
( 100-year storm)
BASIN I 1
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
T lme, t V in OV in + V ave Contour h Q out V out Cum . V sto .
111in . c.f. V sto . c.f. tlv . ft ft cfs c .f. v out c.r .
------------------------------------------------------------------------------------------
0 0 295 .00
IT,'91 8,745 296.19
5 17,(91
25 ,620 20,573 296 .97
10 27,585
29,3(6 25,840 297 .28
15 34,538
31,020 28,339 297 .(3
20 39,960
31,503 29,331 297.(!
25 U,304
31,233 29,(0( 297.49
30 H, 962
30,(65 28,882 297.46
35 51,128
29,362 27,964 297.41
(0 53,923
28,033 26,780 297.34
45 56,00
26,556 25 ,417 297 .26
50 58,707
2',986 23,942 297.17
55 60' 79(
23,366 22,(01 297.08
60 62,725
21 ,729 20,830 296.99
65 U,522
20, 101 19,260 296.88
70 66,205
18,517 17,725 296.78
75 67,788
16,992 16 ,243 296 .68
80 69,285
15,537 14,827 296 .59
85 70,70(
14, 162 13,486 296.50
90 72,055
12,87' 12 .229 296 .'2
95 73 ,3'5
11,678 11 ,061 296 .34
100 H,580
10,578 9,986 296 .27
105 75 ,76(
9,574 9,005 296 .20
110 76 ,902
8,668 8, 120 296 . H
115 77 ,999
7 ,857 7,328 296 .0 9
120 79 ,0 56
o.u 6.55 1,96' 1,964 15 ,526
1.22 10.96 3,287 5,252 22,333
1.53 12.29 3,688 8,9'0 25,658
1.68 12.87 3,862 12,801 27, 159
1.74 13.09 3,928 1',729 27,575
1. 74 13.11 3, 933 20,663 27,300
1.71 12.99 3,898 24,561 26 ,567
1. 66 12. 79 3, 836 28 ,397 25,526
1.59 12.51 3, 75' 32.151 H,m
1.51 12.19 3,658 35 ,808 22,898
1.H 11.83 3,550 39,359 21,rn
1.33 11.45 3,434 42 ,793 19,932
1.H 11.03 3,310 H, 103 18,'19
1.13 10.56 3, 168 '9 ,271 16,934
1.03 10.01 3,022 52,293 15,m
0.93
0 .84
0.75
0. S7
0.59
0.52
0.45
0.39
0. 34
9.58 2,875 55 ,168 1',117
9.09 2, 726 57,89' 12 ,811
8.59 2,578 60,471 11,584
8.10 2,00 62 ,901 10,W
7.62 2,285 65 , 186 9,39'
7.14 2, 1H 67 ,328 8,436
6.68 2,003 69 ,33 1 7,572
6.23 1,869 71 ,1 99 6,7 99
5.80 1,HO 72.939 6,118
DEVELOPMENT PERMIT
PERMIT NO . 99 -5003 2 8
College Station Professional Building Detention Pond
FOR AREAS OUTSIDE THE SPE CIAL FLOOD HAZARD AREA
RE: CHAPTER 13 OF THE COLLEGE ST A TION CITY CODE
SITE LEGAL DESCRIPTION:
Remington Subdivision Lots 1 & 2
DATE OF ISSUE : 12 /3 1/1999
OWNER:
Walt Schoenvogel
P.O . Box 602
Brenham , TX 77834
(409) 836-5482
TYPE OF DEVELOPMENT:
SPECIAL CONDITIONS:
SITE ADDRESS:
1605 Rock Prairie Road
DRAINAGE BASIN:
Bee Creek Tributary A
VALID FOR 12 MONTHS
CONTRACTOR:
RE-GRADING OF THE DETENTION POND AREA ONLY
NIA
The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate
construction site in accordance with the approved erosion control plan as well as the City of College Station
Drainage Policy and Design Criteria. The Owner and/or Contractor shall assure that all disturbed areas are sodden
and establishment of vegetation occurs prior to removal of any silt fencing or hay bales used for temporary erosion
control. The Owner and/or Contractor shall also insure that any disturbed vegetation be returned to its orig inal
condition , placement and state . The Owner and/or Contractor shall be responsible for any damage to adjacent
properties, city streets or infrastructure due to heavy machinery and/or equipment as well as erosion , siltation or
sedimentation resulting from the permitted work.
An y trees required to be protected by ordinance or as part of the landscape plan must be completely fenced before
any operations of this permit can begin .
In accordance with Chapter 13 of the Code of Ordinances of the City of College Station , measures shall be taken to
insure that debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing
drainage facilities .
I hereby grant this permit for development of an area OUTSIDE the special flood hazard area. All development
shall be in accordance with the plans and specifications submitted to and approved by the City Engineer in the
development permit application for the above named project and all of the codes and ordinances of the City of
Coll e tation th t app~
A Date
Owner/ Agent Date
Contractor Date
DEVELOPMEN'f SERVIC~S
TRANSMITTAL LETTER
Address :
CA -5J::J322
Date:
Phone : 052-%74
Fax : CcB't-i -=42..Y:S
We are transmining the following for Development Services to review and comment: (Check all that apply.):
0 Master Develop ment P lan w/ D Redlines efnevelopment Permit App .
0 Preliminal)· Plat w/ D Redlines D Conditional Use Permit
0 Final Plat w/ D Redlines 0 Rezoning Application
0 FE?\1.A.. CLOMA/CLOMR/LOMA/LOMR w/ D Redlines 0 Variance Request
0 Site Plan w/ D Redlines D Other -Please specify
[](,....Grading Plan w!O Redlin es
D Lc.ndscape Plan w1D Redlin es
D Irrigation P lan w!D Redlin es
0 Building Construction Documents w!O Redlin es
INFRASTRUCTURE AND ENGINEERING DOCUMENTS
All infrastructure documents must be submitted as a complete set.
The following are included in the complete set:
0 Waterline Construction Documents w/ D Redlines
0 Sewerline Construction Documents w/D Redlines
0 Drainage Construction Documents w/ D Redlines
0 Street Construction Documents w/ D Redlines
D Easement application with metes & bounds decsription
D Drainage Letter or Report w/ D Redlines
D Fire Flow Analysis w/ 0 Redlines
Special Instructions:
TRANSMITI AL LETIER
TRANSMIT.DOC 03 /2Ji99
D TxDOT Driveway Pennit
D TxDOT Utility Permit
D Other -Please specify
I of l
FOR OFFICE USE ONLY
CASE NO.:
DA TE SUBMIITED:·-----
DEVELOPMENT PERMIT
MINIMUM SUBMITTAL REQUIREMENTS
--,L $100 .00 Development Permit Application Fee.
__ V Drainage and erosion control plan, with supporting Drainage Report two (2) copies each .
.ti6__ Notice ofintent (N.O.I.) if disturbed area is greater than 5 acres .
LEGALDEscRIPTioN l-0--r 1<>1-1.. &..'OC .. ::f .. ONE) gP...)(Y)i Ntr-rw fu>f20 1\J1 12 1w
APPLICANT (Primary Contact for the Project):
Name TumN \Y\E.. \CA\..f=-(Mt::>~)
Street Address ,ZCZ?\ I~ A"YE . 0 , ~ A
I
City Cou.:e.V;E.. ~-n~
E-Mail Address m d 'Jcs @ <j~e... D.e.t State I x. Zip Code (7 Bl.1 ()
Phone Number (p°'\ 2.7-S'!>?C\
PROPERTY O\VNER'S INFORMATION:
Fax Number Lt>47,-yZL..\3,
Name L'1AL1 Sc~cw~
Street Address ?.c, £zD0. <.ooZ., City _ _,.6'"""-"\2..=i::=~:.........:.H....:A_..:._W\--'--------
E-Mail Address State IX Zip Code 778?:> '-i --------------
Phone Number (t.\\f'I) ~?(Q-':?Wisz.. Fax Number { 4~ B?~ -\'Zy (o '?-,
ARCHITECT OR El\'GNEER'S INFORMATION:
Name 6Amr-~ A 'P¥7 Ll c.~!
· Street Address -----------------City -------------~
State Zip Code ______ E-Mail Address --------------
Phone Number Fax Number ------------------------------
Application is hereby made for the follov,.1ng development specific site/waterway alterations:
l:?<V!tNA&e-l Y\t\'h?t>>J Pc!!Mtf'i:> 'foL ~1s-r1 "~ t>E-rQ-n1~ fAf.11...\'T:r oF-Lm ~
"=at f"C..ffi.\f\\[~ tNf?L>1\J\2t ~N' :re ~yv\Be'( °€-UNs:>ff .Pe.\:)-bu:.wt:=:. * :ra
ACKNOWLEDGME!"TS:
I, lbALI Sc.8oE.N~gBL. , design eRgiReei:.lowner, hereb y aclmowledge or affirm that:
The information and conclus ions contained in the above plans and supporting documents comply with the current
requirements of the City of College Station, Texas City Code, Chapter 13 and its associated Drainage Policy and Design
Standards .
As a condit ion of appro\'al of this pem1it application , I agree to construct the improvements proposed in this application
according to these documen ts and the requirements of Chapter 13 of the College Station City Code.
Property O\mer(s)
DEVELOP:>!E:---1 PE!Ud!T
DPER.J1.fff.DOC 3."2 4/99
Contractor
l of'.:
' .. DEC-10-1888 .;:-R I 03 : 42 PM CHAPPELL HI LL CO ~ST . FA X NO . 4098301363 P. 02
,.
10 /12 '99 16:19 F:\.X 409 693 4243 MD G ... ~~"'""
~lf FOR Of'FICE US.E ONLY
CASE NO.: DATE S'UBl'rt:IrIZO: ____ _
C'....Olflt,,t ~IAll(Jfll
DEVELOPMENT PERMIT
MINIMUM SUB:MITI'AL REQUIREMENTS
~ Sl00.00 Development Permit Application Fee.
_L Drainage and erosion control plan, 'With supporting Drainage Report two (2) copies each.
~Notice of Intent (N.O.I.) if disturbed area is greater than 5 acres.
APPLICANT (Primary Contact for the Project):
Name~ fYh:: .. :r~ (rtit>C:?i"'J
s~ A~s t9?1 :re")CAD A'1fl. ez, ~ b
Srau: }y_ Zip Code (7 ffi O
Phone Number b?°i ~-S'bsC)
city C.ourfl£. ~1aj
E-Mail Ad~s ~~ce. @ ~.(:c., ne,,t
FaxNwnbcr Ce't~-YZ.L.!Sz
PROPERTY O"WNER.'S INFORMATION:
Na.me lJJN.. -c Sc\o\e i;,..p.1'b::.f.V-( ~ "+«;;> l.JEAt?\NtaJ
Street Address :f'· Q, £?oze-. (og'L City _ ..... W?z ........ "'-F-..,~ ... -=-~ .... A=:w'\~-------
State JX.. Zip Code 7:7@.$'-i
Phone ~umber (t.\~') ~?w-?W.ez.
ARCHITECT OR ENOP.llEER'S INFORMATION:
Name 6nnii; f'R A 'P-..1> l.1 ~bci:T
· Street Address Ci'ty --------------
State Zip Code ------E-Mail Address ---~---------
Phone Number ------~----·Fax Number------------------
Application is hereby made for the follo"ving development specific site/waterway alterations:
J:::?tz>..1 NAO«= , ~'16Wll.N1~ ~L B\z'\\ "C5" ~"I~I ~ ~' \.. \1'1 eF U:n 1.,
:;a (,g&tn~ fN'f:,D1Y\t;?!sci' "Tc:. g!'..!.'\'lf.M?t g,~ @f?y;m2 ck= -rt)
ACKNO"WLEDGMEl\IS:
I. \Nb.i1..1 ~Qet=.l~'?L , dwe"g:: •R.sinS1Cr'owner, hereby acknowledge or affirm that;
The in.fortn2.tion a...-.,d conelusions contained in the ~bove plans and supporting documents c:omply \1.-=ith the current
requirements of the City of Colle£e St::it ion, Texas City Code, Chapter 13 :i..nd. its a.ss.ociated Drainage Polley and Design
Standards .
As. a condi ti on of ap;:iroval of th~·s P.el'T!"I · .:ippl icatior., I agree to construct the improvements proposed in this application
ac:cordlng to these docume ;ind e quirem~nts of Ch:ipter l3 of the CoUege Station City Code.
~) . ,,-r-WE1---------~---
Property Owner s) Contractor
OEVEWPMi::!\T PERMIT
OP'ER.MrT.DOC l/24/9S>
10/12 '99 16:48 TX/RX N0.9334 P.002 •
CERTIFICATIONS: (for proposed alterations within designated flood hazard areas .)
A. I, ~\\It b ,f?p.,-12...~u.. ;JQ. , certify that any nonresidential structure on or proposed to be on this site as part
of this application is designat ed to prevent damage to the structure or its contents as a result of flooding from the 100 year
~rG#J ,~ y,,.
Engineer
(/ Date
B . L Ntif.··rn Ez . "~ -:se. , certify that the finished floor elevation of the lowest floor, including any
basement, of any residential structu~e. proposed as part of this application is at or above the base flood elevation established
in the latest Federal Insurance Adminis ration Flood Hazard Study and maps, as amended.
6. h , tt9u 7J /tf f9
Date
C . L N/ A certify that the alterations or development covered by this permit shall not
diminish the flood-carrying capacity of the ·waterway adjoining or crossing this permitted site and that such alterations or
development are consistent v-ith requirements of the City of College Station City Code , Chapter 13 concerning
encroachments of flood.ways and of flood way fringes .
Engineer Date
D . I, N/A do certify that the proposed alterations do not raise the level of the 100 year
flood above elev ation established in the latest Federal Insurance Administration Flood Hazard Study.
Engineer Date
Conditions or comments as part of approval :----------------------------
In accordance , ... ;th Chap ter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure
that debris from construction , erosion, and sedimentation shall not be deposited in city streets , or existing drainage facilities .
All development shall be in accordance with the plans and specifications submitted to and approved by the City Engineer
for the above named proj ect. All of the applicable codes and ordinances of the City of College Station shall apply .
DE VEL OP~IE!'-1 PER.\IIT
DPERMIT.DOC 3.1 24 199
:? of2