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TEXCON GENERAL CONTRACTORS 19-Apr-02
CONSTRUCTION COST ESTIMATE
CASTLEGATE SUBDIVISION
COLLEGE STATION, TEXAS
SECTION 8 -30 LOTS
Item Estimated Unit Estimated
No. Description Quantity Price Cost
Sitework -PRIVATE
Mobilization/Layout 1.0 LS $6,000.00 $6,000
2 Site Preparation 2.0 AC $3,000.00 $6,000
3 Silt Fence 1,530 LF $2.50 $3,825
4 Construction Exit 1.0 LS $1,200.00 $1 ,200
5 Topsoil Stripping 1,000 CY $3.00 $3,000
6 Topsoil Replacement 500 CY $2.00 $1,000
7 Excavation/Grading 2,100 CY $3.50 $7,350
8 Lime Stabilized Subgrade -6" depth 5,780 SY $3.25 $18,785
9 Concrete Laydown Curb 2,165 LF $8.00 $17,320
10 Concrete 6" Standard Curb 890 LF $8.00 $7,120
11 Base Material -6" depth 5,000 SY $6.00 $30,000
12 Asphalt Paving - 1 1 /2" depth 5,000 SY $5.00 $25,000
13 Concrete Apron 2,720 SF $5.50 $14,960
14 Landscape Sleeves -2-4" PVC 140 LF $10.00 $1 ,400
15 Electrical Conduit -2-2" Gray PVC 25 LF $10.00 $250
16 Seeding & Hydromulch 3,300 SY $0.50 $1.650
Subtotal $144,860
Storm Drainage -PRIVATE
17 Drainage Pipe -24" RCP -structural 28 LF $45.00 $1 ,260
18 Drainage Pipe -24" RCP -non-structural 340 LF $36.00 $12,240
19 Inlets 5' wide 1 EA $2,400.00 $2,400
20 Inlets 10' wide 2 EA $3,200.00 $6,400
21 Headwall -24" RCP 2 EA $1 ,800.00 $3,600
22 Rock riprap 10 TN $50.00 $500
Subtotal $26,400
Water Lines
23 6" Water PVC CL200 (C900) structural 220 LF $26.00 $5,720
24 6" Water PVC CL200 (C900) non-structural 405 LF $18.00 $7,290
25 8" Water PVC CL200 (C900) structural 85 LF $30.00 $2,550
26 8" Water PVC CL200 (C900) non-structural 425 LF $20.00 $8,500
27 Connect to Existing Line 1 EA $200.00 $200
28 8" M.J. Bends -11 .25 deg. 2 EA $350.00 $700
29 6" M.J. Bends -22.50 deg. 4 EA $250.00 $1,000
30 6" M.J. Bends -45 deg. EA $250.00 $250
31 Gate Valves -6" 2 EA $500.00 $1,000
32 M.J. Tees -6" EA $275.00 $275
33 M.J. Tees -8" x 6" 2 EA $300.00 $600
34 M.J. Reducer -8" x 6" EA $250.00 $250
35 Water Services 17 EA $750.00 $12,750
36 2" Blow off Assembly 2 EA $450.00 $900
37 Fire Hydrant Assembly 2 EA $2,400.00 $4.800
Subtotal $46,785
Page 1 of 2
Sanitary Sewer Lines
38 6" SOR 26 Pipe -struct; avg depth 8'-10' 134 LF $31 .00 $4, 154
39 6" SOR 26 Pipe -non-str; avg depth 8'-10' 291 LF $21 .00 $6, 111
40 8" SOR 26 Pipe -non-str; avg depth 8'-10' 64 LF $22.00 $1,408
41 6" SOR 26 Pipe -struct; avg depth 10'-1 2' 78 LF $36.00 $2,808
42 6" SOR 26 Pipe -non-str; avg depth 10'-12' 156 LF $27.00 $4,212
43 8" SOR 26 Pipe -struct; avg depth 10'-12' 78 LF $37.00 $2,886
44 8" SOR 26 Pipe -non-str; avg depth 10'-12' 274 LF $26.00 $7, 124
44 6" ASTM-02241 -struct; avg depth 8-1 O' 20 LF $33.00 $660
45 6" ASTM-02241-struct; avg depth 10'-12' 20 LF $38.00 $760
46 Sewer Services 15 EA $750.00 $11 ,250
47 Manhole Drop 1 EA $900.00 $900
48 Tie-in to existing Manhole EA $500.00 $500
49 Manholes -average depth 8'-10' 4 EA $2,400.00 $9,600
50 Manholes -average depth 10'-12' 2 EA $2,600.00 $5,200
51 Manholes -average depth 12'-14' EA $2,800.00 $2,800
Subtotal $60,373
Total Sitework $144,860
Total Storm Drainage $26,400
Total Water $46,785
Total Sanitary Sewer 60 373
TOTAL CONSTRUCTION $278,418
Engineering and Survey @ 6% $16,705
Contingency @ 5% $13,921
TOTAL I $309,0441
f r-( 1 -D 2
Page 2 of 2
(f ~ DEVELOPMENT PERMIT
PERMIT NO. 02-16
Project: GARDENS OF CASTLEGATE
COLUGl STATION FOR AREAS OUTSIDE THE SPECIAL FLOOD HAZARD AREA
RE: CHAPTER 13 OF THE COLLEGE STATION CITY CODE
SITE LEGAL DESCRIPTION:
CASTLE GA TE SUBDIVISION
SECTION 8
DATE OF ISSUE: 5/24/02
OWNER:
GREENS PRAIRIE INVESTORS
5010 AUGUSTA CIRCLE
TYPE OF DEVELOPMENT:
SPECIAL CONDITIONS:
SITE ADDRESS:
CASTLEGATE DR
DRAINAGE BASIN:
Spring Creek
VALID FOR 12 MONTHS
CONTRACTOR:
TX CON
Full Development Permit
All construction must be in compliance with the approved construction plans
All trees must be barricaded, as shown on plans, prior to any construction. Any trees not barricaded will not
count towards landscaping points. Barricades must be 1' per caliper inch of the tree diameter.
Fill in the floodplain is not permitted on this project without an engineering study.
The Contractor shall take all necessary precautions to prevent silt and debris from leaving the immediate
construction site in accordance with the approved erosion control plan as well as the City of College Station
Drainage Policy and Design Criteria. If it is determined the prescribed erosion control measures are ineffective
to retain all sediment onsite, it is the contractors responsibility to implement measures that will meet City, State
and Federal requirements. The Owner and/or Contractor shall assure that all disturbed areas are sodden and
establishment of vegetation occurs prior to removal of any silt fencing or hay bales used for temporary erosion
control. The Owner and/or Contractor shall also insure that any disturbed vegetation be returned to its original
condition, placement and state. The Owner and/or Contractor shall be responsible for any damage to
adjacent properties, city streets or infrastructure due to heavy machinery and/or equipment as well as erosion,
siltation or sedimentation resulting from the permitted work.
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.
I hereby grant this permit for development of an area inside the special flood hazard area. All development
shall be in accordance with the plans and specifications submitted to and approved by the City Engineer in the
development permit application for the above named project and all of the codes and ordinances of the City of
College Stat); at apply. 'SJ CJ c..j ) ~
Da ( 4/.J~b z
Owner/Agent/Contractor Date
-· •• 't. ... -• ...... ,,
n-us FORM REPLACES PREVIOUS FOAM 3510-6 (8 -98)
See Reverse for Instructions
F0<m Approved. OMS No. 204<>-0 16
NP DES
FORM OEPA
Uniled S1a1os Environmontal Protection Agency
Washington. DC 20460
Notice of Intent (NOi) for Storm Water Discharges A"oclatod with
CONSIBUCTION ACTIVITY Under a NPOES General Permit
Submission of this Notice al Intent constitutes notice that the party identified in Section I of this form intends lo be authorized by a NPOES permit issue<
1or storm water discharges associated with construction ae1ivily in tho Statallndian Country land identified in Section II al this lorm. &omission al this NOlb
al Intent also constitutes notice that tho party identified in See1ion I of this lorm moots the eligibllily requirements in Part 1.B. al the general permit (indudifll
those related to prQ(oction al endangered species determined through the procedures in Addendum A al the general permit). understands that continue<
authorization to discharge Is cootingenl on maintaining permit eligibilily. and that implementation al the Slorm Water Pollution Pr01190tion Plan required undo
Part IV al the general permit will begin at the time the permittoo commences worlc on the coostruction project identified in Secion II below. IN ORDER TC
OBTAIN AUTHORIZATION. ALL INFORMATION REQUESTED MUST BE INCLUDED ON THIS FORM_ SEE INSTRUCTIONS ON BACK OF FORM
I. Owner/Operlll<>< (Applicant) Information
Name: l;~(P.IC 1c 1n1.l1 ,Ar,q_,,· ,r, ··1e1 Phone:
Address: I fi 0 I I I 0 I I A-1 q I j I u I .S I t, «I
Cily: 1C.101l1l1L1jlC'I ,Si+1t:t1f11 I O I"-I I I I I I I l State: rrJ.l:J I I
11_ Project/Site lnfonnatlon Is the facility located on Indian
Country Lands?
P<a;od ... moo i!'.'.1• 1'.i1h I 1~1Q'+1< I ,s,.,b, J, .. ,., i I J,,· ,. ,. , I I I I I I I I y., 0 No [ij
Projee1Addressllocation:IN1 101 I 1{,1r1~1e1"151 1P1r14111r1:1('1 1~d1 1l1 .1D1 tMlJ 1u11,,,fff{f:,
City: "1oilil1~1~1e1 1Srbo.i+1; ,, l"'-1 I I I I I I I I Stale: LZ1x.J ZipCode: 1?171Bifi51 -1 I I I
LaMude:l310IJ11101ul Longitude: I 111bl f1blJ10l County:l8'1f1Q1Z.101j1 I I I I I I I I I I I I
Has the Storm Water Pollution Prevention Plan (SWPPP) been prepared? Yes ~ No 0
Optional: Address al location al
SWPPP lor viewing ~ress on See1ion I above 0 Address in Section II above 0 Other address (ii known) below:
SWPPP Phone:
Address: I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I
City: I I I I I I I I I I I I I I I I I I I I I I I State: LLJ ZipCode: l._~l.__l.__l.__l.__.._1-~l__._1__._l~I -
Name ol Receiving Water: 1 .... f.....Lj, P'-'--' r__.._, ,_·Lei O:..L.Llj_,_,_I __._1<;__.__r_.1_<= ..... 1_-C_.1w.fc_.1.__1.__.._1 _._I _._I __._I __._I __._I __..I __.1__.l__...J__,I
o~
19'D1l161 z, o, 01 ol 1 lt}1310 I y o,o ii I
Month Day )!oar Month 0.ty l'llar
Estimated Construction Start Date Estimated Completion Date
Estimate ol area lo be disturbed (lo nearest acre): I I I I I Z151
Estimate al Likelihood al Discharge (choose only one):
1. 0 Unlikely 3. [!'.:]""Once pe1 week 5. 0 Contonual
2. 0 Once per month 4. 0 Once per day
111. Certification
Based on inslrue1ion provided in Addendum A ol the permit. are
there any ~sled endangered or threatened speoes. or designate<
critical habitat in lhe project area?
Yes 0 No QJ'"
I haw satisfied permit eligl>ilily with regard 10 prOlection al
endangered species through the indicated section al Part t.8.3.e.(2
al the permit (chedc one or more boxas):
(a) (Ll/(b) 0 ic>O (d>O
I conity under penally of law lhal this document and all anachments wore prepared under my diree1ion or supervision on accordance with a syston
designed to assure that quatilied personnel properly galher and evaluate lhe onformalion subm1ned. Based on my inQuiry al the person or persons w h<
manage !his system. or those persons directly responsible lor galhering the information. the information sut>mined is. lo the best al my knowledge an<
belief. true. accurate. and complete I am aware rhdt rhere are s19notoean1 penalties lor submitting false information. including lhe pos.s1b1ti1y of tine a0<
ompcisonment tor knowing violations
I I Date l o J 1IL11 I 01 C-I
f-PA. Form )510·9 roplacod JSI0-6 (6·96)
TEX CON
General Contractors
Div. of CDS Enterprises, Inc.
c(, {1t/O 2-
l :01 p1'Y'
82-~
1 5
1707 Graham Rd. • College Station, TX 77845 • 979-690-7711 • Fax: 979-690-9797
May 13 , 2002
Bridgette George
Asst. Development Coordinator
City of College Station
1101 Texas Avenue South
College Station, TX 77842
RE: Development Permit
Castlegate Subdivision, Section 8 -The Gardens of Castlegate
College Station, Texas
Dear Ms. George:
Attached are five (5) copies of the revised construction documents and one copy of the
completed Notice of Intent (NOI) form. Please approve and return the two extra sets of
construction documents for use by our office. The NOI attached covers the entire
Castlegate Subdivision Development.
If you have any questions or need additional information, please do not hesitate to give
me a call at (979) 690-7711.
Sincerely Yours,
Joe Schultz, P .E.
Engineering Manager
Attachments
STAFF REVIEW COMMENTS NO. 1
Project: DP-GARDENS OF CASTLEGATE-DEVELOPMENT PERMIT (02-00100016)
ENGINEERING
1. Sheet 9, Details 3-E and 3-G. Please show that service lines are to meet ASTM
2241 and use SOR 21 or SCH 40 pipe in accordance with S. 203.5. C.1. City Specs.
2. Please present copy of NOi for this project for Development Permit.
3. Drainage Report approved.
Reviewed by: Spencer Thompson Date: May 9, 2002
NOTE: Any changes made to the plans, that have not been requested by the City of College Station, must be explained in your
next transmittal letter and "bubbled" on your plans. Any additional changes on these plans that have not been pointed out
to the City, will constitute a completely new review.
Page 2 of 2
ro_-00 lOOOl(p
P&Z CASE NO.:
{Check one) Minor __ Amending
($300.00)
VFinal
($400.00)
__ Vacating __ Replat
($300.00) ($400.00) ($400.00)
The following items must be submitted by an established filing deadline date for P&Z Commission consideration.
MINIMUM SUBMITTAL REQUIREMENTS:
/Filing Fee (see above) NOTE: Multiple Sheets -$55.00 per additional sheet
~ Development Permit Application Fee of $200.00 (if applicable).
· ~ Infrastructure Inspection Fee of $600.00 (applicable if any public infrastructure is being constructed.).
·./ Application completed in full.
v Thirteen (13) folded copies of plat. (A signed mylar original must be submitted after staff review.)
~ One (1) copy of the approved Preliminary Plat and/or one (1) Master Plan (if applicable).
~ Paid tax certificates from City of College Station, Brazos County and College Station l.S.D.
__L_ A copy of the attached checklist with all items checked off or a brief explanation as to why they are not.
_L Two (2) copies of public infrastructure plans associated with this plat (if applicable).
~ Parkland Dedication requirement approved by the Pa rks & Recreation Board, please provide proof of
approval (if applicable).
NAME OF suB01v1s10N Ca s-He.tjtb, Subdiv1'Si1Z11---Sed-. 61"1l:e.. GMdetls of CAsfu~~
SPECIFIED LOCATION OF PROPOSED SUBDIVISION lJ€.St of S-1P----\-e. th~kwJ~ ("
DV\ Gw--.eg_y\s %rur-LL k_oo..d
APPLICANT/PROJECT MANAGER'S INFORMATION (Primary Contact for the Project):
Name Grei'.Jl\S ftc'.l.l'I ~ :JYJveSto\CS Lt-J , -w<llaLZJ?vullip$
Street ~ress 444 0 (a sf:l.w,~ 1Jci Ii~ City Co ((evy' 5J-ali 'e-vt.
State \ !-Zip Code -:1_19ifl:S:_ E-Mail Address ___________ _
Phone Number {oCf 3 -J<Q ?o Fa x Number --""'[Q'--qL...:O=-----l,_4J......\?.2...::.JO~-----
PROPERTY OWNER'S INFORMATION:
Name fucu.YJ ~ \)r-q) rU.. ~ ve.s-fur-~ LtJ .
Street Address Lt-A-qo CttS~qJ:i, Jay)\ Vf City Colle<:Je St~DYl
Sta te \'}. Zip Code 11'fitc;:-E-Mail Address ___________ _
Phone Number 04 ~ -I Cb20 Fa x Number ____ l:z"-1~0~-~l _%""'--'-=O~-----
ARCHITECT OR ENGINEER'S INFORMATION:
Name , \Qe Sc\l\u \h 1 }?,8 . -~CD vi Gevier~ Covdr~s
Street Address \ 10] l?Jv-11.,ho..w\ J?__oe,j City ~_5fuiitnd -
State :fX Zip Code 11~4-\ E-Mail Address joe-SlJ\:/i&EJ ~~;ov;:, 11\e.f-
Phone Number (/10-11 I \ Fa x Number _ ..... lo'-C(J.....::0'----'-1_._11~1 _____ _
FNLPAPP.DOC 4/17/02 1 of 3
fR_t VAT"f:-
Total Acres Of Subdivision Cf· L2(e tlC-R-0-W Acreage /, 11j ~ Total# Of Lots _?a ___ _
Number Of Lots By Zoning District 32 I fDP -H I / __ _
Average Acreage Of Each Residential Lot By Zoning District:
D.12 I fVv-H I I ---
Floodplain Acreage Q. 5W {).(___,
A Statement Addressing Any Differences Between The Final Plat And Approved Master Development Plan
And/Or Preliminary Plat (If Applicable):
Acx<-!Mf clttt4Y'f cl ft1DY1 IZ ·DI a&. &Y\ n1a.ster ]tdlW\ BJ. :It> Cf _ 7-Zk a£.
Requested Variances To Subdivision Regulations & Reason For Same: ~ fQ2-i-l Cf211l.CQff f?Uvi ·.
r~~utzJe£l Y'-Owk~·ozbm: Jo ~fil pVwlt w~ci#i1 '&ideviall ~~LJ-fr~m~1 bu i i~~
tllstOS)lQ,,S1 Lot ?file-~ dimrn~t0111S, ~ Uhick i ml\-sfi'd pzvhsg -
Requested Oversize Participation: ~~~----------------------
Total Linear Footage of
Proposed Public:
\34-l 1 Streets
0 Sidewalks
ins' Sanitary Sewer Lines
\\~1· Water Lines
0 Channels
,
':3</0 Storm Sewers
0 Bike Lanes I Paths
Parkland Dedication due prior to filing the Final Plat:
ACREAGE:
___ #of acres to be dedicated + $ ___ development fee
___ # of acres in floodplain
# of acres in detention --
__ #of acres in greenways
OR
FEE IN LIEU OF LAND:
___ #of Sin gle-Family Dwelling Un its X $457 = $ ___ _
______ (date) Approved by Parks & Re creation Board
NOTE: DIGITAL COPY OF PLAT MUST BE SUBMITTED PR IOR TO FILING.
The applicant has prepared this application and certifies that the facts stated herein and exhibits attached
hereto are true, correct and complete. The undersigned hereby requests approval by the City of College
Station of the above-identified final plat.
~ .. / .. LLea-~ ~~ Signature and TitlB ~ / . Date
FNLPAPP.DOC 4/17/02 2 of 3
SUPPLEMENTAL DEVELOPMENT PERMIT INFORMATION
ACKNOWLEDGMENTS:
I, __ \J_l\...,_\~\~t.AL~_e.... __ 'f\1'--_t_-~l l~i'+p-S~----' design engineer/owner. hereby acknowledge or affirm that:
The information and conclusions contained in the above plans and supporting documents comply with the current
requirements of the City of College Station, Texas City Code, Chapter 13 and its associated Drainage Policy and Design
Standards. As a condition of approval of this permit application, I agree to construct the improvements proposed in this
ap~~rJkn o· es documents and the requirements of Chapter 13 of the College Station City Code.
G.11, E/IJ.S
Property Owner( s) Contractor
CERTIFICATIONS: (for proposed alterations within designated flood hazard areas.)
A.I, certify that any nonresidential structure on or proposed to be on this site
as part of this application is designated to prevent damage to the structure or its contents as a result of flooding from the
100 year storm.
Engineer Date
B. I, certify that the finished floor elevation of the lowest floor, including any
basement, of any residential structure, proposed as part of this application is at or above the base flood elevation
established in the latest Federal Insurance Administration Flood Hazard Study and maps, as amended.
Conditions or comments as part of approval: ___________________________ _
In accordance with Chapter 13 of the Code of Ordinances of the City of College Station, measures shall be taken to insure
that debris from construction, erosion, and sedimentation shall not be deposited in city streets, or existing drainage
facilities. All development shall be in accordance with the plans and specifications submitted to and approve d by the_ City
Engineer for the above nam ed project. All of the applicable codes and ordinances of the City of College Station shall
apply.
FNLPAPP.DOC 4/17/02 3 of 3
Drainage Report
for
Castlegate Subdivision
Section 8
College Station, Texas
April 2002
Developer:
Greens Prairie Investors, Ltd.
By Greens Prairie Associates, LLC
4490 Castlegate Drive
College Station, Texas 77845
(979) 690-7250
Prepared By:
TEXCON General Contractors
1707 Graham Road
College Station, Texas 77845
(979) 690-7711
CERTIFICATION
I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this
report for the drainage design for the Castlegate Subdivision -Section 8, was prepared by me
in accordance with the provisions of the City of College Station Drainage Policy and Design
Standards for the owners hereof.
_ .... ~""-'"'>i.~,
--'\E OF t \' ;" 'r ••••••••••• ~-+-'• ~ 0 •• •· * ··.:<S' •• "* .. ·. * ... ~... ·.*~ ~···································~ "I. JOSEPH P. SCHULTZ l ~···································~ ,~··. 65889 .:ttJ
'• 0-<-:'~fo ~~.·~4.i ~ •,~n ·· ISTE.~·· 0, .,
' 'JS •••••••• ~ ,. \\\:10NAL ~--,,~-
f-19-0Z
MA'< 1 0 2002
GE STATION CO~if"GINEERING
TABLE OF CONTENTS
DRAINAGE REPORT
CASTLEGATE SUBDIVISION -SECTION 8
CERTIFICATION ................................................................................................................................................................. 1
TABLE OF CONTENTS ....................................................................................................................................................... 2
LIST OF TABLES .................................................................................................................................................................. 2
INTRODUCTION .................................................................................................................................................................. 3
GENERAL LOCATION AND DESCRIPTION ................................................................................................................. 3
FLOOD HAZARD INFORMATION ................................................................................................................................... 3
DEVELOPMENT DRAINAGE PATTERNS ...................................................................................................................... 3
DRAIN AGE DESIGN CRITERIA ....................................................................................................................................... 3
STORM WATER RUNOFF DETERMINATION .............................................................................................................. 4
DETENTION FACILITY DESIGN ..................................................................................................................................... 5
STORM SEWER DESIGN .................................................................................................................................................... 5
CONCLUSIONS ..................................................................................................................................................................... 6
APPENDIX A ......................................................................................................................................................................... 7
Storm Sewer Inlet Design Calculations
APPENDIXB .......................................................................................................................................................................... 9
Storm Sewer Pipe Design Calculations
EXllIBIT A ........................................................................................................................................................................... 15
Of/site Infrastructure Plan for Castlegate Subdivision
EXJIIBIT B ........................................................................................................................................................................... 17
Post-Development Drainage Area Map
LIST OF TABLES
TABLE 1 -Rainfall Intensity Calculations .............................................................................................. 4
TABLE 2 -Post-Development Runoff Information -Storm Sewer Design ........................................... 5
2
DRAINAGE REPORT
CASTLEGATE SUBDIVISION -SECTION 8
INTRODUCTION
The purpose of this report is to provide the hydrological effects of the construction of the
Castlegate Subdivision -Section 8, and to verify that the proposed storm drainage system
meets the requirements set forth by the City of College Station Drainage Policy and Design
Standards.
GENERAL LOCATION AND DESCRIPTION
The project is located on a portion of a 111.46 acre tract located west of State Highway 6 along
the north side of Greens Prairie Road in College Station, Texas. This report addresses Section
8 of this subdivision, which is made up of 9.226 acres. The site is wooded with the vegetation
primarily consisting of oak trees and yaupons. The existing ground elevations range from
elevation 300 to elevation 312. The general location of the project site is shown on the vicinity
map in Exhibit B.
FLOOD HAZARD INFORMATION
The project site is located in the Spring Creek branch of the Lick Creek Drainage Basin. The
site is located in a Zone X Area and in a Zone AE Area according to the Flood Insurance Rate
Map prepared by the Federal Emergency Management Agency (FEMA) for Brazos County,
Texas and incorporated areas dated February 9, 2000, panel number 48041C0205-D. Zone X
Areas are determined to be outside of the 500-year floodplain. Zone AE Areas are inundated
by the 100-year floodplain, and base flood elevations have been determined. These elevations
are shown on Exhibit B.
DEVELOPMENT DRAINAGE PATTERNS
This section is situated in such a way that prior to development, the storm water runoff flows
north, east and west into the adjacent tributaries of Spring Creek. Ultimately, the runoff flows
into Spring Creek and then to the proposed regional detention facility. Refer to the Offsite
Infrastructure Plan in Exhibit A for the location of this proposed detention facility.
DRAINAGE DESIGN CRITERIA
The design parameters for the storm sewer are as follows:
• The Rational Method is utilized to determine peak storm water runoff rates for the stom1
sewer design.
• Design Stom1 Frequency
Storm Sewer system 10 and 100-year storm events
3
• Runoff Coefficients
Post-development (patio homes) c = 0.65
• Rainfall Intensity values for Brazos County for a minimum time of concentration of 10
minutes can be found in Table 1. Where a longer time of concentration was necessary, it is
noted in the respective table, and the intensities are calculated with the higher values where
required.
• Time of Concentration, tc -Due to the small sizes of the drainage areas, the calculated
times of concentration, tc, are less than 10 minutes. Therefore, a minimum tc of 10 minutes
is used in most cases to determine the rainfall intensity values. Where a longer time of
concentration was necessary, it is noted and used accordingly.
STORM WATER RUNOFF DETERMINATION
The peak runoff values were determined in accordance with the criteria presented in the
previous section for the 5, 10, 25 , 50, and 100-year storm events. The runoff coefficients are
based on the future development of this tract. Exhibit B shows the post-development drainage
areas for the storm sewer design. Post-development runoff conditions for the storm sewer
design are summarized in Table 2.
TABLE 1 -Rainfall Intensity Calculations
Rainfall Intensity Values (in/hr)
Storm t.:=
Event 10 min
Is 7.693
110 8.635
l2s 9.861
lso 11 .148
1100 11 .639
Brazos County:
5 year storm 1 O year storm
b = 76 b = 80
d = 8.5 d = 8.5
e = 0.785 e = 0.763
I = b I (tc+d)e
I = Rainfall Intensity (in/hr)
tc = U(V*60)
tc = Time of concentration (min)
L = Length (ft)
V = Velocity (ft/sec)
25 year storm 50 year storm 100 year storm
b = 89 b = 98 b = 96
d = 8.5 d = 8.5 d = 8.0
e = 0.754 e = 0.745 e = 0.730
(Data taken from State Department of Highwavs and Public Transportation Hydraulic Manual, page 2-16)
4
TABLE 2 -Post-Development Runoff Information -Storm Sewer Design
Area c 5 year storm 10 year storm 25 year storm 50 year storm 100 year storm tc Area# (acres) Is Os 110 0 10 l2s 02s lso Oso 1100 C1 C2 Crotal A, A2 Total (min) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr) (cfs) (in/hr)
1 1.15 0 1.15 0.65 0.3 0.65 10 7.693 5.75 8.635 6.45 9.861 7.37 11.148 8.33 11.639
2 0.79 0 0.79 0.65 0.3 0.65 10 7.693 3.95 8.635 4.43 9.861 5.06 11 .148 5.72 11.639
3 1.13 0 1.13 0.65 0.3 0.65 10 7.693 5.65 8.635 6.34 9.861 7.24 11 .148 8.19 11.639
4 0.17 0 0.17 0.65 0.3 0.65 10 7.693 0.85 8.635 0.95 9.861 1.09 11 .148 1.23 11 .639
5 0.56 0 0.56 0.65 0.3 0.65 10 7.693 2.80 8.635 3.14 9.861 3.59 11 .148 4.06 11 .639
6 0.55 0 0.55 0.65 0.3 0.65 10 7.693 2.75 8.635 3.09 9.861 3.53 11 .148 3.99 11 .639
The Rational Method:
Q=CIA I = b I (ic+d)0
Q = Flow (cfs)
A= Area (acres)
C = Runoff Coeff.
tc =Time of concentration (min)
tc = L/(V*60)
L = Length (ft
V =Velocity (ft/sec)
I = Rainfall Intensity (in/hr)
Brazos County:
5 i'.ear storm 10 i'.ear storm 25 i'.ear storm 50 i'.ear storm 100 i'.ear storm
b = 76 b = 80 b = 89 b = 98 b = 96
d = 8.5 d = 8.5 d = 8.5 d = 8.5 d = 8.0
e = 0.79 e = 0.76 e = 0.75 e = 0.745 e = 0.730
DETENTION FACILITY DESIGN
The detention facility handling the runoff from this site will be a regional facility designed by
LJA Engineering & Surveying, Inc. Refer to the Offsite Infrastructure Plan in Exhibit A for the
location of this proposed detention facility. The runoff from this project flows into existing
drainages and then into Spring Creek. The detention facility is located adjacent to Spring
Creek prior to Spring Creek entering the State Highway 6 right-of-way.
STORM SEWER DESIGN
The storm sewer piping for this project has been selected to be Reinforced Concrete Pipe
(RCP) meeting the requirements of ASTM C-76, Class III pipe. The curb inlets will be cast-in-
place concrete.
Appendix A presents a summary of the storm sewer inlet design parameters and calculations.
The inlets were designed based on a 10-year design storm. As per College Station guidelines,
the capacities of inlets in sump were reduced by 10% to allow for clogging.
Inlets for the residential streets were located to maintain a gutter flow depth of 5" or less. This
design depth will prevent the spread of water from reaching the crown of the road for the 10-
year storm event. The runoff intercepted by the proposed storm sewer inlets was calculated
using the following equations. The depth of flow in the gutter was determined by using the
Straight Crown Flow equation. The capacities for the inlets in sumps (Inlets 1, 2 & 3) were
calculated using the Inlets in Sumps, Weir Flow equation with a maximum allowable depth of
5
0100
(cfs)
8.70
5.98
8.55
1.29
4.24
4.16
7" (5" gutter flow plus 2" gutter depression). These equations and the resulting data are
summarized in Appendix A.
Appendix B presents a summary of the storm sewer pipe design parameters and calculations.
All pipes are 24" in diameter for this development. For these pipes, the cross-sectional area is
reduced by 25 %, as per College Station requirements. A summary of how this was achieved is
shown in Appendix B as well. The pipes for the storm sewer system were designed based on
the 10-year storm event, and they will also pass the 100-year storm event without any
headwater. Based on the depth of flow in the street determined for the 100-year storm event,
this runoff will be contained within the street right-of-way until it enters the storm sewer
system. As required by College Station, the velocity of flow in the storm sewer pipe system is
not lower than 2.5 feet per second, and it does not exceed 15 feet per second. As the data
shows, even during low flow conditions, the velocity in the pipes will exceed 2.5 feet per
second and prevent sediment build-up in the pipes. The maximum flow in the storm sewer pipe
system will occur in Pipe No. 2. The maximum velocity for the pipe system in this
development will be 10.1 feet per second and will occur in Pipe No. 2. Appendix B contains a
summary of the Manning pipe calculations as well as flow diagrams mapping the flows through
the storm sewer system for the 10 and 100-year events.
CONCLUSIONS
The construction of this project will significantly increase the storm water runoff from this site.
The proposed storm sewer system should adequately control the runoff and release it into
existing drainages. Also, the regional detention facility should adequately reduce the peak
post-development runoff to less than the pre-development runoff for the design storm event.
This will prevent any impact on the properties downstream of this project.
6
APPENDIX A
Storm Sewer Inlet Design Calculations
7
Castlegate Subdivision -Section 8
Inlet Length Calculations
Inlets In Sump
Inlet# Length & Type Flow from A c 0 10 Qcarryover
Area# (acres) (cfs) (cfs) from inlet#
1
2
3
1 O' Recessed 1 1.15 0.65 6.45 0
6 0.55 0.65 3.09 0
4 0.17 0.65 0.95 0 5' Recessed --5 0.56 0.65 3.14 0
1 O' Recessed 2 0.79 0.65 4.43 0
3 1.13 0.65 6.34 0
Transverse (Crown) slope (ft/ft) = 0.0315
Straight Crown Flow (Solved to find actual depth of flow, yl:
Q = 0.56 • (z/n) * s ''2 * ys13 c:> y ={QI (0.56 * (z/n) • s "2]}31s
n = Roughness Coefficient = 0.018
z = Reciprocal of crown slope =
S = StreeUGutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
32
-
-
-
-
-
10 year storm
QTotal Q Total+10% Y10-actual
(cfs) (cfs) (ft) (in)
6.45 7.10 0.300 3.61
3.09 3.40 0.228 2.73
0.95 1.05 0.147 1.76
3.14 3.46 0.229 2.75
4.43 4.88 0.261 3.13
6.34 6.98 0.299 3.58
Inlets in sumps, Weir Flow:
L = Q I (3 * y312) ¢ y = (Q I 3L)v3
L = Length of inlet opening (ft)
Q = Flow at inlet (cfs)
y = total depth of flow on inlet (ft)
max y for inlet in sump = 7" = 0.583'
100 year storm
L10..Req'd* L10-actual 0 100 Qcarryover Orotal Orota.-+10%
(ft) (ft) (cfs) (cfs) from inlet# (cfs) (cfs)
8.70 0 -8.70 9.57 7.86 10 4.16 0 -4.16 4.58
1.29 0 1.29 1.41 3.37 5 4.24 0 -4.24 4.66
5.98 0 5.98 6.57 8.88 10 8.55 0 -8.55 9.40
*using Ymu = 7" = 0.583'
Capacity of Inlets on grade:
Qc = 0.7 * [1/(H1-H2)) * (H1
512-H2512]
Oc = Flow capacity of inlet (cfs)
H1 =a + y
H2 = a =gutter depression (2" Standard; 4" Recessed)
y = Depth of flow in approach gutter (ft)
Y100
(ft) (In)
0.606 7.27
0.547 6.57
0.657 7.88
APPENDIXB
Storm Sewer Pipe Design Calculations
9
Castlegate Subdivision
Pipe Calculations -Section 8
Inlet Invert Outlet Invert 1 O year storm 100 year storm
Pipe# Size Length Slope Elev Elev *Actual Flow Design Flow v,, Travel Time, Ina *Actual Flow Design Flow V100 % Full
(in) (ft) (%) (ft) (ft) (els) (els) (fps) (sec) (min) (els) (els) (fps)
1 24 27.7 1.20 304.20 303.87 9.54 15.41 7.8 59.9 4 0.06 12.86 20.77 8.3
2 24 160.8 1.80 303.75 300.90 13.63 22.01 9.9 66.5 16 0.27 18.39 29.70 10.1
3 24 178.2 1.10 300.80 298.85 10.77 17.39 7.8 67.0 23 0.38 14.53 23.47 7.9
*These values reflect the actual flow for the 24" pipes. The design flow for these pipe sizes reflects a 25% reduction in pipe area.
(Refer to attached calculation for specific information.)
% Full
74.3
87.9
89.9
Travel Time, tnoo
(sec) (min)
3 0.06
16 0.27
23 0.38
City of College Station requirement to Reduce Cross-Sectional Area of 18" & 24" Pipes by 25%
Using Mannings Equation from page 48 of the College Station Drainage Policy & Design Standards Manual:
Q = 1.49/n * A * R213 * S 112
Q = Flow Capacity (cfs)
18" Pipe:
Pipe size (inches) =
Wetted Perimeter WP, (ft) =
Cross-Sectional Area A, (ft2) =
Reduced Area AR, (ft2) =
Hydraulic Radius R =A/WP, (ft) =
Reduced Hydr Radius RR = AR/Wp, (ft) =
Roughness Coefficient n =
Friction Slope of Conduit Sf, (ft/ft) =
Example Calculation:
Slope Flow Capacity Reduced Flow Capacity
s Q
0.005 6.91
0.006 7.57
0.007 8.18
24" Pipe:
Pipe size (inches) =
Wetted Perimeter WP, (ft) =
Cross-Sectional Area A, (ft2) =
Reduced Area AR, (ft2) =
Oreduced
4.28
4.69
5.06
Hydraulic Radius R =A/WP, (ft) =
Reduced Hydr Radius RR = AR/Wp, (ft) =
Roughness Coefficient n =
Friction Slope of Conduit Sf, (ft/ft) =
Example Calculation:
Slope Flow Capacity Reduced Flow Capacity
s Q Oreduced
0.005 14.89 9.22
0.006 16.31 10.1
0.007 17.61 10.9
Conclusion:
18
4.71
1.766
1.325
0.375
0.281
0.014
0.01
% Difference
OreduceiQ
0.619
0.619
0.619
24
6.28
3.14
2.355
0.5
0.375
0.014
0.01
% Difference
Oreducei Q
0.619
0.619
0.619
Multiply actual Q in 18" & 24" pipes by 1.615 to reflect a 25% reduction in the
cross-sectional area called for on page 47, paragraph 5 of the College Station
Drainage Policy & Design Standards manual.
Pipe 1 -10 Year Storm
Manning Pipe Calculator
Given Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning's n .................... .
Computed Results :
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
24.0000 in
15.4100 cfs
0 .0120 ft/ft
0. 0140
14 .3696 in
3 .1416 ft2
1.9631 ft2
42.4696 in
75.3982 in
7.8497 fps
6.6563 in
59.8731 %
23.0115 cfs
7.3248 fps
Pipe 1 -100 Year Storm
Manning Pipe Calcu lat or
Given Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning ' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocit y ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Castlegate Subdivision -Section 8
College Station, Texas
Circular
Depth of Flow
24.0000 in
20.7700 cfs
0.0120 ft/ft
0. 0140
17.8435 in
3.1416 ft2
2.5047 ft2
49 .9057 in
75.3982 in
8 .2923 fps
7 .2272 in
74.3481 %
23.0115 cfs
7 .3248 fps
Pipe 2 -10 Year Storm
Manning Pipe Calculator
Given Input Data:
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocit y ....................... .
Hydraulic Radius ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow velocity ............. .
Circular
Depth of Flow
24.0000 in
22.0100 cfs
0.0180 ft/ft
0. 0140
15.9572 in
3.1416 ft2
2.2182 ft2
45 .7644 in
75.3982 in
9.9226 fps
6.9796 in
66 .4882 %
28.1832 cfs
8 .9710 fps
Pipe 2 -100 Year Storm
Manning Pipe Calculator
Given Input Data :
Shape .......................... .
Solving for .................... .
Diameter ....................... .
Flowrate ....................... .
Slope .......................... .
Manning ' s n .................... .
Computed Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimeter ............... .
Perimeter ...................... .
Velocity ....................... .
Hydraulic Radius ............... .
Percent Full ................ : .. .
Full flow Flowrate ............. .
Full flow v elocity ............. .
Castlegate Subdivision -Section 8
College Station, Texas
Circular
Depth of Flow
24.0000 in
29.7000 cfs
0.0180 ft/ft
0.0140
21 .1066 in
3.1416 ft2
2.9266 ft2
58 .3775 in
75.3982 in
10.1483 fps
7.2191 in
87 .9442 %
28.1832 cfs
8 .9710 fps
Pipe 3 -10 Year Storm
Manning Pipe Calcul ator
Giv en Input Data:
Shape .......................... .
Solv ing for .................... .
Diameter ....................... .
Flowrat e ....................... .
Slope .......................... .
Manning ' s n .................... .
Comp uted Results:
Depth .......................... .
Area ........................... .
Wetted Area .................... .
Wetted Perimet er ............... .
Per i meter ...................... .
Velocity ....................... .
Hydrau lic Radiu s ............... .
Percent Full ................... .
Full flow Flowrate ............. .
Full flow v e l ocity ............. .
Circular
Depth of Flow
24.00 0 0 in
17 .3900 cfs
0 .0110 ft /ft
0 . 0140
16.0799 in
3 .1416 ft 2
2.2374 ft2
46 .0249 in
75 .3982 in
7.7723 fps
7.0004 i n
66 .9996 %
2 2 .0318 cfs
7.0129 fps
Pipe 3 -100 Year St orm
Manning Pipe Calcu lator
Giv en Input Data:
Shape .......................... .
Solving for .................... .
Diamet er ....................... .
Flowrat e ....................... .
Slope .......................... .
Manning ' s n .................... .
Computed Results :
Depth .......................... .
Area ........................... .
Wetted Area ............. : ...... .
Wetted Peri meter ............... .
Perimeter ...................... .
Velocity ....................... .
Hy draul i c Radius ............... .
Per cent Full ................... .
Full flow Flowrate ............. .
Ful l f low veloci t y ............. .
Castlegate Subdivision -Section 8
College Station, Texas
Circu lar
Depth of Flow
24 .0000 i n
23.4700 cfs
0. 0110 ft/ft
0.0140
21.5745 i n
3.1416 f t 2
2 .9755 ft2
59 .8693 in
75 .3982 i n
7 .8877 fps
7.1569 i n
89 .8937 %
22.0318 c f s
7 .0129 f ps
EXHIBIT A
Offsite Infrastructure Plan for Castlegate Subdivision
15
EXHIBIT B
Post-Development Drainage Area Map
17