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Drainage Report — Executive Summary
Spring Creek Townhomes, Phase 3
College Station, Texas
ENGINEER
SCHULTZ ENGINEERING, LLC.
P.O. Box 11995
College Station, Texas 77842
Phone: (979) 764-3900
Fax: (979) 764-3910
Spring Creek CS Development, Ltd.
3302 General Parkway
College Station, TX 77845
Phone: (979) 690-5000
GENERAL DESCRIPTION AND LOCATION
This project consists of the development of Phase 3 of the Spring Creek Townhomes Subdivision in College Station,
which is a single-family residential development, which will include the construction of utilities and infrastructure
Location: Phase 3 is located between Decatur Drive and Spring Hill Drive, adjacent to
Phase 1 of the Spring Creek Gardens development and south of the Spring
Creek Townhomes Phase 2 development. The entire site lies within the
corporate limits of the City of College Station.
Description
• Area: 5.309 Acres
• Proposed Land Use: Single Family Residential
• #of Lots: 42lots
• Existing Land Use: Vacant
• Land Description: The terrain slopes generally towards the south.
Primary Drainage Facility: Tributary A of Spring Creek
Flood Hazard Information:
FEMA FIRM. #48041C0310E & #48041C0325E, Dated May 16, 2012
Floodplain: None of this phase of the development lies within the floodplain.
HYDROLOGIC CHARACTERISTICS
The existing site is open area. The elevations range from 270 to 286, sloping in a southerly direction, where
runoff enters Tributary A of Spring Creek, which ultimately flows into Spring Creek. A detention pond
was constructed on the Crowley Tract, which is now the Tower Point Development, downstream of this
development to control the increase in runoff from this property.
The runoff from the development will be captured by the proposed and existing storm sewer system and
discharged into the storm sewer system for Decatur Drive, which is sized to handle all the developed
condition runoff from the development. The design of the storm system is in compliance with the drainage
report submitted with Phase 2 construction plans.
GENERAL STORMWATER PLAN
The drainage plan for this development will involve the installation of a pipe and inlet, which will collect
and transmit the runoff into the storm sewer system for Decafur Drive which flows into Tributary A of
Spring Creek. Phase 2 of Spring Creek Townhomes was designed to handle all the developed condition
runoff from Phase 3.
The detention pond for this proposed development is located in the Tower Point Development.
COORDINATION & STORMWATER PERMITTING
This project will have a Notice of Intent filed with the Texas Commission for Environmental Quality. No
other permits are anticipated for this project.
DRAINAGE DESIGN
General Information: Stormwater runoff from Phase 3 of the subdivision will be collected by a
proposed and existing storm sewer system. The location of the drainage areas
for evaluation of the gutter depth check, inlet sizing, pipe evaluation and channel
sizing are shown on Exhibit A & B. Refer to Exhibit B for the locations of the
inlets and storm sewer pipes.
Street Design: Typical Streets:
Standard Cross -Section (3% cross -slope, 27' B-B Residential Roadway)
Lay down curb and gutter on residential streets
Concrete Pavement
Standard recessed curb inlets (10' in length)
T,Methodology:
TR55
T, Minimum:
10 Minutes
Design Storm Event:
10 year design storm & 100 year analysis for residential and collector streets &
storm sewer
Pipe Materials:
Class III RCP, Profile Gasket in accordance with ASTM C443, ASTM C76 and
Corrugated HDPE Storm Sewer Pipe with smooth interior
Manning's n Values:
0.013 for pipes
0.018 for Streets
Runoff Coefficients:
0.55 for developed lots
0.65 for residential streets
Design Constraints:
Max. water depth in gutter: 4.5" or 0.375' for the 10 year design storm for
residential and collector streets
Min. pipe flow velocity: 2.5 fps
Max. pipe flow velocity: 15 fps
100-yr storm runoff maintained within the ROW (3" above curb)
25% reduction of cross -sectional area of pipes less than 24" in diameter
Min. I' freeboard for the 10 year design storm depth of flow
Design Software:
Excel Spreadsheets, Hydraflow Express Extension for AutoCAD Civil 3D 2013,
& Autodesk Civil 3D Storm Sewer Analysis.
The software was used to compute pipe capacities, flow rates and velocities,
compute hydraulic grade line elevations, headwater elevations, gutter depth &
inlet sizing.
The requirement for a 25% reduction in cross sectional area of pipes less than
24" diameter is achieved by using internal pipe diameters that are less than the
standard diameter. The 24" diameter pipe areas were reduced by 25% and a
20.6" diameter pipe was used in the analysis and the 18" diameter pipe areas
were reduced by 25% and a 15.6" diameter pipe was used in the analysis.
Design Results: The data presented in the Appendices indicates the gutter depth, inlet sizing,
pipe sizes and channel sizing is in accordance with the requirements of and the
City of College Station.
Applicable Exhibits: Exhibit A — Storm Sewer Design Post -Development Drainage Area Map
Exhibit B — Gutter Design Post -Development Drainage Area Map
Appendix A — Drainage Area Summary
Appendix Bl — Depth of Flow in Gutter
Appendix B2 — Storm Sewer Inlet Summary
Appendix C — Storm Sewer Pipe Summary
Appendix D — Technical Design Summary
CONCLUSION
The storm sewer drainage system for Phase 3 of the Spring Creek Townhomes Subdivision will function within the
requirements and restrictions of the BCS Design Guidelines.
I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this report for the
drainage design for Spring Creek Townhomes, Phase 3, was prepared by me in accordance with the requirements of
the Bryan/College Station Unified Drainage Design Guidelines for the owners of the property. All licenses and
permits required by any and all state and federal regulatory agencies for the proposed drainage improvements have
beenissued.
F—�
...... ..........
dOSERH� P.,.,SCHULTL�
asaas
7 �9,43
F-12327
SCHULTZ ;"g1NEMINGi LLCr
Nr','� '.1*9 M
Joseph ' Sch z, P.E.
EXHIBIT A
STORM SEWER DESIGN
POST -DEVELOPMENT
DRAINAGE AREA MAP
4
Iria Drive Spring Garden Drive BLOCK 3
Spring Garden Drive
BLOCR 2 3
il , 04
7 9 �6 — —
23 LD
0 COMYON BLOC 21
0 K2
2 0 2
17
4 13 14 15 16 19 20
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COMMON AREA
204A
Al 0.71
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SPRING CREEK TO WNHOMES STORM SEWER DESIGN SCALE EXHIBIT
PHASE 3 POST -DEVELOPMENT
COLLEGE STATION, TEXAS DRAINAGE AREA MAP A
EXHIBIT B
GUTTER DESIGN
POST -DEVELOPMENT
DRAINAGE AREA MAP
4
Iria Drive Spring Garden Drive BLOCK 3
Sminu, Garden Drive
3
9
BLOCK 2 21 22 21 23
2
2
121 10. 14 AC. 5 6 10 11 12 13 14 15 16 17 19
33
PJPWNE M WMT COMMON
M&4
W. 0. 16 AC. :MMON W LCOMMN ARM
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T- 204A
COWOM ARE4
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P U. LO' K4 CIMOM MIA
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201 24 25 26R VIL 28R 29RI30R it
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1 to' 24' HDPI B-pu- 1 o- it 'Loffr�' maam RUA 108
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TowNHOmEs GUTTER DESIGN �m SCALE EXHIBIT
PHASE 3 POST -DEVELOPMENT RNIZOW& 1'.100
COLLEGE STATION, TEXASDRAINAGE AREA MAP
F
APPENDIX A
DRAINAGE AREA SUMMARY
APPENDIX A
Spring Creek Townhomes Phases 2&3
Drainage Area Summary
Area #
Area, A
(acres)
C
tc
(min)
10 year storm
100 year storm
Im
(inlhr)
(cfs)
Q10f98h266)
Q100
(cfs)
201
1.20
0.630
14.7
7.265
5.49
7.43
202
1.08
0.640
15.9
6.991
4.83
6.54
202A
0.67
0.630
15.1
7.171
3.03
4.09
203A
1.04
0.610
14.7
7.265
4.61
6.23
2038
1.07
0.620
14.0
7.437
4.93
10.053
6.67
204A
0.71
0.610
12.7
7.782
3.37
10.510
4.55
204E
1.07
0.610
13.7
7.513
4.90
10.154
6.63
205
0.81
0.650
13.7
7.513F2.58
10.154
5.35
205A
0.53
0.650
12.3
7.89610.661
3.67
207
0.87
0.650
13.9
7.46210.087
5.70
208
0.11
0.660
10.0
8.63511.639
0.83
209
0.46
0.650
10.0
8.63511.639
3.48
210
0.04
0.650
10.0
8.635
11.639
0.30
211
0.03
0.650
10.0
8.635
0.17
11.639
0.23
212
0.91
0.650
10.0
8.635
5.11
11.639
6.88
The Rational Method;
Q = CIA
Q = Flow (cfs)
A = Area (acres)
C = Runoff Coeff.
I = Rainfall Intensity (in/hr)
Brazos County:
I = b / (tc+d)e tc = L/(V*60)
tc = Time of concentration (min) L = Length (ft
V = Velocity (ft/sec)
2 year storm 100 year storm
b=65 b=96
d= 8 d= 8.0
e = 0.806 e = 0.730
APPENDIX BI
DEPTH OF FLOW IN GUTTER
APPENDIX 61
Spring Creek Townhomes Phases 2&3
Depth of Flow in Gutter
(Refer to Exhibit B for Gutter Locations)
10-y .. ear .....
10-yst storm
Gutter/Inlet
Location
A
C
Slope
(ff/ft
tc
(min)
ha
(in/hr)
Qm
(cfs)
4ro+bypass
(cfs)
Yro. .l
V
(fps)
Area#
(acres)
(k)
(in)
1101
208
0.11
0.65
0.0100
10
6.327
0.62
-
0.146
1.76
1.73
1102
207
7.2
0.63
0.0100
14.7
5.248
5.49
-
0.332
3.99
2.98
1103
202
1.08
0.64
0.0200
15.9
5.034
4.83
-
0.278
3.34
3.75
1104A
207
0.87
0.65
0.0080
13.9
5.402
4.22
5.37
0.344
4.12
2.14
1104B
210
0.04
0.65
0.0080
10
6.327
0.22
0.22
0.104
1.25
1.23
1105A
211
0.03
0.65
0.0080
10
6.327
0.17
-
0.094
1.13
1.15
1105B
205
0.87
0.65
0.0080
13.7
5.442
3.96
-
0.306
3.68
2.53
1106A
209
0.46
0.65
0.0080
10
6.327
2.58
-
0.261
3.13
2.27
1106B
212
0.91
0.65
0.0080
10
6.327
5.71
-
0.337
4.05
2.70
1107A
2038
1.07
0.62
0.0080
14
5.382
4.93
5.34
0.343
4.11
2.52
1707E
204A
0.71
0.61
0.0080
12.7
5.653
3.37
3.67
0.304
3.65
2.19
1108
203A
1.04
0.61
0.0080
14.7
5.248
4.61
-
0.324
3.89
2.63
1109
204B
1.07
0.61
0.0080
13.7
5.442
4.90
-
0.332
3.96
2.67
Al
202A
0.670
0.63
0.0200
15.100
5.174
3.03
-
0.233
2.80
3.34
A2
201
1200.
0.63
0.0200
14.700
5.248
5.49
-
0.292
3.50
3.87
A3
202
1.080
0.64
0.0200
15.900
5.034
4.83
-
0.278
3.34
3.75
A4
207
0.870
0.65
0.0070
13.900
5.402
4.22
-
0.322
3.86
2.44
A5
209
0.460
0.65
0.0150
10.000
6.327
2.58
-
0.232
2.78
2.88
A6
212
0.910
0.65
0.0120
10.000
6.327
5.11
-
0.312
3.75
3.14
A7
206
0.810
0.65
0.0200
13.700
5.442
3.96
-
0.258
3.10
3.57
B1
207
1.200
0.63
0.0100
14.700
5.248
5.49
-
0.332
3.99
2.98
B2
208
0.110
0.65
0.0100
10.000
6.327
0.62
-
0.146
1.76
1.73
Cl
204A
0.710
0.61
0.0080
12.700
5.653
3.37
-
0.288
3.46
2.43
C2
203E
1.070
0.62
0.0080
14.000
5.382
4.93
-
0.333
3.99
C3
205A
0.530
0.65
0.0080
12.300
5.742
2.72
-
0.266
3.19
C4
2048
1.070
0.61
0.0080
13.700
5.442
4.90
-
0.332
3.98
A
C5
203A
1.040
0.61
0.0080
14.700
5.248
4.61
-
0.324
3.89
Standard Curb - 10-yr storm max design depth - 4.6'
Transverse (Crown) slope (ft/ft)
27 street = 0.0300
38 street = 0.0300
Straight Crown Flow (Solved to find actual depth of flow in gutter, v),
Q = 0.56 . (zln) . Svz . Y ra rt, y = (Q / [0.56 . (zln) . Sv2]}ma
n = Roughness Coefficient = 0.018
S = Street/Gutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
z = Reciprocal of crown slope:
APPENDIX B1
Spring Creek Townhomes Phases 2&3
Depth of Flow in Gutter
(Refer to Exhibit B for Gutter Locations)
100-year storm
Gutterlinlet
Location
A
C
Slope
(ft/ft)
tc
(min)
1100
(in/hr)
Q100
(cfs)
Qua * bypass Y
(cfs)
Yioo
Allowable
Depth
V
(fps)
Area #
(acres)
(ft)
(in)
1101
208
0.11
0.65
0.0100
10
11.639
0.83
-
0.164
1.96
8"
1.86
1102
201
1.2
0.63
0.01 00
14.7
9.826
7.43
-
0.372
4.47
e"
3.22
1103
202
1.08
0.64
0.0200
15.9
9.463
6.54
-
0.312
3.74
8"
4.04
1104A
207
0.87
0.65
0.0080
13.9
10.087
5.70
7.75
0.394
4.73
8"
2.20
11048
210
0.04
0.65
0. i08o
10
11.639
0.30
0.30
0.117
1.40
8"
1.33
1105A
211
0.03
0.65
0.0080
10
11.639
0.23
-
0.105
1.26
V
1.24
1105B
205
0.81
0.65
0.0080
13.7
10.154
5.35
-
0.343
4.12
8"
2.73
1106A
209
0.46
0.65
0.0080
10
11.639
3.48
-
0.292
3.50
8"
2.45
I106B
212
0.91
0.65
0.0080
10
11.639
6.88
-
0.377
4.53
e"
2.90
1107A
2036
1.07
0.62
0.0080
14 -
10.053
6.67
7.65
0.392
4.71
8"
2.60
1107B
204A
0.71
0.61
0.0080
12.7
10.510
4.55
5.70
0.351
4.21
8"
2.21
I708
203A
1.04
0.61
0.0080
14.7
9.826
6.23
-
0.363
4.36
8"
2.83
1109
2048
1.07
0.61
0.0080
13.7
10.154
6.63
-
0.372
4.46
8"
2.88
Al
202A
0.670
0.63
0.0200
15.100
9.701
4.09
-
0.261
3.14
8"
3.60
A2
201
1.200
0.63
0.0200
9.826
7.43
-
0.327
3.92
8"
4.17
A3
202
1.080
0.64
0.0200
9.463
6.54
-
0.312
3.74
8"
4.04
A4
207
0.870
0.65
0.0070
10.087
5.70
-
0.360
4.32
8"
2.64
A5
209
0.460
0.65
0.0150
K14.700
11.639
3.48
-
0.260
3.11
8"
3.10
A6
212
0.910
0.65
0.0120
11.639
6.88
-
0.349
4.19
8"
3.38
A7
205
0.810
0.65
0.0200
10.154
5.35
-
0.289
3.47
8"
3.85
81
201
1.200
0.63
0.0100
9.826
7.43
-
0.372
4.47
8"
3.22
B2
208
0.110
0.65
0.0100
10.000
11.639
0.83
-
0.164
1.96
8"
1.86
Cl
204A
0.710
0.61
0.0080
12.700
10.510
4.55
-
0.323
3.87
8"
2.62
C2
2038
1.070
0.62
0.0080
14.000
10.053
6.67
-
0.373
4.47
8"
2.88
C3
205A
0.530
0.65
0.0080
12.300
10.661
- 3.67
-
0.298
3.58
8"
2.48
C4
204B
1.070
0.61
0,0080
13.700
10.154
6.63
-
0.372
4.46
8"
2.88
C5
203A
1.040
0.61
0.0080
14.700
9.826 1
6.23
-
0.363
4.36
8"
2.83
Transverse (Crown) slope (fUft)
27 street = 0.0300
38 street = 0,0300
Straight Crown Flow (Solved to find actual depth of flow In nutter
Q = 0.56 * (zln) * Svz * yera K, y = (Q / [0.56 * (z/n) * Svz[)"o
n = Roughness Coefficient = 0.018
S = Street/Gutter Slope (ft/ft)
y = Depth of flow at inlet (ft)
z = Reciprocal of crown slope:
27' street = 33
100-year storm
Top of
Curb
GuttefRunoff,
FL
ROWS
Elev,
Freeboard
ft.
-0.50
0.23
0.57
-0.50
0.23
0.36
-0.50
0.23
0.42
-0.50
-0.106
0.23
0.34
0.00
-0.50
-0.38
0.23
0.61
-0.50
-0.395
0.23
0.63
0.00
-0.50
-0.16
0.23
0.39
-0.50
-0.208
0.23
0.44
0.00
-0.50
-0.12
0.23
0.35
-0.50
-0.108
0.23
0.34
0.00
-0.50
-0.15
0.23
0.38
-0.50
-0.137
0.23
0.37
-0.50
-0.128
0.23
0.36
-0.50
-0.24
0.23
0.47
-0.50
-0.17
0.23
0.40
-0.50
-0.19
0.23
0.42
-0.50
-0.14
0.23
0.37
.0.50
-0.24
0.23
0.47
-0.50
-0.15
0.23
0.38
-0.50
-0.21
0.23
0.44
-a50
-0.13
0.23
0.36
-0.50
-0.34
0.23
0.57
-0.50
-0.18
0.23
0.41
-0.50
-0.13
0.23
0.36
-0.50
-0.20
0.23
0.43
-0.50
-0.13
0.23
0.36
-0.50
-0.14
0.23
0.37
APPENDIX B2
STORM SEWER INLET SUMMARY
APPENDIX B2
Spring Creek Townhomes Phases 2&3
Storm Sewer Inlets on Grade - Design Analysis
Inlet Length Street Q10 1-10, ft. Bypass
Q100 L100, ft. Bypass
- No. ft. Slope cfs Design cfs
cfs Design cfs
1102 15 1.00% 5.49 15.71 0.02
7.43 18.10 0.31
1103 10 2.00% 4.83 18.21 1.15
6.54 20.99 2.04
1108 10 0.80% 4.61 13.53 0.41
6.23 15.59 0.98
* Inlet 1101 & 1102 Drain into existing Deacon
Assume 10% clogging for design
Se = Sx + (a/w)* Eo
Eo= Qw/Q = 1 - [ 1 - W/T]2.67
L=Kc*Q0A7*So.3*(1 /(n*Se))"'
W = Width of Depressed Gutter (ft) = 2
Sx=Cross flow of Road Surface 0.03
T=Total Spread of water in gutter (ft) 12.5
a=Gutter depression depth (ft)= 0.33
n=Manning's Roughness Coefficient= 0.018
Kc= 0.6
Qw=Flow in width, W
E=Efficiency of inlet or percentage of interception
S=longitudinal Slope
-- Li=Curb opening length
Se = Sx + (a/w)* Eo 0.091412
Eo= Qw/Q = 1 - [ 1 - W/T]2'67 0.372194
APPENDIX Cl
STORM SEWER PIPE SUMMARY
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APPENDIX D
TECHNICAL DESIGN SUMMARY
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
The Cities of Bryan and College Station both require storm drainage design to follow these
Unified Stormwater Design Guidelines. Paragraph C2 of Section III (Administration) requires
submittal of a drainage report in support of the drainage plan (stormwater management plan)
proposed in connection with land development projects, both site projects and. subdivisions.
That report may be submitted as a traditional prose report, complete with applicable maps,
graphs, tables and drawings, or it may take the form of a `Technical Design Summary". The
format and content for such a summary report shall be in substantial conformance with the
description in this Appendix to those Guidelines. In either format the report must answer the
questions (affirmative or negative) and provide, at minimum, the information prescribed in the
"Technical Design Summary" in this Appendix.
The Stormwater Management Technical Design Summary Report shall include several parts
as listed below. The information called for in each part must be provided as applicable. In
addition to the requirements for the Executive Summary, this Appendix includes several
pages detailing the requirements for a Technical Design Summary Report as forms to be
completed. These are provided so that they may be copied and completed or scanned and
digitized. In addition, electronic versions of the report forms may be obtained from the City.
Requirements for the means (medium) of submittal are the same as for a conventional report
as detailed in Section III of these Guidelines.
Note: Part 1 — Executive Summary must accompany any drainage report
required to be provided in connection with any land development project,
regardless of the format chosen for said report.
Note: Parts 2 through 6 are to be provided via the forms provided in this
Appendix. Brief statements should be included in the forms as requested,
but additional information should be attached as necessary.
Part 1 — Executive Summary Report
Part 2 — Project Administration
Part 3 — Project Characteristics
Part 4 — Drainage Concept and Design Parameters
Part 5 — Plans and Specifications
Part 6 — Conclusions and Attestation
STORMWATER MANAGEMENT TECHNICAL DESIGN SUMMARY REPORT
Part 1 - Executive Summary
This is to be a brief prose report that must address each of the seven areas listed below.
Ideally it will include one or more paragraphs about each item.
1. Name, address, and contact information of the engineer submitting the report, and
of the land owner and developer (or applicant if not the owner or developer). The
date of submittal should also be included.
2. Identification of the size and general nature of the proposed project, including any
proposed project phases. This paragraph should also include reference to
STORMWATER DESIGN GUIDELINES Page 1 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
applications that are in process with either City: plat(s), site plans, zoning requests,
or clearing/grading permits, as well as reference to any application numbers or
codes assigned by the City to such request.
3. The location of the project should be described. This should identify the Named
Regulatory Watershed(s) in which it is located, how the entire project area is
situated therein, whether the property straddles a watershed or basin divide, the
approximate acreage in each basin, and whether its position in the Watershed
dictates use of detention design. The approximate proportion of the property in the
city limits and within the ETJ is to be identified, including whether the property
straddles city jurisdictional lines. If any portion of the property is in floodplains as
described in Flood Insurance Rate Maps published by FEMA that should be
disclosed.
4. The hydrologic characteristics of the property are to be described in broad terms:
existing land cover; how and where stormwater drains to and from neighboring
properties; ponds or wetland areas that tend to detain or store stormwater; existing
creeks, channels, and swales crossing or serving the property; all existing drainage
easements (or ROW) on the property, or on neighboring properties if they service
runoff to or from the property.
5. The general plan for managing stormwater in the entire project area must be
outlined to include the approximate size, and extent of use, of any of the following
features: storm drains coupled with streets; detention / retention facilities; buried
conveyance conduit independent of streets; swales or channels; bridges or culverts;
outfalls to principal watercourses or their tributaries; and treatment(s) of existing
watercourses. Also, any plans for reclaiming land within floodplain areas must be
outlined.
Coordination and permitting of stormwater matters must be addressed. This is to
include any specialized coordination that has occurred or is planned with other
entities (local, state, or federal). This may include agencies such as Brazos County
government, the Brazos River Authority, the Texas A&M University System, the
Texas Department of Transportation, the Texas Commission for Environmental
Quality, the US Army Corps of Engineers, the US Environmental Protection Agency,
et al. Mention must be made of any permits, agreements, or understandings that
pertain to the project.
Reference is to be made to the full drainage report (or the Technical Design
Summary Report) which the executive summary represents. The principal
elements of the main report (and its length), including any maps, drawings or
construction documents, should be itemized. An example statement might be:
"One -page drainage report dated , one set of
construction drawings (_sheets) dated and a
-page specifications document dated comprise
the drainage report for this project."
STORMWATER DESIGN GUIDELINES Page 2 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 2 — Project Administration
Start (Page 2.1)
"Engineering and
Design Profession
Engineering Firm Name and Address:
Jurisdiction
Schultz Engineering, LLC
City: Bryan
P.O. Box 11995
✓ College Station
College Station, Tx 77842
Date of Submittal:
July 2013
Lead Engineer's Name and Contact Info.(phone, e-mail, fax):
Other:
Joseph A Schultz, PE email: joeschaltz84@verizon.net
Phone:764-3900 fax:764-3910
Supporting Engineering / Consulting Firm(s):
Other contacts:
n/a
Developer / Owner h Applicant Information
Developer / Applicant Name and Address:
Phone and e-mail:
Spring Creek CS Development LTD
979-690-7250
4490 Castlegate Dr
College Station, Tx 77845
Property Owner(s) if not Developer / Applicant (& address):
Phone and e-mail:
Project Identification
Development Name: Spring Creek Townho,nes Phase 3
Is subject property a site project, a single-phase subdivision, or part of a multi -phase subdivision?
Multi -Phase Subdivision If multi -phase, subject property is phase 4 of 4
Legal description of subject property (phase) or Project Area:
(see Section II, Paragraph B-3a)
Robert Stevenson League, A-54
If subject property (phase) is second or later phase of a project, describe general status of all
earlier phases. For most recent earlier phase Include submittal and review dates.
Housing construction is ongoing in the previous phase 2
General Location of Project Area, or subject property (phase):
Between Decatur Drive and Spring Hill Drive.
In City Limits?
Extraterritorial Jurisdiction (acreage):
Bryan: acres.
Bryan: College Station:
College Station: 5.309 acres.
Acreage Outside ETJ:
STORMWATER DESIGN GUIDELINES Page 3 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 2 — Project Administration
Continued (page 2.2)
Protect Identification (continued)
Roadways abutting or within Project Area or
Abutting tracts, platted land, or built
subject property:
developments:
Decatur Drive
Spring Creek Gardens Phase I
Spring Creek Townhomes Phase 2
Named Regulatory Watercourse(s) & Watershed(s):
Tributary Basin(s):
Spring Creek
Spring Creek Tributary A
Plat Information ror Project or;Subject Properly (or Phase):':
Preliminary Plat File #: 08- 00500003 Final Plat File #: NIA Date: duly 2013
Name: Spring Crk THPh 2&3 (PP) Status and Vol/Pg: submitted with this project
If two plats, second name: File #:
Status: Date:
Zoning Information For Projector Subject Property (or Phase):
Zoning Type: PDD Existing or Proposed? Existing Case Code:
Case Date Status:
Zoning Type: Existing or Proposed? Case Code:
Case Date Status:
Stormwater Management Planning For Projector Subject Property (or; Phase),-,'.:,i"
Planning Conference(s) & Date(s):
Participants:
N/A
Preliminary Report Required? NIA Submittal Date Review Date
Review Comments Addressed? Yes _ No _ In Writing? When?
Compliance With Preliminary Drainage Report. Briefly describe (or attach documentation
explaining) any deviation(s) from provisions of Preliminary Drainage Report, if any.
STORMWATER DESIGN GUIDELINES Page 4 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 2 — Proiect Administration
Continued (page 2.3)
Coordination For Projector Subject Property (or Phase),
Note: For any Coordination of stormwater matters indicated below, attach documentation
describing and substantiating any agreements, understandings, contracts, or approvals.
Dept.
Contact:
Date:
Subject:
Coordination
With Other
Departments of
Jurisdiction
City (Bryan or
College Station)
Coordination With
Summarize need(s) & actions taken (include contacts & dates):
Non -jurisdiction
City Needed?
Yes _ No ✓
Coordination with
Summarize need(s) & actions taken (include contacts & dates):
Brazos County
Needed?
Yes _ No ✓
Summarize need(s) & actions taken (include contacts & dates):
Coordination with
TxDOT Needed?
Yes No ✓
Summarize need(s) & actions taken (include contacts & dates):
Coordination with
TAMUS Needed?
Yes —No ✓
Permits For Projector Subject; Property (or Phase)
As to stormwater management, are permits required for the proposed work from any of the entities
listed below? If so, summarize status of efforts toward that objective ins aces below.
Entity
Permitted or
Status of Actions (include dates)
'
Approved .
US Army Crops of
Engineers
No ✓ Yes ✓
US Environmental
Protection Agency
No ✓ Yes _
Texas Commission on
Environmental Quality
No Yes ✓
Brazos River
Authority
No ✓ Yes
STORMWATER DESIGN GUIDELINES Page 5 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D —TECHNICAL DESIGN SUMMARY
Part 3 — Property Characteristics
Start (Page 3.1)
Nature and Scope of Proposed Work
Existing: Land proposed for development currently used, including extent of impervious cover?
Proposed development is residential subdivision. High density. Impervious cover = 65%
Redevelopment of one platted lot, or two or more adjoining Platted lots.
Site
Development
Building on a single lam tted lot of undeveloped land.
Project
Building on two or more platted adjoining lots of undeveloped land.
(select all
Building on a single lot, or adjoining lots, where proposed plat will not form
applicable)
a new street (but may include ROW dedication to existing streets).
_ Other (explain):
Subdivision
_ Construction of streets and utilities to serve one or more lap tted lots.
Development
✓ Construction of streets and utilities to serve one or more proposed lots on
Project
lands represented by pending plats.
Site projects: building use(s), approximate floor space, impervious cover ratio.
Subdivisions: number of lots by general type of use, linear feet of streets and
Describe
drainage easements or ROW.
Nature and
Size of
42lots. Approximately 786' of Streets.
Proposed
Project
1.04 ac. -ROW
Is any work planned on land that is not platted
If yes, explain:
or on land for which platting is not pending?
✓ No Yes
FEMA Floodplains,
Is any part of subject property abutting a Named Regulatory Watercourse
No ✓ Yes
(Section II, Paragraph B1) or a tributary thereof?
—
Is any part of subject property in floodplain
No ✓ Yes Rate Map
area of a FEMA-regulated watercourse?
Encroachments)
Encroachment purpose(s): Building site(s) Road crossing(s)
into Floodplain
areas planned?
Utility crossing(s) _ Other (explain):
No ✓
Yes
If floodplain areas not shown on Rate Maps, has work been done toward amending the FEMA-
approved Flood Study to define allowable encroachments in proposed areas? Explain.
STORMWATER DESIGN GUIDELINES Page 6 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 3 — Property Characteristics
Continued (Page 3.2)
Hydrologic Attributes of Subject Property (or Phase),,"',,..,
Has an earlier hydrologic analysis been done for larger area including subject property?
Reference the study (& date) here, and attach copy if not already in City files.
Yes
Crowley Tract Detention Pond
Is the stormwater management plan for the property in substantial conformance with the
earlier study? Yes_ %/ _ No_ _ If not, explain how it differs.
If subject property is not part of multi -phase project, describe stormwater management
No
plan for the property in Part 4.
If property is part of multi -phase project, provide overview of stormwater management plan
for Project Area here. In Part 4 describe how plan for subject property will comply
therewith.
Do existing topographic features on subject property store or detain runoff? ✓ No Yes
Describe them (include approximate size, volume, outfali, model, etc).
Any known drainage or flooding problems in areas near subject property? ✓ No Yes
Identify:
Based on location of study property in a watershed, is Type 1 Detention (flood control) needed?
(see Table B-1 in Appendix B) Already Provided in Crowley Tract Detention
✓ Detention is required. Need must be evaluated. Detention not required.
What decision has been reached? By whom?
If the need for
How was determination made?
Type 1 Detention
must be evaluated:
STORMWATER DESIGN GUIDELINES Page 7 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 3 — Property Characteristics
Continued (Page 3.3)
Hydrologic, .ttrlWtes of Subject Prope►ty (or Phase) (continued)
Does subject property straddle a Watershed or Basin divide? ✓ No Yes If yes,
describe splits below. In Part 4 describe design concept for handling this.
Watershed or Basin
Larger acreage
Lesser acreage
Above -Project Areas(Section 11, Paragraph B3-a)
Does Project Area (project or phase) receive runoff from upland areas? ✓ No _ Yes
Size(s) of area(s)in acres: 1) 2) 3) 4)
Flow Characteristics (each instance) (overland sheet, shallow concentrated, recognizable
concentrated section(s), small creek (non -regulatory), regulatory Watercourse or tributary);
Flow determination: Outline hydrologic methods and assumptions:
Does storm runoff drain from public easements or ROW onto or across subject property?
✓ No Yes If yes, describe facilities in easement or ROW:
Are changes in runoff characteristics subject to change in future? Explain
Conveyance Pathways (Section 11, Paragraph C2)
Must runoff from study property drain across lower properties before reaching a Regulatory
Watercourse or tributary? ✓ No Yes
Describe length and characteristics of each conveyance pathway(s). Include ownership of
property(ies).
STORMWATER DESIGN GUIDELINES Page 8 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 3 — Property Characteristics
Continued (Page 3.4)
Hydrologic Attributes of Subject Property (continued) (or Phase) (c
Conveyance Pathways (continued)
Do drainage
If yes, for what part of length? % Created by? u plat, or
easements
instrument. If instrument(s), describe their provisions.
exist for any
part of
pathway(s)?
✓ No
Yes
Where runoff must cross lower properties, describe characteristics of abutting lower
property(ies). (Existing watercourses? Easement or Consent aquired?)
Pathway
Areas
Describe any built or improved drainage facilities existing near the property (culverts,
bridges, lined channels, buried conduit, swales, detention ponds, etc).
Detention: Pond constructed with the Crowley Tract
Nearby
Drainage
Do any of these have hydrologic or hydraulic influence on proposed stormwater
Facilities
design? ✓ No _Yes If yes, explain:
STORMWATER DESIGN GUIDELINES Page 9 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Start (Page 4.1)
stormwater Management Concept
Discharge(s) From Upland Area(s)
If runoff is to be received from upland areas, what design drainage features will be used to
accommodate it and insure it is not blocked by future development? Describe for each area,
flow section, or discharge point.
Discharge(s) To Lower Property(ies) (Section II, Paragraph E1)
Does project include drainage features (existing or future) proposed to become public via
platting? ✓ No _Yes Separate Instrument? ✓ No _Yes
Per Guidelines reference above, how will
Establishing Easements (Scenario 1)
runoff be discharged to neighboring
Pre -development Release (Scenario 2)
property(ies)?
Combination of the two Scenarios
Scenario 1: If easements are proposed, describe where needed, and provide status of actions
on each. (Attached Exhibit # )
Scenario 2: Provide general description of how release(s) will be managed to pre -development
conditions (detention, sheet flow, partially concentrated, etc.). (Attached Exhibit #)
Combination: If combination is proposed, explain how discharge will differ from pre -
development conditions at the property line for each area (or point) of release.
If Scenario 2, or Combination are to be used, has proposed design`been coordinated with
owner(s) of receiving property(ies)? No Yes Explain and provide
documentation.
STORMWATER DESIGN GUIDELINES Page 10 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.2)
Stormwiater, Management Concept (continued)'
Within Project Area Of Multi -Phase Project
Identify gaining Basins or Watersheds and acres shifting:
Will project result
in shifting runoff
between Basins or
between
What design and mitigation is used to compensate for increased runoff
Watersheds?
from gaining basin or watershed?
✓ No
Yes
How will runoff from Project
1. With facility(ies) involving other development projects.
Area be mitigated to pre-
2 Establishing features to serve overall Project Area.
development conditions?
Select any or all of 1, 2,
3. — On phase (or site) project basis within Project Area.
and/or 3, and explain below.
1. Shared facility (type & location of facility; design drainage area served; relationship to size of
Project Area): (Attached Exhibit # )
2. For Overall Proiect Area (type & location of facilities): (Attached Exhibit # )
3. By phase (or site) project: Describe planned mitigation measures for phases (or sites) in
subsequent questions of this Part.
Are aquatic echosystems proposed? No Yes In which phase(s) or
project(s)?
C'•
a
Y
Are other Best Management Practices for reducing stormwater pollutants proposed?
a
No Yes Summarize type of BMP and extent of use:
y
c
rn
.y
(D O
Z
a✓
If design of any runoff -handling facilities deviate from provisions of B-CS Technical
Specifications, check type facility(ies) and explain in later questions.
rn
2
Detention elements Conduit elements Channel features
—
Swales Ditches — Inlets Valley gutters _ Outfalls
Culvert features — Bridges Other
STORMWATER DESIGN GUIDELINES Page 11 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.3)
'Stormwater Management Concept (continued)'
Within Project Area Of Multi -Phase Project (continued)
Will Project Area include bridge(s) or culvert(s)? ✓ No Yes Identify type and
general size and In which phase(s).
If detention/retention serves (will serve) overall Project Area, describe how it relates to subject
phase or site project (physical location, conveyance pathway(s), construction sequence):
The detention pond constructed with the Crowley Tract
Within Or Serving Subject Property (Phase, or Site)
If property part of larger Project Area, is design in substantial conformance with earlier analysis
and report for larger area? ✓ Yes No, then summarize the difference(s):
Identify whether each of the types of drainage features listed below are included, extent of use,
and general characteristics.
Typical shape? Surfaces?
C'•
v
jd
Steepest side slopes:
Usual front slopes:
Usual back slopes:
N }
Flow line slopes: least
I Typical distance from travelway:
=o
(Do
typical greatest
(Attached Exhibit # )
O
v Z
fl
ca
2 ✓
Are longitudinal culvert ends in compliance with B-CS Standard Specifications?
2
Yes No, then explain:
m
At intersections or otherwise, do valley gutters cross arterial or collector streets?
°'
✓ No Yes if yes explain:
U �
L
. u)
w
Are valley gutters proposed to cross any street away from an intersection?
z
✓ No Yes Explain: (number of locations?)
N �
_
C
d �
Q
STORMWATER DESIGN GUIDELINES Page 12 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Desiqn Parameters
Continued (Page 4.4)
Stormwater Management Concept (continued),
Within Or Serving Subject Property (Phase, or Site) (continued)
Gutter line slopes: Least 0.8 Usual 0.80 Greatest 2.00
Are inlets recessed on arterial and collector streets? ✓ Yes No If "no",
identify where and why.
Will inlets capture 10-year design stormflow to prevent flooding of intersections (arterial
with arterial or collector)? ✓ Yes No If no, explain where and why not.
C.-
'a
Will inlet size and placement prevent exceeding allowable water spread for 10-year
design storm throughout site (or phase)? / Yes No If no, explain.
rn
c �
�
Sag curves: Are inlets placed at low points? ✓ Yes No Are inlets and
g Y
conduit sized to prevent 100-year stormflow from ponding at greater than 24 inches?
s u
✓ Yes No Explain "no" answers.
a�
m
E
Will 100-yr stormflow be contained in combination of ROW and buried conduit on
whole length of all streets? ✓ Yes No If no, describe where and why.
Do designs for curb, gutter, and inlets comply with B-CS Technical Specifications?
✓ Yes No if not, describe difference(s) and attach justification.
Are any 12-inch laterals used? ✓ No Yes Identify length(s) and where
used.
tiw
Pipe runs between system
Typical 231' Longest 231'
}
access points
mAre
junction boxes used at each bend? ✓ Yes No If not, explain where
N
and why.
c
.ro o
z
a
E
c,
Svc,
Are downstream soffits at or below upstream soffits?
Least amount that hydraulic
2
Yes ✓ No If not, explain where and why:
grade line is below gutter line
_
(system -wide):
1.83'
STORMWATER DESIGN GUIDELINES Page 13 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.5)
Stormwater Management t6ncept,(continued) :
Within Or Serving Subject Property (Phase, or Site) (continued)
Describe watercourse(s), or system(s) receiving system discharge(s) below
(include design discharge velocity, and angle between converging flow lines).
U
C
1) Watercourse (or system), velocity, and angle?
c
Pipe 6 Outfall: Velocity 6.26 fps.
a�
—0
E
2) Watercourse (or system), velocity, and angle?
c o
c d
U C
a) E
y y
—
w
3) Watercourse (or system), velocity, and angle?
cn
cnCD
g
j
O
O
p.
E
For each outfall above, what measures are taken to prevent erosion or scour of
receiving and all facilities at juncture?
w
(D
1) Outfall from this development will occur into downstream pipes from prev. phases
m
Q
2)
y
0
3)
Are swale(s) situated along property lines between properties? No Yes
Number of instances: For each instance answer the following questions.
Surface treatments (including low -flow flumes if any):
c
N
N
N
N }
Flow line slopes (minimum and maximum):
m
0
Z
Outfall characteristics for each (velocity, convergent angle, & end treatment).
N
10
3
y
N
Will 100-year design storm runoff be contained within easement(s) or platted drainage
ROW in all instances? Yes _ No If "no" explain:
STORMWATER DESIGN GUIDELINES Page 14 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Desian Parameters
Continued (Page 4.6)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Are roadside ditches used? ✓ No Yes If so, provide the following:
r
Is 25-year flow contained with 6 inches of freeboard throughout ? Yes No
_ _
Are top of banks separated from road shoulders 2 feet or more? Yes No
m
_ _
Are all ditch sections trapezoidal and at least 1.5 feet deep? _ Yes No
N
For any "no" answers provide location(s) and explain:
a
m
0
K
If conduit is beneath a swale, provide the following information (each instance).
Instance 1 Describe general location, approximate length:
N
Is 100-year design flow contained in conduit/swale combination? —Yes —No
If "no" explain:
T
o m
Space for 100-year storm flow? ROW Easement Width
Z c
Swale Surface type, minimum
Conduit Type and size, minimum and maximum
and maximum slopes:
slopes, design storm:
c
0
N a
m
Inlets Describe how conduit is loaded (from streets/storm drains, inlets by type):
c A
N C
t �
U P
G `�
o
Access Describe how maintenance access is provided (to swale, into conduit):
0
m
0
o €
a) o
a)G
=
_a)
Instance 2 Describe general location, approximate length:
E
U) N
c
Is 100-year design flow contained in conduit/swale combination? Yes No
° o
_ _
If "no" explain:
m n
C
t
Space for 100-year storm flow? ROW Easement Width
Swale Surface type, minimum
Conduit Type and size, minimum and maximum
a;
m
and maximum slopes:
slopes, design storm:
c Co
yInlets
Describe how conduit is loaded (from streets/storm drains, inlets by type):
m c
3 0
N
Access Describe how maintenance access is provided (to swale, into conduit):
STORMWATER DESIGN GUIDELINES Page 15 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.7)
$torinwater Management Coricept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
If "yes" provide the following information for each instance:
Instance 1 Describe general location, approximate length, surfacing:
c
a
o
W
ti-_ 6
Is 100-year design flow contained in swale? Yes No Is swale wholly
}
_
within drainage ROW? Yes No Explain "no" answers:
L)
Access Describe how maintenance access is provide:
o
Z
v
o✓
Instance 2 Describe general location, approximate length, surfacing:
d
c �•
� N
L1 C
N
'o E
L N
3 m
Is 100-year design flow contained in swale? —Yes —No Is swale wholly
owithin
drainage ROW? Yes No Explain "no" answers:
O
W
Access Describe how maintenance access is provided:
_U
d
a
Instance 3. 4, etc. If swales are used in more than two instances, attach sheet
providing all above information for each instance:
"New" channels: Will any area(s) of concentrated flow be channelized (deepened,
widened, or straightened) or otherwise altered? _ No Yes If only slightly
shaped, see "Swales" in this Part. If creating side banks, provide information below.
C1•
Will design replicate natural channel? _Yes No If "no", for each instance
o Q
describe section shape & area, flow line slope (min. & max.), surfaces, and 100-year
2 'uf
design flow, and amount of freeboard:
°-
Instance 1:
c �
E
'o
Instance 2:
a
E O
Z
C ✓
c
Instance 3:
m
s
U
STORMWATER DESIGN GUIDELINES Page 16 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.8)
Stormwater Management Concept (continued)+
Within Or Serving Subject Property (Phase, or Site) (continued)
Existing channels (small creeks): Are these used? No Yes
If "yes" provide the information below.
Will small creeks and their floodplains remain undisturbed? —Yes No How
many disturbance instances? Identify each planned location:
For each location, describe length and general type of proposed improvement
(including floodplain changes):
For each location, describe section shape & area, flow line slope (min. & max.),
surfaces, and 100-year design flow.
a
c
c
Watercourses (and tributaries): Aside from fringe changes, are Regulatory
Watercourses proposed to be altered? No Yes Explain below.
c
Submit full report describing proposed changes to Regulatory Watercourses. Address
E
existing and proposed section size and shape, surfaces, alignment, flow line changes,
length affected, and capacity, and provide full documentation of analysis procedures
a
and data. Is full report submitted? Yes No if "no" explain:
E
c
c
vAll
Proposed Channel Work: For all proposed channel work, provide information
requested in next three boxes.
If design is to replicate natural channel, identify location and length here, and describe
design in Special Design section of this Part of Report.
Will 100-year flow be contained with one foot of freeboard? —Yes —No If
not, identify location and explain:
Are ROW / easements sized to contain channel and required maintenance space?
Yes _ No If not, identify location(s) and explain:
STORMWATER DESIGN GUIDELINES Page 17 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.9)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
How many facilities for subject property project? For each provide info. below.
For each dry -type facilitiy:
Facility 1
Facility 2
Acres served & design volume + 10%
100-yr volume: free flow & plugged
Design discharge (10 yr & 25 yr)
Spillway crest at 100-yr WSE?
yes no
yes no
Berms 6 inches above plugged WSE?
yes _ no
yes _no
Explain any "no" answers:
N
N
}
For each facility what is 25-yr design Q, and design of outlet structure?
Facility 1:
0
Z
Facility 2:
Do outlets and spillways discharge into a public facility in easement or ROW?
Facility 1: —Yes —No Facility 2: —Yes —No
a(D
If "no" explain:
O
O.
O
°-
For each, what is velocity of 25-yr design discharge at outlet? & at spillway?
w
Facility 1: & Facility 2: &
Are energy dissipation measures used? Describe type and
co
LL•
—No —Yes
location:
c
0
c
N
d
E
Q
For each, is spillway surface treatment other than concrete? Yes or no, and describe:
Facility 1:
Facility 2:
For each, what measures are taken to prevent erosion or scour at receiving facility?
Facility 1:
Facility 2:
If berms are used give heights, slopes and surface treatments of sides.
Facility 1:
Facility 2:
STORMWATER DESIGN GUIDELINES Page 18 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.10)
Stormwater Management Goricept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Do structures comply with B-CS Specifications? Yes or no, and explain if "no":
Facility 1;
ii z
Facility 2:
C .—
o c
c U
N v
oFor
additional facilities provide all same information on a separate sheet.
Are parking areas to be used for detention? No Yes What is
maximum depth due to required design storm?
Roadside Ditches: Will culverts serve access driveways at roadside ditches?
No _ Yes If "yes", provide information in next two boxes.
Will 25-yr. flow pass without flowing over driveway in all cases? Yes _ No
Without causing flowing or standing water on public roadway? Yes _ No
Designs & materials comply with B-CS Technical Specifications? Yes _ No
Explain any "no" answers:
r
W
m
c
oAre
culverts parallel to public roadway alignment? Yes No Explain:
U
i6
CL
Creeks at Private Drives: Do private driveways, drives, or streets cross drainage
m
ways that serve Above -Project areas or are in public easements/ ROW?
NZ
No Yes If "yes" provide information below.
How many instances? Describe location and provide information below.
r
Location 1:
V
2
Location 2:
Location 3:
For each location enter value for:
1
2
3
Design year passing without toping travelway?
Water depth on travelway at 25-year flow?
Water depth on travelway at 100-year flow?
For more instances describe location and same information on separate sheet.
STORMWATER DESIGN GUIDELINES Page 19 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMA�
Part 4 — Drainage Concept and Design Parameters Continued (Page 4.1—�� Y
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
d
E
0
IMMIMU nUUMMUI V VVMVIGVUI5W3 IW I IIUULd11V 11. Hle uulven:s proposed on the_
facilities? No Yes, then provide full report documenting assumptions
criteria, analysis, computer programs, and study findings that support proposed
design(s). Is report provided? Yes —No If "no", explain:
Arterial or Maior Collector Streets: Will culverts serve these types of roadways?
No Yes How many instances? For each identify the
location and provide the information below.
Instance 1:
Instance 2:
Instance 3:
Yes or No for the 100-year design flow: 1 I 2 I 3
Headwater WSE 1 foot below lowest curb top?
Spread of headwater within ROW or easement?
Is velocity limited per conditions (Table C-11)?
Explain any "no" answer(s):
minor collector or Local streets: vvw culverts serve
No Yes How many instances? _
location and provide the information below:
Instance 1:
Instance 2:
Instance 3:
for each identify the
For each instance enter value, or "yes" / "no" for: 1 2 3
Design yr. headwater WSE 1 ft. below curb top?
100-yr. max. depth at street crown 2 feet or less?
Product of velocity (fps) & depth at crown (ft) = ?
Is velocity limited per conditions (Table C-11)?
Limit of down stream analysis (feet)?
Explain any "no" answers
STORMWATER DESIGN GUIDELINES Page 20 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.12)
Stormwater Management Concept (continued)'
Within Or Serving Subject Property (Phase, or Site) (continued)
All Proposed Culverts: For all proposed culvert facilities (except driveway/roadside
ditch intersects) provide information requested in next eight boxes.
Do culverts and travelways intersect at 90 degrees? _ Yes No If not,
identify location(s) and intersect angle(s), and justify the design(s):
Does drainage way alignment change within or near limits of culvert and surfaced
approaches thereto? No —Yes If "yes' identify location(s), describe
change(s), and justification:
Are flumes or conduit to discharge into culvert barrel(s)? No _ Yes If yes,
identify location(s) and provide justification:
Are flumes or conduit to discharge into or near surfaced approaches to culvert ends?
No Yes If "yes" identify location(s), describe outfall design treatment(s):
c
0
U
V)
W
>
Is scour/erosion protection provided to ensure long term stability of culvert structural
�j
components, and surfacing at culvert ends? Yes —No If "no" Identify
locations and provide justification(s):
Will 100-yr flow and spread of backwater be fully contained in street ROW, and/or
drainage easements/ ROW? _ Yes _ No if not, why not?
Do appreciable hydraulic effects of any culvert extend downstream or upstream to
neighboring land(s) not encompassed in subject property? No Yes If
"yes" describe location(s) and mitigation measures:
Are all culvert designs and materials in compliance with B-CS Tech. Specifications?
Yes _ No If not, explain in Special Design Section of this Part.
STORMWATER DESIGN GUIDELINES Page 21 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised Aucust 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.13)
Stormwater Management Concept (continued),,
Within Or Serving Subject Property (Phase, or Site) (continued)
Is a bridge included in plans for subject property project? ✓ No _ Yes
If "yes" provide the following information.
Name(s) and functional classification of the roadway(s)?
What drainage way(s) is to be crossed?
ti
m
m`
Afull report supporting all aspects of the proposed bridge(s) (structural, geotechnical,
hydrologic, and hydraulic factors) must accompany this summary report. Is the report
provided? _ Yes _ No If "no" explain:
Is a Stormwater
Provide a general description of planned techniques:
Pollution Prevention
sidtfence installation and inletprotection
6
Plan (SW3P)
a
established for
Q)
project construction?
m
No ✓ Yes
Special Designs — Non -Traditional Methods
Are any non-traditional methods (aquatic echosystems, wetland -type detention, natural stream
replication, BMPs for water quality, etc.) proposed for any aspect of subject property project?
✓ No _ Yes If "yes" list general type and location below.
Provide full report about the proposed special design(s) including rationale for use and
expected benefits. Report must substantiate that Stormwater management objectives will not
be compromised, and that maintenance cost will not exceed those of traditional design
solution(s). Is report provided? Yes _ No If "no" explain:
STORMWATER DESIGN GUIDELINES Page 22 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters Continued (Page 4.14)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Special Designs — Deviation From B-CS Technical Specifications
If any design(s) or material(s) of traditional runoff -handling facilities deviate from provisions of
B-CS Technical Specifications, check type facility(ies) and explain by specific detail element.
Detention elements Drain system elements Channel features
Culvert features Swales Ditches Inlets _Outfalls
Valley gutters Bridges (explain in bridge report)
In table below briefly identify specific element, justification for deviation(s).
Specific Detail Element
Justification for Deviation (attach additional sheets if needed)
1)
2)
3)
4)
5)
Have elements been coordinated with the City Engineer or her/his designee? For each item
above provide "yes" or "no", action date, and staff name:
1)
2)
3)
4)
5)
>. Design Parameters
Hydrology
Is a map(s) showing all Design Drainage Areas provided? ✓ Yes No
Briefly summarize the range of applications made of the Rational Formula:
Pipe Design, Inlet Design and Gutter Depth Check
What is the size and location of largest Design Drainage Area to which the Rational Formula
has been applied? 1.20 acres Location (or identifier): 201
STORMWATER DESIGN GUIDELINES Page 23 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.15)
Design Parameters (continued)
Hydrology (continued)
In making determinations for time of concentration, was segment analysis used?
—No ✓ Yes In approximately what percent of Design Drainage Areas? 100 %
As to intensity -duration -frequency and rain depth criteria for determining runoff flows, were any
criteria other than those provided in these Guidelines used? ✓ No _Yes If "yes"
identify type of data, source(s), and where applied:
For each of the stormwater management features listed below identify the storm return
frequencies (year) analyzed (or checked), and that used as the basis for design.
Feature
Analysis Year(s)
Design Year
Storm drain system for arterial and collector streets
N/A
N/A
Storm drain system for local streets
10 & 100
100
Open channels
N/A
N/A
Swale/buried conduit combination in lieu of channel
N/A
N/A
Swales
N/A
N/A
Roadside ditches and culverts serving them
N/A
N/A
Detention facilities: spillway crest and its outfall
N/A
N/A
Detention facilities: outlet and conveyance structure(s)
N/A
N/A
Detention facilities: volume when outlet plugged
N/A
N/A
Culverts serving private drives or streets
N/A
N/A
Culverts serving public roadways
N/A
N/A
Bridges: provide in bridge report.
N/A
N/A
Hydraulics
What is the range of design flow velocities as outlined below?
Design flow velocities;
Gutters
Conduit
Culverts
Swales
Channels
Highest (feet per second)
4.17
7.90
N/A
N/A
N/A
Lowest (feet per second)
1.15
1.50
N/A
N/A
N/A
Streets and Storm Drain Systems Provide the summary information outlined below:
Roughness coefficients used: For street gutters: 0.018
For conduit type(s) RCP HDPE Coefficients: 0.013 0.013
STORMWATER DESIGN GUIDELINES Page 24 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D —TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters
Continued (Page 4.16)
Design Parameters (continued),
Hydraulics (continued)
Street and Storm Drain Systems (continued)
For the following, are assumptions other than allowable per Guidelines?
Inlet coefficients? ✓ No _ Yes Head and friction losses ✓ No —Yes
Explain any "yes" answer:
In conduit is velocity generally increased in the downstream direction? ✓ Yes _ No
Are elevation drops provided at inlets, manholes, and junction boxes? ✓ Yes _ No
Explain any "no" answers:
Are hydraulic grade lines calculated and shown for design storm? ✓ Yes _ No
For 100-year flow conditions? ✓ Yes _ No Explain any "no" answers:
What tailwater conditions were assumed at outfall point(s) of the storm drain system? Identify
each location and explain:
Yes, the storm drain system was designed taking into account the detention pond being full.
Open Channels If a HEC analysis is utilized, does it follow Sec VI.F.5.a? _ Yes _ No
Outside of straight sections, is flow regime within limits of sub -critical flow? _ Yes _ No
If "no" list locations and explain:
Culverts If plan sheets do not provide the following for each culvert, describe it here.
For each design discharge, will operation be outlet (barrel) control or inlet control?
Entrance, friction and exit losses:
Bridges Provide all in bridge report
STORMWATER DESIGN GUIDELINES Page 25 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 4 — Drainaae Concept and Design Parameters
Continued (Page 4.17)
Design Parameters (continued)
Computer Software
What computer software has been used in the analysis and assessment of stormwater
management needs and/or the development of facility designs proposed for subject property
project? List them below, being sure to identify the software name and version, the date of the
version, any applicable patches and the publisher
Excel spreadsheets, Ardodesk Civil3D Storne Sewer Analysis and Hydroflow
Part 5 — Plans and Specifications
Requirements for submittal of construction drawings and specifications do not differ due to use of a
Technical Design Summary Report. See Section III, Paragraph C3.
Part 6 — Conclusions and Attestation
Conclusions
Add any concluding information here:
The storm sewer system and detention facilities are designed in
accordance with the BCS Drainage Design Guidelines.
���Attestatron
Provide attestation to the accuracy and completeness of the foregoing 6 Parts of this Technical
Design Summary Drainage Report by signing and sealing below.
"This report (plan) for the drainage design of the development named in Part B was prepared
by me (or under my supervision) in accordance with provisions of the Bryan/College Station
Unified Drainage Design Guidelines for the owners of the property. All licenses and permits
required by any and all state and federal regulatory agencies for the propo;i@4"gr�a�' nage
improvements have been issue or fall under applicable general permits."®P G OP �F@,9
(Affix Seal)
10
�d °k
Lice ed Professional Engineer JOSEPH aP ° SCHULTZ °�
0. 6q
State Texas PE J u� �Q��SS
of No. ? _ o?S oS�a°�
STORMWATER DESIGN GUIDELINES Page 26 of 26 APPENDIX. D: TECH, DESIGN SUMMARY
Effective February 2007 As Revised August 2012
Addendum to
Drainage Report
for
Spring Creek Townhomes, Phase 3
College Station, Texas
August 2013
Owner/Developer:
Spring Creek CS Development, Ltd.
4490 Castlegate Drive
College Station, Texas 77845
(979)690-7250
Prepared By:
Schultz Engineering, LLC
TBPE Firm No. 12327
P.O. Box 11995
College Station, TX 77842
2730 Longmire Drive, Suite A
College Station, Texas 77845
(979)764-3900
5CHULTZ ENGINEERING, LLC;
5
Drainage Report — Addendum — August, 2013
Spring Creek Townhomes, Phase 3
College Station, Texas
ENGINEER
SCHULTZ ENGINEERING, LLC.
P.O. Box 11995
College Station, Texas 77842
Phone: (979) 764-3900
Fax: (979) 764-3910
Spring Creek CS Development, Ltd.
3302 General Parkway
College Station, TX 77845
Phone: (979) 690-5000
ADDENDUM 1
There was a calculation error in the original report (Drainage Report for Spring Creek Townhomes, Phase 3, July
2013). The 10-year peak flow for Pipe 6 is 4.20 cfs, and the 100-yr peak flow is 5.25 cfs. These flows result in a
4.29 fps and 5.25 fps velocity for the 10-year & 100-year evens, respectively. An addendum to the drainage report is
included in this submittal.
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