HomeMy WebLinkAboutDrainage Report Drainage Report
for
The Barracks II Subdivision Phases 107
College Station, Texas
October 2014
Owner/Developer:
Heath Phillips Investments, LLC
3302 General Parkway
College Station, TX 77845
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
I .
• Drainage Report—Executive Summary
. The Barracks II Subdivision, Phases 107
. College Station,Texas
S
ENGINEER
• SCHULTZ ENGINEERING,LLC.
P.O.Box 11995
College Station,Texas 77842
Phone: (979)764-3900
Fax:(979)764-3910
OWNER/DEVELOPER
Heath Phillips Investments,LLC
3302 General Parkway
College Station,TX 77845
Phone: (979)690-5000
GENERAL DESCRIPTION AND LOCATION
I . This project consists of the development of Phase 107 of the Barracks II Subdivision in College Station. Phase 107
is a townhouse residential development,which will include the construction of utility and roadway infrastructure.
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I ill Location: Phase 107 is located northeast of Phase 106 and northwest of Phase 108 of the
Barracks II Development. The Barracks II Subdivision is a 108-acre
+ "* development located midway between Rock Prairie Road and Cain Road in
3 . south College Station. It is bounded on the west by Holleman Drive South and
on the east by Old Wellborn Road.
- Description:
• Area: 7.654 Acres
® ■ Proposed Land Use: Townhouse Residential
+ rti.r
• #of Lots: 63 lots
■ Existing Land Use: Vacant
I • • Land Description: The terrain slopes generally towards the north.
Primary Drainage Facility: Tributary B.3 of Bee Creek
Flood Hazard Information:
FEMA FIRM: #48041C0305F,Dated April 2,2014
Floodplain: None of this phase of the development lies within the floodplain.
HYDROLOGIC CHARACTERISTICS
The existing site is cleared. The elevations range from 303 to 299,sloping generally in a northerly direction. The
majority of the runoff will be directed to the roadways and the proposed storm sewer system and will discharge into
Old Wellborn Road roadside ditch. The stormwater detention facility drainage report prepared by Kimley-Hom has
been revised to evaluate the proposed drainage of the site and to address the increase in peak flow resulting from this
development.The remaining runoff will be directed to the roadways and the proposed storm sewer system and will
discharge into the existing detention facilities on Lot 1,Block 28 Phase 300 of The Barracks II Subdivision.
Ultimately,this runoff flows into Tributary B.3 of Bee Creek.
GENERAL STORMWATER PLAN
The drainage plan for this development will involve the installation of storm sewer pipes and inlets,which will
collect and convey a portion of the runoff into the existing storm sewer system and then to the existing detention
pond. This development will also discharge into the existing drainage ditch along Old Wellborn Road which will
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collect and convey the runoff downstream. The runoff that is collected by the existing detention ponds and the Old
Wellbom Road ditch will be discharged into tributary B.3 of Bee Creek.
• The detention pond analysis and design for this phase is covered under the drainage report titled,"The Barracks
Detention Facility Design City of College Station,Texas,Dated July 2012"prepared by Kimley-Hom and as
modified in September 2013 and as revised in the report submitted in September 2014.This revised report will take
into account the development of the adjacent tract to the north which has been acquired and will become part of the
Barracks.
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COORDINATION&STORMWATER PERMITTING
This project has 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 107 of the subdivision will be collected by a
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
two Exhibit A & B. Refer to Exhibit B for the locations of the inlets and storm
I • sewer pipes.
Street Design: Kimber Lane:
. Standard Cross-Section(3%cross-slope,27' B-B Residential Roadway)
Lay down and standard curb and gutter on residential streets
Deacon Drive:
Collector Street Cross-Section(3%cross-slope,48' B-B)
+e Standard Curb and gutter
Concrete Pavement
Standard recessed curb inlets(5' &10'in length)
lei® T',Methodology: TR 55
® Tc Minimum: 10 Minutes
law 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
Mannings n Values: 0.013 for pipes
0.018 for Streets
Runoff Coefficients: 0.75 for developed lotstot .
0.45 for undeveloped land
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Design Constraints: depth Max. water d th 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)
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. 25%reduction of cross-sectional area of pipes less than 24"in diameter
Min. 1' 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.
4111
• The software was used to compute pipe capacities, flow rates and velocities,
compute hydraulic grade line elevations, headwater elevations, gutter depth &
inlet sizing.
111 The requirement for a 25% reduction in cross sectional area of pipes 24" in
- diameter or less 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
a.r 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.
Detention Analysis: Runoff from the Barracks II Subdivision was previously studied and detention
ponds were designed for the entire development including this phase. See the
drainage report titled, "The Barracks Detention Facility Design City of College
oink Station, Texas, Dated July 2012" and as modified in September 2013 and by a
revised design being prepared by Kimley-Horn submitted in September 2014.
Sheet 05, "Proposed Condition Drainage Area Map", from the Kimley-Horn
September 2014 "Modifications to The Barracks Detention Facility" design
shows Drainage Area Cl, 18.56 acres of the project area discharging into the
Old Wellborn Road right of way. With the final design of Phase 107 and 108
the computed area discharging into the Old Wellborn Road right of way is 18.56
• acres. Since this matches the area shown by Kimley-Horn the existing detention
facilities for The Barracks are adequate for this phase of the subdivision and no
additional pond construction or modifications are necessary.
• Applicable Exhibits: Exhibit A—Drainage Area Map
ID Exhibit B—Drainage Plan
Appendix Al—Drainage Area Summary
Appendix Bl—Depth of Flow in Gutter
L Appendix B2—Storm Sewer Inlet Summary
Appendix C1—Storm Sewer Pipe Summary
Appendix D—Technical Design Summary
c CONCLUSION
The storm sewer,inlets&channel drainage system for Phase 107 of the Barracks II Subdivision will function within
the requirements and restrictions of the BCS Design Guidelines. The existing detention facilities are adequate for
this phase of the subdivision and no additional pond construction or modifications are necessary
I
CERTIFICATION
• I,Joseph P. Schultz,Licensed Professional Engineer No. 65889,State of Texas,certify that this report for the
• drainage design for The Barracks II,Phase 107,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 been
• issued.
111• r
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• Josept . Sct ultz,P.E.
• .fir
JOSEPH P. SCHULTZ
• an. 65889; •
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SCHULTZ ENGINEERING, U.0
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EXHIBIT A
DRAINAGE AREA MAP
EXHIBIT B
DRAINAGE PLAN
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APPENDIX Al
DRAINAGE AREA SUMMARY
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APPENDIX Al
Barracks II Phases 107
Drainage Area Summary
10 year storm 100 year storm
Area,A C tc
Area# lie Qio 1100 Qin
(acres) (min) (in/hr) (cfs) (in/hr) (cfs)
700 0.85 0.75 10.0 8.635 5.50 11.639 7.42
700A 0.49 0.75 10.0 8.635 3.17 11.639 4.28
700B 0.36 0.75 10.0 8.635 2.33 11.639 3.14
701 0.39 0.75 10.0 8.635 2.53 11.639 3.40
701A 0.28 0.75 10.0 8.635 1,81 11.639 2.44
701B 0.10 0.75 10.0 8.635 0.65 11.639 0.87
702 0.59 0.75 10.0 8.635 3.82 11.639 5.15
702A 0.35 0.75 10.0 8.635 2.27 11.639 3.06
702B 0.24 0.75 10.0 8.635 1.55 11.639 2.10
703 0.27 0.75 10.0 8.635 1.75 11.639 2.36
703A 0.11 0.75 10.0 8.635 0.71 11.639 0.96
SD 703B 0.17 0.75 10.0 8.635 1.10 11.639 1.48
704 0.85 0.75 10.0 8.635 5.50 11.639 7.42
IlD 704A 0.34 0.75 10.0 8.635 2.20 11.639 2.97
704B 0.51 0.75 10.0 8.635 3.30 11.639 4.45
0 705 0.41 0.75 10.0 8.635 2.66 11.639 3.58
0 706 1.00 0.65 10.0 8.635 5.61 11.639 7.57
0 707 1.35 0.75 10.0 8.635 8.74 11.639 11.78
1110 707A 0.94 0.75 10.0 8.635 6.09 11.639 8.21
707B 0.41 0.75 10.0 8.635 2.66 11.639 3.58
0 708 0.51 0.75 10.0 8.635 3.30 11.639 4.45
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708A 0.27 0.75 10.0 8.635 1.75 11.639 2.36
708B 0.24 0.75 10.0 8.635 1.55 11.639 2.10
hill
709 1.31 0.75 10.0 8.635 8.48 11.639 11.44
li - 709A 0.87 0.75 10.0 8.635 5.63 11.639 7.59
ID 709B 0.44 0.75 10.0 8.635 2.85 11.639 3.84
III 710 0.54 0.75 10.0 8.635 3.50 11.639 4.71
711 0.40 0.75 10.0 8.635 2.59 11.639 3.49
€ 712 0.26 0.75 10.0 8.635 1.68 11.639 2.27
Ili 713 0.16 0.75 10.0 8.635 1.04 11.639 1.40
III
The Rational Method:
Q=CIA I=b/(tc+d)e tc=L/(V*60)
Q=Flow(cfs) tc=Time of concentration(min) L=Length(ft
A=Area(acres) V=Velocity(ft/sec)
C=Runoff Coeff.
I=Rainfall Intensity(in/hr)
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• APPENDIX B1
• DEPTH OF FLOW IN GUTTER
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• APPENDIX B2
• STORM SEWER INLET SUMMARY
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APPENDIX B2
Barracks II Phases 107
Storm Sewer Inlets on Grade - Design Analysis
Inlet Length Street Q10 L10, ft. Bypass Q100 L100, ft. Bypass
No. ft. Slope cfs Design cfs cfs Design cfs
S710 10 1.01% 2.66 11.19 0.05 3.58 12.88 0.24
S711 10 0.60% 5.61 13.61 0.52 7.57 15.66 1.21
Assume 10%clogging for design
Se =Sx+ (a/w)* Eo
Eo= Qw/Q= 1 - [ 1 -W/T]2.67
L=Kc*Q0.47*So3*(1/(n*Se))0.6
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
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• APPENDIX Cl
STORM SEWER PIPE SUMMARY
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• APPENDIX D
• TECHNICAL DESIGN SUMMARY
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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
O completed. These are provided so that they may be copied and completed or scanned and
II 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
O Part 4— Drainage Concept and Design Parameters
Part 5— Plans and Specifications
lb Part 6—Conclusions and Attestation
rr
• 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
il 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,
ft 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.
6. 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.
7. 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 Professionals Information
Engineering Firm Name and Address: Jurisdiction
Schultz Engineering,LLC City: Bryan
- P.O.Box 11995 ✓ College Station
College Station, Tx 77842 Date of Submittal:
August 2014
Lead Engineer's Name and Contact Info.(phone, e-mail,fax): Other:
IR Joseph P. Schultz,PE email:joeschultz84@verizon.net
Phone: 764-3900 fax: 764-3910
Supporting Engineering/Consulting Firm(s): Other contacts:
n/a
Developer/ Owner/Applicant Information
Developer/Applicant Name and Address: Phone and e-mail:
Heath Phillips Investments,LLC 979-690-5000
3302 General Parkway
College Station, TX 77845
Property Owner(s) if not Developer/ Applicant(&address): Phone and e-mail:
•
Project Identification
Development Name:The Barracks II Subdivision,Phases 107
• 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 8 of 13
Legal description of subject property (phase)or Project Area:
(see Section II, Paragraph B-3a)
1116
Crawford Burnett League,A-7
I 4 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 complete and on-going in the previous phases(Sections 103, 104, 105,106, 108&
300)
General Location of Project Area, or subject property(phase):
Between Old Welborn Road and Holleman Dr.South,North of Rock Prairie Road West and South of Cain
Rd
In City Limits? Extraterritorial Jurisdiction (acreage):
Bryan: acres. Bryan: College Station:
College Station: 7.654 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)
Project Identification (continued)
Roadways abutting or within Project Area or Abutting tracts, platted land, or built
subject property: developments:
Old Wellborn Rd The Barracks Section 106
Holleman Drive South
Named Regulatory Watercourse(s) &Watershed(s): Tributary Basin(s):
Bee Creek Trib B.3
Plat Information For Project or Subject Property (or Phase)
Preliminary Plat File#: 14-00900010 Final Plat File#: A'/A Date:June 2014
Name: THE BARRACKS II(PP) Status and Vol/Pg: submitted with this project
If two plats, second name: File#:
Status: Date:
Zoning Information For Project or 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 Project or Subject Property (or Phase)
Planning Conference(s)& Date(s): Participants:
N/A
Preliminary Report Required? N/A 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 Project or Subject Property (or Phase)
Note: For any Coordination of stormwater matters indicated below, attach documentation
describing and substantiating any agreements, understandings, contracts, or approvals.
Coordination
Dept. Contact: Date: Subject:
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 ✓
Coordination with Summarize need(s) &actions taken (include contacts &dates):
TxDOT Needed?
Yes No411 ✓
Coordination with Summarize need(s) & actions taken (include contacts&dates):
- TAMUS Needed?
Yes No ✓
4 Permits For Project or 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 in spaces below.
EntityPermitted or Status of Actions (include dates)
Approved ?
US Army Crops of Permitted Permit approve&
Engineers
No Yes ✓
US Environmental
Protection Agency
No ✓ Yes
Texas Commission on Approved NOI for entire Subdivision
Environmental Quality
No Yes ✓
Brazos River
Authority
No if Yes
STORMWATER DESIGN GUIDELINES Page 5 of 26 APPENDIX. D:TECH. DESIGN SUMMARY
IEffective 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=75%
Redevelopment of one platted lot, or two or more adjoining platted lots.
Site
Development Building on a single platted 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 platted 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.
Describe Subdivisions: number of lots by general type of use, linear feet of streets and
Nature and drainage easements or ROW.
Size of 63 lots. Approximately 1890'of Streets.
Proposed
Project 2.24 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?
Encroachment(s) 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
✓ Kimley-Horn Study(July 2012&Revised September 2013)-Analyzed downstream flooding
potential and detention pond design.
Is the stormwater management plan for the property in substantial conformance with the
earlier study? Yes_ ✓ _ No_ _ If not, explain how it differs.
No If subject property is not part of multi-phase project, describe stormwater management
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, outfall, model, etc).
Any known drainage or flooding problems in areas near subject property? No ✓ Yes
• Identify:
• The area around Cain Road and Old Wellborn Road.
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 previous phase
✓ Detention is required. Need must be evaluated. Detention not required.
II What decision has been reached? By whom?
If the need for How was determination made?
Type 1 Detention
must be evaluated:
I
STORMWATER DESIGN GUIDELINES Page 7 of 26 APPENDIX. D:TECH.As Rev DESIGNed SUMMARY
Effective February 2007
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 3 — Property Characteristics Continued (Page 3.3)
Hydrologic Attributes of Subject Property (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 II, Paragraph B3-a)
Does Project Area (project or phase) receive runoff from upland areas? No ✓ Yes
Size(s)of area(s)in acres: 1) 2.52 2) 3) 4)
Flow Characteristics(each instance)(overland sheet, shallow concentrated, recognizable
concentrated section(s), small creek(non-regulatory), regulatory Watercourse or tributary);
Each instance is overland sheet flow and shallow concentrated flow.
Flow determination: Outline hydrologic methods and assumptions:
Rational Equation. C-values
0.75 for Developed Lot Areas, 0.65 for Developed Park Areas, 0.45 for Undeveloped Areas
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
Yes.As adjoining tracts develop and install detention ponds,their outflows will be conveyed through
this tract by the proposed storm sewer.
Conveyance Pathways (Section II, 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.As Revised DESIGN SUMMARYugust
Effective February 2007
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 3 — Property Characteristics Continued (Page 3.4)
Hydrologic Attributes of Subject Property (or Phase) (continued)
Conveyance Pathways (continued)
Do drainage If yes, for what part of length? % Created by? 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?)
Existing watercourse crosses the downstream properties.See Kimley Horn Report
Pathway
Areas
Describe any built or improved drainage facilities existing near the property (culverts,
bridges, lined channels, buried conduit, swales, detention ponds, etc).
Detention Ponds constructed with previous phases.
Nearby
Drainage Do any of these have hydrologic or hydraulic influence on proposed stormwater
Facilities
design? No / Yes If yes, explain:
See Kimley Horn Report,Phase 100 Report by Phillips Engineering and Phases 101-104&
300 Report by Goodwin-Lasiter,Inc.
•
•
•
•
•
11111,
1 STORMWATER DESIGN GUIDELINES Page 9 of 26 APPENDIX. D:TECH. DESIGN SUMMARY
s
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.
Runoff from upland areas will be captured in publicly owned storm drain systems as the subdivision
develops.
Discharge(s)To Lower Property(ies) (Section II, Paragraph El)
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#
Detention Pond.
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.As RevisedN SUMMARY
Effective February 2007
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4— Drainage Concept and Design Parameters Continued (Page 4.2)
Stormwater 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 Project Area (type&location of facilities): (Attached Exhibit#A
Existing detention ponds will serve the proposed development.
it,
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..
•ID c >- Are other Best Management Practices for reducing stormwater pollutants proposed?
co
b_ No ✓ Yes Summarize type of BMP and extent of use:
tr
Silt fences, construction exits, rock check dams,seeding and erosion matting.
a) o
z
If design of any runoff-handling facilities deviate from provisions of B-CS Technical
a✓ Specifications, check type facility(ies)and explain in later questions.
co Detention elements Conduit elements Channel features
N
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 ponds constructed with the previous phases will serve this phase. Runoff will enter the
pond through the underground storm drains.
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?
�• V-Channel Grass Lined
a; rn Steepest side slopes: Usual front slopes: Usual back slopes:
>- 2:1 2:1 4:1
1 Flow line slopes: least 1.00 Typical distance from travelway:
a) typical 1.00 greatest 5.00
(Attached Exhibit#B
-a 0
z
CD
• 2 Are longitudinal culvert ends in compliance with B-CS Standard Specifications?
I Yes No, then explain:
Q
c, At intersections or otherwise, do valley gutters cross arterial or collector streets?
I No Yes If yes explain:
U -C3
uAre valley gutters proposed to cross any street away from an intersection?
io I No Yes Explain: (number of locations?)
'� z
STORMWATER DESIGN GUIDELINES Page 12 of 26 APPENDIX. D:TECH.As Revised SUMMARY
Effective February 2007
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters Continued (Page 4.4)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site)(continued)
Gutter line slopes: Least 0.60 Usual 0.60 Greatest 1.01
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)
D Will inlet size and placement prevent exceeding allowable water spread for 10-year
design storm throughout site(or phase)? ✓ Yes No If no, explain.
Y
0)
'' S Sagcurves: Are inlets placed at low points? ✓ Yes �f No Are inlets and
- E conduit sized to prevent 100-year stormflow from ponding at greater than 24 inches?
0 o✓ Yes No Explain "no" answers.
a)
El?.
71;
22 Will 100-yr stormflow be contained in combination of ROW and buried conduit on
Q 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.
limo Are any 12-inch laterals used? ✓ No Yes Identify length(s) and where
- used.
ID -.
a) Pipe runs between system Typical 135' Longest 809'
- access points(feet):
- ,r,✓ Are junction boxes used at each bend? ✓ Yes No If not, explain where
and why.
c
to (1 z
o
-
• E
Are downstream soffits at or below upstream soffits? Least amount that hydraulic
a) Yes ✓ No If not, explain where and why: grade line is below gutter line
(system-wide):
0.71' (10-Yr Storm)
STORMWATER DESIGN GUIDELINES Page 13 of 26 APPENDIX. D:TECH.As RevisedN SUM 1ARY
2012
Effective February 2007
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters Continued (Page 4.5)
Stormwater Management Concept (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
1) Watercourse (or system), velocity, and angle?
Bee Creek Trib B.3 @ 0°,<2 fps
E 2) Watercourse (or system),velocity, and angle?
O
p
o
E - 3)Watercourse (or system), velocity, and angle?
� -a 0
L 0
Q
E -- For each outfall above, what measures are taken to prevent erosion or scour of
o r receiving and all facilities at juncture?
1) Outfall from this development will occur into downstream pipes from prey.phases
L
cu
2)
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):
�.
411 cn
a�
} Flow line slopes(minimum and maximum):
•
4111
o
NZ Outfall characteristics for each (velocity, convergent angle, &end treatment).
c�a✓
co
co
2
Will 100-year design storm runoff be contained within easement(s)or platted drainage
ROW in all instances? Yes No If"no" explain:
4 0
STORMWATER DESIGN GUIDELINES Page 14 of 26 APPENDIX. D:TECH.As RevisedN SUMMARY
Effective February 2007
SECTION IX
APPENDIX D - TECHNICAL DESIGN SUMMARY
Part 4— Drainage Concept and Design Parameters Continued (Page 4.6)
Stormwater Management Concept (continued)
Within Or Serving Subject Property(Phase, or Site)(continued)
Are roadside ditches used? No I Yes If so, provide the following:
LIs 25-year flow contained with 6 inches of freeboard throughout ? .1 Yes No
1-2 Are top of banks separated from road shoulders 2 feet or more? Yes I No
a)
Are all ditch sections trapezoidal and at least 1.5 feet deep? Yes I No
For any"no"answers provide location(s)and explain:
cn
oThe existing ditch along Old Welborn Road is a V-Channel that does not allow for the ditch to
• be trapezoidal or to be separated from the road shoulders.
If conduit is beneath a swale, provide the following information (each instance).
Instance 1 Describe general location, approximate length:
>- Is 100-year design flow contained in conduit/swale combination? Yes No
If "no" explain:
O
o co Space for 100-year storm flow? ROW Easement Width
z c Swale Surface type, minimum Conduit Type and size, minimum and maximum
1/ c and maximum slopes: slopes, design storm:
0
co -0
T) al Inlets Describe how conduit is loaded (from streets/storm drains, inlets by type):
O 0
c� @
s
O
0. o Access Describe how maintenance access is provided (to swale, into conduit):
o :
c�
. o
• L
a - o
--a)
, Instance 2 Describe general location, approximate length:
. 7
a� coE
411 z
Is 100-year design flow contained in conduit/swale combination? Yes No
411 0
o If "no" explain:
411 �
E Space for 100-year storm flow? ROW Easement Width
U
0 Swale Surface type, minimum Conduit Type and size, minimum and maximum
410
5 co and maximum slopes: slopes, design storm:
C CO
aInlets Describe how conduit is loaded (from streets/storm drains, inlets by type):
3 0
Access Describe how maintenance access is provided (to swale, into conduit):
(
STORMWATER DESIGN GUIDELINES Page 15 of 26 APPENDIX. D:TECH.As Revised DESIGN SUMMAugust RY
Effective February 2007
SECTION IX
APPENDIX D — TECHNICAL DESIGN SUMMARY
Part 4 — Drainage Concept and Design Parameters Continued (Page 4.7)
Stormwater Management Concept(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:
Co.
n.
E w
Is 100-year design flow contained in swale? Yes No Is swale wholly
o• >_ within drainage ROW? Yes No Explain "no" answers:
W
)
v Access Describe how maintenance access is provide:
o
Z
0
Instance 2 Describe general location, approximate length, surfacing:
m
o E
3 m Is 100-year design flow contained in swale? Yes No Is swale wholly
m �' within drainage ROW? Yes No Explain "no" answers:
o
O
c Access Describe how maintenance access is provided:
.U_
Q
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.
Will design replicate natural channel? Yes No If"no", for each instance
3 describe section shape &area, flow line slope(min. &max.), surfaces, and 100-year
wdesign flow, and amount of freeboard:
o_ Instance 1:
• • o
a�
E
m
r o Instance 2:
a
E o
� z
I • E ✓ Instance 3:
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)
a
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
°) existing and proposed section size and shape, surfaces, alignment,flow line changes,
length affected, and capacity, and provide full documentation of analysis procedures
° and data. Is full report submitted? Yes No If"no" explain:
a
E
m
co All 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:
r
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:
a)
>-
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
-0' If"no"explain:
a)
U)
0
Q.
0
a For each, what is velocity of 25-yr design discharge at outlet? & at spillway?
a Facility 1: & Facility 2: &
F-
r) Are energy dissipation measures used? No Yes Describe type and
u_ location:
0
c
a)
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 Concept (continued)
Within Or Serving Subject Property(Phase, or Site)(continued)
Do structures comply with B-CS Specifications? Yes or no, and explain if"no":
a)
Facility 1;
a)
:62
5 Facility 2:
o c
o
U
iv For additional facilities provide all same information on a separate sheet.
0
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:
ui
oAre culverts parallel to public roadway alignment? Yes No Explain:
P
• Q Creeks at Private Drives: Do private driveways, drives, or streets cross drainage
• o ways that serve Above-Project areas or are in public easements/ ROW?
11111N z No Yes If"yes" provide information below.
,/ How many instances? Describe location and provide information below.
•
> Location 1:
• >
U
Location 2:
Location 3:
For each location enter value for: 1 2 3
0 Vs 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 SUMMARY
Part 4— Drainage Concept and Design Parameters Continued (Page 4.11)
Stormwater Management Concept(continued)
1111 Within Or Serving Subject Property (Phase, or Site)(continued)
Named Regulatory Watercourses (&Tributaries): Are culverts proposed on these
• 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:
ID
al Arterial or Major Collector Streets: Will culverts serve these types of roadways?
-c I No Yes How many instances? For each identify the
a location and provide the information below.
a a3 Instance 1:
>- a
°' Instance 2:
c
o Instance 3:
o
o m Yes or No for the 100-year design flow: 1 2 3
z E
`o Headwater WSE 1 foot below lowest curb top?
N Spread of headwater within ROW or easement?
E
y Is velocity limited per conditions(Table C-11)?
N Explain any"no" answer(s):
O c
C o
RS U
• o Minor Collector or Local Streets: Will culverts serve these types of streets?
n No Yes How many instances? for each identify the
location and provide the information below:
• Q. N
Instance 1:
411
0 c Instance 2:
• m
co o Instance 3:
cFor each instance enter value, or"yes"/"no"for: 1 2 3
;, y Design yr. headwater WSE 1 ft. below curb top?
• < .- 100-yr. max. depth at street crown 2 feet or less?
• E 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 2012
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)
ID 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):
0
Does drainage way alignment change within or near limits of culvert and surfaced
m-- 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
- o
1111
> Is scour/erosion protection provided to ensure long term stability of culvert structural
4111
components, and surfacing at culvert ends? Yes No If"no" Identify
- locations and provide justification(s):
411
•
- 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?
i
Do appreciable hydraulic effects of any culvert extend downstream or upstream to
iill neighboring land(s) not encompassed in subject property? No Yes If
"yes"describe location(s)and mitigation measures:
i
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 August 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?
a)
0
ML
W
A full 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 rock riprap,silt fence installation and inlet protection
To Plan (SW3P)
C� established for
project construction?
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?
I 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:
C
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)
L 5)
• Design Parameters
Hydrology
Is a map(s) showing all Design Drainage Areas provided? ✓ Yes No
S Briefly summarize the range of applications made of the Rational Formula:
- Pipe Design,Inlet Design and Gutter Depth Check
low
What is the size and location of largest Design Drainage Area to which the Rational Formula
has been applied? 4.64 acres Location (or identifier): 816
r ,
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 13/0
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 10& 100 10
Storm drain system for local streets 10& 100 10
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 NM
dO Culverts serving private drives or streets N/A NM
ID Culverts serving public roadways N/A N/A
Bridges: provide in bridge report. NM N/A
• Hydraulics
• What is the range of design flow velocities as outlined below?
ID Design flow velocities; Gutters Conduit Culverts Swales Channels
• Highest(feet per second) 3.18 9.12 N/A N/A N/A
Lowest(feet per second) 1.48 1.89 N/A N/A NM
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 I No Yes
Explain any"yes" answer:
In conduit is velocity generally increased in the downstream direction? I Yes No
Are elevation drops provided at inlets, manholes, and junction boxes? I Yes No
Explain any "no"answers:
Are hydraulic grade lines calculated and shown for design storm? ✓ Yes No
For 100-year flow conditions? I 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 a tail water of 292.0'.
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.
F For each design discharge, will operation be outlet(barrel)control or inlet control?
r
C
Entrance,friction and exit losses:
Bridges Provide all in bridge report
0••• 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 — Drainage 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,Autodesk Civil 3D Storm 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.
Attestation
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 izQ used drainage
improvements have been sued +r fall under applicable general per : oF: ? ,
4 .,_
ASIA (D.
(A
ffix Sealy'� ' � � �_
� ff (3
9 . F�® S��
I 1 ® EttV oo� 0 �..
1-7
Licensed 'rofessional Engineer ' l f ':' "
R
F; E
State of Texas PE No. 6.s"
ri�
!� `-��:
S6V
fi/0-f$7e . mss l Sy `� ( N:
STORMWATER DESIGN GUIDELINES Page 26 of 26 APPENDIX. D:TECH. DESIGN SUMMARY
Effective February 2007 As Revised August 2012