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Preliminary Drainage Report

Prime Consultant:

October 2010KHA Project # 098134000

Copyright © 2010, Kimley-Horn and Associates, Inc.

TABLE OF CONTENTSPRELIMINARY DRAINAGE REPORT

098134000 Grant Road Improvement PlanOctober 2010 i Preliminary Drainage Report

1. INTRODUCTION ............................................................................................................................. 21.1 Scope...................................................................................................................................... 21.2 Site Location and Project Description .................................................................................. 21.3 Previous Studies .................................................................................................................... 51.4 Long Term Maintenance Responsibility .............................................................................. 6

2. OFFSITE HYDROLOGY .................................................................................................................. 72.1 Existing Watersheds ............................................................................................................. 72.2 Precipitation .......................................................................................................................... 92.3 Soil Types .............................................................................................................................. 92.4 Land Use.............................................................................................................................. 102.5 FEMA Mapping .................................................................................................................. 102.6 Hydrologic Methodology .................................................................................................... 102.7 Existing Hydrologic Data (TSMS Node data) Review ....................................................... 112.8 Hydrologic Analysis and TSMS Comparison..................................................................... 112.9 Offsite Hydrologic Recommendations ................................................................................ 15

3. ONSITE ROADWAY HYDROLOGY................................................................................................ 16

4. OFFSITE HYDRAULICS ................................................................................................................ 204.1 Existing Offsite Storm Drain Hydraulics ........................................................................... 204.2 Offsite Street Hydraulics Methodology .............................................................................. 214.3 Existing Offsite Street Hydraulics ...................................................................................... 224.4 Proposed Offsite Street Hydraulics .................................................................................... 244.5 Combined Offsite Capacity (Storm Drain and Street) ....................................................... 264.6 Offsite Inlet Hydraulics and Median Curb Cuts ................................................................ 29

5. ONSITE HYDRAULICS ................................................................................................................. 315.1 Onsite Proposed Street Capacity ........................................................................................ 315.2 Onsite Proposed Inlet Hydraulics ....................................................................................... 345.3 Onsite Proposed Storm Drain Hydraulics .......................................................................... 36

6. SUMMARY AND CONCLUSION ..................................................................................................... 37

6. REFERENCES ............................................................................................................................... 39

APPENDICES....................................................................................................................................... 40


098134000 Grant Road Improvement PlanOctober 2010 ii Preliminary Drainage Report

LIST OF EXHIBITS

Exhibit 1-1 - Grant Road Improvement Plan, Study Area ...................................................................... 4Exhibit 1-2 – Inventory of Completed Drainage and Hydrology Studies ................................................ 5Exhibit 2-1 – Major Watersheds Contributing Areas ............................................................................. 8Exhibit 2-2 – Tucson Stormwater Management Study (TSMS) Nodes ................................................... 8Exhibit 2-3 – FEMA Floodplains Affecting Grant Road ...................................................................... 10Exhibit 2-4 – Summary of Hydrologic Analysis .................................................................................. 12Exhibit 2-5 – 100-Year Hydrologic Analysis Comparison Summary ................................................... 13Exhibit 2-6 – Summary of Recommended Offsite Discharges.............................................................. 15Exhibit 3-1 – Summary of Typical Onsite Flow Rate Per Unit Area .................................................... 16Exhibit 3-2 – Summary of Westbound Onsite Sub-basin Discharges.................................................... 17Exhibit 3-3 – Summary of Eastbound Onsite Sub-basin Discharges ..................................................... 18Exhibit 4-2 – Summary of Existing Storm Drain Capacities ................................................................ 20Exhibit 4-3 – Summary of Existing Street Capacities........................................................................... 22Exhibit 4-4 – Summary of Proposed vs Existing Street Capacities ....................................................... 24Exhibit 4-5 – Summary of Combined Proposed vs Existing Capacities ................................................ 26Exhibit 5-1 – Summary of Proposed Onsite Street Capacities .............................................................. 31Exhibit 5-2 – Summary of Westbound Onsite Pavement Hydraulics .................................................... 32Exhibit 5-3 – Summary of Eastbound Onsite Pavement Hydraulics ..................................................... 33Exhibit 5-4 – Summary of Westbound Inlet Hydraulics ....................................................................... 35Exhibit 5-5 – Summary of Eastbound Inlet Hydraulics ........................................................................ 36

Exhibit A-1 – Tucson Stormwater Management Study (TSMS) Nodes ................................. Appendix AExhibit A-2 – Soils Map ...................................................................................................... Appendix AExhibit A-3 – Aerial Photograph .......................................................................................... Appendix AExhibit A-4 – FEMA FIRM Panels ...................................................................................... Appendix AExhibit A-5 – Existing Offsite Watershed Map..................................................................... Appendix AExhibit A-6 – Drainage Onsite Sub-Basins Map ................................................................... Appendix AExhibit A-7 – 30% Storm Drain Plan and Profile .................................................................. Appendix A

LIST OF APPENDICES

Appendix A – Exhibit MapsAppendix B – Existing Hydrologic Data SheetsAppendix C – Proposed Hydrologic Data SheetsAppendix D – Offsite Storm Drain Hydraulics (Compact Disc)Appendix E – Existing Offsite Street Hydraulics (Compact Disc)Appendix F – Proposed Offsite Street Hydraulics (Compact Disc)Appendix G – Existing Offsite Inlet Hydraulics (Compact Disc)Appendix H – Proposed Offsite Inlet Hydraulics (Compact Disc)Appendix I – Offsite Median Curb Cut Hydraulics (Compact DiscAppendix I – Onsite Street Hydraulics (Compact Disc)Appendix J – Onsite Inlet Hydraulics (Compact Disc)Appendix K – Onsite Storm Drain Hydraulics (Compact Disc)


098134000 Grant Road Improvement PlanOctober 2010 iii Preliminary Drainage Report

ACRONYMS/ABBREVIATIONS

CFS Cubic Feet per SecondCIPPFEMA

Cast In Place PipeFederal Emergency Management Agency

GRIP Grant Road Improvement PlanHSG Hydrologic Soil GroupsNAVD North American Vertical DatumNRCS Natural Resources Conservation ServicePAG Pima Association of GovernmentsTSMS Tucson Stormwater Management StudyRCBRCPRTA

Reinforced Concrete BoxReinforced Concrete PipeRegional Transportation Authority

SQ. MI. Square miles

098134000 Grant Road Improvement PlanOctober 2010 1 Preliminary Drainage Report

The Grant Road Improvement Plan Preliminary Drainage Report has been prepared by Kimley-Hornand Associates, Inc. under the direct supervision of the following Registered Civil Engineer. Theundersigned attests to the technical data contained in this study, and to the qualifications of technicalspecialists providing engineering computations upon which the recommendations and conclusions arebased.

Registered Civil Engineer Date


1. INTRODUCTIONThe purpose of the Grant Road Improvement Plan Preliminary Drainage Report is to document thefindings of the hydrologic and hydraulic characteristics of the respective onsite and offsite watershedsand infrastructure affecting Grant Road between Oracle Road and Swan Road. This report will providea review of existing Tucson Stormwater Management Study (TSMS) data, roadway hydrologic data,and existing and proposed drainage infrastructure. This report serves as documentation of all the designflow rates tributary to the Grant Road Project that will be used to size the recommended drainageimprovements included in the roadway design.

1.1 Scope

The drainage analysis included the following tasks:

1. Obtain TSMS data from the City of Tucson, including HEC-1 models.2. Develop peak discharges for the 2-year, 10-year, and 100-year storm events for upstream

watersheds that are impacting Grant Road from Oracle Road to Swan Road.3. Compare peak discharges in task 2 with TSMS data and determine design flows for the project.4. Identify existing offsite and onsite drainage infrastructure within the project limits and analyze the

capacity of each drainage structure.5. Analyze capacity of existing and proposed roadway sections along corridor.6. Identify areas in which new storm drain facilities would improve drainage conveyance within

project limits. What are the project limits? You have identified east and west but not north andsouth

7. Identify capacity issues of existing drainage infrastructure that cannot be mitigated by this project.8. Identify areas of concern in regards to drainage improvements to be addressed with geometric

design alterations with roadway designers.9. Document the study approach, methods, results, findings and conclusions.10. Provide a drainage document and concept plans that outline a sequence to proceed through final

design and aid the City of Tucson in budgeting and scoping of future phases.

1.2 Site Location and Project Description

Grant Road lies within northeastern Pima County in Tucson, Arizona. Grant Road extends fromSilverbell Road on the west, to Tanque Verde/ Kolb Road on the east. Grant Road is a major regionalarterial that serves as a major access to Interstate 10 and to the University of Arizona.

The Regional Transportation Authority (RTA) Plan, approved by Pima County voters in May 2006,includes $166 million to widen Grant Road to six lanes from Oracle Road to Swan Road. As definedduring the RTA planning process, the project will include the addition of one new travel lane in eachdirection (six lanes total), as well as significant enhancements to the streetscape, landscape, transit,bicycle, and pedestrian facilities.

The City of Tucson initiated the Grant Road Improvement Plan (GRIP) to determine the futurealignment of Grant Road and to develop preliminary engineering design. Major components of theplanning effort include a roadway alignment plan, roadway and streetscape plan, and a land use andrevitalization plan.


The Grant Road Improvement Plan will direct long-term improvements to the functionality and urbanvitality of Grant Road in a manner that demonstrates "best practices" in multi-modal transportation andstreetscape design, pedestrian-oriented redevelopment and environmental sustainability. The Planconsiders opportunities to link neighborhoods to businesses along the corridor by foot, bike, and transit.

The Grant Road Improvement Plan will also include strategies to enhance the sustainability and vitalityof businesses and residential areas along Grant Road. The city desires the new Grant Road to be aunique place and to serve as a model for sustainable transportation and community development.

The project limits for the Grant Road Improvement Plan are from Oracle Road to Swan Road. Theproject is approximately five miles in length. The GRIP is intended to focus on Grant Road, but projectlimits sometimes extend a short distance north and south along cross streets when roadwayimprovements are required to tie the proposed intersections into existing cross street geometries. Thelocation of Grant Road and the project study area is shown in Exhibit 1-1.


Exhibit 1-1 - Grant Road Improvement Plan, Study Area


1.3 Previous Studies

Exhibit 1-2 lists completed studies that were reviewed by Kimley-Horn during the data collection phaseof the project. These studies were reviewed to identify existing drainage facilities and wash locations,as applicable to the Grant Road project. Findings from this existing studies review will be discussed inSection 2.

Exhibit 1-2 – Inventory of Completed Drainage and Hydrology Studies

StudyNumber Description Date Prepared By

1 Report on Alvernon Way Drainage Study -Phase II - Speedway to Fort Lowell April 6,1977

Laurence O. "Pat"Henry ConsultingEngineer

2Alvernon Way Roadway Improvements -Speedway to Grant - FinalHydrologic/Hydraulic and Storm Drain DesignReport

January 31, 1983 The SP Group

3 Columbus Wash Drainage Relief Project -Final Summary Report June 22, 1994 Cella Barr Associates

4 Columbus Wash Drainage Relief Project -LOMR June 6, 1996 Cella Barr Associates

5 Concept Design Report for Columbus WashDrainage Relief Project January 29, 1997 MMLA

6 Design Concept Report - Columbus WashDrainage Relief Improvements Phase II November 8, 2002 MMLA

7Final Hydrologic and Hydraulic Report -Columbus Wash Drainage Relief Project -Phase II

July 27, 1994 Cella Barr Associates

8 Drainage Report for Country Club Road -Glenn Street to Fort Lowell Road Project September 28, 1983 Simons, Li &

Associates, Inc.

8AAddendum to Drainage Report for CountryClub Road - Glenn Street to Fort Lowell RoadProject

November 18, 1983 Simons, Li &Associates, Inc.

9 Country Club Storm Sewer December 31, 1973Laurence O. "Pat"Henry ConsultingEngineer

10 Drainage Study Swan Road - SpeedwayBoulevard to Grant Road Unknown Gene Anderson

Engineering

11 Drainage Report for Swan Road Storm Sewer- Grant Road to Alamo Wash February 15, 1972 Francis R. Emmett

12 Concept Design Report for Mountain Avenue- Grant Road to Hendrick Drive May 2, 1994 MMLA, Inc.

13Report on Existing Conditions for MountainAvenue Storm Drainage Study - Part 1 StudyReport

September 30, 1988 CMG DrainageEngineering, Inc.


Exhibit 1-2 – Inventory of Drainage and Hydrology Studies (continued)

Description Date Prepared By

14Final Report on Evaluation of BasinManagement Alternatives and Development ofRecommended Plan for Mountain AvenueStorm Drainage - Part II Study Report

April 14, 1989 CMG DrainageEngineering, Inc.

15Preliminary Drainage Report for MountainAvenue Drainage Improvements - Grant Roadto Hedrick Drive

June 30, 1995 MMLA, Inc.

16Hydrology Report - Mountain Avenue DrainageImprovement, Phase I: Grant Road to HedrickDrive

July 8, 1993 Simon, Li &Associates, Inc.

17 Conceptual Drainage Outfall Plan - GrantRoad: Oracle Road to Park Avenue January, 2003

Parsons BrinckerhoffQuade & Douglas,Inc.

18Drainage Report "B" Drainage Design forSpeedway Boulevard - Euclid Avenue toTucson Boulevard

December 1987 Sverdrup Corporation

19Final Design Drainage Report for SpeedwayBoulevard - Tucson Boulevard to AlvernonWay

September 16, 1988 Johnson-Brittain &Associates, Inc.

20 Final Hydrologic and Hydraulic Investigationfor Sixth Avenue, Grant Road to Drachman May 1986 Johnson-Brittain &

Associates, Inc.

21 Final Hydrologic and Hydraulic Report forOracle Road - Drachman to Glenn Street February 1988 Greiner Engineering

22Report on Existing Conditions andDevelopment of Alternatives for Flowing WellsRoad and Glenn Street Drainage Relief Study

October 13, 1989 CMG DrainageEngineering, Inc.

23Drainage Report B - Drainage Design for FortLowell Road - Country Club Road to WalnutAvenue

April 1984 Sverdrup & Parceland Associates, Inc.

24 Goyette Avenue Drainage ImprovementsStudy - Grant Road to Glenn Street May 7, 1991 BRW, Inc.

1.4 Long Term Maintenance Responsibility

All existing drainage facilities and proposed drainage improvements for this project are and will beowned and maintained by the City of Tucson Transportation Department.


2. OFFSITE HYDROLOGYThe goal of the offsite hydrologic analysis is to provide a complete set of design flow rates to use for theGrant Road Improvement Plan project drainage improvement recommendations. Existing peak flowswere used where available, and supplemental calculations were completed for locations withoutacceptably documented flows.

2.1 Existing Watersheds

Project area watersheds are bound by the Santa Cruz River to the west and the Rillito River to the north.The project area’s general topography slopes from south to north with approximately 120 feet of verticalfall in some of the larger watersheds. There are six major offsite watersheds. Four watersheds(Christmas Wash, Alvernon Wash, Creekside Wash, and Swan Road Wash) intersect the project anddrain to the Rillito River to the north, while two watersheds (Grant Road Wash and Flowing WellsWash) drain to the west into the Santa Cruz River. The Grant Road Improvement Plan project limitsintersect these six major watersheds upstream from the ultimate discharge points (Rillito River andSanta Cruz River). Exhibit A-1 located in Appendix A provides a map showing each watershed andnode location.

The hydrology for the greater Tucson area has been studied in the Tucson Stormwater ManagementStudy with the resulting recommendations presented in “Phase II, The Stormwater Master Plan”(Simons, Li & Associates, 1992-1995). The study divided the project study area into six majorhydrologic units, or areas with similar geographic and hydrologic characteristics. These units were thenfurther subdivided into 59 watersheds. Depending on the size and drainage patterns, includingdevelopment and infrastructure, each watershed was divided into sub basins to provide flowconcentration points or nodes. The study area of the Grant Road Improvement Plan is located withintwo different hydrologic units: Flowing Wells/Tucson Arroyo, and Alamo/Christmas. Within these twounits, the watersheds of interest are Flowing Wells Wash, Grant Wash, Christmas Wash, AlvernonWash, and Swan Road Wash. The TSMS also identifies the major drainage washes along Grant Roadwhich include: Grant Road Wash, Mountain Avenue (street) Wash, Wilson Avenue (street) Wash,Midway Wash, Christmas Wash, Alvernon (street) Wash, Columbus Wash, Swan Road (street) Washand the many tributaries to these washes. Grant Road Wash is the only watercourse flowing east to westcompared to the predominate flow direction of south to north. Columbus Wash has the largest totalflow of the street washes. Columbus Wash originates north of Speedway Boulevard and combines withAlvernon Wash prior to the confluence with the Rillito River. Wilson Avenue Wash and MountainAvenue Wash both collect flow within the greater Flowing Wells Wash Drainage Area and outfall northof Grant Road at Rillito River. Swan Road Wash is the smallest watershed in contributing area, with aboundary beginning at Speedway Boulevard and extending north to the Rillito River.

Since the original TSMS study, there have been multiple revisions to the hydrology for specific areaswithin the TSMS. Exhibit 2-1 summarizes the major contributing watersheds to the project. Exhibit 2-2 lists the location of each node (concentration point) for areas contributing to and crossing Grant Road,and the corresponding 2-year, 10-year and 100-year discharges. Exhibit 2-2 includes a columnproviding the revision date to the original TSMS with which the corresponding discharges areassociated. For dates listed as draft, the revision has not yet been adopted and these flow rates are stillin the approval process by the City of Tucson. Exhibit A-1 located in Appendix A provides a mapshowing each watershed and node location.


Exhibit 2-1 – Major Watersheds Contributing Areas

Watershed Name Total Area (Acres) Grant Road TributaryArea (Acres) Ultimate Discharge

Grant Road Wash 416 203Santa Cruz River

Flowing Wells Wash 4341 995

Christmas Wash 2175 1114

Rillito River

Alvernon Wash 2050 1574

Swan Road Wash 316 60

Creekside Wash 357 222

Alamo Wash 6258 5843

Exhibit 2-2 – Tucson Stormwater Management Study (TSMS) Nodes

TSMS Node StreetLocation

TSMSWatershed Wash

Discharge (cfs)TSMS

RevisionDate

2-Year 10-year 100-Year DateVerified

DD-N0010 Grant Road @Oracle Road

Grant RoadWash

Grant RoadWash 286 604 1147 4/01

DG-N0020WarrenAvenue @Spring Street

Flowing WellsWash Unnamed 108 292 625 6/05

DG-N0030Grant Road @HighlandAvenue


DG-N0040Grant Road @MountainAvenue

Flowing WellsWash

MountainAvenue Wash 47 146 347 6/05

DG-N0110Water Street@ WilsonAvenue


DG-N0120 Grant Road @Treat Avenue


GL-N0070Country Club@ SenecaStreet

ChristmasWash

ChristmasWash 305 681 1280 Draft

GG-N0016Grant Road @BelvedereAvenue

AlvernonWash Midway Wash 310 753 1275 6/01

GG-N0035Grant Road @ColumbusBoulevard

AlvernonWash

ColumbusWash 168 392 813 6/01


Exhibit 2-2 – Tucson Stormwater Management Study (TSMS) Concentration Points for Nodes(continued)

TSMS Node Location Watershed Wash

Discharge (cfs) RevisionDate

2-Year 10-year 100-Year DateVerified

GG-N0055 Grant Road @Alvernon Way

AlvernonWash

AlvernonWash 383 957 1923 6/01

GD-N0010 Grant Road @Swan Road

Swan RoadWash

Swan RoadWash 103 233 522 Draft

2.2 Precipitation

100-year, one-hour precipitation values for the offsite hydrologic analysis were determined from theStandard Manual for Drainage Design and Floodplain Management in Tucson, Arizona (December1989, Revised July 1998, referred to as the Drainage Design Manual from here on). Table 4.1 of theDrainage Design Manual was used to determine the areally reduced one-hour rainfall depths. Thewatersheds that were analyzed for the purposes of design were less than 1 square mile in area orbetween 1 and 2 square miles in area. The result was a 100-year, one-hour areally reduced rainfalldepth of 3.0 and 2.9 inches, respectively. Appendix B contains excerpts from the Drainage DesignManual that were used for this study.

2.3 Soil Types

The type of soil and soil conditions are the major factors affecting infiltration and resultant storm waterrunoff. The Natural Resources Conservation Service (NRCS) has classified soils into four HydrologicSoil Groups (HSG), relating infiltration with runoff coefficients which are used for calculation of runoffrates. The HSG categories are based on properties that influence runoff, such as water infiltration rate,soil texture, natural discharge and antecedent moisture condition. The runoff potential is based on theamount of runoff at the end of a long duration storm that occurs after wetting and swelling of the soilthat is not protected by vegetation.

Soil groups were determined using the City of Tucson Transportation Department GIS database. Theproject watersheds consist of soil types B and D. Exhibit A-2, located in Appendix A, provides a mapshowing soil group locations. According to Chapter 7 of the National Engineering Handbook (NRCS,2009), Type B soils have a moderately low runoff potential due to moderate infiltration rates. Thesesoils consist primarily of moderately deep to deep and moderately well to well drained soils withmoderately fine to moderately coarse textures. Water movement through these soils is moderately rapid.The depth to any restrictive layer is greater than 20 inches and to a permanent water table is deeper thantwo feet. Group D soils have a high runoff potential due to very slow infiltration rates. These soilsconsist primarily of clays with high swelling potential, soils with permanently high water tables, soilswith a clay pan or clay layer at or near the surface, and shallow soils over nearly impervious parentmaterial. Water movement through the soil is slow or very slow. A restrictive layer of nearlyimpervious material may be within 20 inches of the soil surface and the depth to a permanent watertable is shallower than two feet.


2.4 Land Use

The land use types found in the contributing watersheds consist of urbanized areas with mixed landuses. The watersheds are predominantly composed of residential neighborhoods with few parks, andseveral areas scattered with commercial, retail and school developments. Included in the watersheds isthe northern portion of the University of Arizona, near and around the medical campus. For purposes ofhydrologic calculations, a land use of Highly Urban areas was used. Exhibit A-3, located in AppendixA, provides an aerial map of the upstream watersheds.

2.5 FEMA Mapping

Portions of the Grant Road study area are located within a FEMA designated 100-year floodplain. Allthe floodplains cross Grant Road at a nearly perpendicular or oblique angle. These crossings includeWilson Avenue Wash, Alvernon Wash, Midway Wash and Columbus Wash. Exhibit 2-3 provides asummary of the FEMA Floodplains along Grant Road. Exhibit A-4, located in Appendix A, providesexhibits of the existing FEMA floodplains.

Exhibit 2-3 – FEMA Floodplains Affecting Grant Road

FEMA Panel Map Number RevisionDate Location FEMA

Floodplain Zone

1639K, 1643K,

2227K

04019C1639K,

04019C1643K,04019C2227K

8-Sep-99 WilsonAvenue Wilson Wash

Zone AH: 100-year flooddepths of 1-3 feet (usuallyareas of ponding); base floodelevations determined.

1643K, 2231K 04019C1643K,04019C2231K 8-Sep-99 Alvernon

WayAlvernon Wash(street wash)

Zone AH: 100-year flooddepths of 1-3 feet (usuallyareas of ponding); base floodelevations determined.

1644K, 2232K 04019C1644K,04019C2232K 8-Sep-99 Columbus

BlvdColumbusWash

Zone AE: 100-year base floodelevations determined.

Any modifications or revisions to the Grant Road roadway profile may be considered an impact toestablished floodplains. FEMA regulations state that encroachments may not increase the base flood(100-year) water surface elevations of regulatory floodplains no more than one foot. However the Cityof Tucson floodplain ordinance states that encroachments may not increase the base flood water surfaceelevations of regulatory floodplains by no more than 0.1 feet . Encroachment and impacts of the GrantRoad improvements into the floodplain will need to be considered during final design. The proposedimprovements should be designed such that the base flood water surface elevation does not increasewhich is also known as a “no-rise” condition.

2.6 Hydrologic Methodology

The Grant Road Improvement Plan project encompasses several TSMS concentration points; however,significant portions of the proposed project will require the determination of additional peak flow ratesfor the design of the projects’ drainage improvements and/or documentation of existing system


deficiencies. This project falls completely within the jurisdiction of the City of Tucson and allhydrologic calculations will be prepared utilizing The Flood Peak Estimator Procedure as provided inChapter 4 of the Drainage Design Manual.

2.7 Existing Hydrologic Data (TSMS Node data) Review

The Tucson Stormwater Management Study (TSMS) was prepared in December of 1995 and wasapproved by the City of Tucson in February 1996. All TSMS hydrologic modeling prepared forwatersheds of less than ten square miles was approved by the Federal Emergency Management Agency(FEMA) on May 12, 1996. The City of Tucson prefers that confirmed/verified TSMS peak dischargesbe used in lieu of the Flood Peak Estimator Procedure (described in the Drainage Design Manual) if theappropriate data for the project is available. In cases where effective FEMA flows differ from theTSMS peak discharges, the effective FEMA flows are to be used for design.

The project encompasses 11 TSMS nodal points that can be used for the basis of design. The TSMSnodes that will be used as design data are summarized in Exhibit 2-5. Exhibit A-1, located inAppendix A, shows the location of the TSMS nodes.

2.8 Hydrologic Analysis and TSMS Comparison

Although significant TSMS node data is available near and around the project site, additionalhydrologic computations were prepared to verify and complement the existing TSMS data. The goal ofthe additional hydrologic analysis is to supplement the TSMS results to provide a complete set of designflow rates to use for the Grant Road Improvement Plan project drainage improvement recommendationsand existing systems documentations. As presented in the previous section, 11 TSMS nodes providedesign flow data that should be used for this project, with three nodes requiring slight modifications to(area based “cfs/acre”) flow rates due to the location of the TSMS node. In addition to the TSMS data,eight additional confluence points have been identified as requiring design flow rates. Kimley-Horncompleted an analysis of the project’s tributary watersheds to fully comprehend and compare (withrespect to TSMS) results.

The Grant Road Improvement Plan’s tributary watersheds were delineated using two foot contourinterval topographic mapping (1998 PAG Topography, NAVD88) and were field verified. Watershedswere delineated at concentration points based on the need for design discharges at the intersection ofGrant Road. The basins that were delineated followed closely with the City of Tucson major watersheddelineations, with some minor differences. These minor differences are due to the redevelopment ofparcels and the construction or reconstruction of roadways. These minor differences were neglected incalculations due to the minor effect on discharges. Exhibit A-5, located in Appendix A, shows thedelineated watersheds and the concentration points for each watershed, including the City of Tucsonmajor watershed delineations. Exhibit 2-4 is a summary of all tributary area watersheds and therespectful discharges for each watershed. Appendix B contains the Hydrologic Data Sheets for eachconcentration point.

A comparison between KHA calculated discharges, TSMS discharges, and FEMA regulatory dischargesis shown in Exhibit 2-5.


Exhibit 2-4 – Summary of Hydrologic Analysis

KHA SUBBASIN ID AREA Q2 Q5 Q10 Q25 Q50 Q100 CFS/Acre

NUMBER (ACRES) (CFS) (CFS) (CFS) (CFS) (CFS) (CFS) (CFS)

1 202.7 197 329 493 713 932 1096 5.4

2 4.4 8 13 19 27 34 38 8.6

3 20.9 33 53 75 105 136 151 7.2

4 37.6 59 94 135 189 243 270 7.2

5 106.4 127 203 290 406 521 579 5.4

6 115.1 96 153 218 305 392 436 3.8

7 176.4 139 220 315 441 567 630 3.6

8 36.6 61 98 139 195 251 279 7.6

9 206.4 170 270 385 539 693 771 3.7

10 190.1 149 237 338 474 609 677 3.6

11 100.8 93 148 211 295 380 422 4.2

12 790.5 248 395 564 790 1015 1128 1.4

13 54.9 51 81 116 162 209 232 4.2

13A 45.8 50 79 113 158 203 225 4.9

14 157.9 127 202 289 405 520 578 3.7

15 64.8 111 177 253 354 455 505 7.8

16 634.5 314 500 714 1000 1286 1429 2.3

17 939.3 379 603 862 1207 1551 1724 1.8

18 60.1 53 84 120 168 215 239 4.0

19 221.7 171 272 389 544 699 777 3.5

098134000 Grant Road Improvement Plan2010 07 23 PRELIM DRAINAGE REPORT 13 Preliminary Drainage ReportOctober 2010

Exhibit 2-5 – 100-Year Hydrologic Analysis Comparison Summary

SUB BASIN ID Basin Area (sq. mi.) Basin Area (acres)100 Year Flow

Rate (cfs)FEMA

Flow Rate

KHA TSMS Location KHATSMS-Total

TSMS -Reduction KHA

TSMS- Total

TSMS -Reduction KHA TSMS

(cfs)

1 DD-N0010 Grant Road @Oracle Road 0.32 0.303 0.297 202.71 193.92 190.08 1096 1147 -

2 N/A N/A 0.01 - - 4.35 - - 38 - -

3 N/A N/A 0.03 - - 20.93 - - 151 - -

4 N/A N/A 0.06 - - 37.58 - - 270 - -

5 DG-N0040 Grant Road @Mountain Avenue 0.17 0.13 0.105 106.44 83.20 67.20 505 347 -

6 DG-N0030 Grant Road @Highland Avenue 0.18 0.203 0.164 115.14 129.92 104.96 436 592 -

7 DG-N0020 Warren Avenue @Spring Street 0.28 0.2975 0.096 176.38 190.40 61.44 630 625 -

8 N/A N/A 0.06 - - 36.58 - - 279 - -

9 DG-N0110 Water Street @Wilson Avenue 0.32 0.635 0.289 206.40 406.40 184.96 771 1019

10 N/A N/A 0.30 - - 190.13 - - 677 - -

11 DG-N0120 Grant Road @Treat Avenue 0.16 0.158 0.13 100.78 101.12 83.20 422 419 -

12 GL-N0070 Country Club @Seneca Street 1.24 *** *** 790.51 - - 1128 *** -

13 N/A N/A 0.09 - - 54.88 - - 232 - -

14 N/A N/A 0.25 - - 157.93 - - 578 - -

15 N/A N/A 0.10 - - 64.78 - - 505 - -

098134000 Grant Road Improvement Plan2010 07 23 PRELIM DRAINAGE REPORT 14 Preliminary Drainage ReportOctober 2010

Exhibit 2-5 – 100-Year Hydrologic Analysis Comparison Summary (continued)

SUB BASIN ID Basin Area (sq. mi.) Basin Area (acres)100 Year Flow

Rate (cfs)FEMA

Flow Rate

KHA TSMS Location KHATSMS-Total

TSMS -Reduction KHA

TSMS- Total

TSMS -Reduction KHA TSMS

(cfs)

16 GG-N0055 Grant Road @Alvernon Way 0.99 0.995 0.387 634.51 636.80 247.68 1429 1922 2260

17 GG-N0035Grant Road @

ColumbusBoulevard

1.47 0.42 0.146 939.30 268.80 93.44 1724 813 1838

18 GG-N0016 Grant Road @Belvedere Avenue 0.09 1.094 0.114 60.09 700.16 72.96 239 1275 -

19 GD-N0010 Grant Road @Swan Road 0.35 0.312 0.227 221.72 199.68 145.28 777 522 -


2.9 Offsite Hydrologic Recommendations

Sections 2 of this report serve as documentation of the design flow rates tributary to the Grant RoadImprovement Project that will be used to size the recommended improvements. The order ofprecedence for establishing offsite flows is: effective FEMA flows, verified/confirmed TSMS results,and then KHA calculated discharges. Flow rates to be used and the source of each are presented inExhibit 2-6. The flow rates identified in Exhibit 2-6 serve as the design flow rates to be used foroffsite drainage facility improvement recommendations.

Exhibit 2-6 – Summary of Recommended Offsite Discharges

SubbasinID

TSMS

Node ID Q2 (cfs) Q10 (cfs) Q100 (cfs) Data From1 DD-N0010 286 604 1147 TSMS

2 N/A 8 19 38 KHA

3 N/A 33 75 151 KHA

4 N/A 59 135 270 KHA

5 DG-N0040 47 146 347 TSMS

6 DG-N0030 122 287 592 TSMS

7 DG-N0020 108 292 625 TSMS

8 N/A 61 139 279 KHA

9 DG-N0110 166 455 1019 TSMS

10 N/A 149 338 677 KHA

11 DG-N0120 70 190 420 TSMS

12 GL-N0070 248 564 1128 KHA

13 N/A 51 116 232 KHA

13A N/A 50 113 225 KHA

14 N/A 127 289 578 KHA

15 N/A 111 253 505 KHA

16 GG-N0055 370 1010 2260 FEMA

17 GG-N0035 300 820 1838 FEMA

18 GG-N0016 310 753 1275 TSMS

19 GD-N0010 171 389 777 KHA


3. ONSITE ROADWAY HYDROLOGYThe purpose of Sections 3 and 5 is to present the onsite preliminary drainage analysis that wascompleted in conjunction with 30% GRIP design plans, profile, and layouts. The analysis identifiessegments of Grant Road that will require new or additional drainage facilities and modifications toexisting facilities (i.e. storm drain trunk lines in Grant Road and the required reconstruction of existinginlets). This analysis also identifies areas that will require new storm drains and inlets to satisfy thedesign criteria provided in the separate project document Drainage Design Criteria Memorandum(KHA, 2009).

The majority of the offsite watersheds have large time of concentrations (mostly greater than 25minutes, and range from 16-117 minutes). Local onsite roadway peak runoff will have a time ofconcentration of five (5) minutes and are designed to be collected and conveyed prior to the peak flowrates from the offsite watersheds. As such, calculations for onsite hydrology and hydraulics are limitedto the Grant Road projects limits.

A typical onsite drainage area was calculated to determine a ratio of flow rate per area (cfs/acre) thatcould be used to identify roadway segments within the project limits that exceed the conveyancecapacity of the street. The typical calculation uses the City of Tucson Hydrologic Methods as describedin Chapter 4 of the Drainage Design Manual. The typical section hydrology assumes a flow path of300 feet, flowing along an improved channel watershed, with soil types B and 90% impervious area,yielding a runoff coefficient of 0.96. The time of concentration is 5 minutes with a 100-year rainfallintensity of 9.6 inches per hour. An area of 1 acre produces 9.22 cfs for the 100 year storm event and4.1 cfs for a 10 year storm event, as summarized in Exhibit 3-1. A City of Tucson Hydrologic Methodwork sheet for the typical pavement drainage area is included in Appendix C.

Exhibit 3-1 – Summary of Typical Onsite Flow Rate Per Unit Area

10-Year Storm Event

(cfs/acre)

100-Year StormEvent

(cfs/acre)4.1 (5)* 9.2 (10)*

*Discharge per acre rounded up for design purposes.

Onsite sub-basins were delineated from contours of the proposed Grant Road improvements. Thesesub-basin delineations are provided in Exhibit A-6 of Appendix A. Onsite sub-basins were namedbased on the side of Grant Road (north/south) and offsite watershed that each onsite sub-basin waslocated within. For instance, the name S07D indicates:

S an onsite sub-basin on the south side (eastbound traffic) of Grant Road;

07 within offsite watershed 7;

D fourth sub-basin in that particular offsite watershed (labeled alphabetically west to east).

The typical onsite flow rates per area shown in Exhibit 3-1 were applied to each sub-basin to determine10-year and 100-year discharges. These flows are summarized in Exhibit 3-2 for the westbound trafficsub-basins and in Exhibit 3-3 for the eastbound traffic sub-basins. Proposed roadway improvementsinclude median separation of the westbound and eastbound traffic lanes.


Exhibit 3-2 – Summary of Westbound Onsite Sub-basin Discharges

Area Drains Drains to Area Q10 Q100

ID to Inlet Cross Street (ac) (cfs) (cfs)N01A 93+76 L Grant 1.16 5.8 11.6

N01B 101+45 L Oracle 1.11 5.6 11.1

N01C 106+17 L Oracle 2.22 11.1 22.2

N01D - Stone 2.09 10.5 20.9

N02A - Fontana 1.10 5.5 11.0

N03A - Geronimo 1.97 9.9 19.7

N04A 155+70 L Hampton 1.22 6.1 12.2

N04B 155+70 L Hampton 1.81 9.1 18.1

N05A 174+50 L59 Mountain 0.48 2.4 4.8

N05B 174+50 L49 Mountain 0.96 4.8 9.6

N05C - Mountain 1.29 6.5 12.9

N06A 183+37 L Highland 1.67 8.3 16.7

N07A - Warren 1.71 8.5 17.1

N08A - Norris 1.34 6.7 13.4

N08B - Norris 1.25 6.3 12.5

N09A 221+81 L Wilson 0.38 1.0 1.9

N09B 222+82 L Wilson 0.31 0.8 1.5

N09C 223+68 L Wilson 0.14 0.4 0.7

N09D - Wilson 0.44 1.1 2.2

N09E - Wilson 1.04 5.2 10.4

N10A 223+64 L Tucson 1.10 5.5 11.0

N11A - Treat 2.35 11.7 23.5

N12A - Country Club 1.02 5.1 10.2

N12B 259+37 L Country Club 1.68 8.4 16.8

N13A - Edith 0.90 4.5 9.0

N14A - Sparkman 1.47 7.3 14.7

N14B 285+19 L Palo Verde 1.44 7.2 14.4

N14C 290+98 L Palo Verde 1.03 14.9 29.7

N15A - Dodge 1.82 9.1 18.2

N16A - Alvernon 1.60 8.0 16.0

N16B - Sycamore 1.12 5.6 11.2

N16C - Walnut 2.19 14.2 28.3


Exhibit 3-2 – Summary of Westbound Onsite Sub-basin Discharges (continued)


ID to Inlet Cross Street (ac) (cfs) (cfs)N17A - Columbus 0.81 4.0 8.1

N17B - Goyette 0.65 3.2 6.5

N18A - Goyette 1.09 2.7 5.4

N18B 351+30 L Goyette 0.72 1.8 3.6

N18C 355+89 L Goyette 1.04 5.2 10.4

N19A 365+99 L Swan 1.35 6.7 13.5

N19B 370+31 L Swan 1.25 6.3 12.5

Exhibit 3-3 – Summary of Eastbound Onsite Sub-basin Discharges


ID to Inlet Cross Street (ac) (cfs) (cfs)S01A 94+00 R Grant 1.39 6.9 13.9

S01B 101+55 R Oracle 0.91 4.5 9.1

S01C 106+14 L Oracle 1.18 5.9 11.8

S01D 111+95 R Oracle 3.05 15.2 30.5

S02A - Fontana 0.98 4.9 9.8

S03A - Geronimo 2.07 10.3 20.7

S04A 155+70 L Hampton 1.22 6.1 12.2

S04B 155+70 L Hampton 2.25 11.3 22.5

S05A 176+59 R Mountain 1.52 7.6 15.2

S05B - Mountain 0.76 3.8 7.6

S06A 183+08 R Mountain 0.62 3.1 6.2

S06B 185+71 R Mountain 0.85 4.3 8.5

S06C 184+74 R Mountain 0.56 2.8 5.6

S07A 194+67 R Warren 0.45 2.2 4.5

S07B 195+36 R Warren 0.32 1.6 3.2

S07C - Warren 0.58 2.9 5.8

S07D 198+55 R Warren 0.75 3.8 7.5

S08A - Norris 1.35 6.7 13.5

S08B - Norris 1.42 7.1 14.2

S09A 221+74 R59 Wilson 0.38 0.9 1.9


Exhibit 3-3 – Summary of Eastbound Onsite Sub-basin Discharges (continued)


ID to Inlet Cross Street (ac) (cfs) (cfs)S09B 221+74 R49 Wilson 0.23 0.6 1.2

S09C 221+82 R Wilson 0.30 0.8 1.5

S09D 223+68 R Wilson 0.12 0.3 0.6

S09E - Wilson 0.63 1.6 3.2

S09F - Wilson 1.25 6.2 12.5

S10A 233+97 R Tucson 0.49 2.4 4.9

S10B 235+05 R Tucson 0.57 2.8 5.7

S11A - Treat 2.43 12.1 24.3

S12A - Country Club 1.14 5.7 11.4

S12B 259+71 R Country Club 1.46 7.3 14.6

S13A - Edith 0.85 4.2 8.5

S14A - ? 1.53 7.7 15.3

S14B - Palo Verde 1.23 6.1 12.3

S14C 291+05 R Palo Verde 1.04 5.2 10.4

S15A - Dodge 1.94 9.7 19.4

S16A - Alvernon 1.60 8.0 16.0

S16B - Sycamore 1.61 11.3 22.6

S16C - Sycamore 1.29 3.2 6.5

S17A - Columbus 0.74 3.7 7.4

S17B - Goyette 0.64 3.2 6.4

S18A - Goyette 2.96 14.8 29.6

S19A 365+64 R Swan 1.87 9.3 18.7

S19B 375+02 R Swan 0.66 3.3 6.6

The overall impact of the project with respect to offsite peak flow rates is assumed to be negligible fortwo reasons:

1.) The project will be widening the existing roadway in areas where the majority of the existing landuses impacted by the project consist of developed impervious land uses such as commercial andresidential properties. The roadway will include depressed landscaped areas within the median andwithin the edges of the roadway, resulting in negligible increases in impervious area.

2.) The offsite peak flow rates to storm drain facilities and street conveyance systems described inSection 2 are generated from offsite watersheds that have time of concentrations that are much longerthan the local roadway drainage peak flow rates described in Section 3. The increase in offsite peak flowrate from the proposed roadway improvements would be negligible.


4. OFFSITE HYDRAULICSThe majority of Grant Road within the project limits relies on local streets and washes with minimallysized storm drain systems to convey stormwater to ultimate discharge locations. The existing stormdrain facilities and street wash capacities were analyzed to determine if deficiencies in conveyancecapacity exist and to compare these capacities to the proposed conditions.

This project is a linear project that intersects large watershed basins several miles from the ultimatedischarge locations. A large regional infrastructure improvement would be required to improve GrantRoad and cross streets to meet the City of Tucson’s drainage design criteria. These improvements arenot included as part of the Grant Road Improvement Project scope. The project scope of work does notinclude analysis of potential alternatives to improve existing stormwater deficiencies for the crossdrainage systems.

The preliminary drainage analysis demonstrates that proposed improvements to stormwater conveyancewill preserve or improve the existing conditions stormwater conveyance. Since the majority of theoffsite runoff flows directly across Grant Road the roadway geometry was designed to maintain andpreserve existing drainage conditions and in several locations the conditions were improved.

4.1 Existing Offsite Storm Drain Hydraulics

The storm drain capacities of each cross drainage facility were calculated using a normal depthcalculation method. This calculation assumes that no pressure flow is allowed within the system anddownstream tail water will have no impacts on the capacities of the storm drains. The normal depthpipe section was calculated at each Grant Road crossing location with slope and pipe size informationgathered from as-built information. The normal depth calculations for each storm drain facility wereprepared in Bentley’s FlowMaster Computer Program (2005 Version 8.01). The calculations have beenincluded in Appendix D and the results are summarized in Exhibit 4-2.

The majority of storm drain facilities within the Grant Road Improvement Project limits are dedicated tothe offsite cross drainage. Many of the storm drain facilities convey flows from the upstreamwatersheds to the ultimate discharge points; the Santa Cruz River to the west or the Rillito River to thenorth. Many of these systems contain inlets and large street grates within the roadway. These systemsare shown in Exhibit A-6 within Appendix A.

Exhibit 4-2 – Summary of Existing Storm Drain Capacities

SubBasin

IDLocation Storm Drain

Size/Material Slope (%) Facility Capacity(cfs) 1

1 Oracle North 36" RCP 0.30 37

1 Oracle South 60" RCP 0.64 208

1 Grant East of Oracle 48" RCP 1.17 155

1 Grant West of Oracle 66" RCP 1.06 346

4 1st Ave Sump Outlet Pipe 30" RCP 0.77 36

5 Mountain Avenue Across Grant 53x34 Elliptical - 60x38Elliptical 0.749 - 0.663 200

6 Highland Ave Across Grant 36" RCP 0.34 39


Exhibit 4-2 – Summary of Existing Storm Drain Capacities (continued)

SubBasin

IDLocation Storm Drain

Size/Material Slope (%) Facility Capacity(cfs)1

6 Vine Ave Across Grant 36" RCP 0.84 61

7 Warren Ave Across Grant 72" RCP 0.35 251

9 Wilson Ave Across Grant 42" RCP 0.53 73

10 Tucson Blvd Across Grant 60" RCP 0.25 130

12 Country Club Rd Across Grant 60" RCP 0.67 213

13 Edith/Northway Across Grant 42" CMP 0.70 50

14 Palo Verde Blvd Across Grant 42" CMP 0.59 46

16 Alvernon Way Across Grant 96" RCP 0.82 826

17 Columbus Blvd Across Grant 48" RCP 1.72 188

Goyette Ave Across Grant (3) 108" CIPP 0.86 3474

18 Belvedere Ave North of Grant (2) 96" x 36" RCB 0.18 245

Madelyn to Belvedere along Grant 24" RCP 0.30 12

19 Swan North of Grant 54" RCP 0.48 136

East of Swan on Grant 42" RCP 0.30 55

1. Capacity is calculated within FlowMaster Computer Program using normal depth calculations assuming full flowdepth.

4.2 Offsite Street Hydraulics Methodology

Street hydraulics are a large part of the overall stormwater conveyance system considering theundersized storm drain systems and the large watershed areas that drain across the Grant Road Project.Within the Grant Road Improvement Project limits, street washes are the primary conveyance systemwith storm drain infrastructure in place at several locations. The goal of this drainage study and 30%preliminary design is to minimize impacts to the street washes that cross Grant Road. A comparison ofthe conveyance capacities of both existing and proposed conditions was prepared and is discussed infurther detail below.

Per the City of Tucson’s drainage design criteria, streets should be designed to safely convey the 10-year storm event within the curb while maintaining an 11-ft travel lane in both directions and to conveythe 100-year storm event within the right-of-way with a maximum depth of 1 foot. The capacity of eachstreet section was determined following these design criteria limitations.

The conveyance capacities of streets were calculated using a normal depth calculation within Bentley’sFlowMaster Computer Program. A cross-section of each street wash was taken at the downstream(typically, north of Grant Road), upstream (typically, south of Grant Road) and at the centerline ofGrant Road. These cross-sections were entered into an irregular channel section calculation worksheetwith the appropriate slopes (longitudinal street slope for upstream and downstream calculations androadway cross slope for center line of Grant Road) and Manning’s coefficient of 0.016. To calculate the


capacity of the street section (after physical characteristics are defined), the discharge (flow rate, cfs)can be solved for once the depths of flow are adjusted to meet the design criteria as described above.

4.3 Existing Offsite Street Hydraulics

The existing street capacities were calculated using the criteria and methods described above. Exhibit4-3 provides a summary of the existing street capacities as defined by the City of Tucson’s drainagedesign criteria for both the 10-year and 100-year storm events. Existing street hydraulic calculationshave been prepared in Bentley’s FlowMaster computer program and are provided in Appendix E.

Exhibit 4-3 – Summary of Existing Street Capacities

SubBasin

IDLocation Facility Description Facility Capacity

(cfs)

1

Oracle, North of Grant10 Year Street 58

100 Year Street 95

Oracle, South of Grant10 Year Street 52

100 Year Street 199

Grant, East of Oracle10 Year Street 32

100 Year Street 155

Grant, West of Oracle10 Year Street 80

100 Year Street 131

2

6th/Fontana Avenue, Across Grant Rd 100 Year Street 821

Fontana Avenue, North of Grant Rd10 Year Street 43

100 Year Street 97

3

Geronimo to Fontana, On Grant Rd10 Year Street 28

100 Year Street 28

Geronimo, North of Grant Rd10 Year Street 87

100 Year Street 113

5Mountain Avenue, North of Grant Rd

10 Year Street 143

100 Year Street 224

Mountain Avenue, Across Grant Rd 100 Year Street 552

6Highland Ave, North of Grant Rd

10 Year Street 37

100 Year Street 248

Highland Ave, Across Grant Rd 100 Year Street 1332

7Warren Ave, North of Grant Rd

10 Year Street 62

100 Year Street 187

Warren Ave, Across Grant Rd 100 Year Street 251


Exhibit 4-3 – Summary of Existing Street Capacities (continued)

SubBasin

IDLocation Facility Description Facility Capacity

(cfs)

8Norris Ave, North of Grant Rd

10 Year Street 46

100 Year Street 103

Norris Ave, Across Grant Rd 100 Year Street 989

9Wilson Ave Northern Drainage Way

Channel 100 Year Street 766

Wilson Ave, Across Grant Rd 100 Year Street 699

10 Tucson Blvd to Wilson Drainage Way, onGrant

10 Year Street 12

100 Year Street 95

11Treat Ave, North of Grant Rd

10 Year Street 62

100 Year Street 125

Treat Ave, Across Grant Rd 100 Year Street 715

12Country Club Rd, North of Grant Rd

10 Year Street 175

100 Year Street 175

Country Club Rd ,Across Grant Rd 100 Year Street 499

14

Sparkman Blvd, North of Grant Rd10 Year Street 13

100 Year Street 83

Sparkman, Across Grant Rd 100 Year Street 1771

Palo Verde Blvd, North of Grant Rd10 Year Street 110

100 Year Street 110

Palo Verde Blvd ,Across Grant Rd 100 Year Street 191

16

Alvernon Way, North of Grant Rd 10 Year Street 104

100 Year Street 436

Alvernon Way ,Across Grant Rd 100 Year Street 613

17

Columbus Blvd, North of Grant Rd - noStormdrain to north but reduces flow

downstream in street

10 Year Street 133

100 Year Street 228

Columbus Blvd, Across Grant Rd 100 Year Street 235

Goyette Ave, North of Grant Rd10 Year Street 98

100 Year Street 208

Goyette Ave, Across Grant Rd 100 Year Street 1597

18Madelyn to Belvedere, along Grant Rd

10 Year Street 232

100 Year Street 655


Exhibit 4-3 – Summary of Existing Street Capacities (continued)

SubBasin ID Location Facility Description

Facility Capacity

(cfs)Swan Rd, Across Grant Rd 100 Year Street 5

19

Swan Rd, North of Grant Rd10 Year Street 23

100 Year Street 286

Swan Rd, South of Grant Rd10 Year Street 11

100 Year Street 134

East of Swan, on Grant Rd

10 Year Street 42

100 Year Street 42

4.4 Proposed Offsite Street Hydraulics

Street capacities were calculated using the criteria and methods as described above. Exhibit 4-4provides a summary of the calculated street capacities compared with the existing street capacities asdefined by the City of Tucson’s drainage design criteria for both the 10-year and 100-year storm events.The north and south street capacities have been omitted from Exhibit 4-4 because the capacities haveremained unchanged or slightly increased due to minimal geometric changes to these streets. Proposedstreet hydraulic calculations were prepared in Bentley’s FlowMaster computer program and areprovided in Appendix E.

The Grant Road Improvement Project will include raised medians along the entire corridor. In areasthat contain large cross drainage flows, medians will consist of curb cuts and erosion measures to allowflow to travel across the roadway without impeding the flow or ponding on the upstream side of themedian.

Exhibit 4-4 – Summary of Proposed vs Existing Street Capacities

SubBasin

IDLocation Storm

Event

ExistingConditionsPeak Flow

(cfs)

ExistingConditions

StreetCapacity

(cfs)

ProposedConditions

StreetCapacity

(cfs)

Change inStreet

Capacity(cfs)

1Grant East of Oracle

10 Year 604 32 31 -1100 Year 1147 155 180 25

Grant West of Oracle10 Year 604 80 75 -5100 Year 1147 131 527 397

2 6th/Fontana AvenueAcross Grant 100 Year 38 821 1627 806

5 Mountain AvenueAcross Grant 100 Year 347 552 915 363


Exhibit 4-4 – Summary of Proposed vs Existing Street Capacities (continued)

SubBasin

IDLocation Storm

Event

ExistingConditionsPeak Flow

(cfs)

ExistingConditions

StreetCapacity

(cfs)

ProposedConditions

StreetCapacity

(cfs)

Change inStreet

Capacity(cfs)

6 Highland Ave AcrossGrant 100 Year 592 1332 1545 213

7 Warren Ave AcrossGrant 100 Year 625 251 486 235

8 Norris Ave AcrossGrant 100 Year 279 989 1617 628

9 Wilson Ave NorthernDrainage Way 100 Year

1019766 1048 282

9 Wilson Ave AcrossGrant 100 Year 699 1659 960

10Tucson Blvd toWilson DrainageWay on Grant

10 Year 338 12 23 10

100 Year 677 95 161 66

11 Treat Ave AcrossGrant 100 Year 420 715 1862 1147

12 Country Club RdAcross Grant 100 Year 1280 499 1380 881

13 Edith/NorthwayAcross Grant 100 Year

2320 2371 2371

14 Sparkman AcrossGrant 100 Year 1771 3204 1433

14 Palo Verde BlvdAcross Grant 100 Year 578 191 374 182

16 Alvernon WayAcross Grant 100 Year 2260 613 1180 566

17

Columbus BlvdAcross Grant 100 Year

1838235 251 16

Goyette Ave AcrossGrant 100 Year 1597 2194 598

19

Swan Rd AcrossGrant 100 Year 522 5 678 674

Swan North of Grant10 Year 233 23 45 22100 Year 522 380 114 -130

Swan South of Grant10 Year 233 11 17 6100 Year 522 160 129 -5

As demonstrated in Exhibit 4-4, the Grant Road Improvements will result in an increase in the majorityof the street capacities. Exceptions are east and west of Oracle on Grant Road (10-year capacity).GrantRoad east and west of Oracle Road has reduced capacities for the 10-year storm event by only 1 and 5


cfs, respectively. The proposed roadway cross section east of Oracle Road was changed from a normalcrown section to a full superelevated cross section, significantly reducing the capacity of the curb heightflow depth. The decrease of capacity for the 10-year storm event for these two areas is considered to benegligible. The 100-year storm event capacity has increased and will provide additional conveyance forthese larger storm events.

The capacity of 6th Ave/Fontana Ave crossing Grant Road has been reduced significantly; however thewatershed basin flow draining to this location is less than the capacity of this crossing. The 100-yearstorm event peak flow rate reaching Grant Road at this intersection is 38 cfs. The proposed roadwaycapacity is 284 cfs, providing adequate conveyance for the tributary areas 100-year peak runoff.

North and south of Grant on Swan also show to have a decrease in street capacities. This intersectionhas significant amount of flow that does not make it all the way from the south of grant to the north ofgrant due to the crossing of grant road where the majority of the flow in existing conditions is able toflow west along grant instead of flowing across the intersection and onto Swan on the northern side ofGrant Road. The intersection of Swan will require additional studies when finalizing the design tomaintain consistent drainage with existing conditions.

4.5 Combined Offsite Capacity (Storm Drain and Street)

The total drainage facilities capacity was calculated using the proposed street capacities and thestorm drain facilities that contribute to the drainage basin’s conveyance across Grant Road.Exhibit 4-5 summarizes the total drainage capacity for both existing and proposed conditionsalong with the peak flow rate reaching those facilities. Exhibit 4-5 – Summary of Combined

Proposed vs Existing Capacities

SubbasinID Location Facility

Description

ExistingConditions

FacilityCapacity

(cfs)

ProposedConditions

FacilityCapacity

(cfs)

Q10(cfs)

Q100(cfs)

1

Grant East ofOracle

Pipe 155 155

604 1147

10 Year Street 32 31


10 Year Capacity 187 186100 Year Capacity 310 335

Grant West ofOracle

Pipe 346 346




26th/Fontana

Avenue AcrossGrant

100 Year StreetCapacity 821 1627 19 38

4 1st Ave SumpInlet Pipe 36 36 135 270


Exhibit 4-5 – Summary of Combined Proposed vs Existing Capacities (continued)


Description

ExistingConditions

FacilityCapacity

(cfs)

ProposedConditions

FacilityCapacity

(cfs)

Q10(cfs)

Q100(cfs)

5 Mountain AvenueAcross Grant

Pipe 200 200

146 347100 Year Street 552 915

100 Year Capacity 752 1115

6Highland AveAcross Grant

Pipe 39 39

287 592100 Year Street 1332 1545


Vine Ave Pipe 61 61

7 Warren AveAcross Grant

Pipe 251 251

292 625100 Year Street 251 486


8 Norris AveAcross Grant


9

Wilson AveNorthern

Drainage Way

100 Year ChannelCapacity 766 1048

455 1019Wilson Ave

Across Grant

Pipe 73 73



10

Tucson BlvdAcross Grant Pipe Capacity 130 130

338 677Tucson Blvd toWilson Drainage

Way on Grant

10 Year StreetCapacity 12 23

100 Year StreetCapacity 95 161

11 Treat Ave AcrossGrant


12 Country Club RdAcross Grant

Pipe 213 213

681 1280100 Year Street 499 1380


13

Edith/NorthwayAcross Grant

Pipe 50 50

116 232100 Year Street 0 2371

100 Year Capacity 50 2421Sparkman

Across Grant100 Year Street

Capacity 1771 3204


Exhibit 4-5 – Summary of Combined Proposed vs Existing Capacities (continued)


Description

ExistingConditions

FacilityCapacity

(cfs)

ProposedConditions

FacilityCapacity

(cfs)

Q10(cfs)

Q100(cfs)

14 Palo Verde BlvdAcross Grant

Pipe 46 46

289 578100 Year Street 191 374


16 Alvernon WayAcross Grant

Pipe 826 826

1010 2260100 Year Street 613 1180


17

Columbus BlvdAcross Grant

Pipe 188 188

820 1838



Goyette AveAcross Grant

Pipe 3474 3474



19

Swan Rd AcrossGrant

Pipe 136 136

233 522



Swan North ofGrant

Pipe 136 136




Swan South ofGrant

Pipe 75 75






4.6 Offsite Inlet Hydraulics and Median Curb Cuts

The Grant Road Improvement Project impacts a number of offsite inlets located on cross streetsintersecting Grant Road. As stated in previous sections, the intent of this drainage study and 30%preliminary design is to minimize impacts of the project on existing offsite drainage patterns.Therefore, offsite inlets were sized based on a comparative capacity analysis. A flow of 10 cfs wasassumed at curb inlets and slotted drain inlets, and a flow of 500 cfs was assumed at grate inlets thatextend the full width of inverted crown cross streets. These assumed flows were selected todemonstrate comparative efficiencies of the existing versus proposed inlets; these flows do not representany particular storm frequency or design event. The existing capacity of each impacted offsite inlet wascalculated with FlowMaster computer software. Per City of Tucson drainage standards (StandardsManual for Drainage Design and Management, 1989), factors of safety of 1.25 for curb inlets and 2.0for grate inlets and slotted drain inlets were used to reduce the effective opening length used in theFlowMaster calculations. A Manning’s roughness coefficient of 0.016 was used. An inlet depression of1 inch was assumed at inlets located at the outside curb of roadways, and no inlet depression wasassumed for all other locations. A summary of the existing inlet hydraulic results and full FlowMasteroutput reports at each location are presented in Appendix G.

Proposed inlet capacities were calculated following the same procedure as the existing inlet capacities,except that proposed roadway grades were used to calculates the longitudinal and cross slopes at eachinlet location. Proposed inlets were sized to meet or exceed the existing inlet capacity while followingstandard opening sizes. Proposed curb inlet sizes were limited to the standard opening lengths describedin the Pima County Standard Detail No. 308 (Catch Basin Type 3). There were a wide variety ofexisting grate inlet types and sizes within the project limits, so a single standard design did not work forevery inlet location. In order of precedence, proposed grate inlet sizes were based on Pima CountyStandard Detail No. 309 (Catch Basin Type 4), Neenah R-4999 Type L Series trench grate specification,or to match existing grate dimensions. A summary of the proposed inlet hydraulic results and fullFlowMaster output reports at each location are presented in Appendix H.

Proposed inlet capacities meet or exceed existing inlet capacities at all locations except Alvernon Way.Alvernon Way has an inverted crown cross section that will be maintained under proposed conditions.North of Grant Road, the existing inlets along Alvernon Way consist of four slotted drain inlets with atotal opening length of approximately 240 feet. The proposed improvements north of Grant Roadinclude two medians that effectively partition the street flow into three flow areas. These mediansprevent the effective use of a single slotted drain inlet so curb inlets are specified in the proposedimprovements. The proposed curb inlets are located at the approximate locations of the existing slotteddrains at reasonable intervals (spacing between 60 and 130 feet) but do not have the same capacity asthe existing slotted drain inlets. Multiple curb opening cells could be specified to equal the existinginlets capacity, but initial calculations showed that between two and five cells would be required at eachproposed curb inlet location. This many large curb openings within a relatively short distance is not avery practical drainage solution, so the 30% preliminary design shows only one cell at each proposedcurb inlet location. A more detailed study of hydrology and inlet hydraulics along Alvernon Wayshould be included in later design phases to determine the best solution for this offsite drainage area.

Median curb cuts are required at several locations to allow water to flow through the intersection withminimal restrictions. It was critical to allow for low flows to pass through the medians to alleviateponding and to pass minimally the 10 year storm event within the curb cuts proposed on the roadwayplans. To minimize traffic confusion these curb cuts were limited in size and will be delineated byevenly spaced dagmars to prevent cars from turning into the median breaks. Flowmaster was used to


approximate the capacity of these curb cut openings. These results are summarized in Exhibit 4-6below and Flowmaster calculations that were prepared are presented in Appendix I.


Exhibit 4-6 – Summary of Median Curb Cut Hydraulic Analysis

Curb Cut Location (see roadway plans) Curb Cut Capacity (cfs) Median Curb Cut Width (ft)4th Ave 149 401st Ave 162 40

Highland Ave 136 60Warren Ave 98 60Norris Ave 87 40Wilson Ave 161 76

Edith/Northway 511 147Sparkman 364 85

Ralph/Goyette Ave 331 72

5. ONSITE HYDRAULICS

5.1 Onsite Proposed Street Capacity

The primary objective of Grant Road drainage improvements is to safely convey the 10-year stormevent within the curb while maintaining an 11-foot travel lane in both directions and to convey the 100-year storm event within the right-of-way with a maximum depth of 1-foot. Calculations were preparedfor the capacities of the typical roadway cross sections. Three typical cross sections were analyzed todetermine the capacities of the proposed roadway; normal crown, a full super elevated section, and adouble crowned section. Exhibit 5-1 below provides a summary of proposed roadway cross-section’scapacities. These typical proposed capacities were calculated using Bentley’s FlowMaster computerprogram and have been provided in Appendix J.

Exhibit 5-1 – Summary of Proposed Onsite Street Capacities

Cross sectionCapacity

10 Year Capacity (cfs) 100 Year Capacity (cfs)

Normal Crown 10 100

Double Crown 18 160

Super Elevated 10 116

Detailed pavement drainage calculations were also performed for the onsite sub-basins described inSection 3 of this report. The spread and water depth were calculated for the 10-year storm event, andthe water depth was calculated for the 100-year storm event. These results, along with the type ofroadway cross section and number of calculated dry travel lanes during the 10-year storm event, aresummarized in Exhibit 5-2 for the westbound traffic sub-basins and in Exhibit 5-3 for the eastboundtraffic sub-basins. Note that the cross section type in these tables refers only to the typical half roadwaysection for drainage purposes; for instance a normal crown roadway would be shown as a super-elevatedsection for the westbound sub-basin and another super-elevated section for the eastbound sub-basin onthe opposite side of the center median. Full input parameters and FlowMaster results for the proposedstreet hydraulics are included as Appendix J.


Exhibit 5-2 – Summary of Westbound Onsite Pavement Hydraulics

Area Cross Section 10-Yr Spread 10-Yr Water 10-Yr Dry100-YrWater

ID Type (ft) Depth (ft) Lanes Depth (ft)N01A Super 14 0.27 2.4 0.35

N01B Super 16 0.31 2.2 0.40

N01C Super 18 0.37 2.0 0.48

N01D Super 19 0.37 1.9 0.48

N02A Super 13 0.26 2.5 0.34

N03A Super 21 0.42 1.7 0.55

N04A Super 14 0.27 2.4 0.35

N04B Super 21 0.41 1.8 0.54

N05A Super 10 0.20 2.7 0.26

N05B Super 13 0.26 2.5 0.34

N05C Super 15 0.29 2.3 0.38

N06A Super 18 0.36 2.0 0.46

N07A Super 14 0.28 2.3 0.37

N08A Super 15 0.30 2.3 0.38

N08B Super 12 0.24 2.5 0.32

N09A Crown 6 0.12 2.5 0.16

N09B Crown 6 0.11 2.6 0.14

N09C Crown 4 0.09 2.8 0.11

N09D Crown 6 0.13 2.5 0.17

N09E Super 16 0.33 2.2 0.42

N10A Super 12 0.24 2.5 0.32

N11A Super 22 0.45 1.6 0.58

N12A Super 16 0.33 2.1 0.43

N12B Super 20 0.40 1.8 0.51

N13A Super 16 0.31 2.2 0.40

N14A Super 19 0.37 1.9 0.49

N14B Super 18 0.36 2.0 0.47

N14C Super 23 0.45 1.6 0.59

N15A Super 21 0.41 1.8 0.54

N16A Super 19 0.38 1.9 0.50

N16B Super 17 0.34 2.1 0.45

N16C Super 24 0.49 1.4 0.63


Exhibit 5-2 – Summary of Westbound Onsite Pavement Hydraulics (continued)


ID Type (ft) Depth (ft) Lanes Depth (ft)N17A Super 15 0.30 2.3 0.40

N17B Super 14 0.28 2.4 0.36

N18A Crown 13 0.26 1.3 0.34

N18B Crown 11 0.23 1.6 0.29

N18C Super 17 0.34 2.1 0.43

N19A Super 18 0.35 2.0 0.46

N19B Super 18 0.36 2.0 0.47

Exhibit 5-3 – Summary of Eastbound Onsite Pavement Hydraulics


ID Type (ft) Depth (ft) Lanes Depth (ft)S01A Super 16 0.31 2.2 0.40

S01B Super 13 0.27 2.4 0.35

S01C Super 14 0.29 2.3 0.38

S01D Super 20 0.41 1.8 0.53

S02A Super 14 0.27 2.4 0.36

S03A Super 22 0.43 1.7 0.56

S04A Super 14 0.28 2.4 0.36

S04B Super 22 0.45 1.6 0.58

S05A Super 16 0.31 2.2 0.40

S05B Super 12 0.24 2.5 0.31

S06A Super 13 0.27 2.4 0.34

S06B Super 15 0.30 2.3 0.39

S06C Super 13 0.26 2.5 0.33

S07A Super 9 0.17 2.8 0.23

S07B Super 8 0.15 2.9 0.20

S07C Super 10 0.19 2.8 0.25

S07D Super 11 0.21 2.7 0.27

S08A Super 15 0.30 2.3 0.39

S08B Super 13 0.26 2.5 0.33


Exhibit 5-3 – Summary of Eastbound Onsite Pavement Hydraulics (continued)


ID Type (ft) Depth (ft) Lanes Depth (ft)S09A Crown 6 0.12 2.6 0.16

S09B Crown 5 0.10 2.7 0.13

S09C Crown 6 0.11 2.6 0.14

S09D Crown 4 0.08 2.9 0.10

S09E Crown 7 0.14 2.3 0.19

S09F Super 18 0.36 2.0 0.47

S10A Super 13 0.25 2.5 0.33

S10B Super 13 0.27 2.4 0.35

S11A Super 23 0.45 1.6 0.59

S12A Super 16 0.32 2.2 0.41

S12B Super 17 0.35 2.1 0.45

S13A Super 14 0.29 2.3 0.38

S14A Super 19 0.39 1.9 0.50

S14B Super 17 0.34 2.1 0.45

S14C Super 17 0.34 2.1 0.43

S15A Super 21 0.42 1.7 0.55

S16A Super 20 0.39 1.8 0.51

S16B Super 22 0.44 1.7 0.57

S16C Crown 14 0.27 1.2 0.35

S17A Super 13 0.27 2.4 0.35

S17B Super 13 0.26 2.4 0.34

S18A Super 25 0.50 1.4 0.64

S19A Super 19 0.37 1.9 0.49

S19B Super 14 0.28 2.4 0.36

As shown in Exhibit 5-2 and Exhibit 5-3, all of the proposed onsite roadway sub-basins meet thedrainage criteria listed at the beginning of this section. The delineation of these onsite sub-basins andthe subsequent hydraulic results assume that the proposed inlets and storm drains described in thefollowing sections are implemented.

5.2 Onsite Proposed Inlet Hydraulics

The onsite street capacity calculations were used to identify areas that exceed the capacity of theproposed roadway. Areas that exceeded the capacity of the street require additional storm drain inletsand trunk lines to convey the flow rates in excess of the street capacity. However, the 30% preliminary


design is not intended to provide a comprehensive drainage solution for Grant Road since improving theoffsite storm drain trunk lines is outside the scope of this project. Inlets are proposed where existinginlets are located and a few locations where short laterals can connect to existing trunk lines. Wherefeasible, inlets are also proposed in critical geometric locations including but not limited to: sumplocations, super elevation transition locations (where concentrated flows will cross the street) and atintersections. The locations of each proposed inlet are provided as part of the 30% concept plansincluded as Exhibit A-7 in Appendix A.

The proposed inlets were sized to safely convey the 10-year storm event within the curb whilemaintaining an 11-foot travel lane in both directions. The proposed inlet description, depth of water,spread, and efficiency for the 10-year storm event are shown in Exhibit 5-4 for the westbound trafficsub-basins and in Exhibit 5-5 for the eastbound traffic sub-basins. The opening length shown in thesetables refers to the actual opening length; this actual length was divided by the factor of safetyrecommended in the Standards Manual for Drainage Design and Floodplain Management (City ofTucson, 1989) to derive a FlowMaster opening length to be used for calculations. The factor of safetyand other parameters pertinent to each inlet hydraulics calculation are found in Appendix K.

Exhibit 5-4 – Summary of Westbound Inlet Hydraulics

Inlet Q10 Inlet Inlet Opening Water Spread InletLocation (cfs) Condition Type Length (ft) Depth (ft) (ft) Efficiency93+76 L 14.4 On Grade Curb 19.6 0.40 20 42%

101+45 L 10.3 On Grade Curb 19.6 0.39 20 72%

101+45 L 11.1 On Grade Curb 19.6 0.33 17 57%

106+17 L 32.5 Sump Curb 19.6 1.02 50 100%

155+70 L 4.8 On Grade Curb 19.6 0.26 13 82%

174+50 L49 2.4 On Grade Curb 11.6 0.20 10 74%

174+50 L59 8.3 Sump Curb 15.6 0.42 23 100%

183+37 L 1.0 On Grade Curb 11.6 0.13 6 90%

221+81 L 0.8 On Grade Curb 11.6 0.11 6 77%

222+82 L 0.4 On Grade Curb 11.6 0.06 11 58%

223+68 L 5.5 On Grade Curb 19.6 0.22 16 64%

223+64 L 1.7 On Grade Curb 7.6 0.24 12 83%

259+37 L 8.4 On Grade Slot 40 0.39 21 80%

259+37 L 13.2 On Grade Grate 3x40 0.45 23 100%

290+98 L 14.9 On Grade Curb 19.6 0.43 22 59%

351+30 L 2.6 On Grade Curb 11.6 0.26 13 88%

355+89 L 5.2 On Grade Curb 15.6 0.34 17 85%

365+99 L 6.7 On Grade Curb 15.6 0.35 18 75%

370+31 L 6.3 Sump Curb 11.6 0.41 21 100%


Exhibit 5-5 – Summary of Eastbound Inlet Hydraulics

Inlet Q10 Inlet Inlet Opening Water Spread Inlet

Location (cfs) Condition Type Length (ft) Depth (ft) (ft) Efficiency94+00 R 6.9 On Grade Curb 19.6 0.29 15 73%

101+55 R 13.3 On Grade Curb 19.6 0.32 28 35%

106+14 L 14.4 On Grade Curb 19.6 0.37 18 39%

111+95 R 15.2 On Grade Curb 19.6 0.41 21 44%

176+59 R 7.6 On Grade Curb 19.6 0.26 24 59%

183+08 R 3.7 Sump Curb 7.6 0.40 20 100%

184+74 R 2.8 On Grade Curb 11.6 0.48 24 100%

185+71 R 4.3 On Grade Curb 15.6 0.29 20 85%

194+67 R 3.5 On Grade Curb 19.6 0.14 13 89%

195+36 R 1.6 On Grade Curb 11.6 0.16 8 80%

198+55 R 3.8 On Grade Curb 19.6 0.19 10 74%

221+74 R49 0.6 On Grade Curb 7.6 0.10 5 78%

221+74 R59 0.9 On Grade Curb 7.6 0.12 6 69%

221+82 R 0.8 On Grade Curb 15.6 0.11 6 75%

223+68 R 0.4 On Grade Curb 15.6 0.04 8 46%

233+97 R 2.8 On Grade Slot 60.0 0.19 10 98%

235+05 R 2.8 On Grade Curb 19.6 0.18 9 86%

259+71 R 7.3 On Grade Curb 19.6 0.28 24 49%

291+05 R 5.2 On Grade Curb 19.6 0.34 17 81%

365+64 R 9.3 On Grade Curb 19.6 0.32 26 49%

375+02 R 3.3 Sump Curb 7.6 0.36 18 100%

As shown in Exhibit 5-4 and Exhibit 5-5, all of the proposed inlets meet the street drainage criteriaexcept the curb inlet at station 155+70 (left). The existing storm drain system at 155+70 consists oftwin 5-foot opening curb inlets draining to a 30-inch concrete pipe that passes underneath theMcDonald’s restaurant and outlets north into an alley. Neither the existing inlets nor the existing stormdrain have adequate capacity for the 10-year design event. Installing additional inlets at this locationwill not provide additional drainage protection since the offsite storm drain would still not be able toproperly drain the proposed roadway. Therefore a single standard 19.6-foot curb opening that matchesthe curb inlets in the rest of the project is proposed to replace the existing inlets at station 155+70.Improving the offsite storm drain system is outside the scope of the 30% preliminary design but shouldbe investigated in later phases of the project.

5.3 Onsite Proposed Storm Drain Hydraulics

The 30% storm drain plan sheets show proposed storm drain laterals where the street capacity has beenexceeded by onsite runoff (within the proposed projects limits) and an offsite storm drain trunk line is


nearby. The proposed Grant Road storm drain facilities will connect to these existing offsite crossdrainage facilities. Onsite peak flow rates will be collected and conveyed downstream prior to thearrival of larger offsite peak flow rates at the Grant Road cross drainage facilities.

Proposed storm drain improvements were prepared with Bentley Inroads Suite XM Edition(V08.09.01.45) software using proposed surface grades for the rim elevations. Proposed pipes weredesigned to have minimum pipe slopes of 0.5% and minimum pipe cover of 3-feet, except where theelevation of the existing storm drain tie-in made these design goals unfeasible. The Inroads drainagefile was exported to Bentley StormCAD V8i software for hydraulic analysis of each proposed stormdrain system. The offsite storm drain trunk lines were not modeled in StormCAD, instead thedownstream hydraulic grade was set to 6-inches below the proposed roadway surface at each connectionpoint between a proposed storm drain lateral and an existing offsite trunk line. This was a conservativeassumption that ensures the proposed Grant Road storm drain laterals will continue to function withfuture improvements to the offsite storm drain systems. Results from the StormCAD computer programcan be located in Appendix L (plan view, profiles and summaries of results).

The profiles of the proposed storm drain facilities have been prepared to verify adequate cover over thepipes and that adequate fall was provided in connecting to the existing offsite cross drainage facilities.The conceptual profiles of all proposed storm drain facilities are provided in Exhibit A-7 withinAppendix A.

6. SUMMARY AND CONCLUSIONThe primary purpose of Grant Road Improvement Plan proposed onsite drainage facilities are toimprove the collection and conveyance of storm water along Grant Road to meet the City of Tucson’sdrainage design criteria. The proposed improvements will be fully analyzed as the design continues toprogress. The preliminary drainage analysis reveals that offsite cross drainage facilities are undersizedfrom Grant Road to the ultimate discharge locations and would require substantial upsizing to improvethe conditions caused by offsite drainage areas.

The roadway geometry was closely analyzed and reviewed during preliminary design to verify thatcross drainage was capable of being conveyed across Grant Road within the City of Tucson’s drainagedesign criteria. In almost all locations of offsite roadway crossings the capacities have been increased,while the capacities of cross streets to the north and south remain the same. It should be noted that themajority of these cross street conveyance capacities are exceeded by the offsite peak flow rates.Without upsizing the major offsite drainage systems, these streets conditions cannot be improved withthis project. It was the intent of this drainage study to reduce flooding within Grant Road and improveexisting roadway conditions while not making conditions worse outside the project limits.

As this project proceeds from the planning and preliminary design phases to final design, additionalhydraulic analyses will be required. These analyses include explicit offsite storm drain hydraulicanalysis to determine accurate surface flows that will cross Grant Road. This flow rate should then beapplied to a hydraulic model such as HEC-RAS to ensure the City of Tucson’s requirement of a no riseconditions of more than 0.1-ft is achieved in the construction of the proposed roadway. It is critical thatthe final design of the roadway will not result in negative impacts to downstream and upstreamproperties.

Future phases of the project will be split into six individual phases of particular intersections. Thesephases of work that will proceed through final design will be drainage independent. Each phase of the


Grant Road Improvement Plan is designed based on discrete storm drain facilities for each individualphase and thus each could be constructed independently of the other and in no particular sequence oforder.


6. REFERENCES

City of Tucson Department of Transportation. TDOT Map Center.http://dot.ci.tucson.az.us/mapcenter. Accessed May 2010.

City of Tucson Department of Transportation Engineering Division. Standards Manual for DrainageDesign and Floodplain Management in Tucson, Arizona. December 1989.

Federal Emergency Management Agency. Flood Insurance Rate Map Panel No. 04019C1638K,04019C1639K, 04019C1643K, 04019C1644K, 04019C2226K, 04019C2227K, 04019C2231K, and04019C2232K, Pima County, Arizona and Incorporated Areas. February 1999.

Federal Highway Administration. Hydraulic Design of Energy Dissipaters for Culverts and Channels(Hydraulic Engineering Circular No. 14, Third Edition). July 2006.

Kimley-Horn and Associates. Drainage Design Criteria Memorandum. Grant Road ImprovementProject. Draft August 2009.

Natural Resource Conservation Service. National Engineering Handbook. Title 201-VI, Part 630,Chapter 7, Hydrologic Soil Groups. 2009.

Pima County. Floodplain and Erosion Hazard Management Ordinance. Title 16 of the Pima CountyCode, Ordinance No. 2005-FC2. September 2005.

Pima County. Pima County Roadway Design Manual (Second Edition). December 2003.

Pima County Department of Transportation and Flood Control District. Drainage and Channel DesignStandards for Local Drainage for Floodplain Management within Pima County, Arizona. June 1984.

Pima County Geographic Information Systems. Pima County MapGuide Maps.http://www.dot.co.pima.az.us/gis/maps/mapguide. Accessed November 2009.

United States Army Corps of Engineers Hydrologic Engineering Center. HEC-1 Flood HydrographPackage (Version 4.1). June 1998.

http://dot.ci.tucson.az.us/mapcenter.

http://www.dot.co.pima.az.us/gis/maps/mapguide.


APPENDICES

098134000 Grant Road Improvement PlanOctober 2010 Preliminary Drainage Report

Appendix A – Exhibit Maps


Exhibit A-1 – Tucson Stormwater Management Study (TSMS) Nodes


Exhibit A-2 – Soils Map


Exhibit A-3 – Aerial Photograph


Exhibit A-4 – FEMA FIRM Panels


Exhibit A-5 – Existing Offsite Watershed Map


Exhibit A-6 – Drainage Onsite Sub-Basins Map


Exhibit A-7 –30% Storm Drain Plan and Profile


Appendix B – Offsite Hydrologic Data Sheets


Appendix C – Onsite Hydrologic Data Sheets


Appendix D – Offsite Storm Drain Hydraulics (Compact Disc)


Appendix E – Existing Offsite Street Hydraulics (Compact Disc)


Appendix F – Proposed Offsite Street Hydraulics (Compact Disc)


Appendix G – Existing Offsite Inlet Hydraulics (Compact Disc)


Appendix H – Proposed Offsite Inlet Hydraulics (Compact Disc)


Appendix I – Proposed Offsite Median Curb Cut Hydraulics (Compact Disc)


Appendix J – Onsite Street Hydraulics (Compact Disc)


Appendix K – Onsite Inlet Hydraulics (Compact Disc)


Appendix L – Onsite Stormdrain Hydraulics (Compact Disc)

preliminary drainage report - grant road · preliminary drainage report 098134000 grant road...

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