HomeMy WebLinkAbout18. Brown & Caldwell Proposal for 9th Avenue Reconstruction Storm Water ServicesCityof
Oshkosh
MEMORANDUM
TO: Honorable Mayor and Members of the Common Council
FROM: Mark A. Rohloff, City Manager
DATE: September 3, 2020
RE: Professional Services Agreement for West 91h Avenue Reconstruction Storm
Water Services / Brown and Caldwell ($38,536)
The City of Oshkosh (City) will be reconstructing West 91h Avenue between Linden Oaks Drive
and Oakwood Road in 2021. Within this area, storm water is currently conveyed within a grass
swales and culvert drainage system. Swales are located on both the north and south sides of West
91h Avenue and drain from west to east. Approximately one hundred feet (100') west of the
intersection of West 91h Avenue and Oakwood Road, storm water discharges from the swales,
enters an existing storm sewer system, and is conveyed to Sawyer Creek. As part of the street
construction project, the City will be replacing the storm sewer within West 9t1i Avenue between
Oakwood Road and Sawyer Creek. The West 91h Avenue reconstruction will include conversion
of the current rural cross section and swale drainage to a curb and gutter drainage system.
Wisconsin Administrative Code NR151 requires pollution control measures when streets are
converted from the natural swales to a piped system.
Additionally, with this area not having storm sewers, a hydrologic and hydraulic model of the
sub -watershed to Sawyer Creek needs to be constructed to assist in the sizing of the storm sewers
for this project. The sizing design will ensure that the ten (10) year storm event is contained
underground, the twenty five (25) year storm event allows for vehicular passage of the street, and
the one hundred (100) year storm event is fully contained within the right-of-way.
Engineering Division requested a proposal from Brown and Caldwell to conduct necessary
analyses suitable for submittal with the Project's Storm Water Notice of Intent. Brown and
Caldwell was chosen due to their extensive experience with storm water modeling and the City's
storm sewer system. The scope of services includes: water quality analysis and hydrologic and
hydraulic system modeling.
Engineering Division staff carefully reviewed the scope of services and the proposed cost, and
found that it is in line with the level of effort necessary to complete the project.
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The proposed fee is not to exceed $38,536. Funding for these services is included in the 2020
Storm Water Utility Operating Budget.
Chapter 12 of the Municipal Code of the City of Oshkosh provides that professional services of a
specialized nature, including engineering services, may be procured without the use of formal,
sealed quotes. In accordance with Section 12-16 of the Code, I am hereby submitting this report
regarding this professional services agreement.
Please contact me if you have any questions concerning this professional services agreement.
JLG/flt
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West 91hAvenue Reconstruction Storm Water Services RECEIVED
8/31/202O
ATTACHMENT A 1) pT0PpUBL|CVVOR K S'
() SB�� 0S8,VVI SC()T4 SDN
SCOPE OF SERVICES AND BUDGET
West 9mAvenue Reconstruction Storm Water Services
City of Oshkosh
City Contracb21-04
Background
The City of Oshkosh (City)will be reconstructing West 9thAvenue between Linden Oaks Drive and
Oakwood Road in2O21. Within this area, storm water is currently conveyed within a grass swale and
culvert drainage system. Gwm|moare located onboth the north and south sides ofWest 9mAvenue and
drain from west boeast. Approximately 100feet west ofthe intersection ofWest SmAvenue and
Oakwood Road, storm water discharges from the swales enters an existing storm sewer system and is
conveyed toSawyer Creek. Aepart ofthe street construction project, theQtywiUbenep|auingthesborm
sewer within West SmAvenue between Oakwood Road and Sawyer Creek.
The West 8mAvenue reconstruction will include conversion ofthacurnantnuna|oroemoecUunandowo|a
drainage toacurb and gutter drainage system. Administrative Code NR151 requires pollution control
measures when streets are reconstructed. The City requests Brown and Caldwell (9C)buconduct
necessary analyses suitable for submittal with the project's Storm Water Notice of Intent (NOI). The
analysis will evaluate water quality practices with the goal of meeting the requirements of NR 151.24(3)
for post -development total suspended solids JSS) reduction of 40 percent. The analysis will also
consider the requirements of City of Oshkosh Municipal Code Chapter 14-21 (C) Maintenance of Effort
and Section 14-21 (D) (1)T8S Reduction Standards for New Development and Redevelopment.
The City will also boinstalling aobxmoeweroonveyonoeoyobamhxUheroodway. Tosupport the storm
sewer system design, the City requests storm sewer system hydrologic and hydraulic modeling services.
The hydrologic / hydraulic modeling will be conducted using XPSWMMTm and will include all areas
tributary buthe West 0mAvenue reconstruction project area. This will include storm sewers onadjacent
streets that discharge into the West 9th Avenue right-of-way and areas west of the Project limits that also
drain into the project area.
This scope of services describes the tasks that will be conducted by BC to analyze TG8reduction
requirements and storm sewer needs for the project area (see attached Figure 1)homeet the City of
Oshkosh's water quality and conveyance goals.
The goals ofthe project are:
1. Develop Best Management Practices (BMPs) to meet TSS reduction requirements for the Project,
and
2. Size storm sewer toreplace the West SmAvenue owa|eetomeet City Storm Water conveyance
goals.
3. As part of the sizing of the West 9th Avenue storm sewer, conveyance improvements on adjacent
streets that are tributary to the West 91h Avenue right-of-way will be considered. This analysis will
allow the West 9th Avenue storm sewer to be sized to convey flows associated with future upstream
storm sewer improvements ifneeded.
Scope of Work
Tmmk1: Water Quality Analysis
1. Collect information (as provided bythe City) showing the West 8mAvenue reconstruction project
including (on scalable drawings):
o. Original road paved surface.
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b. Existing topographic data, including the areas ofexisting grass awolea.
o. Proposed new road paved surface
d. Identified portions of the project where rural road cross sections are being converted to curb
and gutter drainage.
e. Conceptual storm sewer system layout and location of catch basin inlets with sumps.
[ The City will also provide geotechnical (soil boring) information from the West g1h Avenue
reconstruction project to support WinSLAMM modeling of the existing grass swales.
2. Calculate existing T8G reduction & City cfOshkosh Municipal Coda Chapter 14TGB Reduction
Standard
a. BCwill conduct VWnGLANl[Nmodeling ofthe existing grass awa|aatoestimate the T88
reduction provided bythe current swo|eo.
b. BC will calculate the TSS reduction standard for the project based on City of Oshkosh
Municipal Code Chapter 14Table 1. The calculation will bebased onthe combination of
redevelopment and new development that iowithin the project limits.
3. Analyze Water Quality Treatment Alternatives
o. Up to three (3) alternative water quality treatment management options will be considered.
Management options may include:
i. Catch basins with sumps constructed in accordance with typical City of Oshkosh
design practices.
ii Enlarged / additional catch basins with sumps.
iii Proprietary storm water filtration devices.
iv. Biofiltration.
x Porous pavement.
vi. Swale treatment prior todischarge tostorm sewer oystem.
b. BC will develop concepts for water quality treatment and discuss the concepts with City
Staff prior tuinitial detailed evaluation.
i. Certain treatment options may not befeasible for use aepart ofthe West Sm
Avenue reconstruction project (such aoporous povamont). These treatment
practices may still baidentified and discussed. Reasons they are not feasible will
bediscussed and documented. Documentation ofall alternatives considered may
be needed if it is determined that achieving the required TSS reduction is not
feasible.
ii. Based onthe initial results, additional alternatives may beevaluated after
subsequent coordination with City Staff.
o. Conduct initial WinSLAMM modeling of the three (3) selected water quality treatment
options. Modeling will estimate the TSS reduction that can be provided by each option.
i Following initia|V0nSLAN1yN mode|ing, the results will bediscussed with City Staff.
ii. A preferred alternative will be selected in conjunction with City Staff. The City will
integrate the preferred alternative into their West 91h Avenue reconstruction plans.
d. Conduct final WinSLAMM modeling of the preferred alternative based on West 91h Avenue
reconstruction plans. The initial VVinGLAK0yNmodel for the preferred alternative will be
revised bumatch thodeeignduoumento.
4. Prepare a brief technical memo for inclusion in the City's Storm Water NOI submittal supporting the
pollution control calculations of the pre- and post-project's conditions of the West g1h Avenue
Reconstruction Project.
o. Adraft copy ofthe technical memo will bedelivered bothe City for review and comment
before finalizing the memo. The final deliverable for Task 1will include: oPOFversion of
the Technical Memo including graphics and the project VWnGLAN1yNfiles.
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Task 2:Hydrologic & Hydraulic System Modeling
1. Execute Existing Conditions Hydrologic and Hydraulic Model CXP8VVMN13CA
a. Utilize Huff & Angel (Midwest Climate Center Bulletin 71)rainfall depths and distributions.
b. Build, run, and validate model with June 12-13, 2008 rainfall amounts and soil conditions
and compare with actual observed flooding conditions tofine tune model. The City will
provide the rainfall distribution based upon the Wittman Regional Airport recording
station.
c. Perform sensitivity analysis to determine which duration design storm is the most critical
for conveyance system capacities (check the 30-minute, 1 -hour, 2-hour, and 3-hour
duration storm e/enta).
d. Utilize existing land use and coverage characteristics. Utilize data collected under Task
1.
e. Account for the tailwater effects at the West 9th Avenue outfall to Sawyer Creek
i Taikwaterlevel equal toordinary high-water mark for 1O-yeor&25-yearstorm
events.
ii Tailwater level equal bx10-yearflood elevation for 1OO-yearstorm event.
[ The XP SWMM model will include up to three (3) existing detention basins at 3250 West
9mAvenue The detention basin model input data (stage -area relationship and outlet
structure configuration) will be based on drainage plans provided by the City.
i. Run model at the critical duration for the following design storm events: 1 0-year,
25-yeor.and 1OU-year
g. Prepare color figures showing the maximum extent of flooding during each storm event.
The figures shall be color coded to show depth of flooding (typical ranges utilized are:
0.01'-0.25'. 8.26-0.5'. 0.6-1.0'. and greater than 1.0').
h. Prepare table noting the flooding depth and duration for up to (five) 5 locations for each
design storm and for the June 12-13.2DO8storm event. Locations will bedetermined
through coordination with City staff.
2. Evaluate storm water management alternatives (maximum of two (2) alternatives). The two
alternatives will consist of; 1) an initial evaluation and sizing analysis will be conducted based on
the City's conceptual storm sewer layout, and 2) a final evaluation of the City's storm sewer
design. The storm water management alternatives will be limited to conveyance system
configurations.
a. The storm sewer along the West 8thAvenue /ight-of+woywill bemodeled. The initial
storm sewers will babased onmlayout provided bythe City.
b. The sensitivity uanalysis conducted under Task 3.1.o.will beverified. Conversion from a
grass avva|edrainage system bo a storm sewer system may reduce the critical duration
for the West SmAvenue storm sewer. The 3O-minute.1'hour.2-hour.and 3-hour
duration storm events will beconsidered.
c. The existing storm sewers on adjacent roadways will be considered. Storm sewer sizes
will be increased on adjacent roadways such that the storm water conveyance goals are
met bothe maximum extent practicable. Improvements onadjacent streets will belimited
tostorm sewer replacements for this exercise. New storm sewers (on streets currently
without storm sewers), relief sewer, or detention alternatives will not be considered.
d. Flows from undeveloped areas that are tributary to the West 9th Avenue right-of-way will
be considered. For these areas, aconstant inflow equal tothe 10-yearpre-development
flow will beutilized for storm sewer sizing. This will equate tothe peak discharge rate
allowable under City of Oshkosh Municipal Code Chapter 14 for new development.
e. The proposed storm sewer will account for proper cover, tailwater elevations, and road
elevations based onthe City'mproposed roadway design. BCwill coordinate with City
Staff todetermine potential utility conflicts that need tobeconsidered. The City will
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provide information to BC based on survey information collected and roadway design
files.
f. Storm Water Conveyance Goals:
i. Eliminate street surcharging of the storm sewer system onto the street for up to
the 10-year design storm.
ii. Maintain drivability of streets (center of street "dry") for up to the 25-year design
storm.
iii. Contain runoff within the right-of-way for up to the 100-year design storm.
3. Execute the hydrologic and hydraulic model with recommended alternative.
a. Run model at the critical duration for the design storm events listed below:
i. 10-year.
ii. 25-year.
iii. 100-year.
b. Prepare color figures showing the maximum extent of flooding during each storm event.
The figures shall be color coded to show depth of flooding.
c. Run model with June 12-13, 2008 rainfall amounts and soil conditions.
d. Prepare table and/or figure showing the reduction in flooding at the five (5) locations
identified above (Task 2.1.h) for the design storms and the June 12-13, 2008 storm.
4. Prepare a brief technical memo to provide the City with the information necessary to design the
recommended storm sewers. The technical memo will contain the following topics:
a. Summary and background to the Project including goals and purpose.
b. Methodology of the analysis including:
i. Data sources.
ii. Modeling input factors and assumptions.
c. Description of the alternatives analyzed.
d. Results (tabular and graphical) of the selected alternative.
e. Description of the selected alternative including:
i. Recommended storm sewer size, material and shape.
ii. Storm Sewer invert elevations.
f. Potential regulatory issues related to the project.
g. Limitations and qualifications of the analysis and selected alternative.
A draft copy of the technical memo will be delivered to the City for review and comment before
finalizing the memo.
a. The final deliverable for Task 2 will include: a PDF version of the Technical Memo
including graphics, the project XP SWMM 2D files, and the final recommended storm
sewer alignment and size will be provided to the City in a format that can be appended to
the City's GIS files.
Task 3: Project Meetings
BC will conduct up to three (3) web -based meetings to discuss Project questions and decisions as
needed. It is anticipated that topics from both Task 1 and Task 2 will be discussed at meetings.
Schedule
The work described in the scope of services will be completed within 60 working days from receipt of all
data and files from the City. Initial analysis of alternatives (water quality and hydrologic and hydraulic
modeling) will be completed by October 15, 2020. Final evaluation and preparation of technical memos
may occur following that date, with completion by November 15, 2020.
Oshkosh 9th Ave SW Analysis Scope_2020-08-31_0.docx
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West 9*Avenue Reconstruction Storm Water Services
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Assumptions
The scope and budget for this Project were developed based onthe following conditions and
assumptions:
1. The City agrees to:
a) Meet with BC representatives,ifrequired, and make timely decisions regarding design
b} Provide all criteria and full information City requirementsfor the Project, attend Project -related
meetings, provide interim reviews on an agreed -upon schedule, make decisions on Project
alternatives, and generally participate in the Project to the extent necessary to allow BC to perform
the Services,
2. The Scope ofWork does not include:
a) Preparation of federal, ahaba, orlocal permits.
b) Survey work orany other field work.
o> Design work, or preparation of design plans.
d) Public informational meetings.
3. The City will provide all available documents, reports, and files (digital or hard copy) necessary for the
work bobeconducted. BCianot responsible for the accuracy cfthe provided files and will not
independently verify the information contained inthe files.
4. This work will be completed in 2020.
Budge
This work is conducted on a time and material, not to exceed basis per the Agreement's terms and
conditions. Brown and Caldwell assumes that nodirect material costs will baincurred onthis project.
Therefore, the budget is based on the following task breakdown, which includes labor only:
Task
Hours
Budget
Task 1: Water Quality Analysis
96.5
$13,050
Task 2: Hydrologic & Hydraulic System Modeling
165
$22,978
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