HomeMy WebLinkAboutSpec 2025-03-03 Item 5F - Contract Supplement #4 - 42nd Ave S Bridge Replacement with David Evans & Associates for $1,386,694.00COUNCIL AGENDA SYNOPSIS
Initials
Aleeting Date
Prepared by
Mayor's review
Council review
03/03/25
JR
ITEM INFORMATION
ITEM No.
S.F.
STAFF SPONSOR: ADAM COX
ORIGINAL AGENDA DATE: 03/03/25
AGENDA ITEM TITLE 42nd Ave South Bridge Replacement Project- Supplement Agreement No. 4
Contract No. 20-116, Supplement No. 4
CATEGORY ❑ Discussion
Mtg Date
M
Motion
Date
❑ Resolution
Mtg Date
❑ Ordinance
Mtg Date
❑ Bid Award
Mtg Date
❑ Public Hearing
Mtg Date
❑ Other
Mtg Date
Mtg
3/3/2025
SPONSOR ❑Council TIMayor I IHR rDCD ❑Finance ❑Fire TS 11P&R Police PIF ❑Court
SPONSOR'S This supplement will cover the remaining design and permitting work. Demolition of the
SUMMARY existing bridge is scheduled to begin in Spring 2027, and the new bridge to be open to the
public in late 2029. Council is being asked to approve supplemental agreement No. 4 for
design services with David Evans and Associates, Inc. in the amount of $1,386,694 for the
42nd Ave S Bridge Replacement Project.
REVIEWED BY
a Trans&infrastructure
❑ CommunitySvs/Safety
❑ Arts Comm.
02/24/2025
n Finance
Parks
Comm. ❑ Planning/Economic Dev.
Comm. ❑ Planning Comm.
CHAIR: JOVITA MCCONNELL
LTAC
DATE:
COMMITTEE
RECOMMENDATIONS:
SPONSOR/ADMIN.
COMMII°IEE
Public Works Department
Unanimous Approval; Forward to the Regular Consent Agenda
COST IMPACT / FUND SOURCE
EXPENDITURE REQUIRED AMOUNT BUDGETED APPROPRIATION REQUIRED
$1,386,694 $2,606,661 $0.00
Fund Source: GRANT AND CITY FUNDING
Comments: 2025 CIP — 42nd Ave S Bridge Replacement
MTG. DATE
RECORD OF COUNCIL ACTION
03/03/25
MTG. DATE
ATTACHMENTS
03/03/25
2/21/25 Info Memo - Updated on 2/27/25 after Committee meeting
2025 CIP — 42nd Ave S Bridge Replacement
Supplemental Scope of Work and Budget
Minutes from Transportation and Infrastructure Committee meeting of 02/24/25
City of Tukwila
Thomas McLeod, Mayor
Public Works Department - Pete Mayer, Interim Director
INFORMATIONAL MEMORANDUM
TO: Transportation and Infrastructure Services Committee
FROM: Pete Mayer, Interim Public Works Director
BY: Adam Cox, Transportation Program Manager
CC: Mayor Thomas McLeod
DATE: February 21, 2025
SUBJECT: 42nd Ave South Bridge Replacement Project- Supplement Agreement No. 4 No. 5
Project No. 91810404
Contract No. 20-116, Supplement No. 4 No. 5
ISSUE
Approve Supplemental Agreement No. 4 No. 5 Contract No. 20-116 with David Evans and Associates,
Inc. (DEA) for the 42nd Avenue South Bridge Replacement Project.
BACKGROUND
In September 2024, Tukwila's consultant informed the City that a supplement would be needed to
account for the remaining design/permitting work in the amount of $1,386,694.00. The project has
faced several unexpected hurdles including permitting delays, navigating culturally sensitive areas,
utility coordination, and accounting for complex site conditions. These hurdles have resulted in
additional coordination, consultation, and costs.
In August 2024, TranTech, LLC., the designer of record for the 42nd Ave S Bridge, announced they
were being acquired by David Evans & Associates, Inc. Project staff were informed the indirect cost
recovery (ICR) rate would increase once the merger occurred, and the City is now processing the
supplement to include this change. Since there is still a balance in the budget for the existing contract,
work has continued to date.
ANALYSIS
This supplement will cover the remaining design and permitting work. Demolition of the existing bridge
is scheduled to begin in Spring 2027, and we expect the new bridge to be open to the public in late
2029. Final design and permitting of the 42nd Ave S Bridge have been delayed, resulting in delayed
construction. Some of the delays are a result of design timeline extensions, unexpected geological
conditions, complex environmental, historical, and cultural requirements, 2-D hydrology analysis
requirement, customized architectural components, the discovery of different utility conditions and
associated coordination, navigating challenging constructability conditions, in -water work window
constraints, and more associated civil/ stormwater and structural design, including additional walls and
utility bridge requirements. In sum, this project has faced many hurdles, primarily related to permitting
delays and culturally sensitive areas, requiring additional coordination with the Washington State
Department of Transportation, the Department of Archeological and Historic Preservation, the
Washington Department of Fish and Wildlife, the Washington Department of Natural Resources, and
Tribes, among others. The 42nd Ave S Bridge replacement project is currently at 90% Plans and
Estimate.
Tukwila City Hall • 6200 Southcenter Boulevard • Tukwila, WA 98188 • 206-433-1800 • Website: TukwilaWA.gov
42nd Ave S Bridge Replacement Project — Supplement Agreement No. 4 No. 5
February 21, 2025
Page 2
FISCAL IMPACT
The contract for Supplement Agreement No. 4 No. 5 is to bring the 90% Plan and Estimate (P&E) to
100% Plans Specs & Estimate design in the amount of $1,386,694. The City is using funding from our
Move Ahead Washington (MAWA) grant to cover the Supplement Number costs. Supplement 1
expanded the scope of work from 30% plans and estimate to 100% bid -ready plan set, Supplement 2
provided a time extension, Supplement Number 3 accounted for a change in subconsultant, and
Supplement Number 4 accounts for the merge of TranTech, LLC to David Evans and Associates (DEA)
and adds additional $1,386,694 to the contract. DEA's scope of work and cost estimate for Supplement
4 Supplement 5 are attached.
Contract Estimate
Original Contract $1,078,487
Supplement No. 1 $1,528,174
Supplement No. 2 $0
Supplement No. 3 $0
Supplement No. /I
Supplement No. 5- 4 $1,386,694
City Funding
Puget Sound Regional
Council (PSRC) Grant
Move Ahead WA Grant
Funding Sources
$1,106,661
$1,500,000
$1,386,694
Total
$3,993,355 Total $3,993,355
RECOMMENDATION
Council is being asked to approve supplemental agreement WA- No. 5 for design services with David
Evans and Associates, Inc. in the amount of $1,386,694_for the 42nd Ave S Bridge Replacement Project
and consider this item on the Consent Agenda at the March 03, 2025 Regular Meeting.
Attachments: 42"d Ave S CIP Page
Supplemental Scope of Work and Budget
Phone: 206-433-1800 • Email: Mayor@TukwilaWA.gov • Website: TukwilaWA.gov
CITY OF TUKWILA CAPITAL PROJECT SUMMARY
2025 to 2030
PROJECT: 42nd Ave S Bridge Replacement
Project #
91810404
Project Manager Adam Cox Department Arterial Streets
DESCRIPTION:
Design and construct a replacement structure for the existing 42nd Ave S Bridge adjacent to the Tukwila Community
Center.
JUSTIFICATION:
The current bridge has been restricted to one lane for southbound traffic due to the bridge being struck by an over
height truck. The current through truss bridge is fracture critical, structural deficient, and has lasted longer than its
deign life.
STATUS:
The project is currently in the design phase, with 90% design complete. Project construction is anticipated to begin in
early 2027 and be complete by end of 2028.
MAINTENANCE IMPACT: Streets crews will be responsible to sweep the bridge and maintain any vegetation that is planted.
COMMENT:
The City has secured project costs through multiple grants- $1.5M in Surface Transportation Program funding (13.5%
match), $12M in Local Bridge Programs funding (no match), and $17M in Move Ahead Washington funding (no match).
FINANCIAL (in thousands)
2025
2026
2027
2028
2029
2030
Beyond
TOTAL
Project Costs
Project Mgmt (Staff Time/Cost)
$ 100
$ 100
$ 100
$ 50
$ -
$ -
$ -
$ 350
Design
$ 200
$ 500
$ 50
$ 50
$ -
$ -
$ -
$ 800
Land (R/W)
$ -
$ -
$ 100
$ -
$ -
$ -
$ -
$ 100
Construction Mgmt.
$ -
$ -
$ 1,500
$ 1,500
$ -
$ -
$ -
$ 3,000
Construction
$ -
$ -
$ 15,000
$ 15,000
$ -
$ -
$ -
$ 30,000
Contingency
$ -
$ -
$ 1,000
$ 1,000
$ -
$ -
$ -
$ 2,000
Total Project Costs
$ 300
$ 600
$ 17,750
$ 17,600
$ -
$ -
$ -
$ 36,250
Project Funding
Awarded Grant
$ 200
$ 500
$ 16,500
$ 14,650
$ -
$ -
$ -
$ 31,850
Proposed Grant
$ -
$ -
$ 1,150
$ 2,950
$ -
$ -
$ -
$ 4,100
Fund Balance
$ 100
$ 100
$ 100
$ -
$ -
$ -
$ -
$ 300
Total Project Funding
$ 300
$ 600
$ 17,750
$ 17,600
$ -
$ -
$ -
$ 36,250
24
Supplement No. 5 - Prime Consultant Cost Computations Summary
City of Tukwila 42nd Ave S Bridge Replacement
DEA TEAM BUDGET BREAKDOWN
11
.. w:.-;5LI L I4.7 . Fi
TranTech $ 803,573
1 Alliance $ 13,785
Facet $ 90,871
HWA Geosciences
Landau
$ 79,922
$ 104,062
Ott -Sakai $ 59,680
Transpo $ 53,084
Natural Waters
$ 55,654
TOTAL PROJECT BUDGET $ 1,260,631
MANAGEMENT RESERVE (MR) @ 10% $ 126,063
TOTAL PROJECT BUDGET + MR $ 1,386,694
25
City of Tukwila 42nd Ave S Bridge Replacement
Supplement No. 5 — Exhibit A
Scope of Work
CITY OF TUKWILA 42ND AVE S BRIDGE REPLACEMENT
INTRODUCTION
Under the 42nd Ave S Bridge Replacement project, the City of Tukwila (City) has
requested that David Evans & Associates' team (Consultant) prepare a supplement to
provide professional services to perform work not included within the original Scope
of Services and Construction Phase Engineering and Construction Management
Services.
Additional design phase services are provided by Consultant and Consultant's team
members, [geotechnical, environmental, hydraulics, bridge aesthetics and landscape
architecture, traffic engineering, and constructability], under Work Elements 1, 2, 3,
4, 5, 6, 7, 8, 10 and 12 of Supplement 4 of the contract. Work elements consisted of
additional project management, additional survey, geotechnical, environmental,
aesthetics, utility coordination, traffic signal, civil and structural design services.
These additional services are necessary as the result of design timeline extensions,
more challenging than expected geological conditions, complex environmental,
historical, and community requirements, 2-D hydrology analysis requirement,
customized architectural components, the discovery of different utility conditions and
associated coordination, challenging constructability conditions, and more associated
civil/ storm and structural design, including additional walls and utility bridge
requirements. These design revisions require additional coordination and preparation
of 90%, 100%, and Bid -Ready plans, estimates, and specifications for an additional
submittal, additional plan, estimate, and specifications.
In the following, the additional scope of work is described in further detail.
ADDITIONAL DESIGN PHASE SCOPE OF SERVICES
The additional Scope of Services described below are the work elements to be
accomplished by the Consultant as summarized under each Task. This scope consists
of the following elements:
(The task numbers below correspond to the original Scope of Services.)
26
Page 1 1
City of Tukwila 42nd Ave S Bridge Replacement
Work Element 1 —
Work Element 2 —
Work Element 3 —
Work Element 4 —
Work Element 5 —
Work Element 6 —
Work Element 7 —
(Supplemented)
Work Element 8 —
Work Element 10
Work Element 12
Project Management (Supplemented)
Surveying and Right -Of -Way (Supplemented)
Geotechnical Engineering (Supplemented)
Environmental Permitting (Supplemented)
Bridge Aesthetics and Landscape Architecture (Supplemented)
Utility Coordination (Supplemented)
Constructability Review, Construction Schedule & Estimation
Traffic Control and Traffic Signal (Supplemented)
— Hydraulics and Hydrology (Supplemented)
— PS&E (Supplemented)
The extra services are identified in the detailed Scope of Services below.
SCOPE OF SERVICES DEFINED
Task 1— Project Management (Supplemented)
This task includes project administration, meeting coordination, and design team management.
Work Elements:
• Consultant Team Meetings — approximately ninety-six (96) additional team meetings are
assumed for the additional design services.
• Monthly Progress Reports and Invoicing — approximately forty-eight (48) progress
reports containing a narrative that identifies and describes significant activities performed
in the previous month.
• Design Team Management — below is a list of continued tasks to be provided for the
duration of the additional design:
o Schedule and coordinate with the design team.
o Prepare sub -consultant agreements, coordinate, budget, and review the project
progress and submittals.
o Monitor project budget.
o Maintain regular informal contact telephone discussions and electronic mail.
Deliverables:
• Progress reports
• Monthly invoices
• Project schedule
Page
2
27
City of Tukwila 42nd Ave S Bridge Replacement
WORK ELEMENT 2 SURVEYING AND RIGHT-OF-WAY (Supplemented)
This Work Element is performed by 1 Alliance to provide survey control for bathymetry, done by
others, for the purpose of updating the existing basemap to include the Duwamish River for design
purposes.
Please see Exhibit A, Surveying Limits.
Surveying
2.1 Survey PM, Admin, QA/QC
This task includes the survey project management, administrative duties, and quality control required
for a project of this complexity and magnitude.
2.2 Survey Control
This task includes the establishment of survey control, or the recovery of existing survey control, as
required for the project. Survey control will be set, found, or referenced utilizing Real Time
Kinematic (RTK) GPS (GNSS) and the Washington State Reference Network (WSRN) in
conformance with industry standards. This survey control is then propagated, as required, utilizing
standard terrestrial total station measurements.
2.2.1. Geodetic Survey Control
• Survey work shall reference the Washington State Plane Coordinate System of 1983 as
established in accordance with Chapter 58.20 Revised Code of Washington.
• Vertical Datum shall reference the North American Vertical Datum of 1988 (NAVD88).
2.3 Field Mapping
This task includes the field surveying and mapping required for this specific effort. 1 Alliance will
survey using traditional Total Station and GPS technologies to collect the data for use in the creation
of a basemap. All found features will be located withing the mapping limits. Trees greater than 6"
DBH and/or landscaped trees will be located and will be identified as either evergreen or deciduous.
Mapping will extend across the full width of the existing Right -of -Way. Please see Exhibit A,
Surveying Limits, for specific mapping limits
2.4 Utility Surveying
Surface Observable utilities will be located as found within the surveying limits. Measure Downs for
sewer manholes, catch basins and storm drain manholes with pipe size, material, direction, and invert
elevations will be obtained, if possible, at each structure. Nearest drainage structure outside the
mapping limits will also be collected. The lowest line of overhead utilities to be located on the pole
face and, if possible, a point in or near the middle.
Underground Conductible Utility Locates will be mapped.
2.5 Office Processing
This task includes the office processing of the collected survey data, data extraction, field book note
reductions, CADD drafting, and other duties required for the generation of the deliverable(s).
Page 13
28
City of Tukwila 42nd Ave S Bridge Replacement
Assumptions:
• Rights -of -Entry will be provided by the AGENCY.
• Traffic control, if required, will be a uniformed officer and billed as an invoiced ODC.
• Tree Tags, driplines/canopies are not a part of the scope services.
• Setting of property corners is not a part of the scope of services.
• A record of Survey is not a part of the scope of services.
• Right -of -Way and boundary resolution is not a part of the scope of services.
• A private utility locating firm will be utilized by 1 Alliance. This will include Ground
Penetrating Radar (GPR).
Deliverables:
Updated topographic Survey with 1-foot contour intervals (electronic copy).
Updated AutoCAD Surfaces (DTM Files) (electronic copy).
ASCII file of control points, if requested.
Page 14
29
City of Tukwila 42nd Ave S Bridge Replacement
WORK ELEMENT 3 GEOTECHNICAL ENGINEERING (Supplemented)
This Work Element, performed by HWA Geosciences Inc. (HWA) is supplemented
to provide geotechnical engineering services.
Supplemental Geotechnical Investigation
HWA will conduct a supplemental geotechnical field investigation program. The
following tasks will be included in the program:
• Develop a Geotechnical Subsurface Exploration Plan that identifies the type,
location, and extent of proposed field explorations. This plan will also be used to
assist in development of traffic control plans.
• Prior to beginning the field exploration program, HWA will mark the proposed
exploration locations and arrange for public utility locates using the Washington
State Utility Notification Center.
• Because explorations will be located within the travel lanes or shoulders of
publicly owned streets, HWA will coordinate with the City of Tukwila to obtain
right-of-way/traffic control permits. HWA will coordinate a traffic control
subcontractor to provide appropriate traffic control personnel and devices when
working within public right-of-way.
• HWA will complete four exploratory cone penetrometer test (CPT) soundings to
provide supplemental information for use in evaluating lateral loads and design
of ground improvement (by contractor). Two CPT soundings will be located near
the north bridge approach and two CPT soundings will be located near the south
bridge approach. CPT soundings will be completed by a CPT contractor under
subcontract to HWA. HWA's subcontractor will provide a report summarizing
the results of the CPT soundings.
• Upon completion, CPT soundings will be backfilled in accordance with
Department of Ecology requirements and pavement surfaces will be patched with
fast -setting concrete.
Supplemental Geotechnical Engineering Analyses and Reporting
Information from HWA's field investigations, and those previously completed by
Landau will be analyzed by a geotechnical engineer from HWA to develop
geotechnical engineering conclusions, recommendations, and specifications for
design and construction of the proposed improvements. HWA will also discuss the
potential need for DSM near Piers 1 and 2 after attempting to refine the lateral earth
pressures near the south bridge abutment. HWA's field explorations, engineering
analyses, and geotechnical conclusions and recommendations will be summarized in
a draft geotechnical report. The draft geotechnical report will include the following:
Page 15
30
City of Tukwila 42nd Ave S Bridge Replacement
A site vicinity map and site plans identifying the approximate locations of the
explorations completed by HWA and Landau.
The report, prepared by HWA's subcontractor, documenting the results of the CPT
soundings.
Logs of explorations and laboratory testing previously completed by Landau.
A cross section along the bridge alignment that shows the anticipated geologic
conditions under and along the banks of the river.
A discussion of near surface soil and groundwater conditions observed along the
project alignment.
An evaluation of the liquefaction and lateral spreading hazards along the project
alignment.
Seismic design criteria in accordance with the American Association of State
Highway and Transportation Officials (AASHTO) LRFD Bridge Design
Specifications.
Geotechnical recommendations for the design of deep foundations for the proposed
replacement bridge as well as temporary foundation support for the existing bridge,
which will be used as a temporary bridge during construction of the replacement
bridge. The recommendations will include estimates of the following: tip elevation,
axial resistance, downdrag loads and loss of side resistance during seismic loading,
uplift resistance, lateral shaft analysis, and construction considerations.
Lateral earth pressure criteria for design of proposed bridge abutment walls and
permanent retaining walls, including equivalent fluid densities for the active, at -rest,
and passive states of stress.
Updated recommendations related to earth pressures acting on retaining walls and
bridge piers that will retain DSM-improved soil.
Updated lateral spreading loads acting on Pier 1, developed using limit equilibrium
analyses.
If needed, recommendations related to the potential for ground improvement near the
location of Pier 1, should the limit equilibrium analysis indicate that further reduction
of lateral loads are required.
Recommendations related to mechanically stabilized earth (MSE) walls along the
Green River Trail, which crosses beneath the southernmost bridge span.
Recommendations related to stormwater infiltration along the project alignment.
Recommendations related to design of flexible pavements.
Recommendations for design and construction of signal standard foundations at the
intersection of S 115th St and E Marginal Way S.
Recommendations for shallow foundation support, including subgrade preparation,
allowable soil bearing pressures, estimates of settlement, and soil parameters for
lateral load resistance (for use during design of proposed gateway structure).
Page
31
City of Tukwila 42nd Ave S Bridge Replacement
Recommendations for monitoring and testing during construction.
An appendix containing recommended specifications for construction of DSM ground
improvement at the north bridge approach.
After receipt and review of consolidated review comments from the design team, a
stamped final geotechnical report will be prepared.
ASSUMPTIONS
HWA made the following assumptions when preparing this scope of services and cost estimate:
All field tasks will be performed within or adjacent to City right-of-way. The City
will issue HWA a no cost right-of-way permit.
If it is necessary to perform field tasks outside of City right-of-way, access
permission will be obtained by others at no cost to HWA.
Due to the significance of 42nd Avenue S for freight traffic, it has been assumed that
the proposed CPT soundings will need to be completed as night work on weekdays.
HWA has assumed at least 8 hours per night will be available for on -street work.
The geotechnical field investigation will be completed under one mobilization.
The project area is assumed to be free of contamination.
Traffic control and flagging, in the form of a temporary 1-lane closure, will be
required for the proposed CPT soundings. HWA will be responsible for preparing
Traffic Control Plans (TCP). TCPs will be developed in accordance with WSDOT
standard TCPs. TCPs will be submitted to the City of Tukwila for approval and
permitting.
Traffic control will require closing the 42nd Avenue South bridge for one night.
Due to proximity to the signalized intersection of 42nd Avenue South and Interurban
Avenue S, a uniformed police officer will be required during explorations in the
vicinity of the south bridge approach.
Utility locates, completed via the Washington Utility Locate Center, will be
comprehensive and accurate enough to allow for reliable and safe location of CPT
soundings.
The City of Tukwila will allow the pavement at the CPT sounding locations to be
patched with fast -setting concrete.
Portland cement concrete pavement is not present below the asphalt concrete
pavement at the proposed CPT sounding locations (i.e., no concrete coring will be
required).
Groundwater levels at the time of the CPT soundings will be estimated based on the
CPT information that is collected.
Page 17
32
City of Tukwila 42nd Ave S Bridge Replacement
Upon completion of each CPT sounding, the soundings will be decommissioned in
accordance with the requirements of WAC 173-160.
Seismic design of the MSE wall proposed along the Green River Trail might not be
practical because it will likely be subject to liquefaction and relatively large lateral
spreading loads during the design seismic event. As such, it is assumed that seismic
design of the proposed MSE wall will not be required. If seismic design is required,
an alternative wall type will need to be considered. A budget amendment will be
required for evaluation of alternative wall types.
If the results of the additional geotechnical analyses proposed herein do not
sufficiently reduce the estimated lateral loads on Pier 1, more advanced analysis
techniques (e.g., Newmark's sliding block analysis, site response analysis, etc.) could
be performed to further refine the estimate of lateral loads. If more advanced analysis
techniques are determined to be needed, a budget amendment will be required. It will
be feasible to utilize existing geotechnical information contained in HWA's library in
developing recommendations for the proposed signal standard foundations.
Up to 16 hours has been budgeted for a Senior Geotechnical Engineer to attend
virtual meetings with the design team.
Page
8
33
City of Tukwila 42nd Ave S Bridge Replacement
WORK ELEMENT 4 ENVIRONMENTAL PERMITTING (Supplemented)
This Work Element, performed by LAI Associates, Inc., (LAI) is supplemented to
provide environmental permitting documentation support for the National
Environmental Policy Act (NEPA), the State Environmental Policy Act (SEPA), and
local permits/approvals. Federal funding is anticipated to be administered through
WSDOT Local Programs. LAI therefore assumes that the WSDOT will be the lead
coordinator for NEPA. For the purposes of this Scope of Services, LAI assumes that
this project can be authorized under a NEPA Categorical Exclusion (CE). The
necessary work elements associated with Environmental Permitting are assumed to
be:
4.3 Team and Agency Meetings
LAI will assist in scheduling and participate in meetings, as needed, with the
AGENCY, Washington State Department of Transportation (WSDOT), US Army
Corps of Engineers (USACE), Washington Department of Natural Resources, and
Washington Department of Fish & Wildlife (WDFW) to coordinate permit conditions
for the project. This task includes bi-weekly team meetings with the City and
Consultant team.
4.6 Cultural Resources
LAI will obtain the services of a qualified cultural/historic resources subconsultant to
support historic resources mitigation in compliance with Section 106 of the National
Historic Preservation Act (NHPA). The qualified cultural/historic resources
subconsultant will assist in preparing project correspondence regarding proposed
Section 106 NHPA mitigation that will be incorporated into a Memorandum of
Agreement (MOA) between the City, WSDOT Local Programs, Washington
Department of Archaeology and Historic Preservation, and affected Tribes. Upon
execution of the MOA, the subconsultant will develop the required mitigation
documents. LAI will provide support in revising subconsultant documents for
consistency with project application materials and agency coordination..
4.7 Section 4(f) Documentation
If required, LAI will support the City in developing the WSDOT Section 4(f) matrix
that will determine the content of an Individual Section 4(f) Review report. The
matrix will present an overview of project purpose and need, Section 4(f) resources,
and a least harm analysis.
Page
34
City of Tukwila 42nd Ave S Bridge Replacement
Following WSDOT concurrence on the contents of the Section 4(f) matrix, Landau
will prepare a Draft Individual Section 4(f) Review report following the WSDOT
provided outline to include:
• Introduction
• Proposed Project
• Purpose and Need
• Description of 4(f) Properties
• Alternatives Analyzed (including No Build)
• Avoidance Alternatives
• Least Harm
• Measures to Minimize Harm
• Coordination
An electronic -only (MSWord) copy of the draft report will be submitted to
Consultant/DEA and the City for review. Based on Consultant/City comments, LAI
will revise the draft and prepare a pdf of the draft report for WSDOT review and
coordination. LAI will prepare a final report following receipt of comments from
WSDOT and consulting agencies. This task includes support with agency
coordination to obtain information necessary for project concurrence.
4.12 Bidding Services
This task includes effort by LAI to provide support during bidding services and is
limited to response to questions regarding permit conditions.
Work Element 4 Assumptions:
• Team and agency meetings will occur through 2026.
• WSDOT Local Programs will prepare the Section 106 NHPA MOA.
• The determination on adverse impacts to historic resources has not been
confirmed and this task includes a not to exceed fee for mitigation documentation.
A supplement may be required upon determination of mitigation required in
accordance with the Section 106 NHPA MOA.
• Consultant will provide support in providing engineering justification for
reasonable and feasible project alternatives.
• No more than two project avoidance alternatives will be evaluated.
• This task includes support in developing at least two iterations of the Section 4(f)
matrix.
• The determination on adverse impacts to all Section 4(f) resources in the project
area has not been confirmed. This task includes a not to exceed fee for
documentation in support of Individual Section 4(f) review.
• This task includes a limited not to exceed fee for bidding support. A supplement
may be required depending on the extent of support requested during bidding.
Page 110
35
City of Tukwila 42nd Ave S Bridge Replacement
Work Element 4 Deliverables:
• Meeting participation and correspondence.
• Section 106 NHPA mitigation documentation
• WSDOT Section 4(f) matrix in Excel format.
• An electronic -only (MSWord) copy of the draft Individual Section 4(f)
Evaluation Report.
• An electronic -only (Adobe Acrobat pdf) copy of the draft Individual Section 4(f)
Evaluation Report.
• An electronic -only (Adobe Acrobat pdf) copy of the final Individual Section 4(f)
Evaluation Report.
• Bidding services correspondence as requested.
Page 111
36
City of Tukwila 42nd Ave S Bridge Replacement
WORK ELEMENT 5 BRIDGE AESTHETICS AND LANDSCAPE
ARCHITECTURE (Supplemented)
This Work Element is performed by Makers Architecture and Urban Design, LLP
(MAKERS), and a landscape architect subconsultant, (LAS) and is supplemented to
provide Bridge Aesthetics, Landscaping design, Arborist Services, and Gateway
Design. The following describes Amendment 04 for this work between
CONSULTANT and Facet (formerly DCG/Watershed,) as a landscape architect
subconsultant (hereafter referred to as LAS) to Makers Architecture and Urban
Design (SUBCONSULTANT).
Amendment 04 Scope Summary:
Amendment 04 includes services to be completed to advance Bridge Aesthetics and
Landscape Architecture, Arborist Services, and Gateway Design to 100% design. The
original project rates from 2021 are renegotiated with an anticipated completion of
scope in 2026. Scope items remaining from the agreement dated 3/13/2023, which
includes 100% plans, specifications, and estimate for Bridge Aesthetics and
Landscape Architecture, will be completed per the rates noted in this agreement.
Elements included in Amendment 04 include:
1. Updated rates for Work Element 5, Bridge Aesthetics and Landscape
Architecture
2. Arborist Services
3. 100% Gateway Design
Work Element 5. Bridge Aesthetics and Landscape Architecture
Completion of Work Element 5 scope outlined in the agreement dated 3/13/2023
using new negotiated rates.
A04.1. Tree Inventory, Impacts Assessment and Reporting
a. Inventory all significant trees (per TMC 18.06.775) located within the expanded
project (APE) area that were not inventoried as a part of Amendment 2 scope. Trees
will be tagged with a 1-1/4" aluminum tag with a unique identification number on
the trunk. Attribute information to be collected will include species, general tree
health, diameter at breast height (DBH), canopy radius (i.e. drip line) and height.
Page 112
37
City of Tukwila 42nd Ave S Bridge Replacement
All trees will be visually assessed using current Level 1 ISA standards to evaluate
current condition.
b. Trees will be identified on an annotated PDF tree sketch and attributes will be
provided on a summary table.
c. 100% site plans will be reviewed to assess anticipated impacts to individual trees
and determine which trees will likely require removal.
d. The results of the additional tree inventory and impacts assessment will be included
as an update to the arborist report, or as a report addendum, provided as a part of
Amendment 2 scope.
e. Revise Arborist Report, Tree Retention and Removal Plan, and Tree Replacement
Plan per 100% site plan revisions.
Assumptions:
• Level II or Level III arborist assessment is not included.
• Access permission for the subject properties will be obtained by Consultant.
• AutoCAD file of the site survey and 100% site plan will be provided to complete
tree impacts and removal assessment and preparation of plans.
• Final Arborist Report, Tree Retention and Removal Plan, and Tree Replacement
Plan are based upon 100% site plan including any plan revisions made in response
to draft arborist report. Additional changes to the site plan affecting tree impacts
are not included and would be covered under a separate agreement.
• The budget assumes one virtual meeting with the staff/Consultant team.
Deliverables:
• Tree Inventory Map
• Tree Inventory Table
• Revised Arborist Report or Report Addendum
• Tree Retention and Removal Plan
• Tree Replacement Plan
38
Page 113
City of Tukwila 42nd Ave S Bridge Replacement
A04.3. 100% Design for Gateway Feature
a. Work up preferred alternative at 100% design level for gateway features.
Provide drawings in a format compatible with the engineering documents.
(Format provided by the engineering team.)
b. Structural design of gateway feature.
c. Coordination with electrical engineer on lighting design.
d. Attendance at 2 public meeting to present current design to the community.
e. Attendance at 1 virtual or in person meeting with the City and Duwamish Tribe
to present current design.
Assumptions:
• All lighting, electrical, or utilities work will be by Consultant.
• The budget includes presentation at 2 public meetings organized by others.
• The budget includes one virtual or in person meeting with the City and
Duwamish Tribe organized by others.
• The engineering team will provide LAS with: CAD layouts, templates and
numbering to meet the requirements of the final bid document formatting; all
background documentation stated above or that could be useful in informing
gateway feature design.
• Coordination with respective landowners and utility managers regarding
location of gateway features shall be handled by Consultant. LAS will locate
features as directed by Consultant. Relocation of features during 100% design
that results in additional coordination, redesign and/or design modification,
and/or revisions to documentation may require additional fee.
• Redesign of gateway feature elements based on city, community, landowner, or
tribal feedback during 100% design that results in additional coordination,
redesign and/or design modification, and/or revisions to documentation may
require additional fee.
Deliverables:
• 100% documents of gateway elements of the project in digital format (CAD) as
provided by the engineering team.
• Bid -ready, stamped and signed, plans, specification, and estimate in digital
format (PDF).
Page 114
39
City of Tukwila 42nd Ave S Bridge Replacement
Work Element 6 — Utility Coordination (Supplemented)
Additional Coordination with Utilities and design and analysis services include:
6.1 Utility Coordination
During initial project scoping the AGENCY believed they owned the property
between Interurban Ave and the Duwamish River. This property is owned by Seattle
City Light (SCL). This made the coordination more time consuming, will require
additional meetings beyond the original scope, and more components are included
than franchise utilities being within AGENCY owned property and being requested to
relocate. We need to follow SCL requirements on their property. With the utilities
being on a third party owned property additional coordination was needed. We have
had 11 meetings to date, the original scope was for 12, we anticipate about 28
meetings will be needed before the plans are finalized. We have had 7 utility
meetings and 4 meetings with Districts and Stakeholders relating to utilities.
Additional coordination outside of meetings is also required due to the property
ownership. To date there have been over 100 coordination emails and calls between
utilities, districts and stakeholders. It is anticipated that at least double this amount
will be needed to complete the project.
SCL process requires approval through the Seattle City Council, permanent easement
changes, temporary easements, approval of the modified Green River Trail
configuration, artwork, tree plantings, wall configurations, trail connection to 42nd,
illumination, and other design elements will all need to be reviewed by the Council.
There will be additional effort required for all of these design elements to have
approval for work on SCL property. This will also include approval from various
SCL departments such as Electrical Engineering, Real Estate, Environmental
Engineering, Vegetation Management, and Technical Engineering divisions at a
minimum.
The coordination work for the temporary gas and temporary water to be hung from
the temporary bridge was assumed to not be part of the CONSULTANT scope. The
CONSULTANT will be including specifications to meet the utilities requirements as
a performance specification for the Contractor to follow.
The pressurized sewer line was not one of the 6 utilities considered in the original
scope and is an important element of the design because it is a 96" pressurized sewer
serving two entire cities and must be protected during construction. The line runs
parallel to Interurban and so it must be crossed with cranes and other construction
equipment and loads much be considered. Only the sewer line that crosses under the
Duwamish was a known utility when design began.
Page 115
40
City of Tukwila 42nd Ave S Bridge Replacement
WORK ELEMENT 7 CONSTRUCTABILITY REVIEW, CONSTRUCTION
SCHEDULE AND ESTIMATION (Supplemented):
This work element is performed by Ott -Sakai Construction Consultants (OS), to
provide constructability review, construction schedule, and construction estimation
services, and is supplemented as follows.
The constructability had more challenges than originally envisioned like staging areas
and major utilities on the south end of the project; erection of the long girders, and
north side soil conditions.
The work element includes the following activities:
7.3 Constructability Review and Cost Estimation 90% and Pre Ad -ready
- Supplemented
OS will provide Constructability Review, Construction Schedule and Cost Estimation
of the design team's prepared Plans, Specifications & Estimate (PS&E) package at
90% and pre -Ad -ready design levels.
7.4 Project Management / Meeting Participation
This sub task includes OS's project management with CONSULTANT, various
administrative duties, and quality control. OS will participate in internal meetings
with the design team for consultation during design of the project.
Deliverables:
• Constructability Review, Construction Schedule and Cost Estimation for
supplemented 90% and pre -Ad -ready PS&E Levels
Page 116
41
City of Tukwila 42nd Ave S Bridge Replacement
WORK ELEMENT 8 - TRAFFIC CONTROL AND TRAFFIC SIGNAL
(Supplemented):
This work element is performed by Transpo Group, Inc. (TRANSPO) to provide
traffic control, detour, and traffic signal plans for the Contractor's use in constructing
the proposed bridge and roadway improvements. The original contract is
supplemented with the following:
8.1 Traffic Analysis
No modifications and/or additions to scope.
8.2 Traffic Control
TRANSPO will prepare traffic control plans, special provisions, and engineer's
opinion of cost for constructing the proposed bridge and roadway improvements. As
noted in Supplement 02, the exact limits of the traffic control and specific plans were
unknown at the time of contracting. Supplement 02 included the following plans:
• Eight (8) short term traffic control plans
• One (1) long term traffic control plan
Since that time, the extent of traffic control needs has been further established based
on coordination with the CITY and King County, and the 90% design submittal
included the following plans:
• One (1) general notes plan
• One (1) long term traffic control overview plan
• One (1) long term traffic control plan
• One (1) long term trail plan
• One (1) detour removal plan (removing "emergency work" detour)
• Five (5) short term traffic control plans
• Four (4) traffic control detail plans
• One (5) channelization restoration plan
The plans were/will be developed to conform with MUTCD and/or WSDOT/CITY
procedures and standard plans. The Scope of Work under this Supplement 03
modifies/updates the traffic control plan deliverables.
TRANSPO will also assist the City in developing estimated travel time information
for scenarios with a temporary bridge during construction, and without a temporary
Page 117
42
City of Tukwila 42nd Ave S Bridge Replacement
bridge during construction. It is anticipated that the travel time information will be
incorporated into a PowerPoint presentation for the CITY's use.
Assumptions:
• Traffic control plans noted under Supplement 02 will not be provided.
• Traffic control plans are based on the 90% submittal package and include:
o TCP 1: General notes plan
o TCP 2: Long term plan - overview plan
o TCP 3: Long term plan - temporary staging (channelization and signing)
plans for temporary bridge bypass on 42nd Ave S between S 124th St
and Interurban Ave S.
o TCP 4: Long term plan — trail closure/diversion plan
o TCP 5: Detour removal plan
o TCP 6: Short term plan — full closure of 42nd Ave S
o TCP 7: Short term plan — full closure of Temporary 42nd Ave S
o TCP 8: Short term plan — intersection corner plan with uniformed police
officer at 42nd Ave S/Interurban Ave S
o TCP 9: Short term plan — intersection corner shoulder closure plan at
42nd Ave S/Interurban Ave S
o TCP 10: Short term plan — multiple work zone plan at 42nd Ave
S/Interurban Ave S
o TCP 11: Details — pedestrian and driveway traffic control details
o TCP 12: Details — right lane closure details
o TCP 13: Details — flagger control details
o TCP 14: Details — multi -lane closure details
o CH 1: Permanent — channelization restoration plan for Interurban Ave S
and Macadam Road S
• Long term staging plans are not required for work at the E Marginal Way S/S
115th Street intersection.
• Short term staging plans listed above will be used for work at the E Marginal
Way S/S 115th Street intersection.
• It is assumed that others will prepare all civil -related plans for temporary traffic
control. This includes, but is not limited to, the design of temporary curbs,
sidewalks, paving, grading, utilities, drainage, structures, geotechnical design,
and related work.
• Standard traffic control plans will be used to the extent feasible.
• Traffic analysis is not included in this task.
• Virtual attendance for up to two (2) meetings with the CITY is included.
Deliverables:
• Previously submitted Traffic Control package for 90% in an electronic delivery
format (PDF)
• Responses to 90% traffic control comments
• Virtual attendance for up to two (2) meetings with the CITY
Page 118
43
City of Tukwila 42nd Ave S Bridge Replacement
• Traffic Control package for 100% in an electronic delivery format (PDF)
• Stamped and Signed Ad -ready design plans in electronic format.
• Travel time information
8.3 Traffic Signal Design (42nd Ave S/Interurban Ave S)
No modifications and/or additions to scope.
8.4 Emergency Staging Design
No modifications and/or additions to scope.
8.5 Traffic Signal Design (E Marginal Way S/S 115th St)
TRANSPO will prepare traffic signal plans, special provisions, and engineer's
opinion of cost for constructing a new traffic signal system at the E Marginal Way
S/S 115th Street intersection. TRANSPO will coordinate with Puget Sound Energy
(PSE) for new electrical service for the traffic signal system. TRANSPO will
coordinate potholing for new traffic signal poles. For estimating purposes, it is
assumed up to three (3) locations will be potholed.
Assumptions:
• Traffic analysis and/or traffic signal warrant analysis is not anticipated.
• Traffic signal poles will be mast arm style.
• Special/custom signal pole foundation design is not anticipated.
• It is assumed that others will prepare all civil -related plans. This includes, but is
not limited to, the design of curbs, sidewalks, paving, grading, utilities, drainage,
structures, geotechnical design, and related work.
• The existing E Marginal Way S bridge over the Duwamish River will not be
impacted.
• Fiber optic connection and/or interconnect design to adjacent traffic signals,
traffic operations fiber-optic network, and/or traffic management center is not
anticipated.
• Video detection will be used for vehicle detection on each intersection leg.
• Streetlights will be included on the traffic signal poles, as needed, to meet
intersection lighting requirements.
• Utility relocation design, if needed, will be prepared by others.
• Up to three (3) locations will be potholed. If additional potholes are required,
this will be provided as an additional expense. Utility potholing services will be
invoiced as a project expense. The fee for potholing provided at the time of
contracting is an estimate only. If the actual cost is higher than estimated,
TRANSPO coordinate with the CITY to discuss options. Potholing for each
location will occur under the same mobilization. Repairs for potholing will be
cold mix asphalt patch, if located within concrete sidewalk or roadway. The
CITY will not charge a permitting fee for potholing.
Page 119
44
City of Tukwila 42nd Ave S Bridge Replacement
• Virtual attendance for up to one (1) meeting with the CITY is included.
• Traffic signal plans are anticipated to include:
o TS06: Traffic Signal Plan at 1"=20' scale (1 sheet)
o TS07: Traffic Signal Field Termination Plan (1 sheet)
o TS08: Traffic Signal Pole Schedule (1 sheet)
Deliverables:
• 90%, 100%, and stamped/signed ad -ready traffic signal plans in an electronic
format (PDF).
• Responses to 90% and 100% traffic signal comments.
• Virtual attendance for up to one (1) meeting with the CITY.
• Potholing data (up to three locations, as needed).
8.6 Channelization Design (E Marginal Way S/S 115th St)
TRANSPO will prepare channelization plans, special provisions, and engineer's
opinion of cost for modifying the existing channelization at the E Marginal Way S/S
115th Street intersection to support the installation of a new traffic signal system.
Assumptions:
• Traffic analysis is not anticipated.
• The existing left turn lane storage length for southbound E Marginal Way S will
not be modified.
• Channelization improvements are anticipated to primarily include installation of
new crosswalks and stop bars, and removal of existing conflicting markings.
• Channelization plans are anticipated to include:
o CH 2: Channelization Plan (1 sheet)
Deliverables:
• 90%, 100%, and stamped/signed ad -ready channelization plans in an electronic
format (PDF).
• Responses to 90% and 100% channelization comments.
Page120
45
City of Tukwila 42nd Ave S Bridge Replacement
WORK ELEMENT 10 HYDRAULICS & HYDROLOGY (Supplemented)
This Work Element replaces work element 10 in the original contract, is performed
by Natural Waters (NW) to provide Hydraulics & Hydrology services for the project.
The hydraulic and hydrology activities include the following subtasks:
10.01 Existing Data Review
NW will review existing available data and information that may be needed for the
hydraulic and scour evaluation. NW will request available information from the
AGENCY, such as: existing topography, aerial photos, bridge inspection records,
bridge plans, and anecdotal information on past flood events.
10.02 Site Reconnaissance
NW will conduct a site reconnaissance to examine the characteristics of the river,
bridge, and surrounding river corridor with respect to hydraulic, erosion, and scour
processes. The purpose of this reconnaissance is to understand site hydraulics and
channel conditions. It will be beneficial for NW to meet with the project surveyors
on site during the site reconnaissance to discuss where additional survey is needed to
support the hydraulic and scour analysis.
10.03 Hydrologic Review
The hydrology for the reach has been studied extensively by the US Corps of
Engineers. NW will review available information from the US Corps of Engineers, in
addition to available FEMA Flood Insurance Study (FIS) information, to assess
appropriate discharges, which will serve as the basis of design for the proposed water
crossing. Anticipated flows may consist of the 2-, 10-, 50-, 100-, and 500-year flood
events.
10.04 Geomorphic Assessment
NW will conduct a rapid geomorphic assessment using newly obtained survey
information, geotechnical reports, aerial photos, and findings from the field
reconnaissance. The purpose of this assessment is to determine if there have been
significant geomorphic changes over time which will need to be accounted for in the
design of the proposed water crossing.
10.05 Hydraulics
Based on review of existing data (Task 10.1) and direction from the AGENCY on
acceptable level of risk, either an existing hydraulic model developed by the US
Page I 21
46
City of Tukwila 42nd Ave S Bridge Replacement
Corps of Engineers, FEMA or another source may be used as the existing conditions
model, with minor modifications to incorporate the proposed bridge to simulate
proposed conditions. Based on the proposed crossing being located on a sharp bend,
the FHWA recommends a 2D model for assessing hydraulics at a water crossing. For
the purposes of this scope and estimate, development of a 2D model was assumed to
provide sufficient budget. All survey required for proper development of the existing
conditions hydraulic model will be performed by others and provided to NW as a
combined surface in a Land XML format in State Plane Coordinates. A proposed
combined surface, which includes the proposed bridge and grading, will be provided
by CONSULTANT in a Land XML format in State Plane Coordinates.
• Amendment 01
o The bridge design has changed since the original scope and as such
several proposed condition alternatives have been required to be
modeled to assist in the proposed project meeting FEMA no -rise
criteria. A final proposed combined surface, which includes all the
proposed project elements and grading, has been provided by
CONSULTANT in a Land XML format in State Plane Coordinates.
This final proposed combined surface will be used to finalize the 2D
hydraulic model for assessing hydraulics and scour estimates for the
final proposed design (Task 10.06).
10.06 Scour Estimates
A scour evaluation will be conducted using the hydrology and corresponding
hydraulic characteristics estimated from the hydraulic model developed in Task 10.5.
The proposed bridge is not anticipated to have any elements within the 100-yr water
surface elevation. The proposed combined surface, which includes the proposed
bridge and grading, will be provided by CONSULTANT in a Land XML format in
State Plane Coordinates. The scour estimates will be performed using this
information following the guidelines described FHWA HEC-18, 5th Edition.
10.07 Documentation
The results of the hydrologic, geomorphic, hydraulic and scour assessments will be
summarized in a brief report. The report will include a description of the physical
characteristics of the site, including photographs taken during the site reconnaissance,
along with pertinent information to support the basis of design. A draft version of the
report will be provided to CONSULTANT and the AGENCY for review and one set
of combined comments. Upon receipt of combined comments, NW will finalize the
report and submit a digital (pdf) copy, as requested by CONSULTANT and the
AGENCY.
• Amendment 01
Page 122
47
City of Tukwila 42nd Ave S Bridge Replacement
o The results from the no -rise assessment (Task 10.08) will be
summarized in the brief bridge hydraulic and scour report that includes
pertinent information to document the no -rise assessment. A separate
no -rise report is assumed to not be required.
10.08 Intentionally left blank
Amendment 01: No- Rise Assessment
The bridge design has changed since the original scope which now includes project
elements within the FEMA floodway. Since the project now includes elements within
a FEMA floodway a no -rise assessment is required. A preliminary no -rise assessment
utilizing the final proposed combined surface, which includes all the proposed project
elements and grading, provided by CONSULTANT, has been incorporated into the
2D hydraulic model developed as part of Task 10.5. The preliminary no -rise
assessment using the 2D model suggests the proposed project should meet FEMA no -
rise criteria.
The AGENCY has provided the effective FEMA 1D model to the CONSULTANT.
After review of the effective FEMA 1D model, it was recommended to the AGENCY
that the effective FEMA 1D model not be used for the no -rise assessment. The
proposed bridge is not in the best location from a hydraulics perspective due to being
on a sharp bend which does not follow the assumptions of 1D flow. This has been
verified based on the preliminary 2D hydraulic model results as the effective FEMA
1D model does not model the bridge or areas within the river bend accurately due to
flow being more 2D/3D. In addition, the cross sections that were placed in the area of
the proposed bridge by the modeler for the development of the FEMA 1D effective
model do not seem to be properly placed and there is minimal information to
determine how they were adjusted to account for the existing bridge skew. The
AGENCY corresponded with FEMA and the Department of Ecology (DOE) and
determined that the 2D hydraulic model can be used to demonstrate a no -rise for this
project. As such, this task will use the final 2D hydraulic model (Task 10.05) to
demonstrate the no -rise as it follows standard engineering practice for modeling
bridges on a skew and for rivers on sharp bends. The FEMA Effective 1D model is
inappropriate for these conditions. The 2D hydraulic model uses information from the
FEMA Effective Flood Insurance Study (FIS) dated August 19, 2020, including the
1% annual chance flood flow, floodway elevations and base flood elevations. Using
the 2D hydraulic model will also provide efficiencies by using one hydraulic model
for both the no -rise and providing hydraulic information to support the bridge design.
10.09 Permitting Assistance
NW will be available to assist with the team's preparation of permit applications and
answer questions that arise during agency review.
Page 123
48
City of Tukwila 42nd Ave S Bridge Replacement
10.10 60%/90%/100% Plans Review
NW will review river related plans at the 60%, 90%, and 100% project phases.
10.11 Project Management and Meetings
Throughout the project, NW will maintain a line of communication with the
CONSULTANT team and the AGENCY through frequent meetings and e-mails.
Various team and resource agency meetings are anticipated throughout the project
delivery process. Meetings are assumed to be virtual.
• Amendment 01 — Due to a project time extension, additional hours for project
management and meetings have been added. Meetings are assumed to be
virtual. It is assumed that hydrology and hydraulics related meetings will be
end prior to June 30, 2025.
Assumptions:
• One site visit is assumed to cover all tasks.
• A no -rise assessment or no -rise certificate (if required by AGENCY) is not
assumed to be needed and therefore is not included in the scope or budget.
■ Amendment 01
• The bridge design has changed since the original scope which now
includes project elements within the FEMA floodway. A
preliminary no -rise assessment utilizing the 2D hydraulic model
developed as part of Task 10.5 has been conducted. The preliminary
no -rise assessment utilizing the final proposed combined surface,
which includes all the proposed project elements and grading,
provided by CONSULTANT, suggests the proposed project should
meet FEMA no -rise criteria. Based on coordination with the
AGENCY, the 2D hydraulic model developed as part of Task 10.5
will be used to demonstrate a no -rise.
• No CAD related services will be performed by NW.
• Only hydrologic and hydraulic services to support the riverine aspects of the
bridge design are assumed. No other services, such as bridge drainage and
stormwater, are assumed to be needed.
• It is assumed no scour countermeasures will be required as bridge elements,
walls, roadway prism and other transportation assets will be designed to account
for total scour without the need for a scour countermeasure. If scour
countermeasures are determined to be needed, an amendment will be required.
• No large woody material or other habitat/restoration features are anticipated for
this project. If habitat restoration features are determined to be needed, an
amendment will be required.
• No plans, specifications or estimates are assumed to be needed from NW.
• CONSULTANT team will provide required geotechnical and structural
information at scheduled time to complete hydraulics and scour related tasks.
• Only one proposed condition is scoped and budgeted to be assessed and
documented in report.
Page 124
49
City of Tukwila 42nd Ave S Bridge Replacement
• Amendment 01
• The bridge design has changed since the original scope and as such
several proposed condition alternatives have been required to be
modeled to assist in the proposed project meeting FEMA no -rise
criteria. This amendment provides hours to model the final proposed
condition.
• Climate change is not anticipated to be accounted for in the hydrologic and
hydraulic analyses.
• Amendment 01
• AGENCY has stated climate change does not need to be accounted
for in the hydrologic and hydraulic analyses.
• It is assumed the project will have no change to the existing groundline and
therefore will meet AGENCY and FEMA no -rise criteria due to being within a
floodway. For these reasons, a CLOMR and LOMR is not within this scope or
estimate. If a CLOMR or LOMR is needed, an amendment will be required.
• Amendment 01
• The bridge design has changed since the original scope which now
includes project elements within the FEMA floodway. As such,
there are some modifications to the existing groundline which
includes but is not limited to a new trail location on the south side
of the proposed bridge, removal of existing piers and placement of
new piers and walls within the FEMA floodway. All other proposed
ground has been graded by CONSULTANT to match the existing
groundline. Based on a preliminary no -rise assessment utilizing the
final proposed combined surface provided by CONSULTANT, the
proposed project should meet FEMA no -rise criteria.
• It is assumed the AGENCY no -rise criteria and flood hazard code
requirements are equivalent to FEMA requirements.
• Based on coordination with the AGENCY, the 2D hydraulic model
developed as part of Task 10.5 will be used to demonstrate a no -rise.
For these reasons, a CLOMR and LOMR is not within this scope or
estimate. If a CLOMR or LOMR is needed, an amendment will be
required.
• A detailed lateral migration analysis will not be performed. A qualitative
assessment of lateral migration potential will be based on site observations and
surveyed ground information provided by the AGENCY.
• The US Corps of Engineers and the Effective FEMA hydraulic models will be
requested through or in collaboration with the AGENCY.
• AGENCY will pay any fees for acquiring US Corps of Engineers or FEMA
hydraulic models and any required permits.
• The number and level of detail of such tasks shall be performed by NW
commensurate with the level of effort allocated in the estimate.
• No hydraulic or scour analyses is assumed for any temporary features or work
access platforms within the 100-year WSE.
Page 125
50
City of Tukwila 42nd Ave S Bridge Replacement
Deliverables:
• Digital (pdf) copy of final bridge hydraulic and scour report.
• Amendment 01
• The results from the no -rise assessment (Task 10.08) will be
summarized in the brief bridge hydraulic and scour report to include
pertinent information to document the no -rise assessment. A
separate no -rise report is assumed to not be required.
Page I 26
51
City of Tukwila 42nd Ave S Bridge Replacement
Work Element 12 — PS&E (Supplemented)
Additional PS&E design and analysis services include:
12.3 & 12.4 100% and Bid -ready PS&E
As the project developed, new information where available that revised the
assumptions were made in the scoping phase, which, in turn, required efforts that
were not anticipated during the scoping phase. Additional design calculations, plans,
and opinions of cost services are included in the 90% package and will be included in
future submittals. They include:
• More Challenging -than -expected geotechnical conditions
The project as scoped assumed the proposed bridge replaces the existing
structure. The geotechnical report showed a deep liquefiable at the bridge's north
end. During the foundation design, the bridge foundation would have been too
deep (approximately 130 ft deep). Structural and geotechnical engineers worked
on refining the design and reduced the pier foundation. The design requires soil
mixing ground improvement to alleviate the lateral spread risk on the bridge
piers.
• Wall 17 at the north end of the bridge
The original scope assumed the wall at the north end is a soldier wall replacing
the failed existing sheet pile wall. The new channel survey data and geotechnical
analysis showed that the slope in front of the wall (in the river stream) would be
unstable during a large seismic event; hence, the soldier pile would lose support
and fail. Any type of wall needs to be extended below the liquefied soil layer to
satisfy safety during the earthquake. The design required a complex system,
including ground improvement, a secant pile wall supporting an MSE walls at
both ends. The additional efforts are design calculations, plan preparation for the
secant pile wall and MSE wall, and corresponding moment slabs.
• Ground Improvement
Per the above design, a ground improvement by deep soil mixing is required to
support the north end of the project. The ground improvement design was not
anticipated in the original scope. The additional efforts are plan preparations and
special specifications for the ground improvement.
• Utility Coordination
Two items were changed per the new information on the utilities:
52
Page I 27
City of Tukwila 42nd Ave S Bridge Replacement
a) Surveys showed another sewer line parallel to Interurban Ave and a
complex network of sewer lines at the south end of the bridge. This
required additional calculations to check construction loads on the utilities
and coordination meetings.
b) The north end of the detour bridge would have been close to the King
County Sewer Manhole. The concept of the detour bridge assumed access
of workers to the manhole, which is typical. However, during coordination
meetings, King County indicated that a crane access is required —
furthermore, they placed stringent requirement to drive pile near the sewer
line. Considering the risk of delay to the project and damage to the sewer
line, the design team has relocated the detour bridge further east of the
sewer. The new King County criteria effectively double the designed
effort of the detour bridge, which was not anticipated in the original scope.
• Complex environmental, historic, and social site
During the design phase of the project, the historic significance of the existing
bridge and the bridge site have changed. The changes required additional
construction and site studies, stakeholder meetings, and public involvement
meetings that were beyond the original scope of the project. So far, we have
studied and prepared the following reports:
a) Feasibility of rehabilitating and retrofitting the existing bridge.
b) Investigation of Impacts of Closing Traffic and Pedestrian Crossing.
c) Feasibility study of moving the existing bridge to build a new pedestrian
crossing upstream.
• Custom barrier, handrail, fence
The bridge design was scoped to have typical elements. The typical elements
have standard drawings and designs; as a result, they do not require engineering
design or full detailing. The plan preparations were also anticipated to follow the
typical drawings provided by WSDOT, where the details need to be revised to
match the project. The architectural components of the bridge have been beyond
the anticipated level. They require structural design to assure the components'
safety and performance. The custom details must be developed fully from the
start. The additional effort is in two parts:
a) The engineers need to design and stamp the barriers, rails, handrails, and
fences. The design efforts for the custom elements are beyond those
anticipated in the original scope.
b) Additional plan sheets are required to include the custom details. Plan sheets
in Section 12.4 would be revised as shown below:
Sheet Name
Original
PS&E
Revised
PS&E
Bridge Barrier details
3
3
Bridge Railing Details
1
2
Ped. Handrails on Bridge Railings Details
0
2
Page I 28
53
City of Tukwila 42nd Ave S Bridge Replacement
Ped. Handrails on Bridge Barrier Details
0
2
Fall Protection Fence on Walls
0
2
Custom light pole details
0
1
• Civil 3D (C3D) modeling for no -rise calculations
It was not originally anticipated that modeling of existing or proposed conditions
above or below the road would be needed and so it was not included in the
scope. The initial scope included C3D modeling for the roadway plan and profile
design only. Since the bridge was being lengthened from its existing condition it
was assumed we would not need to create models for use by the hydraulic
engineer. Additional time required included working with the existing survey
and topography to create a "combined" EG surface, a secondary "EG" surface
which showed grades after proposed demolition in order to have a base surface
for the proposed grades to tie into, a finished grade (Fg) surface also had to be
created that had more grading than what we used for the plans as it had to extend
beyond the water surface for the hydraulic model to analyze properly. There
were also meetings and emails required to make changes to the two surfaces so
they were ready for hydraulic modeling. In addition, the no -rise condition was
not met with the initial bridge design and so the bridge was modified to a wider
span and reduced pier count to ensure a "no -rise" was obtained. This resulted in
additional meetings, emails, and effort by the civil team modeling the surfaces,
the structural team to modify the structure, and they hydraulics engineer.
• Stormwater Design Criteria Changes
Since the original scope was completed, a ruling by National Marine Fisheries
Services (NMFS) has come out regarding 6-PPDq. The original assumption was
that standard treatment and flow control measures would be required for this
project, but since the NMFS ruling it was determined that 100% infiltration is the
only option to avoid a lengthy permit review process, and additional design work
is needed to meet the updated requirements.
In addition, an updated Stormwater Management Manual for Western
Washington (SWMMWW) is anticipated in June of 2024, and the King County
Stormwater Design Manual (KCSWDM) will need to be updated in response to
the SWMMWW updates. It is unknown at this time exactly what updates will be
made to the KCSWDM, but it is anticipated that these updates will impact
treatment and flow control requirements for the federal side of permitting for this
project. These requirements are anticipated to be far more stringent that what is
currently required, and will result in additional design work.
Page129
54
City of Tukwila 42nd Ave S Bridge Replacement
Stormwater Assumptions:
a) 100% infiltration of new and replaced PGIS will be required, or additional
(anticipated minimum 2 years) ESA review will be required.
b) Potential impacts of KCSWDM updates unknown at this time, but
anticipated to require additional design work similar to that required in
the 2024 SWMMWW, and potentially more stringent for ESA
compliance.
c) Additional modifications to the design will need to be made after 90%
based on new requirements.
• Specifications: The consultant revised all structural Contract Provisions
("Specifications") to incorporate the revised designs listed above.
• Estimate: Updated the opinion of cost to reflect new quantities from the
changes. Updated the unit cost to reflect current bidding climate.
• Internal QA/QC: An internal consultant quality assurance/quality control
review of deliverables will be conducted for each Pre -Ad Ready submittal
packages, as well as confirmation that comments received have been addressed.
A record of comments received will be maintained. Response to each comment
received will be tracked to confirm that they have been addressed.
Deliverables:
• 100% PS&E package
• Bid -ready PS&E Package
Page I 30
55
Transportation & Infrastructure Services Committee Minutes February24, 2025
F. Design Contract: South Boeing Access Road Overlay and Repairs
Staff is seeking approval of a contract with Psomas, Inc. in the amount of $563,983.14 for
design services.
Committee Recommendation:
Unanimous approval. Forward to March 3, 2025 Regular Meeting Consent Agenda.
G. Consultant Contract: Interurban Avenue South Overlay and Repairs
Staff is seeking approval of a contract with Psomas, Inc. in the amount of $649,418.88 for
design services.
Committee Recommendation:
Unanimous approval. Forward to March 3, 2025 Regular Meeting Consent Agenda.
H. Consultant Contract: Orillia Road South Overlay and Repairs
Staff is seeking approval of a contract with SCJ Alliance in the amount of $125,935.27 for
design services.
Committee Recommendation:
Unanimous approval. Forward to March 3, 2025 Regular Meeting Consent Agenda.
I. Supplemental Agreement: 42' Avenue South Bridge Replacement Project
*Staff is seeking approval of Supplemental Agreement No. 5, Contract No. 20-116 with David
Evans and Associates, Inc. in the amount of $1,386,694 for the remaining design/permitting
work associated with unexpected conditions on the project.
Committee Recommendation:
Unanimous approval. Forward to March 3, 2025 Regular Meeting Consent Agenda.
The meeting adjourned at 6:21 p.m.
SIT
Committee Chair Approval
Minutes by LH
56