alto tunnel investigation & cost estimate update
TRANSCRIPT
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Department of Public Works
3501 Civic Center Drive, Suite 304
San Rafael, CA 94903
415 473 6528 T / 415 473 3799 F
marincounty.org/pw
Alto Tunnel Investigation & Cost Estimate UpdateW E D N E S D A Y , S E P T E M B E R 2 7 , 2 0 1 7
6:30pm Corte Madera Community Center Community Center
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 2
Tonight’s Agenda
• Meeting Purpose (6:30-6:45 p.m.)
• Presentation (6:45—7:30 p.m.)o Background o Drilling & Scanning Processo Results of Investigation o Cost Estimate Updateo Next Steps
• Questions and Comments (7:30-8:30 p.m.)
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Slide 3
Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Meeting Purpose
• Previous direction:o Evaluate property and right-of-way issues.o Collect additional information on the tunnel interior structure.o Revise & update cost estimates based upon the above.
• Purpose of tonight’s meeting:o Recap Alto Tunnel background.o Learn how the investigation was conducted.o Learn about the updated cost estimates for optional tunnel
reconstruction and closure.o Provide comments, input & questions on the updated cost
estimates.
Photo Credit: County of Marin
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 4
Tonight’s Meeting
The Alto Tunnel Study…• Is an investigation inside the tunnel to determine its physical condition.• Is NOT a pathway feasibility study.
Therefore, at this meeting…• We WILL report on what we saw inside the tunnel and the cost estimate updates.• We will NOT discuss pros/cons of a pathway through the tunnel.
Ground rules:• Please do not interrupt presentation or responses to questions.• Please write down all questions on comment slips, one question per slip.• This will allow us to answer all questions and give us a record for website Q/A.
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Photo Credit: Jeff Wong
Alto Tunnel Study - BackgroundH O W D I D W E G E T H E R E ?
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 6
Alto Tunnel - Background
1880s-1970s: operated as a railroad1975: concrete plug and other modifications in north portal area1981: Southern portal backfilled1983: County received portions of RR right of way; tunnel ends retained by NWPRR2001: Alto Tunnel Scoping Study (Volume I, Volume II)2008-2010: Mill Valley to Corte Madera Bicycle & Pedestrian Corridor Study2013-2015: Right-of-Way Research & Land Surveying2016-2017: Current study of tunnel interior condition
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 7
Alto Tunnel - BackgroundM V - C M C O R R I D O R S T U D Y 2 0 0 8 - 1 0
Study of 3 corridors between MV & CMo Increase access & improve safety
• Route A – Horse Hill • Route B – Alto Tunnel• Route C – Camino Alto
Purpose: Give information, not select a preferred route or course of action
Funded 100% by NTPP federal grant
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 8
Alto Tunnel - BackgroundM V - C M C O R R I D O R S T U D Y - A L T O T U N N E L R O U T E
• Wornum in CM to MV-Sausalito pathway crossing of E. Blithedale in MV
Alto Tunnel: 2,173 lineal feet, 16’ wideo $40M-$50M cost (62% cont. in 2010 $s)
Tunnel segment only; no approacheso $48M-$60M along whole route
CalPark Tunnel: 1,100 lineal feet, 31’ wideo $28M construction cost; approaches included
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 9
Alto Tunnel – BackgroundR I G H T - O F - W A Y R E S E A R C H : 2 0 1 3 - 2 0 1 5 .
We found:• County holds the center
portion of the Alto Tunnel• Union Pacific RR holds the
outer ends of the Alto Tunnel
• One private owner holds the southern most end of the Alto Tunnel
Q1: Are there public rights to establish a pathway?
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Photo Credit: Jeff Wong
Alto Tunnel Study – Geotechnical and
Structural Investigation
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 11
Alto Tunnel – Background
• Q2: What’s the structural integrity of the tunnel interior?
o Will it affect the 2010 cost estimates? Investigate the areas of the tunnel we knew little about:
Center between concrete plug on north end and the pea-gravel filled area on the south end
Update cost estimates for: Reconstruction as a multi-use pathway Stabilizing the tunnel via fill & permanent closure
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 12
Geotechnical & Structural Investigation Team
• McMillen Jacobs Associates (team lead & engineers)o Drill Tech (borehole drilling)o Area West Environmental (environmental analysis)o RSE (surveying)o Renishaw (scanning)o Eisen|Letunic (outreach & communications)
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Site Plan with Borehole Locations
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Scanning Profile with Borehole Locations
Legend
- UPRR Holdings
Legend
- UPRR Holdings
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Underhill Site
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Underhill Site – Borehole Drilling
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Underhill Site – After Drilling
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B-1 B-2
Approximate Alto Tunnel Center LineApproximate Alto Tunnel Center Line
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Chapman Site
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Chapman Site – Borehole Drilling
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Chapman Site – After Drilling
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B-5 B-4 B-3
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Flush Mounted Borehole Covers
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Probe Hole Casing
Probe HolePlug
Heavy Duty Enclosure & Bolt
Down Lid
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Results of Investigation
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View from Borehole B-1
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5”
Collapsed rock, so no scanning possible
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View from Borehole B-2
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Borehole Casing
Collapsed rock so no scanning possible
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View from Borehole B-3
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Collapsed rock so no scanning possible
Borehole Casing
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View from Borehole B-4
26Water droplets visible hitting bottom of tunnel; scanning possible
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View from Borehole B-5
27Void in tunnel; scanning possible
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Findings of Scanning-Borehole B-4
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Findings of Scanning Borehole B-4 Inside Tunnel, Looking East
Typical Timber Set Support Section
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Findings of Scanning-Borehole B-4
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Vertical Timber Set
Typical TimberSupport Section
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Findings of Scanning-Borehole B-5
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• Location of borehole did not allow for compete scan
• Obtained two 2-D line scans: perpendicular and parallel to borehole orientation
• Line scans reveal that tunnel is intact at this location
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Cost Estimating Process:
Interpreted Tunnel Conditions
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Cost Estimating Process:
Examples of Multi-Use Pathway
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Cal Park Tunnel
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Basis of Design:
Tunnel Reconstruction Cost Estimate
• Entire tunnel would be lined with steel sets and smooth shotcrete lining.
• Different support and excavation methods for different sections.
• This estimate is inside tunnel work only.• Improvements outside the tunnel are not
included; pathway improvement costs outside the tunnel are identified in 2010 Mill Valley/Corte Madera Corridor Study.
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Tunnel Multi-Use Pathway Amenities
• Low Energy Lighting• Radio Communication (leaky feeder)• Emergency Call Stations at portals and
200-ft intervals• Security cameras at 300-ft intervals• Ventilation fans at 200-ft intervals• Fire alarm and pull stations • Sprinkler system in tunnel• Fire hydrants at portals and wet-
standpipes at 200-intervals• Lockable gates at portals
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Examples of Reconstruction:
Intact Timber Set Sections
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Example of Tunnel Reconstruction & Pathway:
Intact Timber Set Sections
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Examples of Reconstruction:
Collapsed Sections
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Example of Tunnel Reconstruction & Pathway:
Collapsed Section
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Cost Estimating Process:
Fill and Permanent Closure
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Primary Holes
Primary Holes:• Fill tunnel with grout through the
existing boreholes and North Portal
Primary Holes:• Fill tunnel with grout through the
existing boreholes and North Portal
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Cost Estimating Process:
Fill and Permanent Closure
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Primary Holes
Secondary Holes
Primary Holes:• Fill tunnel with grout through the
existing boreholes and North Portal Secondary Holes:
• Drill additional holes • Inspect for significant voids• Fill voids with grout
Tertiary Holes, as needed
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Cost Estimating Process:
Interpreted Tunnel Conditions
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2017 Cost Estimate Update Ranges: Tunnel Only Reconstruction & Pathway
PROJECT CONSTRUCTION COSTS 20101 (Millions) 2017 (Millions)Subtotal Construction Cost $20.5 - $25.0 $22.6 - $26.6Escalation1 $0.4 - $0.6Contingency $12.6 - $15.5 (62%) $4.4 – $5.4 (20%)
Total Construction Cost with Contingency $33.1 - $40.5 $27.0 - $32.6
PROJECT DEVELOPMENT COSTSSurvey, Technical Studies, and Engineering Design (15%) $4.2 - $5.1 $4.0 - $4.9
Environmental Analysis, Documentation, and Permits (10%) $2.8 - $3.4 $2.7 - $3.3Project Administration (10%) $2.8 - $3.4 $2.7 - $3.3Construction Management (10%) $2.8 - $3.4 $2.7 - $3.3Design Services During Construction2 $1.3Allowance to Address Right of Way Issues $0.5 - $1.5 $1.5
Total Project Development Costs $13.1- $17.1 $14.9 - $17.4
TOTAL ESTIMATED PROJECT COST $46.3 - $57.6($40.6-$50.6 in 2010 $s) $41.8 - $50.0
1 2010 costs escalated to 2017 values at 2% per year
2 Design Services during construction not included in 2010 cost estimate42
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2017 Cost Estimate Update:Tunnel Only Reconstruction & Pathway
2017 (Millions)Subtotal Construction Cost $25.0Escalation1 $0.4Contingency $5.0 (20%)
Total Construction Cost with Contingency $30.4
PROJECT DEVELOPMENT COSTSSurvey, Technical Studies, and Engineering Design (15%) $4.6Environmental Analysis, Documentation, and Permits (10%) $3.0Project Administration (10%) $3.0Construction Management (10%) $3.0Design Services During Construction2 1.3Allowance to Address Right of Way Issues $1.5
Total Project Development Costs $16.4
TOTAL ESTIMATED PROJECT COST $46.81 2010 costs escalated to 2017 values at 2% per year
2 Design Services during construction not included in 2010 cost estimate.43
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2017 Cost Estimate Update:Fill and Permanent Closure
PROJECT CONSTRUCTION COSTS 20101, (Millions) 2017(Millions)Subtotal Construction Cost $5.5 $4.5
Escalation1 $0.02
Contingency $3.6 (65%) $0.9 (20%)
Total Construction Cost with Contingency $9.0 $5.4
PROJECT DEVELOPMENT COSTSSurvey, Technical Studies, and Engineering Design (15%) $1.4 $0.8
Environmental Analysis, Documentation, and Permits (10%) $0.9 $0.5
Project Administration (10%) $0.9 $0.5
Construction Management (10%) $0.9 $0.5
Design Services During Construction2 $0.4
Allowance to Address Right of Way Issues2 $0.3
Total Project Development Costs $4.1 $3.1
TOTAL ESTIMATED PROJECT COST $13.2($11.5 in 2010 $s) $8.5
1 2010 cost escalated to 2017 values at 2% per year44
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Photo Credit: Jeff Wong
Alto Tunnel Study – Next StepsN E X T S T E P S & O T H E R W A Y S T O P A R T I C I P A T E
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 46
Next Steps
Public Comments and QuestionsTonight-comment cardsVia email or postal mail through October 11, 2017
Compiled and posted to the website
Finalize the Alto Tunnel Investigation & Cost Estimate Update: October/November 2017
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 47
After this effort is finished, what’s next?
• Neighbors, community leaders, policy makers have community conversations about options
• CM, MV, or County policy makers could make a decision to: o Initiate the Alto Tunnel Project by a local jurisdiction–Mill Valley, Corte Madera,
County, other? (Work with UPRR)o Fill and permanently close/stabilize the tunnel (Work with UPRR)o Do no further worko Further implement other alternatives from 2010 MV-CM Corridor Study: Horse Hill,
Camino Alto o Or decide to do something else…
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Department of Public Works
Alto Tunnel Study
September 27, 2017
www.walkbikemarin.org/projects_alto.php
Slide 48
Contact & Information Coordinator
Stay Informed and ParticipateSign up for updates via email & check Alto Tunnel Study webpagewalkbikemarin.org/projects_alto.php
Carey Lando, Senior Project PlannerMarin County Department of Public Works3501 Civic Center Dr., Room 304San Rafael, CA [email protected]: (415) 473-5078www.walkbikemarin.org/projects_alto.php
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Department of Public Works
3501 Civic Center Drive, Suite 304
San Rafael, CA 94903
415 473 6528 T / 415 473 3799 F
marincounty.org/pw
Photo Credit: Jeff Wong
Thank YouA L T O T U N N E L I N V E S T I G A T I O N & C O S T E S T I M A T E U P D A T E
September 27, 2017
Questions & Comments