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

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.)

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

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.

Photo Credit: Jeff Wong

Alto Tunnel Study - BackgroundH O W D I D W E G E T H E R E ?

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

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

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

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?

Photo Credit: Jeff Wong

Alto Tunnel Study – Geotechnical and

Structural Investigation

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

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)

Site Plan with Borehole Locations

13

Scanning Profile with Borehole Locations

Legend

- UPRR Holdings

Legend

- UPRR Holdings

Underhill Site

15

Underhill Site – Borehole Drilling

16

Underhill Site – After Drilling

17

B-1 B-2

Approximate Alto Tunnel Center LineApproximate Alto Tunnel Center Line

Chapman Site

18

Chapman Site – Borehole Drilling

19

Chapman Site – After Drilling

20

B-5 B-4 B-3

Flush Mounted Borehole Covers

21

Probe Hole Casing

Probe HolePlug

Heavy Duty Enclosure & Bolt

Down Lid

Results of Investigation

22

View from Borehole B-1

23

5”

Collapsed rock, so no scanning possible

View from Borehole B-2

24

Borehole Casing

Collapsed rock so no scanning possible

View from Borehole B-3

25

Collapsed rock so no scanning possible

Borehole Casing

View from Borehole B-4

26Water droplets visible hitting bottom of tunnel; scanning possible

View from Borehole B-5

27Void in tunnel; scanning possible

Findings of Scanning-Borehole B-4

28

Findings of Scanning Borehole B-4 Inside Tunnel, Looking East

Typical Timber Set Support Section

Findings of Scanning-Borehole B-4

29

Vertical Timber Set

Typical TimberSupport Section

Findings of Scanning-Borehole B-5

30

• 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

Cost Estimating Process:

Interpreted Tunnel Conditions

31

Cost Estimating Process:

Examples of Multi-Use Pathway

32

Cal Park Tunnel

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.

33

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

34

Examples of Reconstruction:

Intact Timber Set Sections

35

Example of Tunnel Reconstruction & Pathway:

Intact Timber Set Sections

36

Examples of Reconstruction:

Collapsed Sections

37

Example of Tunnel Reconstruction & Pathway:

Collapsed Section

38

Cost Estimating Process:

Fill and Permanent Closure

39

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

Cost Estimating Process:

Fill and Permanent Closure

40

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

Cost Estimating Process:

Interpreted Tunnel Conditions

41

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

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

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

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

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

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…

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 94903clando@marincounty.orgPhone: (415) 473-5078www.walkbikemarin.org/projects_alto.php

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