Alto Tunnel Investigation & Cost Estimate Update WEDNESDAY, SEPTEMBER 27, 2017

6:30pm Corte Madera Community Center Community Center

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 Tonight’s Agenda

• Meeting Purpose (6:30-6:45 p.m.)

• Presentation (6:45—7:30 p.m.) o Background o Drilling & Scanning Process o Results of Investigation o Cost Estimate Update o Next Steps

• Questions and Comments (7:30-8:30 p.m.)

Department of Public Works Alto Tunnel Study 2 September 27, 2017 Slide 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. Photo Credit: County of Marin o Provide comments, input & questions on the updated cost estimates.

Department of Public Works Alto Tunnel Study 3 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php 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.

Department of Public Works Alto Tunnel Study 4 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Photo Credit: Jeff Wong Alto Tunnel Study - Background

HOW DID WE GET HERE? Alto Tunnel - Background

1880s-1970s: operated as a railroad 1975: concrete plug and other modifications in north portal area 1981: Southern portal backfilled 1983: County received portions of RR right of way; tunnel ends retained by NWPRR 2001: Alto Tunnel Scoping Study (Volume I, Volume II) 2008-2010: Mill Valley to Corte Madera Bicycle & Pedestrian Corridor Study 2013-2015: Right-of-Way Research & Land Surveying 2016-2017: Current study of tunnel interior condition

Department of Public Works Alto Tunnel Study 6 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Alto Tunnel - Background

MV-CM CORRIDOR STUDY 2008-10

Study of 3 corridors between MV & CM o 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 7 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Alto Tunnel - Background

MV-CM CORRIDOR STUDY-ALTO TUNNEL ROUTE

• Wornum in CM to MV-Sausalito pathway crossing of E. Blithedale in MV

Alto Tunnel: 2,173 lineal feet, 16’ wide o $40M-$50M cost (62% cont. in 2010 $s) . Tunnel segment only; no approaches o $48M-$60M along whole route

CalPark Tunnel: 1,100 lineal feet, 31’ wide o $28M construction cost; approaches included

Department of Public Works Alto Tunnel Study 8 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Alto Tunnel – Background RIGHT-OF-WAY RESEARCH: 2013-2015.

Q1: Are there public rights to establish a pathway?

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

Department of Public Works Alto Tunnel Study 9 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Photo Credit: Jeff Wong Alto Tunnel Study – Geotechnical and Structural Investigation 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 11 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php 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)

Department of Public Works Alto Tunnel Study 12 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Site Plan with Borehole Locations

13 Scanning Profile with Borehole Locations

Legend - UPRR Holdings Underhill Site

15 Underhill Site – Borehole Drilling

16 Underhill Site – After Drilling

B-1 B-2

Approximate Alto Tunnel Center Line

17 Chapman Site

18 Chapman Site – Borehole Drilling

19 Chapman Site – After Drilling

B-5 B-4 B-3

20 Flush Mounted Borehole Covers

Heavy Duty Enclosure & Bolt Probe Hole Down Lid Casing

Probe Hole Plug

21 Results of Investigation

22 View from Borehole B-1

5”

Collapsed rock, so no scanning possible

23 View from Borehole B-2

Borehole Casing

Collapsed rock so no scanning possible 24 View from Borehole B-3

Borehole Casing

Collapsed rock so no scanning possible 25 View from Borehole B-4

Water droplets visible hitting bottom of tunnel; 26 scanning possible View from Borehole B-5

Void in tunnel; scanning possible 27 Findings of Scanning-Borehole B-4

Findings of Scanning Borehole B-4 Typical Timber Set Support Section Inside Tunnel, Looking East 28 Findings of Scanning-Borehole B-4

Vertical Timber Set

Typical Timber Support Section

29 Findings of Scanning-Borehole B-5

• 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

30 Cost Estimating Process: Interpreted Tunnel Conditions

31 Cost Estimating Process: Examples of Multi-Use Pathway

Cal Park Tunnel 32 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

Primary Holes

Primary Holes: • Fill tunnel with grout through the existing boreholes and North Portal

39 Cost Estimating Process: Fill and Permanent Closure

Primary Holes Secondary Holes

Primary Holes: • Fill tunnel with grout through the existing boreholes and North Secondary Holes: Tertiary Holes, as needed Portal • Drill additional holes • Inspect for significant voids • Fill voids with grout 40 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 - $26.6 Escalation1 $0.4 - $0.6 Contingency $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 COSTS Survey, 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 - $3.3 Project Administration (10%) $2.8 - $3.4 $2.7 - $3.3 Construction Management (10%) $2.8 - $3.4 $2.7 - $3.3 Design Services During Construction2 $1.3 Allowance to Address Right of Way Issues $0.5 - $1.5 $1.5 Total Project Development Costs $13.1- $17.1 $14.9 - $17.4

$46.3 - $57.6 TOTAL ESTIMATED PROJECT COST $41.8 - $50.0 ($40.6-$50.6 in 2010 $s) 1 2010 costs 42escalated to 2017 values at 2% per year 2 Design Services during construction not included in 2010 cost estimate 2017 Cost Estimate Update: Tunnel Only Reconstruction & Pathway

2017 (Millions) Subtotal Construction Cost $25.0 Escalation1 $0.4 Contingency $5.0 (20%) Total Construction Cost with Contingency $30.4

PROJECT DEVELOPMENT COSTS Survey, Technical Studies, and Engineering Design (15%) $4.6 Environmental Analysis, Documentation, and Permits (10%) $3.0 Project Administration (10%) $3.0 Construction Management (10%) $3.0 Design Services During Construction2 1.3 Allowance to Address Right of Way Issues $1.5 Total Project Development Costs $16.4

TOTAL ESTIMATED PROJECT COST $46.8 1 2010 costs escalated to 2017 values at 2% per year

2 Design Services43 during construction not included in 2010 cost estimate. 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 COSTS Survey, 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 escalated44 to 2017 values at 2% per year Photo Credit: Jeff Wong Alto Tunnel Study – Next Steps

NEXT STEPS & OTHER WAYS TO PARTICIPATE Next Steps

Public Comments and Questions Tonight-comment cards Via 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 46 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php 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 work o 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 47 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Contact & Information Coordinator

Stay Informed and Participate Sign up for updates via email & check Alto Tunnel Study webpage walkbikemarin.org/projects_alto.php

Carey Lando, Senior Project Planner Marin County Department of Public Works 3501 Civic Center Dr., Room 304 San Rafael, CA 94903 [email protected] Phone: (415) 473-5078 www.walkbikemarin.org/projects_alto.php

Department of Public Works Alto Tunnel Study 48 September 27, 2017 Slide www.walkbikemarin.org/projects_alto.php Thank You ALTO TUNNEL INVESTIGATION & COST ESTIMATE UPDATE

September 27, 2017

Questions & Comments

Photo Credit: Jeff Wong

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