June 30 and July 7, 2015 - Draft Supplemental ...
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Regional Connector Transit Project Public Hearing – June 30 and July 7, 2015 Project Update
Transcript of June 30 and July 7, 2015 - Draft Supplemental ...
Regional Connector Transit Project Public Hearing – June 30 and July 7, 2015
Project Update
1. Open House
2. Presentation on SEIS Purpose and Tunneling Method Alternatives
3. Public Comments
Public Hearing Agenda
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Based on two decades of planning
and environmental review –
Final EIS was prepared for the
Locally Preferred Alternative (LPA)
approved by the Metro Board of
Directors on April 26, 2012
Federal Transit Administration
(FTA) issued a Record of
Decision (ROD) on June 29, 2012
Regional Connector Transit Project
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Per Order of the U.S. District Court issued
May 28, 2014 –
Draft Supplemental Environmental Impact
Statement (DSEIS) prepared to provide
additional detail on tunneling methods
not selected for construction along Flower
Street between 4th Street and the 7th Street/
Metro Center Station, specifically:
- Open-Face Shield
- Sequential Excavation Method (SEM)
Purpose of the SEIS
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Flower Street has major underground constraints that impact tunneling –
“Mesh” of building foundation tie-backs and many utilities
Unstable soils and challenging mixed-face geologic conditions
Perched groundwater and hazardous gases
Flower Street Segment Challenges
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Locally Preferred Alternative (LPA)
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LPA designed to address Flower Street segment challenges
EPBM tunneling north from 4th Street is most viable tunneling method given underground conditions of Flower Street segment
Cut and cover construction –
- Allows for safe removal of tie-backs
- Minimizes risk of ground loss and settlement due to unstable soils and geologic conditions
- Vents hazardous gases
- Minimizes risk of encountering utilities during construction
LPA Construction Elements
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SEIS Project Alternatives
Two tunneling method alternatives were identified to evaluate the use of other tunneling techniques on Flower Street:
Alternative A – a combination of Earth Pressure Balance Tunnel Boring Machine (EPBM), Open-Face Shield, and Sequential Excavation Method (SEM) construction methods
Alternative B – a combination of EPBM and SEM construction methods
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• Ground stabilization required for Open- Face Shield and SEM tunnel methods
• Jet grouting recommended given soil conditions on Flower Street
• Mix of cement grout and soil is injected to form a grid of 6-foot diameter columns extending 40-feet below grade
- Alternative A requires 1,900 jet holes
- Alternative B requires 1,000 jet holes
• Even with grouting, total ground stability is not assured given Flower Street underground conditions
Ground Stabilization
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Tunneling Method Alternative A
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Tunneling Method Alternative B
Construction Schedule Impacts
Comparison of Construction Schedule Impacts
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Construction Duration
Change in Construction
Duration (Over Project)
Required Pre-construction
Activities
Total Project Delivery Duration
Revenue Service Date
Total Project Delivery Delay (Over Project)
Alternative Months Months Months Months Date Months Years
The Project 78 -- -- 78 Mid-2020 -- --
Alternative A 93 15 29 122 Early-2024 44 3.7
Alternative B 85 7 29 114 Mid-2023 36 3.0
Excavation Material Handling
Excavation Activity on Flower Street and in Little Tokyo
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Impact The Project Alternative A Alternative B
Hauling of Excavated Materials from Flower Street
On Flower Street • Percentage of total Flower Street materials • Duration of hauling activities
81%
9 Months
25%
1 Month
20%
1 Month
In Little Tokyo • Percentage of total excavation activities • Duration of hauling activities
19%
2.5 Months
75%
19 Months
80%
17 Months
Excavation/Construction Trucks Per Day
On Flower Street 32 18 8
In Little Tokyo 8 22 32
Duration of Truck Impacts (for hauling excavated materials) 9 Months 19 Months 10 Months longer
17 Months 8 Months Longer
Public Comments
Public comment period through 5pm on July 27, 2015
Complete comment form
- At a Public Hearing
• June 30 at Central Library
• July 7 at JANM
- By Mail: Dolores Roybal Saltarelli, Project Manager
One Gateway Plaza, MS 99-22-2
Los Angeles, CA 90012
• Via web: www.metro.net/regionalconnector
• E-mail: [email protected]
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