C1 presentation November 2016

City Rail Link Community Liaison Group (CLG) 22nd of November 2016

1

Overview • General update • C1 update • C2 update

• Groundwater and Settlement Monitoring and Contingency Plan (GSMCP)

General update • Funding agreement • Procurement • Industry briefing • ISCA award

C1 Update

Britomart Station Plaza update

AUG 2016

SEP 2016

OCT 2016

NOV 2016

Internal works update

C1 DSBJV Works forecast Dec – Jan summary

C2 Update

CRL- Contract 2 SP1 Groundwater and Settlement Monitoring and Contingency Plan (GSMCP) Bob Mawdsley - Connectus 22nd November 2016

What’s in the GSMCP 1. Introduction 2. Project Description 3. Existing Environment 4. Overview of Monitoring and Reporting Requirements 5. Groundwater Monitoring Plan 6. Settlement Monitoring Plan 7. Response, Mitigation and Contingency Plan 8. Monitoring and Contingency Plan Review 9. Cumulative Effects of CRL and Adjacent Developments Appendices A to F – Drawings , tables etc Appendix G – Assessment of Settlement Effects

Objectives of the GSMCP • So far as reasonably practical, avoid any damage that affects serviceability of structures and services; and • To remedy or mitigate any adverse effects (including cumulative effects) associated with dewatering and excavation activities required for the CRL tunnel construction.

Summary of Existing Infrastructure • Buildings: • Residential, historic, commercial, retail.

• Low-rise heritage shallow foundations vs. modern high rise piled structures.

• Basements: • 35 Albert St Development • Commercial Bay Development • Utilities: Less than 2 m below ground level

Existing Ground Conditions

Construction Dewatering Dewatering = • Commencing bulk excavation, or • Commencing to take water from tunnel excavation, or • Dewatering prior to excavation Regulatory mechanisms in place to mitigate potential adverse effects to the environment and infrastructure associated with construction dewatering.

Groundwater Systems • Two key groundwater systems: Groundwater System

Material Type

Water Levels

Shallow (Perched)

• Fill • Sediments

< 5 m to 15 m bgl

Deep (Regional)

Rock

• Trench excavations will be up to 18 m below ground level: • Inflows to the trench of 10 to 60 m3/day.

• Groundwater level drawdowns predicted

Introduction to Excavation Induced Ground Movement

Predicted Settlement Contours – Appendix A1

Assessment Settlement Effects – A Recap Burland Scale of Building Damage < Slight

Specimen Design (Prepared by PTA)

Predicted Settlements

Application for Resource Consents

Consent Conditions

Detailed Design (Prepared by Connectus / Aecom / McMJ)

Pre-Construction Surveys

Predicted Settlements

Building Condtion Assessments

Assessment of Settlement Effects

Compliance with Consent?

Yes

Proceed with Construction

No

Monitoring Stages • Three stages: 1. Before dewatering (baseline / pre-construction) 2. During dewatering / during constructions 3. After dewatering / post construction Dewatering = • Commencing bulk excavation, or • Commencing to take water from tunnel excavation, or • Dewatering prior to excavation

Monitoring Programme • Groundwater monitoring – boreholes / piezometers • Settlement monitoring programme: o Building Condition Surveys o Visual Inspections o Ground Movement Monitoring o Building Movement Monitoring o Structural Monitoring o Inclinometers o Strain Gauges • Soldata automated monitoring system: • Cyclops automated total stations • Geoscope database

Fig 6 - Pre-Excavation Set-up

Monitoring Illustration

Fig 7 – Routine Monitoring

Fig 8 – Response to Alerts

Fig 9 – Response to Alarms

Fig 10 – Response to Building Damage

Assessment of Cumulative Effects Concurrent Developments: • 35 Albert Street • Downtown Shopping Centre -> Commercial Bay • CRL-C2 SP2 Stormwater Diversion

Assessment of Cumulative Effects

Questions or comments?