Groundwater and Settlement Monitoring and Contingency Plan Addendum

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ENABLING WORKS CONTRACT 2 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Separable Portion 1 – Cut and Cover Works Document Ref: CRL-PAT-RME-AT-RPT-033014 Revision: 04

FINAL 30th October 2018

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

DOCUMENT INFORMATION Organisation:

Connectus

Document Title:

Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement

Fulcrum Document Number:

CRL-PAT-RME-AT-RPT-033014

Document based on iTWOcx No:

n/a

Client:

City Rail Link Limited

Project:

CRL Enabling Works: Contract Two

Location:

Auckland CBD

Project No:

2719

REVISION HISTORY Rev 01

Date 20/04/18

Details st

1 Draft for CRLL Review

Author

Approver

N. Singh

C. Hind

M. Kerr-Ridge 02

04/05/18

Final

N. Singh

C. Hind

M. Kerr-Ridge 03

03/10/18

Final – Programme Update

N. Singh

C. Hind

M. Kerr-Ridge 04

30/10/18

Final – Programme Update

M. Kerr-Ridge

C. Hind

This document remains the property of Connectus. Its contents are confidential and shall not be reproduced, destroyed or given away without the express, written permission of Connects. The electronic version of this document in iTWOcx Database on designated server(s) is the Master Copy and is a controlled document. Unless specifically noted thereon, other copies of this document are uncontrolled.

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

Table of Contents Document information .........................................................................................................................3 Revision History ..................................................................................................................................3 1

Introduction........................................................................................................................7

2

PROJECT DESCRIPTION .................................................................................................7 2.1

CONSTRUCTION METHODOLOGY OVERVIEW

2.2

CONSTRUCTION PROGRAMME OVERVIEW

3

7 10

EXISTING ENVIRONMENT ............................................................................................. 10 3.1

LAND USE AND TOPOGRAPHY

10

3.2

GEOLOGY

10

3.3

HYDROGEOLOGY

11

3.4

EXISTING BUILDINGS AND STRUCTURES

11

3.5

EXISTING BASEMENTS

11

3.6

EXISTING UTILITIES

11

4

OVERVIEW OF MONITORING & REPORTING REQUIREMENTS .................................. 11 4.1

CONSTRUCTION STAGES

11

4.2

NOTIFICATION AND GSMCP CERTIFICATION

11

4.3

DATA COLLECTION AND REPORTING REQUIREMENTS

12

4.4

INDEPENDENT BUILDING ASSESSOR (IBA) REPORTING REQUIREMENTS

12

4.5

ROLES AND RESPONSIBILITIES

12

5

GROUNDWATER MONITORING PLAN .......................................................................... 12

6

SETTLMENT MONITORING PLAN.................................................................................. 12

7

RESPONSE, MONITORING AND CONTINGENCY PLAN ............................................... 12

8

MONITORING AND CONTINGENCY PLAN REVIEW...................................................... 13

9

CUMULATIVE EFFECTS OF CRL & ADJACENT DEVELOPMENTS ............................... 13

10

CONCLUSION................................................................................................................. 13

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

1 INTRODUCTION The purpose of this Addendum to the City Rail Link (CRL) Enabling Works Contract 2 (C2) Groundwater and Settlement Monitoring and Contingency Plan1 (GSMCP) is to ensure that activities associated with the CRL C2 Public Realm Reinstatement (PRR) works meet the requirements of the conditions (resource consent 2) set out in Section 1.4 of the CRL C2 GSMCP. The specific purpose of this Addendum is to deal with potential impacts on groundwater associated with the PPR phase of the construction works that were not covered in the CRL C2 GSMCP. Where the effects from a specific activity are already covered in the CRL C2 GSMCP, reference is made to the appropriate section.

2 PROJECT DESCRIPTION This section presents a summary of the PRR works to provide context to the GSMCP Addendum. A detailed description of the PRR works is provided in the CRL C2 Construction Environment Management Plan (CEMP) – PRR Addendum (CRL-PAT-RME-AT-RPT-033021).

2.1

CONSTRUCTION METHODOLOGY OVERVIEW

Following the completion of the cut and cover trenched section of the CRL tunnel along Albert Street between Customs Street and Wyndham Street, Connectus will progress with the reinstatement of the public realm along and around the physical works area. Connectus anticipate that the completion of the cut and cover trenched section will be achieved progressively from south to north along Albert Street. Accordingly, as the tunnel is progressively completed Connectus will undertake the PRR works in a staged manner along the works area, readying Albert Street and surrounding works area for public access once again.

The PRR works include the re-instatement of the road carriageway and footpaths, urban design enhancements, and landscaping. The area for reinstatement expands beyond the works area for the cut and cover trenched section, reflecting a logical transition between the reinstated works area and surrounding public realm. Figure 1 provides an overview of the PRR works area.

These works will be undertaken using standard methods, including using jackhammers and backhoes to remove old pavements, and rollers and compactors to prepare the base course/bedding for new paving. Pavers and curb stones will be cut as required using appropriate equipment.

2.1.1

LOWER ALBERT STREET STORMWATER WORKS

A new stormwater pipe will be installed in Lower Albert Street, servicing new catch pits located along Lower Albert Street. The pipeline will be a nominal 300mm diameter and traverse a length of approximately 100m with connections to catch pits branching out along the length of the alignment.

The depth to invert of the pipeline will vary between 1.4-1.9m. The pipeline will be trenched requiring 1

Auckland City Rail Link Enabling Works Contract 2 Groundwater and Settlement Monitoring and Contingency Plan, Separable Portion 1 – Cut and Cover Works, CRL-PAT-ENV-CON-PLN-000896, Revision 05, 21-03-2016 2 Water Permit R/REG/2014/5432.

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

a <2m deep trench along a length of approximately 100m. The pipeline will connect at the northern end into a new 2.05m diameter stormwater manhole (SFMHA1). The depth to invert for the new manhole will be 2.9m requiring a <3m deep excavation to install.

2.1.1.1

Trench Excavation and Groundwater

Ground settlement due to trench excavation has been considered based on the Clough and O’Rourke (1990) method of analysis. This method states that for trench depths <2m , ground settlement of 23mm is noticed near the trench walls and negligible settlement is presented beyond 3 m distance from trench. As per the CRL C2 GSMCP (section 6.2) 2-3mm of settlement is within the tolerance for most of the utilities. Furthermore all of the buildings are >3m away from the trench hence impact on nearby building and structures are anticipated to be negligible.

Based on the relevant borehole data (BH202A, BH 302, BH403) the ground water level is 3-4m below ground level (Refer CRL C2 GSMCP). As the maximum depth of trench is <2m deep the potential effect on settlement from drawdown consolidation is negligible.

The short term fluctuation of groundwater is expected in Lower Albert Street due to tidal effect.

Dewatering is recommended during this time. Any dewatering will occur in general accordance with the summary of construction dewatering provided in Section 2.2 of the CRL C2 GSMCP. Accordingly, dewatering is anticipated to have negligible effect on ground settlement.

2.1.1.2

New Manhole (SFMHA1) Excavation and Groundwater

If sufficient space is available without clashing with buried utilities, then the ground can be cement stabilised in-situ using a standard excavator mixing the existing ground with cement. Trench shields (or similar excavation shoring measures) are still used in stabilised areas to provide a safe working area for workers.

If in-situ stabilisation cannot be carried out, then the works will need to be completed around the low tide periods, with some additional ground retention measures such as sheet piles. Sediment control measures will be in place to ensure sediment laden water is not discharged into the stormwater system. A ‘siltbuster’-type treatment device may be used to treat water from excavations to remove sediment.

Due the relatively discrete nature of the excavation required for the new manhole, settlement effects are anticipated to be comparable to those anticipated for the trench. Accordingly, dewatering is anticipated to have negligible effect on ground settlement.

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

Figure 1 - Public Realm Plan

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

2.2

CONSTRUCTION PROGRAMME OVERVIEW

The PRR works will progressively follow the completion of the cut and cover trenched section of the CRL tunnel along Albert Street between Wyndham Street and Customs Street West. As completion of the cut and cover trenched section of the CRL tunnel will occur south to north progressively along Albert Street, so too will the PRR. The exception to this is the Lower Albert Street works between Quay Street and Customs Street West which will occur first to achieve parallel construction timeframes with the Commercial Bay development.

Table 1 provides an overview of the construction staging as it relates to the PRR works. Within each area of works there will be multiple works phases (refer to the CRL C2 CEMP PRR Addendum Section 2.3 for further detail regarding the PRR construction programme).

Table 1 Construction Staging Overview Albert Street Area of works

Activity Start Date

Approximate Duration

Customs to Quay

February 2019

18 months

Wyndham to Swanson

May 2019

17 months

Swanson to Customs

January 2020

9 months

Wyndham to Mills

September 2020

2 months

Swanson to Mills

April 2020

8 months

Wolfe to Customs

January 2020

12 months

3 EXISTING ENVIRONMENT 3.1

LAND USE AND TOPOGRAPHY

There is no change to the land use and topography described in Section 3.1 of the CRL C2 GSMCP.

3.2

GEOLOGY

There is no change to the general geology identified in Section 3.2 of the CRL C2 GSMCP. Site specific geology has been determined from boreholes (BH) and other site investigations in the vicinity 34 of the CRL C2 project and has been documented in factual and interpretive reports . This includes boreholes and other site investigations on Lower Albert Street (BH202A, BH 302, BH403).

3

Aurecon, 2015a. Stage 3A Ground Investigation Factual Report. Document Ref. 228072-AC-RPT090[1], dated April 2014 4 Aurecon, 2015b. Geotechnical Engineering Report. Document Ref: CRL-SYW-GEO-000-RPT-0006 Rev 1, dated June 2015)

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

3.3

HYDROGEOLOGY

There is no change to the hydrogeology identified in Section 3.3 of the CRL C2 GSMCP. Details of the hydrogeology are provided in the CRL investigation reports referenced above and the Project Groundwater Effects Assessment5.

3.4

EXISTING BUILDINGS AND STRUCTURES

There is no change to the existing buildings and structure identification and methodology outlined in Section 3.4 of the CRL C2 GSMCP. It is noted that there are no additional buildings on Lower Albert Street that need to be included in Appendix 1 of the Resource Consent Conditions over and above those already identified. As outlined in Section 2.1.1 of this Addendum, settlement effects of the PRR works are anticipated to be negligible. Accordingly no additional building condition surveys are required in relation to the PRR works.

3.5

EXISTING BASEMENTS

There is no change to the existing basements outlined in Section 3.5 of the CRL C2 GSMCP. It is noted that the PRR works are not anticipated to change any potential post-construction groundwater mounding due to the discrete nature of excavation.

3.6

EXISTING UTILITIES

There is no change to the existing utilities outlined in Section 3.6 of the CRL C2 GSMCP.

4 OVERVIEW OF MONITORING & REPORTING REQUIREMENTS 4.1

CONSTRUCTION STAGES

There is no change to the construction stages specified in Section 4.1 of the CRL C2 GSMCP. The PRR works require discrete areas of excavation at relatively shallow depths (see Section 2.1.1).

Negligible ground settlement is noticed due to trenching and groundwater change. All the major structures are out of the zone of influence. Hence no specific monitoring is required for the PRR stage of works (beyond that already required for the cut and cover phase of works).

4.2

NOTIFICATION AND GSMCP CERTIFICATION

There is no change to the process specified in Section 4.2 of the CRL C2 GSMCP. It is noted that Auckland Council have already been notified of dewatering for the cut and cover works and the CRL C2 GSMCP has been of independently peer reviewed and certified by Auckland Council.

5

PDP, 2014. Auckland City Rail Link – Groundwater Effects Assessment – Britomart to Wyndham.

Report prepared for Aurecon on behalf of Auckland Transport, dated 17 December 2014.

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

Subject to Condition 123 of the resource consent (water permit R/REG/2014/5432) the variations to the Project GSMCP provided by this addendum shall be subject to further certification by Auckland Council (Team Leader Water Allocation, Natural Resources and Specialist Input Unit).

4.3

DATA COLLECTION AND REPORTING REQUIREMENTS

There is no change to the data collection and report requirements outlined in Section 4.3 of the CRL C2 GSMCP.

4.4

INDEPENDENT BUILDING ASSESSOR (IBA) REPORTING REQUIREMENTS

There is no change to the IBA report requirements outlined in Section 4.4 of the CRL C2 GSMCP.

4.5

ROLES AND RESPONSIBILITIES

There is no change to the roles and responsibilities listed in Section 4.5 of the CRL C2 GSMCP.

5 GROUNDWATER MONITORING PLAN There is no change to the groundwater monitoring plan detailed in Section 5 of the CRL C2 GSMCP.

6 SETTLMENT MONITORING PLAN There is no change to the settlement monitoring plan detailed in Section 6 of the CRL C2 GSMCP.

7 RESPONSE, MONITORING AND CONTINGENCY PLAN There is no change to the response, monitoring and contingency plan detailed in Section 7 of the CRL C2 GSMCP.

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Connectus 2719 Groundwater and Settlement Monitoring and Contingency Plan Addendum: Public Realm Reinstatement Project: City Rail Link C2 Doc. No. CRL-PAT-RME-AT-RPT-033014 th Client: City Rail Link Limited Revision: 4, Date: 30 October 2018

8 MONITORING AND CONTINGENCY PLAN REVIEW There is no change to the monitoring and contingency plan review processes outlined in Section 8 of the CRL C2 GSMCP.

9 CUMULATIVE EFFECTS OF CRL & ADJACENT DEVELOPMENTS There is no change to the cumulative effects of CRL and adjacent developments addressed in Section 9 of the CRL C2 GSMCP.

10 CONCLUSION The CRL C2 GSMCP provides sufficient groundwater and settlement management protocol to manage the PRR. This addendum acknowledges the existing CRL C2 GSMCP adequately caters for the nature of the PRR works. To conclude, the existing management protocol detailed in the CRL C2 GSMCP will appropriately manage groundwater and settlement related effects of construction from the PRR.

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