Groundwater and Settlement Monitoring and Contingency Plan

Karangahape Station Early Works Groundwater and Settlement Monitoring and Contingency Plan

CRL-KRD-RME-LKA-PLN-800011

Revision: Final Date: 5 November 2019

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GSMCP – Karangahape Station

Groundwater and Settlement Monitoring and Contingency Plan CRL-KRD-RME-LKA-PLN-800011

This document is uncontrolled when printed. This document should be printed in colour

Revision Status Revision

Issue Date

Major Changes

Changed By

Approved By

Rev 0

21/10/2019

Issued for Council review

George Brink

Peter Roan

Rev 1

4/11/2019

Issued for Council certification

George Brink

Peter Roan

Approval Status Name/Title Prepared by:

George Brink CRL Lead – Groundwater and Settlement

Reviewed by:

Graeme Twose Senior Geotechnical Engineer

Approved by:

Peter Roan Link Alliance Consent Lead

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Signature

Date 21/10/2019

pp

21/10/2019

21/10/2019

GSMCP – Karangahape Station

Table of contents Glossary of Terms .......................................................................................... 5 1. Introduction ............................................................................................. 6 1.1

CRL Project Description ................................................................................................. 6

1.2

Scope of CRL Project Covered by this GMSCP ................................................................. 6

1.3

GSMCP Staging .............................................................................................................. 7

1.4

Purpose of the GSMCP .................................................................................................. 7

1.4.1.

General ............................................................................................................................ 7

1.4.2.

Performance Standards during Construction ................................................................. 7

1.5

GSMCP Authors ............................................................................................................. 8

1.6

Consent Requirements .................................................................................................. 8

1.7

Sustainability .............................................................................................................. 12

1.8

GSMCP Review and updates ........................................................................................ 12

2. Project Description ................................................................................ 13 2.1

Karangahape Station Early Works ................................................................................ 13

3. Existing Environment ............................................................................. 14 3.1

Land Use and Topography ........................................................................................... 14

3.2

Geology ...................................................................................................................... 14

3.3

Hydrogeology.............................................................................................................. 15

3.4

Existing Buildings and Structures ................................................................................. 15

3.5

Existing Basements...................................................................................................... 15

3.6

Existing Utilities .......................................................................................................... 16

3.7

Issued Groundwater Diversion Consents ...................................................................... 16

4. Overview of Monitoring and Reporting Requirements ........................... 17 4.1

Monitoring and Reporting Requirements ..................................................................... 17

4.2

Notification and GSMCP Certification........................................................................... 21

4.3

Data Collection and Reporting Requirements ............................................................... 21

4.4

Independent Building Assessor Reporting Requirements .............................................. 21

4.5

Roles and Responsibilities ........................................................................................... 21

5. Groundwater Monitoring Plan ............................................................... 23 5.1

Early Works................................................................................................................. 23

6. Settlement Monitoring Plan ................................................................... 24 Page 3

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GSMCP – Karangahape Station 6.1

Introduction ................................................................................................................ 24

6.2

Building Condition Surveys .......................................................................................... 24

6.2.1.

Pre-Construction Building Condition Surveys ............................................................... 25

6.2.2.

During-Construction Building Condition Surveys.......................................................... 25

6.2.3.

Post-Construction Building Condition Surveys ............................................................. 25

6.3

Monitoring.................................................................................................................. 26

6.3.1.

Ground and Buildings .................................................................................................... 26

6.3.2.

Utilities and Infrastructure............................................................................................ 27

7. Settlement Trigger Levels ....................................................................... 29 8. Response, Mitigation and Contingency Plan........................................... 30 8.1

Introduction ................................................................................................................ 30

8.2

Response to Alerts ...................................................................................................... 30

8.2.1.

Groundwater Alerts ...................................................................................................... 30

8.2.2.

Settlement Alerts .......................................................................................................... 30

8.3

Response to Alarms..................................................................................................... 30

8.4

Response to Building or Utility Damage ....................................................................... 31

8.5

Mitigation of Effects .................................................................................................... 31

9. Monitoring and Contingency Plan Review .............................................. 33 9.1

General Review of the GSMCP ..................................................................................... 33

9.2

Review of Monitoring and Contingency Requirements ................................................. 33

APPENDIX A: Drawings ................................................................................ 34 APPENDIX B: Geological Cross Sections ........................................................ 35 APPENDIX C: Settlement Trigger Levels ........................................................ 36 APPENDIX D: Settlement Monitoring Instrumentation ................................. 37 APPENDIX E: Wall Deflection Limits to Control Settlement Effects ............... 38 APPENDIX F: Record of CLG Consultation Outcomes .................................... 39

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GSMCP – Karangahape Station

Glossary of Terms Term AT BCS CBD CEMP CEP CMJ CPEng CRL CSA ECBF EMS GNS GSMCP IBA m RL NAL

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Definition Auckland Transport Building Condition Survey Central Business District Construction Environmental Management Plan Construction Execution Plan Central Motorway Junction Chartered Professional Engineer City Rail Link Construction Support Area East Coast Bays Formation Environment & Sustainability Manager Geological and Nuclear Sciences Groundwater and Settlement Monitoring and Contingency Plan Independent Building Assessor Metres reduced level North Auckland Line

GSMCP – Karangahape Station

1.

Introduction

1.1 CRL Project Description The City Rail Link (CRL) project comprises the construction, operation and maintenance of a 3.4 km underground passenger railway, running between Britomart Station and the North Auckland Rail Line in the vicinity of Mt Eden Station. The CRL also involves the construction of two new underground stations at Aotea and Karangahape Road, and a redeveloped Mt Eden Station (Figure 1-1). The design and construction of the CRL infrastructure between the Aotea and Mt Eden Stations is being delivered by the Link Alliance.

Figure 1-1 CRL Route and Location

This Groundwater and Settlement Monitoring and Contingency Plan (GSMCP) has been prepared in relation to construction of the Karangahape Station early works.

1.2 Scope of CRL Project Covered by this GMSCP The Karangahape Station consists of two entrances, one at Beresford Square / Pitt Street and the other at Mercury Lane, linked together by platforms with two mined tunnels approximately 32m below Pitt Street. The Station will also comprise equipment rooms, ventilation systems and emergency egress at both Mercury Lane and Beresford Square / Pitt Street.

Given the nature and scale of the Karangahape Station construction, works will be undertaken in a staged manner, involving:

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

Early works (demolition, network utility relocation and site establishment works) – to be undertaken from September 2019 through to early 2020;



Main construction works (construction of the station and mined tunnels for the rail tracks) – to be undertaken from early 2020 through to late 2023; and

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GSMCP – Karangahape Station 

Public realm reinstatement – from late 2022 to late 2024.

1.3 GSMCP Staging To reflect the staged construction approach for the Karangahape Station, the GSMCPs for this area will be developed in stages. This GSMCP has been prepared in relation to the early works only, which are described in detail in the Construction Environmental Management Plan (CEMP) and summarised in Section 1.7 of this GSMCP. A separate GSMCP will be prepared for the Karangahape Station main construction works.

1.4 Purpose of the GSMCP 1.4.1. General The purpose of this GSMCP is to, so far as reasonably practical: 

Prevent damage that may affect the serviceability of structures and services, and



Provide appropriate measures to remediate or mitigate any adverse effects (including cumulative effects) as a result of the dewatering and excavation activities involved in the early works.

This GSMCP addresses the relevant matters specified in the conditions of Water Permit R/REG/2016/1892 (groundwater diversion and discharge) (‘the Consent’).

This GSMCP forms part of the CEMP for the Karangahape Station early works. The majority of the relocation works will be carried out in shallow trenches which do not need excavation support and are not further considered in this GSMCP. The relocation of the wastewater and stormwater lines will however involve deep excavations for which mechanical settlement effects need to be considered. These include: 

  

The excavation of two launch shafts in Pitt Street (4 m x 3 m, maximum depth of 5 m bGL) and recovery shafts in Beresford Square (3m x 3m, maximum depth 3.5m bGL) at either end of the wastewater or stormwater line to be relocated; Directional drilling (approximately 300 mm diameter bore) of the distance between shafts; Rigging of the new pipe (250 mm diameter) through the drilled route; and Installing cased manholes (1.15 m diameter, maximum depth of 5 m bGL) along the length of the route along Beresford Square and at the positions of the launch shafts once work has been completed.

The GSMCP has been developed in consultation with the Karangahape Community and Business Liaison Group (CLG) (as per Resource Consent Condition 16 and 19). Comments received from the CLG have been (where applicable and appropriate) incorporated in the GSMCP, with an explanation provided where any comments have not been incorporated. A record of the consultation outcomes is provided in Appendix F of this GSMCP.

1.4.2. Performance Standards during Construction Consent Conditions 83 and 84 specify the performance standards with respect to settlement that apply during the works, including:

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GSMCP – Karangahape Station 

Within the 5 mm settlement contours on the drawings in Appendix 1 (of the Consent), all excavations, dewatering systems, retaining structures and associated works (including backfilling) for the CRL construction must be designed, constructed and maintained so as to avoid any damage that exceeds the Serviceability Limits of buildings, structures and services.



Beyond the 5 mm settlement contours on the drawings in Appendix 1, the Consent Holder must ensure that the damage to masonry buildings due to the Project works does not exceed the “negligible damage” category extent detailed in Table 1 of the Consent, and has only negligible effects on piled buildings, structures and services.

These performance standards will be achieved through the specific design aspects of the early works, and by the contingency measures associated with the design, described in Sections 5, 6, 8 and Appendix E of this GSMCP. The estimated potential ground surface settlements from the early works are evaluated in the memorandum attached as Appendix E. Provided that the excavation support is designed so that any structural deflection does not exceed the maximum tolerable deflections outlined in Appendix E, ground surface settlements as a result of the early works should not exceed the trigger levels outlined in the Consent for the adjacent structures.

1.5 GSMCP Authors This GSMCP has been prepared by a senior qualified person (Geotechnical Professional), George Brink (PhD Engineering Geology).

George is an Engineering Geologist with Tonkin and Taylor in Auckland, New Zealand. He has 10 years’ experience in the geotechnical characterisation and evaluation of soil and rock mass behaviour, as well as undertaking, managing, and reporting on geotechnical investigations for a number of international public and private sector clients.

This GSMCP has been reviewed by a senior qualified person (Geotechnical Professional), Graeme Twose, NZCE (Civil), BE (Civil, Hons).

Graeme is a Senior Geotechnical Engineer with Tonkin and Taylor in Auckland, New Zealand. He has over 20 years’ experience and has specialised in groundwater and settlement assessments for tunnels and deep excavations - with a particular focus on Auckland geology. His involvement in tunnelling and deep excavation projects spans investigation and feasibility stages, through to construction monitoring and contingency planning.

1.6 Consent Requirements Table 1-1 outlines a summary of the resource consent conditions relevant to this GSMCP and where they are addressed in the document.

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GSMCP – Karangahape Station Table 1-1 Relevant GSMCP conditions

Consent Condition 83 Performance Standards

84 90 91

Appointment of IBA

92 93

Pre-dewatering Services Survey

94 95 96 97 98 99

Brief Condition Description

Section Addressed in

Within the 5mm settlement contours in Appendix 1 of the Consent, all excavations, dewatering systems, retaining structures and associated works (including backfilling) for the CRL construction must be designed, constructed and maintained to avoid any damage that exceeds the Serviceability limits of buildings, structures and services.

Section 1.4.2

Beyond the 5mm settlement contours on the drawings in Appendix 1, the Consent Holder must ensure that the damage to masonry buildings due to the Project works, including excavations, dewatering systems, retaining structures and associated works (including backfilling), does not exceed the “negligible damage” category extent detailed in Table 1 of the Consent and has only negligible effects on piled buildings, structures and services.

The Consent Holder shall ensure that there is no long-term mounding due to damming of groundwater by the proposed rail infrastructure.

Prior to the Consent Holder submitting the GSMCP under Condition 97, the Consent Holder shall request that Council engage, at the cost of the Consent Holder, a suitably qualified independent specialist, agreed to by the Consent Holder, to fill the role of Independent Building Assessor (IBA). The Consent Holder shall acknowledge that the IBA can, at the expense of the Consent Holder, engage other independent specialists, but only in consultation with the Consent Holder.

The IBA required by Condition 91 shall report to the Manager on building damage matters and how these matters may be addressed by the Consent Holder.

Prior to the Commencement of Dewatering, and following the identification of potentially affected Services, the Consent Holder shall, in consultation with the relevant service provider, undertake a condition survey of all such Services. This condition does not apply to any Service where written evidence is provided to the Manager that the owner of that Service has confirmed they do not require a condition survey.

The monitoring of any settlement effects on those potentially affected Services shall be in accordance with Conditions 120 and 121.

In the event that the Services’ trigger levels in Appendix 2 are breached, the Consent Holder must carry out remedial actions in accordance with Conditions 125 and 128.

GSMCP requirements for certification by Auckland Council (timeframes and peer review) Dewatering is not to commence until certification from the Manager is provided.

The GSMCP, required by Condition 97, shall include the requirements of the Consent including, but not limited to, the following: a. an “as built” survey plan of all monitoring locations based on approximate positions located on the plans entitled: • A02502731, Figure 39, Rev B dated May 2016 and ET Table 7.1 (Appendix 3); and • The plans referred to in Appendix 1 and any further building-specific monitoring requirements determined from the detailed pre-construction building condition assessment. b. full details (frequency and scope) of groundwater (including construction logs), ground surface, building, retaining wall, building façade, inclinometer monitoring programme and conditions surveys, and frequency and scope of visual inspections required by this consent

Groundwater and Settlement Monitoring and Contingency Plan ("GSMCP")

100

c. a bar chart, such as a Gantt chart, showing the timing and frequency of the condition surveys and monitoring required by this consent relative to the Commencement of Dewatering and the Completion of Dewatering; d. groundwater alert triggers e. details of all alert and alarm triggers (including any necessary horizontal and vertical displacements), the frequency of monitoring and the criteria to cease monitoring for each ground, building and retaining wall deformation marks and inclinometers, extensometers. The alert and alarm triggers shall be an update of the provisional triggers provided on drawings CRL-SYW-RME-000-DRG-2640 Rev 4. dated 14 October 2016 and CRL-SYW-RME-000-DRG-2642 Rev 3. dated 11 October 2016. f. details of contingency measures to be implemented if alert or alarm triggers are exceeded including a Response Plan. g. identification of any adjacent services susceptible to damage and details of any pre and post construction monitoring or inspection;

101 102 103 Groundwater Monitoring Page 9

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i. details of monitoring proposed to be undertaken to protect the issued groundwater diversion consents listed in the Consent Conditions against cumulative settlement effects; j. identification of existing basements which could be subject to potential flooding from post-construction groundwater mounding; details of monitoring of long-term groundwater mounding effects; and details of groundwater drain construction to prevent groundwater mounding k. the review of the proposed alarm and alert trigger levels in Appendix 2, approved by the IBA, following the pre-construction building condition surveys (required by Condition 109) that confirms they are set to ensure Serviceability Limits will be not be exceeded and whether the monitoring frequency is adequate, possibly requiring further site investigation work where sensitive structures are identified as part of Condition 112 The GSMCP may be varied, including frequency of monitoring, subject to the certification by Auckland Council, which is contingent on approval by the IBA. Once certified, the GSMCP shall be implemented for the periods specified in the conditions of the Consent.

The Consent Holder shall advise the Manager, in writing, of the date of the proposed Commencement of Dewatering.

The Consent Holder shall install, maintain and replace if necessary, groundwater monitoring boreholes listed in Appendix 3 of this consent and shown on drawing A02502731, Figure 39, Rev B dated May 2016 (Appendix 3) and ET Table 7.1 (Appendix 3) of this consent, for the period required by the conditions of this consent.

The Consent Holder shall measure and record groundwater levels at the monitoring boreholes specified above and at the frequency specified in Schedule B.

Section 1.4.2

Section 5 Section 4.4

Section 4.4 Section 6.3.2

Section 6.3.2 and Table 4-1 Section 8

Section 4.3 Section 4.2 Section4.2 Section 5 Appendix D

Section 3 Section 5 Section 6 Table 4-1 Section 5 Section 7 Table 4-1 Section 8 Section 3.6, Section 6.3.2, Table 4-1 Section 3.7 Section 3.5 and 5 Section 7 Section 9.2 Section 1.4 and 9 Section 4

Section 4.2 Section 5

GSMCP – Karangahape Station

Consent Condition

Brief Condition Description 106 107 108

109

110

Building Inspection

111

112 113 114

115

116 117 119 Page 10

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These records, reported in reduced level, shall be compiled and submitted to the Manager at monthly intervals.

The groundwater alert trigger level criteria is listed in Schedule C for the monitoring boreholes.

Where groundwater alert trigger levels are exceeded, as identified from monitoring data obtained pursuant to Condition 105, the Consent Holder shall undertake the actions set out in the certified GSMCP. a. notify the Manager within 2 working days, advising the trigger exceedance, the risk of settlement causing damage to buildings, and details of the actions taken; and b. send a copy of the material notified to Council to the relevant building owner Prior to the commencement of dewatering/excavation, the Consent Holder shall employ an independent Senior Qualified Person to undertake a detailed pre-construction condition survey, of all relevant buildings to confirm their existing condition, subject to the approval of the property owner. The survey shall include, but not be limited to, the following: a. any information about the type of foundations; b. existing levels of damage considered to be of an aesthetic or superficial nature; c. existing levels of damage considered to affect the serviceability of the building where visually apparent and without recourse to intrusive or destructive investigation; d. a professional opinion as to whether observed damage may or may not be associated with actual structural damage; e. susceptibility of the building or structure to further movement; f. specific assessment of building damage with reference to the trigger levels identified in Appendix C of the Consent; g. review of proposed alarm and alert trigger levels to confirm they are appropriately set and movement less than trigger levels set will not exacerbate damage, and whether the monitoring frequency and locations of monitoring points are adequate; and h. photographic evidence of (b) and (c).

Where the Consent Holder is required to access property (including buildings or structures) owned by a third party to undertake monitoring, surveys or inspections and that access is declined or subject to what the Consent Holder considers to be unreasonable terms, the Consent Holder shall notify the Manager of that circumstance, and provide an alternative monitoring plan which includes the matters stated in Condition 100.

Any condition survey undertaken in accordance with Condition 109, or any other condition surveys undertaken by the Consent Holder, shall be undertaken as follows: a. The Senior Qualified Person shall be identified in the CEMP (required by Condition 36); b. Contact owners of those buildings and structures where a condition survey is to be undertaken to confirm the timing and methodology for undertaking a pre-construction condition survey; c. Record all contact, correspondence and communication with owners and this shall be available on request for the Council; d. Provide the building condition survey or structure condition survey report to the relevant property owner and the Council within 15 working days of the survey being undertaken; e. The Consent Holder shall undertake a visual inspection during construction if requested by the building or structure owner where a pre-construction condition survey has been undertaken and monitoring data and observations note any changes from the pre-construction condition survey report. f. Develop a system of monitoring the condition of existing buildings or structures which is commensurate with the type of the existing building or structure and the proximity of the project works in order to assess whether or not construction activities are compromising the structural integrity of the building or structure.

Should the pre-construction building condition survey and assessment highlight greater sensitivity of buildings than envisaged by the application, and should this increased sensitivity mean that the Serviceability Limit for the building may be exceeded, then the Consent Holder shall, at its cost, implement additional measures that may include modifications to the design of the retention systems or further geotechnical investigation).

The Consent Holder shall carry out a visual inspection of the surrounding ground and external building facades of the listed buildings in Appendix 2 adjacent to the tunnel/trench and station alignment to monitor for any deterioration or movement of any pre-existing cracks at a frequency to be specified in the GSMCP. Keep a record of the time, date and any observations for each inspection. This record is to be maintained and submitted to Auckland Council in accordance with Condition 128.

No earlier than six months after Completion of Dewatering and within six months of Completion of Construction, a detailed condition survey all previously surveyed buildings, structures and water, stormwater and wastewater services, shall be prepared by a suitably qualified engineering professional.

This condition survey report shall address all matters reviewed in the pre-dewatering condition survey. It shall also identify any new damage (if any) that has occurred since the predewatering condition survey was undertaken and include a determination of the cause of any such damage and steps to repair it as provided for in Condition 125.

The requirements of this condition need not be fulfilled for any particular building where the Consent Holder can provide written evidence to the Manager that the current owner of that building has advised they do not require such a condition survey.

At the reasonable request of the Manager, the Consent Holder shall, without delay, undertake an additional condition survey of any building within the area defined by the groundwater monitoring, deformation monitoring and modelling undertaken pursuant to the conditions of this consent potentially affected by excavation, for the purpose of checking for damage and follow up with a report of damage to that building.

Subject to Condition 125, the requirement for any such condition survey will cease 6 months after the Completion of Construction, unless the requirements of Condition 115 have not been met and subject to a consistent pattern of deformation records having been obtained in this period in which no evidence of adverse effects is apparent.

Establishment and maintenance of a settlement monitoring network (ground settlement and building movement monitoring marks) to detect any deformation: a. The minimum scope of settlement monitoring is shown on Appendix 1 of the Consent

Section Addressed in

Section 8

Section 6.2

Section 6.2

Section 6.2 Table 4-1

Section 8 Section 6.3 Table 4-1

GSMCP – Karangahape Station

Consent Condition

Ground Surface and Building Monitoring 120

124

Contingency

125

126 127 Reporting 128

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Brief Condition Description

Section Addressed in

b. Subject to the owners’ approval, at least two sets (minimum three pins) of building movement monitoring marks shall be located on each building listed in Appendix 2 of the Consent. c. The final location and number of building movement monitoring marks shall take into account the building type and size, accessibility to survey the marks and risk of damage from ground settlement, as determined by requirements of conditions of this consent, and the effects of differential settlement from the predicted settlement contours on the drawings in Appendix 1 as modified by the detailed design and reflected in the GSMCP.

Appendix D

The Consent Holder shall survey and record each ground and building movement mark in accordance with Schedule D in the Consent; and records of the baseline monitoring shall be compiled and submitted to the Manager prior to the Commencement of Dewatering.

In the event that monitoring of ground or building settlement, differential settlement, or horizontal movement associated with the construction works identifies movement which exceeds the vertical and horizontal movement triggers detailed in Appendix 2 or any revised trigger levels subject of this consent, then the Consent Holder shall instigate the Response Plan detailed in the GSMCP and undertake the following procedures: a. Notify Auckland Council and the IBA within 24 hours; b & c. If measurements exceed any of the alert values, then a Senior Qualified Person engaged by the Consent Holder or the Consent Holder’s contractor shall re- assess the works constructed up to that time to confirm that works’ progress against the design predictions are within expectations, whether additional measures (if any) are required to restrain further increases in movement and that possible ensuing effects will exceed Serviceability Limits. Measures (if any) to be implemented, identified in the Response Plan in the GSMCP or as agreed with the IBA, may include an increase in the frequency of monitoring, or additional support measures. The Senior Qualified Person shall prepare and submit a written report to Auckland Council, within one week of alert level exceedance, which provides analyses of all monitoring data relating to the exceedance of any of the trigger levels and any actions taken. d. If measurements exceed any of the alarm values the Consent Holder shall: i) Follow the process identified in Condition 124(b); ii) Commission and submit a written report, prepared by the Senior Qualified Person engaged in accordance with Condition 124(b) to the Manager, within one week of alarm level exceedance, which provides analyses of all monitoring data, relating to the exceedance of any of the trigger levels and any recommendations for remedial actions, if required, in order to avoid damage that will affect building Serviceability and which may also allow Completion of Construction; and iii) Implement the recommendations of the report. In the instance that the recommendation is to stop work, pursuant to Conditions 124(b) and (d)(ii), the remedial action(s) that have been recommended shall be undertaken before the works recommence. e. In relation to alarm level exceedance, the recommendations of the IBA (refer Condition 92), which may include remedial actions up to and including stopping the works, if that is (in the opinion of the IBA) in the best interests of preventing building serviceability damage, shall be implemented by the Consent Holder (unless the building owner(s) request in writing that the construction works are to be completed in accordance with the report prepared under Condition124 (d)(ii).

If any damage to buildings, structures or services is caused wholly or in part by the exercising of this consent, the Consent Holder shall: a. notify the Manager and the asset owner as soon as practical; b. engage a Senior Qualified Person to prepare a report as soon as practical, describing the damage and identifying methods to avoid and mitigate the potential for Serviceability damage and to remedy any damage caused wholly or in part by the exercising of this consent; and provide a copy of the report to the Manager and the asset owner; and c. thereafter promptly undertake (at the entire cost of the Consent Holder) all necessary repairs to fully remedy the damage caused by the exercise of this consent, with timing to be agreed with the asset owners. “Entire cost” includes all design and consenting costs as well as all construction costs.

This obligation as a condition of the resource consent shall apply to all Damage that is identified during the latest of the periods listed below: i) Two years after Completion of Dewatering; or ii) One year after groundwater levels have stabilised; and iii) The completion of post construction monitoring required to be carried out under Condition 121; and iv) Six months after any completion of any other works associated with the project which have the potential to cause settlement.

Auckland Council shall be advised in writing within ten working days of Completion of Dewatering.

Auckland Council shall be advised in writing within ten working days of Completion of Construction.

All data collected as required by conditions of this consent from Commencement of Dewatering to completion of monitoring are to be compiled, compared with the relevant trigger levels and submitted to the Manager at two monthly intervals, unless otherwise specified in this consent, setting out the previous results, providing an explanation for any trends and providing a construction progress timeline.

Section 8

Section 8

Section 4

GSMCP – Karangahape Station

1.7

Sustainability

The Link Alliance is seeking an Infrastructure Sustainability Council of Australia (ISCA) Infrastructure Sustainability (IS) Rating. Further details can be found in the CEMP and Sustainability Rating Management Plan. Project sustainability requirements that relate directly to this GSMCP are included in Appendix G. These requirements are imbedded within the GSMCP to ensure that sustainability is a key focus and ‘the way we do things’.

In some cases, the IS requirements and sustainability goals enhance the consent requirements.

Further detail on sustainability is provided in Section 1.7 of the CEMP.

1.8

GSMCP Review and updates

This GSMCP is a live document that will be reviewed at least annually, or as a result of a material change to the project, or to address unforeseen settlement effects arising from construction, or unresolved complaints. Any material changes to this GSMCP must be certified by Auckland Council prior to any on-site activity reliant upon the change commencing. Refer to the CEMP for further detail on the review and updating process

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GSMCP – Karangahape Station

2.

Project Description

2.1 Karangahape Station Early Works Early works will be undertaken at the new Karangahape Station site to enable and provide for the subsequent main construction works. The early works are detailed in the CEMP. An overview of the work is presented in the drawings included in Appendix A (CRL-KRD-CON-LKA-SKE-EW BER and CRLKRD-CON-LKA-SKE-EW MERCURY) and summarised in Table 2-1.

Table 2-1 Overview of Karangahape Early Works

Works location

Overview of construction activities

Beresford Square / Pitt Street

 Relocation of network utilities located within the footprint of the new Karangahape Station in Beresford Square / Pitt Street;  Removal of street trees and the demolition of the café / toilet in Beresford Square;  Establishment of the Beresford Square Construction Support Area to provide site offices, construction vehicle parking, laydown areas and storage of plant and equipment etc.;  Closure of Beresford Square to vehicle traffic (other than construction traffic) while retaining pedestrian and cycle access; and .  Removal of existing street furniture where required (such as seating, street lighting (to be replaced with temporary lighting).

Mercury Lane

 Relocation of network utilities located within the footprint of the new Karangahape Station in Mercury Lane; and  Establishment of the Mercury Lane Construction Support Area to provide site offices, construction vehicle parking, laydown areas and storage of plant and equipment etc.

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GSMCP – Karangahape Station

3.

Existing Environment

3.1 Land Use and Topography The new Karangahape Station will be located beneath the ridge lines of Karangahape Road and Pitt Street. Above the Station, topographic elevation ranges from approximately 60 to 65 m RL. Topography slopes radially away to lower elevations from the intersection of Karangahape Road and Pitt Street; northeast towards the head of Myers Park (43 m RL) and north through southeast towards the Central Motorway Junction (40 – 50 m RL).

The land uses surrounding the new Karangahape Station area are ‘mixed-use’, including small-scale light industrial activities, residential buildings, cafes, restaurants and community facilities.

3.2 Geology The majority of the Auckland urban area is underlain by sedimentary rocks of the East Coast Bays Formation (ECBF), terrestrial deposits and shallow marine sediments of the Tauranga Group and volcanic deposits of the Auckland Volcanic Field1. Throughout much of the Auckland CBD, man-made fill has been placed and overlies the natural geology described above.

Several stages of geotechnical investigations have been completed along the CRL alignment and during prior CRL project stages. The results from these were used to develop a 3-D Leapfrog® ground model for the CRL project area.

Based on the available geological information, the general vertical stratigraphic sequence in the area comprises the following: 

Fill, generally varying in thickness between 2 - 3 m along the Beresford Square and Mercury Lane construction areas, but increases up to 4 m thick just south of the ridge crest at Karangahape Road and 5 - 6 m thick towards the lower slopes and towards CMJ;



Local alluvium deposits of Pleistocene age Tauranga Group Alluvium infill the heads of paleotributary gullies south of the ridge crest;



The thickness of the weathered and residual ECBF varies in the area, possibly as a result of preferential weathering down steeply inclined joints or faults leading to deeper weathering profiles in areas. The residual ECBF underlies the fill (where no alluvium deposits are present), ranging from 4 - 8 m and 3 - 6 m along Beresford Square and Mercury Lane respectively. The thicknesses of the weathered ECBF vary similarly, before grading into unweathered ECBF at depths between 46 and 54 m RL;



The channelised sandstone unit in the Central Motorway Junction area is mapped throughout the Karangahape Station area. The base of the channelised sandstone unit approximates the vertical rail track alignment through this area. The unit is gently folded and faulted, with occasional swarms of joints which may be related to nearby faulting.

Cross-sections along the Beresford Square and Mercury Lane areas were exported from the 3-D model and are included in Appendix B to this GSCMP. 1

Kermode, L. O., (1992). Geology of the Auckland urban area. Scale 1:50 000. Institute of Geological & Nuclear Sciences Geological Map 2. Lower Hutt, New Zealand, Institute of Geological & Nuclear Sciences Ltd. 1 sheet + 63 p.

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GSMCP – Karangahape Station

3.3 Hydrogeology Perched Groundwater A review of the hydrogeological studies completed during prior CRL project stages and historic groundwater monitoring data from piezometers installed in the region of Beresford Square and Mercury Lane indicates the presence of a shallow or perched groundwater level, varying between approximately 2 m b GL (maximum high) to 6 m b GL (maximum low). The perched water level fluctuates between maximum and minimum levels in response to rainfall events, particularly in the Beresford Square area. These zones were assessed to be relatively isolated and laterally discontinuous. The topographical high position of this area and fact that the surrounding areas are largely covered by man-made surfaces means that any perched groundwater levels are likely to be predominantly recharged by leaking services and flowing to local topographic sinks or shallow drainage infrastructure.

The groundwater conditions within the upper soils are largely unaffected by underdrainage from within the regional groundwater tables that lie within the ECBF. Any potential long-term effects on the perched groundwater profile arising from de-pressurisation of the regional groundwater system is likely to be largely buffered by rainfall recharge2.

Regional Groundwater System Beneath the perched groundwater zone (at depths varying between approximately 8 to 10 m bGL), seasonally permanent saturation of the fill / alluvium / residual ECBF is assumed to occur, representing the top of the regional groundwater system in this area. This regional hydrogeological regime is relatively complex, with up to four regional groundwater levels conceptualised in the hydrogeological model of the area.

3.4 Existing Buildings and Structures A list of buildings in the area adjacent to the Karangahape Station early works is provided in Table 3-1 below.

Table 3-1 List of buildings – Karangahape Station early works

Beresford Square

Mercury Lane

22-28 Beresford Square 283 Karangahape Road (Samoa House) 16-18 Beresford Square 259-281 Karangahape Road 251-253 Karangahape Road (Koia Building) 61-65 Pitt Street

9 Mercury Lane (Mercury Theatre) 238 Karangahape Road (George Court Building) 1 Cross Street (George Court Factory Building)

3.5 Existing Basements Buildings with existing basements in the area of the early works are as follows: 

224-244 Karangahape Road (George Court Building), which includes two basement levels with the bottom one only on the Southern end of the building.

2

PDP, (2015). Auckland City Rail Link Project Karangahape Road Pumping Test Report (Stage 3). Prepared for Auckland Transport, dated May 2015.

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GSMCP – Karangahape Station 

1 Cross Street (George Court Factory Building), which includes 1 basement level.

3.6 Existing Utilities Several network utilities have been identified within the area of the Karangahape Station early works including stormwater, wastewater, electricity, telecommunications and gas. These include: Beresford Square 

22kV oil filled cables running from Day Street, along the north side of Beresford Square, north up Pitt Street.



Low voltage electricity cables, running south-east along the southern side of Beresford Square.



Stormwater and wastewater lines which run south-east near the centre of Beresford Square.



Potable water lines which run along both sides of Beresford Square.



Telecommunication cables, running along both sides of Beresford Square.



Gas running along the southern side of Beresford Square.

Mercury Lane 

Low voltage and high voltage electricity cables, running south along the eastern side of Mercury Lane.



Telecommunication cables, running south along both sides of Mercury Lane.



Gas runs along the western side of Mercury Lane.



Stormwater, wastewater and potable water lines run along the centre of Mercury Lane.

3.7 Issued Groundwater Diversion Consents Only one granted groundwater diversion consent currently lodged with Auckland Council, is near or within the vicinity of the Karanagahape Station early works. This consent relates to 26 Poynton Terrace (Consent No. 43162), located approximately 120 m to the east of the Beresford Square entrance.

Condition 100 (i) of the Consent requires the GSMCP to include details of the monitoring proposed to be undertaken to protect the issued groundwater diversion consents listed in the Consent against cumulative settlement effects. This consent will not be affected by the Karangahape Station early works but will be reviewed during the preparation of the GSMCP for the main station works.

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GSMCP – Karangahape Station

4.

Overview of Monitoring and Reporting Requirements

This section provides an overview of the monitoring and reporting required for the Karangahape Station early works in accordance with the consent conditions.

4.1 Monitoring and Reporting Requirements Monitoring shall be completed and records compiled and submitted to Auckland Council by those responsible during the stages and frequencies outlined in Figure 4-1 and Table 4-1 hereafter.

Pre-construction Monitoring

•This monitoring phase will provide baseline data against which effects resulting from the construction works can be assessed. The outcomes will form part of the input for the construction phase assessments.

During Construction Monitoring

•Monitoring during the bulk excavation phase will be used to verify the design analyses, by comparing the actual measurements with those estimated. The monitoring data will be used to reassess the building damage classifications at critical locations.

•If these reassessments indicate that the damage classifications have increased significantly then additional analyses, increased monitoring or other actions may be required. Mitigation options, discussed in Section 8 of this GSMCP, may also be required to be implemented.

Post-Construction Monitoring

•Where specified in the Consent, monitoring will occur until the various stages of works are completed (excavation, dewatering and construction), and shall continue as required until stable measurements are demonstrated, and written approval is provided

by AC.

Figure 4-1 Summary of Construction Monitoring Stages

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GSMCP – Karangahape Station Table 4-1: Summary of Monitoring Requirements

Monitoring Type

Construction Stage

Minimum Measurement Frequency

Baseline

Weekly for at least 3 months before commencing dewatering and those boreholes listed in Appendix 3 of the Consent.

Measureme nt Accuracy

Three times a week for all monitoring boreholes until completion of dewatering.

Groundwater Monitoring

Excavation/ dewatering

PostConstruction Dewatering

Monitoring shall continue until either six months after the completion of dewatering, or until such time following the completion of dewatering that monitoring of settlement and building monitoring marks has ceased under Condition 120.

Baseline

A detailed pre-construction condition survey is to be carried out of all buildings identified in Appendix 2 of the Consent and relevant to this GSMCP (subject to approval of the property owner).

Excavation/ dewatering

A visual inspection will be undertaken during construction if requested by the building or structure owner where a pre-construction condition survey has been undertaken and visual observations or monitoring data indicates changes from the pre-construction condition.

Building Condition Surveys (BCS)

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Daily, should the Groundwater Alert Trigger level be exceeded.

| Early Works - Rev 1

Reporting Requirement to Auckland Council, unless otherwise stated

Related Consent Conditions

Relevant GSMCP Sections

104 – 108

Section 5

109 - 117

Section 6.2

Monthly for routine monitoring.

10mm

Within 2 working days of any alert trigger level exceedances.

Within 15 working days to the relevant property owner and Auckland Council.

N/A

A record is to be maintained of the time, date and any observations for each inspection. This record is to be maintained and

GSMCP – Karangahape Station

Monitoring Type

Construction Stage

Minimum Measurement Frequency

Measureme nt Accuracy

Visual inspections of the surrounding ground and external facades of buildings identified in Section 6.2 will be carried out quarterly (3 months) from the commencement of excavation / dewatering, or within one week of the completion of works for shorter duration activities. This is to monitor any deterioration or further cracking from pre-construction conditions.

PostConstruction Dewatering/ excavation

A post-construction condition survey shall be carried out no earlier than 6 months after completion of dewatering/excavation and within 6 months of completion of construction for any building that had a pre-construction survey.

Baseline

Each ground settlement and building movement monitoring mark shall be surveyed and recorded at least three times prior to the commencement of excavation / dewatering to establish a baseline elevation.

Ground Surface and Building Monitoring

Depending on the stage of construction:

Excavation/ dewatering

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-

Monthly, at each ground settlement and building monitoring mark,

-

Daily for two weeks and weekly thereafter for all ground and building settlement markers within 50m of excavations during excavation until such time following the completion of

Horizontal and vertical accuracy of at least Âą2 mm, or as otherwise achieved by precise levelling during baseline phase.

Reporting Requirement to Auckland Council, unless otherwise stated submitted to AC at two monthly intervals or upon reasonable request from the AC Representative.

Related Consent Conditions

Relevant GSMCP Sections

To be compiled and submitted to AC prior to the commencement of excavation.

A record is to be maintained of the time, date and any observations for each survey, and submitted to the Council at two monthly intervals.

119 - 120

Section 6.3

GSMCP – Karangahape Station

Monitoring Type

Construction Stage

Minimum Measurement Frequency

excavation that stable measurements are demonstrated.

PostConstruction Dewatering/ excavation

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Monthly for six months, or until stable measurements are demonstrated and written approval is provided by Council for certification.

Measureme nt Accuracy

Reporting Requirement to Auckland Council, unless otherwise stated

Related Consent Conditions

Relevant GSMCP Sections

GSMCP – Karangahape Station

4.2 Notification and GSMCP Certification The Link Alliance will advise Auckland Council in writing of the date of the proposed commencement of dewatering. As defined in the Consent, this shall mean the commencement of bulk excavation and / or the commencement of the taking or diversion of groundwater, other than for initial state monitoring purposes.

The GSMCP shall be prepared and submitted by the Consent Holder (CRLL) to the Manager (AC) for certification at least 20 working days prior to the Commencement of Dewatering, together with a statement from the IBA confirming its adequacy. Dewatering / excavation on the site will not commence until certification from AC is provided.

CRLL shall request Council’s (The Manager) determination as to whether the GSMCP can be certified, in writing within 10 working days of receipt of the GSMCP. CRLL shall also advise the Manager in writing within ten working days of Completion of Dewatering and Construction.

4.3 Data Collection and Reporting Requirements All data collected will be compiled, compared with the relevant trigger levels (summarised in Section 7) and submitted to Auckland Council at two monthly intervals, unless otherwise specified or requested in the Consent.

4.4 Independent Building Assessor Reporting Requirements The Consent Holder shall request that Council engage, at the cost of the Consent Holder, a suitably qualified independent specialist, agreed to by the Consent Holder, to fill the role of Independent Building Assessor (IBA) The IBA shall report to Auckland Council on building damage matters, and how these matters may be addressed, with regards to the following: 

Site-specific assessments are undertaken to an appropriate level of detail;



Monitoring data is collected, interpreted and assessed in regard to limiting effects to avoid Serviceability Damage;



Alert and Alarm limits; and



Any matters with the required BCS, visual inspections, and trigger level exceedance reports in accordance with the response and repairs.

4.5 Roles and Responsibilities The roles and responsibilities relevant to the implementation of this GSMCP are outlined in Table 4-2 (refer also to the CEMP for additional detail on the wider project team roles and responsibilities).

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GSMCP – Karangahape Station Table 4-2 Roles and responsibilities

Role

Role Responsibility

Instrumentation and Monitoring Manager

Reviewing the data and correlating the monitoring observations with construction activities and design assumptions.

Communicating trends and observations to the Construction Manager, relevant members of the construction team, and CRLL. Responding to Alert and Alarm triggers.

Managing contingency measures and responses in the event that an Alarm level is exceeded.

Design Lead – Groundwater and Settlement Effects

Prepare, review and update of GSMCP

Independent Building Assessor (IBA)

Review the GSMCP and any reports associated with alarm triggers.

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Additional inputs will be provided on an as-requested basis, with assistance from other Technical Specialists as required.

As an advocate for local stakeholders, the IBA will also receive and review monitoring data and on behalf of AC to track progress and building damage and building effects.

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GSMCP – Karangahape Station

5.

Groundwater Monitoring Plan

This section of the GSMCP presents the methodology for the monitoring of groundwater levels as part of the overall Assessment of Settlement Effects during the Project.

5.1 Early Works The proposed early works will extend to a maximum depth of 5 m bGL and will not intersect the regional groundwater regime.

To assess the likely impact of the proposed early works on any zones of shallower perched groundwater in the Karangahape Station area, the following was considered: 

The early works (and any associated dewatering) will be of a temporary nature and the maximum dewatering period will be approximately four weeks;



Drawdown will be slow within the relatively low hydraulic conductivity fill / Tauranga Group / residual ECBF materials, and the excavations shored from the top down. The maximum radius of influence (i.e. extent of drawdown) from the edge of the excavation will be localised;



Deeper excavations will be supported to ensure the stability of the works, reducing any potential inflow;



The proposed early works will involve the relocation of existing stormwater and wastewater utilities in the area. These are installed at depths ranging between 2.5 and 4.5 m bGL, and were installed / replaced at various stages in the past. Although no information is available to confirm, it is likely that these services would have been placed on a granular fill bedding material and have impacted any shallow groundwater levels; and



The perched water tables are not laterally continuous and would have already been extensively modified from its natural condition by the surrounding building development, filling and existing utilities acting as drains and connections between lenses.

Any impact on perched groundwater levels from the early works is likely to be highly localised (i.e. in the area immediately surrounding the early works excavation), and any settlement effects due to dewatering are likely to be negligible. No groundwater monitoring plan is included as part of this GSMCP for the Karangahape Station early works.

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GSMCP – Karangahape Station

6.

Settlement Monitoring Plan

6.1 Introduction The settlement monitoring actions, instrumentation and trigger levels described in this section are based on the outcome of the assessment of wall deflection limits for the early works construction stage (attached as Appendix E to this document), and in accordance with the relevant conditions of the Consent.

This section outlines the building condition and settlement monitoring program Link Alliance will implement to: 

Verify design assumptions;



Confirm the construction induced surface settlements; and



Provide warning that mitigation is required to minimise or rectify potential adverse effects of settlement on structures.

The schedule of monitoring actions is summarised in Appendix D.

6.2 Building Condition Surveys The buildings for which BCS are required as part of the Karangahape Station early works are summarised in Table 6-1 (inclusive of those structures listed in Appendix 2 of the Consent): Table 6-1 Building Condition Surveys - Karangahape Station Early Works

Building ID No. (Consent)

Address Street No.

Street

47

16-18

Beresford Square

48

259-281

Karangahape Road

49

251-253

Karangahape Road

50

61-65

54

238

60

9

Mercury Lane

65

1

Cross Street

157

22-28

Beresford Square

158

283

Karangahape Road

Pitt Street Karangahape Road

The BCS will be completed prior to the early works to identify and monitor effects to buildings in accordance with consent Conditions 109 - 117.

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GSMCP – Karangahape Station The following general requirements apply to all BCS and visual inspections undertaken during the works: 

The BCS shall be undertaken by an independent Senior Qualified Person.



All contact, correspondence and communication with building owners will be recorded, with documents available on request.



The BCS or structure condition survey reports shall be provided by the Link Alliance to the relevant property owner within 15 working days of any survey being undertaken. A copy of each report shall also be provided to CRLL and Auckland Council.



Damage to buildings identified during BCS and visual inspections resulting from the early works activities requires action as outlined in Section 8 of this GSMCP.

6.2.1. Pre-Construction Building Condition Surveys Individual pre-construction BCS of all structures listed in Section 6.2 of this GSMCP will be undertaken to establish a baseline building condition against which any subsequent surveys can be compared. The owners of the buildings and structures will be contacted in advance to confirm the timing and methodology for the pre-construction survey. All contact, correspondence and communication with the owners will be recorded and available on request for Auckland Council.

Should the pre-construction building condition survey and assessment highlight greater sensitivity of buildings than envisaged by the application, and should this increased sensitivity mean that the Serviceability Limit for the building may be exceeded, then the Link Alliance shall, implement additional measures as discussed in Section 8.

In the event that access is declined or subject to what the Consent Holder considers to be

unreasonable terms, the Consent Holder shall notify the Manager of that circumstance, and provide an alternative monitoring plan which includes the matters stated in Condition 100 of the Consent.

6.2.2. During-Construction Building Condition Surveys Visual inspection of ground and buildings adjacent to the early works shall be carried out according to consent conditions as follows: 

The Link Alliance will undertake a visual inspection during construction if requested by the building or structure owner where a pre-construction condition survey has been undertaken and monitoring data and observations note any changes from the pre-construction condition survey report; and



The Link Alliance will carry out a visual inspection of the surrounding ground and external building facades of the buildings identified in Section 6.2 to monitor any deterioration or further cracking of any pre-existing cracks. This will be carried out at least quarterly from the commencement of any dewatering / excavation until completion of the excavation, or (in the event of shorter duration activities) within 1 week of completion of the works.

A record will be maintained of the time, date and any observations for each inspection. This record will be maintained and submitted to Auckland Council.

6.2.3. Post-Construction Building Condition Surveys

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GSMCP – Karangahape Station Post-construction BCS will be completed after the completion of the Karangahape Station main works (which will follow the early works outlined in this GSMCP). No earlier than 6 months after the completion of the Karangahape Station main works dewatering / excavation, and within 6 months of completion of the Karangahape Station main works construction, post-construction BCS will be carried out on all buildings where a building condition survey was undertaken prior and during the construction phase. The survey report will include an assessment of the cause of any damage identified. If a complaint is made around building damage following completion of the early works, a post-early works construction BCS will be carried out for that particular building.

Additional BCS and reporting up to 6 months’ post-construction on any building within the area potentially affected by the excavation may be completed at the request of Auckland Council. The requirements for any such survey will cease six months after the completion of construction, and subject to a consistent pattern of deformation records in which no evidence of adverse effects is apparent.

The post-construction building surveys may not be required in the event that the building owner agrees that the building survey is not required, and written evidence is provided to Auckland Council.

6.3 Monitoring 6.3.1. Ground and Buildings Ground and building survey monitoring marks will be installed along the areas likely to be affected by the early works, and as shown in the drawings attached as Appendix D. The locations and spacing of these positions have been selected to avoid future (main works) duplication of monitoring points.

Where the effects from the utility relocation works are likely to extend beyond the monitoring area proposed for the main works, the proposed monitoring points have been extended to include the area of utility works. 



Building Monitoring Marks: A minimum of two sets of three pins, will be installed at three different levels along the building face and on each building identified and listed in Section 3.4 of this GSMCP addendum. Monitoring marks are proposed to be installed at 10m centreto-centre intervals, with at least one set installed on the side of the structure closest to the excavation.

Ground Monitoring Marks: Monitoring marks will be installed at 5m centre-to-centre spacing along the first 10m of the building perimeter walls that lead away from the edge of the excavation, increasing to 5m spacing after that. At least one monitoring point is required at the rear of the building footprint. The spacing of ground monitoring points can be reduced to 10m spacing past the building footprint and up to the 5mm settlement contour line developed for the main works in this area.

The location and number of monitoring marks takes into account the building type/size, accessibility and risk of damage from ground settlement.

Building Movement Monitoring Markers shall be located on each building identified subject to owners’ approval. This will allow the actual building movement to be monitored and compared with the estimated potential effects. It is proposed, and subject to owners’ approval, that these monitoring points be left in place after the required monitoring period for the early works has ended and in anticipation of the main works.

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GSMCP – Karangahape Station Monitoring will be required before construction commences, during construction and following completion to confirm the effects of the early works (as summarised in Table 4-1).

Pre-construction The Link Alliance will survey and record each ground settlement and building movement monitoring mark at least three times prior to the commencement of excavation to establish a baseline set of readings. Monitoring data from C2 indicate seasonal shrink-swell movements in the order of up to +5mm to -5mm (measured from an average level over a 12-month monitoring cycle) could be expected. The recorded baseline monitoring readings will take into account this historic data trends, and the effects considered in the adopted trigger levels for the construction/post-construction monitoring periods.

All settlement and building monitoring mark surveys will be to a horizontal and vertical accuracy of at least ± 2mm as achieved by precise levelling. These records will be compiled and submitted to Auckland Council prior to the commencement of excavation.

During Construction Settlement Monitoring Monitoring during construction will comprise surveys of monitoring marks. The ongoing frequency monitoring of the survey marks will vary depending on the monitoring stations position relative to the early works excavation. 

At each ground settlement and building monitoring mark, within 50 m of an excavation during excavation / dewatering on a daily basis for two weeks and weekly thereafter; and



At all other ground settlement and building monitoring mark locations on a monthly basis.

Post-Construction Settlement Monitoring Monitoring of the survey marks will continue monthly for six months, or until stable measurements are demonstrated and written approval is provided by Council for certification.

6.3.2. Utilities and Infrastructure Pre-construction The Link Alliance has identified the utilities potentially affected by the early works and have consulted with the relevant utility owners to determine the extent of pre-construction surveys required.

CCTV surveys will be completed on the existing stormwater and wastewater networks in the areas adjacent to the early works excavations. No need for other pre-construction surveys was identified, as the early works activities are primarily concerned with relocating the utilities in question..

During Construction Settlement Monitoring The monitoring of any settlement effects on adjacent utilities will be carried out utilising the ground settlement markers utilised for ground settlement monitoring as outlined in Section 6.3.1.

Post-Construction Settlement Monitoring A post-construction condition survey will be carried out no earlier than 6 months after completion of dewatering/excavation of the Karangahape Station main works, and within 6 months of completion of construction for any building that had a pre-construction survey. This will serve to confirm that the immediately adjacent utilities identified in the pre-construction survey have not been damaged.

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GSMCP – Karangahape Station The post-completion survey is to be provided in writing to Auckland Council and will include a determination of the cause of damage identified (if any) since the pre-construction survey, and a description of the steps taken to repair any damage.

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GSMCP – Karangahape Station

7.

Settlement Trigger Levels

The trigger levels for the respective monitoring actions outlined above are presented in Table C-1 and C-2, Appendix C. No excavation support design or construction methodology for the early works are currently available at the time of writing. This precludes any meaningful assessment of the ground surface settlement likely to be induced by the early works.

The trigger levels set out in the Consent (drawing CRL-SYW-RME-000-DRG-2640 Rev 4. dated 14 October 2016) have therefore been adopted for the respective buildings adjacent to the early works.

These, together with the expected effects from the main works, were used to estimate the tolerable amount of lateral deflection the shaft or trench excavation support could undergo without the resulting future cumulative settlement effects exceeding the trigger levels set out in the Consent.

Where the early works may influence buildings not included in the list of provisional trigger levels, tolerable deflections will be assessed on the basis that any subsequent settlement effects does not exceed the “negligible” damage category.

The proposed monitoring frequencies, alert and alarm trigger levels will be reviewed following the BCS and monitoring results from the early works to confirm they are appropriately set for the main works (refer to Section 9 for conditions of review of this GSMCP).

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8.

Response, Mitigation and Contingency Plan

8.1 Introduction This section presents the triggered action response plan required where exceedances of trigger levels have been identified during monitoring, as outlined in Sections 5 and 6 of this GSMCP.

8.2 Response to Alerts 8.2.1. Groundwater Alerts No groundwater alerts have been specified in this GSMCP for the Karangahape Station early works, for the reasons set out in Section 5.

8.2.2. Settlement Alerts In the event that settlement exceeds the identified Alert trigger levels during the early works, the following procedures will be undertaken: 

Auckland Council and the IBA will be notified within 24 hours;



A Senior Qualified Person within the Link Alliance shall re-assess the works constructed up to that time to confirm the works progress against design predictions, any additional measures to restrain further increases in movement, the possible ensuing effects will exceed serviceability limits; and



A written report will be prepared by the Senior Qualified Person responsible for overview of the monitoring, and provided to Auckland Council within one week of alert level exceedance. The report will provide analyses of all monitoring data relating to the exceedance of any of the trigger levels and any actions taken.

8.3 Response to Alarms In the event that settlement exceeds the identified Alarm trigger levels during construction works, the following procedures will be undertaken: 

Follow the process set out in Section 8.2;



Commission and submit a written report, prepared by the Senior Qualified Person engaged by the Link Alliance to the Manager, within one week of alarm level exceedance. This will provide analyses of all monitoring data, relating to the exceedance of any of the trigger levels and any recommendations for remedial actions, if required, in order to avoid damage that will affect building Serviceability, and which may also allow Completion of Construction; and



Implement the recommendations.

The IBA may also recommend actions to prevent damage to building serviceability, which may include stopping the works if that is in the best interests of preventing building serviceability damage. These recommended actions will be implemented, unless the building owner(s) request in writing that the construction works are to be completed in accordance with the report prepared by the Senior Qualified Person.

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GSMCP – Karangahape Station

8.4 Response to Building or Utility Damage In the event that damage to buildings, structures and / or services is reported during the early works or determined from a building condition survey or inspection the following will occur: 

The Link Alliance will notify the Manager and building / asset owner as soon as practically possible;



Engage a Senior Qualified Person to prepare a report as soon as practical, describing the damage and identifying methods to avoid and mitigate the potential for Serviceability damage and to remedy any damage caused wholly or in part by the exercising of this consent; and provide a copy of the report to the IBA, Manager and the building / asset owner;



The reported damage will be compared with the pre-construction building condition survey to determine if the damage is: 

Pre-existing,



New, or



Pre-existing, but exacerbated.



The construction history in the vicinity of the building will be reviewed, along with the recorded settlement history, to determine if the damage can be reasonably attributed to the construction works; and



If the damage can be reasonably attributed to the early works, repairs will be undertaken as soon as practicable unless written approval for this damage is provided from the owners stating alternative arrangements (in accordance with Consent condition 125). The timing and nature of the repairs will depend on the owner’s requirements, stage of construction and degree of damage.



This obligation as a condition of the Resource Consent shall apply to all Damage that is identified during the latest of the periods listed below:    

Two years after Completion of Dewatering; or One year after groundwater levels have stabilised; and The completion of post construction monitoring required to be carried out under Condition 121; and Six months after any completion of any other works associated with the project which have the potential to cause settlement.

8.5 Mitigation of Effects In the event that differential settlement or total settlement exceeds the identified Alert or Alarm trigger level during construction works, or ground conditions differ significantly from the design assumptions then the mitigation options include:

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

Additional specific structural and geotechnical evaluations;



Strengthen and / or stiffen ground support;



Installation of additional instrumentation; or | Karangahape Station Early Works

GSMCP – Karangahape Station 

Further structural assessment of an affected building.

The most appropriate contingency measure will be implemented to mitigate the actual or anticipated adverse effects of the triggering event.

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GSMCP – Karangahape Station

9.

Monitoring and Contingency Plan Review

This section outlines how the GSMCP will be reviewed including the mitigation and contingency procedures to make sure they are still applicable to the activities carried out.

9.1 General Review of the GSMCP The GSMCP will be updated, with the necessary certification by Auckland Council, throughout the course of the works to reflect material changes associated with changes to construction methods or site conditions. Auckland Council certification will be required for any relevant revisions of a material nature to the GSMCP. This GSMCP only addresses the proposed Karangahape Station early works construction stage activities. A separate GSMCP will be prepared for the Karangahape Station main construction works.

A yearly management review will be undertaken of the CEMP, including the GSMCP and other subplans. The management review procedure is described in further detail within the CEMP.

9.2 Review of Monitoring and Contingency Requirements The Consent allows for variation to the monitoring and reporting requirements, and performance standards (subject to certification by Auckland Council) in order to take account of information, including the results of previous monitoring and changed environmental knowledge, on:    

Ground conditions; Aquifer parameters; Groundwater levels; and Ground surface deformation.

Furthermore, the conditions of Consent allow for specific review and updates to the following: 



Review of the settlement alarm / alert / stop trigger levels: The trigger levels as provided in the Consent and adopted by this GSMCP may be revised following the completion of the BCS, and an assessment to confirm these are appropriately set and monitoring frequency is adequate.

Instrumentation: The specification of instruments, location and numbers of instruments may be modified as a result of the following:     



Page 33

Additional geotechnical investigation and ground characterisation; Specification of instruments and monitoring tools; Findings of the BCS; Detailed design of the temporary trench support system; Modelling of the anticipated ground movement and associated settlements adjacent to the planned excavation.

Response: The response plan included in the GSMCP (Section 8) will be implemented in the event that trigger levels are exceeded. The response plan may be updated in order to deal with any adverse effect on the environment arising or potentially arising from the exercise of this consent, and in particular effects on buildings, structures and services. | Karangahape Station Early Works

GSMCP – Karangahape Station

APPENDIX A: Drawings

Page 34

| Karangahape Station Early Works

N

ISO A1 594mm x 841mm

KEY PLAN

50

61-65

KARANGAHAPE STATION EARLY WORKS LIST OF BUILDINGS IDENTIFIED FOR CONDITION SURVEYS

ADDRESS STREET NO.

STREET

47 48 49 50 157 158

16-18 259-281 251-253 61-65 22-28 283

BERESFORD SQUARE KARANGAHAPE ROAD KARANGAHAPE ROAD PITT STREET BERESFORD SQUARE KARANGAHAPE ROAD

251-253

49

CONSENT ID NO.

48

259-281

8

283

15

Last saved by: HEINTJE OSHA(2019-09-16) Last Plotted: 2019-09-17 Filename: AECOM_AU_w\60560778\CRL-KRD-CON-LKA-SKE-EW_BERESFORD R0.DWG

47

16-18

15 7

22-28

CLIENT:

PROJECT MANAGEMENT INITIALS

BUILDING CONDITION SURVEY

JL DESIGNER

GB CHECKED

ISSUE/REVISION

SHEET TITLE

APPROVED

INCLUDED IN APPENDICES 1 & 2 OF THE CONSENT

KARANGAHAPE STATION INDICATIVE EARLY WORKS BERESFORD SQUARE BUILDING CONDITION SURVEYS

LINK ALLIANCE SUPPLEMENTARY BUILDINGS COMPANY NUMBER : 6267870

CREATOR ID :

PROJECT NAME

C3 - RRFP - STATIONS & TUNNELS

GT

I/R

DATE

DESCRIPTION

SHEET NUMBER

FIGURE A1

ISO A1 594mm x 841mm

KEY PLAN

238

54

N

1

65 PITT ST

KARANGAHAPE STATION EARLY WORKS LIST OF BUILDINGS IDENTIFIED FOR CONDITION SURVEYS

60

CONSENT ID NO.

ADDRESS STREET NO.

STREET

54 60

238 9

KARANGAHAPE ROAD MERCURY LANE

65

1

CROSS STREET

Last saved by: HEINTJE OSHA(2019-09-16) Last Plotted: 2019-09-17 Filename: AECOM_AU_w\60560778\CRL-KRD-CON-LKA-SKE-EW_BERESFORD R0.DWG

9

CLIENT:

PROJECT MANAGEMENT INITIALS

BUILDING CONDITION SURVEY

JL DESIGNER

GB CHECKED

ISSUE/REVISION

SHEET TITLE

APPROVED

INCLUDED IN APPENDICES 1 & 2 OF THE CONSENT

KARANGAHAPE STATION INDICATIVE EARLY WORKS MERCURY LANE BUILDING CONDITION SURVEYS

LINK ALLIANCE SUPPLEMENTARY BUILDINGS COMPANY NUMBER : 6267870

CREATOR ID :

PROJECT NAME

C3 - RRFP - STATIONS & TUNNELS

GT

I/R

DATE

DESCRIPTION

SHEET NUMBER

FIGURE A2

GSMCP – Karangahape Station

APPENDIX B: Geological Cross Sections

Page 35

| Karangahape Station Early Works

A

B

EBS1065-BH3 23m

7 14

4 5 6

24

6

34

6

50

60mRL

28

19

136

49

300

55 600

500

1500

429

50mRL

70mRL CRL3B-BH325 CRL2-BH216 6m 6m

1

60mRL

CRL1B-BH134 12m

70mRL

CRL2-BH218 CRL3B-BH314A 10m 7m CRL3B-BH314 7m

CRL2-BH275 14m CRL3B-BH275R 16m

CRL-KAR-XSec-BeresfordSquare1

9 13 18 41 41 94

300

88

429

150

50

40mRL

50mRL

29

429

40mRL

1000

30mRL

30mRL

20mRL

20mRL

10mRL

10mRL

0m

20m

40m

60m

80m

100m

120m

140m

160m

180m

Legend CRL-SYW-GEO-LKA-MOD-030200-B .: ER

LINK: F

.: EU

.: MBL

.: EW

.: MBU

LOOKING SOUTHWEST

Lines

NOTES: 1. THE GEOTECHNICAL INTERPRETATION OF GROUND CONDITIONS AT THIS SITE IS BASED ON OBSERVATIONS AND THE RESULTS OF TESTING AT DISCRETE LOCATIONS, AND THE CONTINUITY OF GROUND COULD VARY FROM THOSE PRESENTED ON THE DRAWING. 2. THIS INFORMATION CANNOT BE USED FOR THE PURPOSES OF PROCUREMENT OR CONSTRUCTION ACTIVITIES. 3. GEOLOGICAL MODEL DISPLAYED IS CRL-SYW-GEO-LKA-MOD-030200-B

20190628 - Track Alignment

Location A: 399544, 802485

Creator

Legal owner

Document type

Document status

Title

Identification number

KRD

B: 399392, 802582 Scale: 1:500

CRLL

Vertical exaggeration: 1x 0m

Responsible dept. Technical reference

50m

N. Kirkeby SECTION

CRL-KAR-XSecBeresfordSquare1

Approved by

DRAFT

Rev. Date of issue

1.0 17/07/2019

Sheet

1

A

B

6

2

8

2

25

12 18

2

55

25

4 13

50mRL

300

300

63

14

6 8

25

12

50

429

471

2 50

31

8

68

257

14 42 91

19 176

333

263

33 333 50 136

350

130

267

50mRL

250

405

1350

40mRL

60mRL

3

8

68

CRL5-BH511 29m CRL2-BH221 15m

5

CRL3B-EB312 0m

4

CRL2-BH278 9m

6

CRL5-BH510 2m

CRL4-CPT468 CRL4-BH451 20m 15m

CRL2-BH277 5m

10

60mRL

70mRL CRL4-CPT469 4m

CRL3B-BH320 2m

CRL1A-MB3A 4m

70mRL

CRL1A-MB3B 4m

CRL-KAR-XSec-MercuryLane

40mRL

600 429

30mRL

30mRL

20mRL

20mRL

10mRL

10mRL

0m

20m

40m

60m

80m

100m

120m

140m

160m

180m

Legend CRL-SYW-GEO-LKA-MOD-030200-B .: ER

.: TA

.: EU

LINK: F

.: EW

.: MBL

.: MBU LOOKING EAST

Lines

NOTES: 1. THE GEOTECHNICAL INTERPRETATION OF GROUND CONDITIONS AT THIS SITE IS BASED ON OBSERVATIONS AND THE RESULTS OF TESTING AT DISCRETE LOCATIONS, AND THE CONTINUITY OF GROUND COULD VARY FROM THOSE PRESENTED ON THE DRAWING. 2. THIS INFORMATION CANNOT BE USED FOR THE PURPOSES OF PROCUREMENT OR CONSTRUCTION ACTIVITIES. 3. GEOLOGICAL MODEL DISPLAYED IS CRL-SYW-GEO-LKA-MOD-030200-B

20190628 - Track Alignment

Location A: 399542, 802445

Creator

Legal owner

Document type

Document status

Title

Identification number

KRD

B: 399549, 802266 Scale: 1:500

CRLL

Vertical exaggeration: 1x 0m

Responsible dept. Technical reference

50m

N. Kirkeby

Approved by

SECTION

CRL-KAR-XSec-MercuryLane

DRAFT

Rev. Date of issue

1.0 17/07/2019

Sheet

1

GSMCP – Karangahape Station

APPENDIX C: Settlement Trigger Levels

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| Karangahape Station Early Works

Table C-1 Buildings - Alert/Alarm Trigger Levels Outlined in Resource Consent

Resource Consent (Appendix 2 of RC Conditions) ID No.

No.

Street

48

259-281 Karangahape Road

49 50 54 60

251-253 Karangahape Road 61-65 Pitt Street 238 Karangahape Road 9 Mercury Lane

63

20

East Street

64 65

23-31 1

Mercury Lane Cross Street

Alternative address 8-10 Beresford Square 12-14 Beresford Square 14-16 Beresford Square 2 Mercury Lane 17 Mercury Lane 21 Mercury Lane -

Vertical Movement (mm)

Differential Vertical Slope Across Building

Alert

Alarm

Alert

Alarm

8

10

1/1000

1/800

9 9 10 22

11 11 12 27

1/1000 1/1000 1/1000 1/795

1/800 1/800 1/800 1/636

To be demolished for project 14

18

1/1000

1/800

Table C-2 Buildings – No Alert/Alarm Trigger Levels Outlined in Resource Consent

ID No.

No.

47

16-18

157

22-28

158

283

Street Beresford Square Beresford Square Karangahape Road

Alternative address

Vertical Movement (mm)

Differential Vertical Slope Across Building

Alert

Alarm

Alert

Alarm

-

4

5

1/1000

1/800

-

4

5

1/1000

1/800

-

4

5

1/1000

1/800

GSMCP – Karangahape Station

APPENDIX D: Settlement Monitoring Instrumentation

Page 37

| Karangahape Station Early Works

ISO A1 594mm x 841mm

20A-20B

LEGEND

LEGEND NOTES

PROPOSED BUILDING SURVEY MONITORING

1.

PROPOSED SETTLEMENT SURVEY MONITORING

2.

3.

PROPOSED RETAINING WALL DEFLECTION SURVEY MONITORING

174

SOME INFORMATION SHOWNBUILDING ON THIS DRAWING HAS BEEN SOURCED FROM THIRD PROPOSED SURVEY MONITORING PARTIES. CO-ORDINATES ARE IN MT EDEN 2000 AND LEVELS ARE TO AUCKLAND L&S 1946 DATUM. PROPOSED SETTLEMENT SURVEY MONITORING LOCATION OF EXISTING14SERVICES HAVE BEEN EXTRACTED FROM AUCKLAND COUNCIL GIS AND UTILITIES PLANS AND ARE INDICATIVE. PHYSICAL LOCATION OF AFFECTED SERVICES WILL BE REQUIRED PRIOR TO CONSTRUCTION. ALL AFFECTED SERVICES SHALL BE PROTECTED DURING CONSTRUCTION.

179-189

8 184

PROPOSED INCLINOMETER PROPOSED INCLINOMETER IN RETAINING WALL

W

191 2

PROPOSED STRAIN GAUGE

15

PROPOSED EXTENSOMETER

200 8

PROPOSED TUNNEL CONVERGENCE SURVEY MONITORING 201

4

EXISTING PIEZOMETER

208

PROPOSED PIEZOMETER CANADA ST

7

KARANGA HAPE RD

4

235

MP03.2 B053BMP03.1

214

MP03.2 B065BMP03.1

MP04.2 B065BMP04.1

CROSS ST

R AC ON TER

E

PROPOSED TILTMETER

MP02.2 B053BMP02.1

POYNT

2 3 B054BMP10.1

CZK06SMP10

1

MP10.2 MP10.3 B054BMP10.1

54

2 3

32

65

MP05.2 B065BMP05.1

24

CZK06SMP09 CZK01SMP09 CZK03SMP13

238

CZK03SMP12

MP09.2 MP09.3 B054BMP09.1

MP02.2 CZK03SMP11 B065BMP02.1

239

CZK03SMP10

B054BMP0X.X

CZK03SMP09 MP01.2 B065BMP01.1 CZK01SMP08 CZK03SMP08

CZK01SMP07

URY

76

E

LAN

C MER

80-86

CZK02SMP16

B054BMP0X.X CZK03SMP07

MP08.2 MP08.3 B054BMP08.1

72

2 MP05.2 MP05.3 B054BMP05.1 MP06.2 MP06.3 B054BMP06.1 CZK03SMP04 CZK03SMP05 CZK01SMP06

70

CZK02SMP18

CZK02SMP17

23-31

CZK02SMP15

CZK02SMP14

2 3 CZK03SMP06 B054BMP07.1

CZK02SMP13

CZK02SMP12

CZK02SMP11

CZK02SMP10

68

CZK02SMP09

CZK01SMP05

CZK02SMP08

60

CZK02SMP07 CZK02SMP06

40-50

MP01.2 MP01.3 CZK02SMP04 B060BMP01.1 MP02.2 MP02.3 CZK02SMP05 B060BMP02.1 MP03.2 MP03.3 B060BMP03.1 MP01.2 MP01.3 B055BMP01.1

50

3

9 11-13

CZK01SMP04

246-254 CZK02SMP10

64

MP02.2 MP02.3 B052BMP02.1

MP01.2 MP01.3 B052BMP01.1

MP04.2 MP04.3 B060BMP04.1

MP02.3 MP02.2 B050BMP02.1 B050BMP01.3

50

PITT ST

60

B050BMP0X.X

MP03.1 MP03.3 MP03.2 B050B61-65

256 243

CZK01SMP03

MP05.2 MP05.3 B060BMP05.1

MP01.3 MP01.2 B049BMP01.1

CZK01SMP09

59

62

CZK01SMP02

258 4-6 55

MP02.3 MP02.2 B050BMP02.1 MP06.2 MP06.3 B060BMP06.1

49

MP01.3 MP01.2 B048BMP01.1

47

CZK01SMP08

2

CZK01SMP01

249

268 38 2 3 B060BMP07.1

8-10 MP02.3 MP02.2 B048BMP02.1

T ST

EAS 270

HAPE RD

259-261

1 2 B048BMP03.3

48

3 2 B048BMP04.1

1-7

KARANGA

12-14

MP03.3 MP03.2 B047BMP03.1

18

CZK01SMP07

RE S

FO

RD

SQ

29

20 278

284

BE

MP02.3 MP02.2 B047BMP02.1

25-27

267-281

16-18 CZK01SMP06

3 2 B047BMP01.1

16

14

47

23 12 290 21 8

SH1 S

.1 .2 BST20BMP01.3

Last Plotted: 2019-10-18

19 CZK01SMP05

16

.1 .2 BST22BMP01.3

CZK01SMP04

BST22BMP0X.X

15-25 BST22BMP0X.X .1 .2 BST22BMP02.3

17

292-300

283-287

T ST EAS

158

7

5 4

295 CZK01SMP03

3

GAL

Last saved by: DIONY(2019-10-18) Filename:

22-28

.1 .2 BST22BMP04.3

307

ST

CZK01SMP02

6A

S ATO

.1 .2 BST22BMP03.3

7 5 1

17

6B 312

16 309 CZK01SMP01

8A-8J

13 322-324

.1 .2 BST22BMP05.3

315-325 12

10

9

HO PE TO UN

27

SCALE

Link Alliance has prepared this document for the sole use of the client and for a specific purpose, each as expressly stated in the document. No other third party should rely on this document without the written consent of Link Alliance. Link Alliance undertakes no duty, nor accepts any responsibility, to any third party who may rely upon or use this document.

CLIENT:

DESIGNED

0

10

20

30

40

50

60

CREATOR ID : @CRL-SYW-GEO-IM-DRG-100000 70

80

90

100mm

SYW APPROVED

PROJECT:

DRAWN

----

TITLE:

DK

DESCRIPTION

APPROVED

DATE

CHECKED

DATE

----

----

This drawing is confidential and shall only be used for the purpose of this project. The signing of this title block confirms the design and drafting of this project have been prepared and checked in accordance with the Link Alliance quality assurance system to ISO 9001-2000.

CITY RAIL LINK PROJECT WIDE

ZONE:

DK

REV

COMPANY NUMBER : 6267870

SIZE A1

REVISIONS

ST

INSTRUMENTATION & MONITORING KARANGAHAPE STATION ENABLING WORKS PROJECT

DOCUMENT:

ZONE

DISCIPLINE

ORGANISTION

TYPE

SHEET

CRL - SYW - GEO - LKA - SKE - 702400

REVISION

####

GSMCP – Karangahape Station

APPENDIX E: Wall Deflection Limits to Control Settlement Effects

Page 38

| Karangahape Station Early Works

MEMO

DATE

5 November 2019

TO

Project Manager Karangahape Station

FROM

Lead – Groundwater and Settlement Effects

SUBJECT

Pitt Street and Mercury Lane Early Works, Karangahape Road Station – Wall Deflection Limits to Control Settlement Effects

Introduction This memorandum has been prepared as part of the proposed early works at Karangahape Road Station, and forms part of the City Rail Link (CRL) C3 project extending from Aotea Station to the North Auckland Line (NAL). The scope of these early works includes several works stages along Beresford Square and Mercury Lane, involving the demolition of existing structures, removal of trees and canopies, the excavation of combined service trenches, and stormwater / wastewater relocations by means of directional drilling methods.

Philosophy This memorandum outlines the wall deflection limits for the early works excavation support to ensure that the cumulative effects from the future main station works do not exceed the Consent trigger levels for the buildings adjacent to the area of works.

The magnitude of vertical movements due to excavation stress relief depends on the dimensions of the excavation and ground conditions, construction methodology and level of support stiffness. Both the construction methodology and designs have yet to be confirmed at the time of writing. The absence of excavation support design and construction methodology details prevents any meaningful assessment of the likely movement to be induced by the early works.

The GSMCP for the Karangahape Station early works will therefore adopt the trigger levels outlined in the existing Aotea to NAL Regional Resource Consent drawing CRL-SYM-RME-000-DRG-2640 Rev 4. Wall deflection limits have however been specified in this memorandum to prevent cumulative surface settlements from the early works and the future main station works from exceeding the Consent limits. The limits outlined in this memorandum are specified in the design requirements for the early works contractor.

Adherence to the specified wall deflection limits will be monitored on site by adopting a second set of “soft” or performance trigger levels for the proposed monitoring layout that consider the selected deflection limits and ground deformations. These limits will not be included in the monitoring or reporting requirements outlined in the GSMCP for the early works.

Link Alliance - Level 3, 12 Morgan Street, Newmarket, Auckland 1023

Description of Early Works The new Karangahape Station will be located at the junction of Pitt Street, Mercury Lane and Karangahape Road. Early works will be carried out to prepare the Karangahape Station site prior to commencement of the main construction works, and will include the relocation of network utilities located within the station footprint at Beresford Square, Pitt Street and Mercury Lane.

The majority of the relocation works will be carried out in shallow trenches which do not need excavation support. The relocation of the wastewater and stormwater lines will however involve deep excavations: 



  

The excavation of launch pits in Pitt Street (4 m x 3 m, maximum depth of 5 m bGL) and receive pits in Beresford Square (3m x 3m, maximum depth 3.5m bGL) at either end of the wastewater or stormwater line to be relocated; Combined service trench (up to 5m deep) or directional drilling launch and receive pits (4 m x 4 m, maximum depth 5 m) at the intersection of Mercury Lane and Cross Street to relocate wastewater and stormwater lines; Directional drilling (approximately 300 mm diameter bore) of the distance between pits; Rigging of the new pipe (250 mm diameter) through the drilled route; and Installing cased manholes (1.15 m diameter, maximum depth of 5 m bGL) along the length of the route along Beresford Square and at the positions of the launch pits once work has been completed.

The distances between these works and adjacent buildings vary, with the stormwater line (and associated pits/manhole excavations) generally within closer proximity to the building line than those excavations proposed for the wastewater relocation. The layout of the proposed early works at the time of writing are included in Appendix A of the GSMCP, and summarized in Table 1 below.

Table 1 Summary of early works and adjacent buildings b

Building Assessed Consent ID No.

Early Works Activity

Depth [m bGL]

Distance to nearest building [m]

Consent settlement alert level [mm]

Building address in consent

Alternative address

48

259—281 Karangahape Road

8-10 Beresford Square 12-14 Beresford Square

Manhole pit (SW)

3.2

0.57

8

49

251-253 Karangahape Road

14-16 Beresford Square

Manhole pit (WW)

5.0

1.0

9

50

61—65 Pitt Street

4.8

9

0.48

9

1.3

N/Aa

0.54

N/Aa

1.7

10

5.8

22

3.8

14

6.7

14

50 157 157 54 60 65 65

Pitt Street - launch pit 5.5 (WW) Pitt Street - launch pit 61—65 Pitt Street 4.0 (SW) 22-28 Beresford Beresford Square 4.0 Square retrieval pit (WW) 22-28 Beresford Beresford Square 3.0 Square retrieval pit (SW) 238 Karangahape Trench excavation 2 Mercury Lane 5.0 Road (WW) Mercury theatre 9 Mercury Lane 5.0 launch pit (SW) 1 Cross Street Cross Street - pit (SW) 5.0 Mercury plaza 1 Cross Street 5.0 retrieval pit (SW) Link Alliance - Level 3, 12 Morgan Street, Newmarket, Auckland 1023 -

a b

No trigger levels included in Consent for this building, tolerable settlement assumed to be < 5mm Measured from the edge of the excavation to building line, drawings attached as Appendix A to GSMCP

Existing Environment Ground Conditions Based on the available geological information, the general vertical stratigraphic sequence in the area comprises the following: 

Fill, generally varying in thickness between 2 - 3 m along the Beresford Square and Mercury Lane construction areas, but increases up to 4 m thick just south of the ridge crest at Karangahape Road and 5 - 6 m thick towards the lower slopes and towards CMJ;  Local alluvium deposits of Pleistocene age Tauranga Group Alluvium infill the heads of paleotributary gullies south of the ridge crest;  The thickness of the weathered and residual ECBF varies in the area, possibly as a result of preferential weathering down steeply inclined joints or faults leading to deeper weathering profiles in areas. The residual ECBF underlies the fill (where no alluvium deposits are present), ranging from 4 - 8 m and 3 - 6 m along Beresford Square and Mercury Lane respectively. The thicknesses of the weathered ECBF vary similarly, before grading into unweathered ECBF at depths between 46 and 54 m RL;  The channelised sandstone unit in the CMJ area is mapped throughout the Karangahape Station area. The base of the channelised sandstone unit approximates the vertical rail track alignment through this area. The unit is gently folded and faulted, with occasional swarms of joints which may be related to nearby faulting.

Refer to the C3 Geotechnical Baseline Report1 for further information regarding the Project geological setting.

Hydrogeology A review of the hydrogeological studies completed during prior CRL project stages and historic groundwater monitoring data from the Beresford Square and Mercury Lane regions indicates the presence of a shallow or perched groundwater level, varying between approximately 3 m bGL (high) to 6 m bGL (low).

Beneath the perched groundwater zone (at depths varying between approximately 8 to 10 m bGL), seasonally permanent saturation of the fill / alluvium / residual ECBF is assumed to occur, representing the top of the regional groundwater system in this area.

Refer to the PDP Groundwater Technical Report 2 for further information regarding the Project hydrogeological setting.

Sources of Settlement Effects The proposed early works will extend to a maximum depth of 5 m bGL, and will not intersect the regional groundwater regime. The effects of consolidation settlement due to the proposed early works are expected to be negligible, and only mechanical settlement effects (i.e. vertical ground movement due to excavation stress relief) are considered here.

1

Contract 3: Stations and Tunnels Alliance Geotechnical Baseline Report – C, Revision 1. Document No. CRL-SYW-GEO000-RPT-0017, dated 15 July 2019.

2 PDP, (2016). Auckland City Rail Link Aotea Station to North Auckland Line Construction and CRL Operation: Groundwater Technical Report. Prepared for Aurecon on behalf of Auckland Transport, dated May 2016.

Link Alliance - Level 3, 12 Morgan Street, Newmarket, Auckland 1023

Assessment Methodology To assess the amount of vertical surface settlement that could occur adjacent to the early works as a result of deflections of the pit or trench excavation support, the general approach outlined in CIRIA (2003)3 was used. This included the following assumptions: -

-

-

Support of all excavations will be of high stiffness, meaning top-down construction and props installed at high level; For the case histories summarized in the available literature, ẟ(vm) is equal to 0.5 to 0.7 ẟ(hm) for medium dense to soft soils, with an upper limit (for very soft clays) of ẟ(vm) = ẟ(hm). For this estimation and considering the ground conditions expected on site, a value of ẟ(vm) = 0.5 ẟ(hm) has been adopted; With a high stiff prop installed early during excavation, the maximum horizontal wall movement is not likely to be measured at the wall top but at a depth of some 0.7–0.9 times the maximum excavation depth (CIRIA, 2003), which in turn determines the point of maximum settlement from the edge of the excavation. For this assessment the distribution of maximum horizontal wall movement was conservatively assumed 0.9 times the maximum excavation depth; Distribution of ground surface settlement from the edge of the excavation and lateral deflection of the excavation support will follow the relationship illustrated in Figure 1-1 below.

Figure 1-1 Relationship between analysed lateral wall deflections and predicted ground surface settlements in stiff soil (CIRIA, 2003)

Results Based on the aforementioned philosophy, the distances between the early works excavations and adjacent buildings (Table 1) and the available settlement contours for the updated 9-car Karangahape Station design, maximum total ground surface displacement adjacent to the early works excavations should be restricted to 5mm or less. Following the methodology and empirical relationship outlined above, the design and construction methodology of the early works support will ensure to restrict wall deflections to 10mm or less.

Concluding Remarks

3

CIRIA C580, (2003). Embedded Retaining Walls – Guidance for Economic Design. London, ISBN 0 86017 580 4, 390 pp.

Link Alliance - Level 3, 12 Morgan Street, Newmarket, Auckland 1023

The memorandum aims to provide recommendations to ensure that any ground surface settlements from the early works combined with the effects from the main station works do not result in the exceedance of the trigger levels outlined in the Consent for buildings along this area of works.

The maximum tolerable deflections outlined here could be achieved using a high-stiffness support and topdown construction approach (following a conceptual design approach similar to the Aotea SP 2.2. trench along Albert Street for example).

At the time of designing the early works excavations it should however be confirmed that: 



The tolerable deflections outlined in this memorandum are achievable. In the event that the support of the respective excavations cannot be designed to the required deflection limits documented here, alternative control measures may be required.

The information used and assumptions made in this memo are valid for the final excavation design.

Should any of these not be representative of the actual design (e.g. position or dimensions of excavation changed, different construction methodology followed than that assumed here etc.), a reassessment of the relationship between the lateral deflection and resultant ground surface settlement will be required to confirm the suitability of design.

Prepared by: George Brink Lead – Groundwater and Settlement Effects

Reviewed by: Graeme Twose Senior Geotechnical Engineer

Link Alliance - Level 3, 12 Morgan Street, Newmarket, Auckland 1023

GSMCP â&#x20AC;&#x201C; Karangahape Station

APPENDIX F: Record of CLG Consultation A Karangahape CLG meeting was held on 17th September to discuss the Karangahape early works and for the CLG to provide comments / feedback on the CEMP and sub-plans, including this GSMCP. No comments were received from the CLG on this GSMCP.

Page 39

| Karangahape Station Early Works