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TL FOUNDATIONS

Fleet Strategy

Document TP. FL 01.02
16/10/2013

TL FOUNDATIONS FLEET STRATEGY
© Transpower New Zealand Limited 2013. All rights reserved.

TL Foundations Fleet Strategy
TP.FL 01.02
Issue 1
October 2013

COPYRIGHT © 2013 TR ANSPOW ER NEW ZEAL AND LIMITED . ALL RIGHTS
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Any breach of the above obligations may be restrained by legal proceedings seeking remedies including injunctions, damages and costs.

TL FOUNDATIONS
© Transpower New Zealand Limited 2013. All rights reserved.

TL Foundations Fleet Strategy
TP.FL 01.02
Issue 1
October 2013

Table of Contents
EXECUTIVE SUMMARY ...................................................................................................................... 1
SUMMARY OF STRATEGIES .............................................................................................................. 3
1 INTRODUCTION ....................................................................................................................... 5
1.1 Purpose ................................................................................................................................. 5
1.2 Scope .................................................................................................................................... 5
1.3 Stakeholders ......................................................................................................................... 5
1.4 Strategic Alignment ............................................................................................................... 6
1.5 Document Structure .............................................................................................................. 6
2 ASSET FLEET .......................................................................................................................... 7
2.1 Asset Statistics ...................................................................................................................... 7
2.2 Asset Characteristics .......................................................................................................... 10
2.3 Asset Performance .............................................................................................................. 17
3 OBJECTIVES .......................................................................................................................... 20
3.1 Safety .................................................................................................................................. 20
3.2 Service Performance ........................................................................................................... 20
3.3 Cost Performance ............................................................................................................... 21
3.4 New Zealand Communities ................................................................................................. 21
3.5 Asset Management Capability ............................................................................................ 21
4 STRATEGIES.......................................................................................................................... 24
4.1 Planning .............................................................................................................................. 24
4.2 Delivery ............................................................................................................................... 34
4.3 Operations ........................................................................................................................... 35
4.4 Maintenance ........................................................................................................................ 37
4.5 Disposal and Divestment .................................................................................................... 42
4.6 Capability............................................................................................................................. 42
4.7 Summary of RCP2 Fleet Strategies .................................................................................... 45
APPENDICES ..................................................................................................................................... 47
A GRILLAGE EXAMPLES .......................................................................................................... 48
B FOUNDATION CONDITION CODES ..................................................................................... 50
C GRILLAGE ENCASEMENT MODELLING .............................................................................. 53

TL FOUNDATIONS
© Transpower New Zealand Limited 2013. All rights reserved.

TL Foundations Fleet Strategy
TP.FL 01.02
Issue 1
October 2013

EXECUTIVE SUMMARY
Introduction
The condition and performance of tower and pole foundations is essential to the structural
integrity of transmission lines, and to ensuring reliability of supply to customers, and
maintaining public safety.
Our asset management approach for foundations seeks to maintain them in perpetuity, at
least lifecycle cost, and ensure the integrity and reliability of tower structures and the
conductors they support. We have long term programmes of work in progress to encase
deteriorated grillage foundations and maintain the asset health of foundation components.

Asset Fleet and Condition Assessment
The transmission line network includes approximately 25,000 structures that are supported
by foundations.
Most of our foundation fleet is used to support steel lattice towers, but we also have a small
number of monopole foundations and special types of foundations used in riverbeds. The
two main types of foundations supporting steel lattice towers are steel grillage and concrete
plug.
Our foundations are designed to withstand severe climatic loading conditions, and we
monitor and maintain them to ensure satisfactory performance. Structural failures of
foundations are rare, with only 12 recorded since 1963. These failures are usually associated
with extreme weather events.
Our condition assessment programme monitors and records the condition of foundations.
We forecast the future condition of each foundation based on its current condition and our
knowledge of the expected rate of degradation at each location. The forecast of future
condition provides the basis for asset management decision making.
Our condition assessment programme is risk-based, and the intervals between inspections
are adjusted based on the condition of the foundation and its criticality. Assessments are
performed more frequently as the foundation condition approaches the replacement
criteria. Foundations located in unusually aggressive environments, or deemed to be highly
critical, either to the Grid or for safety reasons, are also assessed more frequently.
Foundations include grillage types, consisting of steel buried in the ground, to which tower
footings are attached. Grillage foundations were widely used until the late 1960s, and
support about one half of our steel lattice towers. Buried steel grillage foundations are
subject to below-ground corrosion, leading to risk of foundation failure and subsequent
tower failure with consequent safety, environment and network performance impacts.
Overall, our foundation assets are in reasonable condition, reflecting recent work to encase
our ageing fleet of steel grillage foundations. The average age of the fleet of steel grillage
foundations is 57 years, while the average age of the entire foundation fleet is 44 years.

Foundation Strategies
The main strategy for the foundations asset fleet is the condition-based encasement of
deteriorated steel grillage foundations. Inspections carried out to date show that some of
our grillage foundations have deteriorated to the point where refurbishment is needed to

TL FOUNDATIONS FLEET STRATEGY
© Transpower New Zealand Limited 2013. All rights reserved. Page 1 of 58

TL Foundations Fleet Strategy
TP.FL 01.02
Issue 1
October 2013
keep them in satisfactory condition, and to avoid them declining to a point where tower
propping and major steel work replacement is required.
Since the mid-2000s, 1,700 grillages have been ‘converted’ to concrete over grillage
foundations by encasing them in concrete. A long-term programme of grillage encasement
work is now in place. We intend to refurbish foundations at 400 towers each year
throughout RCP2. Most expenditure identified in this strategy is for this refurbishment work.
The rest of the expenditure planned during the RCP2 period relates to repair of tower
baseplates and below-ground stubs that have corroded to the point where remedial work is
required. The plan involves refurbishing corroding foundation components at 630 sites each
year over RCP2.
A smaller amount of expenditure is allocated to the strengthening of existing undersized
foundations. The plan involves investigating foundations at 40 towers each year and
strengthening 8 each year over the RCP2 period.

Improvements
In our planning for the RCP2 period, we have made a number of improvements to the asset
management of foundations, including:
 improved modelling of condition degradation
 introduction of Asset Health Indices (AHI) to allow better comparison of asset
condition across fleets
 using asset criticality as an important factor in planning foundation asset works – in
particular refurbishments
 planning decisions that consider the whole-of-life cost of foundation assets, covering
Planning, Delivery, Operations, Maintenance and Disposal, as well as their impacts
on other assets, such as towers and poles
 using updated and more detailed building blocks for cost estimates.
For the grillage fleet, our approach remains unchanged from the RCP1 period.
Further improvements will include:
 refinement of condition assessment techniques and asset health models
 refinement of the asset criticality framework.

TL FOUNDATIONS FLEET STRATEGY
© Transpower New Zealand Limited 2013. All rights reserved. Page 2 of 58

Well maintained access tracks are essential to allow safe access to transmission line assets when responding to faults or performing routine inspections and maintenance. and ensure no grillage foundation has a condition assessment of less than 40 by 2033 (in 20 years). The strategy is to strengthen undersized foundations in all critical locations to minimise the risk of tower failure due to overloading. Strengthening undersized foundations reduces the chance of tower structure collapse (with significant implications for safety and reliability). Undersized Foundation Strengthening RCP2 Cost $4. The plan involves 64 bridge replacements over RCP2. generally by concrete encasement. tower structure collapses and conductor drops. or $51m over RCP2.FL 01. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. The plans will involve refurbishing approximately 400 grillages each year at an annual cost of $10. Bridge Replacements RCP2 Cost $6. The strategy is to replace bridges to ensure continuing safe and efficient access to transmission lines for maintenance and project works.2m. Grillage refurbishments extend the life of grillages and reduce the chance of foundation failure. All rights reserved. Capital Expenditure Grillage Refurbishments RCP2 Cost $51m A large number of grillages are deteriorating due to their age and environment.02 Issue 1 October 2013 SUMMARY OF STRATEGIES The following summaries include the main strategies and their respective costs during the RCP2 period (2015/16–2019/20). TL Foundations Fleet Strategy TP. all grillages that currently have a condition assessment of less than 30 by 2020. The strategy is to refurbish.4m Poor design process used for foundations constructed before 1983 has led to the occasional installation of undersized bored concrete foundations. grillages should be encased in concrete before the condition gets too poor (condition assessment less than 40) and it becomes necessary to prop the tower and replace steelwork at significant cost. Ideally. Page 3 of 58 . The plan involves investigating foundations at 40 towers each year and strengthening 8 each year over RCP2.1m A number of bridge replacements are required on access corridors to maintain access to the transmission lines and structure foundations.

The plan involves refurbishing corroding foundation components at 630 sites each year over RCP2 at an overall cost of $17.FL 01. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.5m A large number of ageing foundation components are deteriorating. The strategy is to refurbish corroding baseplates. Component refurbishments reduce the chance of foundation failure and tower structure collapse (with significant implications for safety and reliability). anchor bolts and cast-in stubs prior to onset of significant rusting.02 Issue 1 October 2013 Operating Expenditure Component Refurbishments RCP2 Cost $17. This refurbishment is based on the minimum condition assessment score of the four leg-based codes collected at each site. All rights reserved. Page 4 of 58 . TL Foundations Fleet Strategy TP.5m. Further detail on the above RCP2 strategies and discussion of the remaining strategies can be found in chapter 4. The typical threshold is condition assessment 50 before any significant rusting or loss of section is apparent.

TL Foundations Fleet Strategy TP. scope. The purpose of this strategy is to describe our approach to lifecycle management of our transmission tower and large pole foundation assets on the Grid. including BSI PAS 55:2008. and Maintenance. build. local and regional Councils. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. This document has been developed based on good practice guidance from internationally recognised sources. Key stakeholders include:  landowners  relevant Transpower Groups (Grid Development.2 Scope The scope of the strategy includes the foundations of towers and non-direct buried poles. Electricity Authority. 1. These activities include Planning. and strategic alignment of the foundations fleet strategy.1 Purpose We plan. and limited to:  grillage foundations (direct buried grid of steel)  concrete foundations with cast-in tower legs  concrete foundations with cast-in anchor bolts and tower/pole baseplates  large piled foundation structures (typically at river crossings and estuaries)  driven piles and wailings used for mounting poles in riverbeds. 1. maintain and operate New Zealand’s high-voltage electricity transmission network (‘Grid’) including the foundations that support conductor-bearing structures (towers and poles). Performance and Projects)  regulatory bodies: Commerce Commission. This includes objectives for future performance and strategies being adopted to achieve these objectives.02 Issue 1 October 2013 1 INTRODUCTION Chapter 1 introduces the purpose. Operations. stakeholders. 1. Delivery.3 Stakeholders Correct operation and maintenance of foundations is essential for the safe and reliable transport of electricity from generators to customers and distribution networks across public and private land. The strategy sets the high-level direction for fleet asset management activities across the lifecycle of the fleet. including distribution network businesses and generators. All rights reserved. Page 5 of 58 .FL 01. and the Environmental Protection Authority  Department of Conservation  service providers  customers.

and the daily activities of managing the assets.5 Document Structure The rest of this document is structured as follows. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. These strategies provide medium-term to long-term guidance and direction for asset management decisions and will support the achievement of the objectives in chapter 3.4 Strategic Alignment A good asset management system shows clear hierarchical connectivity or ‘line of sight’ between the high-level organisation policy and strategic plan. Chapter 4 sets out the fleet specific strategies for managing the assets. The strategy directly informs the portfolio asset management plans. TL Foundations Fleet Strategy TP. This document forms part of that line of sight by setting out our strategy on the foundations asset fleet. These objectives have been aligned with the corporate and asset management policies. Page 6 of 58 . Appendices are included that provide further detailed information to supplement the fleet strategy. Corporate Objectives & Strategy Asset Management Policy Asset Management Strategy Lifecycle Strategies Planning Delivery Operations Maintenance Disposal Foundations Strategy Foundations Plan Figure 1: Position of this Strategy within the Transpower Asset Management Hierarchy 1. It indicates where this fleet strategy and plan fit within the asset management system. This hierarchical connectivity is represented graphically in Figure 1. characteristics and their performance. Chapter 2 provides an overview of transmission line foundations including fleet statistics. Chapter 3 sets out asset management related objectives for the assets.02 Issue 1 October 2013 1. All rights reserved. and higher-level asset management objectives and targets.FL 01.

All rights reserved. which in turn support conductors. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. and spares  asset characteristics – including safety and environmental considerations.000 route km of transmission line. The quantities of each type (along with descriptions) are shown in Table 1.1 Asset Statistics This section outlines the foundations asset fleet population. safety and environmental and identification of risks and issues. It is important to maintain these in an appropriate condition through timely maintenance and refurbishment.02 Issue 1 October 2013 2 ASSET FLEET Chapter 2 describes the asset fleet with a focus on:  asset statistics – including population.1 Asset Population The Grid is made up of approximately 12. diversity. asset criticality. 2. maintenance requirements and interaction with other assets  asset performance – including reliability. This results in an increased risk of foundation and subsequent tower failure. 2.1.FL 01. As at 30 June 2012.000 foundation-supported structures on the network (such as towers). asset condition.2 Fleet Diversity Asset fleet diversity is an important asset management consideration. TL Foundations Fleet Strategy TP. Foundations play an important role on the Grid by supporting transmission line towers and poles. More than half of all tower foundations are original buried steel grillage foundations that are subject to corrosion. along with the diversity and age profiles of the physical assets. age profile. asset health. Foundations vary in size and type depending on the design loads. 2. soil type and the preferred construction practices of the day.000 transmission line support structures (such as towers and direct buried poles).1. Page 7 of 58 . supported by approximately 41. there are approximately 25.

All rights reserved. TL Foundations Fleet Strategy TP. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. essentially all foundations have been constructed with a concrete pile/plug and cast-in stub leg. Figure 2 depicts the diversity of the asset fleet. They were the preferred foundation type until the late 1960s when concrete foundations were introduced.1. Buried steel grillage foundations are the oldest type of tower foundation on the Grid and comprise more than half of all tower foundations.500 towers have baseplate and anchor bolt connections. This type of foundation and connection was installed between the mid-1960s and the late 1970s.02 Issue 1 October 2013 Foundation Type Description Population Towers Steel Grillage Grillages that have not yet been refurbished 12.FL 01. FOUNDATIONS. There are a large number of buried steel grillages in service that were installed up until the late 1960s which are deteriorating due to their age and environments. The proportion of concrete foundations will increase over time as new lines are constructed. Page 8 of 58 .667 Concrete Plug (bored dug) Currently preferred foundation type 9. Since then. some 6. BORED OR DUG (40%) OTHER TOWER FOUNDATIONS (3%) POLE FOUNDATION (1%) Figure 2: Foundations – Diversity 2. yet the bulk of the population are aged between 45 and 90.3 Age Profile Foundation assets have been installed progressively since the 1930s. Over 600 grillage foundations were refurbished by re-galvanising between 1992 and 2008 and are treated as being new from that date.913 Table 1: Foundation Types and Populations as at 30 June 2013 The type of foundation used has varied with time.DIVERSITY GRILLAGE (50%) CONCRETE OVER GRILLAGE (7%) CONCRETE PLUG.350 Concrete over Steel Grillage Refurbished grillage foundations (by encasement in concrete) 1. lines are divested or decommissioned and grillages are encased with concrete.971 Includes foundation types such as:  Driven Pile with Pile Cap – generally only used at Other river crossings or sites with very poor soils 653  Pad and Chimney – occasionally used at sites with poor soils  Raft and screw pile type foundations Poles Driven Pile and Wailings For mounting poles in riverbeds 272 Total 24. Of the concrete foundations.

works are always planned based on actual condition. One of the fleet’s main strategies relates to the effective replacement of grillage foundations through concrete encasement. Foundation Type Average Age Life Expectancy Comment Grillage 57 70 Varies from 50 to over 100 years Concrete over grillage 3 120 As for concrete plug Concrete plug. on average. Page 9 of 58 .Age Profile Foundation life expectancy The life expectancy for each type of foundation is shown in Table 2. This achieves. FOUNDATIONS . The actual life will depend on the specific site. and construction quality.500 1. bored or Assumes concrete/steel interface is maintained 36 120 dug periodically Other – Driven pile with Generally in more aggressive environment than 37 120 concrete pile cap standard concrete plug Other – Pad and 28 120 As for concrete plug chimney Other .000 500 0 0 10 20 30 40 50 60 70 ≥80 AGE (YEARS) Figure 3: Foundations .3). Life expectancy should be interpreted as the period after which the risk of failure is deemed unacceptable. While age is of interest for predicting future needs.2. not age (see subsection 2. an expected 120-year life extension with correct maintenance in place. TL Foundations Fleet Strategy TP.02 Issue 1 October 2013 The age profile of the foundation fleet is shown in Figure 3.AGE PROFILE GRILLAGE CONCRETE OVER GRILLAGE CONCRETE PLUG. It is based on observed life and typical condition degradation rates for each foundation type. weather exposure.FL 01.Other 27 50 Timber or steel piles driven into riverbeds foundations Table 2: Foundation Life Expectancy TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. BORED OR DUG OTHER POLE FOUNDATION 1. All rights reserved.

The risk is clearly dependant on land use. and is higher in urban environments and over busy roads than in back country rural environments. TL Foundations Fleet Strategy TP.2. All rights reserved.2 Asset Criticality Our approach to asset management has been adapted to recognise the differing levels of asset criticality. particularly when working in sensitive areas such as riverbeds. Highly critical assets will be designed and maintained to provide a higher level of reliability than less critical assets. Environmental issues are mitigated by working closely with the relevant regulatory bodies and landowners and by ensuring compliance with the Resource Management Act 1991 (RMA 1991). The methodology considers various aspects that would be impacted by a failure such as load carried. Environmental There is potential for significant environmental impacts when constructing or removing foundations. 2. A framework has been developed for transmission line assets. 2.1 Safety and Environmental Considerations We are committed to ensuring that safety and environmental risks are minimised at all times.FL 01.2 Asset Characteristics The foundations asset fleet can be characterised according to:  safety and environmental considerations  asset criticality  asset condition  asset health  maintenance requirements  interaction with other assets.02 Issue 1 October 2013 2. Page 10 of 58 . fire and physical impact damage. The most significant safety and environmental consideration for the foundations asset fleet is the prevention of a transmission structure failure. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Regular condition assessments and a robust design process are essential to minimise the risk of foundation failures. Prevention of tower failure Foundation failure leading to a tower failure and conductor drop is a significant safety consideration with risk of electrocution. and the level of redundancy. constraints that would be placed on the rest of the Grid. These characteristics and the associated risks are discussed in the following subsections. Further information on the asset criticality approach is provided in the document ‘Asset Risk Management – Criticality Framework’. the level of reliability required by the customers.2.

A separate condition assessment score is recorded for each. where a score between 91 and 100 is considered as new and 0 is seriously degraded to a point where failure could occur under everyday loading conditions.2. Thereafter. the foundation is incapable of carrying its full design loads. Subsections 2. no reliable non-intrusive method has been found to accurately predict which towers have corroded grillages. At a condition assessment score of 20. Despite numerous national and international trials. New foundation assets are first assessed just prior to the expiration of any defect liability period. All rights reserved. and will continue to refine and develop this throughout RCP2. in combination with asset health to determine prioritised replacement programmes. soil type and moisture content are all known to influence the grillage condition. Excavation and inspection (see Figure 5) is relatively TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.2 discuss how criticality is taken into account. Sites with a high consequence of failure may be assessed more frequently.FL 01. We are still at a relatively early stage in the development and application of safety criticality. The reliability and performance of these assets need to be managed carefully to minimise failure risks. If the condition assessments score is less than 50. FOUNDATIONS - NETWORK CRITICALITY LOW (45%) MEDIUM (39%) HIGH (16%) Figure 4: Foundations – Criticality Approximately half of the foundation asset fleet are classified as medium impact or high impact with respect to network criticality. These assessments produce a condition assessment score. Page 11 of 58 . Having severely rusting foundations on the network is a major risk that is compounded by the fact that they cannot be readily assessed for condition.1. Age.4 and 4. the foundation connection 2. The only reliable method of determining the condition of the buried part of the foundation condition is to dig and visually inspect.3 Asset Condition Regular condition assessments on foundations are carried out to assess their condition. Grillage foundations Many towers with buried steel grillage foundations are now showing corrosion on tower legs and bracing near the ground line. original galvanising quality. tower line assets are generally assessed every 8 years. the assessment period is reduced to 4 years.02 Issue 1 October 2013 Figure 4 shows the proportion of foundations in each criticality category. the foundation. 2.2. TL Foundations Fleet Strategy TP. During regular condition assessments the two locations assessed are: 1.

All rights reserved. at the grillage level.02 Issue 1 October 2013 expensive and also leads to accelerated corrosion. As discussed above. Assessment guidelines for foundations are included in Appendix B. varies from light to severe. Page 12 of 58 . Consequently grillage condition assessment has been carried out on a sampling basis. Analysis of the results shows that in 80% of cases the condition of the grillage is within 10 condition assessment points of the ground-line interface condition. TL Foundations Fleet Strategy TP. we now use the ground-line interface condition as a proxy for the lower grillage condition.000 towers have revealed that the extent of corrosion further underground.FL 01. Of the 7% outside 20 condition assessment points.000 towers have had their grillage foundations condition assessed to the base of the grillage. assessing the steel at this depth is disruptive and expensive. and is within 20 condition assessment points 93% of the time. in half the cases the grillage was in better condition than the ground interface. For concrete foundations with bolted connections or cast-in stubs. Excavations undertaken on some 1. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.5 to 3m below ground level. Figure 5: Excavated Grillage The bottom of a grillage foundation is typically 2. the connection relates to the steel/concrete interface. Less than 1. as oxygen will enter into what was a largely oxygen-starved system. For grillage-type foundations the connection is deemed to be the steel from 100mm above ground level to 300mm below. Given the high cost and landowner disruption associated with accurately assessing the condition of the buried part of the foundation.

Concrete foundations with cast-in stub legs are generally in good condition. Assessment guidelines for foundations are included in Appendix B. As for grillages.000 3. the steel cleaned.type foundations is porous and has led to mortar crumbling. Typically. In extreme cases a small area of concrete is broken out. 1 Using ground-line condition as a proxy for grillage foundations. Poor quality dry-pack mortar originally used under baseplate.02 Issue 1 October 2013 FOUNDATIONS . a large number of foundation connection components are deteriorating due to their age and environment. BORED OR DUG OTHER 6. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Foundation connection components For concrete foundations with bolted connections or cast-in stubs.000 5.000 4. the connection relates to the steel/concrete interface. The majority of the fleet has a condition assessment score of above 40 although approximately 1. the foundation connection becomes a cast-in stub-type arrangement.CONDITION GRILLAGE CONCRETE OVER GRILLAGE CONCRETE PLUG. but an increasing number are starting to corrode at the concrete and steel interface. Note that once a grillage foundation is refurbished by concrete encasement.FL 01.000 1. TL Foundations Fleet Strategy TP.000 2. All rights reserved.400 (or 11%) of grillage foundations are at or below condition assessment 30. the rust does not extend very far into the concrete (<20mm). Refurbishment by blasting and painting has proven highly successful. and the area repaired by grouting. Page 13 of 58 . Moisture ingress under the baseplate has subsequently led to corrosion of the anchor bolts and baseplate (which is not visible until the grout is removed).000 0 0-10 11-20 21-30 31-40 41-50 51-60 61-70 71-80 81-90 91-100 CONDITION ASSESSMENT (CA) SCORE 1 Figure 6: Foundations – Asset Condition Figure 6 shows the distribution of condition assessment codes for foundations.

000 1. 2.4 Asset Health The AHI reflects the forecast remaining life for any given asset – in effect. or is uneconomic). and so affect the rate of corrosion of steel towers.CONDITION BASEPLATE / ANCHOR BOLT CAST IN SITU STUB LEG 3.2. More details on our asset health methodology are set out in the document ‘Asset Risk Management – Asset Health Framework’. The AHI forecast of remaining useful life is based on modelling deterioration or risk that cannot be addressed by normal maintenance (where maintenance to address the deterioration or risk is not possible/practical. TL Foundations Fleet Strategy TP.02 Issue 1 October 2013 FOUNDATION COMPONENTS . At this point. For transmission line foundations. which is used to optimise the level of investment in the fleet. such as total replacement of the asset or refurbishment that significantly extends the original design life. Foundation component refurbishment is based on the minimum condition assessment score of the four leg-based codes collected at each site. it is an assessment of current and future asset ‘fitness for purpose’. The AHI is calculated using:  the current condition of the asset  the age of the asset  the typical degradation path of that type of asset  any external factors that affect the rate of degradation.000 2. Asset health information is used in combination with asset criticality data to assign an overall priority to each asset. Page 14 of 58 . major intervention is required. Assessing asset health is particularly important as it is used to understand the deterioration profile of asset fleets and to forecast and prioritise replacement and refurbishment activities. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Asset health indicators provide a proxy for the probability of failure in asset risk management analysis. this is when the foundation can no longer be relied upon to carry its design loads.FL 01.000 0 0-10 10-20 20-30 30-40 40-50 50-60 60-70 70-80 80-90 90-100 CA SCORE Figure 7: Components – Asset Condition Figure 7 shows the condition of foundation components. such as proximity to the coast. We are still at a relatively early stage in developing and applying asset health indicators. The typical threshold is condition assessment 50 before any significant rusting or loss of section is visible. All rights reserved.

TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. The more replacements we do. Asset Health Decreasing Increasing Criticality Figure 8: Prioritisation Approach Asset health for the foundation fleet has been calculated assuming replacement criteria at a condition assessment score of 20 for all foundations except grillages where replacement is modelled at CA 30. 2 Literature on in-ground corrosion of galvanised steel suggests the corrosion rate is roughly linear while galvanising is still there. While the overall health of the tower foundations is generally good. CA 30 has been selected for grillages to account for the uncertainty regarding their below-ground condition. FOUNDATIONS.2 For grillages. ground-line interface condition has been used as a proxy for grillage condition as discussed in subsection 2. due to the heightened risk of them failing. As an example.2. but may actually decrease once corrosion starts. the better our understanding in this area will be. A linear degradation rate from the original installation date to the most recent condition assessment score is assumed. the failure risk changes very little.FL 01.02 Issue 1 October 2013 The association of asset health to the probability of failure is not strongly formed until a condition assessment score of 20 or below is recorded. Figure 8: shows that prioritisation is based on a combination of condition (remaining life) and criticality. a number of ageing foundations have a relatively poor condition. TL Foundations Fleet Strategy TP.ASSET HEALTH (12/13) 12+ YRS (90%) 7-12 YRS (4%) 2-7 YRS (3%) 0-2 YRS (0%) NOW DUE (6%) Figure 9: Foundations – Asset Health Indices The greatest asset management challenge for the ageing fleet of foundations is managing the corrosion of buried steel grillages. ‘Now Due’ grillages with a condition assessment score under 30 are a higher priority than a high criticality site just reaching 40. the risk of failure increases markedly. All rights reserved. there is a slight increase in the risk of failure. Asset health information is used in combination with asset criticality data to assign an overall priority to each asset. which is used to optimise the level of investment in the fleet. Below a score of 30.3 above. As the condition assessment score reduces below 20. Between a score of 100 and 30. The manner in which asset health is taken into account in the management of the assets is described further in chapter 4. Note: maintenance works such as refurbishment of baseplates and anchor bolts must be carried out periodically to achieve these predicted lives (as noted in Figure 9). Page 15 of 58 .

repairs  Maintenance Projects.02 Issue 1 October 2013 2. The most common types of maintenance carried out on lines assets are:  preventive maintenance. In addition. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. condition assessments .3. Corrective maintenance Typical maintenance activities for foundations include removing soil and vegetation from the top of concrete foundations and installing protection works such as rip rap in rivers. Each year a number of sites require stabilising work and repairs to avoid failure. TL Foundations Fleet Strategy TP. A ground-based patrol visits each structure/span and walks the conductor line.2. fault response . which are programmes of works (essentially made up of small projects) used to address repetitive issues identified through preventive maintenance or fault responses. including: .5 Maintenance Requirements This subsection describes the maintenance requirements of the foundation fleet. Preventive maintenance Line patrols are generally performed once a year on every transmission line asset. to visually identify any defects. Page 16 of 58 . The most common fault response and repair work required for foundations relate to foundation failures due to land subsidence or rapid soil erosion. Repair jobs are raised in the Maintenance Management System and the maintenance contractors are responsible for carrying out this work. All rights reserved. we periodically undertake maintenance projects. servicing  corrective maintenance. Detailed maintenance requirements are included in the relevant service specification documents. scouring and subsidence  third party excavation or construction around tower foundations. In extreme cases a structure may be relocated. condition assessments are carried out on a cyclic basis and entail a detailed inspection of the structure and span.FL 01. The assessment produces a condition assessment score for various components and a defect list. including: . As discussed in 2. The main purpose of the patrols is to identify defects and sites with very high safety criticality that may then be patrolled more frequently. if possible. The Maintenance Lifecycle Strategy provides further details on our approach to the above maintenance works. Contributing factors include:  severely damaged foundations  geotechnical risks due to slips. A patrol report identifies defects required to be rectified.2. These requirements have informed the maintenance strategies discussed in section 4.4.

6 Interaction with other Assets The foundations programme is closely aligned with conductor and tower works. those with baseplates and anchor bolts and those with cast-in stubs.4. Examples of past maintenance projects are set out below.3.3. as any new tower work requires foundation work. the remaining seven were due to high wind events pulling the foundations from the ground. and to improve performance.9m Table 3: RCP1 Spend on Maintenance Projects 2. Historic spend – maintenance projects Table 3 provides an overview of historic maintenance project expenditure. 2.1m $6.2. 2. Maintenance projects would not be expected to increase the original design life of the larger assets.FL 01. only one tower foundation failure has occurred and was due to river washout. Since 1963 there have been 12 foundation failures. with established modern design practices the probability of foundation failure is low. All are subject to corrosion.0m $2. Similarly.3. Connection component refurbishments Foundation connection components comprise two types. Reliability is measured primarily by the frequency and length of outages. Maintenance jobs are typically run as a project where there are operational and financial efficiencies from doing so. Page 17 of 58 . This constitutes a RCP2 strategy and is discussed in more detail in subsection 4.1. Since 2005.4.8m $2. conductors were transferred to a temporary structure prior to the foundation (and tower) failure. Future maintenance projects are discussed in subsection 4. The refurbishment of corroded steel and the replacement of mortar prior to significant degradation in baseplate and anchor bolt foundations are carried out to ensure that structural integrity is maintained. Towers supporting a line being supplied with a new (or refurbished) conductor may require foundation strengthening due to heavier conductors and higher tension being used. The drivers for maintenance projects include asset condition. the steel at the concrete interface of cast-in in situ foundation legs is painted prior to significant rusting. TL Foundations Fleet Strategy TP. Five failures were caused by land movement or river scour. These integration processes are managed through the Integrated Works Planning (IWP) processes discussed in subsection 4. mitigating safety and environmental risks. land movement and washout do occur. Project 2009/10 2010/11 2011/12 Total Various $2.02 Issue 1 October 2013 Maintenance projects Maintenance projects typically consist of relatively high-value planned repairs or replacements of components of larger assets. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. While foundation failures due to extreme climatic loading.1 Reliability Achieving an appropriate level of reliability for our asset fleets is a key objective as it directly affects the experience of our customers. All rights reserved.3.3 Asset Performance This section describes the historic performance of foundation assets and any associated risks and issues. In this instance.

such as tower foundations).3. Undersized foundations Studies have revealed that concrete foundations built before 1983 were usually designed based on very limited soil testing and with assumptions made about soil properties. All rights reserved.2 Safety and Environmental Performance No people have been harmed by any foundation failure on our network. Approximately 10% of grillages and foundation components are now corroded to the point of requiring replacement or refurbishment. TL Foundations Fleet Strategy TP. suggest that under-strength foundations still exist in some cases. Limited effectiveness of near-surface visual inspections Severely rusting foundations on the network present a major risk. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. 2. Structures with concrete pile foundations built before 1983 continue to be investigated. Some below-ground sampling has been carried out to inform the asset management approach.FL 01.3 Performance Benchmarking International Transmission Operations & Maintenance Study (ITOMS) involves performance comparisons (including reliability) between 27 utilities. Page 18 of 58 . leading to undersized foundations occasionally being installed. A slight conservative approach is therefore warranted. ITOMS considers overall transmission line performance (not on an asset type basis. 2. compounded by the fact that foundations buried at depth cannot be readily condition assessed. with the bulk of the fleet now aged between 45 and 90. Age profiles Grillage foundations are the oldest type of foundation. Age-based deterioration is the major driver of the work programme related to this asset fleet.02 Issue 1 October 2013 In many instances. We maintain a register of problematic areas and at-risk structures are monitored after major weather events. Recent studies. including full-scale foundation testing.3 2. Our environmental record is considered to be very good. with priority given to sites whose failure would pose significant risk to people. This overall performance is considered in the Conductors and Insulators fleet strategy.4 Risks and Issues This subsection briefly discusses risks and the identified issues relating to the foundation asset fleet. The risks associated with foundation corrosion include rapidly increasing costs to maintain if left too late and reduced structural strength that could lead to foundation and tower failure. however there is a risk that the condition of any buried grillage is worse than predicted. condition assessments and line patrols identify foundation issues before towers fail.3. property or the Grid. as we work closely with authorities and landowners to mitigate any adverse effects associated with our works. 3 Details can be found in the Conductors and Insulators fleet strategy.3.

TL Foundations Fleet Strategy TP.02 Issue 1 October 2013 Foundation failure Foundation failures can result in tower collapses and conductor drops. fatalities and injuries from electrocution or impact of falling objects. Maintenance managers and contractors monitor at-risk structures after major weather events. We maintain a register of problematic areas. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. All rights reserved. Washouts and landslides Poor slope stability and/or river scouring have been significant causes of foundation failures. These events can cause fire on public or private land. property damage and loss of power supply. Page 19 of 58 .FL 01.

Page 20 of 58 . These high-level objectives are supported by a number of fleet specific objectives. All rights reserved.1 Safety We are committed to becoming a leader in safety by achieving injury-free workplaces for our employees and to mitigate risks to the general public. Safety is a fundamental organisational value and we consider that all incidents are preventable. Grid Performance objectives state that a set of measures are to be met for GXPs based on the criticality of the connected load. at least lifecycle cost. 3. Service Performance Objectives for Foundations .02 Issue 1 October 2013 3 OBJECTIVES Chapter 3 sets out asset management objectives for transmission line foundations. . these objectives have been aligned with the corporate objectives. Further objectives in the following areas have been defined:  Safety  Service performance  Cost performance  New Zealand communities  Asset management capability. Recognising the reduced level of control we have in relation to public safety. No major failure of foundation assets with high or very high safety criticality. Our overarching vision for our foundations fleet is to maintain them in perpetuity. Chapter 4 discusses the strategies to achieve them. 3. and higher-level asset management objectives and targets as set out in the Asset Management Strategy. and we will work towards these being formally linked in the future. Safety Objectives for Foundations .4. We have specified our network performance in terms of Grid Performance (reliability) and Asset Performance (availability) in our Asset Management Strategy. The current rate is 1.2 every 5 years. As described in section 1. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. TL Foundations Fleet Strategy TP. we will take all practicable steps to ensure transmission line assets do not present a risk of serious harm to any member of the public or significant damage to property. Less than 1 foundation failure every 5 years. and to ensure the integrity and reliability of tower structures and the conductors they support.2 Service Performance Ensuring appropriate levels of network performance is a key underlying objective. In addition Asset Performance objectives linked to system availability have also been defined. These objectives are set out below. Zero injuries caused by foundation failures.FL 01.

TL Foundations Fleet Strategy TP. construct and maintain foundations to minimise lifecycle costs while meeting required levels of performance. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Maintain effective relationship with stakeholders affected by foundation works. We are committed to implementing systems and decision- making processes that allow us to effectively manage the full lifecycle costs of our assets. Compliance with RMA 1991 requirements. Relationships with landowners and communities are of great importance to us and we are committed to using asset management approaches that protect the natural environment. . 3.FL 01. Page 21 of 58 . Minimise stakeholder disruption by packaging work into blocks of consecutive spans wherever possible. . . No damage to third party property due to foundation failures. Cost Performance Objectives for Foundations .3 Cost Performance Effective asset management requires optimising lifecycle asset costs while managing risks and maintaining performance. we have set out a number of maturity and capability related objectives. Disestablished site foundations should be re-instated to their former natural forms to allow the land to recover. . . The rest of this section discusses objectives in these areas relevant to the foundation asset fleet.5 Asset Management Capability We aim to be recognised as a leading asset management company. All rights reserved. Minimise cost of capital projects through long-term resource planning of service providers. Minimise cost of works by packaging work into blocks of consecutive structures wherever possible.4 New Zealand Communities Asset management activities associated with the foundation asset fleet have the potential to impact on the environment and on the daily lives of various stakeholders. Design. . To achieve this. such as erosion and sediment control during site works.02 Issue 1 October 2013 3. . These objectives have been grouped under a number of processes and disciplines that include:  Risk Management  Asset Knowledge  Training and Competency  Continual Improvement and Innovation. 3. Improved efficiency through extension of the planning horizon. New Zealand Communities Objectives for Foundations .

2 Asset Knowledge We are committed to ensuring that our asset knowledge standards are well defined to ensure good asset management decisions. based on the criticality framework. TL Foundations Fleet Strategy TP. . including the risk-weighted cost of circuit unavailability (such as the cost of an outage or the increased chance of outage due to reduced redundancy). Develop a risk-based model for assessing the trade-offs between different work methods (such as live line techniques).1 Risk Management Understanding and managing asset-related risk is essential to successful asset management. .FL 01. . including root cause analysis. This asset knowledge must be captured and recorded so that it can be conveniently accessed.02 Issue 1 October 2013 3.5. Enhance the failure and incident records system to improve consistency and usefulness of data. 3. We currently use asset criticality and asset health as proxies for a fully modelled asset risk approach. Page 22 of 58 . Improve the condition assessment consistency through improved guidelines (such as photographic examples). Risk Management Objectives for Foundations . Finalise and implement the safety and network criticality categorisation systems for foundation applications. We are currently at an early stage of implementing the framework as we work towards formal and consistent integration of asset criticality into the asset management system. Continuously improve the asset health modelling of foundations. Expand knowledge of foundation condition through scheduled condition assessment and analysis of as-found condition during the foundation replacement and refurbishment programme. . Formalise and implement an asset management approach that is differentiated by network and safety criticality. Asset Knowledge Objectives for Foundations . including experience from assets on our network and condition information. We have commenced this by prioritising fleet replacement expenditure programmes.5. Relevant asset knowledge comes from a variety of sources. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. All rights reserved. . Asset criticality is a key element of many asset management systems.

Training and Competency Objectives for Foundations .4 Continual Improvement and Innovation Continual improvement and innovation are important aspects of asset management. Increase and then maintain the in-house skill base with regard to asset management principles and application. Continue to monitor new and emerging foundation technologies and designs. Continuous Improvement and Innovation Objective for Foundations . 3.FL 01. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. A large source of continual improvement initiatives will be ongoing learning from our asset management experience. competent and motivated staff to improve our asset management capability.02 Issue 1 October 2013 3. Page 23 of 58 . . All rights reserved.5.3 Training and Competency We are committed to developing and retaining the right mix of talented. TL Foundations Fleet Strategy TP. All foundation works to be carried out by service providers that are suitably qualified and competent for the specific tasks required.5.

training and competence.1.2. The planning lifecycle strategies for these processes are described in the subsections below. The majority of capital expenditure consists of grillage refurbishment.FL 01. and replacement and refurbishment works. TL Foundations Fleet Strategy TP.1. We support our planning activities through a number of processes.  Planning Lifecycle Strategy  Delivery Lifecycle Strategy  Operations Lifecycle Strategy  Maintenance Lifecycle Strategy  Disposal Lifecycle Strategy This chapter also discusses capability related strategies which cover asset knowledge. Planning activities Planning activities are primarily concerned with identifying the need to make capital investments in the asset fleet. compliance with Grid reliability standards. including:  IWP  cost estimation. Scope of strategies The strategies focus on expenditure that is planned to occur over the RCP2 period (2015– 2020).02 Issue 1 October 2013 4 STRATEGIES Chapter 4 sets out the fleet specific strategies used to manage the foundations asset fleet.1 Planning This section describes our strategies relating to the planning lifecycle phase of the foundations fleet and identifies where and how these strategies support the objectives for the overall fleet. while operating expenditure is mainly covered by section 4. All rights reserved. These strategies provide medium-term to long-term guidance and direction for asset management decisions and will support the achievement of the objectives in chapter 3. These drivers include demand growth. but also include expenditure from 1 July 2013 to the beginning of the RCP2 period and some expenditure after the RCP2 period where relevant. Page 24 of 58 . technology changes and failure TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. which is described in subsection 4. Capital expenditure planned for the period is covered by the strategies in section 4. The strategies are aligned with our lifecycle strategies below and the chapter has been drafted to be read in conjunction with them.4. The main types of investment considered in this strategy are enhancement and development. Capital investment drivers Categories of capital investment generally have specific drivers or triggers that are derived from the condition of the overall system or from individual assets. 4.

and strengthen other foundations as part of specific enhancement projects.FL 01. which is driven by failure risk. It does not improve its attributes. the cost for such foundation work is currently included in the relevant conductor projects. including strengthening and relocation. Any asset management related costs following their initial installation will be managed through the foundations portfolio. to support new structures or to enable upgrading of conductors. enabling better works prioritisation. Following completion of the project. see the Conductors and Insulators fleet strategy. Condition driven projects Foundation replacement and refurbishment works are primarily triggered by asset condition represented by condition assessment score.1. 4 For more details. These projects drive the need to invest in foundations. In the next few years. where the priority is higher for assets where the consequence of failure is higher. Page 25 of 58 . We use condition assessment data gathered during refurbishment programmes to model the condition of grillages that have not yet been refurbished. which is carried out to ensure that an asset is able to perform its designated function for its normal life expectancy. Specific examples that drive capital investment in foundation assets include:  new line developments or uprating of existing circuits. The timing and cost of works will be driven by the relevant conductor works. Refurbishment is expenditure on an asset that creates a material extension to the end of life of the asset. TL Foundations Fleet Strategy TP. Replacement is expenditure to replace substantially all of an asset. This is distinct from maintenance work. System growth projects principally include new greenfield lines or the uprating of existing lines. As part of uprating projects. 4. foundations that do not comply with current design standards are strengthened. Facilitate line projects Modify existing foundations. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.1. which is driven by demand  condition of grillages and other foundation components  foundation strengthening and replacements. The tower investments are undertaken to meet expected system growth and to ensure appropriate reliability for customers. to increase reliability. Prioritisation is undertaken on the basis of asset health and asset criticality.2 Replacement and Refurbishment This subsection describes replacement and refurbishment strategies for the foundations fleet. we will install a number of new tower structures and their associated foundations. Specific interventions have been defined for foundations based on their condition and informed by their relative criticality.4 4. the costs will be allocated out to the relevant foundation asset.1 Enhancement and Development The most important driver for new foundation investments is the facilitation of new or strengthened towers.02 Issue 1 October 2013 risk (indicated by asset criticality and health measures). which may require stronger structures and foundations. All rights reserved. From a planning perspective.

TL Foundations Fleet Strategy TP. In some locations it may be impractical to transport concrete to site. Most significantly. Page 26 of 58 . Between 1992 and 2008. and put back in the ground (in another location to allow a rolling programme). 5 For more details on encasement costs. re- galvanising and replacing them. less risk to the structure during installation. see the cost section of the Grillage Refurbishments Programme strategy.  Replace with a new grillage designed specifically for the given location – the cost is approximately 1. the existing grillage should be refurbished or a new grillage installed. they bring the steel interface above ground.4 times that of encasement. and so reducing risk. Grillage refurbishments – approach Use concrete encasement designs as the preferred refurbishment option wherever they can be installed in a cost effective manner. concrete encasement of the tower legs has become the preferred refurbishment option. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. The proportion of grillage replacements is predicted to be small (under 10%) compared to the number of concrete encasements. those options that have been discounted include  Excavate and remove grillages for re-galvanising. These interventions and their rationale are set out below. Specifically. simplifying maintenance and condition assessment requirements. Concrete encasement designs have many advantages over buried steel. and we will still be left with buried steel.02 Issue 1 October 2013 Refurbished foundations will be designed to carry the anticipated design loads of likely future upgrades on the line. In these instances.6 times the cost of encasement and we will still be left with buried steel.5 there is no scope for strengthening. increased performance and reduced requirements for future condition assessment. Alternative approaches for grillage refurbishments have been assessed. over 600 grillage foundations were refurbished by removing.FL 01. All rights reserved. including lower cost. Since then. Cost is approximately 1.

. Background Grillage foundations are simply galvanised steel members buried underground. Over 12.000 towers on the network still have grillage foundations — 50% of the foundation fleet. . .700 grillages have been ‘converted’ to concrete over grillage foundations by encasing them in concrete. refurbish. Concrete Encasement Like-for-Like Replacement Figure 10: Decision process for grillage encasement versus replacement Grillage Refurbishments Programme By the end of the RCP2 period. The actual condition of the grillage fleet for the majority of towers is therefore unknown. In some Concrete encasement locations this is not practical due to the cost or replacement of getting concrete to the site. Ensure no grillage foundation has a condition assessment score less than 40 by 2033 (in 20 years). TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. 1. with some now almost aged 90. Preference is to complete concrete encasement wherever possible to bring interface issues above ground where they can be managed by non-intrusive inspections and remedial work. Investigations have found that many of these buried steel members are severely corroded. Yet grillages cannot be readily condition assessed because they are buried up to 3m below ground. Grillage selected if worst leg condition is CA 40 or below. Since the mid-2000s. Where costs of concrete encasement exceed like-for-like replacement by greater than 30%. Grillage may be prioritised again if there reaches CA 40 is only 1 low coded leg with the other 3 significantly better coded. complete like-for-like replacement. TL Foundations Fleet Strategy TP. Grillage Condition . All rights reserved. preferably by concrete encasement. This poses a significant risk to the network.FL 01. all grillages that currently have a condition assessment score less than 30. Page 27 of 58 . The average grillage age is 57 years.02 Issue 1 October 2013 The flowchart (in Figure 10) outlines the decision process used to decide on concrete encasement or like-for-like replacement.

It assumes a linear degradation rate from the original installation date (at condition assessment 100) to the most recent ground-line condition recording. TL Foundations Fleet Strategy TP. Page 28 of 58 . Condition assessment scores less that 30 would require some replacements and more extensive preparation works. Modelling grillage condition As discussed in subsection 2. At a condition assessment score of 30. a condition assessment score of 30 to 35 is the optimal time to encase a grillage in concrete. metal loss has certainly occurred. because definitive condition information cannot be readily observed. otherwise it will be necessary to replace significant steelwork. Foundation inspection records for these structures were interrogated to determine the pre- refurbishment condition and inspection date and used to derive the degradation rates for these structures in the model. as such a condition assessment score of 40 is deemed the most appropriate condition to target for encasement. and in 93% of cases it is within 20 condition assessment points. grillages should be encased in concrete before the condition gets too poor.02 Issue 1 October 2013 Assessing condition The ground-line steel condition can be used as a proxy for the grillage condition provided a somewhat conservative approach is taken with regard to refurbishment or replacement timing. In the late 1990s and early 2000s approximately 2. On balance. Propping a tower and removing members increases cost significantly. with the other half being worse. However.5% chance that its condition assessment score is 20 or less. In 80% of cases it is within 10 condition assessment points. Foundations with such members have reached replacement criteria and should be targeted for replacement as soon as possible. investigations carried out on close to 1. All rights reserved. then continues linearly to forecast future condition.2.200 structures had their ground-line interfaces refurbished by blasting and applying thermal zinc spray.5% chance that a tower with a ground-line interface condition assessment score of 40 may have a grillage condition assessment score between 20 and 30. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Generally.000 towers have revealed that the condition of the steel near ground-line (100mm above to 300mm below ground) is generally quite similar to that of the more deeply buried steel. Foundations with a condition assessment score of 30 can be concrete encased without the need for member replacements.4. Optimum replacement time Foundation members with a condition assessment score of 20 have lost over 10% cross section and cannot be relied upon to carry their design loads.2. but the members have not yet reached replacement criteria. we have created a model to predict current and future grillage condition. and a 3.FL 01. Ideally. At a condition assessment score of 40 the galvanising is gone and there are initial signs of metal loss. The model also includes grillage foundations that have had their ground-line interfaces refurbished. half the grillages were in better condition than the ground-line steel.3. As discussed in subsection 2. We have good ground-line condition data for every foundation. This means there is a 6. a conservative approach will be adopted. Their ground- line condition is therefore no longer a good proxy for grillage condition. It also increases safety risk to workers and the potential risk of tower failure during the works.

The data for these is somewhat less robust than for non-refurbished sites.000 grillages will fall below 40. All rights reserved. Beyond 2033. However. To achieve this. The plan is therefore to refurbish foundations at 400 towers each year throughout RCP2. Modelling (see Appendix C) has determined that 350 grillage encasements each year is the optimum volume for the programme to achieve the above objectives. it can be expected that the original installation date. As an example.02 Issue 1 October 2013 The following assumptions are used within the grillage condition model.6 It should be noted that 350 grillage encasements each year represents an ideal result. TL Foundations Fleet Strategy TP. soil conditions and construction are effectively equivalent at each property. the following condition-based objectives have been developed: 1. all grillages will have been refurbished by 2045.400 have a condition assessment score less than 30. Plan to have no grillages with a condition assessment score under 30 by end of RCP2 (2019/20) 2. Grillage refurbishment objectives and plan Based on available condition information and reflecting the optimum replacement timings. in general. It is estimated that for every 350 foundations refurbished based solely on condition. refurbish grillages when they reach a condition assessment score of 40. Refurbishment volumes of 200 and 300 failed to achieve the grillage refurbishment objectives. By that time.FL 01. however they do pose a risk.  Life expectancy of an encased grillage is 120 years from the encasement date. If the programme continues at 400 grillages each year. Over the next 20 years the condition assessment score of an additional 4. 6 For the first objective the minimum required numbers are (1400 + 880)/7 years = 326/year. based on condition data gathered from the previous 10 years.  Grillage condition assessment score is taken as the worst of the leg interface condition codes. They will be targeted for refurbishment before the end of RCP1 period. the youngest original grillage will be almost 80. Condition assessment data of the excavated steel will be collected while refurbishing the grillage foundations. while for the second objective the minimum required numbers are (3000 + 4000)/20 year = 350/year TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. a further 50 will be refurbished somewhat early. There is a small number predicted to have a condition assessment score less than 20: these are all at sites where interface refurbishments were carried out.000 grillages are predicted as having condition assessment score below 40. approximately 3. one key objective is to minimise disruption to stakeholders. This inevitably means that some works are carried out slightly earlier than they would be if based solely on condition. Page 29 of 58 . As of June 2013. it is desirable to refurbish all grillages on a single property at one time. Plan to have no grillages with a condition assessment score under 40 within 20 years (2032/33) 3. At the end of RCP2. as deliverability constraints and needs for scale efficiency will lead to foundations being addressed differently to that modelled. Of these 1. we will re-evaluate the appropriateness of the chosen plan.  Degradation rate is linear. By 2020 the condition of 880 grillages will fall below condition assessment 30.

500 1.ASSET HEALTH FOUNDATIONS . To date. Grillages with a condition assessment score under 30 are a higher priority than a high-impact grillage just reaching 40.500 2. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. The assumptions made in estimating unit costs include:  impact of historic project risks are captured by out-turn unit costs 7 This shows the effect of refurbishing 350 grillages each year of the worst-condition grillages. FOUNDATIONS . GRILLAGES AT OR BELOW CA 40 CA 31-40 CA 0-30 3. To complete approximately 400 grillages each year will cost an estimated $10.500 3. due to the heightened risk of them failing. All rights reserved. the average unit cost of a grillage encasement is $25.000 500 0 12/13 13/14 14/15 15/16 16/17 17/18 18/19 19/20 7 Figure 11: Grillage Asset Health Forecast Figure 12 shows the effect of the programme on foundation asset health contrasted with the situation if the grillage encasement programme is not undertaken. Page 30 of 58 .000 2.DO NOTHING) 12+ YRS (91%) 12+ YRS (79%) 7-12 YRS (5%) 7-12 YRS (5%) 2-7 YRS (4%) 2-7 YRS (4%) 0-2 YRS (0%) 0-2 YRS (2%) NOW DUE (0%) NOW DUE (10%) Figure 12: Foundation Asset Health Forecast Programme cost Cost and scope estimation for grillage refurbishment works is an example of volumetric forecasting (see Planning Lifecycle and subsection 4. TL Foundations Fleet Strategy TP.PLAN) (19/20 .000.FL 01.4 for further details).ASSET HEALTH (19/20 . which balances condition and criticality.02 Issue 1 October 2013 Grillage prioritisation Prioritisation will be based on the priority matrix (see Figure 8).000 1. Impact of refurbishment programme Figure 11 shows the predicted impact of the encasement programme on the number of at- risk grillage foundations.2m.1.

4. with the number each year being somewhat dependent on natural environmental events. The plan is to annually investigate foundations at 40 towers and strengthen an average of 8 each year over the RCP2 period.FL 01. TL Foundations Fleet Strategy TP. All rights reserved. Pile foundation replacement generally focuses on sites susceptible to erosion (where the land is unstable).1. Page 31 of 58 .000. The cost of pile foundation strengthening has been derived using our approach to volumetric forecasting. This work is required to support safety and reliability by preventing structure collapses due to foundation failures.4. leading to occasional installation of undersize foundations.000 (including design). and those in rivers which have degraded to a point where replacement is warranted. which is discussed in subsection 4.000 to $170.000 at each site. from $25. with some 20% later being strengthened. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. an average of five pile foundations each year have required replacement.000 has been allowed for each year from 2015 to 2020 for strengthening undersized pile foundations. Costs to strengthen concrete foundations vary considerably. Studies have revealed that concrete foundations built before 1983 were usually designed based on very limited soil testing and often assumed soil properties. again resulting in approximately 20% being strengthened. this equates to a total cost of $2. which is discussed in subsection 4. Over the past 10 years. The cost of pile foundations are derived using our volumetric forecasting methodology.1. with an average cost of $105. An annual cost of $880. We will continue to investigate the capacity of existing foundations at critical sites and will strengthen those found to be understrength. Replace/Refurbish Pile Foundations Replace or refurbish pile foundations based on condition. Similar investigations have been carried out in recent years. Based on 47 pile foundation replacements over RCP2. Pile foundation replacements for RCP2 are forecast at approximately 9 structures per year addressing condition based replacements and new installations in flood prone river locations. Urban developments and changing land use continue to increase the safety criticality of numerous sites each year.02 Issue 1 October 2013  the building blocks used are sufficiently detailed to reflect typical projects  the proportion of sites with difficult soil conditions will tend toward a constant proportion  the proportion of cost incurred due to access and site topography will tend toward a constant proportion. The average out-turn cost for each foundation replacement is $47.2m. In the 1990s several hundred safety critical sites were investigated. Undersized foundation strengthening Strengthen undersized foundations in all critical locations to minimise the risk of tower failure due to overloading.

Planning of all foundation works takes into consideration relevant site strategies. Access routes must be maintained so that.FL 01. Prioritise foundation works Prioritise the refurbishment and strengthening of foundations taking into account existing condition. 4. Our technical standards for bridges rely on the Transit NZ Bridge Manual.0m. Page 32 of 58 . asset criticality and other factors. The landowners requirements for access and load-bearing capability may be significantly less than ours. and existing bridges may need to be upgraded or replaced to meet our requirements.1. We have adopted a risk-based prioritisation approach that takes into account four factors to prioritise foundation works:  condition (taking due account of any known discrepancies between grillage and interface condition)  asset criticality (in respect to Grid reliability and safety)  existing foundation capacity and whether the foundation should be strengthened  whether other works are required on the same property (minimise landowner disruption).02 Issue 1 October 2013 Bridge replacements Replace access corridor bridges based on condition. This is particularly the case where the capacity of an existing bridge is a potential constraint on project works such as grillage replacements or conductor stringing. All rights reserved. we estimate a total expenditure of $6. The main purpose of this strategy is to ensure continuing safe and efficient access to transmission lines for maintenance and project works.0m and this is predicted to continue through RCP2. This optimisation approach seeks to ensure that works are deliverable and undertaken in an efficient and timely manner. the access tracks and bridges can safely support access using conventional 4WD vehicles. TL Foundations Fleet Strategy TP. Based on a forecast of 64 bridge replacements over RCP2. as a minimum. Well maintained access tracks and bridges are essential to allow safe access to transmission line assets when responding to faults or performing routine inspections and maintenance. minimisation of required outages and resources. and any potential synergies with other projects. The average annual expenditure on access track bridge replacements over the last five years is approximately $1. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. with the scope and cost estimates becoming more accurate as the project becomes more refined. The IWP process integrates capex across a moving window of up to 10 years in the future.3 Integrated Works Planning Our capital governance process –IWP – includes the creation of business cases that track capital projects through three approval gates.

cost estimates for foundation works were developed using proprietary systems. It ensures that all re-conductored lines and structure foundations on uprated lines where loads are increased comply with current loading and capacity requirements.2 for further details on how this is applied to replacement projects. equivalent historic projects. Cost estimates for volumetric capital projects are developed on the basis of tailored ‘building blocks’ informed by actual cost of completed.FL 01. which uses the cost estimation tool Transpower Enterprise Estimation System (TEES). All rights reserved. 4. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. They are categorised as volumetric works for estimation purposes. This feedback-based process is used to derive average unit costs for future works. Page 33 of 58 .1.1. This strategy supports delivery of enhancement and development projects discussed in subsection 4.1. P50 is an estimate of the project cost based on a 50% probability that the cost will not be exceeded.02 Issue 1 October 2013 Re-assess foundation requirements before re-conductoring or uprating Ensure any work that changes loadings on structures includes a robust design assessment of the foundation strength to ensure compliance with current standards. Further details on our cost estimation approach can be found in the Planning Lifecycle Strategy document.1. This enhances safety and reliability. Assumptions made in using a volumetric costs methodology to achieve P50 include:  the sample size of historic works is sufficiently large to provide a symmetric distribution for the cost  a large number of equivalent projects will be undertaken in future  cost building blocks based on historic out-turn costs capture the impact of past risks  volumetric estimates are to be determined using the Transpower Enterprise Estimation System (TEES) (US Cost) system  scope is reasonably well defined and reflects a predetermined list of ‘standard building blocks applied to all estimates. the P50 estimate is based upon an equal chance of project overruns or under runs up to the finalisation of the project scope. that is. the expected cost of a programme of similar projects is of more interest than the costs of projects that are estimated separately. In a general sense. Ensure foundation works are scoped to achieve P50 Ensure foundation project estimates are developed and scoped to achieve P50 cost value.4 Cost Estimation Cost estimation is a key stage of the capital investment process and forms a critical input into projects at various stages in the planning process. TL Foundations Fleet Strategy TP. See subsection 4. Historically. The P50 cost value is an estimate of the project cost based on a 50% probability that the cost will not be exceeded. This has now transitioned to the central cost estimation team. Most foundation works are repetitive with similar scopes.

FL 01.DL 12. Capex projects move into the Delivery Lifecycle. This is in line with standard international practice. 4.2. as little more time is required to dig a bigger hole. Procurement issues relevant to the foundations fleet during the RCP2 period are set out below. Page 34 of 58 .1. a standard grillage or other foundation type may be considered. the design process8 aims to ensure appropriate site-specific designs are used. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.02 Issue 1 October 2013 4.2 Procurement For more details of our general approach to procurement. Supply & Contracts Approach (2011) and the Delivery Lifecycle Strategy. 8 While design activities are undertaken during the Planning Lifecycle. Replacement foundation design Design replacement foundations to carry the anticipated design loads of likely future upgrades. see The Sourcing.2. concrete plugs with cast-in tower leg stubs are the preferred method for new foundations. As discussed above in subsection 4. Delivery activities undertaken are described in detail in the Delivery Lifecycle Strategy.1 Design When applied to foundations. All rights reserved. For the grillage replacement option. 4. but.2 Delivery Once planning activities are completed. the only additional cost is for extra concrete. Our transmission line loading standard (TP. Where concrete is not easily transportable to a particularly remote location. slightly longer grillage members are required. For concrete encasement. the majority of detailed design takes place as part of the delivery cycle. TL Foundations Fleet Strategy TP. the installation cost is relatively constant. The following discussion focuses on delivery issues that are specific to the foundations fleet. Foundation design Ensure assets with high safety or Grid criticality are designed and maintained to be more reliable than less critical assets.2. sustainable asset management planning and delivers on the objectives relating to network and cost performance. Designing replacement foundations taking into account anticipated design loads of likely future upgrades is prudent. again.01) specifies higher-return period weather events for critical assets than for less critical ones (such as higher reliability level for more critical assets). There are significant economies of scale in increasing foundation capacity at the same time as undertaking foundation encasement/replacement.

This subsection sets out how IWP is applied to tower and pole project delivery. labour and material constraints. The preferred procurement method is sole source. Operational activities undertaken are described in detail in the Operations Lifecycle Strategy. and second preference.02 Issue 1 October 2013 Award contractor work on a sole source ‘yours to lose’ basis. Award contractor work by geographic locations on a sole source ‘yours to lose’ basis.FL 01. Selected projects are put out to tender based on the availability of the expertise required to perform the project. This strategy aligns with the objective to control costs by minimising supplier diversity. 4. This strategy aligns with the objectives in relation to cost optimisation and system performance and reliability. landowner disruption and system outages are minimised. Foundation work is mostly of a volumetric nature. 4. The following discussion focuses on operational issues that are specific to the foundations fleet. This strategy aligns with the objective to minimise system disruptions and maintain reliability.3 Delivery Planning The plan for delivering new foundations for new transmission lines and upgraded transmission lines are managed under our IWP process as set out in subsection 4. In particular. Project deliverability Ensure planned projects are deliverable within available financial.1. ensuring deliverability of projects planned in line with the IWP processes is essential to support our objectives of controlling costs and achieving the desired asset management outcomes. Locally based contractors have geographic knowledge of the area and so are more suitable to work in rugged terrain. Package work Package works into blocks of consecutive structures and ensure multiple works are carried out at one site simultaneously wherever possible. Where practicable. Page 35 of 58 . Under the IWP processes. TL Foundations Fleet Strategy TP.3 Operations The Operations Lifecycle phase for asset management relates to planning and real time functions. selected tender. Our IWP processes deliver on this strategy.3. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. an integrated programme view is taken rather than evaluating the sum of the individual works. All rights reserved.2. work is packaged to maximise efficiency and ensure that any travel time. Performance-based contracting will be used to provide incentives to contractors to align their objectives with ours.

we employ the following contingency strategies. This strategy aligns with the stakeholder and network performance objectives. When works do require an outage. located in many different environments.  Emergency Management Team: Maintain readiness of emergency management team with communications routes to Civil Defence and to site works contractors. skilled manpower and emergency spares in place to enable rapid restoration of transmission service following single or multiple structure failure(s) or conductor drop(s).  Emergency Restoration Team and emergency spares: Maintain readiness of emergency restoration team and structures – ability to temporarily restore a localised failure (up to 5 towers or 2 km) of any one line (double or single circuit) within 10 days where physical Grid redundancy is not available. it is inevitable that foundations and their towers will occasionally fail during extreme events such as high winds. To ensure rapid network restoration times. This strategy delivers on the objectives in relation to System Performance and Reliability. TL Foundations Fleet Strategy TP. and replacements must be planned to minimise disruption to customers. Planning for failures is essential so that service can be restored relatively quickly when failure occurs. and put in place as required. including emergency restoration structures. Yearly drill for significant outage communications and process.3.FL 01. Continue the business continuity plan. we coordinate with stakeholders to ensure that any unavoidable system disruptions and outages are notified well in advance so that affected parties can prepare. All rights reserved. but may ask others for help following multiple structure failures. Maintain contingency response resources Have sufficient plans. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Very few foundation works require outages. Resources must be sufficient to manage contingencies using a tiered response where local contractors rectify failures of one or two structures.3.  Business continuity plan: Maintain the business continuity plan. floods and landslides. We ensure that asset specific emergency plans are developed for critical assets.1 Outage Planning Power system outages for preventive maintenance. Grid operations identify requirements for outages (including reclose blocks) and manage the planning of outages and reclose blocks. We will follow the strategies set out below when planning outages for foundation assets. including emergency restoration structures. Page 36 of 58 .02 Issue 1 October 2013 4. Foundation works outage planning Plan to minimise disruption to customers for foundation works that require outages. 4.2 Contingency Planning With thousands of towers on the network. corrective maintenance.

1 Preventive Maintenance Preventive maintenance is work undertaken on a scheduled basis to ensure the continued safety and integrity of assets and to compile condition information for subsequent analysis and planning. Maintenance tasks are classed into three categories:  preventive maintenance . Being the most common physical interaction with assets. For the foundations fleet. Page 37 of 58 . mostly because there are no moving parts. 4.4 Maintenance We and our service providers carry out ongoing works to maintain assets in an appropriate condition and to ensure that they operate as required. The following discussion focuses on maintenance issues that are specific to the foundations fleet. servicing  corrective maintenance . TL Foundations Fleet Strategy TP.  Servicing: routine tasks performed on the asset to ensure asset condition is maintained at an acceptable level. fault response . condition assessments . so it is important in terms of providing feedback of information into the overall asset management system. the largest component of preventive maintenance is condition assessment. assess fitness for service. All rights reserved.FL 01. it is also a potential source of safety incidents and human error. The main activities undertaken are listed below.4. These activities and associated strategies are discussed in the following sections. including specific maintenance projects planned for RCP2.  Condition Assessments: activities performed to monitor asset condition or predict the remaining life of the asset. and identify follow up work. repairs  maintenance projects.  Inspections: non-intrusive checks to confirm safety and integrity of assets. We intend to implement the following two preventive maintenance processes on the foundations fleet in support of our objectives stated in chapter 3.02 Issue 1 October 2013 4. Condition assessments are very important because of their role in planning replacement and refurbishment to prevent foundation failures. Our approach to Maintenance and the activities it undertakes are described in detail in the Maintenance Lifecycle Strategy. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Preventive maintenance is generally our most regular asset intervention. as little servicing is required.

based asset management information system. The programme provides a basis upon which replacement or maintenance options can be investigated. prevent imminent failure and address defects. A ground- based patrol visits each structure foundation to identify any defects that could pose a risk to the structure integrity.4. The frequency of patrols will be assessed based on site or corridor safety criticality. The condition assessment (CA) programme monitors and records the condition of transmission line structures. conductors and hardware.FL 01. Line patrols are generally performed once a year on every transmission line asset. All CA data is currently stored in our maintenance management system MMS. New foundation assets are first assessed just prior to expiration of the defects liability period.2 Corrective Maintenance Corrective maintenance includes unforeseen activities to restore an asset to service. TL Foundations Fleet Strategy TP. condition assessments are carried out on a cyclic basis and entail a detailed inspection of the structure and span. make it safe or secure. It also allows extrapolation of the assessed condition into the future. When significant defects are identified a maintenance job is raised to rectify the issue. We will continue to develop and refine the existing condition assessment process to ensure relevant. All rights reserved. Sites with unusually rapid degradation or those with higher criticality may be assessed more frequently. At June 2013.17B Transmission line condition assessment Part B: Structures. As discussed in 2. Foundation condition assessments Carry out regular foundation condition assessments. and enables planning to take into account the impact of varying environmental ageing factors. 4. however this is being replaced with a MAXIMO. By the end of 2013 all CA data will be on the MAXIMO system.2. Condition assessment is carried out in line with TP. nationally consistent.02 Issue 1 October 2013 Perform regular patrols Carry out regular patrols to allow the planning of work required to mitigate or avoid any failure risks. This strategy supports the network performance objectives for foundation assets. high-quality data is collected to inform asset planning and decision making. the assessment frequency is reduced to 4 years.3. foundations. If the condition assessment score is less than 50. It includes the required follow- up action. Such defects include:  severely damaged foundations  geotechnical risks due to slips. scouring and subsidence  third party excavation or construction around tower foundations. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. 5%–10% of individual towers and pole structures are on partial (half cycle) assessments. even if this is scheduled some time after the initial need for action is identified. Thereafter. tower line assets are generally assessed every 8 years. The assessment produces a condition assessment score for various components and a defect list. which is expected to provide clearer reporting of data and trends.SS 02. Page 38 of 58 .

FL 01. a Maintenance Project will be instigated to undertake the repairs works. Corrective maintenance has historically been categorised as repairs and fault (response) activities. improve redundancy and remove system constraints by maximising the availability of assets. it is critical that this be established as quickly as possible. including urgent dispatch to collect more information  Repairs: unforeseen tasks necessary to repair damage. Page 39 of 58 .02 Issue 1 October 2013 These jobs are identified as a result of a fault or in the course of preventive work such as inspections. Slope stability and waterway protection works and minor repairs Complete slope stability and waterway protection works and minor foundation repairs at structures where specific defects need repair. When the cause is determined. Activities include:  Fault restoration: unscheduled work in response to repair a fault in equipment that has safety. repairs are planned and implemented commensurate with the safety risk and asset criticality. environmental or operational implications. This supports our network performance and safety objectives. Corrective works may be urgent and if not completed for a prolonged period. Respond to foundation failures in a timely manner Ensure Lines Maintenance contractors have staff patrolling the asset within one hour of being notified of a fault and can respond to two faults at the same time. The purpose of a fault patrol is to establish if the circuit can be safely re-energised and determine the cause of the fault. For the purposes of system performance and safety.9 Timely repairs reduce the risk of failure. Repairs include the correction of defects identified during preventive maintenance and other additional predictive works driven by known model type issues and investigations. TL Foundations Fleet Strategy TP. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Repairs We may repair foundations where a fault has been identified that could potentially result in a failure or when a failure has occurred. In both cases the repairs are carried out to support the safety and network performance objectives. reduced network reliability may result. See the strategy Maintain Contingency Response Resources for details on how we will manage the response of contractors to faults. prevent failure or rapid degradation of equipment  Reactive inspections: patrols or inspections used to check for public safety risks or conditions not directly related to the fault in the event of failure Fault Response Fault response is required to restore the function of assets as quickly as possible to maintain supply to customers. All rights reserved. 9 Where the number of potential repairs is deemed sufficiently high.

3). as such. Refurbishment by blasting and painting has proven highly successful.02 Issue 1 October 2013 Works covered by this strategy include:  river diversion or bed protection works  checking/repairing splice and anchor bolts  baseplate/ground connection maintenance and repair where scope is sufficiently small that a maintenance project is not raised  re-forming ground where water pooling around tower bases  works associated rectifying ground subsidence or movement  rectifying damage caused by vehicle or farm activity.3 Maintenance Projects As discussed in subsection 2. anchor bolts and cast-in stubs at a condition assessment score of 50 prior to onset of significant rusting. The drivers for maintenance projects include asset condition.  Cast-in in-situ stub leg: There are often rust issues at the concrete interface (ringbark corrosion). those with baseplates and anchor bolts and those with cast in stubs.4.  Baseplate /anchor bolt: Poor-quality dry-pack mortar originally used under baseplate. Over the RCP2 period we intend to implement the following maintenance projects on the foundations fleet.type foundations is porous and has led to mortar crumbling. The typical threshold score of 50 before any significant rusting or loss of section is visible. Refurbishment selection is based on the minimum condition assessment score of the four leg-based scores collected at each site. their refurbishment is considered a maintenance project activity.2. Maintenance jobs are typically run as a project where there are operational and financial efficiencies from doing so.300 baseplate connections currently have a condition assessment score less than 50 (see subsection 2. and to improve performance. Maintenance projects would not be expected to increase the original design life of the larger assets. Some 1.5. In extreme TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. The purpose of this strategy is to ensure the integrity of the foundation system is maintained and lifecycle costs are minimised. Moisture ingress under the baseplate has subsequently led to corrosion of the anchor bolts and baseplate (which is not visible until the grout is removed during refurbishment). All are subject to corrosion.2. Foundation connection components comprise two types. 4. but they typically do not extend far into the concrete (<20mm). Foundation components are considered a relatively minor part of the overall foundation and tower structure and. TL Foundations Fleet Strategy TP. mitigating safety and environmental risks.FL 01. All rights reserved. Regardless. their failure has the potential to result in a structure collapse with significant implications for safety and reliability. We periodically review refurbishment criteria and designs to ensure appropriate practice is being employed. Connection component refurbishments Refurbish corroding baseplates. maintenance projects typically consist of relatively high- value planned repairs or replacements of components of larger assets. Page 40 of 58 .

this equates to an annual expenditure of $3.02 Issue 1 October 2013 cases a small area of concrete is broken out. Once refurbished. We plan to complete river protection work on existing pole foundations where river erosion poses a significant threat to security of supply on the Grid.000.000.2. All rights reserved. This work has an estimated cost of $600. This equates to an annual average expenditure of $260. discussed in subsection 4.3). At 360 and 270 sites respectively. Page 41 of 58 . The total expenditure for this strategy is $1. We plan to carry out an ongoing connection refurbishment programme of approximately 630 sites each year throughout RCP2 – 360 baseplates and 270 cast-in in-situ legs. Waterway protection works Complete waterway protection work on defective pole foundations in riverbeds. which equates to an annual average expenditure of $200. We plan to complete the programme of refurbishing existing foundations at sites where failure would pose significant risk to people. Refurbishment selection is based on the minimum condition assessment score of the four leg-based codes collected at each site.0m. Average out-turn costs for baseplate and anchor bolt refurbishments are $7. The cost of these refurbishments is derived in line with our volumetric forecasting methodology. TL Foundations Fleet Strategy TP.4.5m.000 for each tower.1.3m over RCP2. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Foundation works are planned to protect these foundations from chloride ingress during RCP2. Transmission line tower foundations are occasionally located in marine environments. Some 670 stub connections currently have a condition assessment score less than 50 (see subsection 2. Marine foundation refurbishment Refurbish specific foundations in marine environments.900. We have 8 towers in a marine environment on the Tiwai causeway supporting the 2 transmission lines that supply Tiwai point. these connections will require periodic paint maintenance at a repeat cycle of between 12 and 20 years depending on the site environment. property or the Grid. they are subject to additional degradation from tidal activity and chloride ingress attacking the reinforcing steel.000. The work is planned for 38 sites on three South Island assets: AHA-OTI-A. This is based on existing condition assessment information and expected degradation.FL 01.000 – an average of $75. The estimated cost of this work is $700. and the area repaired by grouting. Estimated costs over RCP2 are $1. The typical threshold is condition assessment 50 before any significant rusting or loss of section is visible.300 for cast-in in-situ leg refurbishments. As a result of this location. we will also complete the marine foundation refurbishment works on the HEN- OTA-A line that began in RCP1. the steel cleaned. DOB-TEE-A and BLN-KIK-A. During RCP2. and are $2.

Site reinstatement Reinstate decommissioned site foundations to their former natural forms.1 Disposal The Disposal Lifecycle eventuates when foundations are no longer needed or when a foundation has degraded to an extent where refurbishing is uneconomic. We are continuing with the transfer of a number of assets at the fringes of the existing Grid to our distribution business customers.5 Disposal and Divestment The disposal and divestment phase includes the process from when planning of disposal of an asset begins through to when the asset is no longer owned by us.FL 01. We will monitor rehabilitated areas for a period of time after re-instatement. we will follow appropriate decommissioning process. This information is fed into the management of the entire foundation asset fleet. recovery and recycling/disposal of materials. The total number of assets to be transferred represents 4% of the total tower and 9% of the total pole fleet as at June 2013. This subsection describes our approach to the disposal of assets within the foundations fleet. The approach is set out in detail in the Disposal Lifecycle Strategy. 4. Page 42 of 58 . Refer to the Towers and Poles Fleet Strategy for the number of towers and poles likely to be transferred to customers between 2013/14 and 2019/20. In the case of a failure. Foundation divestment Divest foundations as part of transmission line divestments to customers.5. tested and operated to high standards of skill.5. including requirements for foundation removal. All rights reserved. yet there are important requirements for the disposal phase. TL Foundations Fleet Strategy TP. 4. although we must also remain cognisant of any safety and environmental issues and technical impacts on the Grid such as a change in constraints and flexibility of Grid operation. This process and its justification are described fully in the Disposal and Divestment Lifecycle Strategy. This includes all divestments that we believe have a 50% or greater likelihood of occurring during the timeframe. Foundations may be replaced with new ones. professionalism and safety. 4.2 Divestment Implementation of divestment is primarily the change of ownership. Decommissioned site foundations should be re-instated to their former natural forms to allow the land to recover. we carry out diagnostic inspection and testing to investigate the cause of the failure.02 Issue 1 October 2013 4. All towers will have associated foundations and these will be divested with the tower structure. Consistent with environmental objectives.6 Capability We require grid assets and equipment to be maintained. Work is to be carried out only by individuals TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.

improved guidelines will be developed including more photographic examples where relevant. This helps to prevent injury to workers and damage to assets.FL 01. Page 43 of 58 . TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Data must include details of exactly what is installed.SS 06. moisture contents. and TP. We plan to enhance the failure and incidence records system to improve consistency and usefulness of the data. particularly for grillages. 4. The current project to transition to the MAXIMO-based asset management information system will include a review and cleansing of data. Use these costs in the economic modelling along with degradation rates and AHI to define least lifecycle cost options for programmes of work. design reports. To improve condition assessment consistency. Comprehensive records that cover the original installation of a foundation structure and any subsequent modifications are vital to enable quality asset management decisions. Maintain and develop fleet strategies Maintain and develop the fleet strategy for the foundation fleet. Quality condition data is also required. some fields are currently incomplete. This section describes the approach used to ensure that these competencies are present in those undertaking work on the foundation and access assets. All rights reserved. condition data and investigation reports. land use etc. The capability strategies are described under three headings:  Asset Knowledge  Risk Management  Training and Competence. While good asset attribute and condition data is available for most foundation sites. including root cause analysis. Maintain up-to-date asset records Maintain up-to-date records of all foundation asset attributes. Data quality and completeness will continually be reviewed and amended as required to ensure a high-quality dataset is maintained. condition and performance. Continue the development and refinement of models to predict the asset health of foundations. type test reports.25 Minimum Requirements for Transpower field Work). TL Foundations Fleet Strategy TP.1 Asset Knowledge Robust asset knowledge is critical to good decision making for asset management.20 Minimum Competencies for Line Maintenance.6. and to protect the public and their property from harm.SS 06. Ensure the modelling includes lessons learned from the refurbishment programme in relation to observed degradation in various soil types. Revise building blocks on an ongoing basis using costs from completed works and forecast innovations and improvements.02 Issue 1 October 2013 with competencies that are both appropriate and current (see TP.

As outlined in subsection 2.6. Foundation worker competencies Adhere to the following service specifications.6. TL Foundations Fleet Strategy TP.2 Risk Management Our approach to risk management is central to our decision making as we seek to achieve our overall asset management objectives and optimise the timing of major investments. particularly given the consequences of foundation failure on transmission line performance. The risk model will specifically consider uncertainty in the inputs to risk-based decision making. we apply an adaptive condition assessment approach where the frequency and extent of condition assessment interventions is determined based on the most recent condition assessment and the predicted current state.SS 06.3 Training and Competence We have two service specifications that define the competency requirements for working on transmission line assets. including foundations:  TP.SS 06.SS 06. 4.FL 01.20 Minimum competencies for lines maintenance  TP.20 (Minimum competencies for lines maintenance) and TP. Knowledge of foundation condition is crucial to the assessment of options for foundation replacement and refurbishment. We maintain a minimum baseline of retained skilled workforce: engineers and site works operators who understand the physical assets. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. TP. All workers must hold appropriate competencies to work on our assets in line with the service specifications.25 Minimum requirements for Transpower field work. In recognition of this. We will ensure more robust and detailed development of scope for major replacements to improve the accuracy of cost estimates and the validity of the economic analysis of options. Risk-based options evaluation framework Develop a risk-based framework and associated tools for evaluating foundation investments. All rights reserved. The key parts of this framework will be tools for making quantitative estimates of the likely impacts of foundation failures on service performance and safety on a span-by-span basis. Page 44 of 58 .2. We will develop an improved risk management framework and tools that can be used across the foundations fleet to evaluate investment options. Understanding and modelling uncertainty then becomes an increasingly important element in risk management decision making.3. and will allow risk assessments to be more readily communicated to internal and external stakeholders. we are developing asset health and criticality frameworks to improve and integrate our risk-based asset management.02 Issue 1 October 2013 4.25 (Minimum requirements for Transpower field work). The strategies below discuss how we plan to progress this in regards to the foundations fleet. Risk management processes will be made more robust and systematic.SS 06.

all grillages that currently have a condition assessment score less than 30. P50 is an estimate of the project cost based on a 50% probability that the cost will not be exceeded.02 Issue 1 October 2013 Since 2011. asset criticality and other factors. Integrated Ensure any work that changes loadings on structures includes a robust design assessment of the Works Planning foundation strength to ensure compliance with current standards. Contingency Have sufficient plans. including strengthening and relocation. Asset management competency Increase and then maintain the in-house skill base with regard to Asset Management. TL Foundations Fleet Strategy TP. Replacement and Strengthen undersized foundations in all critical locations to minimise the risk of tower failure due to overloading. Design replacement foundations to carry the anticipated design loads of likely future upgrades. Replace access corridor bridges based on condition. Development Use concrete encasement designs as the preferred refurbishment option wherever they can be installed in a cost effective manner. much of the training has been provided to service providers at no cost (other than the employee’s time). By the end of the RCP2 period. Page 45 of 58 . Prioritise the refurbishment and strengthening of foundations taking into account existing condition. preferably by concrete encasement. To ensure better long-term asset management outcomes. We plan to continue with this training strategy.FL 01. This has resulted in a considerable increase in service provider training. Planning Enhancement and Modify existing foundations.7 Summary of RCP2 Fleet Strategies Our asset management plans for the fleet of foundation assets for each lifecycle stage are summarised in the table below. 4. Delivery Ensure assets with high safety or Grid criticality are designed and maintained to be more reliable Design than less critical assets. refurbish. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. we plan to increase the emphasis on training in Asset Management principles and application across all relevant parts of the business. All rights reserved. to support new structures or to enable upgrading of conductors. Procurement Award contractor work by geographic locations on a sole source ‘yours to lose’ basis. Cost Estimation Ensure foundation project estimates are developed and scoped to achieve P50 cost value. Refurbishment Replace or refurbish pile foundations based on condition. Ensure no grillage foundation has a condition assessment score less than 40 by 2033 (in 20 years). Operations Outage Planning Plan to minimise disruption to customers for foundation works that require outages. Delivery Planning Package works into blocks of consecutive structures and ensure multiple works are carried out at one site simultaneously wherever possible. labour and material constraints. skilled manpower and emergency spares in place to enable rapid restoration of transmission service following single or multiple structure failure(s) or conductor Planning drop(s). Ensure planned projects are deliverable within available financial.

All rights reserved.25 (Minimum requirements for Transpower field work). Disposal and Divestment Disposal Reinstate decommissioned site foundations to their former natural forms. Knowledge Maintain and develop the fleet strategy for the foundation fleet. Refurbish corroding baseplates. Risk Develop a risk-based framework and associated tools for evaluating foundation investments. TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.20 (Minimum competencies for lines Training and maintenance) and TP.FL 01.SS 06. Ensure Lines Maintenance contractors have staff patrolling the asset within one hour of being Corrective notified of a fault and can respond to two faults at the same time. Complete waterway protection work on defective pole foundations in riverbeds. TP. Page 46 of 58 . Competence Increase and then maintain the in-house skill base with regard to Asset Management.SS 06. Maintenance Projects Refurbish specific foundations in marine environments. Management Adhere to the following service specifications. TL Foundations Fleet Strategy TP. Capability Asset Maintain up-to-date records of all foundation asset attributes. Maintenance Carry out regular foundation condition assessments. Maintenance Complete slope stability and waterway protection works and minor foundation repairs at structures where specific defects need repair.02 Issue 1 October 2013 Maintenance Carry out regular patrols to allow the planning of work required to mitigate or avoid any failure Preventive risks. Divestment Divest foundations as part of transmission line divestments to customers. condition and performance. anchor bolts and cast-in stubs at a condition assessment score of 50 prior to onset of significant rusting.

TL Foundations Fleet Strategy TP.02 Issue 1 October 2013 Appendices TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. All rights reserved. .FL 01.

02 Issue 1 October 2013 A GRILLAGE EXAMPLES Figure 13 shows a cross section of a grillage foundation.FL 01. All rights reserved. Figure 14 shows grillages at a condition assessment score of 20. Appendices | page 48 . Ground line interface Grillage Figure 13: Cross section of a grillage foundation  The picture above shows a grillage foundation and the areas we assess to determine the condition score (condition assessment score).  The grillage condition score represents the worst of the steel found from 300mm below the ground line to the base of the grillage.  The grillage condition assessment degrades from a score of 100 to 0. where a score of 40 means the galvanising is gone and rust is beginning to pit the steel. TL Foundations Fleet Strategy TP. Figure 14: Grillages at a condition assessment score of 20 TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. The ground-line interface condition represents the worst of the steel found from 100mm above the ground line to 300mm below the ground line. (CA code). and a score of 20 means there has been 10% loss of metal cross section and replacement is required.

TL Foundations Fleet Strategy TP. All rights reserved.FL 01. Appendices | page 49 . Figure 15: Grillages at a condition assessment score of 40 TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.02 Issue 1 October 2013 Figure 15 shows grillages at a condition assessment score of 40.

correctly backfilled and compacted as is standard. 10 Rusting exceeds R/C. now visible at the surface. and some loss of cross section. 30 Flaking rust. 80 New galvanised steel leg without added protective coating. heavy flaking rust. 60 Speckled rust. foundation failure probable under ‘everyday conditions’. with added protective 100 coating in as-new condition). All rights reserved. 0 Metal loss serious. Condition Guidelines Assessment 100 New steel grillage fully galvanised. 50 Steel rust stained at ground level and just below the surface. 90 Surface is dulled to a light grey colouring. 60 Start of steel member surface rusting. 70 Bolts beginning to rust beneath the surface. Table 5: Grillage Foundation Connection (Buried Grillage – soil/main leg interface) Condition Assessment Guidelines TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Severe rusting of steel about ground line and below. 50 Steel surfaces below ground beginning to develop rust spotting. but tower not significantly at risk. 40 Rust beginning to pit steel below ground line (GL) advancing up main leg member. Table 5 shows grillage foundation connection (buried grillage – soil/main leg interface) condition assessment guidelines. Complete breakdown of nuts and bolt heads.02 Issue 1 October 2013 B FOUNDATION CONDITION CODES Table 4 shows the grillage foundation condition assessment guidelines. 70 Protective coating failing. Patches of galvanising gone. 90 Protective coating 50% of way to failure. pitting and nodules of rust appearing on steel surfaces at ground line and 40 below. 80 Older grillage (now fitted with cathodic protection (C/P)) otherwise in condition score of 50-60. but tower not significantly at risk. C/P no longer effective and foundation deteriorating. black underneath 20 (R/C) with loss of metal cross-sectional area of approximately 10%.FL 01. 10 Metal loss exceeds replacement criteria. galvanised and free of damage. 30 Flaking rust on main leg section of grillage just below GL. 20 (Replacement Metal loss on main and/or bracing steel reaches replacement criteria (10% loss of criteria R/C) cross section). Appendices | page 50 . Loss of metal. TL Foundations Fleet Strategy TP. Table 4: Grillage Foundation Condition Assessment Guidelines Condition Guidelines Assessment New (or refurbished steel members. 0 Serious risk of tower leg tension/compression failure.

increased rust staining. without obvious deterioration. Minor spalling off the cap. Minor spalling to 20 (R/C) concrete as rust penetrates beneath the concrete surface. and no longer able to reliably sustain ultimate site- 20 (R/C) specific design loads with reliability. Table 7: Foundation Connection (cast-in-situ steel stubs/concrete interface) Condition Assessment Guidelines TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. 90 At least 5 years of service. but less than 40%. 50 Spiral reinforcing in some areas corroding. causing serious spalling/cracking etc. concrete darkening and surface roughening. Galvanising on leg dulled. 80 Reinforcing exposed to soil severely corroded. major spalling off the cap. 30 5% metal loss on leg /concrete interface surface. Galvanised leg section is free of damage. 70 Protective paint depleted. 90 Foundation in service at least 10 years. Foundation severely cracked unable to sustain design loads. 40 Main vertical reinforcing start corroding. but no visible deterioration.02 Issue 1 October 2013 Table 6 shows the concrete foundation condition assessment guidelines. Appendices | page 51 . with associated underground cracking/spalling. heavy staining around leg. is protectively painted 300mm 100 either side of concrete surface level. Expansion cracks in cap. TL Foundations Fleet Strategy TP. Flaking rust and loss of metal cross section of 10% at concrete level. 40 Rust pitting at concrete/steel interface. in good condition. 60 Specks of rust appearing at concrete steel interface. Condition Guidelines Assessment 100 New foundation. 50 Loss of galvanising from interface/leg surface. due to crumbling of concrete mass and/or corrosion of the reinforcing. 0 Metal loss exceeds 40%. 0 Uplift failure possible under ‘everyday conditions’. Foundation at replacement criteria. but not at immediate risk of 10 failure. 10 Metal loss exceeds 20%. Table 7 shows the foundation connection (cast-in in-situ steel stubs/concrete interface) condition assessment guidelines. 60 Embedded reinforcing cage rusting. All rights reserved.FL 01. 30 Main reinforcing seriously corroded. Table 6: Concrete Foundation Condition Assessment Guidelines Condition Guidelines Assessment New foundation. 70 Exposed reinforcing. Protective paint at 80 concrete level showing signs of peeling or wear. minor rust.

Table 8: Foundation Connection (anchor bolts and baseplate /mortar and concrete Interface) condition assessment Guidelines TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. Rusting of bolt threads and 30 nuts below the baseplate.02 Issue 1 October 2013 Table 8 shows the foundation connection (anchor bolts and baseplate/mortar and concrete interface) condition assessment guidelines. but no loss of steel. 80 Protective coating ineffective.FL 01. New surface protective coating to seal out any water. mortar in good condition. 70 Baseplate and anchor bolt galvanising rough. 40 Mortar crumbling. 50% or more loss of cross section on anchor bolts overall. bolts corroding. TL Foundations Fleet Strategy TP. First speckled rust 50 appearing on anchor bolt threads. but still effective. All rights reserved. Metal loss on anchor bolts which prevents the withstanding of ultimate site-specific design 10 loads. 90 Surface coating deteriorating. Flaking rust to bottom of baseplate. and critical areas discoloured. 20% metal loss on any one bolt and 10% metal loss over all anchor bolts. Condition Guidelines Assessment New or refurbished galvanised steel baseplate onto concrete held anchor bolts. Waterproof 100 mortar packed tightly between baseplate and concrete foundation. 60 First sign of rust staining at edge of baseplate. Chunks of mortar gone exposing significant rusting of 20 (R/C) inner bolts and baseplate /levelling nuts. Appendices | page 52 . Rust staining appearing as a brown/red rim on bottom of baseplate. baseplate surface rust. or serious risk to tower at a less 0 loss level where structure heavily loaded. Significant rusting to bottom of baseplate.

500 3. no grillages with CA less than 30 by 2020. All rights reserved. then continues linearly to forecast future condition. Appendices | page 53 .000 2.1. Encase 300/Year Key points of alternative plan 300/Year:  Target 300 grillage encasements each year. a model has been created to predict current and future grillage condition and asset health.FL 01.02 Issue 1 October 2013 C GRILLAGE ENCASEMENT MODELLING As discussed in sections 2.2 shows the impact on condition if the proposed plan to refurbish 350 of the worst condition tower grillages each year is followed (plus an additional 50 each year which are not in such poor condition. The following two sections show the impact of refurbishing 300 and 200 tower grillages each year. TL Foundations Fleet Strategy TP.1. Figure 16 shows the effect of the encasement plan on grillage condition.2. It assumes a linear degradation rate from the original installation date (at condition assessment 100). to the most recent ground-line condition recording. GRILLAGES AT OR BELOW CA 40 (300/YEAR) CA 31-40 CA 0-30 3.  Plan fails to meet the objectives stated in section 4.500 2.000 500 0 Jun-2013 13/14 14/15 15/16 16/17 17/18 18/19 19/20 Figure 16: At-Risk Grillage Forecast (300 encasements/year) TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.000 1.1.2. that is.4 and 4. Subsection 4.2.  Prioritisation as shown in the matrix in Figure 8.500 1. but where it is prudent to refurbish them at the same time as the others to minimise landowner disruption).

000 2.500 2.500 1.  Prioritisation as shown in the matrix in Figure 8. GRILLAGES AT OR BELOW CA 40 (200/YEAR) CA 31-40 CA 0-30 3.000 500 0 Jun-2013 13/14 14/15 15/16 16/17 17/18 18/19 19/20 Figure 18: ‘At-Risk’ Grillage Forecast (200 encasements/year) TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013.  Plan fails to meet the objectives stated in section 4.ASSET HEALTH (19/20 .1.2.000 1. All rights reserved.FL 01.500 3. no grillages with CA less than 30 by 2020 Figure 18 shows the effect of the encasement plan on grillage condition. FOUNDATIONS . TL Foundations Fleet Strategy TP.02 Issue 1 October 2013 Figure 17 shows the effect of the programme on foundation asset health/remaining life at the end of RCP2. Appendices | page 54 . that is.300/YEAR) 12+ YRS (88%) 7-12 YRS (5%) 2-7 YRS (4%) 0-2 YRS (2%) NOW DUE (1%) Figure 17: Foundation Asset Health Forecast (300 encasements/year) Encase 200/Year Key points of alternative plan 200/Year:  Target 200 grillage encasements each year.

All rights reserved. FOUNDATIONS .200/YEAR) 12+ YRS (85%) 7-12 YRS (5%) 2-7 YRS (4%) 0-2 YRS (2%) NOW DUE (4%) Figure 19: Foundation Asset Health Forecast (200 encasements/year) TL FOUNDATIONS FLEET STRATEGY © Transpower New Zealand Limited 2013. TL Foundations Fleet Strategy TP.02 Issue 1 October 2013 Figure 19 shows the effect of the programme on foundation asset health/remaining life at the end of RCP2. Appendices | page 55 .ASSET HEALTH (19/20 .FL 01.