APA VTS - D3 - Urban encroachment business case review - 20161221 - Public

There are three relevant topics addressed by BCN230: 1 AS2885.1-2012 Section 4.7 Special Provisions for High Consequence Areas makes requirements where there is a change of land use ar

DOCUMENTS

APA Group “Business Case – Capital Expenditure, Encroachment High Consequence” (provided to GPA by e-mail dated 16-12-2016) n/a EPCRC Final Report, Project RP4.21A: Understanding ALARP,

Help or a Distraction In Ensuring Public Safety? APGA Conference,

STANDARDS

AS 2885.1-2012 Pipelines – Gas and liquid petroleum – Part 1: Design and construction

AS 2885.3-2012 Pipelines – Gas and liquid petroleum – Part 3: Operations and Maintenance

ABBREVIATIONS

ALARP As Low As Reasonably Practicable

APGA Australian Pipeline and Gas Association

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EPCRC Energy Pipelines Cooperative Research Centre

MAOP Maximum Allowable Operating Pressure

AS2885, the Australian Standard for Pipelines – Gas and Liquid Petroleum, applies to the Victorian Transmission System Specifically, when land-use changes occur around existing pipelines, the provisions of AS2885.1-2012 – Pipelines – Gas and Liquid Petroleum – Part 1: Design and Construction – apply.

APA Business Case 230 (BCN230) cites the requirements of AS 2885.1-2012 and presents GPA’s assessment of whether the statements about the Australian Standard for high‑pressure gas pipelines are accurate This section outlines GPA’s opinion and the reasoning used to interpret AS 2885.1-2012, with a focus on how the standard governs the design, construction, operation, and safety of high‑pressure gas pipelines in Australia By evaluating the alignment between project claims and the standard, GPA clarifies which provisions are satisfied, which require justification, and how compliance will be demonstrated within the project context.

HIGH CONSEQUENCE AREAS AND CHANGE OF LAND USE

The APA BCN230 discussion is primarily based around the provisions of AS2885.1-2012, Section 4.7

Special Provisions for High Consequence Areas

BCN230, Section 3.1 provides the context and implications of these requirements

Firstly, the requirements for protection measures to be applied to external interference (mechanical damage) threats are briefly explained:

 Protection requirements are based on the location classification of a pipeline, which in turn is determined by the land use within the “measurement length”

 The “measurement length” is calculated on the basis of the maximum allowable operating pressure and diameter of the pipeline

BCN230 then quotes the relevant location class definitions from AS2885.1

BCN230 provides a concise outline of the essential requirements for designing a new pipeline in High Consequence Areas (HCAs), guiding engineers to address safety, integrity, and environmental risk from the outset In AS2885.1, a High Consequence Area is defined as a location where pipeline failure could result in multiple fatalities or significant environmental damage.

Section 4.7.2 No Rupture specifies the location classes where the "no rupture" requirement must be met In AS2885, rupture is defined as a pipe failure that creates a hole whose diameter equals the pipe diameter, leading to maximum energy release and a high risk of casualties if people are nearby BCN230 describes two ways to satisfy the no-rupture criterion: either set a critical defect length that exceeds 150% of the maximum axial defect length, or reduce the pipeline pressure so that the wall stress falls below the nominated threshold; however, in most cases the necessary pressure reduction would significantly compromise gas supply capacity.

Section 4.7.3, the Maximum Discharge Rate, defines the maximum energy release rate allowed by the location class as specified in BCN230; this requirement applies where a pipeline may be punctured but not ruptured, and it is included in AS2885 to limit the consequences of an ignited gas release in areas where people are present.

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Under AS2885, if a pipeline is not designed to the current AS2885.1 standard, or if there is a change of land use along the route, Section 4.7.4 Change of Location Class applies, regardless of whether the pipeline was designed to the current version In such cases, the pipeline must be modified to meet the provisions of Sections 4.7.2 and 4.7.3, or a documented safety assessment must be undertaken to demonstrate that the risk from loss of containment involving rupture is ALARP.

BCN230, Section 5 lists the options to be considered when conducting an assessment for the purposes of AS 2885.1, Section 4.7.4

BCN230, Section 6.2 provides a summary of the foregoing:

AS 2885.1 mandates that for new pipelines, rupture is considered a non-credible risk in high-consequence areas (T1 or T2) Clause 1.4 requires that every existing pipeline be assessed against Clauses 4.7.2 and 4.7.3 to verify compliance If an existing pipeline does not meet either clause, mitigation must be applied in accordance with Clause 4.7.4, regardless of whether there has been a land-use change.

GPA maintains that the BCN230 explanation faithfully reflects the content and intent of the AS2885.1-2012 provisions for High Consequence Areas, and that it is sufficient to support the case as presented By aligning with the standard, BCN230 provides a credible, well-supported basis for the argument and helps decision-makers understand how High Consequence Area requirements are addressed.

RISK ASSESSMENT

BCN230 Section 4 lists the risk rankings for the VTS in 2016 The quoted risk levels are in accordance with the risk ranking provided in the risk matrix in AS2885.1-2012 (Table F4)

To support the statement that intermediate risks are only acceptable if ALARP is demonstrated, BCN230 provides an excerpt from AS2885.1-2012 Table F5—the risk treatment actions table—which specifies the required measures to be applied for the assessed risk level.

GPA maintains that the BCN230 explanation accurately reflects the content and intent of the AS2885.1-2012 provisions governing intermediate risks, and that this explanation is sufficient to support the case as presented.

This Commentary Report does not cover the process by which APA risk assessments were conducted or their conclusions, and the Risk Assessment intended to be included as Appendix A to BCN230 has not been provided to GPA; however, several points should be noted.

Where the consequence assessment concludes that a pipeline failure would be catastrophic—such as resulting in multiple fatalities—the risk matrix in AS2885.1-2012 (Table F4) does not permit a risk ranking lower than Intermediate; therefore, ALARP (as low as reasonably practicable) must be demonstrated to justify accepting the risk.

For the pipelines considered by BCN230, an ignited rupture would expose people within a few hundred metres of the gas release to heat radiation strong enough to cause fatal or life‑threatening injuries In High Consequences Areas, where large numbers of people are likely to be exposed to this radiation, it is reasonable to conclude that a significant public safety risk exists and that robust mitigation measures are necessary.

PENETRATION CALCULATIONS

BCN230 Sections 5.2 (Project 1 – T24 Brooklyn – Corio), 5.3 (Project 2 – T74 Wollert – Wodonga) and 5.4 (Project 3 – T112 Brooklyn – Lara) present penetration calculations for large excavators operating in the vicinity of the nominated pipelines It is not within GPA’s scope to confirm the APA calculations; however, these calculations are understood to be performed in accordance with the AS2885.1 methodology.

Appendix M and APA’s QA processes

To interpret the data in these tables correctly, it is essential to distinguish between the “No rupture” criterion in AS2885.1, Section 4.7.2, and the failure mode assessment that compares the maximum tooth length with the critical defect length (CDL); the CDL ratio—defined as the pipeline CDL divided by the maximum tooth length—serves as the key metric in this comparison.

 Where the maximum defect length exceeds the CDL (i.e “CDL ratio”1) then the pipeline will leak rather than rupture

 Where the maximum defect length is 2/3 of the CDL (i.e “CDL ratio”>1.5) then the “No rupture” criterion in AS2885, Section 4.7.2 is met

The No Rupture criterion, defined as a CDL ratio greater than 1.5, contrasts with the failure‑mode assessment criterion, which uses a CDL ratio greater than 1; both calculations are based on typical excavator tooth geometries described in AS 2885.1 Appendix M, and the 1.5 factor provides a conservative margin to account for the possibility that the actual excavator tooth striking the pipeline may be larger than the standard geometry presented in Appendix M.

Therefore, the information presented in BCN230 should be interpreted as follows:

In a pipeline integrity assessment, when the assessment concludes that the pipeline can be penetrated but the CDL ratio is less than 1.5 (the criterion for “no rupture” in accordance with AS2885.1 Section 4.7.2), the failure mode is presented as Rupture; however, if the CDL ratio lies between 1 and 1.5 the actual failure mode may be Leak or Rupture depending on the geometry of the excavator tooth striking the pipeline, with leakage occurring if the tooth length is shorter than the CDL and rupture becoming more likely as the CDL ratio approaches 1; conversely, when the CDL ratio is less than 1, the failure mode is Rupture.

 Where the assessment concludes that the pipeline can be penetrated but that the CDL ratio exceeds 1.5 then the failure mode is presented as Leak (i.e a hole rather than a rupture)

When the assessment concludes that the pipeline cannot be penetrated (NP = no penetration), the CDL ratio—defined as the pipeline CDL divided by the maximum tooth length—becomes irrelevant to the assessment.

AUSTRALIAN PIPELINE INDUSTRY APPROACH

As discussed in the previous section, where a risk level is determined to be “Intermediate” in accordance with AS2885.1, then ALARP must be demonstrated

AS2885.1 defines ALARP as the situation where the cost of further risk reduction is grossly disproportionate to the benefit gained from the reduced risk that would result This interpretation is based on two UK legal judgments from the late 1940s and early 1950s The Standard also provides general, non-mandatory guidance in Appendix G.

Appendix G of AS2885.1 provides no detailed or prescriptive guidance, yet for years the Australian pipeline industry relied on cost-benefit analysis alone to demonstrate ALARP By 2013, however, it was recognised that this approach had significant shortcomings, leading the industry to commission an EPCRC study to assess it against legislative developments since the 1950s, including obligations under modern Australian Work Health and Safety legislation.

Printed: 20-Dec-2016 other similar legislation This resulted in the EPCRC Final Report, Project RP4.21A: Understanding ALARP, Rev 0, August 2015

The outcome of this report is guidance on ALARP assessment for pipelines based on a wide range of national and international industry guidance:

1) The proposed ALARP assessment questions require that a broad range of issues are considered and documented

2) In doing so, the intent is that a more complete picture of the issues is developed to support the ALARP judgement

3) Cost benefit analysis is a consideration, but it is one among many

ALARP judgments are not determined by a single number or calculation They derive from a balanced assessment of multiple, competing and complementary factors, some with measurable metrics and others without, all of which must be weighed against each other to determine whether risk has been reduced as low as reasonably practicable.

A summary of this process and outcomes is provided in HAYES, J & MCDONOUGH, R 2016

Reasonably Practicable – A Help or a Distraction In Ensuring Public Safety? APGA Conference, Perth,

As of October 2016, Appendix 1 documents that ALARP guidance has been applied to a number of recent projects, and it is being promoted for broader industry use with a view to adoption by AS2885 through the current revision process Where a Formal ALARP Demonstration is required, such as to meet AS2885.1, Section 4.7.4, the guidance is provided in the form of 35 questions organized under six general headings that must be addressed and documented.

 Current level of safety risk

 Risk drivers (other than safety)

 What more can we do?

 Risk benefits of proposed measures

APA APPROACH IN BCN230

Current level of safety risk

The current level of safety risk is documented in BCN230, Section 4, Table 3, and has been found to be

“Intermediate” As discussed above, the details of the risk assessment have not been provided to GPA, and it is not within the scope of this document to critique this process However, where it is concluded that a “Catastrophic” consequence is a credible outcome, AS2885 does not permit a risk ranking lower than Intermediate

APA's assessment concludes that a "Catastrophic" consequence is credible for the pipelines under consideration, namely Project 1 – T24 Brooklyn–Corio, Project 2 – T74 Wollert–Wodonga, and Project 3 – T112 Brooklyn–Lara, as detailed in BCN230 Sections 5.2–5.4 In each case, and in line with the discussion in Section 3.3, the maximum credible threat can cause a pipeline rupture, and in high-consequence areas a catastrophic outcome is reasonably anticipated This conclusion mirrors historic industry experience, such as the Ghislenghien incident in Belgium (2004) with 24 fatalities and 132 injuries and the San Bruno incident in the United States (2010) with eight fatalities and numerous injuries.

On this basis, APA’s assessment that the risk level is “Intermediate” is consistent with the provisions of

The proposed ALARP guidance raises a key question: for an existing facility, does it meet the standards that would be required for an equivalent new facility? The APA discusses a direct example to illustrate how these comparative standards are applied in practice.

BCN230 Section 6.2 In this case, the recently constructed T120 Victorian Northern Interconnect (VNIE) is installed parallel to the T74 Wollert – Wodonga pipeline The T120 pipeline is designed as a

“no rupture” pipeline so that it can resist the very same threats which can rupture the older T74 pipeline.

Risk drivers (other than safety)

Risk drivers extend beyond safety, spanning both obvious and more intangible factors that are often difficult to quantify Key considerations include the downstream impacts on the affected community (families, health systems, and local businesses), supply chain risk, property damage, regulatory costs, legal expenses, and the potential loss of company or industry reputation.

BCN230 provides the example of the San Bruno incident in California for reference:

The San Bruno gas pipeline explosion in California is the most representative example of a full-bore urban pipeline rupture, illustrating the catastrophic risks of such infrastructure failures The disaster killed eight people, destroyed numerous nearby assets and buildings, and costs associated with the explosion—fines and compensation included—exceeded $2 billion.

What more can we do?

ALARP guidance asks how risk can be reduced further and recommends a practical approach: generate as many improvement ideas as possible, then assess each option using a consistent evaluation, starting with the idea that offers the largest probable risk benefit This iterative, evidence-based process helps identify effective risk controls and move risk down toward ALARP By listing options and ranking them by expected impact on risk, organizations can prioritize actions that deliver the greatest safety gains while balancing feasibility and cost.

BCN230 Section 5 lists and discusses the options available to reduce risk which are provided in AS2885.1 Section 4.7.4 These are:

(a) MAOP reduction (to a level where rupture is non-credible)

(b) Pipe replacement (with no rupture pipe)

(c) Pipeline relocation (to a location where the consequence is eliminated)

(d) Modification of land use (to separate the people from the pipeline)

(e) Implementing physical and procedural protection measures that are effective in controlling threats capable of causing rupture of the pipeline

While the actions required for Items (a), (b) and (c) are relatively self-evident, this is less so for Items (d) and (e) In general terms:

MAOP reduction to a level where rupture is non-credible is technically feasible but must be assessed in terms of its impact on community supply and service continuity While removing rupture as a failure mode, MAOP reduction has little to no effect on the likelihood of pipeline penetration without rupture, i.e., a leak, so the risks associated with this failure mode remain largely unchanged.

Pipeline replacement without rupture is a viable but relatively expensive option The replacement pipe can be designed to prevent penetration, achieving no leak and no rupture, and thus providing greater risk reduction than MAOP reduction without compromising supply capacity.

Pipeline relocation is similar to pipe replacement but generally a more costly option because it extends the pipeline length, increasing project scope and duration The process is likely to require sections of no-leak isolation or containment during construction, which adds complexity and operational disruption For many operators, relocation is only justified when site constraints, safety requirements, or long-term reliability considerations outweigh the higher upfront costs, making replacement the more economical choice in most cases.

“no rupture” pipe where the route inevitably traverses high consequence areas to supply the community as intended

Land-use modification is not directly controlled by the APA, so its influence is limited within the broader planning policy framework This framework generally aims to rezone land previously used for agriculture to support urban development, thereby constraining the APA's ability to steer changes in land use.

Enhancing pipeline protection involves implementing additional physical barriers and strengthening procedural controls Physical barriers such as slabbing add a protective barrier between the pipeline and vertical threats like excavators and vertical bores, though they do not guard against horizontal threats such as HDD (horizontal directional drilling) and are relatively cost-effective Exclusion likewise provides protection from vertical threats by prohibiting risky activities within the pipeline corridor, but it is often incompatible with other land uses, especially in urban contexts While intensifying procedural measures should be considered, they do not offer the same level of protection as physical barriers.

BCDN230 Section 5.1 analyzes the “do nothing” option, emphasizing two key points: first, there is no risk benefit to choosing this option; second, it can only be considered after all other risk reduction options have been thoroughly evaluated and discounted within the ALARP assessment process.

Risk benefits of proposed measures

The general risk benefits of the proposed measures are summarized above, with a related VTS discussion in BCN230 Section 5 Among practical, effective, and cost-efficient options, MAOP reduction or protective slabbing are identified as the most viable alternatives More detailed, pipeline-specific assessments of the risk benefits for these options are provided in BCN230 Sections 5.2 (Project 1 – T24 Brooklyn – Corio), 5.3 (Project 2 – T74 Wollert – Wodonga), and 5.4 (Project 3 – T112 Brooklyn – Lara).

The risk-benefit analysis of the proposed measures centers on preventing a catastrophic event Based on overseas experience, avoiding such an event could incur monetary costs well in excess of hundreds of millions of dollars, in addition to societal costs that are difficult to quantify Refer to Section 4.2.2 above for details.

Cost of proposed measures

Following the general discussion of costs in BCN230 Section 5, more detailed, pipeline-specific assessments of the costs of the most viable alternatives are discussed in BCN230 Sections 5.2 (Project

1 – T24 Brooklyn – Corio), 5.3 (Project 2 – T74 Wollert – Wodonga), and 5.4 (Project 3 – T112 Brooklyn – Lara)

 Project 1 – T24 Brooklyn – Corio: Slabbing is nominated as the preferred option as it is substantially cheaper than the proposed pressure reduction options

Project 2 – T74 Wollert–Wodonga: Although the two options have similar costs, MAOP reduction reduces pipeline capacity APA nominates slabbing as its preferred option, on the basis that if there is increased demand in the future, additional capital to re-establish capacity will be required.

Project 3 – T112 Brooklyn–Lara designates slabbing as the preferred option because any MAOP reduction would result in a capacity reduction with no viable replacement option to offset it, thereby prioritizing sustained throughput and reliability for the Brooklyn–Lara pipeline corridor.

ALARP guidance requires a direct cost–benefit comparison of proposed risk mitigations, weighing the expected reduction in risk against the implementation costs The total proposed slabbing program is estimated at about $25 million APA supports this expenditure by citing the Ghislenghien and San Bruno disasters, which led to multiple fatalities and injuries and whose consequences illustrate costs running into the billions, underscoring the importance of prudent risk reduction.

Uncertainty

The proposed ALARP guidance includes a number of questions relating to the uncertainties in the assessment While not necessarily explicitly addressed in BCN230, the following points are noted:

 Urban growth around the pipelines (i.e change of land use) is matter of government policy, and therefore needs to be addressed (i.e this is a current and future issue)

 The consequence of an ignited pipeline rupture in an urban area is most likely to be

“Catastrophic” (as defined by AS2885)

APA has a long history designing, constructing, and operating gas transmission pipelines in Victoria, giving it deep familiarity with the threats associated with different land uses and with land-use changes across various locations.

 Following this, APA is very familiar with the physical and procedural measures required to effectively control these threats.

ALARP Determination

Australia's pipeline industry has developed guidelines for ALARP assessments of high-pressure pipelines, reflecting current national and international practice These guidelines incorporate the obligations of modern Australian Work Health and Safety legislation and other comparable laws The guidance is documented in the EPCRC Final Report, Project RP4.21A: Understanding ALARP, Rev 0, August 2015.

It is proposed that these guidelines will be incorporated into the next revision of AS2885

An ALARP assessment should not rely on a single metric due to significant uncertainty; it is a judgement based on a broad range of factors BCN230 documents the factors APA considered to determine that slabbing the pipelines under consideration is reasonably practicable In forming this judgement, APA also evaluated the alternatives listed in AS2885.1 Section 4.7.4 and concluded that the "Do nothing" option is unacceptable.

GPA believes APA has broadly followed the ALARP guidance material for assessment, and APA’s approach aligns with current best practice for ALARP in the Australian pipeline industry.

GPA Engineering has reviewed BCN230 to determine whether the statements therein regarding the requirements of AS2885.1-2012 are correct There are three relevant topics addressed by BCN230:

1) AS2885.1-2012 Section 4.7 Special Provisions for High Consequence Areas makes requirements where there is a change of land use around high pressure pipelines from rural to urban land use This includes the requirement to demonstrate that risks associated with pipeline rupture are ALARP In GPA’s opinion the explanation provided in BCN230 accurately reflects the content and intent of the AS2885.1-2012 provisions for High Consequence Areas and is sufficient for the purposes of supporting the case as presented

2) AS2885.1-2012 Appendix F Qualitative Risk Assessment provides the risk matrix which is to be used for pipeline risk assessment, and also specifies the actions required for the risk rank determined by risk assessment, and in particular, “Intermediate” risks In GPA’s opinion the explanation provided in BCN230 accurately reflects the content and intent of AS2885.1-2012 provisions for “Intermediate risks” and is sufficient for the purposes of supporting the case as presented While the scope of this Commentary Report does not include the process by which

APA risk assessments have been conducted or their conclusions, it is noted that:

 Where the consequence assessment concludes that a pipeline failure results in a

“Catastrophic” outcome (i.e inter alia multiple fatalities), the risk matrix in AS2885.1-

2012 does not permit a risk ranking lower than Intermediate, and therefore ALARP must be demonstrated

BCN230's pipeline assessment indicates that if an ignited pipeline rupture occurs, individuals within several hundred metres of the gas release would be exposed to heat radiation sufficient to cause fatal or life-threatening injuries; in urban areas, such a scenario would reasonably be classified as a 'Catastrophic' outcome.

3) Based on the tables which show the susceptibility of each pipeline to penetration and the predicted failure mode for the pipelines, and APA’s assessment of the credible threats, in GPA’s opinion it is reasonable to conclude that pipeline rupture is a credible failure mode for each pipeline

GPA Engineering has reviewed BCN230 to assess whether APA's ALARP demonstration approach for the proposed remedial actions aligns with established pipeline industry practice, in place since the 2012 revision of AS2885.1.

The Australian pipeline industry has developed ALARP assessment guidelines for high‑pressure pipelines in line with current national and international practice and the obligations of modern Australian Work Health and Safety legislation Documented in EPCRC Final Report RP4.21A: Understanding ALARP, Rev 0, August 2015, these guidelines are currently in the process of being incorporated into AS2885.

An ALARP assessment cannot be based on a single metric, which would be subject to considerable uncertainty, but must be a judgement call informed by a broad range of factors The BCN230 document details the factors APA has taken into account to form the judgement that slabbing the pipelines under consideration is reasonably practicable In forming this judgement, APA has evaluated the alternatives listed in AS2885.1 Section 4.7.4 and has concluded that the “Do nothing” option is unacceptable.

GPA believes that APA has broadly followed the guidance material for ALARP assessment, and APA’s approach is consistent with current best practice for ALARP in the Australian pipeline industry.

REASONABLY PRACTICABLE – A HELP OR A DISTRACTION IN

Associate Professor Jan Hayes School of Property, Construction and Project Management

College of Design and Social Context

Richard McDonough Senior Project Engineer GPA Engineering Adelaide, SA

Pipeline safety requires that design, construction, operation, and maintenance keep risk to workers and the public as low as reasonably practicable (ALARP) In many cases the requirements are straightforward: for example, new pipelines must meet AS2885.1 standards, and pipelines in urban areas are designed for no rupture The real challenge arises when decades-old pipelines, once built in sparsely populated regions, now sit near expanding urban development If these aging lines do not meet current design standards for the service, operators must assess whether their existing safety measures—operational procedures, monitoring, inspection regimes, and emergency response—are sufficient to achieve ALARP.

The determination of what counts as 'reasonably practicable' is a matter of judgment that will never be formally tested unless an accident occurs, yet the pipeline industry bears legal and moral responsibilities to get it right This paper draws on the diverse fields of law, ethics, social science and engineering to trace the origins of the concept of 'reasonably practicable,' explain its meaning, and set out the obligations it imposes on the management of pipeline companies.

Changes are being proposed to AS2885.1 to include more guidance on how to make ALARP judgements In this paper, we use a real case study to show how the proposed changes to AS2885.1 would apply in practice.

AS2885.1 guidance is designed to help pipeline operators make reasoned, informed judgments about the actions required to keep the public safe, supporting effective pipeline safety and risk management While risk can rarely be eliminated, applying a structured process yields safer, more consistent, and defensible outcomes when incidents occur.

Tiêu đề	Urban Encroachment Business Case Review - APA Group
Trường học	GPA Engineering Pty Ltd.
Chuyên ngành	Pipeline Engineering and Safety
Thể loại	Commentary Report
Năm xuất bản	2016
Thành phố	Unley

Định dạng
Số trang	41
Dung lượng	1,59 MB