Trenchless Technology Applications as a Tool in Asset Management

It seems asset management is something we hear about or read about every day.

Asset management of the underground infrastructure is becoming more and more important as the latest tool for municipalities and agencies for improved operation, management, maintenance, funding and customer service.

Trenchless technologies can be an important part and have direct applicability in the renewal and improvement of our pipeline infrastructure. This article will describe an overview of the basic elements of an underground infrastructure asset management program and describe how the use of trenchless technologies can be a part of such a plan.

Need for Asset Management

Since the mid-1900s, the trend has been to build the infrastructure to support the population growth in our urban areas and to generally avoid any maintenance until there are failures. We’ve read about the American Society of Civil Engineers’ (ASCE) assessment of the nation’s water and wastewater infrastructure being graded as a D-minus. The unfortunate part is that the infrastructure is not getting much better in spite of the work many of us have been doing in recent years.

Asset documentation is one of the first steps in Capacity, Management, Operation and Maintenance (CMOM) and Governmental Accounting Standards Board Statement 34 (GASB 34) compliance. The elements of these methods are essentially an asset management program, and many times regulators will apply these concepts as part of sanitary sewer overflow (SSO) programs. The intent of such an approach is to get the community to be forward-looking and develop strategies for the proper planning, inventory compilation, condition assessments and understanding of level of service needs for each asset within the system. This proactive approach is preferred as compared to what’s been done in the past — being reactive in spending time, money and resources doing emergency repairs and replacements.

In using an asset management approach, one of the key objectives is to provide improved customer service and to demonstrate to the ratepayers that the utility is being proactive and no longer reacting to emergency breaks. Increased customer confidence will provide support for rate increases and work efforts needed in a capital renewal and replacement program. Sustainability will be related to meeting level-of-service requirements, reducing the impact on the environment, efficiently using existing capacity, promoting responsible growth and in providing sufficient funding to build and rebuild the systems now and into the future. Also, the proactive approach will be more cost-effective over the long term.

Asset Management

Much of the focus in typical asset management programs seems to be on the mapping, inventory and condition assessment or ratings as summarized below:

GIS Mapping: Typically, one of the first steps is to prepare a map of the system. Most of the time, GIS methods are used so that all data can be tracked and linked electronically.

Inventory: Once the system is mapped, an inventory is made to document each length, diameter and type of pipe in the system. This will become important in one of the next phases related to risk assessment.
Sometimes it is found that a particular type of pipe material and/or age is in better or worse condition than other types of pipe, and as a result, may need to be addressed sooner or later in the program depending on its condition.

Condition Assessment: A condition assessment is intended to document physical defects, as well as process or operational considerations. It’s important to note also that many times it will be necessary to develop a prioritization program just to conduct the inspection work. Physical defects include such conditions as sediment deposition, grease, roots, cracked and broken pipe, deformation, corrosion and tuberculation in pipelines, manhole defects and/or deterioration in pump stations or other structures. For example, in a sewer system, condition assessments are typically made using man-entry inspections or using remote-controlled, closed-circuit television inspection techniques or other more sophisticated methods such as sonar or laser profiling.

Many times, sinkholes or depressions in the road surface are indicative of problems underground. Pipeline inspections in these locations generally find pipe defects such as a partial pipe collapse or out-of-round distress. Past pipe repairs may also be a source of future problems if joints aren’t properly connected or if substandard backfill material or improper compaction methods were utilized. Grease blockages can have devastating impacts on the system and can be one of the more prevalent reasons for SSOs.

Capital improvements throughout the system will likely be based on the condition of the existing system and the need for any renewal and/or replacements; growth or changes in demand (flow) as a result of new development or urbanization; and system enhancements to improve levels of service, reduction of risks, or possibly address regulatory requirements. Considerations should also evaluate process considerations to assess the system’s ability to meet operational or functional requirements now and in the future; project assumptions and the likelihood of these changing over time; assessment of project risks and impacts; evaluate alternatives; calculate financial impacts on user rates and/or taxes; and to the extent possible, verify accuracy of the information and data used in the development of the asset management process.

Risk analysis considerations described above are essential to understand the development of the basis for the program. It is also essential to understand how other aspects of an asset management program can be applied in the improved operation and maintenance, greater risk management and more proactive capital planning programs. Once the condition assessment is made for the system, an evaluation is then needed to understand what the likely ways that each asset can fail, what will be the impacts of the failure, analyze the most critical components and then collect data to rate the risk of failure for each asset.

Risk of Failure: There is nothing more expensive in terms of dollars and public confidence than a catastrophic failure of a large water or sewer pipe. The cost for such a repair is significant, not even accounting for citizen disruption and impact such an event presents. Failure to perform or catastrophic failure as it pertains to underground infrastructure can be related to many modes such as:

• Overflows due to insufficient capacity
• Structural collapse due to corrosion or age
• I/I sources
• Poor condition due to roots, grease, sediment, cracks and other defects
• Age and type of material
• Inability to easily access or maintain the pipeline resulting in poor efficiencies.

Each of these types of conditions is related to the potential risk of failure for each asset. Understanding and evaluating the likely failure modes for each asset provides a more complete assessment as it relates to the consequence of failure.

Consequence of Failure: This consideration relates to an understanding of the consequence of failure of each asset to evaluate the impact should there be a failure. Factors to be considered include: environmental sensitivities such as wetlands and water bodies; sensitive receptors such as neighborhoods, schools and hospitals; regulatory compliance; historical structures or locations; parks or prominent landmarks; major roadways or railroads; redundancy; flexibility to adjust to any failures or problems; and operation and maintenance impacts. Understanding the function each asset has is also important as a large diameter interceptor sewer is generally more critical and has a more significant impact should it fail as compared to a building lateral sewer. Similarly, pump stations may have a high consequence of failure due to the difficulty in getting backup capability.

Risk Assessment Matrix

Each failure mode is evaluated in terms of failure consequences and failure probabilities for each asset. Consequence categories will be different for each system and will reflect specific priorities in each system. A weighting factor is applied to each category to determine the relative risk rating for each asset. Once this type of risk analysis and rating is performed, the next step is the planning for upgrades and development of a capital improvement plan and an operation and maintenance plan.

The prioritized rating or listing will help identify assets that need immediate repairs or replacement, remedial measures such pipe cleaning or grease removal to restore capacity and phased implementation of capital improvements over the short- and long-terms.

Benefits of Asset Management

Our role will be to optimize and maintain the infrastructure that has been built in our communities by being more efficient in its operation to ensure that it will last for future generations. It is certainly less expensive to rebuild underground infrastructure and to conduct an ongoing renewal program then it is to deal with a major collapse or system replacements. Asset management is not a one time event — it is a way of doing business.

It is in this way that trenchless technologies can be applied in repairing, renewing and replacing our underground infrastructure, to stay in compliance with regulators and to provide improved customer service. This type of focus will preserve the investment made in our infrastructure over the past 30 to 50 years and redirect it to the renewal and replacement of existing systems.

These are the basic principles and challenges of an asset management program and with these concepts and a better understanding on the use of trenchless technologies, greater awareness will help advance such programs and be an important aspect in improving our nation’s underground infrastructure.

John J. Struzziery, P.E., is principal engineer for S E A Consultants Inc., Cambridge, Mass.