Underground infrastructure is taking a hit with the lack of appropriate methods of managing it. The sewer and water networks in cities are in a state of degradation because of inadequate inspection methods, lack of maintenance programs and poor quality control measures. Asset management is a tool that can be used to manage assets such that costs are minimized over the maximum possible period of time. This can be done by providing the required information at the right time to the concerned people so that the right decision regarding repair or replacement can be made.
Trenchless technology has been developing various methodologies over the past 30-40 years that have proved useful in inspecting and assessing buried utilities. Trenchless technology can prove to be a great asset in managing buried utilities such as our sewer and water networks if used appropriately.
The American Public Works Association (APWA) Asset Management Task Force defines asset management as “A methodology needed by those who are responsible for efficiently allocating generally insufficient funds amongst valid and competing needs.”
AUSTROADS, 1997 defines asset management as “A comprehensive and structured approach to the long term management of assets as tools for the efficient and effective delivery of community benefits.”
Trenchless for Asset Management
Asset management is a hot topic now as municipalities scamper to manage deteriorating underground infrastructure before it fails. Trenchless technology seems to be the solution to this demanding situation that can lead to high costs in terms of repair and renewal if adequate measures are not taken in time.
The tendency to wait until infrastructure fails has led to an overload in pipelines that need repair or replacement. Cities have always focused more on building additional infrastructure to meet the demands of a growing population than to paying attention to failing infrastructure. These overlapping new and old pipelines have become more challenging to rehabilitate.
The American Society of Civil Engineers (ASCE) has graded the water and wastewater infrastructure as D minus. Trenchless technology can be used to inspect these degraded pipelines using remote inspection methods such as closed circuit television (CCTV) cameras and robotic crawler cameras that can be used to assess the condition of pipelines from within. Sewer scanner and evaluation technology (SSET) uses an optical scanner that provides a 360° view of the inside of the pipeline and has a gyroscope for meander measurement, an inclination meter and 3D imaging technology.
Asset Management Techniques
Asset management processes focus on geographical information system (GIS) mapping, system inventory and condition assessment. Software for asset management has developed database and workflow management systems and needs to collect and input appropriate data into the model along with standard assumptions for cost of replacement and service life of rehabilitated pipelines. Ground penetrating radar (GPR), ultra wide band (UWB) and sonar are also used to investigate and assess the condition of pipelines.
A map of the sewer or water system is a good way to start so that all available data can be linked and tracked. The sewer and water lines are physically located and plotted to make it easier for sanitary crews to locate blockages faster. It also helps in engineering new lines if any are required in the future. Existing drawings, field verification and global positioning satellite (GPS) systems are combined to locate all manholes, including private lines. (Read Dig We Must: Small City Manhole Rehabilitation.)
Inventory is done by documenting the pipe material, length and diameter of pipes that exist in a system. This is an important step in making a condition assessment because some pipe may need earlier attention than others in a system, depending on its material and age.
Condition assessment of pipelines is carried out to determine and document physical defects such as sedimentation, root intrusion, corrosion, tuberculation, cracks and deterioration of related structures. In a sewer system, condition assessment is carried out by physical man-entry through the manhole, CCTV remote controlled inspection and sonar or laser profiling.
Sinkholes or road depressions are also indicative of pipe collapse or distress, improper joint connections, substandard backfilling and improper compaction.
Action Based on Asset Management Assessment
The capital improvement and investment on a sewer or water system will depend on the need for repair, replacement or renewal, need for improving flow based on urbanization and growth, ability to meet functional requirements currently and in the future, meeting government regulations or improving the system for better service life and reduction of risks. These factors are important to understand how to use asset management to improve operation and better maintenance programs.
Condition assessment helps evaluate the likelihood of asset failure, impact of the failure and analysis of critical components. The data collected can be used to estimate the failure risk of an asset and is very important because failure of a system can be a public inconvenience and financial catastrophe including direct cost, indirect cost and social inconvenience cost.
The factors that can lead to catastrophic failure are collapse of structure due to age and corrosion, inflow/infiltration (I/I), inadequate or infrequent maintenance due to access restriction, overflow due to overloading of system, etc.
Benefits of Asset Management
Asset management helps evaluate these issues and take appropriate action before a failure can occur. However, the impact of a potential failure also needs to be assessed based on where it can occur, such as near environmentally sensitive areas like wetlands, forests and water bodies, near highways and railroads, historically significant areas, schools and hospitals.
While completely upgrading the infrastructure may be cost effective in some cases, it is not always the solution. Regular assessment and maintenance is a better option because asset management is essentially an ongoing process and includes renewal and replacement. (Read How To Bid On That Trenchless City Project.)
Optimizing and maintaining our infrastructure can ensure that the next generation does not have to bear the cost of a failed system. Trenchless inspection methods can be used for asset management and trenchless rehabilitation methods such as cured-in-place pipe (CIPP), sliplining and pipe bursting can be used to line or replace deteriorated pipes in the system.
Since trenchless methods require lesser space than the traditional open trenching method, it is cost effective in the long run and environmentally friendly as it reduces the carbon footprint.