A Comprehensive Guide to Structural & Service Grades

A Comprehensive Guide to Structural & Service Grades LP banner

A Comprehensive Guide to Structural & Service Grades

Introduction

Sewer systems are vital components of urban infrastructure, ensuring the safe disposal of wastewater. To effectively manage these complex networks, inspectors employ Structural and Service Grades, which are assigned based on defect assessments utilising specific peak and mean score thresholds, rated on a scale from 1 to 5. This article aims to demystify the process of grading sewers, elucidate the significance of each grade, and clarify how defects are scored to determine the final grade and relates to the Water Standard of Australia. 

The Significance of Grading

The grading of pipeline infrastructure serves as a critical tool in asset management. It empowers decision-makers with actionable insights into the condition and operational health of these vital systems. By assigning numerical grades based on peak and mean scores of the reported defects, asset inspections facilitate the prioritisation of maintenance, rehabilitation, and renewal efforts. This approach ensures that resources are allocated efficiently, mitigating the risk of catastrophic failures, protecting public health, and prolonging the life of essential urban infrastructure. 

Understanding Structural Grades: Gauging Structural Integrity

Image of an identified breaking defect, that will severely affect structural integrity.
Image of an identified breaking defect, that will severely affect structural integrity.

Structural Grades play a crucial role in assessing sewer conditions, providing guidance for maintenance and rehabilitation priorities. 

These grades are assigned based on the cumulative scores of identified defects, with precise peak and mean score thresholds, based on a 1-165 defect scoring scale. 

  • Grade 1:  Signifies that the sewer is in excellent condition, with no or minimal deterioration. Recognized defects may include minor surface flaws or slight wear. (Peak score: ≤5, Mean score: [0 – 1.0]) 
  • Grade 2: assigned when the aggregate scores of recognized defects, such as localized corrosion, minor cracks, or minor joint displacement. Examples of defects include root intrusions or moderate corrosion. (Peak score: [>5 – ≤15], Mean score: [>1.0 – ≤3.0]) 
  • Grade 3: Sewer pipes showing moderate deterioration with developed defects that don’t affect short-term structural integrity receive Grade 3. (Peak score: [>15 – ≤40], Mean score: [>3.0 – ≤5.0]) 
  • Grade 4: When significant deterioration is observed, with defects impacting structural integrity. Significant joint separation or extensive cracking are examples of defects at this grade. (Peak score: [>40 – ≤60], Mean score: [>5.0 – ≤10.0]) 
  • Grade 5: The direst situation structural grading, sewer failure is imminent, posing a high risk of service failure, property damage, and potentially public injury. Defects such a singular or multiple collapse’s fall into this category. (Peak score: [>60], Mean score: [>10.0]) 

Understanding Service Grades: Gauging Operational Health

Image of significant soil build-up within a water asset, which will have a dramatic effect on hydraulic efficiency.
Image of significant soil build-up within a water asset, which will have a dramatic effect on hydraulic efficiency.

Service Grades provide insight into sewer system functionality and performance, addressing hydraulic efficiency and the likelihood of sewage pollution. 

These grades are calculated as follows, based on a 1-165 defect scoring scale. 

  • Grade 1: When there’s no or insignificant loss of hydraulic performance and little likelihood of sewage pollution. Defects may include minor root intrusions or minimal sediment deposits. (Peak score: [≤5], Mean score: [0 – ≤1.0])
  • Grade 2: Minor defects causing minor loss of hydraulic performance and a minor likelihood of sewage pollution led to Grade 2. Examples include partial blockages or small joint offsets. (Peak score: [>5 – ≤10], Mean score: [>1.0 – ≤3.0])
  • Grade 3: With developed defects causing moderate loss of hydraulic performance and moderate likelihood of sewage pollution, Grade 3 is assigned. Defects may encompass root intrusions, significant sediment buildup, or moderate joint displacement. (Peak score: [>10 – ≤40], Mean score: [>3.0 – ≤5.0])
  • Grade 4: Significant defects leading to a serious loss of hydraulic performance and a significant likelihood of sewage pollution result in Grade 4. Large blockages, substantial root intrusions, or major joint offsets are examples. (Peak score: [>40 – ≤60], Mean score: [>5.0 – ≤10.0])
  • Grade 5: In cases where sewer failure or environmental pollution is imminent, immediate action, including temporary support, is warranted. Critical blockages, imminent collapses, or severe contamination potential fall under this category. (Peak score: [>60], Mean score: [>10.0]) 

As a result, the product or service becomes a joint venture between the innovator and the early adopters, solidifying a partnership that goes beyond a transactional exchange. This adaptability not only enhances the product’s features and functionalities but also cultivates a community that is deeply invested in the success and evolution of the offering.

Conclusion

In the intricate world of sewer & stormwater inspections, Structural and Service Grades provide a compass for asset decision-makers. The grading thresholds based on peak and mean scores can be used to prioritise decision requirements, ensuring the continued health and functionality of sewer & stormwater networks 

(*Please note that the references to grading & score calculations mentioned in this article apply to the Water Standard of Australia.)

About the Author


As VAPAR’s Customer Success Manager, Daniel Harkin is a passionate and dedicated professional with decades of experience in CX management. Proactively nurturing client relationships, Daniel ensures optimal product value realisation for VAPAR, while fostering long-term loyalty with clients.

VAPAR’s software offers a paradigm shift in pipe inspections. With an emphasis on AI-driven analyses, it ensures that the data received is extensive and insightful, making inspections strategic initiatives.

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