Comparison of two sewer condition assessment protocols in S. Korea

Abstract

The operation and management of social infrastructures can create significant headaches for municipal governments. Sewer systems are no exception, and prioritizing plans and strategies for asset management is usually adopted as a cost-effective solution. The condition assessment, which is an important element of asset management, provides current information about the condition of municipal facilities. Condition assessments were first used by Water Research Centre (WRc) in the UK, the country with the longest history of sewer management, and are now widely used in many countries. Korea uses the condition assessment protocol developed by the Ministry of Environment (MOE), but as this protocol does not fully reflect the underground environment in Korea, the assessments and judgments are ambiguous. The sewer condition assessment and rehabilitation decision-making (SCARD) program developed by this study is based on the MOE protocol with the defect items, score, and condition grading system modified in consideration of the type of buried pipelines in Korea. To compare the assessment results produced by these two protocols, a closed-circuit television inspection was performed on 11 km of sewer pipeline in the sampled area in P city. The inspection indicated that SCARD set a higher score of structural defects common to both protocols for items that affect the collapse mechanism (fracture, damage, etc.). The amount of pipeline that received a grade of five for internal condition rating of identified structure defects was 45% with the MOE protocol, which was much higher than the 0.6% given with SCARD. This result showed that there was a big difference between the two protocols in condition grade evaluations of structural defects. In the future, the findings of this study can be used to develop an objective protocol reflecting actual sewer pipeline conditions.