Tom Iseley

Assessment technologies for sewer system rehabilitation

Due to their low visibility, rehabilitation of underground utilities is neglected until a catastrophic failure occurs. This results in costly and difficult rehabilitation options. A key issue governing the selection of appropriate rehabilitation technologies, is the availability of adequate information concerning the condition of infrastructure. This paper presents an overview of the current methods and new developments for sewer line condition assessment. The focus of the paper is on internal inspection technologies, which investigate infiltration/inflow problems, and assess the structural conditions of sewer pipes. The primary internal inspection method is closed-circuit television (CCTV) inspection. The quality of information obtained using traditional CCTV is dependent on the experience and skill of the technician and the reliability of the TV picture. Other non-destructive, remote-sensing diagnostic methods include: infrared thermography system, sonic distance measurement method and ground penetrating radar technique. The features of three new promising multi-sensory systems, namely, KARO, PIRAT and SSET, are explained. The paper also discusses ongoing research efforts for automated interpretation of multi-sensory data.

COMPUTERIZED SEWER PIPE CONDITION ASSESSMENT

The paper outlines the development and evolution of a digital sewer scanner technology (SSET) and discusses the introduction of the commercial market ready systems in January 2001. Also reviewed is the automated defect recognition procedure that takes the full advantage of the digital scanning.

Modeling the Frequency of Water Main Breaks in Water Distribution Systems: Random-Parameters Negative-Binomial Approach

AbstractWater main breaks can have significant adverse social, economic, and environmental impacts. As a result, water utilities seek to be proactive and implement asset management programs to reduce the frequency of water main breaks and mitigate their impacts. A key to the success of these asset management programs is the ability to quantify the effect that a variety of factors may have on the likelihood of water main breaks, and hence identify those pipes that need to be inspected frequently. Using water-main break data for a 21-year period from two U.S. cities in the Great Lakes region, this paper demonstrates a methodology to estimate the system-wide monthly frequency of water main breaks as a function of a number of explanatory variables. Using a random-parameters negative-binomial approach, the statistical estimations show that pipe diameters, average pipe age, distribution of pipe age, pipe material, time of year, and mean monthly temperature all have a significant impact on monthly water main bre...

Empirical Assessment of Unobserved Heterogeneity and Polyvinyl Chloride Pipe Failures in Water Distribution Systems

AbstractAn understanding of the failure patterns of pipes in water distribution systems is critical to cost-effective system-maintenance planning. Failure patterns, which typically measure the freq...