Evaluating emerging structural inspection technologies for high-risk cast iron water mains

Structural inspection is an important component of asset management and involves quantifying current asset condition and remaining life. Research is being conducted across a wide range of fields to develop structural inspection technologies that can reduce costs and improve effectiveness for multiple industrial and infrastructure applications. Some of these technology developments may be transferable to the structural inspection of water mains, while others may not be feasible for water mains if they do not address appropriate structural issues and/or are not as cost-effective as competing methods. To help guide agencies in addressing the most important issues relevant to high-risk water mains, the U.S. Environmental Protection Agency (EPA) initiated a project to develop a protocol to strategically evaluate the feasibility of structural inspection technologies for use on large-diameter cast iron water mains. The protocol is intended to be used for periodic expert panel reviews for evaluating the prospects of proposed innovations to pipe inspection technologies. This paper provides an overview of the potential failure modes, mechanisms, and distress indicators for large-diameter cast iron water mains; briefly discusses structural inspection technologies; and presents the screening protocol. The screening protocol evaluates the feasibility of accessing the water main for inspection, the detection of specific anomalies, and the cost of technology development and utilization. A trial application of the protocol on eight technologies is provided as well. It is recommended that agencies interested in supporting structural inspection technology development use this protocol as a screening measure to determine if a proposed technology is applicable to large-diameter cast iron water mains based upon its ability to detect key distress indicators and to be implemented at a reasonable cost.