Petrographic examination used to analyze a distressed sewer line coating

coating failures (Figs. 1 and 2) and deterioration of the interior concrete surface had occurred in many portions of a Midwestern city sewer line, the city officials wanted to recoup damages. A proposed remedial plan developed by the city's consultants with a price tag of approximately $24 million served as the catalyst for the city to take legal action against the project designers, contractors, and coating and pipe suppliers. In turn, several area law firms representing the contractors engaged an investigative team. The team's mandate: evaluate the current condition of the sewer line, determine the cause(s) of the reported distress, and recommend remedial measures so that the line would perform its intended function for the remainder of its 50-year design life. This article describes the findings of the investigative team. W