Urban Pipe Assessment Method and Its Application in Two Chinese Cities

Abstract

With urbanization in China, the sewer system is increasing in scope, and as a result sewer pipe defects have appeared frequently and caused problems. For example, sewer pipe defects lead to the leakage of wastewater, which may pollute groundwater in northern China. On the other hand, underground water may flow into the sewer pipes in southern China as the underground water level is higher than the sewer pipe (unlike in northern China), which dilutes the inlet wastewater in terms of COD to the wastewater treatment plant, reducing the treatment and operating efficiency. As some large cities in China are gradually being equipped with CCTV devices, the demand for an evaluation method usable by Chinese operators is urgent. Therefore, an objective and comprehensive evaluation system should be established to avoid defects and provides real-time practical suggestions under the current conditions of China. Fuzzy mathematic methods in sewer condition evaluation were utilized to decrease the uncertainty during the evaluation process in some studies, but the reliabilities of the evaluations varied based on different fuzzy methods chosen. Thus, fuzzy mathematic methods were introduced in the whole process of evaluation to eliminate artificial errors and give more objective assessment results. A novel comprehensive sewer condition assessment method was also established.