Lessons Learned from a 20-in. and 30-in. CIP Inspection

The City of Elyria, Ohio (City) owns and operates a water treatment plant (WTP) on the shore of Lake Erie, approximately 5 mi from the City. The City has three critical parallel water transmission mains that convey water from the WTP to the City, approximately 5 mi southeast. The water transmission mains consist of the following: 20-in. cast iron pipe (CIP) was constructed in 1902, 30-in. CIP was constructed in 1945, and 48-in. prestressed concrete cylinder pipe (PCCP) was constructed in 1959. As part of the City's ongoing efforts to understand and minimize risk associated with buried infrastructure, Black & Veatch was hired to perform a comprehensive condition assessment of the transmission mains. This paper focuses on the lessons learned from the external leak detection inspection of the 20- and 30-in. CIP mains. The first part of this project was technology selection. Several technologies were considered to evaluate the condition of the City's CIP. Ultimately, external leak detection using Gutterman Aquascan TM-2 correlators was selected. The second part of this project was inspection planning, identifying locations to place sensors and preparing the pipeline for inspection. The third part of this project was 11 days of inspection execution, collecting acoustic leak detection data on 22,000 ft of 20-in. CIP and 26,000 ft of 30-in. CIP. The fourth part of this project was to validate the leak detection data collected and locate leaks. This document reviews inspection planning, execution, field data validations, and lessons learned during the assessment of these 20-in. and 30-in. cast iron pipes.