Conducting Safe Extended Off-Tether Manned Entry Pipeline and Tunnel Inspections – The El Monte Raw Water Pipeline Inspection

This paper presents the planning and implementation needed to safely and effectively conduct manned entry off-tether and out of line of sight pipeline and tunnel inspections for the El Monte Raw Water Supply, a 13 mile long pipe system that had not been inspected since constructed in the 1940s. It varies in diameter from 18” to 72” diameter, in depth from 15’ to 300’, and is constructed of 5 different materials with many different styles of manways, vents, and sags/blowoffs that affected the inspection design. Due to geography and in ability to locate manways and blowoffs, inspections varied in length from 3000’ long single point entries (deadhead) to 1.5 mile long tunnel inspections. These works were conducted in California in 2014 and 2015 using specially modified pipe carts and BMX bikes. We will review record plan review, pipeline dewatering, steep slope management, submerged section safety, ventilation and air exchange calculations, emergency air supply, communications, pump lock-out tag-out management, confined space entry, deep hole entry, entry and exit planning, bike and cart modifications, lighting, inspection documentation tools, and inspection methods.