Application of Pipe Penetrating Radar for Asbestos Cement Pipe Condition Assessment

Pipe penetrating radar (PPR) is the in-pipe application of ground penetrating radar (GPR), a nondestructive testing method that can detect defects and cavities inside and outside nonferrous pipes. The advantage of PPR is the ability to map pipe wall thickness and deterioration, including voids outside the pipe, enabling accurate predictability of needed rehabilitation. This paper presents recent advancement of PPR technology together with selected case studies. A new, small diameter robotic system was developed for the condition assessment of asbestos cement (AC) sewer pipes, as well as other nonferrous pipe materials. The asbestos cement pipe scanner (ACPS) was deployed in a 250 mm (10 inch) diameter sewer main in Surrey, British Columbia. Analysis of the data revealed localized wall thinning and provided engineers with critical information to proceed with their rehabilitation plan. The 4th generation surveyor was deployed on a condition assessment project in Melbourne, Australia. This involved surveying 600 mm (24 inch), 750 mm (30 inch), and 950 mm (37.5 inch) reinforced concrete pipe (RCP), as well as 1050 mm (42 inch) brick-lined pipe, totaling 3521 m in inspection length. PPR allows utility owners to accurately estimate the remaining lifetime of pipelines, and refine the timing of repairs.