Condition Assessments Using Pipe Penetrating Radar: The Metro Wastewater Reclamation District, Denver, CO—Harvard Gulch Interceptor Case Study

Abstract

Pipe Penetrating Radar (PPR) is the underground in-pipe application of ground penetrating radar (GPR), a non-destructive testing method that can detect defects and cavities within and outside mainline diameter (>18 in / 450mm) non-metallic (reinforced concrete, vitrified clay, PVC, HDPE, etc.) underground pipes. The key advantage of PPR is the unique ability to map pipe wall thickness and deterioration including voids outside the pipe, enabling accurate predictability of needed rehabilitation or the timing of replacement. A case study was conducted to demonstrate the capabilities of the SewerVUE PPR pipe condition assessment technology for the Metro Wastewater Reclamation District (MWRD) in Denver, CO. This paper describes the in-pipe data collection at the Harvard Gulch Interceptor and subsequent analysis focusing on the results obtained from the PPR data. These include: exact measurement of pipe wall thickness, pipe wall corrosion, loss of rebar cover and mapping grout thickness around the pipe. An overview of MWRD’s advanced pipe condition assessment technology research, comparison of available technologies, and how these findings have helped improve asset management strategies is also discussed. With limited available funding and budget constraints becoming more prevalent, timing of rehabilitation and overall intelligent asset management is more critical than ever for municipalities Advanced pipe condition assessment technologies, including the SewerVUE PPR system, show promise as being cost-effective, non-destructive methods that are able to help better refine estimated remaining life of an interceptor, accurately determine overall severity of pipe degradation, as well as provide a basis for improved cost allocation and timing of rehabilitation efforts.