NASTT Project Profile: Trenchless Rehabilitation Supported by Diagnostic Imaging
Sep 2015 • Civil Infrastructure • Article
The City of Levis, Quebec, Canada (City) owns and operates a significant storm water drainage system that serves the city and surrounding areas. Some of this system is comprised of corrugated metal pipe. One section in particular is of high concern and was requested for immediate condition assessment to guide rehabilitation efforts.
A thorough review of the structural condition assessment of the storm water drainage section under Rotonde Avenue and Autoroute 73 in Levis, Quebec was used to formulate a comprehensive rehabilitation plan. The main body of the pipe will be referred to in Stages 1, 2, and 3 of this project (STA 0+000 to STA o+156). The downward sloping outfall section will be considered Stage 4 of this project (outfall). Two primary rehabilitation techniques have been identified as viable options for the rehabilitation of this pipe segment (STA 0+000 to STA o+156): spray in place pipe (SIPP) polymer solution and centrifugally cast concrete pipe (CCCP) solution.
A visual and acoustic assessment was carried out, four anomalies were identified, and two anomalies were chosen for BCT imaging. Locations were measured from manhole access (STA0+000) to the outlet (STA0+180).
Seams throughout the storm drain are in poor condition – several with visible voids, above and below the pipe, allowing water to run underneath causing flow-related soil failure. The ovality of the pipe diameter is greater than 10%, the majority of issues being underneath Autoroute #73. Several rock impingements were noted, the largest located directly beside the entrance of the manhole located on route #73, (STA0+137) from the access manhole on Avenue de la Rotonde. The bitumen coating throughout the pipe has become dried out and brittle, chipping during hammer testing. The outlet of the storm drain (STA0+156) to (STA0+180) is in very poor condition; two acoustic anomalies were found. Evidence of buckling and significant scour was noted. The outlet of the pipe is damaged with several large indentations.