Organic “High-Build” Spray-in-Place Liners – An Emerging Class of Rehabilitation Methods

By Erez N. Allouche, PhD, P. Eng. and Eric J. Steward, Trenchless Technology Center, Louisiana Tech University | June 2009 Vol. 64 No. 6

In early 2007, the City of Norristown, Pennsylvania discovered that a 60-inch diameter CMP storm sewer had developed severe structural problems due to corrosion and abrasion wear. The conduit served as a drainage pipe beneath a heavily traveled highway. Excavation and replacement of the damaged pipe would have caused numerous delays and detours for traffic in the area. A Sprayroq Certified Partner was contacted to explore the possible applicability of a structural repair utilizing the Spraywall technology. The first step was to prepare the internal surface of the pipe for the application. The invert (bottom channel) had suffered severe corrosion and abrasion. To prepare this part of the conduit, a 24-inch wide concrete swath was poured along the entire 600 foot length of the pipe to rebuild the invert and make it suitable for the application of Spraywall. The conditions that the culvert was exposed to (i.e., depth of cover, hydrostatic load and any live loads) were reviewed as to provide for the proper thickness of the applied Spraywall. It was determined that 250 mils (6.5 mm) thick polyurethane liner was needed to rehabilitate the conduit. After the concrete swath cured in the invert, the pipe was power washed using a high pressurized water jet cleaner to remove debris and corroded material on the surface of the culvert. After drying, the CMP was sprayed with the Spraywall material until the desired thickness was achieved. The application of the Spraywall material took two days to complete (Figure 14).

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Fig 14. Application of a 250 mil of polyurethane coating for the rehabilitation of a 60” CMP culvert.