Frost-Shielding Methodology and Demonstration for Shallow Burial of Water and Sewer Utility Lines.

Burying utility lines below the maximum frost penetration depth can be expensive when difficult digging conditions are encountered or where existing obstacles make the desired depth expensive to achieve. Protecting the pipeline from freezing by adding an insulation shield would allow a shallow burial option. This can reduce excavation costs or avoid the relocation costs of moving the pipeline to an unobstructed location. A finite-element program was developed to model various subterranean heat-flow situations. It was used to design frost shields for a water line in northern New Hampshire through a 4-year Construction Productivity Advancement Research CPAR project with the City of Berlin Water Works, the United States Army Cold Regions Research and Engineering Laboratory CRREL, and the Owens-Corning Specialty and Foam Products Division as partners. Test sites utilizing shielded pipes were constructed, and simple techniques were explored to expedite the installation of the frost shields. Temperatures at the test sites were recorded both to verify the numerical model and to monitor the shield performance. Overall, the numerical model was capable of very good temperature predictions and provided valuable guidance for the frost shield design. The industry partner participant in the CPAR project, Owens-Corning Specialty and Foam Products Division, intends to market the concept of frost shielding water and sewer lines to state, city, county, and municipal agencies responsible for designing and installing such services. This marketing will be supported by design literature, training of in-house engineers and sales personnel, a case study of this CPAR project, and technical support from Owens-Coming.