In 2021, a series of events prompted Hampton Roads Sanitation District (HRSD) to examine the conditions of pipelines at the York River Treatment Plant. CCTV footage revealed varying degrees of degradation to three primary clarifier pipelines. To restore the pipelines, HRSD explored options to excavate and replace or to rehabilitate sections using carbon fiber reinforced polymer (CFRP). Utilizing CFRP proved to be the most cost-effective and delivered the least disruption and environmental impact. Crews dewatered and sanitized the pipelines, performing condition surveys, including CCTV inspection. Extensive deterioration was discovered in the primary clarifier influent pipelines, which was not seen in the initial CCTV due to the presence of built-up concrete that had fallen from the crown of the pipe and prevented the CCTV machine from continuing all the way down the pipeline. The project team quickly relayed the condition to the owner and modified the project plan to include custom shoring. Crews then performed surface preparation followed by installation of the CFRP system and a chemical-resistant topcoat. Additional scopes included pipe abandonment as well as bypass setup and installation. This paper will highlight the investigation, analysis, design, and repair of the influent and effluent pipelines. Perspectives from the Owner, Engineer, and Contractor will be provided, along with insight on the options analysis process, and lessons learned throughout.
Copeland et al. (Thu,) studied this question.