PRESERVING CASPER’S INFRASTRUCTURE: A LARGEDIAMETER TRENCHLESS PIPELNE REHABILIATION PROJECT

Abstract

This paper presents a project overview to rehabilitate a deteriorating large-diameter wastewater interceptor sewer using trenchless cured-in-place pipe (CIPP) for the City of Casper, WY. This project restored critical portions of the City’s main wastewater interceptor system for the next 100 years. The pipeline, known as the North Platte Sanitary Sewer Interceptor (NPSSI), represents a nine-mile conveyance system that was initially constructed in early 1980s. Since that time, the pipeline deteriorated due to the presence of elevated levels of atmospheric hydrogen sulfide (H2S). The project team that studied, designed, and provided construction observations services over a 5-year period included CEPI, BlueWater Solutions Group, and Jacobs. The contractor for this $6.7M project was Aegion/Insituform (now Insituform/Azuria Water Solutions Company). Construction of the most critical portions of the NPSSI began in mid-2022 and was completed in early 2023. It included 7,600 ft (3,600 m) of 48-54 in (1,220- 1,380 mm) pipe rehabilitation along with numerous point repairs, new junction structures, and improved river siphons and inlet/outlet structures. Despite record winter weather conditions and numerous site challenges that were encountered, the project was completed on time and within budget. The NPSSI project demonstrates that the successful renewal of a large-diameter wastewater interceptor within a stream-sensitive aquafer can be done using trenchless renewal in the best way possible. KEYWORDS: trenchless, rehabilitation, CIPP, large, diameter, wastewater