Preserving Casper's Infrastructure: A Large Diameter Pipeline Trenchless Rehabilitation Project-PPT Presentation

PPT Presentation

Pdf Summary

The City of Casper, Wyoming, undertook a long-term rehabilitation program for its North Platte Sanitary Sewer Interceptor, a 47,000-foot system of unlined reinforced-concrete pipe built between 1980 and 1983. The pipeline experienced severe corrosion associated with high hydrogen sulfide levels, which regularly exceeded the threshold for microbial corrosion.<br /><br />Investigations beginning in 2007 included GPS mapping and inspection of 155 manholes, followed by pipe cleaning, CCTV inspections, and material analysis. Findings showed extensive concrete loss—more than an inch in some locations—and indicated that groundwater injection affected corrosion conditions. The City also studied chemical corrosion-control options and tested treatments intended to reduce hydrogen sulfide.<br /><br />After years of assessment, planning, and funding efforts, the City designed a phased trenchless rehabilitation project. The final scope included approximately 7,600 feet of pipeline and 14 access structures. Insituform was awarded the contract for about $6.64 million. Construction used cured-in-place pipe (CIPP) lining, installed and steam-cured, alongside several methods to rehabilitate structures.<br /><br />Work proceeded in two phases: approximately 5,100 feet from June to December 2022, and 2,500 feet from March to June 2023. Construction planning focused on keeping the interceptor operating, preparing for potential pipeline failures, managing temporary bypasses, limiting traffic and public disruption, and protecting wastewater-treatment operations. Severe winter conditions added to the project’s challenges.<br /><br />The project was completed for approximately $6.51 million, about $125,000 below the awarded contract amount. Its extended planning and phased delivery demonstrate how careful investigation, risk management, public coordination, and adaptable construction methods can help preserve critical underground infrastructure.

Keywords

Casper Wyoming

North Platte Sanitary Sewer Interceptor

wastewater rehabilitation

sewer corrosion

hydrogen sulfide

trenchless rehabilitation

cured-in-place pipe

CIPP lining

sanitary sewer interceptor

underground infrastructure