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

Power Point Presentation

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This presentation describes the North Platte Sanitary Sewer Interceptor (NPSSI) trenchless rehabilitation project in Casper, Wyoming, a large and aging wastewater pipeline system built in the early 1980s. Although originally intended to serve much greater future growth, the line now serves a city of about 80,000 and has suffered severe internal concrete corrosion caused by high hydrogen sulfide (H2S) levels and related groundwater-injection effects.<br /><br />The project began with strategic planning, funding efforts, and system-wide investigations. Phase I focused on inspecting all 155 manholes and evaluating pipe conditions, revealing that the pipeline was in worse condition than the manholes and had significant concrete loss. Phase II expanded inspections through CCTV, hydraulic cleaning, sample analysis, and structural evaluation. The results confirmed the need for rehabilitation and helped prioritize pipe segments.<br /><br />Because immediate full rehabilitation was not possible, the city also explored corrosion-control strategies, including bench-scale chemical testing and a pilot system to reduce H2S. Rehabilitation planning eventually moved forward with design alternatives such as CIPP lining and sliplining, broken into construction phases.<br /><br />The project was bid and awarded to Insituform for about $6.64 million, with work divided into an Alpha phase (5,100 feet) and Beta phase (2,500 feet). Construction had to maintain interceptor operation, minimize traffic and public disruption, manage temporary bypassing, and protect the wastewater treatment plant from cleaning debris. The project also required rehabilitation of access structures using methods like poured-in-place liners, cementitious relining, epoxy relining, and pressure grouting.<br /><br />Despite major challenges, including a harsh winter, the interceptor rehabilitation was completed successfully with budget savings. The presentation emphasizes the importance of long-term planning, risk management, public outreach, and adaptable construction strategies for aging buried infrastructure.

Keywords

North Platte Sanitary Sewer Interceptor

trenchless rehabilitation

Casper Wyoming

wastewater pipeline

hydrogen sulfide corrosion

CIPP lining

sliplining

CCTV inspection

temporary bypassing

aging infrastructure