Addressing Settlement in Duct Banks: Insights from Comprehensive Analysis and Pressure Grouting Solution in Arizona

Background: The project involved addressing settlement issues caused by water infiltration in the 230KV and 69KV duct banks built on top of an existing landfill. Settlement of up to 18" had occurred over time, necessitating remedial measures.

Methodology: A comprehensive analysis was conducted, considering factors such as methane gases, electrical fields, and drilling through debris and trash. Various techniques, including the use of different types of piles, were evaluated. Ultimately, pressure grouting was selected as the most suitable solution.

Pressure Grouting Solution: The approach involved using a special grout casing with an auger to drill through the debris, trash, and soil. A torque drive and water swivel were used to advance the casing and inject grout while clearing out debris. To ensure effectiveness, grout was first installed around the perimeter of the affected areas to create containment. Specific criteria for volume, pressure, and vertical movement were established to guide the process and ensure controlled application of grout. Each application of grout was closely monitored and evaluated before moving on to the next step.

Mitigating Settlement: Lessons Learned from Complex Duct Bank Stabilization

This project exemplifies the importance of considering multiple factors and exploring various techniques when addressing complex settlement issues. By employing pressure grouting and employing meticulous control measures, the team successfully mitigated settlement and stabilized the duct banks. The lessons learned from this project provide valuable insights for similar challenges in the future, emphasizing the significance of thorough analysis and tailored solutions.