Problem: The city of Muscatine, Iowa, experiences high-flow conditions in its sanitary sewer interceptors that run through flood control levees on the Mississippi River. As a designated critical sewer, the U.S. Army Corps of Engineers ordered the city to inspect its interceptors on a regular basis. However, bypassing and dewatering high-flow pipes so they can be taken offline to accommodate CCTV inspection can be an expensive and time-consuming process, often with mixed results.

Solution: The city chose instead to use low-voltage conductivity to test its large-diameter mains. By turning off the pump station and allowing a temporary buildup in effluent flow, Electro Scan, in partnership with Municipal Pipe Tool, was able to inspect all 3,000 feet (12 segments) of 24- and 27-inch CIPP-lined RCP in less than a day and half. Additionally, defects often not seen on CCTV were located and quantified in gpm.
All work was done in accordance with ASTM F2550 and newly issued 7th Edition, Volume 1 of the Operations & Maintenance Manual of Wastewater Collection Systems.

Result: While nine of 12 pipes had little to no defects, two segments had multiple defects. In fact, combined defect flows for the two pipes accounted for nearly 80 percent of the infiltration flows for the 3,000-foot project. The city was happy with the speed and efficiency of the project and the level of data provided. 800/975-6149; www.electroscan.com.