GSD Sewer Interceptor Replacement

HEI was selected by the Galesburg Sanitary District to analyze options and provide preliminary and construction engineering services for the rehabilitation of 1000' of sewer interceptor. The existing sewer interceptor was a 3' high by 6' wide box section constructed of precast concrete box culverts. The box culvert joints were leaking and causing significant infiltration. The sanitary district asked HEI to analyze options including different types of lining, replacement, and joint repair. 

Analyzing approximately 15 different lining, joint repair, and full replacement options, it was decided that full replacement was the most cost effective. The full replacement option included approximately 1000' of 60" pipe, 4 new 8' and 9' diameter manholes, 3 existing structure reconfigurations and bypass pumping. The project was complicated by several factors including the 20' depth of the new 60" pipe, 5-million gallons of daily flow that needed to be maintained throughout construction and the 15' deep concrete storm water channel immediately adjacent to the 20' deep excavation required to install the new pipe. After consideration of several different types of sanitary sewer pipe, HEI design staff specified Centrifugally Cast Fiberglass Reinforced Polymer Mortar Pipe. This pipe provided the best balance of life expectancy, ease of installation and watertight joints.