Risk Mitigation Strategy for Big Walnut Sewer Extension in Columbus, Ohio

摘要

This project will expand sanitary sewer service within the City of Columbus. It consists of 2.5-mile long, 72-inch finished diameter pipe to be grouted inside 10-foot diameter tunnel excavation in shale. This paper describes the multi-faceted geotechnical exploration during tunnel alignment study to minimize the ground condition risks. The tunnel will cross immediately below a buried valley with minimum cover of poor and highly weathered rock with potential soil-like inclusion. The risk mitigation strategy to cross the valley will be discussed to include contingencies and cost allowances. Design provisions to prevent impact on adjacent groundwater resources as well as other risks will be described.