Field monitoring and design optimization of dropshafts with air circulation pipes

Abstract

Dropshafts with air circulation using an airshaft and horizontal air circulation pipes have been implemented for reducing downstream sewer air pressure and preventing sewer odor emission. There is a need to optimize the design for improved effectiveness and cost-saving. A one-week field monitoring program on a dropshaft with air circulation pipes was conducted in Edmonton, Canada, in order to validate the air flow model and assess the performance of the dropshaft with different air circulation pipe configurations. The air flow model was based on the upstream/downstream conditions of the dropshaft which were obtained from the field monitoring program. This study showed that the horizontal air circulation pipes on the top positions were more efficient in re-circulating air and depressurizing the downstream than the bottom ones, and increasing the size of the top horizontal air circulation pipes could significantly improve their effectiveness. This study provides guidance for designing or retrofitting dropshafts with air circulation pipes.