What’s That Smell? Odor and Corrosion Mitigation in Salt Lake City

Salt Lake Department of Public Utilities (SLCDPU) has engaged Jacobs Engineering (Jacobs) to investigate odor and corrosion issues within the sewer collection system. Most critical pipes in the collection system are composed of RCP or brick, making corrosion a primary concern. A Jacobs team conducted hydrogen sulfide (H₂S) vapor and liquid phase sampling throughout the three main trunk lines in the City. In combination with system flow rates and rainfall data, this data was used to identify hot spots of hydrogen sulfide, and potential corrosion, within the sewer system. The data collected during the sampling campaign was used to calibrate a wastewater process model built for the SLCDPU wastewater collection system using the INTERCEPTOR Powered by WATS model. Wastewater quality parameter information used during calibration included temperature, pH, alkalinity, sulfate, dissolved oxygen (DO), and chemical oxygen demand (COD). The H₂S formation rate was calibrated using dissolved sulfides and sewer headspace hydrogen sulfide data. The model, in combination with bench scale testing of ferric chloride, ferrous chloride, sodium hypochlorite, and hydrogen peroxide, was used to recommend an odor and corrosion control mitigation strategy for the existing system as well as for several future build-out scenarios incorporating the Water Reclamation Facility upgrade and state prison relocation and associated collection system projects. These recommendations were further refined with fan testing at key locations along the trunk lines to address odor and corrosion concerns.