| Abstract: | Manhole shafts in sewers are prone to deterioration due to microbially-induced concrete corrosion (MICC), which can reduce their life from 100 years to 30-50 years. MICC is facilitated by sulfuric acid formed by the generation and volatilization of hydrogen sulfide (H2S). Corrosion of manholes on roads can create safety hazards. Accordingly, this project sponsored by the City of Arlington aims to identify factors that contribute to hydrogen sulfide corrosion of manholes so that these factors can be mitigated, or so that manholes most vulnerable to corrosion can be lined with protective coatings. The initial phase of the project involved collection of data from 350 manholes in the city, including liquid- and gas-phase parameters that influence corrosion, as well as corrosion depth. The manholes were divided into 5 categories based on their characteristics: presence of drop, pipe diameter, type of flow, inlets and bends, and control. Our results showed that manholes with >2-foot drop or a hydraulic jump had the highest H2S concentrations, and lowest was observed in manholes with subcritical flow. This indicates that turbulent flow increases rates of corrosion. Based on the field data, a multiple linear regression equation was developed to predict corrosion rates. |