Assessing intermittent saline inflows in urban water systems

Abstract

Urban water drainage systems' primary function is to transport sanitary or stormwater. The intrusion of saline waters has recognized detrimental effects. Especially in coastal areas, saline inflows can compromise performance by increasing the risk of untreated discharges, weakening the structural condition of concrete or metallic components, reducing the effectiveness of wastewater treatment processes and limiting the potential reuse for irrigation. Performance deterioration can be prevented by an early assessment of exposure to saline water, followed by timely actions to control its causes and consequences. The paper describes a procedure for diagnosing undue saline inflows. The procedure is based on the determination of saline inflow's magnitude, acceptance levels, and contribution to the system's performance. Contextual factors and performance indicators, and their reference values, are selected for the assessment. Options to address the problem are proposed, depending on the results. These options can relate to organizational, operational, and structural actions. Application to a case study allowed to validate the method and discuss the results. Here, saline volumes entering the system are quite relevant (almost 30%), posing problems regarding corrosion, treatment plant operation and significant concrete exposure to intermittent saline waters.

Performance assessment of the operational management of urban drainage systems: a case study of Bejaia City, Algeria

“…In fact, these functions establish a relation between the PI values and a scale of classification (Santos 2021). By comparing the result of the indicators with pre-set reference values, it is possible to assign a judgment to the result, e.g., good, acceptable, or unsatisfactory (Brito et al 2022). These performance scales can be set from the literature review, regulations standards, available assessment frameworks, benchmarking of a representative sample, or expert opinions (Brito et al 2022).…”

“…By comparing the result of the indicators with pre-set reference values, it is possible to assign a judgment to the result, e.g., good, acceptable, or unsatisfactory (Brito et al 2022). These performance scales can be set from the literature review, regulations standards, available assessment frameworks, benchmarking of a representative sample, or expert opinions (Brito et al 2022). By monitoring the result of PI over time, it is possible to assess whether the implemented actions are having the expected impact.…”