Assessing intermittent saline inflows in urban water systems

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.

Innovation results of IAM planning in urban water services

The requirement to provide urban water services continuously while infrastructures are ageing, imposes the need for increasingly sustainable infrastructure asset management (IAM). To achieve and maintain adequate levels of service, the AWARE-P IAM methodology has been applied in collaborative projects launched by the National Civil Engineering Laboratory, in partnership with IST (Technical University of Lisbon), Addition (software company) and several water utilities. The objective of these projects is to support urban water utilities in the development, implementation and maintenance of IAM plans. To guarantee the success of IAM planning, following the AWARE-P IAM methodology, utilities are required to: consider that the infrastructure has system behaviour and lifespan is indefinite and guarantee the full-alignment of IAM planning with organisation objectives. By analysing the strategic and tactical plans of participating utilities, the proposed methodology principles are discussed and supported. The main innovation results from the implementation of IAM planning are also presented and discussed, including the challenges of setting up an IAM process, together with the major benefits and drawbacks that come up when developing IAM plans. The results were demonstrated by the effective implementation of 16 strategic and 14 tactical IAM plans by the participating utilities.