Framework

The PENSAARP 2030, the new Strategic Plan for Water Supply and Wastewater and Rainwater Management, is under public consultation. In this section, we invite you to take a guided tour of the plan and participate in this consultation. We have previously described in detail each of the twenty objectives. In addition to these objectives and the necessary measures, we describe here the specific issues associated with stormwater management, seeking to contribute to encourage the ongoing public discussion.

Purpose of the rainwater service

The management of rainwater services must aim to avoid inconvenience and damage caused by flooding in inhabited areas, namely in terms of protecting housing, commerce and traffic, and must also bear in mind the need to reduce undue and unwanted inflows systems to avoid downstream pollution problems. It should seek, albeit in a necessarily limited way, to enhance the use of rainwater as an alternative source of water.

Territorial scope of the rainwater service

The rainwater service should essentially cover urban areas, where it becomes more relevant for the community in view of the impermeable areas that are created. It must be properly articulated with the existing ecological structure (parks and gardens) and the contributing hydrographic basins. In principle, it does not include rural areas or the management of rainwater outside urban perimeters, such as the drainage of roads, paths and underpasses in rural areas, nor water lines that cross urban perimeters.

Physical boundaries of stormwater service

The stormwater service must have its upstream boundary in the gutters, sinks or equivalent devices, as well as in the connection boxes to the building’s rainwater collection systems. It must have its downstream boundary at discharges into the water environment (rivers, reservoirs, transitional and coastal waters), in urban green areas or at the delivery points of water for recovery. Therefore, it excludes the service provided to the community through ditches and cleaning of gutters and drains on public roads, which must be integrated into the service of cleaning streets and green spaces. The service also excludes green solutions such as permeable pavements, bioretention systems, vegetated ditches, infiltration trenches or wells, infiltration basins, retention basins, constructed wetlands or macrophyte beds, which must be integrated into the service of spaces green, unless they are physically integrated into the system (for example, retention basins integrated into the drainage network). It also excludes the cleaning of beaches and water lines.

Stormwater service management

Stormwater governance, whenever significant use is made of collectors, must be integrated with wastewater governance, assuming that this transition is gradual. Joint management has the advantages of achieving economies of scale, flood risk management, effective control of undue inflows to wastewater systems, adoption of a common asset management policy, use of rainwater for urban uses (e.g. irrigation, urban cleaning), the adoption of solutions adapted to natural conditions with a reduction in the length of buried collectors, and the easier adaptation of management entities to the regulation regime. On the contrary, when it does not make significant use of collectors, it should remain in the municipal management of public space, which has the advantages of greater effectiveness in the response to urban floods, articulation with planning and urban licensing and articulation with the urban cleaning.

Infrastructural design of the rainwater service

New wastewater and stormwater systems must be built physically separate, and existing unitary systems must gradually evolve into separate systems, taking advantage, whenever possible, of the necessary rehabilitation interventions. The stormwater management service must jointly use conventional collector solutions and green solutions. Expansion and rehabilitation interventions, as well as hydrographic renaturalization, must prioritize green solutions. Infrastructures for rainwater services must be subject to cadastral and operational registration, like other infrastructures, including rejection points in the receiving environment.

Economic and financial sustainability of the rainwater service

The PENSAARP 2030 assumes that it is important to reinforce the funding of the separate rainwater management service to ensure its sustainable management, in a long-term perspective, including its evolution towards green solutions.

It analyzes five possible options to ensure the economic and financial sustainability of the stormwater service:

• Option 1: Revenues come exclusively from the municipality through the city council budget.
• Option 2: Revenues are shared between the municipality and users; municipal revenues come from the municipal council budget, while user revenues come from the wastewater management tariff in its fixed or variable component.
• Option 3: The revenues come from the sharing between the municipality and the users; municipal revenues come from the municipal council budget, while user revenues come from a specific fee for stormwater management. This should be a function of the waterproofing level of the property.
• Option 4: Revenues come exclusively from users through the increase in the wastewater management tariff, in its fixed or variable component.
• Option 5: Revenues come exclusively from users through a specific stormwater management tariff. This should be a function of the waterproofing level of the property.

Option 3 translates into the best balance for management entities whose level of development and knowledge of infrastructures and costs are high. It promotes greater equity by sharing expenses simultaneously between the municipal user and the numerous individual or collective users; therefore allows for better management practices both by the municipal user and by individual or collective users, such as promoting the infiltration of rainwater, avoiding surface runoff with increased flows downstream. It also promotes greater transparency and ease of explanation to individual or collective users and their perception through the allocation of actual expenditures to the three services, water supply, wastewater management and rainwater management. In order to encourage good practices by individual or collective users to reduce the inflow of rainwater, the specific tariff for rainwater management can be scaled according to the level of waterproofing of the property. In summary, this option maximizes strengths, minimizes weaknesses and generally introduces the right incentives for better stormwater management.

However, option 2 also promotes equity in the distribution of expenses and efficiency in the allocation of incentives between the municipal user and the numerous individual or collective users. If the wastewater management tariff, as far as rainwater is concerned, translates into an increase in the fixed component, good practices by individuals can be encouraged to reduce the inflow of rainwater to building rainwater systems through the exemption of this component if the individual demonstrates the adoption of green solutions for the drainage of rainwater on his property. Thus, this option also maximizes the strengths, minimizes the weaknesses and introduces, in general, the incentives that are intended to be ensured, although not disaggregating the price for the two services. However, in most situations, at the current stage, there is a practical difficulty for individuals to influence the management of their private space. On the other hand, incentives for adequate urban management by municipalities can be promoted through efficient articulation between management entities and municipal executives, who are increasingly aware of the need to promote green solutions.

In summary, the strategic plan advocates the need for sustainable management of the rainwater service, for which the reinforcement of the respective funding is crucial. The financing modalities for this service must be chosen by the municipalities considering the desirable equity in the distribution of incentives. The use of a wastewater management tariff (option 2) can be an effective solution to quickly promote knowledge and management of assets dedicated to the service of rainwater. The use of the rainwater management tariff (option 3) is, in conceptual terms, the one that most effectively translates into an adequate allocation of incentives.

Human resources of the rainwater service

Training is recommended for the human resources of management entities, for example in urban hydrology and rainwater drainage systems, asset management and automated infrastructure management, as well as consolidation of the information system of entities in the water component rainwater.

Regulatory framework for the stormwater service

The scope of regulation of services by ERSAR should gradually include the rainwater service with regard to systems mainly of networks (urban water cycle), with the regulator being able to exclude the remaining cases. The mandate of the environmental authority (APA) must integrate the disposal of rainwater, which includes the control of green solutions, according to a joint vision of the water cycle and the sources of pollution of water resources, including licensing and inspection.

Monitoring aspects of the stormwater service

The expansion of the sector’s current regulatory assessment system is envisaged with a set of performance indicators, in a parallel logic to the existing ones, which annually monitor the stormwater management service in separate systems, similarly to what happens with the services of water supply and wastewater management.

Conflict management mechanism between high and low over rainwater

Higher billing for wastewater management services in systems with a significant contribution from rainwater should encourage the optimization of separative systems and the transition whenever possible from unitary systems to separative systems, with the consequent reduction in costs. This avoids the potential conflict between the two parties when the downstream system is unitary or pseudo-separative, to the extent that, in periods of precipitation, the affluent flow to the upstream systems increases, and, with that, the value of the respective invoice. The option of not billing these increased flows is not correct, as it does not allow for an adequate distribution of service costs by municipal users, not encouraging the efficient management of rainwater and wastewater services.

Articulation of the rainwater service with the territory

The infrastructures of the rainwater management service must be object of reinforced articulation with urban planning and hydrographic management, with articulation mechanisms that enhance multiple synergies.

Articulation of the rainwater service with civil protection

The stormwater service management entities must be trained to respond to floods through articulation with local civil protection authorities, to ensure adequate emergency response to extreme weather events associated with urban floods.

Participation in the public consultation

If you have comments or suggestions for improving this topic of the strategic plan, participate in the public consultation through the following addresses:

https://www.consultalex.gov.pt/ConsultaPublica_Detail.aspx?Consulta_Id=239

https://participa.pt/ pt/consulta/project-resolution-of-the-council-of-ministers-approving-the-pensaarp-2030

Read the next text in this series, available very soon

PENSAARP 2030: What aspects to consider in environmental management?