Urban Planning, Ecological Transition, Urban Services and Housing

The drains network of Barcelona serves around one and a half million city inhabitants, along with industrial establishments throughout the municipality. It represents essential infrastructure for the proper functioning, management and treatment of the water generated. And it therefore requires considerable and constant maintenance, cleaning and upkeep work. The aim: to keep it operating in optimal condition at all times.

Cleaning of the drains network is necessary to ensure that both waste and rain water can flow through it without any solids forming a blockage, thereby guaranteeing effective evacuation.

The presence of solids within the network occurs essentially as a result of earth being washed down via the gutters and upper courses, in the case both of torrential rainfall and as a result of anomalous discharges of an industrial nature, or caused by the numerous construction works performed on public roads. This sediment is deposited in the interior tunnels connecting the gutters, and if it enters the network will be carried down by the water, remaining as sediment at the base of the incline.

The city of Barcelona has established a preventive drains cleaning plan to ensure that they function properly at all times, reducing the urgent action required to a minimum. Preventive cleaning is performed on the basis of an operational programme taking into consideration the inherent characteristics of the network in terms of cross-section, incline and frequency, along with the type of working units and cleaning systems to be deployed.

These actions serve periodically to survey the functioning and status of the entire network and the auxiliary elements, as they are cleaned and inspected at least once per year.

Working methods and cleaning units

Three operational systems are applied to Barcelona's drains:

- Rinse and extraction cleaning: This is a basic procedure employed in those areas where there is the greatest incline, and where solid waste is therefore less likely to accumulate. In this case the teams are responsible for cleaning the tunnels and guttering grilles to ensure the absence of any blockage or obstacle preventing water from entering.

- Hydrodynamic cleaning: This is applied to networks with a moderate degree of sedimentation. The mechanism employs water being pumped in at high pressure in order to shift the sediment. A vacuum pump is then used to separate the water and the solids within a vehicle-mounted tank.

Mixed vehicles are used, equipped with a recirculation and a water filtration system. The distinctive feature is that the waste water from the drains is itself used to shift the waste, thereby saving on the use of drinking water. It is calculated that some 100,000 m3 of drinking water are saved every year.

- Cleaning by pneumatic extraction:Used at those points of the network where substantial sediment deposits could build up. The mechanism employs aspiration and extraction of the waste in order to prevent it from blocking the passage of water along the drain.

A vehicle with a 12 m3 capacity tank is used, equipped with an aspiration pump with a flow rate of 3500 m3/h, capable of aspirating waste of up to 120 millimetres in diameter at heights of 200 metres and depths of 50 metres.

Every day working teams are deployed to perform a range of network cleaning tasks, divided into 3 shifts working mornings, afternoons and nights, to provide a 24-hour service. On Saturdays, Sundays and public holidays there is a permanent duty service to cover any type of emergency or incident that could arise.

Upkeep

The drains network of the city of Barcelona has in place a high-tech maintenance system. This comprises two separate types: 1) Corrective maintenance: actions taken once faults have occurred. 2) Preventive maintenance: actions intended to reduce the occurrence of faults.

Corrective maintenance:

This includes all urgent and unforeseen repair jobs requiring immediate action. Various operational units are available to perform these tasks. With a lightweight vehicle and specific tools and machinery, they can swiftly be called out to deal with any urgent incident. Such jobs would include: Repair of manholes and frames, repair of grilles, occasional repairs inside the drains, installation and repair of railings and bars protecting rapids, repair of subsidence and cavities.

Preventive maintenance methods

This type of maintenance serves to avert faults in advance, improving the service and reducing the cost by prioritising the most critical points. Various specialist units are permanently on hand to perform each of these tasks. Preventive maintenance work is performed in accordance with an annual schedule, with a detailed construction project being drawn up for each repair project.

Such jobs will include: Replacement of manholes and frames; Replacement of grilles; Replacement of inspection shaft covers; Reconstruction of foundations; Installation of stoneware troughs; Renewal of semi-accessible and tubular drains; Renewal of interior cladding; Consolidation of structures.