Access to the network

Outlets

Initial sedimentation pit

Interceptor

Energy dissipation

Retention tank

Balmes / Pl sedimentation pit . J.F. Kennedy

Diagram of siphon

Chutes

Colón pumping station

Inspection chamber

Structure

The sewage system network of Barcelona is formed by a system of functional elements for the capture, transport and evacuation of the wastewater and rainwater.

These individual elements perform concrete actions:

• Entry into the sewage system network
• Channeling and circulation of liquids
• Dissipation of energy and regulation of flow
• Retention of waste
• Overcoming obstacles
• Human access

* Capture

Drains

Underground conduits which transport wastewater or rainwater from its origin, in a building or property, to a public sewer.

Outlets

Capture elements situated in a roadway and pavement and usually protected by a trash-rack. They are used for the collection and conduction of to the sewer of the runoff water.

Sedimentation pit

Situated on the flank of the Sierra de Collserola, between the torrents and inundations in the open air and the head point of the network, they are constructions for retaining the solid waste transported by rainwater and avoiding their entry into the interior of the underground channels that form the sewage system network.

* Water conduction

Depending on their location in the lattice of the network, the channels for transporting water can have different sections:
Group A. Tubular sections
Group B. Non-visitable sections of up to 1 m²
Group C. Visitable sewers between 1 and 1.6 m² of section
Group D.Visitable Collectors between 1.6 and 4 m² of section
Group E. Large collectors of more than 4 m² of section

Interceptor

Collects the wastewater before it is flushed through a spillway and directs it to the corresponding sewage treatment station.

* Flow regulation

Energy dissipation

Element used for the dissipation of the energy produced by every release of water in the connection of two conduits situated at different levels.

Water drop

Ramps or waterfalls used to reduce the gradient of the collector and consequently the velocity reached by the flow. These distribute the flow in the section and dissipate the accumulated energy in the inner span.

Absorption bowl

Water tanks situated at the foot of a drop or chute to absorb the energy of the water and brake its speed.

Retention tank

Underground constructions that permit rainwater to be stored, facilitate its regulation and avoid the risk of flooding.In Barcelona there are tanks situated at strategic points for capturing rainwater.

• University zone This is the biggest, with a capacity of 145,000 m³ of water.
• Bori I Fontestà. This has a capacity of 93,000 m³
• Doctor Dolsa Gardens. Capacity 52,500 m³
• Escola Industrial. Allows 35.000 m³ to be reached;
• Vilalba dels Arcs. Capacity: 13,800 m³
• Parc de l'Escorxador. Capacity: 50,000 m³
• Taulat. Capacity: 80,000 m³

The tanks of the sewage system of Barcelona have 18 gates which are distance tele-controlled and which permit the retention and regulation of the water in case of torrential rain. For this reason they have the name of retention tanks anti-flood, or anti-DSU (Discharge of the Unitary System).

* Retention of solids

Sedimentation pits

By using filtering or by the dispersion of accumulated energy, the flow is forced to deposit into these pits the solid waste which can deteriorate or obstruct the sewage system network.These elements require special attention for cleaning and maintenance.

Sand distribution chambers

Some inspection chambers have a bed at a level lower than the gradient of the sewer so as to retain, by decanting, the solid waste which can transport the water. So that they can fulfill their function, these elements require a high level of maintenance.

* Overcoming obstacles

Siphons

Used to avoid an obstacle situated at the same level as the channelling. By using the principle of communicating vessels, the water is channelled at a lower level, and once the obstacle is overcome, the water rises naturally.

Chutes

Steep gradient, short-distance channelling which avoids great land rises.

Pumping Stations

These raise the water to a level higher than the obstacle in order to overcome it or, simply, to achieve a height which will give the water the energy to move by gravity.
The elevation is done using mechanical pumping.

* Access

Inspection chamber

These permit people to access the interior of the sewage system.
They are normally vertical constructions and in the city of Barcelona they are standardised with a square section of 70x70cms and have propilene steps and a ductile cast cover of 70 cm diameter.