The main goal when dealing with incidents is to resolve external alerts received by our incident centre as quickly as possible, minimising negative impacts on wheeled traffic and our customers. Repairs are carried out on elements in the sewer system, such as domestic connections, sewer pipelines and collectors, gutters and sinks, manholes, covers and grilles, spillways, enclosures and ventilation chimneys.

The electrical and mechanical installations undergo corrective and preventative maintenance and their energy efficiency is monitored. The system has numerous wastewater and rainwater pumping plants, vacuum stations and stormwater retention tanks.

The aim is to remove depositions and obstructions that prevent the system from working properly and which cause unpleasant sights and smells.

This is done through manholes using an integrated network- and gutter-cleaning management system that involves mixed impeller-suction vehicles with high-pressure water and appropriate suction capacity. For gutter cleaning, as well as the above equipment, areas of restricted access are usually cleaned manually with support from smaller adapted vehicles (water jetters), fitted with high-pressure jetting guns.

Accessible large collectors are cleaned differently, using manual cleaning methods or electric vehicles.

The purpose is to determine the state of the system in order to take action accordingly, detecting possible structural deficiencies in conduits and associated elements (such as connections, manholes and hatches).

Inspections are carried out using the following methods:

• Network inspection with vehicles fitted with CCTV.
• Manhole inspections using fixed-pole cameras.
• Collector inspections using a prototype boat-mounted CCTV camera.

This includes rehabilitation with trenchless technology and actions using conventional open trenches. The milling technique is mainly used to eliminate obstacles in the network (protruding connections, depositions, waste from polishing, and so on).

The most commonly used rehabilitation techniques involving trenchless technology are:

• Lining inside the pipes using special sleeve (complete repair for evenly distributed deterioration) or installation of packer hoses (repair for specific isolated areas of deterioration).
• Milling with Raco or Kate robots to eliminate remains of solids, incrustations, roots and protruding connections.
• Resin injection into joints and cracks (watertightness treatment).
• Internal renovation systems with polyethylene pipes, using horizontal drilling (structural treatment).