New plant for wastewater treatment on Cham section of the motorway

Tyres, bits of the road surface and brake pads, as well as oils, combustion residues and salts, typically accumulate on busy roads, and these deposits are washed away when it rains. In order to prevent contaminants and pollutants, such as heavy metals and hydrocarbons, from getting into the water table, the wastewater from roads is treated. On many motorway sections in Switzerland, road wastewater treatment plants (Saba) are therefore operated by the Federal Office for Roads (Astra) to clean the wastewater. Construction work on one of these installations system has been taking place alongside an eight-kilometre section of the A4, from the Zug connection road, through the ‘Blegi’ junction to the Cham connection road since last August. Four pumping stations are being built to supply the required water from the various sections of the Saba Lorze, which transport the water to the cleaning system.

In the Saba, the water flows through a sedimentation basin, where substances such as sand and gravel are deposited. Waste, such as cigarette filters, float on the top and are skimmed off. The wastewater is then pre-cleaned. In the sedimentation basin, and a large proportion of the fine particles sink to the bottom, where they are sucked up as sludge. After the wastewater has passed through a sand filter in a next step, it can either be discharged into the ground for infiltration, or be discharged into a body of water. In Cham, for example, it is directed into the Lorze.

"Work is currently being carried out at the Cham exit road and the Zug exit road," says project manager Nicole Schulz. The Cham and Breiten pumping stations will also have to be built, and the work is carried out in stages.: "We’re well on schedule." she confirms.

                                            45 people are currently working on this project.

The work required for road drainage is no more complex than other construction work on highways. As everything takes place alongside the traffic lanes that are in use, traffic does not have to be particularly affected. But there are still challenges. Nicole Schulz explains: "In order to construct the large sedimentation basin, rock has to be mined, which is very labour-intensive." It is fascinating to stand on the edge of the pit and see how the project is progressing, says Nicole Schulz, who is continually on-site.

A total of 45 people are working on this project - including construction workers, planners and environmental officers. The latter, for example, check that the soil has not been damaged by the construction. “We care about the environment. This is one of the reasons why this project is finally being implemented,” emphasises Nicole Schulz.

Once the construction work has been completed - which is expected to be the case at the end of the year - the electronics will be installed. Electronics is necessary for the operation of the pumping stations work, to operate valves and to report any technical problems to the Centras maintenance unit. "In the event of an accident, a message would be sent, and the pipework will be blocked so that the environmentally hazardous substances can be extracted," says Schulz. The system should definitely come into full operation after half a year of testing with the built-in electronics.