Spectacular drill head squeezes sewer under Oosterring in Genk

During the construction of a new collector sewer by Aquafin from Zutendaal to Genk-Zuid, a spectacular phase will start from Monday 30 September. A drill head with a diameter of no less than 2.5 metres will press the sewer pipe under the Oosterring. Not only the size of the pressing, but also its drive by mains electricity instead of environmentally harmful diesel generators, makes this construction site unique.

Aquafin is laying the new collector sewer to replace the existing pipeline that is in poor condition. The wastewater from nearly 10,000 residents of mainly Zutendaal and part of Genk finds its way to Aquafin's sewage treatment plant in Genk via this sewer. "The old collector is in such bad condition that it needs to be replaced. Because it is located at great depth under the industrial estate, the works for a replacement at the same place would cause too much disruption to the companies," explains Niels Hermans, project manager at Aquafin. "It was therefore decided to construct the new collector a few hundred metres further parallel, under a service road of the regional road. The old collector will remain in service until the works are completed and will then be decommissioned."

The new collector will be 6 metres deep and should cross the Oosterring. Contractor BESIX Infra is carrying out the works on behalf of Aquafin and is working with Tijdelijke Maatschap Smet Tunneling -Kboringen for the jacking of the collector. "A bore with a 2.5-metre drill head is rather rare in Flanders and absolutely spectacular to see. Today, the drill head arrived and was lowered into one of the two deep construction pits previously prepared by Smet Group. The actual drilling will start from tomorrow and take two to three weeks," says Tom Jamaer, project manager at BESIX Infra.

Fixed power = reduced emissions

Needless to say, a bore of this calibre requires some power. Usually, diesel generators are used to provide the necessary power. In this project, Smet Group opted for a temporary connection to mains power with an electricity cabin on site. This avoids the emissions from diesel generators, estimated at 1,200 tonnes of CO_2, for this yard. Wouter Roels, area manager of Smet-Tunnelling: "The construction industry is responsible for about 40% of global energy consumption. Most emissions on construction sites come from burning diesel fuel. We feel it is our duty to look for alternatives and this can be done, for example, as here, by opting for solid power. That way, we can reduce our carbon footprint." Being powered by mains electricity also avoids noise pollution

Reuse of residual product

A sustainable solution was also considered for the water use to carry out the drilling. Tom Jamaer, BESIX Infra project manager: "This technique uses a lot of water. Drilling releases bentonite sludge, a residual product that is usually disposed of for processing. As large quantities are involved here, we chose to dewater this sludge on site as much as possible. The residual water is reused for drilling and the residual product is used as filling material to refill the trenches created. Both ecologically and economically, this is the most sustainable option."