NETHERLANDS: With major flooding predicted in the next 25 years, the Dutch rely on sturdy defenses against rising sea and river levels
by Nigel Griffiths
O ver the centuries, the Dutch have become the world’s leading experts at reclaiming land from the sea, building flood barriers known as dykes to prevent flooding and using windmills for drainage. But their elaborate flood defenses are once again under threat as climate change causes sea levels to rise. The authorities are taking early action, and customized Volvo excavators have been deployed to help strengthen the country’s flood protection.
With so much of its territory reclaimed from the sea, flood control has always been an important issue in the Netherlands. Today, some two-thirds of the country is vulnerable to flooding, the consequences of which could be devastating in such a densely populated region.
A complicated system of drainage ditches, canals and pumping stations (historically windmills) keep the low-lying parts dry for habitation and agriculture. But it
is no longer enough and, believing it is just a matter of time before disaster strikes, the authorities are busy strengthening their flood defenses.
Specialist environmental and dredging engineers de Vries & van de Wiel, a subsidiary of the DEME group which has been engaged in dredging and land reclamation in the Benelux since the middle of the 19th century, have designed a flood protection project for one of the main danger points. Their contract involves complete responsibility for design and construction of water defenses as well as total environmental management of the area and relations with local populations.
Working with six Volvo excavators – two EC380EL, two EC250CL models and two EC220DL machines – the machines have been specially customized for de Vries & van de Wiel by Volvo distributor, Kuiken NV.
Of immediate concern to the Dutch authorities are the rivers – the IJssel, Meuse and Waal are all offshoots of the powerful River Rhine. The ‘Room for the River’ project is an integrated spatial plan launched in 2006 for flood protection and environmental management. It involves building or modifying dykes, deepening flood channels and creating flood plains to serve as a flood bypass.
Along a stretch of the River IJssel between Cortenoever and Voorsterklei, a major bend in the river already features a flood plain, ancient dyke and historic farms. The river is narrow and has strong currents, fed by the surging power of the Rhine. With rising sea levels, major flooding is predicted within the next 25 years, with the impact on the surrounding areas expected to be devastating. The last major flooding in the area was in 1990 and the authorities know what to expect.
For this area, de Vries & van de Wiel plans to give the river more room to try to avoid catastrophe. The project, which runs until March 2016, entails building a new dyke 1km further away from the river. The existing structure will be lowered to become a primary barrier during normal conditions. The river is being widened and dredged to lower the water level by 30cm, creating additional space within the flood plain to cope with flood water.
The contract with de Vries & van de Wiel gives the company complete responsibility for design and construction of water defenses as well as total environmental management of the area and relations with local populations.
“At de Vries & van de Wiel we needed equipment which could work on different types of projects ranging from dyke building to dredging from pontoons,” explains technical superintendent Nanco Klein. “We need the machines to operate for 2,200 hours a year to be economical. This means they must be able to carry out a variety of tasks on both land and water.”
The challenge for Kuiken was to find the optimum mix of features that would permit de Vries & van de Wiel to operate cost-effectively in its different working environments,” explains Ger Kleine, business line manager at Kuiken.
The customized Volvo machines provide the extra reach needed for both building the dykes and dredging, two completely different applications that involved special modifications by Volvo CE to extend the machine booms and arms. Each excavator boom can be extended from 6.45m to 8m, while the arm was extended from 3.20m to 4.70m. To compensate for the extended boom and arm is a cleverly designed additional 2,300kg counterweight.
One EC380EL has a hydraulic cab riser, which can elevate through 1,700mm for better visibility when maneuvering over angular dykes. Dredging requires a high level of precision and sensors fitted around the machine give the operator a 3D view of digging or dredging on the cab’s computer screen.
Other customized features include pressure alert sensors, pressure filters, quick-coupler hydraulic connectors, an 18-tonne load hook, and customization for underwater operation. The excavators have wide 900mm track shoes for better support in the soft Dutch clay.
One of the more unusual customizations requested by de Vries & van de Wiel was to replace the Volvo yellow with the company’s green livery. The booms are painted grey for practicality, explains project manager Richard Moens, as it avoids reflections that could impede the operator’s work.
When selecting equipment, de Vries & van de Wiel thinks long term, Nanco explains. “High standards on emissions compliance are being specified by the government and we expect these to rise further,” he says. “We are investing with a minimum five-year perspective, and we want to ensure we are at the highest level for performance and emissions compliance.
“When selecting a machine, our calculations are based on the cost of ownership over a five-year period. Indeed, fuel costs over five years are three times the investment in the machine, and service and back-up are also important,” Nanco adds. “At the end of the day, we have excellent excavator platforms for multiple uses with powerful engines and low fuel consumption.”
Another important factor in winning the de Vries & van de Wiel order was Kuiken’s support capability. The company has service vehicles across the country and can even deliver parts overnight. Kuiken’s Kleine explains that de Vries & van de Wiel has no in-house maintenance facility. “They have one planner for the Volvo fleet who can monitor the CareTrack telematics system,” he says. “This gives them a good insight into operating efficiency, plus facts and figures on the cost of the work in progress.”
As work advances, farms have been relocated beyond the new dyke although agricultural activities will continue. Dyke modifications are carried out with respect for the natural environment, and plant species and birdlife are being maintained. Working closely with local residents, de Vries & van de Wiel is also helping find solutions for homes and businesses affected by the project.
As a finishing touch, a cycle path is being built along the top of the dyke to provide recreational opportunities, while the reinforced Cortenoever flood plains will help give residents both peace of mind and protection from the elements.