Man vs. Sea: Machine Control Changes the Tide

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The Scheldt River is the most important waterway in Flanders, Belgium. The river and its tributaries define the landscape and are considered the engine of the regional economy. One of its most important roles is being a major transportation route feeding the port of Antwerp, Belgium. Additionally, the Scheldt River basin offers recreational opportunities for its many visitors.

But this part of the world is well known for its storm surge and consequential flooding. Like generations before, the people of Flanders and Holland are faced with monumental water management challenges.

A successful solution requires a large scale, united effort with cooperation between two countries as well as several large construction and dredging companies. The companies are using 3D machine control because the technology provides the ability to better address complex project designs. This enables the designs to be built more productively and more accurately. Several brands of 3D machine control systems have been used on the project. These are listed toward the end of the article.

The History
Year after year the tides have been rising, further eroding the disappearing flood plains. This deepens the Scheldt and straightens its once curvy banks. In 1953 a huge storm tide caused the Scheldt to flood its banks, causing significant loss of life--1853 fatalities-- in The Netherlands and in Flanders. Damming the river completely has proven to not be a solution.

On January 3, 1976, again there was a huge, northwesterly storm and again the dikes could not hold back the water. The entire Seascheldt basin was flooded. In Antwerp, the water rose 7+ meters, 3.5 meters higher than the average high water levels. While there was only one fatality (one too many) the property damage was extensive. (Leo Clinckers, Waterwegen en Zeekanaal NV)

The Plan
To avoid future disasters, a large and ambitious project--The Sigmaplan--was created shortly after the 1976 storm to handle future flooding potential. In addition to the Scheldt basin, this plan was designed to protect the river and its 6 tidal tributaries (which total over 250km of tidal rivers).

A combination of high storm tide and wind direction causes a huge amount of water to flow into the Scheldt basin. With each surge, the water velocity increases. To decrease and manage the incoming water via intentional flood plains or control areas, the original Sigmaplan positioned new dikes at 13 locations with the objective of storing the water in these new flood plains.

Traditional engineering would have meant for higher dikes and dams, yet Flanders officials chose a new approach to not only strengthen its existing dikes but to lower them as well. The lower flood-able dikes allowed the waters to spill over the top, relieving the immense pressure that compromised previous designs. Another set of taller dikes-- called ring dikes--was built further inland. These ring dikes protect villages from flooding. The area between the two dikes serves as a holding or control area. This approach, like the oak tree and the sapling in Aesop's Fables, bends with nature rather than trying to stand against its force.

Now, after 25 years, the original Sigmaplan has been revisited. Climate change, rising sea levels and ongoing construction of the riverbanks are impacting the evolving design. With all of this data, new insights and technologies are being implemented, broadening the potential benefit of the Sigmaplan. Of course, the safety aspects were always a goal, but it was felt the river could also serve the environment and the recreational needs of both residents and tourists. (Wim Dauwe, Waterwegen en Zeekanaal NV)

To nurture the new tidal areas, an inlet sluice was installed into the lower flood-able dyke allowing water to flow into the flood plains in a controlled, simulated ebb. The flow is via the outlet sluice, again simulated. This simulated ebb and flow via inlet and outlet sluice nurtures the mudflats and salt marshes, and uses less land.

In the Flood Control Area in Kruibeke-Bazel-Rupelmonde they are finishing this kind of construction. In the (smaller) project area HammeLippenbroek an inlet- outlet construction is already in use. All of the projects are part of the Sigmaplan.

With seawater slowly mixing with the river water in the Scheldt basin, a unique ecosystem is created in Western Europe. But with the passing years, large parts of the natural tidal surroundings have disappeared. The new Sigmaplan is designed to protect the entire Seascheldt basin against flooding and at the same time, creates room and opportunities for the restoration of different types of nature, including tidal nature. With the new ebb and flow, mudflats and salt marshes will have opportunities to rise again. (Lieven Nachtergale, Agentschap voor Natuur en Bos)

Hedwige-Prosperproject
The Hedwige-Prosperpolder Project is also a subset of the new Sigmaplan. The area covers 465 acres, of which 170 acres are in Flanders. This project is designed to transform the Dutch Hedwige-Polder and the northern part of the Flemish Prosperpolder into a cross-border tidal area. This means that during flooding, water will flow there twice a day at high tide. At low tide, it will empty again.

The images below illustrate the original land before the HedwigeProsperproject as well as the future low and high tide. The complete project on the Belgium side is 1,200.000 M³. The Dutch part, which hasn't yet started, is roughly 1,800.000 M³. Peter De Moor, Survey Development Engineer at Dredging International states, "The Belgian portion of the project started four years ago. This is because the Belgian government needed to deliver the material (normal ground, clay, etc.) as it became available." Peter drove me out to the current project to explain the progress and adds, "This is a temporary job of 400.000M³ which started up in mid January 2012 and needs to be finished by mid March 2012. Frost (temps down to -15°C!) and snow created an extra problem for us with heaps of mud making it very difficult for our dumper trucks to operate." (I can personally attest to this because the vehicle Peter and I were in got stuck and we had to be pulled out.) Peter continues, "The 400.000M³ of earth placed for the current project will be reallocated in about two years becoming a part of the bigger project."

Collaboration
The project is being executed by a joint venture between three Belgian-based companies:
1. Dredging International www.deme.be (www.decloedt.be | www.dredging.be | www.tideway.nl www.geosea.be)
2. Jan De Nul (they have also dredging activities and road construction) www.jandenul.com
3. Aertssen (one of the biggest dry works companies in Belgium) www.aertssen.be

Machinery and system breakdown
1. Dredging International: 2 excavators using Carlson Grade, 4 excavators without GPS, 2 automatic dozers and 1 indicate dozer (all Carlson Grade/ MOBA Controls), 11 dumper trucks
2. Jan De Nul: 2 excavators (one with Qinsy (QPS) system and one with
Leica MC) 4 without GPS, 1 dozer without GPS, 4 dumper trucks 3.
Aertssen: 2 excavators with Topcon MC and 2 dozers with Trimble MC. Also 5 dumper trucks

Besides these three larger companies, there are a few other companies, which have in total 2 excavators, 2 dumper trucks and 3 tractors on the job. Currently none of these machines are utilizing machine control.

Again, Peter De Moor, "In addition to hooking up the GNSS rovers for these machines to one RTK base station (Septentrio AsteRx GPS/Glonass), we had other issues regarding the surfaces files. All parties need the design information and change orders to be in the format of their specific 3D machine control system. Some data needs to be available in DXF or DXF 3D spline format, others in ASCII. This is a real problem for us."

Looking Forward
As Peter stated, when several brands of 3D machine control systems are used on a large project, additional challenges with regards to data flow and RTK correction are encountered. An optimal consideration would be for all machine control system manufacturers to sit together and search for a universal exchange format. Such a format would minimize time loss created by file incompatibility. Currently, part of the time won by the use of machine control is lost due to extra work in converting files, although the overall benefit is there.

"This problem isn't unique to only this site. This will happen on future huge reclamation sites," continues De Moor, "Sites like the New Doha Airport site in Qatar, for example, is a land reclamation project of 65.000.000M³ to be completed in a period of 3 years. One company alone could not have executed this. For a couple of weeks we moved 600.000M³ per week!" These giant endeavors are nearly always a joint venture due to machine shortage, or an attempt at spreading financial risk between multiple companies. 

Large projects, such as The Sigmaplan, cannot be completed easily without the use of 3D machine control on the finishing machines. There are hardly any straight lines. Putting up lasers or sticks isn't a solution either. The terrain, especially for the Belgian project, is near impossible to work on. GNSS is the best solution. But standardization opportunities for technology providers do exist. Such standardizations would greatly streamline workflows productively simplifying project lifecycles.

Randy Noland is the Managing Editor and Co-founder of Machine Control Magazine.

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