One point of contact for all inspection and monitoring work

The area around the Markermeer dikes is characterized by a very weak subsoil. Extreme care must be taken when reinforcing the dikes to keep settlements to a minimum. That does not alter the fact that the surroundings and adjoining buildings are being closely monitored by independent inspection and expertise agency Van Monsjou & Partners. 

Already since 2015, Van Monsjou & Partners has been taking half-yearly measurements of all properties (elevation marks) along the 33-kilometer stretch on behalf of Alliantie Markermeerdijken. "This involves a total of 450 properties and 1,800 height marks that have been installed in the past," says Sander van Monsjou. "We are widely versed in monitoring work and can take elevation measurements as well as
perform vibration measurements and structural preliminaries. That combination means the Alliance has only one point of contact for the inspection and monitoring work around the project."

Deviant behavior

"By starting measuring the properties at an early stage, the normal course and settlement behavior is charted over a longer period of time," Van Monsjou continued. "This provides a good picture of which properties are more or less susceptible to settlement, which is important for implementation. In 2019, we then started performing structural preconstruction surveys in accordance with the BRL 5024. As a company, by the way, we were at the cradle of this guideline, which is now required by more and more clients and has gradually become standard."

Since the Alliance has been operating outside, Van Monsjou & Partners also provides deformation measurements. "In properties near the works, elevation marks and/or prima's are installed. Through regular measuring, the position/position in three directions (x, y and z) is monitored," Van Monsjou explains. "Finally, we also provide vibration measurements to monitor the impact of the work and traffic on the properties. Those measurements are immediately visible to the Alliance in an online portal. If a test is carried out to know the impact on the surroundings, and that happens regularly, you see the result immediately and the implementation method can be adjusted if necessary."

Van Monsjou & Partners is registering the environmental impact of the dike reinforcement task. "The Alliance is proceeding extremely carefully in this regard so that immediate action can be taken should a boundary be crossed somewhere. It is also a dynamic and extensive project for us," Van Monsjou acknowledges. "The Alliance is active on several dike sections simultaneously and not infrequently we are called upon ad hoc to perform a measurement or place a vibration meter. That makes the project very exciting, quite apart from the beautiful surroundings."