How to achieve a Good Dewatering and Cofferdam Process

There are a number of challenges that cofferdam and dewatering projects pose during the construction process. According to construction dewatering experts, miscalculation of what is below the surface such as depth and flow, groundwater infiltration and degree of turbidity may result in costly operating expenses.  Here are some important tips to consider.

Depth and Flow

According to groundwater treatment system experts, the depth and flow of conditions of rivers fluctuate depending on the season so it is vital to review the timing of the project. For example, water levels are usually lower in the Northeast in August compared to April after heavy rain or snow melting. It is always a good idea to check USGS gauges in order to monitor differences in river levels and speeds of flow so as to best gauge the most ideal timetable for a project.


It is vital for any contractor to know the limits of the permits they are going to get, as this will have a direct effect on the dewatering project.  Permits for turbidity, contamination, right of way and time constraints for working in the water are the responsibility of the project engineer usually but it will not hurt if the contractor also is aware of these as well.

Navigating the Subsurface

It is vital that contractors are aware of the silt levels, vegetation, slopes and the composition of the subsurface because all of these will have an effect on the kind of cofferdam method that will best be used for the project.  For instance, bedrock is not a good area to drive sheet piling while too much vegetation could establish waterways or channels beneath the subsurface that could potentially leech into the dry work area.  Having a good knowledge of the subsurface terrain as well as the elevations will play a crucial role in choosing the best cofferdam method.

Engineering and Design Criteria

The contractor must be able to know which dewatering solution or technology is best used for a certain project and if it is also ideal from a cost and viability point of view.  He should have intimate knowledge of dam safety protocols and other procedures to be able to provide adequate engineering support should there be an emergency.