The maintenance of waterways is expensive. Optimization of reconstruction projects can save money and limit hindrance for the public. In this presentation I show how the implementation of Spatial OLAP can give better insight in the quality of the construction of waterway banks. By spatially overlaying inspection results with construction records, a better estimation can be made about the overall quality, potential danger and repair costs. Spatial OLAP is an excellent way to provide insight into the different variables involved in the planning proces of maintenance.