Catch basins (or storm basins) are primarily used to collect pavement runoff and act as a junction for a storm drain system. They are constructed with a sump below the pipe invert. The sump collects sediment and debris entering the catch basin through the grate inlet. The collected material is typically removed by hand or by the use of a vactor truck.
Once the asphalt perimeter of a storm basin has been removed, the base is excavated as deep as is necessary to perform the adjustment.