The contractor has to dewater to dig an excavation for an electrical duct bank-the water table is high. The soil is mildly contaminated so all of the water has to be treated in a Chitosan-enhanced Sand Filtration (CESF) system with granular activated carbon (GAC) before discharge to the waterway. The contractor set the well points, hooked them up to the pump but not the CESF system. So, water went directly onto the ground from the pump and into the nearest catch basin. The foam is from the silt in the soil that has been aerated by the pump.