Basically, a catch basin is a bucket sealed around the fill pipe. To protect against spills, the basin should be large enough to contain what may spill when the delivery hose is removed or uncoupled from the fill pipe. Basins range in size from those capable of holding only a few gallons to those that are 30 gallons or larger. The larger the catch basin, the more spill protection it provides. You need a way to remove liquid from catch basins.
Manufacturers equip catch basins with either a pump or drain to remove liquid.
You should try to keep water out of catch basins. Some catch basins can collect enough water and sediment, along with spilled product, to make draining this mixture into the tank unwise. If this happens, you may pump out the catch basin and dispose of the liquid properly. If the liquid contains fuel or chemicals, it could be considered a hazardous waste. Contact the Wisconsin Department of Resources, responsible for hazardous waste, for information on handling and disposal requirements.