Stopping the discharge as soon as possible is the most important step. This is where local fire departments and local industry response teams, often first on-scene, are invaluable. As long as it is safe to do so, a trained person on the scene can close valves, plug or patch holes, or transfer the contents of a leaking container to a sound one. Using materials close at hand such as wooden plugs or rags to stop or slow a leak is often more effective than more elaborate methods which may take a while to obtain or install. No attempt should be made to stop a leak if undue risk is involved.
Many chemicals require special handling, equipment, and procedures.
If the equipment or knowledge is not at hand, you should wait until the necessary help arrives. Failure to do so could result in personnel casualties, fire, or explosions, and could also make the spill worse. Containing the spill and stopping its spread should immediately follow or be concurrent with stopping the leak. Responders may employ several methods to contain the product spilled on the ground, such as building a dike around it, plugging or otherwise protecting all storm drains or sewers in the area, and diverting product into a ditch that can be dammed. This figure shows how to protect a curb-type storm drain by diking or booming.