Hi, You do not say what is include in your current permit. Rock crushing presumably would involve dust suppression, perhaps with water. If there is an effluent discharge from this activity you may require permisson to discharge this element. Is there likely to be any other say airborne dust or emissions from this, again not included in your permit - these may require address. Spoil from the process, if any may have minimum storage times on site - you may have to hold a permit. Take an objective view of the process and investigate anything that may emit anything. Presumably you have all the planning requirements covered.