Cooking outside in a coal pit requires special precautions you would not need to undertake with other cooking methods. Using a stove or gas barbecue grill only requires you to turn a knob to turn off the fuel source, but with coals, unless they are properly extinguished, hidden embers could reignite and start an unattended fire that could easily spread outside of the pit. Avoid disaster and ensure your coal pit fires are completely out before leaving the area.
Suffocating the fire of any oxygen source will extinguish the flames and any glowing embers. For large pit barbecue grills, close all the vents and put the lid on to keep oxygen out. For fire pits in the ground used to barbecue, cover the pit with a layer of sand. Wait for one hour before checking the coals for any burning embers. The amount of time required for the fire to go out will depend on the amount of coals used and the size of the pit. Use this method if you have a small pile of coals and the time to check the coals an hour later.
Spraying the coals with water will generate a large amount of steam, but the water also acts to keep oxygen from getting to the coals to keep them burning. Stand back while spraying the coals to keep away from the hot steam rising. Use a fine spraying mist with a watering can or garden hose, and stir the coals with a long, fireproof stick to ensure that all the coals have gotten wet, which is especially useful for quickly extinguishing large coal pit barbecue fires.
For a thorough method to ensure every single coal is extinguished, submerge each one in water, which can be used as a secondary method for any other method to ensure that there are no more embers in the coals. Wait until the coals have died, and transfer them from the pit individually to a large container of water. Remove the soaked coal to a nonflammable surface to dry before storing in a fireproof container. The dried coals can be reused if you add a squirt of lighter fluid to get them started next time.
Should a large flare-up occur, you will need to have on hand supplies to control it. Always keep a fire extinguisher nearby when using any type of barbecue pit or fire to use if the flames escape the pit. Keep a small spray bottle of water on hand to reduce the flames from grease dripping onto the hot coals. For larger flames, pour baking soda over the fire to extinguish the flames, which will ruin your food but will save the rest of the area from catching fire.