We all run across mattresses that have been improperly disposed of. They do not belong on the side of the road, at the bottom of a lake, or in a field somewhere. You must dispose of your mattress in a safe and responsible way--a way that won't cause harm to the earth, or make your old mattress someone else's problem.
If you are getting rid of your old mattress, you must have a new one! Ask the store where you have purchased your new mattress if they can haul off your old mattress when they deliver the new one. Some places do this for free and some may charge a small fee.
Ask your local trash service if they can dispose of the mattress for you.
You can also use Google to try and find new ideas. It's important to dispose of them properly.
Call Bin There Dump That for all your dumpster needs!