Use hot water. Hot or warm water is the most effective way to melt snow. Connect a faucet to hose connect on a faucet in the house. This device enabled a hose to be connected to an ordinary faucet. Turn on the hot full blast. Spray the big snow pile with hot water and watch it melt. Within minutes the snow pile should be reduced to a puddle.
Cover the puddle immediately after with a mix of salt and sand. This will prevent the melted snow (water) from being turned into ice. Use liberally.
Use Ice Melter. Ice Melter is a mix of calcium chloride and sodium chloride that can be used instead of water to melt the snow pile. Cover the entire pile with Ice Melter and it should reduce the size of the pile considerably. Use copper sulfide if you can find it. Copper sulfide will cut through the snow instantly and work just s effectively as hot water. However, it is not something that is sold at most stores.
Contact the city. If the snow pile is on your property and it poses a safety risk, the city should remove the pile free of charge.