Givens
Area: 40,000 sf
Weight of average snow: 15lbs / cubic foot
Heat of fusion: 144 BTU
Specific heat of ice: .51 BTU / f
Average (Jan.) nightly low, NYC: 26f
Melt slab efficiency: 50%
Assuming we want to melt a 1' snowfall in 3 days:
Total snow = 40,000sf * 15lbs = 600,000lbs of snow...