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You may be able to get away with a 3hp (120V)electric motor and some gear advantage to reduce the load on the motor and reduce the speed of the motor, (typically 1800 rpm). These motors are commonly found on air-compressors and wood lathes etc. you will need significant lengths of extension cords in order to plug in to receptacles commonly found in/on parking lots/buildings. do not cheap out on extension cords. Small gauge wire will contribute to voltage drop which will lesson power. Also GFI protection will be desirable in the wet snow.
one of these, get somebody or yourself to weld a simple aluminum cube around it, find a pulley that will fit the output shaft and it should work. maybe.