Are you building a wood drop in or just piling up snow?  Since it's winter, make your drop in out of snow.  If it's not fast enough, make it bigger and/or spray water on it to ice it down. All this takes it a shovel and spray bottle of water.  Make sure to spray tranny and lip too. I build one in my front yard every winter and mine always ends up being about 5 foot tall.  Works great.