THE PILOT LOST DIRECTIONAL CONTROL OF THE AIRPLANE WHICH COLLISED WITH A SNOWBERM AFTER LANDING WITH INOPERATIVE LANDING AND TAXI LIGHTS ON A DARK NIGHT. THE AIRPLANE TOUCHED DOWN ABOUT 20 FEET LEFT OF THE CENTER OF THE RUNWAY, WITH THE LEFT MAIN WHEEL 2-3 FEET FROM A 2-3 FOOT DEEP SNOWBERM ALONG THE LEFT SIDE OF THE RUNWAY.