EARLIER IN THE DAY, THE PILOT RECEIVED INFORMATION ABOUT THE LANDING AREA. HE UNDERSTOOD THAT THE LANDING AREA WOULD BE CLEARED OR PREPARED AND BE DEFINED BY FLARE POTS. HE BELIEVED HE WOULD BE LANDING ON A FROZEN RIVER. DURING ARRIVAL AFTER DARK, HE FLEW OVERHEAD TO LOOK AT THE LANDING AREA. FROM THE AIR, THE PILOT PERCEIVED THAT THE LANDING AREA WAS ADEQUATE AND HAD BEEN PREPARED BY GROUND PERSONNEL. ON SHORT FINAL, HE SAW A BERM ACROSS THE APPROACH END WHICH TENDED TO CONFIRM THAT THE STRIP HAD BEEN LEVELED OR PREPARED. THE PLANE WAS LANDED ON SKIS WITH THE WHEELS RETRACTED. AFTER TOUCHDOWN, THE PILOT SELECTED REVERSE THRUST TO SLOW THE PLANE. WHILE SLOWING THROUGH ABOUT 30 KNOTS. THE PLANE HIT A THREE FOOT FROZEN SNOWBANK AND WAS DAMAGED. THIS WAS THE PILOT'S FIRST LANDING AT THIS LOCATION. THE LANDING AREA WAS UNIMPROVED. ROLLING, SNOW COVERED TUNDRA WITH TEN INCH SNOWDRIFTS.