SCRAPER OPERATOR WAS HAULING MATERIAL INTO FILL AREA. OPERATOR WAS WEARING HARD HAT AND SEAT BELT. HE DROVE INTO FILL AREA AND WAS BUMPED UPWARDS CAUSING IMPACT WITH TOP OF CAB. AFTER MEDICAL EXAM IT WAS DETERMINED THAT THE OPERATOR HAD A CERVICAL SPRAIN. RELEASED FOR WORK A WEEK LATER.