EMPLOYEE STATED HE STOPPED AT TOP OF HILL, PUT TRUCK IN 2ND GEAR PRIOR TO STARTING DOWN. GOING DOWN THE HILL THE BRAKES STOPPED WORKING. AT THE #5 MARKER HE DROVE INTO THE STRADDLE BERM AND IN TO A SUMP. HE RECEIVED ON BROKEN RIB. WAS TOLD BY DOCTOR TO RETURN TO WORK IN ONE WEEK.