EE WAS ATTEMPTING TO LOAD WATER TRUCK. WYHEN HE TRIED TO OPEN VALVE TO LET WATER FLOW IT WOULD NOT OPEN. EE THEN JUMPED UP TO GRAB ROPE ON VALVE TO PUT ALL OF HIS WEIGHT ON ROPT, ATTEMPTING TO FREE STUCK VALVE. WHEN VALVE CAME LOOSE, EE HIT GROUND (LANDING ON HIS FEE) AND FELT SHARP PAIN IN HIS BACK.