Lab tech was taking out trash at the end of the shift. When EE threw a 2 gallon bucket of clinker(<20 lbs.) in the side door of an eight yard dumpster, EE felt a pull in the left side of EE's stomach. EE was taken to the ER for medical evaluation, placed off work until a follow up with regular physician, when EE was placed on restricted duty. 1 day LT, 10 day RD