— The longest surviving engineered structure has existed for less than half the time it takes for many nuclear wastes to decay. This pyramid was built of stone and has rested in a seismically stable and arid region of the world. However many operating metal mines store their mining wastes behind giant earthen dams in wet and seismically active regions. Even less protected are coal combustion wastes which are currently stored in old mines, pits, and shallow lakes with little or no regulation.
