The Pine Bluff Arsenal is to run an evacuation exercise Wednesday to practice its response in case of an emergency. The arsenal is preparing to begin destruction of its stockpile of chemical weapons, including nerve gas and mustard gas. The arsenal exercise will begin at 8:30 a.m. with sirens that will signal a simulated accident. Also, in an unrelated event, emergency planners are to test sirens in Jefferson and Grant counties on Thursday. Those tests will be between 8 a.m. and noon. The tests will be to evaluate a new siren system. Officials say residents who hear the sirens during the drills Wednesday or Thursday should not be alarmed.