In 1991, Hurricane Bob knocked out the power to Building 257 for several hours. At that time, PlADC's electrical power lines were above ground. Those lines now are below ground and thus impervious to storm damage. The Center keeps 400,000 gallons of fuel oil on the island to power this backup system. The discharge water quality is tested at least weekly and sometimes daily.
Plum Island has an excellent record for biosafety.
Even if one aspect of the system were to fail, the others are there to prevent any problems. While air handling and other systems prevent any viruses from getting out of the laboratory building, eliminating the deer that swim to the island ensures that they don't carry anything back back to the mainland. Also, deer are the main carriers of ticks that spread Lyme disease. When viruses are handled inside the current BSL-3 laboratories, they're only handled inside a biosafety cabinet that is equipped with special air filters and directed air flow to prevent the virus from getting out into the laboratory. The air handling system is monitored visually by employees, but also is monitored electronically.