With hurricane season approaching, and the memory of what senior living communities experienced with Hurricanes Katrina and Rita still fresh on everyone's minds here at the annual convention of the Assisted Living Federation of America (ALFA) in San Diego, conference attendees took part in a session on crisis planning and management yesterday.  While many senior communities will never experience a hurricane, all communities face the possibility of smaller-scale, yet very serious, crises such as fires, storm destruction, missing residents, and more.  Studies show that as many as half of assisted living communities don't have a formal crisis plan.  One company that does have a plan, and it's among the best, is Merrill Gardens, the Seattle, Washington-based company that operates 67 communities.  Its corporate communications director, Loree Wagner, served on the panel for yesterday's crisis session, and afterward, she talked with the Goldman Mature Market Report about the detailed crisis management booklet her company developed in 1997, just four years after the company's founding.