Last Aug. 12, fire broke out at a Chester County chemical-storage facility owned by Chemclene Corp.

One of 378 Superfund sites in Southeast Pennsylvania and South Jersey, it had much in common with the Wade dump. Tanks on the five-acre property in East Whiteland Township held poisonous and volatile chemicals, and the groundwater was polluted with some of the same types of toxins.

Any resemblance to the Wade fire, however, ended there.

Within minutes of the alarm at 5:50 p.m., a detailed plan for handling a crisis at Chemclene kicked in.

Nationwide, tens of thousands of customized emergency-response plans have been drawn up for sites known to contain hazardous materials. They are part of a program mandated by Congress to protect the public and to warn firefighters of what they are facing.

The motorist who spotted the Chemclene flames had mistakenly reported a next-door address. When firefighters realized the error, they reached behind the front seats of their trucks - into a mini-library of notebooks.

There they found a map of the site; a list of its chemicals (including two suspected carcinogens); the environmental and health risks; the chances of explosions and toxic fumes; and advice on whether foam or water should be used. They were told to wear full protective gear and breathing apparatus in contaminated "hot zones."

Also by the book, they threw up barriers to keep tainted runoff from a nearby creek, and monitored air quality and wind direction. As the smoke thickened, residents in 80 nearby homes were evacuated until the fire was controlled about 9 p.m. The cause was not determined.

For the last six years, Chemclene has been in the business of selling and distributing hydraulic oil and solvents. From 1952 to 1993, however, it reclaimed industrial solvents; until 1976, according to the Environmental Protection Agency, Chemclene dumped some of those wastes on the ground.

The site has been on the Superfund list since 1983. But only last September, the 35 companies that produced, sold or handled wastes there before 1993 agreed to pay EPA $15.5 million for a cleanup, to begin soon.

Emergency plans such as the one for Chemclene arose from catastrophe: the deadly chemical release from a Union Carbide plant in Bhopal, India, in 1984, and a subsequent release from another Union Carbide facility in Institute, W.Va.

In response, Congress amended the Superfund law in 1986 to require companies to report the location of hazardous chemicals. From that data, state and local governments were expected to craft site-specific crisis plans.

Every county in Pennsylvania and New Jersey has them.

Chester County's database covers 94 sites, from light-industry to sewage and water treatment plants, where chlorine is stored. To that collection, East Whiteland Township has added emergency plans for more than 60 locations within its borders.

Should a fire or accident occur at any of them, specialists are immediately summoned to assist firefighters. Pennsylvania has 43 state-certified "haz mat" teams, six of them based in the five southeastern counties. Each of New Jersey's 21 counties has at least one team.

As team leaders raced to Chemclene, they used laptop computers to tap into federal safety data not in the firefighters' notebooks.

The fire trucks soon will be equipped with computers, too, said Kenneth Battin, East Whiteland's director of codes and life safety. Then "we'll be able to plug into a cell phone and connect directly to the Internet."