The Reagan administration yesterday made a major move to enforce the cleanup of hazardous waste dumps by suing 16 firms and the owners of a large dump in Hamilton, Ohio, and reaching a $2.4 million settlement with more than 100 other companies that used the facility.

Administration officials called the actions a model for dealing with the problem of poisonous waste disposal. The 10-acre Chem-Dyne Corp. site in downtown Hamilton was used to store hundreds of thousands of gallons of chemical and industrial wastes, including arsenic and PCBs (polychlorinated biphenyls).

Environmental Protection Agency Administrator Anne M. Gorsuch said the settlement is the largest voluntary waste cleanup commitment by industry so far.

In a statement, she called the number of companies participating "dramatic evidence of a new trend. We believe this is being engendered by EPA's approach of a willingness to negotiate, backed with a strong enforcement commitment."

The suit, alleging violations of the Resource Conservation and Recovery Act (RCRA) and the so-called Superfund law, was filed in U.S. District Court in Cincinnati against those companies that refused to take part in the negotiations. Among the defendants are Monsanto, B.F. Goodrich, Shell Oil, Georgia-Pacific and Phillips Petroleum.

A Justice official said it was the first suit the administration has filed under the Superfund law, which set up a $1.6 billion fund financed by industry and government to clean up hazardous waste sites around the country. Several earlier suits have been amended to add Superfund claims and defendants.

Michael Brown, the EPA counsel who supervised the negotiations, said he feels yesterday's action will "help stop resistance to future agreements. Hopefully it will lead to a pattern of negotiations, and assurances that if companies don't come on board we will take legal action."

Dave Linnett of the Environmental Defense Fund called the suit "a good sign," but added, "The fact that the administration has filed a Superfund case shouldn't be a cause for celebration. We've had to lower expectations because the enforcement performance has been so bad for the past 18 months." He attributed the administration's recent Superfund movement to "political pressure from everywhere. There's not a segment of society that doesn't think Superfund should be enforced."

The suit said the Chem-Dyne facility contains 11,500 55-gallon drums of chemical wastes, including PCBs, vinyl chloride, benzene, arsenic, cyanide and toxic pesticides, as well as 14 large bulk storage tanks. It is located near the water treatment plant for the city of 85,000, as well as near a hospital and several ballfields. It was the scene of a five-alarm fire in 1979. The site is one of the largest hazardous waste facilities in the country and one of the 160 targeted for priority action by EPA under the Superfund law.

The site was placed in receivership a few years ago after state court action, but agreements to clean up the dump have not been met, the suit alleges. The government already has spent $826,000 in emergency work on the site and EPA plans to spend $2.5 million more from the Superfund to clean up the dump if the companies charged aren't ordered to do so, the suit said.

The government asked that the court issue an injunction requiring a cleanup and that the defendants reimburse the government for past and future costs. Letters warning of possible liablity were sent to 289 users of the site last spring. EPA met with 46 of the largest users in late April, and talks began later.

Contributions from the firms that settled range from $5,000 to $250,000 by the Velsicol Chemical Corp., EPA officials said. Some companies decided to settle because their legal costs in a suit would have been higher, they said.

Mark Stanga, legal adviser for the Ohio state EPA, said yesterday that the state refused to sign one part of the settlement agreement that ensured the 100 firms they won't have to pay more for the cleanup, even if a federal court later finds that they didn't pay their fair share. "It was a concession by the federal government," he said. "It was a bargaining chip. The state has never done that." But EPA's Brown said the promise was necessary. "Otherwise there wouldn't have been a settlement."