A trucking firm, whose Maryland terminal was the site of a chemical spill in March that sent 20 people to the hospital and forced the evacuation of 1,500 residents, pleaded guilty to charges filed today in a series of hazardous waste violations.

Matlack Inc., a large, long-distance trucking firm, was fined $125,000 by Anne Arundel Circuit Court Judge Martin A. Wolff.

The fine, the maximum penalty for the five charges, is the second highest for hazardous waste violations ever levied in Maryland, according to James J. Ryko, an assistant attorney general assigned to the state's Hazardous Waste Strike Force.

Prosecutors did not allege that any environmental damage occurred because of the violations at the terminal in the Baltimore suburb of Brooklyn Park.

"But hazardous waste is inherently dangerous," Attorney General Stephen H. Sachs said in a statement today, "and responsible companies should not have to wait until disaster occurs before bringing their operations into compliance with Maryland's environmental laws."

David B. Irwin, Matlack's attorney, attributed the violations largely to the complexity of rules and regulations governing the environment. He said he did not want to make light of the violations, but added: "We do feel they are somewhat technical in nature."

He said the company had cooperated with the state investigation and has already corrected the problems cited in the charges. "Matlack is very concerned about the environment," he said.

In March, the toxic chemical methyl acrylate leaked from a tanker at the Matlack yard, which is used primarily to wash the firm's tanker trucks that haul wastes. Residents in the area were evacuated when the liquid chemical, used in processing fabrics and plastics, began to vaporize. None of the 20 persons who were hospitalized suffered serious injury.

The charges filed yesterday do not relate directly to the chemical spill. But the spill prompted the state investigation into the facility.

According to the charges, company tankers were washed at the facility and the wash water, often containing hazardous materials, was pumped through the company's own waste water treatment plant.

On 17 occasions since 1983, according to a statement of facts presented with the charges, the company washed allyl alcohol from its tankers. Allyl alcohol, used in making resins, plastics and poisonous gases, is listed by state officials as "acutely toxic" -- the most dangerous category of toxins. It can cause severe irritation of mucous membranes and eyes, as well as liver and kidney damage.

Although Matlack was not charged with any violations regarding the March chemical spill, Lyko said, "the kind of violations that they pled guilty to are the kind of violations that create the climate that allowed the accident to occur . . . . Had the proper environmental safeguards been implemented up front, that type of thing may well not have happened."

The company did not have a permit authorizing the treatment plant to handle highly toxic chemicals, according to the charges, and the plant was incapable of treating many of them. After going through the plant, the wash water was pumped into the Anne Arundel County sewer system.

Concentrated residue removed from the wash water was placed in improperly sealed 55 gallon drums, some of which were stored at the facility without proper permits, according to the charges. The company did not analyze the residue, but on some occasions shipped it out of state under the label of "nonhazardous waste," according to the charges.