The city of Hopewell, just downstream from Richmond on the James River, was the scene in the mid-1970s of a major environmental disaster, the illegal discharge into the river of thousands of pounds of the pesticide Kepone by the Allied Chemical Co. It was only last July that Virginia lifted a five-year ban on most fishing in some sections of the Kepone-degraded James.

One of the results of the Kepone case was the construction, largely with federal funds, of a huge new sewage treatment plant for Hopewell. Ninety percent of the plant's capacity is devoted to treating the wastes of five major industrial plants, including Allied Chemical and Continental Forest Industries, a paper manufacturer.

The plant was put into operation with an Environmental Protection Agency permit that specified just how much of what kind of pollutant could legally be discharged into the river. Subsequently, Hopewell and EPA signed a consent decree setting out fines for specific permit violations. Last week U.S. District Judge D. Dortch Warriner ordered Hopewell to pay a $1,600 penalty for exceeding in September the allowable discharge of suspended solids.

The city argued it was not subject to the fine, both on technical legal grounds and because, it said, the permit violation was beyond its control. A replacement part for a critical pump was late in arriving, the city said, and Continental Forest Industries released more waste for treatment than was expected.

Hopewell officials are deciding whether to appeal, according to attorney John A. Gibney.