Which of the following is NOT a way for an operator to minimize their environmental impact while using a dumper?

The choice that does not contribute to minimizing environmental impact while operating a dumper is frequent refueling. Frequent refueling can lead to potential spills or leaks, which can harm the environment. It also means that the machine is being operated less efficiently, as it may not be utilizing fuel optimally during operations between refueling.

On the other hand, efficient use refers to operating machinery in a way that maximizes productivity while minimizing fuel consumption, thereby reducing emissions. Low engine speed can help in reducing fuel usage and emissions, as operating at lower revs typically consumes less fuel. Preventing spillages of fluids ensures that any hazardous substances do not contaminate the surrounding environment, which is crucial for minimizing environmental impact. Each of these other strategies is a proactive approach to reducing negative effects on the environment during dumper operation.