Ironically, one of the highlights of boomershoot in years past has been the "cleanup" part of the event. This traditionally took place after the main event, to clean up any remaining targets that had been missed by the shooters. People would take their semi-auto rifles to point-blank ranges and detonate any remaining targets from there.
Demand for this event was high. There weren't enough targets, so Joe started making more targets designated specifically for cleanup. And he started charging for participation. In 2009, Joe reached the final stage in the evolution of the "Cleanup" event: it is now a separate event held on a separate day only for those who pay, and doesn't really have anything to do with cleanup at all... so he renamed it the High Intensity Event.