ACH500 were a work horse. The caps are typically designed for 20 years as long as they have power applied. There is no worry of them drying out then. Looks like an internal failure caused the boom. Sorry for your loss..
would have been better if the critters in question were the ones from 'Tremors'
"Once men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them."
- The Reverend Mother Gaius Helen Mohiam