By P.J. Heller Nine decades after “Grandpa Sol” started his business by repurposing wood waste materials, his legacy lives on.  “We’re doing the same thing 90 years later that grandpa did in the ’30s,” says his grandson, Rusty Rexius.  Grandpa Sol’s business – Rexius Fuel Service – initially involved going to Oregon sawmills to collect sawdust, which would normally be …