Bad Tenants storing trash/waste on property

[Greg Dyer]

My father-in-law recently had tenants break contract and leave early. Among many other issues, we found that instead of paying for a trash pickup service, the tenants had been storing all their trash in the barn on the same property. Is this illegal in and of itself, in addition to violating the signed contract? What legal options can my father-in-law pursue at this point?