Disclaimer: I can only skim the surface of various highly complex rules I mention below.

Also, personally, I like solid surface counters.  

Is your ground already hard surfaced?  

We do still bury this waste so it's never on the surface of the ground but it's 100% safe and legal to dispose of that way.

It's a drainage ditch. 

However, their 38 page Prop Mgmt Agreement for OneRate is daunting--it lists many exclusions to their obligations such as any damage caused by force to a surface (whether from tenants, animals, roots, wind or other force of nature, etc).

If it is surface mold (and non-toxic), you can try bleaching everything and keeping the dehumidifier running. 

Make sure you have well water covered, rock roads versus hard surface.  

Water table is high due to these rain water drainage issues.

While this might seem fair on the surface, it may not accurately reflect each tenant's actual water usage.Usage-Based Billing: Implementing a system where tenants are billed based on their actual water consumption could be fairer.