Weston, a demolition subcontractor, was hired to remove hazardous materials from tanks at a Superfund site. The contract required removal of all tank contents. When Weston encountered non-pumpable solids it couldn't remove, it claimed this was a differing site condition and sought extra payment. The court ruled against Weston, finding the contract clearly required removal of everything regardless of how it had to be removed. Subcontractors cannot use unexpected conditions as an excuse when the contract already covers those scenarios.
Read your contract carefully for what 'removal' or 'disposal' actually means—if it says 'all materials,' you can't later claim solids were unexpected and demand more money
Don't assume pumpability or easy removal methods are guaranteed—if the contract doesn't promise easy access or specific removal methods, you're responsible for figuring it out
Document site conditions before signing and negotiate specific exclusions upfront; once you sign a contract requiring 'all' materials removed, courts will hold you to it