If its small enough to boil then i would do as follows:
Scrub all loose debris off
Fill the pot, boil for 20 minutes
Empty pot
Fill the pot, boil for 15 minutes
Empty pot
Fill the pot, boil for 10 minutes
Empty pot
Fill the pot, boil for 5 minutes
Empty pot. Get a bucket with a top and put the wood in the bucket, fill it full of hot hot water and let it soak over night. It will still turn water but running a couple carbon cycles in the tank and weekly water changes and youll be fine in no time.
If you cant boil them then i would scrub/pressure wash the pieces and soak them in a large vessel for atleast one week pref. three.