Place ham bone and water in a Crock Pot.
Cook on high until broth begins to simmer, then reduce heat to low and
continue to cook, 6 to 8 hours.
Turn off Crock Pot and allow broth to cool overnight. Remove and strain broth from Crock Pot in large bowl; set aside.
Remove ham bone from broth; remove ham from the bone and return ham to broth; discard bones.
The following day, in the same Crock Pot, saute' onion, celery, potatoes and carrots in butter and olive oil until transparent and tender, about 45 minutes.
Add prepared broth and bring to a boil; salt to taste. Once contents are boiling, add barley, cover and reduce heat to low.
Let soup simmer until time to serve, around 1 hour. 1/2 hour before serving, add peas and additional ham.
Note: The ham retains its flavor when added to the broth just before serving.