Rinse the split peas, place in a saucepan with the bacon and ham then cover with water. Bring to a boil and simmer approximately 10 minutes, skimming the foam. Drain and return to the saucepan. Cover with 3 litres water and simmer gently 2-3 hours.
Remove the meat from the saucepan and finely dice, discarding the bone and the rind from the bacon. Add diced meat back to the saucepan.
Add the celeraic, carrot, onions and leeks and simmer until vegetables are soft. Add the sausage and simmer 15 minutes, then remove, dice and return to the saucepan. If soup is too thick, add a little water.
Stir in the chopped celery leaves. Season with salt and pepper. Serve.