Soaking beans: place all beans (except green split peas) and 10 cups water in a large soup pot. Bring to a boil, let boil for 2-4 minutes more. Remove heat, let stand 2-4 hours. Drain beans and rinse. Set aside.
In a large soup pot, heat the oil over medium heat, and add the onions. Saute for 5 minutes until translucent, then add carrots and celery. Add salt as desired. Saute an additional 5-8 minutes until carrots have softened and celery is translucent. Add beans (except split peas), ham hock and 12 cups water, bring to a boil then simmer at low heat for 45-60 minutes. Add additional salt as desired, pepper, oregano and rosemary. Once beans have softened, add split peas, and simmer an additional 20-25 minutes, until split peas are tender.
Remove ham hock, take meat off bone and chop, return meat to soup and discard bone. If soup becomes too thick, add water and increase spices as desired.
Add spinach, stir for 1-2 minutes in soup till wilted, serve with crusty bread.