Drain cooking liquid. Return beans to the pot, and add 4 cups water and 2 cups broth to just cover the beans. Add onion, garlic, rosemary sprigs, oil, pepper and remaining 1 teaspoon salt. Bring to a boil, cover and reduce heat to low. Simmer for 60 minutes, stirring occasionally. Remove lid, and cook another 60 minutes. Check liquid levels, and add more as needed.