Place beans in a large bowl; add cool water to cover. Soak 5 hours or overnight. Drain beans, discarding water; rinse with cool water., In a 6-qt. slow cooker, layer beans, onions, carrots, celery and pork. Add seasonings, broth and ale. Cook, covered, on low 6-8 hours or until beans and pork are tender. , Remove pork; shred with 2 forks. Stir in tomatoes, spinach and salt. Return pork to slow cooker. Cook, covered, on low for 15-20 minutes or until heated through.