Dr. Saul Paul Dr. Paul designed and developed TWIST based on US EPA's requirements and input from state and local wastewater officials. He is an environmental engineer with expertise in water resources, watershed modeling, and geographic information systems (GIS) with overall 5 years of experience in the water resources field. He has developed many watershed modeling tools for EPA and various state and local agencies. Dr. Paul is currently leading the development of a web-based onsite sewage tracking system for a county in West Virginia .