Tim Ashworth

Geosyntec's practitioners work with regulators and stakeholders to develop solutions for a range of radiological challenges, including waste management and disposal, waste packaging and transportation, facility decontamination and decommissioning (D&D), and environmental restoration for government and private clients. Our established credibility with regulators contributes to securing the approvals needed to move demanding projects forward in a timely manner. Engineering and designing containment facilities for the safe, long-term disposal of radiological and mixed (radiological and hazardous) wastes challenges the norms in terms of technology demonstration, design life, and material performance. The extremely long half-lives of many radionuclides present in these wastes mean that the radiological characteristics of these materials will be persistent over long periods of time. This requires that they be disposed and managed in a controlled manner as a disposal facility ages. The levels of radioactivity within the waste disposed of in a facility also need to be considered during the long-term evaluations, or performance assessments. Geosyntec has conducted performance assessments under several different regulatory settings to demonstrate that the disposal facilities are protective of human health and the environment, assessing both internal risks as the waste decays within the disposal facility and external to disposal facilities as the performance of the landfill construction materials age and are modeled at very long times (e.g., hundreds to thousands of years) to eventually transmit leachate and contaminants to the underlying geology. The results of the performance assessments are crucial towards our clients understanding of their design choices and future liabilities. When the U.S. Department of Energy (DOE) decided to decommission its nuclear weapons complex facilities at Fernald, Ohio, they relied on our expertise to design and provide construction quality assurance services for the low-level radioactive waste disposal facilities built to contain impacted soils and demolition debris. Geosyntec met aggressive DOE schedule requirements and delivered award-winning, state-of-the-art facilities with a design life of at least 200 years using currently available technology. In doing so, we helped DOE and its contractor teams complete site closure years ahead of their original schedules, and billions below the original estimate. When DOE decided to decommission its nuclear weapons complex facility at Portsmouth, Ohio, Geosyntec was again tapped to provide design and permitting for the on-site waste disposal facility. Geosyntec has also successfully assisted clients in the related practice area of management and containment of by-products and wastes that contain naturally occurring radioactive materials (NORM) associated with ore processing residuals. For example, a multinational company owned a processing facility with NORM and Technologically Enhanced Naturally Occurring Radioactive Material (TENORM) containing uranium and thorium impacts to buildings, equipment, and process area soils. Geosyntec assessed and characterized site conditions, then designed a secure, on-site disposal facility, dismantled ore processing equipment, and impacted soils. Our design addressed the liner and cover containment systems; sequencing for constructing, filling, and closing the facility; facility operation and maintenance; and post-closure environmental monitoring. The requirement to consider a performance over a period of more than 10,000 years led to significant challenges in design and modeling of the disposal facility. As the general contractor for the project, we implemented a stringent construction and radiological safety program. This included establishing and operating an on-site radiological laboratory capable of measuring gross alpha/beta activity and gamma spectroscopy on debris, impacted soils, airborne particulates, and water. When complete, over 11,000 loads of excavated soils and plant debris (or 75,000 cubic meters) were transported and disposed of in the facility and more than 87,000 drums were retrieved, processed, transported and disposed. The project was completed with more than 1 million man-hours without either a lost-time accident or a radiological incident, a testament to the importance of safety and the safety culture that Geosyntec has established.