Spills
Twin membrane bioreactors help treat low-level radioactive water in Port Granby By Pat Logan
T
he Port Granby Project is part of the larger Port Hope Area Initiative for the development and implementation of a longterm management solution for historical low-level radioactive waste in the municipalities of Port Hope and Clarington, Ontario. Waste from the former Eldorado operation in Port Hope is currently located on a lakeshore site at the south eastern boundary of the Municipality of Clarington at the Port Granby site. The facility has been closed since 1988 and is maintained under a license from the Canadian Nuclear Safety Commission. The Port Granby Project involves relocating approximately 450,000 m3 of historical low-level radioactive waste and marginally contaminated soils, from a waste management facility on the shoreline of Lake Ontario to a new, engineered aboveground mound a kilometre north, for safe long-term management. Other important project components included the construction of a wastewater treatment plant that was required to meet or exceed stringent Canadian Nuclear Laboratories’ requirements for effluent discharge into Lake Ontario. The project has been undertaken by the Port Hope Area Initiative Management Office which includes Atomic Energy of Canada Limited (lead agency/license holder), Public Works and Government Services Canada (major contracts) and Natural Resources Canada (sponsor/founder). Monitoring systems will be installed within the mound and around the perimeter of the longterm waste management facility site. Low-level radioactive waste and contaminated soils will be excavated from the existing site and transported to the new facility. Maple Reinders Construction Ltd. constructed a new wastewater treatment plant (WWTP), to replace the existing one located at the current Port Granby Waste Management Facility on the shoreline of Lake Ontario. The WWTP was the second part of a
62 | May/June 2015
Each tank contains an anoxic zone one, an anoxic zone two and an aerated zone.
three phase contract. Contract A included road upgrades and was completed in 2012. Contract B for the construction of the wastewater treatment plant was awarded in January 2013 and took approximately two years to complete. Contract C will include the construction of a new engineered aboveground mound and relocation of the radioactive waste. In addition to typical construction challenges, the plant had to be operational before excavation of the radioactive waste and its placement in the aboveground mound. Additionally, all construction activities were continuously monitored to identify and take necessary actions to reduce effects on people, the environment and the community’s way of life. Ensuring worker and public safety was the project’s highest priority. AECOM Canada Ltd. was retained by Public Works and Government Services Canada to complete detailed design of the long-term waste management facility, design the associated supporting infrastructure, plan the remediation of the existing waste management
facility and oversee construction. The new plant was designed to treat ground and surface water during placement of the radioactive waste in the new engineered aboveground mound facility. It will also treat contaminated leachate from within the mound once it is closed. Ground and surface water will also be pumped to the new plant from the existing Port Granby Waste Management Facility during excavation. Interception, collection and treatment of contaminated groundwater at the existing site will continue for many years after the project is complete. The principal water treatment processes include equalization, membrane bioreactor (MBR) technology, reverse osmosis and residuals treatment. As Port Hope is located close to Lake Ontario, it was very important to select the right technological solutions in order to guarantee the highest performance, while having the least environmental impact. Equipment requirements included: • Two bioreactor tanks and domes, supplied by Greatario Engineered
Environmental Science & Engineering Magazine