Maxey Flats Radioactive Waste Landfill
Client: State of Kentucky
As the principal engineering subcontractor to URS in the closure of the Maxey Flats Radioactive Waste Landfill for the State of Kentucky, CTI serves as a key partner on the remedial design engineering team, providing CERCLA remedial design and oversight of remedial actions for the closure of 200+ sumps and the installation of the 60+ acre final multi-layer closure cap. CTI is responsible for regulatory compliance, regulatory negotiations, design of Final Closure Cap, project quality and S&H management, engineering, permitting, data analysis, work plan development, construction management, construction, onsite QA, and reporting. CTI coordinated closely with the client (KYDEP) and EPA personnel during the design process when work scheduling and sequencing was affected by stakeholder needs and operational schedule constraints to ensure successful execution of work with minimal impact to the schedule. The project showcases CTI’s ability to integrate environmental, engineering and construction QA services, and to manage radioactive waste-related issues associated with contaminated soils and other waste streams.
The entire site covers approximately 250 acres, and is a LLRW landfill, covered under CERCLA. Landfill and geosynthetics engineering support during design and construction, as well as extensive construction quality assurance are some of the key highlights of this work.
CTI provided full-time construction quality assurance (CQA) and documented the final abandonment, below the Initial Remedial Phase (IRP) liner, of the following structures located within the footprint of the Restricted Area (RA): Monitoring Well UF-10a, eighty-three existing above grade sumps, six below grade dormant sumps, two North Channel headwall sump risers, LSF Tank 1, and six previously grouted above grade LSF tank risers. Also included were improvements to one hundred sixty six of the previously abandoned sumps, size reduction and onsite disposal of all parts, apparatuses and debris, and radiation contamination control throughout the duration of the Project.
Regulatory documents resulting from the remedial design work plan, 30/60/90% progress contract documents, sump abandonment plans, and design basis documentation were all implemented to keep the client up to date with work progress during the course of the engineering design. Slope stability, stormwater infiltration, drainage design, seismic stability modeling, and settlement modeling were used to determine the best approach to capping this legacy radioactive waste site.
The final closure cap used an innovative design consisting of levelling fill, two layers of reinforcing geogrid, a geosynthetic clay liner (GCL), a geomembrane, a geocomposite drainage layer, protective cover soil, and vegetative soil cover. Due to concerns about collapsing waste containers causing subsidence of the cap system, CTI thoroughly investigation and implemented a geogrid reinforcement system to control differential settlements and ensure continuity of the cap drainage system. Stormwater controls and water quality detention basins were also designed into the system. Aerial Lidar surveys helped develop an accurate site topographic map.
To date, the remedial design has been completed and approved by EPA Region 4, construction costs estimates and construction procurement documents completed, all sump abandonment and closure activities completed, and State of Kentucky has competed and procured a construction contractor. Construction is 50% complete on the final cover. CTI is supporting the final construction, performs geotechnical soils analyses, conducts on-site construction quality assurance and associated daily reporting, participates in construction management meetings and oversight, and serves as the State of Kentucky’s on-site expert during the construction phase.
- Integration of environmental, engineering and construction services
- Management of radioactive waste- related issues associated with contaminated soils and other waste streams
- Regulatory Compliance and Negotiations
- Design of Final Closure Cap
- Project Quality and S&H management
- Engineering, Permitting, and Data Analysis
- Work Plan Development
- Construction Management
- Construction Performance and Onsite QA
- Data Reporting