Technology
Environmental Management
Interim Barrier
An interim barrier, designed to prevent rain and snow melt from percolating into the soil and driving contaminants closer to groundwater has been installed over tanks in T Farm. The barrier is made up of multiple layers of soil, geotextile fabric and a polyurea liner. The barrier is a temporary structure constructed under terms of the Tri-Party Agreement and is one of several interim measures taken to improve protection of the groundwater from previous tank leaks. It will remain in place until a final closure decision is made for the entire farm. The barrier is located over tank T-106, one of Hanford’s oldest single-shell waste storage tanks. T-106 is known for leaking 115,000 gallons of radioactive and chemical waste into the surrounding soil. The barrier covers all or part of nine different tanks.
A second barrier has been designed for installation over the six tanks in the nearby TY Tank Farm. Unlike the barrier at T Farm, the new barrier will use a modified asphalt layer and instead of runoff going to a soil infiltration site it will go to a lined retention basis that will be filled with soil and planted with short-rooted native vegetation that will take up the moisture.
Laser Ablation
A prototype of a key Waste Treatment Plant component, using laser ablation technology, is being tested in the 222-S Laboratory where operating procedures for its use will be developed. The system uses a high-power laser to vaporize a small bit of solid waste to form an aerosol. The aerosol is transferred into plasma where the emitted light is analyzed in a spectrograph. The chemical composition of the waste is determined by analyzing the wavelengths of light emitted by the plasma. Laser ablation will be a primary analytical tool in the plant’s analytical laboratory. It will be used to analyze the solid waste that is fed to the High Level Waste Vitrification Facility as well as the waste glass to ensure they meet all regulatory requirements. The process will allow the plant to prepare samples, analyze their chemical composition and get the results back to the operations staff within one shift.
Surface Geophysical Exploration
Surface Geophysical Exploration (SGE) is helping to improve our understanding of the nature and extent of soil contamination beneath Hanford’s underground waste storage tanks. Our goal is to understand the contamination so action can be taken to protect public health and the environment. SGE requires no excavation. Instead, it uses steel probes inserted into the soil in a grid pattern over a suspected contaminant plume. The probes are connected to a central data collection system which passes electrical currents between them. A plume can be identified and its boundaries mapped because soil impacted by waste conducts electrical current differently than dry or uncontaminated soil.
Off-Riser Sampler System
The Off-Riser Sampler improves our ability to obtain residual waste samples from our underground storage tanks following completion of waste retrieval activities. Historically, sample collection was restricted to waste materials that could be accessed directly beneath a tank riser. Material not near a riser was out of reach. With the new Off-Riser Sampler, operators can reach in and around obstacles to collect residual waste material anywhere in a tank. The remotely-operated device is being further enhanced with an on-board camera so operators will not have to rely on separate in-tank cameras to locate the waste and control the device.
Direct Push Technology
Direct Push is a significant advancement over conventional cone penetrometer equipment to obtain data and soil samples of contaminant plumes around and beneath underground storage tanks and other structures. Penetrometers, which have been used for years to perform shallow soil investigations, rely on the 30-45 ton weight of trucks that force a hollow rod vertically into the soil. Direct Push, on the other hand, uses a hydraulic hammer mounted on a small backhoe unit to drive a rod into the soil either vertically or at an angle. Monitoring instruments can then be lowered into the rod to obtain data on soil contaminants. The rod can also be equipped with a special device to bring soil samples to the surface for more detailed analysis. Direct push minimizes worker contact with contaminants. It also has the advantage of being able to obtain samples beneath structures, significantly improving our ability to obtain data in areas that would otherwise be inaccessible.
