Information Last Revised: 3/30/93
TTP Reference Number: 321105
1. Technical Name of Technology: Unsaturated Flow Apparatus (UFA) Centrifuge
2. Common Name of Technology: UFA Centrifuge
3. PI and Telephone No: J.L. Conca, (509) 375-4787; Judith Wright, (509) 372-0569
4. Affiliation: Washington State University and Pacific Northwest Laboratory
5. Technology Category: Characterization and Monitoring Technologies
6. Developers: Washington State University and Pacific Northwest Laboratory
7. Application
7.1. Where (in-situ/ex-situ): ex-situ
7.2. Media: groundwater and substrate
7.3. Targeted Contaminants: VOC's and other contaminants
8. Scope of project (feasibility study, treatability, bench, pilot, field):
Lab support for field studies
9. Integrated Demonstration (ID) Need/Requirements:
There is a need for understanding contaminant distribution and behavior in subsurface environments at the VOC-Arid ID. In addition, there is a need for remote, in-situ, or other onsite methods for increased safety and cost effectiveness for local characterization of contaminants.
The alternative to UFA is to develop a vadose zone parameter/characterization data base and to rely on extrapolations of contaminant behavior from less reliable assumptions (e.g., data based on wetter vadose zone conditions) which could result in a higher risk of not choosing the most appropriate restoration strategy for this region of the subsurface. Inadequate predictive capability in this area will lead to loss of time, money, and credibility in DOE meeting its long-term environmental restoration goals. The major benefit of this technology is improved predictive capabilities of VOC migration, greater probability of choosing successful restoration strategies, improved remediation schedules, and a reduced need in the future for lengthy experimental programs. Cost savings on the basis of time and effort needed for experiments alone is reduced by at least two orders of magnitude as transport data can be obtained by the UFA in hours as opposed to months to years by more conventional methods.
10. Objective
10.1. Objective of technology (e.g., This technology will destroy VOCs in groundwater.):
The unsaturated flow analyzer (UFA) is a laboratory instrument that simulates the migration of VOCs, microbial nutrients, and water in the subsurface environment of arid sites. Instead of taking weeks or years to obtain hydraulic transport data on unsaturated environments, the UFA can achieve steady state in several hours. This system is a more rapid method of obtaining transport data. The UFA can address any flow transport problem involving any fluid in any porous media under almost any condition.
10.2. Baseline (baseline technology to which it is compared):
Traditional column experiments (Columns)
11. Process Description:
Soil samples will be collected from the Hanford site using cable tool drilling/split spoon sampler technology. The soil or bedrock samples are transferred to a specially designed titanium canister and subjected to as much as 20,000 g in a open-flow centrifugation device. A rotating seal assembly fitted to the canister allows an ultra-low flow pump to deliver liquid or gas to the sample surface during centripetal acceleration. When steady state conditions are reached (within a matter of hours), 3 transport parameters will be evaluated 1) hydraulic conductivity to measure permeability, 2) diffusion coefficient, 3) breakthrough retardation.
UFA supports the development of restoration technologies such as vapor extraction (e.g., estimate vapor migration rates) or bioremediation (e.g., estimate nutrient delivery rates) for unsaturated soils. In addition, the UFA technology is a predictive tool, i.e., "time machine", that can be used 1) to validate the predictive models of subsurface contaminant migration and 2) to screen the performance of various remediation technologies in the field.
11.1. Input:
Soil samples and liquid (e.g., carbon tetrachloride) or gas to measure fluid transport.
11.2. Output:
The carbon tetrachloride that is introduced into the UFA will be contained in the collection chamber. It is anticipated that during one year, no more than 1 liter of carbon tetrachloride will be introduced into the chamber. In addition to the carbon tetrachloride, any remaining water, i.e., pore water, that exists within the soil will also be collected in the collection chamber. Transport data and a compilation of data for Hanford sediments will also be one of the final output elements.
12. Summary of Technology Advantages (relative to the baseline: faster, better, cheaper, safer):
The UFA allows acquisition of data within hours or days rather than months to years. The UFA directly measures transport parameters at water contents well below any existing method, down to water contents of a few percent and hyrolic conductivities down to 10 -10 cm/s in a few days. The UFA improves the predictive capabilities of VOC migration and greater probability of choosing successful restoration strategies. This technology can also be used to do quick screening. The UFA also can provide data to describe field conditions, which cannot be easily or quickly obtained under normal conditions.
13. Limitations of Technology (relative to the baseline: faster, better, cheaper, safer):
There is no limitation to the use of this technology, provided that the soil can fit into the sample chamber.
14. Major Technical Challenges:
One of the major challenges is the preparation of the soil sample, i.e., obtaining undisturbed samples. After the sample is taken the soil drys. It can then be easily jostled around and disturbed. The UFA contains some plastic parts that are not chemically compatible with the carbon tetrachloride that is introduced into the system. Some of these parts will need to be remade from material that is compatible with the carbon tetrachloride.
15. Technical Effectiveness:
15.1. Performance
15.1.1. Remaining Contamination: (contamination mobility reduction, volume reduction, toxicity reduction)
Summary (20 words or less): It is anticipated that 1 liter of carbon tetrachloride will need to be disposed each year. Much of this carbon tetrachloride will be in solution in groundwater.
Further Description (unlimited length): Discussions are occurring with PNL Safety to coordinate the pickup of wastes. In this lab, mixed waste samples will not be run. It is likely that PNL will purchase a UFA for hot cell work.
15.1.2. Process Waste
15.1.2.1. Status of waste (mobility, volume, hazard, recyclability)
Summary (20 words or less): Not applicable
Further Description (unlimited length):
15.1.2.2. Treatment (needed, available)
Summary (20 words or less): After shipment offsite, the carbon tetrachloride will be either incinerated or disposed of into an appropriate liquid waste treatment facility.
Further Description (unlimited length):
15.1.2.3. Decontamination / Decommissioning
Summary (20 words or less): Not applicable
Further Description (unlimited length):
15.1.2.4. Disposal (needed, available)
Summary (20 words or less): Not applicable
Further Description (unlimited length):
15.1.3. Practicality
15.1.3.1. Foreclose Future Options
Summary (20 words or less): Not applicable
Further Description (unlimited length):
15.1.3.2. Reliability
Summary (20 words or less): To date, no serious mechanical, corrosion or process problems have occurred.
Further Description (unlimited length):
15.1.3.3. Failure Control
Summary (20 words or less): The device includes the standard safety precautions used for centrifuges.
Further Description (unlimited length):
15.1.3.4. Ease of Use
Summary (20 words or less): Within one day, a worker may be trained to operate the UFA. A PNL technical procedure has been developed to assist in that effort.
Further Description (unlimited length): After a relatively short period of onsite training with an experienced operator, a new worker may operate the technology alone. At this point, the UFA is able to be run by a unsupervised technician who is able to make many different types of decisions. The UFA is a research tool, however, its operation is simple.
15.1.3.5. Infrastructure
Summary (20 words or less): Any precision machine shop is capable of producing the parts that are needed for the UFA.
Further Description (unlimited length):
15.1.3.6. Versatility
Summary (20 words or less): The UFA is capable of handling any porous media and any fluid.
Further Description (unlimited length):
15.1.3.7. System Compatibility
Summary (20 words or less): Not available
Further Description (unlimited length):
15.1.3.8. Off-the-Shelf (procurement ease)
Summary (20 words or less): Able to purchase centrifuge off the shelf.
Further Description (unlimited length):
15.1.3.9. Maintainability
Summary (20 words or less): Not available
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15.1.3.10. Safety Measures
Summary (20 words or less): Not available
Further Description (unlimited length):
15.1.4. "Works" (functions as intended):
Summary (20 words or less): When matched up against traditional column experiments, UFA has matched up 100% of the time against those methods.
Further Description (unlimited length): Initial discussions have also identified modifications that may need to occur for this technology to be used in a radioactive environment.
15.2. Cost
15.2.1. Start-Up Cost
Summary (20 words or less): The present cost of the UFA and support equipment is $100K.
Further Description (unlimited length): A more cost effective UFA can be purchased for $50K. This system can be used only for soil, has no temperature capability, and does not have a strobe light.
15.2.2. Operations and Maintenance Cost
Summary (20 words or less): The average annual operating and maintenance cost is $10K. (This cost includes a $2K maintenance contract.) This includes the cost of the sample holders.
Further Description (unlimited length):
15.2.3. Life-cycle cost
Summary (20 words or less): The centrifuge is guaranteed for 5-10 years.
Further Description (unlimited length):
15.3. Time
15.3.1. Years Until Available
Summary (20 words or less): Able to purchase centrifuge off-the-shelf.
Further Description (unlimited length):
15.3.2. Speed/Rate
Summary (20 words or less): The UFA can achieve results in 3 days.
Further Description (unlimited length): This compares to the months and years that are needed to achieve results with traditional column methods, or the 13 years that are needed for in situ analysis.
15.3.3. Years to Finish
Summary (20 words or less): Not available
Further Description (unlimited length):
16. Environmental Safety and Health
16.1. Worker Safety
16.1.1. Exposure to Hazardous Materials/Hazards
Summary (20 words or less): Proper laboratory procedures will be followed to minimize any worker exposure to carbon tetrachloride.
Further Description (unlimited length): An organic vapor analyzer and organic dosimeter will be used by onsite UFA workers. The UFA is housed in a 2 inch steel containment that is strong enough to withstand any failure from the centrifuge.
16.1.2. Physical Requirements
Summary (20 words or less): Not applicable
Further Description (unlimited length):
16.1.3. Number of People Required
Summary (20 words or less): One technician is required.
Further Description (unlimited length):
16.2. Public Health and Safety
16.2.1. Accidents
Summary (20 words or less): Not applicable
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16.2.2. Routine Releases
Summary (20 words or less): Not applicable
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16.2.3. Transportation
Summary (20 words or less): Not applicable
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16.3. Environmental Impacts
16.3.1. Ecological Impacts
Summary (20 words or less): Not applicable
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16.3.2. Aesthetics
Summary (20 words or less): Not applicable
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16.3.3. Natural Resources
Summary (20 words or less): Not applicable
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16.3.4. Energy Demands
Summary (20 words or less): Power usage is minimal.
Further Description (unlimited length):
17. Socio-Political Interests
17.1. Public Perception
17.1.1. Proponent Reputation
Summary (20 words or less): Not applicable
Further Description (unlimited length):
17.1.2. Familiarity / Understandability
Summary (20 words or less): The public may have some knowledge, but not a fundamental understanding, of this technology.
Further Description (unlimited length): There have been several press releases and local television news clips on UFA. No adverse reactions are anticipated. There may be some question regarding how this technology can accurately simulate the natural environment. The UFA uses pristine soil samples from the Hanford site and imposes exact condition on the soils.
17.2. Tribal Rights / Future Land Use
17.2.1. Capacity for Unrestricted Use (terrestrial, aquatic)
Summary (20 words or less): Not applicable
Further Description (unlimited length):
17.3. Socio-Economic Interests
17.3.1. Economic Impacts
Summary (20 words or less): No significant economic impacts are anticipated.
Further Description (unlimited length):
17.3.2. Labor Force Demands
Summary (20 words or less): No significant labor force demands are anticipated.
Further Description (unlimited length):
18. Regulatory Objectives
18.1. Compatibility with Cleanup Milestones
Summary (20 words or less): Not available
Further Description (unlimited length):
18.2. Regulatory Infrastructure / Track Record
Summary (20 words or less): No approvals are anticipated for this technology. Third party reviews of this technology for the grout program have occurred.
Further Description (unlimited length):
18.3. Regulatory Compliance
Summary (20 words or less): It is not anticipated that any environmental regulations impact UFA.
Further Description (unlimited length): Some discussion with State regulatory officials regarding this technology has occurred over the past 3 years. It is not anticipated that any approvals will be needed to operate this technology.
19. Industrial Partnerships
19.1. Company Names:
Beckman
19.2. Rationale:
Beckman developed the rotating seals based on technology to spin oil out of whole rock shales. Beckman has the intellectual property rights.
19.3. Contract Mechanism:
Contract issues are trivial. A CRADA is being put in place between Beckman and PNL. Beckman will provide a prototype instrument for PNL use. PNL will use the instrument to develop a soil classification system for arid soils.
19.4. Other Potential Companies:
Environmental companies may be very interested in working with PNL to test the performance of their technologies on arid soils. There may be a need to work with principal investigators who are assessing the feasibility of laboratory user facilities for site remediation. The USGS has made plans to purchase a UFA. The technology may have application to hot cell testing, but further development is needed to design radiation-hardened equipment. In order to explore this option, this task would also need to interface with the Robotics Integrated Program and/or the robotics task for the UST-ID as well as PI's assessing development needs for in-hot cell characterization technologies. The concrete industry has expressed an interest in UFA to test reactivity of concrete aggregate to alkaline solutions.
19.5. International: The Japanese are very interested in the UFA. Dr. Conca is working with them to study the movement of pore water through bentonite barriers for their waste repository programs.
20. Intellectual Property
20.1. Patent Ownership:
20.2. Other Owners:
20.3. Patent Number:
21. Cost Sharing:
22. Background on this technology (Where did the idea come from? Who else is doing similar work? What have the results been to date? What is the most significant competitor to this technology?):
Jim Conca initially thought of the UFA concept. Judith Wright later assisted to further develop the technology.
John Nimmo at USGS in Menlo Park, CA, is conducting similar work, however, his system does not have a "flow into" and can only work with soils.
Direct investigation of transport in unsaturated porous media has been technically challenging because reaching hydraulic steady state at low water contents using traditional column methods can take an extraordinary amount of time, resulting in very few experimental data. To overcome some of these difficulties, the UFA was developed and has been deployed over the past two years in support of a number of PNL programs. The method has gained wide acceptance within the scientific community, the DOE national laboratory system and the U.S. Geological Survey. In 1987, a need was identified to develop centrifuge technology in order to estimate soil diffusion coefficient information. One of the challenges was to develop a system with a low flow rate (1 ml/hr). Dr. Conca experimented with medical IV pumps to achieve a low flow rate.
There is no significant competitor to date.
23. Reference Documents:
Conca, J.L., and Wright, J.V. (1992) "Direct Determinations of Unsaturated Flow and Transport", Proceedings of the 12th Annual Hydrology Days Conference, Fort Collins, CO, p.103-116.
Conca, J.L., and Wright, J.V. (1992) "Flow and Diffusion of Unsaturated Gravel, Soils and Whole Rock", Applied Hydrogeology, International Association of Hydrogeologists, vol. 1, p.5-24.
Conca, J.L., and Wright, J.V. (1992) "A New Technology for Direct Measurements and Unsaturated Transport", Proceedings of the Nuclear and Hazardous Waste Management Spectrum '92 Meeting, American Nuclear Society, Boise, ID, Vol. 2, pg. 1546-1555.