5 Matching Results

Search Results

Advanced search parameters have been applied.

Barometric pumping with a twist: VOC containment and remediation without boreholes

Description: Objectives of Phase I (completed Nov. 1995) was to evaluate the feasibility of applying surface sealing and venting features to contain and remediate volatile organic compound (VOC) contaminated soils in the vadose zone. In Phase II, the remediation system will be installed at the Radioactive Waste Management Complex of INEL. It will cover an area of the landfill known to be contaminated with chlorinated hydrocarbons, deposited in shallow trenches. Operation will be monitored for 12 to 18 months to evaluate the impact on soil gas displacement. The 4 key components are the surface seal, plenum, vent assembly, and soil vapor monitoring points.
Date: December 31, 1996
Creator: Lowry, W.; Dunn, S.D. & Neeper, D.
Partner: UNT Libraries Government Documents Department

Barometric pumping with a twist: VOC containment and remediation without boreholes

Description: A large national cost is incurred in remediating near-surface contamination such as surface spills, leaking buried pipelines, and underground storage tank sites. Many of these sites can be contained and remediated using enhanced natural venting, capitalizing on barometric pumping. Barometric pumping is the cyclic movement experienced by soil gas due to oscillations in atmospheric pressure. Daily variations of 5 millibars are typical, while changes of 25 to 50 millibars can occur due to major weather front passage. The fluctuations can cause bulk vertical movement in soil gas ranging from centimeters to meters, depending on the amplitude of the pressure oscillation, soil gas permeability, and depth to an impermeable boundary such as the water table. Since the bulk gas movement is cyclic, under natural conditions no net advective vertical movement occurs over time. Science and Engineering Associates, Inc., is developing an engineered system to capitalize on the oscillatory flow for soil contaminant remediation and containment. By design, the system allows normal upward movement of soil gas but restricts the downward movement during barometric highs. The earth`s surface is modified with a sealant and vent valve such that the soil gas flow is literally {open_quotes}ratcheted{close_quotes} to cause a net upward flow over time. A key feature of the design is that it does not require boreholes, resulting in a very low cost remediation effort and reduced personnel exposure risk. In the current phase (Phase I) the system`s performance is being evaluated. Static and transient analysis results are presented which illustrate the relative magnitude of this advective movement compared to downward contaminant diffusion rates. Calculations also indicate the depth of influence for various surface and soil configurations. The system design will be presented, as well as a cost assessment compared to conventional techniques.
Date: December 31, 1995
Creator: Lowry, W.; Dunn, S.D.; Walsh, R. & Zakian, P.
Partner: UNT Libraries Government Documents Department

SEAMIST{trademark} in-situ instrumentation and vapor sampling system applications in the Sandia Mixed Waste Landfill Integrated Demonstration program: Final report

Description: The Mixed Waste Landfill Integrated Demonstration was tasked with demonstrating innovative technologies for the cleanup of chemical and mixed waste landfills that are representive of sites occurring throughout the DOE complex and the nation. The SEAMIST{trademark} inverting membrane deployment system has been used successfully at the Mixed Waste Landfill Integrated Demonstration (MWLID) for multipoint vapor sampling, pressure measurement, permeability measurement, sensor integration demonstrations, and borehole lining. Several instruments were deployed inside the SEAMIST{trademark}-lined boreholes to detect metals, radionuclides, moisture, and geologic variations. The liner protected the instruments from contamination, maintained support of the uncased borehole wall, and sealed the total borehole from air circulation. Recent activities included the installation of three multipoint vapor sampling systems and sensor integration systems in 100-foot-deep vertical boreholes. A long term pressure monitoring program has recorded barometric pressure effects at depth with relatively high spatial resolution. The SEAMIST{trademark} system has been integrated with a variety of hydrologic and chemical sensors for in-situ measurements, demonstrating its versatility as an instrument deployment system that allows easy emplacement and removal. Standard SEAMIST{trademark} vapor sampling systems were also integrated with state-of-the-art volatile organic compound analysis technologies. The results and status of these demonstration tests are presented.
Date: September 1, 1995
Creator: Williams, C.; Lowry, W.; Cremer, D. & Dunn, S.D.
Partner: UNT Libraries Government Documents Department

YMP Engineered Barrier Systems Scaled Ventilation Testing

Description: Yucca Mountain, approximately 100 miles northwest of Las Vegas, Nevada, has been selected as the site for the nation's first geologic repository for high level nuclear waste. The Yucca Mountain Project (YMP) is currently developing the design for the underground facilities. Ventilation is a key component of the design as a way to maintain the desired thermal conditions in the emplacement drifts prior to closure. As a means of determining the effects of continuous ventilation on heat removal from the emplacement drifts two series of scaled ventilation tests have been performed. Both test series were performed in the DOE/North Las Vegas Atlas facility. The tests provided scaled (nominally 25% of the full scale emplacement drift design) thermal and flow process data that will be used to validate YMP heat and mass transport codes. The Phase I Ventilation Test series evaluated the ability of ambient ventilation air to remove energy under varying flow and input power conditions. The Phase II Ventilation Test series evaluated the ability of pre-conditioned ventilation air to remove energy under varying flow, input temperature and moisture content, and simulated waste package input power conditions. Twenty-two distinct ventilation tests were run.
Date: November 22, 2002
Creator: Dunn, S.D.; Lowry, B.; Walsh, B.; Mar, J.D.; Howard, C.; Johnston, R. et al.
Partner: UNT Libraries Government Documents Department

Development of the SEAtrace{trademark} barrier verification and validation technology. Final report

Description: In-situ barrier emplacement techniques and materials for the containment of high-risk contaminants in soils are currently being developed by the Department of Energy (DOE). Because of their relatively high cost, the barriers are intended to be used in cases where the risk is too great to remove the contaminants, the contaminants are too difficult to remove with current technologies, or the potential movement of the contaminants to the water table is so high that immediate action needs to be taken to reduce health risks. Assessing the integrity of the barrier once it is emplaced, and during its anticipated life, is a very difficult but necessary requirement. Science and Engineering Associates, Inc., (SEA) and Sandia National Laboratories (SNL) have developed a quantitative subsurface barrier assessment system using gaseous tracers in support of the Subsurface Contaminants Focus Area barrier technology program. Called SEAtrace{trademark}, this system integrates an autonomous, multi-point soil vapor sampling and analysis system with a global optimization modeling methodology to locate and size barrier breaches in real time. The methodology for the global optimization code was completed and a prototype code written using simplifying assumptions. Preliminary modeling work to validate the code assumptions were performed using the T2VOC numerical code. A multi-point field sampling system was built to take soil gas samples and analyze for tracer gas concentration. The tracer concentration histories were used in the global optimization code to locate and size barrier breaches. SEAtrace{trademark} was consistently able to detect and locate leaks, even under very adverse conditions. The system was able to locate the leak to within 0.75 m of the actual value, and was able to determine the size of the leak to within 0.15 m.
Date: August 1, 1998
Creator: Dunn, S.D.; Lowry, W.; Walsh, R.; Rao, D.V. & Williams, C.
Partner: UNT Libraries Government Documents Department