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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Detailed Characterization of Vitrinite-Rich Subbituminous and Bituminous Coals for Utilization in Carbon Fiber Precursor Production

Chemical structures of candidate coals (one subbituminous coal from the Powder River Basin and three bituminous Eastern US coals) were examined for potential low-cost carbon fiber precursor production. Here, the structural evaluation examined the carbon skeleton ( 13 C nuclear magnetic resonance (NMR) and high-resolution transmission electron microscopy (HRTEM)), the heteroatom functionality (X-ray photoelectron spectroscopy (XPS) Fourier transform infrared spectroscopy (FTIR) and NMR), the structural ordering and distribution of PAH sizes (HRTEM), and an estimation of the molecular weight distribution (laser desorption ionization mass spectrometry, LDIMS). The molecular compositional distributions were also evaluated for a mixed solvent extract (atmospheric pressure photoionization, 21 T Fourier transform ion cyclotron resonance mass spectrometry, FT-ICR MS). Significant structural differences existed between the subbituminous and bituminous coals, as expected with coalification (with the bituminous coals having a higher carbon content, lower oxygen content, higher aromaticity values, larger cluster sizes, and so forth). While the bituminous coals were similar in structure (close in rank with Blue Gem being hvAb and the rest being hvBb), structural differences were still evident. Specifically, structural similarities were evident for the average properties of Herrin and Springfield coals: same rank, similar moisture, and volatile matter yields, along with similar aromaticity and carbon and hydrogen content. However, significant structural differences were observed at the molecular level by 21 T FT-ICR MS, which showed that the Springfield coal was structurally more complex. Specifically, 21740, 16931, 30190, and 12982 unique elemental compositions were identified for the Monarch, Herrin, Springfield, and Blue Gem coals, further illustrating the complexity of the coal.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

Non-invasive toluene sensor for early diagnosis of lung cancer

Here we present, quantification of volatile organic compounds in human breath for early detection of lung cancer to increase survival probability. Graphene oxide nanosheets synthesized by modified Hummer’s method were employed as a sensing element to detect the presence of toluene in the sample. Optical and morphological characterization of synthesized nanomaterial was performed by UV-Visible spectroscopy and scanning electron microscopy (SEM) respectively. Spectroscopic assay shows a linearly decreasing intensity of GO absorption peak with increasing toluene concentration with a linear range from 0-200 pM. While impedimetric sensor developed on a graphene oxide nanosheetsmodified screen printed electrodes displayed a decreasing electron transfer resistance increasing toluene with much larger linear range of 0-1000 pM. Reported techniques are advantageous as these are simple, sensitive and cost effective, which can easily be extended for primary screening of other VOCs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Evaluation of Thermal Evolution Profiles and Estimation of Kinetic Parameters for Pyrolysis of Coal/Corn Stover Blends Using Thermogravimetric Analysis

The thermal evolution profiles and kinetic parameters for the pyrolysis of two Montana coals (DECS-38 subbituminous coal and DECS-25 lignite coal), one biomass sample (corn stover), and their blends (10%, 20%, and 30% by weight of corn stover) have been investigated at a heating rate of 5°C/min in an inert nitrogen atmosphere, using thermogravimetric analysis. The thermal evolution profiles of subbituminous coal and lignite coal display only one major peak over a wide temperature distribution, ~152–814°C and ~175–818°C, respectively, whereas the thermal decomposition profile for corn stover falls in a much narrower band than that of the coals, ~226–608°C. The nonlinearity in the evolution of volatile matter with increasing percentage of corn stover in the blends verifies the possibility of synergistic behavior in the blends with subbituminous coal where deviations from the predicted yield ranging between 2% and 7% were observed whereas very little deviations (1%–3%) from predicted yield were observed in blends with lignite indicating no significant interactions with corn stover. In addition, a single first-order reaction model using the Coats-Redfern approximation was utilized to predict the kinetic parameters of the pyrolysis reaction. The kinetic analysis indicated that each thermal evolution profile may be represented as a single first-order reaction. Three temperature regimes were identified for each of the coals while corn stover and the blends were analyzed using two and four temperature regimes, respectively.

Bhagavatula, Abhijit↗
DOE OSTI2013

Kinetic Study of Coal and Biomass Co-Pyrolysis Using Thermogravimetry

The objectives of this study are to investigate thermal behavior of coal and biomass blends in inert gas environment at low heating rates and to develop a simplified kinetic model using model fitting techniques based on TGA experimental data. Differences in thermal behavior and reactivity in co-pyrolysis of Powder River Basin (PRB) sub-bituminous coal and pelletized southern yellow pine wood sawdust blends at low heating rates are observed. Coal/wood blends have higher reactivity compared to coal alone in the lower temperature due to the high volatile matter content of wood. As heating rates increase, weight loss rates increase. The experiment data obtained from TGA has a better fit with proposed two step first order reactions model compared single first order reaction model.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2017

Advanced Fossil Energy Separations and Analysis Research – Thermal Desorption Using Spouted Beds

Mercury and other contaminants in emissions from coal-fired power plants are of interest due to the cost associated with capture and disposal of toxic mercury species. It had recently been postulated in the fossil energy community that spouted beds may be a viable coal pre-treatment technique for thermal desorption of mercury. Spouted beds have the potential to be a near-ideal solid-gas contactor for desorption of mercury species, especially with a few proposed design changes specific for this application. Introduction of draft tubes for spouted beds has addressed some issues with scale-up to better handle the throughput and particle size found in coal-fired power plants. In Phase I, Mainstream Engineering invented and developed a Venturi draft tube spouted bed (VDTSB) to enable process scale-up with fine coal particles and to improve heat and mass transfer. The VDTSB concept increases suction at the bottom of the bed to better entrain material (and reduce the propensity for bridging) at the bottom of the conical vessel. The main advantages of this patent-pending approach are the ability to accept a wide range of coal particle sizes, good heat/mass transfer, process scalability, and robustness. The desorber design was optimized through bed flow visualization experiments; these experiments demonstrated the increased throughput and ease of process scale-up. A high-temperature pilot-scale VDTSB desorber system was designed, fabricated, commissioned, and tested. The heat and mass transfer rates with the VDTSB were measured and compared to a baseline spouted bed with and without a conventional straight draft tube. Pilot-scale VDTSB system performance tests were completed with the Energy and Environmental Research Center (EERC) to measure the rate of mercury desorption over a range of pulverized coal particle sizes, bed temperatures, and reactor geometry. Based on performance results, an initial technoeconomic analysis (TEA) was completed to estimate the cost reduction for emissions treatment compared to current flue-gas mercury capture systems. The following was accomplished in Phase I: Developed scalable design correlations for high-throughput spouted bed systems; Determined cycle time distribution (CTD) and turnover time for straight and Venturi draft tube spouted beds, and showed the VDTSB had lower cycle time (faster turnover) than the straight draft tube (SDT); Reduced weighted-average turnover time by 14% to 43% with Venturi draft tube; narrowed the CTD by up to 75%; Measured heat and mass transfer within the pilot-scale VDTSB desorber and showed that the highest heat transfer rate was 2.98 kW/m 2 ·s with 400 µm particles at a 10 L/min motive gas flowrate; Measured mercury (Hg) desorption rate for lignite, bituminous, and subbituminous coal at 200 °C, 225 °C, 250 °C and 275 °C; Achieved 5.6×10 -10 kg/m 2 -h, 2.6×10 -10 kg/m 2 -h, and 6.5×10 -11 kg/m 2 -h Hg removal rates for lignite, bituminous, and sub-bituminous coals, respectively with no loss in volatile matter and an increase in heating value due to a reduction in moisture content; The unoptimized VDTSB pilot desorber decreased the total mercury concentration of lignite and bituminous coal tests by 61% (dry basis). The subbituminous Powder River Basin (PRB) coal showed a reduction of 18%; Based on our TEA of coal-fired power plants, implementing the VDTSB for coal pretreatment could reduce the mercury capture capital and operating expenses by 36% and 38%, respectively, which exceeded the target goal of 25% reduction; A patent application was prepared, and the results were presented at the 2017 AIChE Annual Meeting (Minneapolis, MN).

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

Calculating the Effects of Solids Input and Removal as a Temperature Control in the Advanced Scale Up Reactor Experiment (ASURE) Facility at NETL Using Aspen

The Advanced Scale Up Reactor Experiment (ASURE) facility at NETL is being designed to be a fuel-flexible multi-purpose reactor that can be used for pyrolysis/gasification or evaluation of other high pressure “circulating fluidized bed” (CFB) chemical processes. The initial system design calculations for pyrolysis/gasification are presented in this work showing the expected performance of the ASURE facility when used as a biomass conversion reactor. Several other areas of application include gasification of any carbonaceous fuel including biomass, coal, plastics, and other waste materials. The reactor can therefore be used to produce SYNGAS of various compositions and hydrogen as well as other high value chemicals resulting from a typical tuned gasification process. This paper discusses an ASPEN model of the facility, focusing on the riser of the CFB reactor and the solids recirculation loop. The ASPEN model divides the riser into two sections. A bottom section which receives ash, char and sand which have been recirculated from a return loop. In this section an inert fluidization gas, (N2 or CO2), is introduced which acts as the primary mover of the solids through the system. The bottom section is equipped with a restricted air feed so that the recirculated char can be partially oxidized. This oxidation process along with the inventory of recirculating sand are used to effectively control the temperature in the following two chemical conversion sections of the reactor which are the pyrolysis zone followed by a tar cracking zone. Fresh fuel is added to the pyrolysis zone and undergoes drying and devolatilization. The products ash, char, volatile matter, and water vapor exit the pyrolysis zone and enter the reaction block for tar cracking. Steam and CO2 gasification reactions will be incorporated into the tar cracking zone, however at the design operating temperature, conversion from these reactions is expected to be essentially zero. The unit when completed in 2026 will test mixtures of biomass, plastics, and waste coal. This presentation discusses the basic ASPEN engineering design model for this project and provides preliminary sensitivity studies to determine how the various parts of the reactor will perform.

ASSURE↗
DOE OSTI2019

The potential role of methanesulfonic acid (MSA) in aerosol formation and growth and the associated radiative forcings

Atmospheric marine aerosol particles impact Earth's albedo and climate. These particles can be primary or secondary and come from a variety of sources, including sea salt, dissolved organic matter, volatile organic compounds, and sulfur-containing compounds. Dimethylsulfide (DMS) marine emissions contribute greatly to the global biogenic sulfur budget, and its oxidation products can contribute to aerosol mass, specifically as sulfuric acid and methanesulfonic acid (MSA). Further, sulfuric acid is a known nucleating compound, and MSA may be able to participate in nucleation when bases are available. As DMS emissions, and thus MSA and sulfuric acid from DMS oxidation, may have changed since pre-industrial times and may change in a warming climate, it is important to characterize and constrain the climate impacts of both species. Currently, global models that simulate aerosol size distributions include contributions of sulfate and sulfuric acid from DMS oxidation, but to our knowledge, global models typically neglect the impact of MSA on size distributions. In this study, we use the GEOS-Chem-TOMAS (GC-TOMAS) global aerosol microphysics model to determine the impact on aerosol size distributions and subsequent aerosol radiative effects from including MSA in the size-resolved portion of the model. The effective equilibrium vapor pressure of MSA is currently uncertain, and we use the Extended Aerosol Inorganics Model (E-AIM) to build a parameterization for GC-TOMAS of MSA's effective volatility as a function of temperature, relative humidity, and available gas-phase bases, allowing MSA to condense as an ideally nonvolatile or semivolatile species or too volatile to condense. We also present two limiting cases for MSA's volatility, assuming that MSA is always ideally nonvolatile (irreversible condensation) or that MSA is always ideally semivolatile (quasi-equilibrium condensation but still irreversible condensation). We further present simulations in which MSA participates in binary and ternary nucleation with the same efficacy as sulfuric acid whenever MSA is treated as ideally nonvolatile. When using the volatility parameterization described above (both with and without nucleation), including MSA in the model changes the global annual averages at 900 hPa of submicron aerosol mass by 1.2 %, N3 (number concentration of particles greater than 3 nm in diameter) by -3.9 % (non-nucleating) or 112.5 % (nucleating), N80 by 0.8 % (non-nucleating) or 2.1 % (nucleating), the cloud-albedo aerosol indirect effect (AIE) by -8.6 mW m -2 (non-nucleating) or -26 mW m -2 (nucleating), and the direct radiative effect (DRE) by -15 mW m -2 (non-nucleating) or -14  mW m -2 (nucleating). The sulfate and sulfuric acid from DMS oxidation produces 4–6 times more submicron mass than MSA does, leading to an ~10 times stronger cooling effect in the DRE. But the changes in N80 are comparable between the contributions from MSA and from DMS-derived sulfate/sulfuric acid, leading to comparable changes in the cloud-albedo AIE. Model–measurement comparisons with the Heintzenberg et al. (2000) dataset over the Southern Ocean indicate that the default model has a missing source or sources of ultrafine particles: the cases in which MSA participates in nucleation (thus increasing ultrafine number) most closely match the Heintzenberg distributions, but we cannot conclude nucleation from MSA is the correct reason for improvement. Model–measurement comparisons with particle-phase MSA observed with a customized Aerodyne high-resolution time-of-flight aerosol mass spectrometer (AMS) from the ATom campaign show that cases with the MSA volatility parameterizations (both with and without nucleation) tend to fit the measurements the best (as this is the first use of MSA measurements from ATom, we provide a detailed description of these measurements and their calibration). However, no one model sensitivity case shows the best model–measurement agreement for both Heintzenberg and the ATom campaigns. As there are uncertainties in both MSA's behavior (nucleation and condensation) and the DMS emissions inventory, further studies on both fronts are needed to better constrain MSA's past, current, and future impacts upon the global aerosol size distribution and radiative forcing.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1978

Differential scanning calorimetry of coal

Differential scanning calorimetry studies performed during the first year of this project demonstrated the occurrence of exothermic reactions associated with the production of volatile matter in or near the plastic region. The temperature and magnitude of the exothermic peak were observed to be strongly affected by the heating rate, sample mass and, to a lesser extent, by sample particle size. Thermal properties also were found to be influenced by oxidation of the coal sample due to weathering effects.

Gold, P. I.↗
NASA NTRS1978

Development of Methods of Characterizing Coal in Its Plastic State

Coal in its plastic state (typically 400-460 C) was examined by the isothermal Gieseler plastometry of seven selected coals of widely varying plastic properties. Kinetic models were proposed for the isothermal plastometric curves. Plastic behavior was compared with a variety of laboratory analyses and characterizations of these coals, including classical coal analysis; mineral analysis; microstructural analysis (extractable fractions, surface area measurement, and petrographic analysis); and thermal analysis (thermogravimetric analysis, thermomechanical analysis, and differential scanning calorimetry). The phenomenon of a sharp, large, poorly reproducible exotherm in the differential scanning calorimetric analysis of coking coals was examined. Several coal extrudates show mineral distribution, organic maceral composition and overall calorific value to be little affected by 800 F extrusion. Volatile matter and plastic properties are moderately reduced, and the network structure (as gauged by extractables) appears to be slightly degraded in the extrusion process.

Lloyd, W. G.↗
NASA NTRS1986

A study of the possible effect of a thermal post cure on the mechanical properties of the 404 carbon-phenolic ring of the space shuttle solid rocket motor nozzle

Erratic pockets of erosion have occurred on the inner perimeter of the 404 rocket nozzle ring during liftoff firing. It is thought that it may be caused by pockets of volatile matter entrapped during manufacture. A thermal post cure was suggested as a possible means of outgassing such pockets, if they in fact do exist. To confirm an outgassing during a post cure and to establish a working upper temperature limit, thermal gravimetric and differential calorimetric analyses were made on a number of samples from two 404 rings supplied by the manufacturer. Continuous weight loss was observed over the temperature range explored (750 F) indicating outgassing, and a strong exothermic reaction occurs beginning about 390 F. Thus, an upper post cure temperature of 350 F is recommended. To determine the possible effect of a post cure on physical properties, the following tests will be made on matched sets of cured and post cured material: x-radiography (internal structure), linear dimensions, weight, porosity, cross ply thermal expansion, drop and double notch shear strengths, and tensional strength in the ply direction.

Giardini, A. A.↗
NASA NTRS2001

Combustion Stages of a Single Heavy Oil Droplet in Microgravity

Heavy oil is a common fuel for industrial furnaces, boilers, marines and diesel engines. Previous studies showed that the combustion of heavy oil involves not only the complete burning of volatile matters but also the burn-out of coke residues. Detailed knowledge about heavy oil combustion therefore requires an understanding of the different burning stages of heavy oil droplets in the burner. This in turn, demands knowledge about the single droplet evaporation and combustion characteristics. This study measured the temperature and size histories of heavy oil (C glass) droplets burning in microgravity to elucidate the various stages that occur during combustion. The elimination of the gravity-induced gas convection in microgravity allows the droplet combustion to be studied in greater detail. Noting that the compositions of heavy oil are various, we also tested the fuel blends of a diesel light oil (LO) and a heavy oil residue (HOR).

Ikegami, M.↗
DOE OSTI2013

Forest Irrigation of Tritiated Water: A Proven Tritiated Water Management Tool - 13357

Tritium releases from the Old Radioactive Waste Burial Ground (ORWBG) at the SRS in South Carolina has impacted groundwater and surface water. Tritiated groundwater plumes discharge into Fourmile Branch which is a small tributary of the Savannah River, a regional water resource. Taking advantage of the groundwater flow paths and the local topography a water collection and irrigation system was constructed and has been used at the SRS for over a decade to reduce these tritiated water releases to Fourmile Branch. The tritiated water is transferred to the atmosphere by evaporation from the pond surface, and after irrigation, wetted surface evaporation and evapotranspiration through the forest vegetation. Over the last decade SRS has irrigated over 120,000,000 gallons of tritiated water, which diverted over 6000 curies away from Fourmile Branch and the Savannah River. The system has been effective in reducing the flux of tritiated groundwater by approximately 70%. Mass balance studies of tritium in the forest soils before operations and over the last decade indicate that approximately 90% of the tritiated water that is irrigated is transferred to the atmosphere. Dose studies indicate that exposure to site workers and offsite maximally exposed individual is very low, approximately 6 mrem/year and 0.004 mrem/year, respectively. To consistently meet the flux reduction goal of tritium into Fourmile Branch optimization activities are proposed. These efforts will increase irrigation capacity and area. An additional 17 acres are proposed for an expansion of the area to be irrigated and a planting of approximately 40 acres of pine forest plantations is underway to expand irrigation capacity. Co-mingled with the tritiated groundwater are low concentrations of chlorinated volatile organic compounds (cVOCs), and 1,4-dioxane. Research studies and SRS field data indicate the forest irrigation system may have an added benefit of reducing the mass of these co-contaminants via degradation. This semi-passive system makes use of natural processes of hydrology and evapotranspiration to manage tritium-contaminated water by reducing its entrance into site streams and the Savannah River, as well as treating low levels of co-mingled VOCs. SRS expects to operate the system until the tritium decays to levels that represent a minimal impact to Fourmile Branch and the Savannah River, and meets the stakeholder expectations. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2013

Middlesex FUSRAP Site - A Path to Site-Wide Closure - 13416

The road-map to obtaining closure of the Middlesex Sampling Plant FUSRAP site in Middlesex, New Jersey (NJ) has required a multi-faceted approach, following the CERCLA Process. Since 1998, the US ACE, ECC, and other contractors have completed much of the work required for regulatory acceptance of site closure with unrestricted use. To date, three buildings have been decontaminated, demolished, and disposed of. Two interim storage piles have been removed and disposed of, followed by the additional removal and disposal of over 87,000 tons of radiologically and chemically-impacted subsurface soils by the summer of 2008. The US ACE received a determination from the EPA for the soils Operable Unit, (OU)-1, in September 2010 that the remedial excavations were acceptable, and meet the criteria for unrestricted use as required by the 2004 Record of Decision (ROD) for OU-1. Following the completion of OU-1, the project delivery team performed additional field investigation of the final Operable Unit for Middlesex, OU-2, Groundwater. As of December 2012, the project delivery team has completed a Supplemental Remedial Investigation, which will be followed with a streamlined Feasibility Study, Proposed Plan, and ROD. Several years of historical groundwater data was available from previous investigations and the FUSRAP Environmental Surveillance Program. Historical data indicated sporadic detections of Volatile Organic Compounds (VOCs), primarily trichloroethylene (TCE), carbon tetrachloride (CT), and methyl tert-butyl ether (MTBE), with no apparent trend or pattern indicating extent or source of the VOC impact. In 2008, the project delivery team initiated efforts to re-assess the Conceptual Site Model (CSM) for groundwater. The bedrock was re-evaluated as a leaky multi-unit aquifer, and a plan was developed for additional investigations for adequate bedrock characterization and delineation of groundwater contaminated primarily by CT, TCE, and tetrachloroethene (PCE). The investigation was designed to accumulate multiple lines of evidence to determine the source and to delineate the extent of contamination, as required to complete the CERCLA Process and gain regulatory acceptance. Investigative techniques included in-well vertical flow tracing, borehole geophysics and packer testing of temporary test holes to characterize contamination in the bedrock fractures beneath the site, and to delineate likely source areas. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Groundwater Transport of Organic Compounds in Old Salvage Yard, Oak Ridge, TN - 12089

In 1950's and early 1960's during production of nuclear weapons at the US Department of Energy Y-12 National Security Complex in Oak Ridge TN, volatile organic compounds (VOCs) as well as heavy metals, nitrates, and radionuclides were released to the environment. Field investigations revealed that much of this contamination is still present in soil, bedrock, and groundwater. Operational buildings and old disposal facilities at the site have been identified as major sources of contamination. The Old Salvage Yard (OSY) on the western side of the site has long been characterized as the major source of VOC contamination in soil and groundwater. In order to analyze the fate and transport of VOC contamination- including tetrachloroethene (PCE), 1,2- dichloroethene (1,2-DCE), cis-1,2-dichloroethene (cis-1,2-DCE) and vinyl chloride (VC) - in groundwater and soil at the vicinity of OSY, an integrated surface and subsurface flow and transport model has been developed for the Y-12 NSC using the hydrodynamic and transport numerical package, MIKE-SHE. Hydrogeological characteristics of the site such as hydraulic conductivity, and transport parameters such as partitioning coefficients were varied in an effort to delineate subsurface flow and transport pathways, potential downstream impacts on Upper East Fork Poplar Creek, and the potential risk to industrial workers involved in related Decontamination and Decommissioning (D and D) activities. The simulation results were compared with the analytical modeling results previously performed by McLane Environmental Inc. using SESOIL-AT123D. Specific simulations have been performed to investigate the effect of possible remedial action (removing the contaminated surface soil layers) on the fate and transport of VOCs. The results of the MIKE-SHE reported here can be considered as an upper limit for the predicted concentrations. Based on MIKE-SHE results, PCE, 1,2 DCE, cis-1,2-DCE, and VC are sources in soil with potential to equal or exceed industrial groundwater hazard and risk levels at the vicinity of OSY. VOC contaminants in soil and groundwater will decay below industrial groundwater risk and hazard levels within approximately 20 years. Excavation of surface soil layers at the site will considerably reduce the concentration of VOCs in groundwater and the possibility of migration of VOCs to surface waters. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Solar-Powered Air Stripping at the Rocky Flats Site, Colorado - 12361

The U.S. Department of Energy's Rocky Flats Site (the Site), near Denver, Colorado, is a former nuclear weapons facility that was constructed beginning in 1951. With the end of the Cold War, the Site was cleaned up and closed in 2005. Four gravity-driven groundwater treatment systems were installed during cleanup, and their continued operation was incorporated into the final remedy for the Site. All utilities, including electrical power, were removed as part of this closure, so all Site electrical power needs are now met with small solar-powered systems. The Mound Site Plume Treatment System (MSPTS) was installed in 1998 as an innovative system based on zero-valent iron (ZVI). Groundwater flow from the Mound source area containing elevated concentrations of volatile organic compounds (VOCs), primarily in the tetrachloroethene (PCE)-trichloroethene (TCE) family of chlorinated solvents, is intercepted by a collection trench and routed to twin ZVI treatment cells. Later, in 2005, remediation of VOC-contaminated soils at a second up-gradient source area included adding an electron donor to the backfill to help stimulate biodegradation. This reduced concentrations of primary constituents but caused down-gradient groundwater to contain elevated levels of recalcitrant degradation byproducts, particularly cis-1,2-dichloroethene and vinyl chloride. A gravel drain installed as part of the 2005 remediation directs contaminated groundwater from this second source area to the MSPTS for treatment. This additional contaminant load, coupled with correspondingly reduced residence time within the ZVI media due to the increased flow rate, resulted in reduced treatment effectiveness. Elevated concentrations of VOCs were then detected in MSPTS effluent, as well as in surface water at the downstream performance monitoring location for the MSPTS. Subsequent consultations with the Site regulators led to the decision to add a polishing component to reduce residual VOCs in MSPTS effluent. Initially, several alternatives such as commercial air strippers and cascade aerators were evaluated; resulting cost estimates exceeded $100,000. After several simpler alternatives were considered and prototype testing was conducted, the existing effluent metering manhole was converted to house a spray-nozzle based, solar-powered air stripper, at a cost of approximately $20,000. About two-thirds of this cost was for the solar power system, which was initially designed to only provide power for 12 hours per day. Performance data are being collected and adjustments made to optimize the design, determine maintenance requirements, and establish power needs for continuous operation. Analytical data confirm the air stripper is sharply reducing concentrations of residual contaminants. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Vapor Intrusion Mitigation Beneath an Occupied Industrial Building at the Young - Rainey Science, Technology, and Research Center Largo, Florida - 17463

Groundwater contamination, consisting of chlorinated solvents, was identified in the southeastern portion of the Pinellas Site in Largo, Florida. The contamination is beneath Building 100, an 11-acre building that housed manufacturing facilities during US Department of Energy (DOE) operations at the site. Because the building was constructed in phases over a period of decades, it is comprised of approximately 20 different buildings, each with a separate foundation, all of which are now connected under a single roof. Based on the results of a pilot test that indicated the presence of volatile organic compounds beneath the floor slab and, in the absence of state regulations or guidance, DOE elected to proactively address the potential for release of these compounds into the facility by designing and installing a vapor intrusion (VI) mitigation system. To ventilate vapors from beneath the building, piping was installed from beneath the concrete floor slab through the roof, and negative pressure was created using electric blowers. The system design was complicated by foundation walls supporting each of the various sections of Building 100 and by special requirements due to the sensitive nature of the tenant's manufacturing activities and the heightened need for security. This paper addresses significant aspects of the design and construction of a VI mitigation system beneath a large, occupied industrial production facility, including technical, logistical, and environmental challenges; community relations; and regulatory relations. (authors)

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Concluding a steam injection remediation project at a dense non-aqueous phase liquid source zone at the Savannah River site - 15303

Multiple subsurface dense non-aqueous phase liquid (DNAPL) source zones served as the sources for a groundwater plume within the A/M Area of the Savannah River Site. Between 1952 and 1985 over 1,600 metric tons of trichloroethylene, tetrachloroethylene, and 1,1,1-trichloroethane were released to the environment resulting in a 648 hectare plume with the M-Area Settling Basin receiving over half of the solvent discharges. In 1991, DNAPL was found in a water table well and steam injection technology was selected to remediate the source zone. Based on characterization data, the treatment area was 1.21 hectare with depths between 13.7 to 50.3 m. The remediation system included 96 vertical, horizontal, and angled steam injection and soil vapor extraction wells and a thermal monitoring system. Construction of the system began in 2004 and operation began in 2005. Steam was applied to the deep vadose zone first, then progressed to the aquifer, followed by the mid-vadose zone. Multiple steam strategies were utilized to enhance mass removal and were concluded in 2009. Soil vapor extraction continues, with residual temperatures in the deep permeability zones still exceeding 65 deg.C. To date over 204 metric tons of volatile organic compounds (VOCs) have been removed. Post-remediation soil, vapor, temperature, and groundwater data were used to evaluate steam injection effectiveness and demonstrated significant reduction in soil concentration, including removal of DNAPL that was evident in several soil cores prior to treatment. Heating the subsurface increased VOC solubility in groundwater and increased mass removal rates outside the target zone. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗