Patrick J. Clark

Environmental impact of the use of contaminated sediments as partial replacement of the aggregate used in road construction

The Indiana Harbor Canal (IHC) is a waterway extensively polluted with heavy metals and petroleum. Since there are limited disposal options for the petroleum-contaminated sediments (PCSs) of the canal, the environmental impact of IHC dewatered sediment when used as partial replacement of the aggregate used in hot mix asphalt (HMA) for road construction was investigated. In order to assess the long term migration of the target contaminants into the environment, the TCLP, SPLP, and a Constant pH leaching test were applied to a HMA mixture containing 10% of dewatered PCS, a conventional HMA, and the dewatered PCS. None of the heavy metals significantly leached from any of the tested materials in any of the conducted tests. Despite the presence of PAHs in the PCS, these were not found in any of the leachate samples. Finally, among the measured VOCs, only acetone and 2-butanone were found to leach from the asphalt mixtures and the sediment in the Constant pH experiment. It was concluded that it may be environmentally safe to replace the aggregates of the HMA used in road construction in the studied proportions with dewatered PCS based upon leaching levels as compared to TCLP regulated levels. This could be a viable, beneficial use option for the PCS, and therefore, for the canal remediation.

Evaluation of two lead-based paint removal and waste stabilization technology combinations on typical exterior surfaces

A study was conducted to demonstrate the effectiveness of a wet abrasive blasting technology to remove lead-based paint from exterior wood siding and brick substrates as well as to evaluate the effectiveness of two waste stabilization technologies to stabilize the resulting blast media (coal slag and mineral sand) paint debris thereby reducing the leachable lead content. The lead-based paint removal technology effectiveness was determined by the use of an X-ray fluorescence (XRF) spectrum analyzer (L- and K-shell). The effectiveness of the technologies to stabilize the debris was evaluated through the toxicity characteristic leaching procedure (TCLP). Wet abrasive blasting effectively removed the lead-based paint coating from both the wood and brick substrates to below the US Department of Housing and Urban Development Guideline (1mg/cm(2)) with no minimal or no damage to the underlying substrates (P<0.0001). The mean area air levels of lead-containing particulate generated during paint removal were significantly below the personal exposure limit (PEL) (P<0.0001). However, the mean personal breathing zone lead levels were approximately three times higher than the PEL. Neither of the two stabilization technologies consistently stabilized the resultant paint debris to achieve a leachable lead content below the RCRA regulatory threshold of <5 mg/l.

Asbestos Exposures During Routine Floor Tile Maintenance. Part 1: Spray-Buffing and Wet-Stripping

Abstract This study was conducted to evaluate airborne asbestos concentrations during spray-buffing and wet-stripping of asbestos-containing resilient floor tile under three levels of floor condition (poor, medium, and good). Airborne asbestos concentrations were measured by transmission electron microscopy (TEM) before and during each floor care maintenance procedure in the breathing zone of the custodial personnel. Airborne total fiber concentrations were also measured by phase contrast microscopy (PCM) for comparison with the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 0.1 f/cm3, 8-hour time-weighted average. This study demonstrates that routine spray-buffing and wet-stripping of asbestos-containing resilient floor tile can result in elevated levels of airborne asbestos. Greater releases of airborne asbestos were observed during wet-stripping than during spray-buffing. The results of this study further suggest that multiple layers of sealant applied to the f...

Delineating landfill leachate discharge to an arsenic contaminated waterway

Discharge of contaminated ground water may serve as a primary and on-going source of contamination to surface water. A field investigation was conducted at a Superfund site in Massachusetts, USA to define the locus of contaminant flux and support source identification for arsenic contamination in a pond abutting a closed landfill. Subsurface hydrology and ground-water chemistry were evaluated in the aquifer between the landfill and the pond during the period 2005-2009 employing a network of wells to delineate the spatial and temporal variability in subsurface conditions. These observations were compared with concurrent measures of ground-water seepage and surface water chemistry within a shallow cove that had a historical visual record of hydrous ferric oxide precipitation along with elevated arsenic concentrations in shallow sediments. Barium, presumably derived from materials disposed in the landfill, served as an indicator of leachate-impacted ground water discharging into the cove. Evaluation of the spatial distributions of seepage flux and the concentrations of barium, calcium, and ammonium-nitrogen indicated that the identified plume primarily discharged into the central portion of the cove. Comparison of the spatial distribution of chemical signatures at depth within the water column demonstrated that direct discharge of leachate-impacted ground water was the source of highest arsenic concentrations observed within the cove. These observations demonstrate that restoration of the impacted surface water body will necessitate control of leachate-impacted ground water that continues to discharge into the cove.

Remediation of MTBE from drinking water: air stripping followed by off-gas adsorption.

Abstract The widespread use of methyl tertiary butyl ether (MTBE) as an oxygenate in gasoline has resulted in the contamination of a large number of ground and surface water sources. Even though air stripping has been proven to be an effective treatment technology for MTBE removal, off-gas treatment often is required in conjunction with it. This study evaluated the combined treatment technologies of air stripping followed by off-gas adsorption on a pilot scale for the treatment of MTBE-contaminated water. The effect of air/water ratios on the treatment efficiency was studied, and the mass transfer coefficient was determined. Air/water ratios of 105:1, 151:1, 177:1, 190:1, 202:1, and 206:1 were used, and a treatment efficiency of >99% was achieved for all the runs conducted. The depth of packing required to achieve maximum treatment efficiency decreased with increasing air/water ratio. Relative humidity (RH) impacts on the MTBE adsorption capacity of a granular activated carbon (GAC) and carbonaceous resin were determined from pilot plant studies. Breakthrough profiles obtained from the pilot plant studies conducted at 20, 30, and 50% RH indicated that GAC has a higher adsorptive capacity than resin. The adsorptive capacity of GAC decreased with increasing RH, whereas RH did not impact the resin adsorptive capacity.

ASBESTOS EXPOSURES DURING ROUTINE FLOOR TILE MAINTENANCE. PART 2: ULTRA HIGH SPEED BURNISHING AND WET-STRIPPING

Abstract This study was conducted to evaluate airborne asbestos concentrations during ultra high speed (UHS) burnishing and wet-stripping of asbestos-containing resilient floor tile under two levels of floor care condition (poor and good). Airborne asbestos concentrations were measured by transmission electron microscopy (TEM) before and during each floor care maintenance procedure in the breathing zone of the custodial personnel. Airborne total fiber concentrations were also measured by phase contrast microscopy (PCM) for comparison with the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) of 0.1 f/cm3, 8-hour time-weighted average (TWA). This study shows that UHS burnishing and wet-stripping of asbestos-containing resilient floor tile can result in elevated levels of airborne asbestos. UHS burnishing and wet-stripping produced similar increases in airborne asbestos concentrations when compared with baseline measurements. Approximately 99.5 percent of the asbestos str...

A systematic scanning electron microscopy technique for evaluating combined biological/granular activated carbon treatment processes

Abstract A systematic scanning electron microscope analytical technique has been developed to examine granular activated carbon used as a medium for biomass attachment in liquid waste treatment. The procedure allows for the objective monitoring, comparing, and trouble shooting of combined processes by direct visual examination of the biomasss attachment characteristics and rating key criteria that have been found to have the greatest effect on the processs performance. These criteria include the surface characteristics of the carbon; the quantity, type, and position of the biomass; and the amount of unidentifiable material. A set of instructions along with a set of reference photographs that illustrate the rating scale of each criteria were developed as was a standard data recording form. Several investigators rated samples from a variety of bioreactors to verify the practicality and quality of the technique. A comparison of the individual ratings indicated a significant correlation with each other as w...

Evaluation of a sustainable remediation option: Beneficial reuse of petroleum-contaminated sediment as an energy source

The characteristics of petroleum-contaminated sediment (PCS) have been evaluated to assess whether the practice of its beneficial reuse as a sole or supplemental energy source is sustainable relative to other sediment remediation options such as monitored natural recovery (MNR), capping, or off-site disposal. Some of these remediation options for PCS are energy-intensive and/or require land utilization. The energy and compositional analysis results indicate a low carbon content (15–17%(wt)) and corresponding low energy values of 5,200 kJ/kg (2,200 Btu/lb) to 5,600 kJ/kg (2,400 Btu/lb). However, given other decision-making criteria, the sediment may contain enough value to be added as a supplemental fuel given that it is normally considered a waste product and is readily available. The thermogravimetric profiles obtained under both combustion and pyrolytic conditions showed that the sulfur contents were comparable to typical low sulfur bituminous or lignite coals found in the United States, and most of the volatiles could be vaporized below 750°C. The heavy metal concentrations determined before and after combustion of the PCS indicated that further engineering controls may be required for mercury, arsenic, and lead. Due to the potential for reduction of public health and environmental threats, potential economic savings, and conservation of natural resources (petroleum and land), removal of PCS by dredging and beneficial reuse as a supplemental fuel clearly has merit to be considered as a sustainable remediation option. Implications: This study will provide a logical evaluation process to determine whether petroleum-contaminated sediment can be reused as an energy source. The energy and emissions values were determined and evaluated whether the sediment could be combusted for viable and sustainable use, considering several factors pertinent to evaluate in the remediation decision process. Various analysis methods were employed to determine elemental compositions, heating values, thermal and emission characteristics. This evaluation process may be used as a general methodology for the determination of petroleum-contaminated sediment as a supplemental fuel that may have merit to be considered as a sustainable remediation option.

Measurement of Subcellular Ions by X-ray Microanalysis for Evidence of Hepatotoxicity

This chapter is largely an elaboration of a paper which was presented at the Forensic, Occupational and Environmental Health Symposium at the 1985 joint national meetings of the Electron Microscopy Society of America and the Microbeam Analysis Society in Louisville, Kentucky. An extended abstract of that presentation has been published by San Francisco Press.

Liver Tissue Preparation Using a Modified Cryoultramicrotomy Kit

The great potential of cryoultramicrotomy is that it is possible to observe the morphology of a sample in the electron microscope while at the same time analyze for its elemental composition using x-ray microanalysis. There are other methods using indirect means of studying the chemical composition of cell organelles, such as digestion and centrifugation, but cryoultramicrotomy is the only direct method. This unique ability will make cryoultramicrotomy a vital tool in the field of cell biology and pathology in the near future. Our interest is the quantitative analyses of diffusible elements in the mitochondria of rat liver before and after exposure to toxins both singularly and in mixtures. To obtain reliable and reproducible data it is critical that each step in the technique be carried out correctly. Any deviation in any of the steps will leave the final results in doubt.