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A major portion of northern Virginia is underlain by a quartz-muscovite soil, on average about 10 meters thick, that has developed on a bedrock of polymetamoirphic schist. The schist formed from an ancient clay-rich sediment eventually recrystallized several times, as the modern Appalachian rocks were heated deep in the Earth and subsequently exposed by erosion. The total gamma radioactivity and the permeability of the schist are higher than average, and combine to generate a radon-rich soil-gas that can be brought into homes by the pressure differential normally present in local homes that commonly are well insulated and have basements. More than half of the homes, based on three-month measurements, exceed the U.S. Environmental Protection Agency recommended maximum for indoor radon of 4 pCi/L. Fortunately, while the area is experiencing a rapid inc rease in new home construction, it is possible to avoid types of home construction susceptible to, and areas of, high soil-gas radon and high permeability.

In a recent study of about 700 homes in Virgin ia and Maryland, three-month measurements of airborne radon derived from soil-gas combined with indoor radon derived from potable water in the home ranged from about 10–40 pCi/L. The radon in the potable water ranged from less than 100 to 8000 pCi/L/L. The home sizes ranged from about 20,000 to 100,000 cubic feet. In a study set composed of all the homes using water with low concentrations of waterborne radon, no correlation was observed between indoor radon and home size. In study sets of increasingly high waterborne radon, a correlation can be seen between waterborne radon and indoor radon. As the waterborne radon increases, smaller homes tend to have more indoor radon than larger homes. In terms of the risk of developing lung cancer, the greatest risk is experienced by people using well water while living in small homes.

The standard practice currently used by state and federal regulatory agencies for remedial action has been proven to be very costly, time consuming and labor intensive. To improve project quality and to save resources, the U.S. Environmental Protection Agency has initiated a Triad approach that integrates systematic project planning, dynamic work strategies and real-time measurement technologies for the management of environmental projects. The central principle of the Triad approach is managing decision uncertainty. Experience from several previous investigations has shown significant savings in time and costs by using Triad approach, while providing more reliable scientific data for decision-making. The Sampling, Characterization and Monitoring Team of the Interstate Technology Regulatory Council has completed a Technical and Regulatory Guidance document summarizing the principles of the Triad approach and the scientific and technical requirements to employing this paradigm shift. The advantages of adapting this innovative approach in hazardous waste site investigation and remediation will be highlighted.

Organoclays have been used as a pre-polisher for activated carbon, or post-polisher for oil/water separators and DAF units, for the removal of small amounts of oil, grease, PCB, PNA, BTX and other organic hydrocarbons of low solubility for the cleanup of groundwater and wastewater. The end user can save 50% or more of his operations costs by removing large hydrocarbons which plug the pores of activated carbon beforehand, allowing carbon to remove the last 5 ppm or less of volatile compounds. Organoclays can remove 7 times as much oil and other organic hydrocarbons of low solubility, as does carbon.

This article describes what organoclay is, how it is used, and presents several case histories of large systems at military bases and other places.

A multi-faceted remedial program was implemented at a former locomotive fueling area (FLFA) at a rail yard in upstate New York to address diesel-affected soil and groundwater. Main line tracks running through the FLFA prohibited removal of affected soil and, consequently, an remedy was developed. The remedy combines air sparging to provide oxygen to intrinsic diesel-degrading microorganisms and to volatilize petroleum compounds, and soil vapor extraction to actively remove volatilized diesel compounds from the subsurface. System components include vapor extraction and air sparging wells within the FLFA and low-flow biosparging wells between the FLFA and down gradient properties. The biosparging wells create an oxygen barrier to migrating diesel compounds. Based on vapor extraction flow rates and the concentration of volatile organic compounds (VOCs) in extracted air, an estimated 1,000 pounds of petroleum mass have been removed by the vapor extraction system to date. Mass removal and biological activity is strongly correlated with seasonal fluctuations in subsurface temperature, which varies by more than eight degrees Celsius in the treatment zone over the course of a year. Analyses of microbial biomass in the treatment area indicate that diesel-degrading organisms increased by four orders of magnitude in unsaturated soil and by three orders of magnitude in saturated soil within five months of system start up. Regulated VOC and semi-volatile organic compound (SVOC) concentrations in soil decreased in subsurface soil to below detection limits in most locations in approximately 24 months. Concentrations of petroleum compounds in groundwater have been reduced to less than regulatory standards over the majority of the site and have declined 84 percent on average. This integrated approach to the treatment of diesel-impacted soil and groundwater has greatly reduced cleanup costs and cleanup time for the site.

Two subspecies of L. (summer squash) differ in phyto-extraction of weathered DDE when grown in the field. Three cultivars were selected from each of the two subspecies; ssp (zucchini) with a greater ability to take up DDE, and ssp (summer squash) with a lesser ability to take up DDE. When grown in the field, ssp extracted 0.4 to 1.0 milligrams of DDE per plant, while ssp removed from the soil only 0.02 to 0.1 milligram per plant. These cultivars were grown in hydroponics to evaluate whether exudation of organic acids from the roots was involved in uptake of weathered DDE. Phosphorus nutrition played a significant role in exudation of organic acids into the hydroponics solution. For both subspecies, the better the phosphorus nutrition, the more tartaric and less citric acid was exuded. Subspecies showed a greater increase in citric acid exuded under phosphorus depletion than . However, when solutions of root exudates were used to batch extract DDE from soil, effect of subspecies was opposite to that seen in the field. This suggests there are factors other than disruption of the soil matrix that play a role in phyto-extraction by plants. Nevertheless, among subspecies of , the exudation of citric acid was related to phyto-extraction of more weathered organic contaminants in soil.

Lead contamination in the urban environment is a continuing serious public health concern. Historically lead entered the urban residential area though paint pigment and gasoline additives. This legacy persists as the two most important lead sources that affect children in the urban environment: contaminated paint residue and contaminated soil. One technique for remediation of lead in urban soils is phytoremediation. Previous research has shown Brassica juncea, Indian mustard, to be a promising phytoremediator of lead in soil. Researchers commonly use broad leafed mustard such as Southern Giant Curly Leaf, because it is an accumulator of lead, has extremely high production of mustard green biomass in a short growing season, and is adaptable to poor soil conditions. The authors believe that use of broadleaf mustard in the urban environment may be problematic. The greens are enjoyed as a food, are easily recognized, and may be pilfered and eaten. This research tested the hypothesis that seed mustard, which produces abundant flowers but few greens, would be more suitable. Two 64 m plots were prepared in a Greater Rochester Urban Bounty garden, located at a busy intersection in Rochester New York’s low-income northeast neighborhood. One plot was sown thickly with Southern Giant, and the other with seed mustard. As the plants approached maturity the entire crop of Southern Giant mustard was pilfered, but the seed mustard remained untouched. At maturity the seed mustard produced 550g dry biomass per m . Subsequent testing included germination of seed mustard in lead-contaminated soil, and trials to determine maximum biomass production using seed mustard by varying planting density. Results indicate no detriment to germination rate, and a maximum biomass production capacity approaching 7 Kg/m

An chemical oxidation (ISCO) pilot program, using Fenton’s Reagent (hydrogen peroxide and a ferrous sulfate catalyst), was performed to assess its effectiveness in destroying chlorinated volatile organic compounds (CVOCs) in a fractured-bedrock aquifer. This case study is unique because it was one of the first applications of ISCO in fractured bedrock. In addition, the targeted CVOC reduction from 1,500 to 100 micrograms per liter (μg/L) was relatively aggressive compared to most ISCO applications. This pilot program also provided the opportunity for an independent, third party evaluation of ISCO in a fractured-bedrock environment. The site geology consists of approximately 6 meters (m) of unconsolidated glacial deposits overlying fractured bedrock, with a groundwater depth of approximately 2 m. Initial characterization activities, including injection testing and multi-level packer sampling, identified a pre-ISCO CVOC plume extending approximately 90 m long by 45 m wide and spanning a vertical depth between 3 and 35 m. Packer sampling results indicated the pre-ISCO plume had an asymmetric configuration that was consistent with the injection-test results. The ISCO pilot program involved the injection of 14,237 liters of 50% hydrogen peroxide, combined with a ferrous sulfate and pH-buffering catalyst. Two injection events were performed, with overlapping performance sampling. Samples collected 30 to 45 days after each injection event showed CVOC concentrations below the treatment objective in many areas of the plume. However, samples collected 60 to 100 days after each event revealed significant rebound in most areas, at concentrations that approached initial pre-ISCO aquifer conditions. An assessment of the results suggests that the injected oxidants primarily influenced the more transmissive fractures in the treatment zone, whereas the less transmissive fractures were less influenced. Geochemical data and calculations indicate that the peroxide and catalyst may persist in the subsurface for prolonged periods (>200 days), thus complicating the assessment of rebound and the actual effectiveness of the technology. Although the success of treatment was limited, it proved to be successful in enhancing the conceptual site model of the subsurface, better defining the applications and limitations of ISCO treatment in fractured bedrock, and most importantly, clearly identifying the source of residual CVOCs at the site.

The reaction chemistry of ISCO is presented for the common oxidant systems employed in ISCO: catalyzed peroxide propagations (Modified Fenton’s), persulfate, ozone/ozone-peroxide (peroxone), and permanganate. All of these oxidant systems, with the exception of permanganate are described by reaction schemes employing free radical generation, and all are dependent to some degree on local conditions such as water chemistry and pH. A less familiar reactant condition may be the influence of inorganic and organic compounds in the soil matrix, which can have a strong influence over the intended outcome of the ISCO application. Thus, naturally occurring organic compounds may overwhelm the contaminant demand for oxidant or prevent the transition of the adsorbed contaminant to the aqueous phase where ISCO reactions occur. Naturally occurring inorganic compounds may actu ally cause destruction of the oxidant or modify the catalytic component. Some experience with soils having markedly different matrix properties are discussed to provide an illustration of some of the difficulties which may be faced in the practice of ISCO.

This paper describes how the Massachusetts Brownflelds process was implemented at the Oxford Paper Mill Site in Lawrence, Massachusetts. The City employed a dynamic process where the community, City, and regulators developed a detailed plan to address integration of stakeholder schedules and provide the necessary monies to remediate a three acre Brownfield site. Successful implementation of this complex process is allowing the City to abate contamination, develop a large-scale park, and construct the Gateway Bridge. This is considered integral to future development of Lawrence.

Significant stakeholders include the City of Lawrence, Massachusetts Department of Environmental Protection (MDEP), Massachusetts Highway Department (MHD), the Environmental Protection Agency (EPA ), Mass Development, and Community Action Groups.

Contaminants of concern at the site include asbestos, PCBs and PAHs. On site concentrations of PCBs significantly exceed the EPA and Massachusetts Contingency Plan (MCP) cleanup goals.

The challenges for this project include assisting the City in obtaining sufficient funding, coordinating with the abutting property owner cleanup of the raceway (man-made waterway) that runs through the site, and coordinating areas of remediation with MHD and the City.