Existing contaminated sites, environmental

EPA uses its authority under the Comprehensive Environmental Response. Compensation, and Liability Act (commonly known as "Superftind") to set standards for the clean-up of existing contaminated sites. Cleanups must meet all environmental requirements that are relevant or applicable, including state regulations and regulations issued in connection with other federal environmental laws. 

Bioremediation systems in operation today rely on microorganisms indigenous to contaminated sites. The two main approaches, based on the actions of native microbial communities, are biostimulation and intrinsic bioremediation. In biostimulation, the activity of native microbes is encouraged, creating (in situ or ex situ) the optimum environmental conditions and supplying nutrients and other chemicals essential for their metabolism. The vast majority of bioremediation projects are based on this biostimulation approach. Intrinsic bioremediation is a remedial option that can be applied when there is strong evidence that biodegradation will occur naturally over time without any external stimulation i.e., a capable microbial community exists at the site, the required nutrients are available, and the environmental conditions are favorable. An additional prerequisite is that the naturally... 

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). This is an attempt to deal with the many waste sites that exist across the nation. It covers remedial action, including the establishment of a National Priorities List to identify those sites that should have a high priority for remediation. This act authorizes the cleanup of hazardous waste sites, including those containing pesticides, that threaten human health or the environment. If they can be identified, the US EPA is authorized to recover cleanup costs from those parties responsible for the contamination. CERCLA provides a fund to pay for the cleanup of contaminated sites when no other parties are able to conduct the cleanup. The Superfund Amendments and Reauthorization Act (SARA) (1986) is an amendment to CERCLA that enables the US EPA to identify and cleanup inactive hazardous waste sites and to recover reimbursement of cleanup costs. One section of CERCLA authorizes the EPA to act whenever there is a release or substantial threat of release of a hazardous substance or any pollutant or contaminant that may present an imminent or substantial danger to the public health or welfare into the environment. 

Where contaminated sites exist, information about historical industrial activities can often be obtained from environmental protection agencies. Such disused sites may continue to pollute drinking-water sources for many years or decades after the industry has closed down if residual soil contamination at the site has not been cleaned up,... 

The applications of separation science to environmental restoration are centered on the cleanup of contaminated groundwaters and soils. The extent and complexity of the groundwater contamination problem continues to present formidable technological obstacles to cleanup. The most important factors that contribute to this complexity are the large number of contaminated sites, the wide diversity of the contaminants present in those sites, the Inherent complexity of the subsurface chemistry of the contaminants, and the difficulty in interpreting existing regulations to establish compliance and properly prioritize site remediation efforts. 

From a regulatory perspective, abandoned landfills are abandoned and inactive waste disposal sites, regardless of the point in time at which they were rendered inactive, illegal waste disposal sites that existed before the enactment of the respective waste laws (so-called illegal dumps ) and other abandoned/inactive dumps or fills whereas abandoned contamination sites are sites of inactive installations that handled environmentally hazardous substances (i.e., these are primarily old industrial and commercial facilities). 

Collecting and analyzing existing data. Existing data (Table 16.1) are collected and analyzed to develop a conceptual site model that can be used to assess both the nature and the extent of contamination and to identify potential exposure pathways and potential human health or environmental receptors. 

Free-phase NAPL refers to NAPL that exists as an independent phase, not as a dissolved component in the pore water or pore atmosphere. The environmental concerns associated with sites affected with free-phase NAPLs revolve around hydrocarbon-impacted soil (residual hydrocarbon), the NAPL itself (which can serve as a continued source for groundwater contamination), dissolved hydrocarbon constituents in groundwater, and hydrocarbon vapors. The detection of free-phase NAPLs in the subsurface presents many challenges. Two questions frequently arise at sites impacted by NAPLs how much is there and how long will it take to clean up. Before one can address these two questions, assessments of the type and subsurface distri-... 

Pressly Associates, Inc., an environmental consulting firm in Brookhaven, New York, researched treatment options (including PF) for a dry cleaner site contaminated with tetra-chloroethene (PCE). According to the firm, a 2-acre plume exists at the site to a depth of 35 ft below ground surface (bgs) (or 30 ft below the water table). Soils at the site consist of fine to medium sand, silt, and sand and gravel. The firm claims that capital costs for various treatment options are as follows ... 

The ability to rapidly assess or monitor the disposition of environmental contaminants at purported or existing hazardous waste sites is an essential component of green chemistry. Soil samples, which represent approximately half the total number, are extracted with solvents, and then further separated using additional solvent to produce chemical-specific fractions. Each fraction is then analyzed using an appropriate method. The new technology proposed at the Tufts... 

Existing site information very likely comes from the initial site assessment or phase I Environmental Site Assessment (ESA) done for that site. A phase I ESA normally includes a site inspection, a review of the relevant data, interviews, and a written report. When a phase II ESA is performed, more existing site information is obtained. A phase II contains (limited) soil sampling, done to determine the soil contaminants, or to determine the soil quality on- and off-site. Phase II ESAs have written reports including recommendations and have the extent of contamination delineated. 

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