Vapor intrusion (VI) is the process by which chemicals, usually volatile organic compounds (VOCs), in soil or groundwater migrate to indoor air above or around a contaminated site. [1] The process of VI has been studied more recently in relation to its effects on humans and the environment, and is becoming more regulated by the United States Environmental Protection Agency (US EPA).
The United States Environmental Protection Agency defines vapor intrusion as "a migration of volatile chemicals from groundwater contamination or contaminated soil into an overlying building". [2] The chemicals can be of different classes including volatile organic compounds (VOCs), certain semi-volatile organic compounds (SVOCs) [3] and inorganic chemicals, such as elemental mercury, polycyclic aromatic hydrocarbons (PAHs), naturally occurring radon, and hydrogen sulfide. [2]
Vapor intrusion is mainly caused by nearby chemical usage and improper cleanup of brownfield sites. This allows these chemicals to seep into soil or groundwater, and eventually end up in overhead building air. VOCs are most able to travel through porous soils because of the space it allows for the chemicals, and then diffuse in the vadose zone of soil, [4] eventually to areas underneath manmade structures and buildings. Once under building foundation, the processes of advection and diffusion [4] are responsible for the compounds traveling through cracks of the foundation until the gaseous compounds mix with the components of the indoor air. The ability of the compound to enter a building through advectio can be related to the pressure gradient of the soil versus the building, which is caused by the 'stack effect' of the foundation. "Preferential pathways" affect the process of vapor intrusion. Preferential pathways, such as elevator shafts, pipes, and storm drains, act as an easy path for VOCs to travel through via groundwater or soil gas, and enter a building through man-made entrances like vents and faucets. The usage of preferential pathways for vapor intrusion can be mitigated with well-kept sewer and pipe systems that do not allow contamination through cracks, leaks, and holes. [1]
Vapor intrusion can be a cause for concern when chemicals seep into areas of human residence or work. When these chemicals mix with the indoor air, they can lead to acute or chronic health problems, like headaches, mental status changes, and increased risk of certain cancers. Vapor intrusion can also pose a threat when an infiltrated building contains flammable materials, as many VA compounds can act as a catalyst to cause an explosion.
With this said, it is important mitigation strategies are put in place where there is high risk of VOC intrusion (within 100 feet of a contaminant). In 2012, the EPA released a "Citizens Guide to Vapor Intrusion", where different mitigation methods are explained. Two methods in particular are described, sub-slab depressurization, which entails using a fan to vent chemical vapors outdoors, and the over-pressurization of buildings, in which building pressure is increased to decrease the pressure gradient between under the building and the inside of the building. For larger buildings, an architectural mitigation strategy that is noted to decrease the likelihood of chemicals traveling into indoors is large, ventilated structures being installed under buildings. These structures, such as parking garages, will allow the gaseous chemicals to disperse in outside air rather than traveling directly indoors.
In the United States, vapor intrusion is handled in individual states in different ways. Pathbreaking guidance on vapor intrusion was released by the New York Department of Health in 2006. [5]
In June 2010, the American Society for Testing and Materials (ASTM International) released a commercial "Standard Guide for Vapor Encroachment Screening on Property Involved in Real Estate Transactions" (ASTM E 2600–10). [6]
In 2002 the US EPA had issued its first draft guidance on the subject. [7] The George W. Bush administration dropped the project in 2003, and only in 2013 did Obama's appointee as EPA Assistant Administrator in the Office of Solid Waste and Emergency Response make it a priority to complete the document. On June 11, 2015, the EPA released its final Vapor Intrusion Technical Guide, along with a Technical Guide for Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites. A guide is neither a statute nor a regulation, but a guidance. [8]
TRW Inc., was an American corporation involved in a variety of businesses, mainly aerospace, electronics, automotive, and credit reporting. It was a pioneer in multiple fields including electronic components, integrated circuits, computers, software and systems engineering. TRW built many spacecraft, including Pioneer 1, Pioneer 10, and several space-based observatories. It was #57 on the 1986 Fortune 500 list, and had 122,258 employees. The company was called Thompson Ramo Wooldridge Inc., after the 1958 merger of the Ramo-Wooldridge Corporation and Thompson Products. This was later shortened to TRW.
Environmental remediation is the cleanup of hazardous substances dealing with the removal, treatment and containment of pollution or contaminants from environmental media such as soil, groundwater, sediment. Remediation may be required by regulations before development of land revitalization projects. Developers who agree to voluntary cleanup may be offered incentives under state or municipal programs like New York State's Brownfield Cleanup Program. If remediation is done by removal the waste materials are simply transported off-site for disposal at another location. The waste material can also be contained by physical barriers like slurry walls. The use of slurry walls is well-established in the construction industry. The application of (low) pressure grouting, used to mitigate soil liquefaction risks in San Francisco and other earthquake zones, has achieved mixed results in field tests to create barriers, and site-specific results depend upon many variable conditions that can greatly impact outcomes.
Volatile organic compounds (VOCs) are organic compounds that have a high vapor pressure at room temperature. High vapor pressure correlates with a low boiling point, which relates to the number of the sample's molecules in the surrounding air, a trait known as volatility.
An underground storage tank (UST) is, according to United States federal regulations, a storage tank, including any underground piping connected to the tank, that has at least 10 percent of its volume underground.
In the United States, an environmental site assessment is a report prepared for a real estate holding that identifies potential or existing environmental contamination liabilities. The analysis, often called an ESA, typically addresses both the underlying land as well as physical improvements to the property. A proportion of contaminated sites are "brownfield sites." In severe cases, brownfield sites may be added to the National Priorities List where they will be subject to the U.S. Environmental Protection Agency's Superfund program.
Soil vapor extraction (SVE) is a physical treatment process for in situ remediation of volatile contaminants in vadose zone (unsaturated) soils. SVE is based on mass transfer of contaminant from the solid (sorbed) and liquid phases into the gas phase, with subsequent collection of the gas phase contamination at extraction wells. Extracted contaminant mass in the gas phase is treated in aboveground systems. In essence, SVE is the vadose zone equivalent of the pump-and-treat technology for groundwater remediation. SVE is particularly amenable to contaminants with higher Henry’s Law constants, including various chlorinated solvents and hydrocarbons. SVE is a well-demonstrated, mature remediation technology and has been identified by the U.S. Environmental Protection Agency (EPA) as presumptive remedy.
AMCO Chemical was a chemical distribution company located in Oakland, California. The land the company operated on is designated as a U.S. Environmental Protection Agency (EPA) Superfund cleanup site.
Havertown Superfund is a 13-acre polluted groundwater site in Havertown, Pennsylvania contaminated by the dumping of industrial waste by National Wood Preservers from 1947 to 1991. The state first became aware of the pollution in 1962 and initiated legal action against the owners in 1973 to force them to cleanup the site. The Environmental Protection Agency (EPA) ranked the site the eighth worst cleanup project in the United States. The site was added to the National Priorities List in 1983 and designated as a Superfund cleanup site in the early 1990s. Remediation and monitoring efforts are ongoing and the EPA transferred control of the site to the Pennsylvania Department of Environmental Protection in 2013.
Electrical resistance heating (ERH) is an intensive in situ environmental remediation method that uses the flow of alternating current electricity to heat soil and groundwater and evaporate contaminants. Electric current is passed through a targeted soil volume between subsurface electrode elements. The resistance to electrical flow that exists in the soil causes the formation of heat; resulting in an increase in temperature until the boiling point of water at depth is reached. After reaching this temperature, further energy input causes a phase change, forming steam and removing volatile contaminants. ERH is typically more cost effective when used for treating contaminant source areas.
The American Creosote Works Superfund site is an inactive wood-treating facility in Pensacola, Florida. The 18-acre site is located about 600 yards north of the confluence of Bayou Chico and Pensacola Bay at 701 S "J" Street. The Superfund program of the United States Environmental Protection Agency (EPA) is responsible for cleaning up the nation's most contaminated land and responding to environmental emergencies, oil spills, and natural disasters.
The environmental effects of paint can vary depending on the type of paint used and mitigation measures. Traditional painting materials and processes can have harmful effects on the environment, including those from the use of lead and other additives. Measures can be taken to reduce its environmental effects, including accurately estimating paint quantities so waste is minimized, and use of environmentally preferred paints, coating, painting accessories, and techniques.
Pemaco is a former chemical mixing company and facility located on the Los Angeles River in Maywood, a small city in southeastern Los Angeles County, California.
The Omega Chemical Corporation was a refrigerant and solvent recycling company that operated from 1976 to 1991 in Whittier, California. Due to improper waste handling and removal, the soil and groundwater beneath the property became contaminated and the area is now referred to as the Omega Chemical Superfund Site. Cleanup of the site began in 1995 with the removal of hazardous waste receptacles and a multimillion-dollar soil vaporization detoxifying system.
The Del Amo Superfund Site is located in southern Los Angeles County between the cities of Torrance and Carson. It is a U.S. EPA Region 9 Superfund Site. The waste-disposal site of a rubber manufacturer is one of 94 Superfund Sites in California as of November 29, 2010.
The Waste Disposal Inc. Superfund site is an oil-related contaminated site in the highly industrialized city of Santa Fe Springs in Los Angeles County, California. It is approximately 38 acres (15 ha), with St Paul's high school immediately adjacent to the northeast corner of the site. Approximately 15,000 residents of Santa Fe Springs obtain drinking water from wells within three miles (4.8 km) of the site.
Air sparging, also known as in situ air stripping and in situ volatilization is an in situ remediation technique, used for the treatment of saturated soils and groundwater contaminated by volatile organic compounds (VOCs) like petroleum hydrocarbons, a widespread problem for the ground water and soil health. Vapor extraction has become a very successful and practical method of VOC remediation. In saturated zone remediation, air sparging refers to the injection a hydrocarbon-free gaseous medium into the ground where contamination has been found. When it comes to situ air sparging it became an intricate phase process that was proven to be successful in Europe since the 1980s. Currently, there have been further developments into bettering the engineering design and process of air sparging.
Emmell's Septic Landfill (ESL) is located at 128 Zurich Ave, Galloway Township, New Jersey and takes up about 38 acres of space. The landfill was in operation from 1967 until 1979. ESL disposed of liquid and solid waste including many chemicals such as volatile organic compounds (VOCs), Polychlorinated Biphenyls (PCBs), Trichloroethene and Vinyl chloride which all had their own effect on the environment and community. These chemicals affected the groundwater required millions of dollars to reconstruct the groundwater pathways and provide clean water to residents. The landfill holds a Hazardous Ranking Score of a 50/100, qualifying for the Superfund National Priority List. In August 1999, the state acknowledged the site's contamination and held town meetings and provided research upon the site such as groundwater samples. In July 1997, a sitewide investigation was called upon by the United States Environmental Protection Agency. In total the clean up was estimated to cost $5 million to fund this superfund site, and a grant of $3.9 million was given by the Federal Government under the Recovery Act Funding (Previti). Today, the project is still ongoing however, greatly improved since the landfill was discovered.
The Diamond Head Oil Refinery is a former oil reprocessing facility located in Kearny, New Jersey, United States, that was designated as a Superfund site by the Environmental Protection Agency (EPA). It opened up in 1946, but then stopped production in 1979 and has been inactive since then. The refinery was shut down in 1980 and the EPA designated it as a Superfund site in 1991 due to the discovery of toxic chemicals in the soil and the surface water. This created a dangerous work environment for the workers at the facility. The EPA proposed a clean up plan for the site, but it has yet to take effect. So far, the Diamond Head site is still in the process of being cleaned up. Although cleanup plans were discussed and finalized, the future of the Diamond Head Oil Refinery and its cleanup state is unknown.
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