Contaminated Sites

Abstract

Soil, groundwater, surface water, and air at contaminated sites may contain chemicals that could cause harm to human health or the environment. Spills, leaks, or other mismanagement of chemicals cause this contamination. Once a site is contaminated, it is very difficult, expensive, and sometimes impossible to clean up. During the modern environmental movement in the 1960s, awareness of the risks from contaminated sites increased. After the first high profile contaminated site, Love Canal, resulted in emergency declarations by President Jimmy Carter in 1978 and 1980, the federal Comprehensive Environmental Response Compensation and Liability Act, or Superfund, was passed to address the nation’s highest risk contaminated sites. Since then, the technical expertise required for discovering, understanding, investigating, cleaning up, and redeveloping contaminated sites has advanced considerably. A case history of the Woolfolk Chemical Works Superfund site demonstrates the importance of community involvement and consideration of environmental justice during the investigation and cleanup of contaminated sites. Although continued technical advances are needed to improve the investigation and cleanup of contaminated sites, more emphasis is needed on predicting the future environmental impact of current innovations to prevent the continued creation of new contaminated sites.

1 Introduction

Chemicals are present at contaminated sites in the soil, groundwater, surface water, and/or air at levels that could cause harm to human health or the environment. Contaminated sites such as industrial facilities or the corner gas station become contaminated from spills, leaks, or other mismanagement of chemicals. Although contaminated sites have been present in the United States since the Industrial Revolution, their risks to human health and the environment did not become evident until the modern environmental movement began in the 1960s. This movement raised awareness of environmental issues and led to the passage of key federal environmental regulations in the 1970s and 1980s. After the first high profile contaminated site, Love Canal, resulted in emergency declarations by President Jimmy Carter in 1978 and 1980, the federal Comprehensive Environmental Response Compensation and Liability Act, or Superfund, was passed to address the nation’s highest risk contaminated sites. Since then, the technical expertise required for discovering, understanding, investigating, cleaning up, and redeveloping contaminated sites has advanced considerably. Community involvement during the investigation and cleanup of contaminated sites as well as consideration of environmental justice issues are critically important, yet often overlooked, aspects of successfully addressing contaminated sites. The importance of these aspects is illustrated in a case history of the Woolfolk Chemical Works Superfund site along with the technical aspects of the site discovery, understanding, investigation, cleanup, and redevelopment.

Contaminated sites are often created because the future environmental impact of current practices is unknown; our ability to innovate far exceeds our ability to predict the environmental impact of our innovations. Even with the significant technological advances that have been made in the last 50 years, once a site is contaminated, it is still very difficult, expensive, and sometimes impossible to restore to its previously uncontaminated condition. Technical advances are needed not just to improve the investigation and cleanup of contaminated sites but also to better predict the environmental impact of new chemicals and products and prevent contamination from occurring.

2 Social Backdrop

The origins of the modern environmental movement are often traced to Rachel Carson [1]. As a biologist who spent 15 years working for the United States Fish and Wildlife Service, she had a deep understanding and love of the natural world. As a writer, she communicated the beauty of nature to a broad audience. When her third book, Silent Spring , was published in 1962, she warned about the long-term effects of the expanded use of synthetic chemical pesticides. She documented places in the United States where the use of pesticides, such as DDT, resulted in a spring without birds singing. Most importantly, she said that humans are a vulnerable part of the natural world subject to the same damage as the rest of the ecosystem [21].

Environmental conditions in the United States were threatening human health; leaded gasoline was releasing such high levels of lead into the air that the average preschooler had four times the currently allowable blood lead level, smog obscured the sun in many large cities, and waterways were so polluted that they could catch on fire.

After reading or hearing about these conditions and the grim future ahead if the country stayed on its current path, many Americans became concerned about the environment for the first time. Beginning with Rachel Carson’s dire warning, the 1960s became a decade of environmental awakening that ended with the first Earth Day in 1970 [22]. Senator Gaylord Nelson [24] of Wisconsin proposed the first Earth Day and wrote:

When April 22, 1970, dawned, literally millions of Americans of all ages and from all walks of life participated in Earth Day celebrations from coast to coast. It was on that day that Americans made it clear that they understood and were deeply concerned over the deterioration of our environment and the mindless dissipation of our resources. That day left a permanent impact on the politics of America. It forcibly thrust the issue of environmental quality and resources conservation into the political dialogue of the Nation. That was the important objective and achievement of Earth Day. It showed the political and opinion leadership of the country that the people cared, that they were ready for political action, that the politicians had better get ready, too. In short, Earth Day launched the Environmental decade with a bang.

The environmental movement of the 1960s led to the passage of environmental regulations that have been protecting our air, water, and land ever since.

3 Environmental Regulation

The creation of the United States Environmental Protection Agency (EPA) in 1970 was the beginning of a new emphasis on the environment that included passage of the following foundational environmental laws (Fig. 15.1):

• National Environmental Policy Act (NEPA) – Passed in 1969, this was one of the first laws that established the broad national framework for protecting the environment. NEPA requires all branches of the federal government to consider the environment prior to undertaking any major federal projects.

• Clean Air Act – In 1970 this comprehensive federal law was passed to regulate air emissions and authorize EPA to establish National Ambient Air Quality Standards to protect public health.

• Clean Water Act – Although the Federal Water Pollution Control Act of 1948 established basic water pollution control requirements, significant reorganization and expansion in 1972 created the current framework for regulating discharges of pollutants into waterways. Under the Clean Water Act, as it is now known, water quality standards are established with the goal of attaining fishable, swimmable waters throughout the United States.

Fig. 15.1

Timeline of environmental milestones

Following the establishment of these key environmental laws, attention turned to hazardous and solid waste. In 1976, Congress amended the Solid Waste Disposal Act of 1965 with the Resource Conservation and Recovery Act (RCRA) to address problems from a growing volume of municipal and industrial wastes. RCRA created “cradle to grave” hazardous waste management by authorizing EPA to control hazardous waste generation, transportation, treatment, storage, and disposal. RCRA also created a framework for the management of non-hazardous solid wastes in municipal landfills. In 1988, RCRA was amended to enable EPA to address environmental problems from underground storage tanks (USTs) storing petroleum and other hazardous substances because of widespread groundwater contamination from leaking USTs.

The severity of contamination at the infamous Love Canal site in Niagara Falls, New York, led to passage of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund, in 1980. This law created a tax on the chemical and petroleum industries for a trust fund (Superfund) for cleaning up abandoned or uncontrolled hazardous waste sites. It also provided broad federal authority to respond to releases of hazardous substances that could endanger public health or the environment. The Superfund enforcement program identifies companies responsible for contamination at a site, called Potentially Responsible Parties (PRPs), and orders them to clean up the site or pay for the cleanup to be completed by the EPA, a state, or another responsible party. CERCLA also created a National Priorities List (NPL), a national list of the highest risk sites that have priority for cleanup. Love Canal was the first Superfund site on that list [14].

4 Love Canal

In 1894, William T. Love began building a shipping canal in New York that would bypass Niagara Falls to provide inexpensive hydroelectric power for industrial development. However, only one mile of the canal was actually built before the project was abandoned. The excavation was partially filled with water and initially used for recreation until the 1920s when the City of Niagara Falls used the abandoned canal as a municipal landfill.

In the 1940s, Hooker Chemical was given permission to place industrial waste in the abandoned canal. After lining it with clay, Hooker Chemical disposed of more than 21,000 tons of drums containing chemical wastes over a 10-year period. The wastes included caustics, alkalines, fatty acids, and chlorinated hydrocarbons resulting from the manufacturing of dyes, perfumes, and solvents for rubber and synthetic resins. In 1953, the landfill was covered with clay and leased to the Niagara Falls Board of Education. An elementary school and many residential properties were built over the disposal area. These construction activities breached the clay cap and allowed rainwater to leach the chemicals.

During the 1960s, complaints about odors and residues were first reported at the Love Canal site. In the 1970s, complaints from residents living adjacent to the Love Canal landfill increased as rising groundwater levels brought contaminants to the surface. Various federal and New York State studies indicated that numerous toxic chemicals, including dioxin, had migrated through existing sewers and, ultimately, drained into nearby creeks. The EPA and New York State began investigating the Love Canal groundwater along with indoor air and sump water contamination in the various residences.

In 1978, after a dramatic increase in skin rashes, miscarriages, and birth defects among residents in the area, President Jimmy Carter issued the first of two emergency declarations regarding the Love Canal site. The first declaration provided federal funding for remedial work to contain the chemical wastes and to assist New York State in the relocation of some of the people living around the Love Canal landfill. This was the first time in American history that emergency funds were used for a situation other than a natural disaster.

In 1980, President Carter issued a second emergency declaration, establishing the 350-acre Love Canal Emergency Declaration Area surrounding the landfill. The second declaration authorized federal funds to purchase homes and relocate approximately 950 families under the management of the Federal Emergency Management Agency (FEMA) and New York State. The homes were demolished, and the demolition debris placed under the Love Canal landfill cap.

In 2004, after more than 20 years of work, EPA deleted the Love Canal Superfund site from the NPL. EPA, together with New York State, contained and secured the wastes disposed in the abandoned canal so that they are no longer leaking into surrounding soils and groundwater. The secured 70-acre site includes the original 16-acre hazardous waste landfill and a 40-acre disposal area covered by a synthetic liner with a clay cap and surrounded by a barrier drainage system with a leachate collection and treatment system.

Today, the Love Canal area is once again a flourishing community. Neighborhoods to the west and north of the canal have been revitalized, with more than 200 formerly boarded-up homes renovated and sold to new owners and ten newly constructed apartment buildings. The area east of the canal has been sold for light industrial and commercial redevelopment [15].

5 Contaminated Site Investigation/Remediation

5.1 Contaminated Sites

At contaminated sites, like Love Canal, chemicals are present in the soil, groundwater, surface water, and/or air at levels that could cause harm to human health or the environment. The chemicals could be toxins that cause cancer or naturally occurring chemicals that are present in unnaturally high concentrations due to human activities. These contaminated sites could be industrial facilities or the corner gas station. Sites become contaminated from spills, leaks, or other mismanagement of chemicals.

Contaminated sites are often created because the future environmental impact of current practices is unknown. For example, it was previously believed that disposing of waste in the ground was safe because the soil would filter out contaminants. Because of this mistaken belief, landfills and industrial wastewater lagoons were previously constructed without liners. Because of the soil and groundwater contamination that resulted from many unlined landfills and lagoons, current regulations require landfills and lagoons to be lined. Another common example of past practices that caused site contamination is gas stations. USTs containing gasoline at many gas stations have corroded and leaked fuel that caused soil and groundwater contamination that sometimes also resulted in hazardous vapors migrating into nearby buildings. This widespread problem resulted in stronger regulation and monitoring of underground fuel tanks. Regulations are just now being developed to address per- and polyfluoroalkyl substances (PFAS) manufactured and widely used for decades in non-stick coatings, fire-fighting foam, and many other products. Even though PFAS are now ubiquitous in the environment and the human body, research is still in progress to establish levels that are protective of human health and the environment. There are certainly other currently accepted practices that will cause future contaminated sites because our ability to innovate far exceeds our ability to predict the environmental impact of our innovations.

Not only are humans inadvertently causing contamination, but the ability to completely clean up contaminated sites is limited. Once a site is contaminated, it is very difficult – and often impossible – to completely restore the site to its previously uncontaminated condition. The most contaminated sites can require decades of significant effort costing millions of dollars to investigate and remediate. Even after that long-term commitment of time and money, there may still be residual contamination present requiring long-term monitoring and management. Rather than investing these resources in addressing a problem after it has been created, it would be preferable to invest time and money into preventing contamination from occurring in the first place. Figure 15.2 presents a schematic of a contaminated site, and the following paragraphs provide an overview of the complex process required to investigate and remediate contaminated sites.

Fig. 15.2

Contaminated site schematic

5.2 Discovery

Contaminated sites are often identified after complaints are made to state or federal agencies regarding conditions such as unusual odors, discolored streams, problems with drinking water, leaking drums, dead fish, and/or health problems in nearby residents. However, there are many other ways that contaminated sites can be identified. Permitted landfills, USTs, and other facilities that manage chemicals are required to conduct routine monitoring that may detect contamination. A facility that manages chemicals may accidentally spill or leak chemicals into the environment. Sometimes excavation during construction activities reveals odors, stained soil, and/or contaminated groundwater from a previously undiscovered contaminated site.

Due diligence prior to purchasing a property is now a common way that contaminated sites are identified. The owner of a property can be liable under CERCLA for cleaning up environmental contamination – even if a previous owner caused the contamination – unless they exercise due diligence in evaluating potential environmental issues prior to purchasing the property. Therefore, a Phase I Environmental Site Assessment (ESA) is almost always completed before a commercial or industrial property purchase to evaluate whether environmental problems are present on the property that could cause future liabilities. Sometimes these Phase I ESAs indicate potential contamination, and additional testing is conducted that confirms contamination.

When contamination is identified or suspected, state or federal environmental agencies must be notified. Investigation and remediation efforts will then be conducted under the oversight of the governmental agency.

5.3 Investigation

5.3.1 Source

Once a contaminated site is identified, investigation is required to define the scope of the problem beginning with the source of the contamination. Sometimes the investigation starts with a reported leak or spill so the contaminant source is known. In other cases, such as a contaminant detected in a drinking water well, investigation is needed to determine the source. In all cases, any available information regarding the volume of chemical(s) that were released into the environment as well as the timing and duration of the release are helpful for understanding the potential environmental impacts.

If the contaminant source is unknown, an evaluation of available information on the chemicals detected and their common sources, nearby uses of those chemicals, and other relevant facts is necessary to determine the source(s) of the contamination. Sometimes, significant investigation, including environmental testing and interviews with property owners and nearby residents, is required to identify the source of a contaminated site.

Once the source is identified, immediate action must be taken to control or eliminate ongoing contamination, if possible, because cleanup is ineffective if there is an ongoing source. If an unlined pond is leaking and contaminating groundwater, it should be taken out of service or a liner system installed to stop the leakage (see Fig. 15.3). However, some sources cannot be immediately stopped. Leaching from an unlined landfill will continue to cause groundwater contamination unless all the buried waste is removed and placed in a lined landfill, or an impervious cover is built on top of the landfill to prevent infiltration of rainwater.

Fig. 15.3

Contaminated site – pond with liner

5.3.2 Site Understanding

Once the source is identified, the site investigation is focused on determining the scope of the contamination. In order to evaluate potential impacts to human health and the environment from the contaminated site, the setting must be understood. The site setting includes the built and natural environment where the contamination occurred and where the contamination could migrate. The natural environment includes the land (surface soils and subsurface geologic formations), water (streams, lakes, and groundwater), and air. In addition to investigating impacts to the natural environment, including the flora and fauna inhabiting that environment, impacts to the human environment and human health must be investigated. The human environment includes places where people live and work, sources of drinking water, and places where people recreate. Particular attention must be paid to places where children could be exposed to contaminants because they are more susceptible to health impacts.

If contaminants were released on the land, an understanding of the local geology will reveal how contaminants might infiltrate vertically into different geologic layers and in which direction contaminated groundwater would flow within a water-bearing geologic layer or aquifer. If subsurface soils consist mostly of coarse sand or gravel, contaminated groundwater can move freely and quickly in the subsurface. However, if subsurface soils are mostly tight clays, groundwater movement will be restricted. There are a wide range of geologic conditions that can be present, and they can vary considerably with depth. Groundwater typically flows into nearby surface waters so groundwater contamination can also cause surface water contamination. Contaminants released onto the ground surface could also be washed into nearby surface waters even if they don’t migrate through groundwater to surface water. If contaminants were released directly into a waterway, the investigation will need to consider flow to other downstream waterways.

In addition to understanding the site setting, the nature of the chemicals that were released must be understood to evaluate their movement and transformation in the environment. Some chemicals readily volatilize and can cause airborne contamination. These vapors are of greatest concern if they enter enclosed spaces such as homes and other buildings. Some contaminants do not volatilize but migrate readily in water, so they can be transported long distances in groundwater or surface water. Yet other contaminants are relatively immobile and tend to stick to soils. Many chemicals will degrade in the environment into other chemicals; sometimes the degradation products are less toxic, and sometimes they are more toxic.

The current uses of the site by humans must be understood in order to evaluate the potential harm to human health. People could be directly exposed to chemicals in surface soil. For example, if contaminated soil is present in someone’s yard, their children could accidentally ingest soil when they are playing outside. If someone is gardening in contaminated soil, they could absorb contaminants through their skin, or contaminants could be present in the produce. If construction workers are digging in contaminated soil, they can inhale dust containing contaminants. If contaminated soil is present beneath a house, vapors from that contamination could seep into the basement or other lower levels of the house. If contaminated groundwater or surface water is used for drinking or other purposes, people can be exposed to contaminants.

The variety of information needed to understand the site illustrates the interdisciplinary nature of contaminated site investigations. Hydrogeologists are critical to the investigation of sites with subsurface contamination because of their expertise in understanding subsurface geology and the movement of groundwater in the subsurface. If surface water is impacted, a biologist provides expertise in evaluating impacts to fish and other aquatic biota. A risk assessor is a scientist with expertise in calculating risks to human health from various contaminants and exposure scenarios. A chemist can provide expertise in the ways that chemicals are degraded and transformed under different conditions. In particular, a geochemist provides specialized expertise in the behavior of chemicals in the subsurface geology. With a focus on solving complex problems, engineers often investigate contaminated sites on their own or as part of a team of specialists. Engineers also may serve as project managers for multi-disciplinary teams.

5.3.3 Site Investigation

Once the source has been determined and the site is better understood, a plan is developed to define the areal and vertical extent of contamination in soil, groundwater, surface water, and/or air. Samples of potentially impacted media will be collected and sent to a laboratory to be tested for a list of chemicals that are associated with the source of the contamination. Because contamination is often present in the subsurface, site investigations often involve drilling borings to collect underlying soil and groundwater samples. Monitoring wells are often installed to test groundwater and determine groundwater flow direction. Triangulation of groundwater elevations surveyed in a minimum of three monitoring wells is required to determine groundwater flow direction. However, site investigations can require the installation and testing of many monitoring wells in multiple geologic layers (see Fig. 15.4).

Fig. 15.4

Contaminated site with monitoring wells

If the contaminant source is a fuel or solvent, it may be present in the subsurface as a pure product rather than as residual chemical concentrations dissolved in groundwater or attached to soil. During the investigation phase, this “free product” may be observed in monitoring wells and/or soil samples. Free product can be lighter than water and float on groundwater, or it can be heavier than water and sink through groundwater. Contamination with free product typically occurs when the source is a fuel or solvent that has spilled or leaked from a tank, drum, or pond. The pure fuel or solvent migrates through the unsaturated surface soils and settles on top of the groundwater or, if it is heavier than water, migrates vertically through groundwater until it settles on an underlying geologic layer with limited permeability. Wherever the free product settles, it acts as a continual source by leaching contaminants into groundwater. During the investigation phase, it is critical to define the extent of free product in the subsurface environment.

A simple site investigation can be completed in a matter of days, while extensive investigations of complex contaminated sites can require years of effort. Complex site investigations are often conducted in phases with each phase providing information that guides the next phase of investigation.

5.4 Cleanup

After the site investigation is complete, the areal and vertical extent of contamination in groundwater, surface water, soil, and/or air is known. The next step is to evaluate whether the contaminants could cause harm to human health or the environment now or in the future. This evaluation must consider the current and future site uses. For example, acceptable chemical concentrations at residential sites are lower because the potential human health risk is higher. People generally spend more time in their homes, and more vulnerable people, such as children and the elderly, are exposed to chemicals in homes. Acceptable chemical concentrations at industrial or commercial sites are higher because people generally spend less time at these sites, and only working-age adults are exposed to chemicals at these sites. If all chemical concentrations are found to be safe for current and future site uses, cleanup is not required. However, if chemical concentrations could cause harm to human health or the environment now or in the future, corrective action (remediation) is needed.

It may not be technologically feasible or cost-effective to clean up the contamination. In these cases, action must be taken to prevent contact with the contaminated media. For example, contaminated surface soil could be paved over and the site used as a parking lot. If people at a residence were drinking contaminated well water, their well can be closed and their home connected to a municipal water supply that comes from another source. In some cases, a deed restriction or other legal document can be used to prevent future use of contaminated groundwater for drinking or future residential development of a site even if the property is sold.

If contamination can be cleaned up, there are many technologies to consider. The following paragraphs summarize commonly used cleanup technologies for soil and groundwater.

5.4.1 Soil Cleanup

Most of the risks associated with contaminated soil are usually related to direct contact with the contaminated soil, contaminants in the soil leaching into underlying groundwater, or vapors from volatile contaminants in the soil entering buildings. Soil cleanup technologies must reduce or eliminate these risks.

One of the most common corrective actions is the excavation of contaminated soil and disposal in a lined and permitted landfill to contain the contaminants. When full, the landfill will be covered to prevent direct contact with contaminants and to minimize exposure of the contaminated soil to rainwater that could cause contaminants to leach into groundwater. The liner minimizes the risk of leachate reaching groundwater, while the landfill is being filled as well as after it is full. Access to permitted landfills is restricted by fencing, and the landfills are monitored and maintained in perpetuity to prevent the release of contaminants to the environment in the future.

In some cases, contaminated soils can be left in place if they are not impacting groundwater and are covered with a cap that prevents direct contact with the soils and minimizes the potential for leaching to groundwater. The cap typically consists of low permeability clay and/or an impermeable synthetic liner that is typically constructed of high-density polyethylene (HDPE). Access to the capped soils must be restricted by fencing and deed restrictions. Long-term monitoring and maintenance are also required.

Some contaminated soils can be treated in situ by mixing with materials that solidify and/or stabilize the contaminants in place. These admixtures often include cement, lime kiln dust, fly ash, bentonite, and/or grout although a wide range of admixtures can be considered to react with a variety of contaminants. Solidification/stabilization typically works best with soils that are contaminated with heavy metals although use of this technology to treat a wide range of contaminants is expanding. Treatability testing is required in advance to determine the specific admixture formula that will be effective on the specific contaminated soils present at a site. In order to treat contaminated soils in situ, an auger is used to bore holes at regular intervals throughout the contaminated area and mix the stabilization/solidification admixture into the soils. Treated soils can be left in place without a cap because they are stable and will not leach contaminants to groundwater at concentrations of concern.

Some organic contaminants can biodegrade under favorable conditions into less toxic or benign chemicals. Some organics biodegrade best under aerobic conditions (oxygen is present), while others biodegrade best under anaerobic conditions (little to no oxygen is present). Some soils contaminated with organic contaminants can be excavated and treated by landfarming to accelerate natural aerobic biodegradation of the organic soil contaminants. Another option for treating soils contaminated with organic contaminants may be thermal treatment with or without incineration. The contaminated soils are excavated and thermally treated to remove or destroy the contaminants. Soil testing is required following landfarming, thermal treatment, or incineration to confirm that organic contaminants have been removed or reduced to acceptable levels. The treated soils can then be placed back in the excavation, and no further controls are required to limit direct contact with the soils or to reduce leaching to groundwater. These types of soil remediation technologies are often used to treat soils contaminated with petroleum products or solvents.

Soils contaminated with organics may also have significant levels of organic vapors present within the soil matrix. These organic vapors pose a threat as they rise to the surface where they can accumulate in overlying structures or be released to the atmosphere where nearby people or animals can be exposed. Organic vapors can be removed from the unsaturated soils above the groundwater table by applying a vacuum to the in situ soils or by introducing air to the soils through sparging or venting. The extracted organic vapors often require treatment before they can be safely vented to the atmosphere. It may take months or years before testing confirms that these vapor removal technologies have reduced organic vapors in contaminated soils to acceptable levels.

5.4.2 Groundwater Cleanup

When groundwater has become contaminated, it is very hard to restore it to natural background concentrations because the groundwater is present underground within the small pore spaces of the soils and rock. The only way to access this subsurface contaminated groundwater is through wells that are drilled vertically or horizontally into the contaminated groundwater or by installing trenches either into the contaminated groundwater or downgradient of the plume at a location that will intercept the groundwater flowing in that direction. Groundwater remediation technologies typically consist of pumping out contaminated groundwater (see Fig. 15.5), treating it in situ, or monitoring natural biodegradation already occurring in the subsurface.

Fig. 15.5

Contaminated site with groundwater remediation

The characteristics of the geologic environment often complicate cleanup. For example, fractured bedrock is a rock matrix that has many fractures running in variable and often poorly understood directions. The groundwater will flow predominantly in these fractures so the direction and magnitude of groundwater flow may not be easily predicted. Even if groundwater is present in a highly transmissive, uniform sand or gravel matrix with a known flow direction, it is not possible to quickly pump all of the contaminated groundwater out of the subsurface. Only a portion of the contaminated groundwater flows from the soil matrix into a pumping well. Continued pumping through a network of recovery wells over a period of years is required to remove the contaminated groundwater and allow clean groundwater to flow into the area. If the soil matrix is a low permeability clay or other matrix that holds the groundwater more tightly than sands or gravels, it is even harder to pump out the contaminated groundwater. Continuous pumping over a period of many years is often required to remove enough contaminated groundwater to reduce concentrations to safe levels. All of the extracted groundwater must be treated to remove the contaminants and the treated water either discharged to surface water or returned to the groundwater to accelerate flushing of contaminated groundwater toward the pumping wells.

In addition to the complications posed by the geologic matrix that holds the groundwater, the contaminants themselves may not be amenable to cleanup. Many contaminants are quite stable in the subsurface, while others are naturally biodegradable under the right conditions. Groundwater contaminants such as heavy metals do not biodegrade at all although they may be attenuated under the right conditions. Attenuation could occur by sorption to soils, precipitation in the groundwater, or transformation into other compounds less likely to migrate. It is important to understand the contaminants present and the subsurface conditions (aerobic, anaerobic, pH, etc.). It may be possible to inject chemicals into the groundwater to create the right subsurface conditions to transform contaminants so they are less mobile. Alternatively, pumping groundwater to the surface for treatment is often necessary to prevent migration. In some cases, a trench can be installed in front of the groundwater plume so the contaminated groundwater flows into the trench. The trench can be filled with chemicals to treat the contaminated groundwater as it flows through the trench or to create the right conditions for natural degradation or attenuation to occur. Contaminated groundwater can also be pumped out of recovery trenches.

If a groundwater contaminant is biodegradable, remediation efforts will focus on providing the right conditions for that degradation to occur. A common example is cleanup of contamination resulting from leaking fuel tanks at gas stations. Benzene, toluene, ethyl benzene, and xylene (BTEX) are volatile organic contaminants that are biodegradable under aerobic conditions. As long as the BTEX concentrations are not so high that they overwhelm the naturally occurring bacteria, biodegradation often occurs at these sites. Groundwater monitoring can be conducted to check for evidence of natural biodegradation. If it is occurring at an acceptable rate and there are no risks to humans or the environment, it may be possible to continue to monitor the site over time to confirm that degradation continues to occur naturally. However, if free product is present or if BTEX levels are too high, the bacteria may not be able to effectively biodegrade the contaminants. In this case, there are chemicals that can be injected into the groundwater to enhance the natural biodegradation, or the contaminated groundwater and free product can be pumped out until the subsurface conditions are suitable for the natural bacteria to effectively biodegrade the contaminants.

5.5 Redevelopment

For most contaminated sites, the goal is to restore the site such that it can be reused. Suitable site uses are determined during the investigation phase, and the level of cleanup that is conducted must support the planned site reuse. Many sites may be cleaned up and their existing use maintained. For example, there is ongoing groundwater cleanup at many gas stations, while the site continues to operate as a gas station. Other sites may be abandoned industrial sites that are not being used at the time the investigation and cleanup occur. In this case, the goal would be to clean up the site so it can be restored to productive use. If some contaminants remain onsite, commercial or industrial use could be appropriate as long as contact with residual contamination is limited. If the site has been completely remediated, residential use might be appropriate. Some sites can be cleaned up such that the site can be used as green space. Because contaminated sites are so common in the USA, redevelopment following cleanup – or during cleanup – is common. Municipalities may own contaminated sites and seek developers who will redevelop sites consistent with site use limitations. Developers may not initially be interested in these abandoned or underutilized sites because of the perception of contamination. The federal Brownfields program provides grants for communities to investigate sites and determine whether they actually require cleanup before redevelopment.

5.6 Community Involvement

Contaminated sites are often present near neighborhoods. People living near, or on, a contaminated site need information to understand the contamination and the risks to them. It is frightening to think you may not be able to see, smell, or taste contamination in your drinking water or on your property, yet it could be impacting your health and the health of your family. Engineers and scientists investigating and cleaning up contaminated sites must consider not only how to protect people who may be exposed to contaminants but also how to clearly communicate the facts to them. Especially when evaluating cleanup options, the input of the impacted community must be considered and is often required by state and federal agencies. Not only will residents be concerned about potential health impacts, they will also be concerned about the impact to their property values and to their community. For example, it may be technologically sound to put a cap over contaminated soils and leave them in place with proper monitoring to be sure there are no future impacts to groundwater. However, people living in the area may not want to live near a repository of contaminated soils. They may prefer the more expensive option of digging up the contaminated soil and hauling it offsite to a secure landfill.

Presenting complex scientific information to people without a technical background can be difficult. It is important not to unconsciously bias the information that is presented or else the community members will not trust the message. For example, providing a professional opinion that a contaminant concentration is “low” is not as effective as providing the actual concentration and the relevant government standard, so community members have proof that a concentration is low. All questions should be answered with openness and honesty. If community members feel they can trust the information they are receiving, it will reduce their stress about the situation.

A common problem when providing information to community members about contaminated sites is the communication of relative risk. Scientists and engineers are often hesitant to state that a contaminated site is “safe” because the level at which there is no health risk associated with a contaminant may not be scientifically proven. The risk from contaminants is typically stated in terms of the estimated incidence of excess cancer cases or other diseases caused by contaminants. An excess cancer risk of one case in a million people exposed is considered an acceptable risk but is not necessarily “safe” because it is still possible for someone to get cancer. Because of this discomfort with saying a site is “safe,” a common tactic used to communicate risk at a contaminated site is to compare the risk to some other situation that is common. For example, the risk at a contaminated site may be compared to the risk of dying in a car accident. However, this is not an appropriate way to communicate risk because people can choose whether to drive a car, but a person does not choose to drink contaminated groundwater. It is better to provide facts about the potential risks from site contaminants and the ways to reduce or eliminate those risks.

5.7 Environmental Justice

According to the EPA [18]:

Environmental justice is the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income, with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. This goal will be achieved when everyone enjoys:

• The same degree of protection from environmental and health hazards, and.

• Equal access to the decision-making process to have a healthy environment in which to live, learn, and work.

Low-income and minority residents are more likely to live near industrial facilities, landfills, and other sites that often cause contamination to the air, land, and water. For this reason, particular attention must be paid to these disproportionately impacted populations when investigating and cleaning up contaminated sites. Potential health and financial impacts to nearby residents must be studied and understood. Local residents must have the opportunity for meaningful involvement in decision-making. Complicated technical information should be provided by trusted advisors in a way that is understandable to non-technical people. If appropriate, information should be provided in multiple languages. Open, accessible, and regular communication will help people understand the site investigation and cleanup process and also facilitate their involvement in the decision-making process. The Woolfolk Chemical Works Superfund Site case history (Sect. 15.7) provides an example of the investigation and remediation of a complex Superfund site and also illustrates the importance of addressing environmental justice issues.

6 Conclusion

Although there have been many technological advances in the investigation and cleanup of contaminated sites since the Love Canal site raised public awareness in the 1970s, there are still new chemicals and products being created that are causing new contamination issues. Once a site is contaminated, it is still very difficult, expensive, and sometimes impossible to restore it to its previously uncontaminated condition. Although continued technical advances are needed to improve the investigation and cleanup of contaminated sites, more emphasis is needed on predicting the future environmental impact of current innovations to prevent the continued creation of new contaminated sites. Our water, land, and air are precious resources necessary to sustain life. As we continue to contaminate them, we are threatening human existence on Earth.

7 Case History – Woolfolk Chemical Works Superfund Site

7.1 Background

The City of Fort Valley, approximately 100 miles south of Atlanta, is the county seat of Peach County. Fort Valley’s population of approximately 9900 is 75% Black and 22% White [7, 31]. Known as the Peach Capital of the World, Fort Valley is Georgia’s largest peach-producing area [20]. Fort Valley is a small, economically disadvantaged community where many of the residents are unemployed and live below the poverty level [19].

The J.W. Woolfolk Company began producing and packaging pesticides on 18 acres of land in 1910 only two blocks from the Fort Valley downtown district and in the middle of a residential neighborhood (Fig. 15.6). It was not uncommon at that time to locate factories close to worker housing; the hazards of pesticides to human health were not well known. During World War II, arsenic trichloride was reportedly produced at the facility for the War Production Board. Production expanded during the 1950s to include formulation of organic pesticides. Eventually, the facility formulated a broad range of pesticides in liquid, dust, and granular forms for the agricultural, lawn, and garden markets [5, 6, 8]. Formulation and/or packaging of pesticides, herbicides, and insecticides (including arsenic and lead-based products) at the Woolfolk Chemical Works, Inc. facility continued through 1999 under several different owners. The material handling methods over the years caused extensive contamination not only on the Woolfolk Chemical Works Site but in the surrounding residential and commercial areas [13, 16].

Fig. 15.6

The facility was used for almost 90 years for formulating and/or packaging pesticides, herbicides, and insecticides

The earliest documented complaint associated with the site occurred in 1966 when a State of Georgia water quality inspector investigated reports from local citizens that the facility discharged waste products to a ditch which flowed into a nearby creek [16]. State records indicate numerous instances where untreated industrial waste was discharged into surface waters. During a routine inspection in 1979, EPA discovered that the facility was discharging untreated pesticide production wastewater into an onsite storm sewer. This unauthorized wastewater discharge flowed into an open ditch south of the facility and then into a creek [8]. It was not until the early 1980s that complaints to the Georgia Environmental Protection Division (EPD) resulted in investigation and cleanup actions [13]. In 1985 and 1986, the Georgia EPD detected metals and pesticides; including lead, arsenic, chlordane, DDT, lindane, and toxaphene; in onsite soil and groundwater as well as in the open ditch south of the plant [8].

7.2 Interim Remediation

Canadyne-Georgia Corporation (CGC) purchased the Woolfolk Chemical Works facility in 1972 and was the owner when contamination was discovered. In 1986, they began investigating and conducting cleanup at the site in consultation with the Georgia EPD [3, 13]. CGC voluntarily cleaned up some onsite contaminated soils and demolished an onsite building contaminated with arsenic. Soils that were considered to be hazardous waste because of high arsenic and lead concentrations were taken offsite for disposal at a permitted hazardous waste landfill. Other soils with lower concentrations of arsenic and lead were disposed onsite in a one-acre area along with some demolition debris and non-hazardous lime-sulfur sludges remaining from onsite activities. These wastes were covered with two feet of low permeability clay and a 30-mil HDPE cap (Fig. 15.7). Although no liner was placed under the wastes before disposal, the cap was designed to minimize rainwater infiltration into the buried wastes so contaminants would be unlikely to leach to groundwater present approximately 10 to 20 feet below [5, 6, 13, 16].

Fig. 15.7

Wastes in this one-acre onsite capped area used for disposal of interim cleanup wastes were later excavated and treated before being placed in an onsite lined disposal cell or disposed of offsite

7.3 Superfund Designation

At the same time that CGC was voluntarily conducting remediation in consultation with the Georgia EPD, the EPA began investigating the Woolfolk Chemical Works Site. In 1990, EPA formally placed the site on the Superfund program’s NPL because of contaminated groundwater and soils resulting from facility operations [16]. Although the majority of the contamination occurred prior to their purchase of the facility, CGC was legally liable for the cleanup and was the primary PRP that actively investigated and conducted cleanup at the site [3, 16].

7.4 Initial Superfund Investigations

Under EPA direction and oversight, CGC conducted investigations in 1991 and 1992 to evaluate the extent of contamination in soil, groundwater, surface water, sediments, and air [5, 6]. The results showed contamination was present well beyond the 18 acres of the Woolfolk Chemical Works Site. The designated Superfund site was eventually determined to cover an area of 31 acres and groundwater contamination migrated over a mile beyond the Superfund site boundaries. Although the initial cleanup focused on soils with high levels of arsenic and lead, additional contaminants were identified including a variety of pesticides and semi-volatile organic contaminants. As investigations continued, it was found that not only were the soils at the production facility contaminated, but the yards of surrounding residences and commercial properties also were contaminated. Further investigation revealed that airborne dust containing arsenic at unsafe levels had entered people’s homes. Although groundwater was contaminated, it was not a source of drinking water, and the City of Fort Valley municipal water supply wells were not contaminated by the Woolfolk Site (Fig. 15.8).

Fig. 15.8

The author sampling waste byproducts remaining onsite

7.5 Legal Issues

At the same time that CGC was beginning additional site cleanup under the Superfund program, they were sued by over 600 Fort Valley residents who were negatively impacted by the Superfund site (Fig. 15.9). The 1993 class action lawsuit was reportedly settled for $11,000,000 after several years of litigation [25, 28, 30]. CGC continued to investigate and remediate site contamination, while the lawsuit was ongoing although interactions with the community members were complicated by the active litigation. In addition to the cost of the litigation and settlement, CGC estimated the cost for the Superfund work at approximately $50,000,000 [30]. It became more difficult for CGC to pay these high costs, and in 1998 the EPA took over the investigation and cleanup activities at the site using federal funds [16]. Ultimately, CGC’s parent company paid EPA $5,000,000 in 2005 to settle further claims with the US government. Eventually CGC’s parent company filed for Chap. 11 bankruptcy protection in 2014 [29].

Fig. 15.9

The Woolfolk Chemical Works Superfund Site located in the middle of Fort Valley, Georgia, had a negative impact on the community

7.6 Contaminated Soils and House Dust

In 1993, EPA required CGC to clean up residential properties to eliminate the immediate threat to public health from contaminated soil on residential properties [9]. CGC purchased some properties and permanently relocated the residents, while other residents were temporarily relocated so that contaminated soil could be excavated from their property and arsenic-laden dust removed from their homes. During 1994 and 1995, approximately 23,000 tons of contaminated soil and debris were removed from 43 properties and five road shoulder areas and rights-of-way. An onsite wooden building was demolished because the wood was contaminated with dioxin (Fig. 15.10). EPA also required removal of sediment and soil from the stormwater ditch that drained the site [5, 6, 13].

Fig. 15.10

Some of the buildings were in poor condition and required demolition. Special handling during demolition and disposal was required for some buildings with contaminated building materials

In 1994 and 1997, the living spaces of residential houses with arsenic-contaminated house dust were cleaned by CGC using high-efficiency vacuum cleaners with special filters [2]. Following the initial cleaning, CGC retested homes to confirm that the cleanup had met EPA criteria [4]. EPA conducted additional testing in 2002 that found more arsenic contamination in residential yards and attic dust. In 2008, EPA excavated additional contaminated soil from residential properties, cleaned 63 attics that had dust-containing elevated levels of arsenic, and decontaminated a drainage pipe [13].

The contaminated soils that had been consolidated in a capped area onsite before the Woolfolk Site was listed on the NPL were investigated in 1996. It was found that the volume and depth of contaminated soils were significantly greater than originally estimated. It was determined that arsenic-contaminated soils could be treated onsite by solidification and stabilization to minimize contaminant leaching. If the solidified soils passed leaching tests, they could be disposed of onsite in new HDPE-lined containment cells to further limit the potential for contaminants to leach to groundwater [5, 6, 13].

In 1998, EPA required that CGC excavate the contaminated soils from the capped area and dispose of them offsite. However, CGC claimed they did not have sufficient funds to conduct this work because of the large volume of soils to be removed. They believed EPA’s estimate of 8000 cubic yards of soil requiring excavation from the capped area was much lower than the actual volume. EPA conducted additional investigations and increased their estimate of the volume of contaminated soil to 120,000 cubic yards. Based on this higher estimated volume, EPA determined that the contaminated soils would be treated by solidification and stabilization before placing them in HDPE-lined containment cells to be constructed onsite [11].

Because of CGC’s financial difficulties, the cleanup of the onsite capped area was conducted by EPA using federal funds. During the cleanup activities, the actual volume of contaminated soil was found to be even higher than EPA’s second estimate. Between 2006 and 2010, approximately 500,000 cubic yards of contaminated soil were excavated to an average depth of 35 feet [10]. Batches of arsenic-contaminated soils were treated by solidification and stabilization using Portland cement, lime kiln dust, and ferric or ferrous granules or powder. A sample of each batch was tested by the Toxicity Characteristic Leaching Procedure (TCLP) to evaluate whether arsenic and other contaminants would leach from the treated soils. Those soils that passed the leaching test were placed in three HDPE-lined areas constructed onsite. Because the actual volume of contaminated soils found during the cleanup was significantly greater than originally estimated, there was not enough capacity in the onsite HDPE-lined containment areas. Once these onsite lined areas were full, treated soils that passed the leaching test were disposed of offsite in a municipal landfill. Treated soils that did not meet treatment standards were disposed of offsite in a hazardous waste landfill. After they had been filled, the lined containment cells were paved [13] (Fig. 15.10).

7.7 Groundwater

In 1994, EPA required that CGC remediate groundwater contaminated with arsenic and organic contaminants. Following treatability testing and design, CGC constructed a groundwater pump and treat system and began operating it in 1998. Contaminated groundwater was pumped from 24 wells to the surface, treated by precipitation, filtration, and activated carbon adsorption before being discharged to the Fort Valley municipal wastewater treatment system for further treatment prior to discharge [3]. In 2002, the groundwater pump and treat system was shut down by CGC due to inadequate performance but restarted in 2008 by EPA. The system was again shut down in 2014 because it appeared that the groundwater plume was continuing to migrate even while the system was in service. Contaminated groundwater was found more than 2.5 miles downgradient of the Woolfolk Site despite operation of the groundwater pump and treat system for more than 15 years.

From 2008 to 2019, various private wells and monitoring wells were tested, and pesticides were detected in residential and irrigation wells downgradient of the Woolfolk Site. Groundwater beneath the Woolfolk Site also still contained high levels of arsenic and other contaminants. Higher pesticide concentrations found in private wells downgradient of the site could be due to a source of groundwater contamination other than the Woolfolk Site or pesticide contamination from the Woolfolk Site that was found in the drainage ditch leading to an offsite stream [13]. EPA continues to investigate the source of this groundwater contamination.

7.8 Redevelopment

During initial cleanup activities, CGC purchased and cleaned up 13 properties under EPA oversight. Deed restrictions for these properties were required to prevent residential development and the use of underlying groundwater. Following cleanup, CGC transferred the properties to the City of Fort Valley and contributed funds to support redevelopment [13]. In 2002, an EPA Brownfields pilot grant provided to the city from the Superfund Redevelopment Initiative was used for reuse planning. The city conducted a redevelopment study and sought input from local residents on potential redevelopment ideas. After extensive discussions, the community decided to build a library and literacy center on some of the remediated properties. Another property containing the Troutman House, a once-contaminated antebellum farmhouse, was converted into a Welcome Center and office space for the Fort Valley Chamber of Commerce (Fig. 15.11). Another former residence nearby was redeveloped as an adult education center. Residences and other private properties that were impacted by contamination were cleaned up and remain in use. In recognition of their proactive engagement and support of reuse, EPA presented the City of Fort Valley with an Excellence in Site Reuse Award in 2009 [12].

Fig. 15.11

Following cleanup, properties like this one have been returned to productive use. The Troutman House is now a welcome center that also provides office space for the Fort Valley Chamber of Commerce

Much of the former Woolfolk Chemical Works site where contaminated soils were excavated, treated, and disposed in lined cells has been paved and is now being used by recreational vehicles and for school bus parking. Other areas of the site that were remediated and revegetated are used for an event space called the Fort Valley Festival Park that opened in 2012. The Fort Valley Public Works Department also built a community playground and veterans memorial on the remediated site in 2013 [17, 23].

7.9 Community Involvement

During the early days of the Woolfolk Superfund process, the community mistrusted the regulatory agencies and CGC. This distrust manifested itself in the perception that the entire city was contaminated and the health of Fort Valley’s residents was compromised. Members of the Black community formed the Woolfolk Citizens Response Group (WCRG) to address issues related to the Woolfolk Site and potential threats to the health of the community [19].

Fort Valley residents needed a way to voice their concerns and receive progress reports from EPA, other federal and state agencies, and technical experts. The Woolfolk Alliance was established in 1998 to provide a forum to discuss and reach consensus on cleanup issues at the Woolfolk Site. Woolfolk Alliance members included representatives of the local, county, and federal government; the WCRG; local businesses; any private citizens that wanted to attend; and CGC. The initial meetings, led by an outside facilitator, were tense because there was a great deal of anger, frustration, and mistrust among the citizens, the government agencies, and CGC. After the difficulty of the first few meetings, the group asked the Mayor of Fort Valley to preside. From that point on, Mayor John Stumbo effectively led the group and was able to quiet the anger, encouraging attendees to ask questions and make comments in a respectful way. He personally paid for homemade lunches for the group during each meeting because he felt that if the attendees could eat together, they would get better acquainted and talk about their families, and a community would be formed [26, 27]. At each of the Woolfolk Alliance meetings, technical presentations were made to explain ongoing investigation and cleanup activities to the group and solicit their input. Members of the Woolfolk Alliance met regularly in Fort Valley for more than 20 years [19].

In 2010, EPA awarded the Woolfolk Alliance the National Community Involvement Award for outstanding achievements in the field of environmental protection and for its dedication and commitment to the cleanup and redevelopment of the Woolfolk Site. In 2011, EPA awarded Peach County and Houston County public health representatives to the Woolfolk Alliance the Notable Achievement Award for demonstrating a sustained and thorough understanding of environmental justice concerns and assisting in providing opportunities for the community to play a meaningful role in the environmental decision-making process [16].