E-mail your tasks to: hughscot@isu.edu
On Staten Island, New York, a mountain is growing, but no natural geological processes are involved. This mountain is entirely manmade. Each day 11,000 tons of municipal and corporate waste are disposed of at the Fresh Kills Landfill on the island. The facility spans 3,000 acres, and by the year 2005 the mountain of trash is expected to reach 150 to 200m above sea level!
The problem of waste, and what to do with it has begun to reach crisis proportions. At least half of the cities in the United States are running out of landfill space. Costs of treatment and disposal are skyrocketing, yet more and more waste is generated each year. Resources are depleted, human health problems are growing, and widespread environmental damage is occurring. Nor is this situation limited to the United States - our global environment is being filled with garbage and toxins at an ever increasing rate.
As the magnitude of the problem grows apparent the search for safer methods of waste management and disposal has begun. This search is exemplified by the paradigm shift occurring in the field of Waste Management.
Initially the idea of: "OUT OF SITE, OUT OF MIND" - (philosophy 1) was most prevalent. This philosophy has resulted in widespread environmental damage. Unfortunately the philosophy persists, and continues to pose serious problems.
For example, many people dispose of waste oil from their automobiles by pouring it down the drain or throwing it away. Once it is gone they forget all about it.
Two waste management approaches evolved from the "out of site, out of mind" philosophy. The first of these is the principle of:
"The dilution solution to pollution" (philosophy 2)
This is extremely environmentally intensive, and is no longer a suitable method for waste disposal as many environments have already reached their maximum compensation points.
The second method is: "CONCENTRATE & CONTAIN" (philosophy 3) This method is the most popular today. These types of processes are very energy intensive as well as expensive.
Most recently the idea of: INTEGRATED WASTE MANAGEMENT (IWM) (philosophy 4) is emerging. This philosophy addresses all aspects of waste management from minimizing the initial production of waste through resource recovery. It is largely based on the belief that wastes are resources out of place. This new perspective is having a big impact on all aspects of waste management. Technological advances are being made to increase the efficiency of manufacturing processes, thereby minimizing waste generation; resource recovery through reuse and recycling is on the rise, as is sequential land use; and innovative, alternative methods of waste treatment are being developed.
For example, the field of Industrial Ecology has evolved from IWM. Industrial Ecology involves the cataloging of wastes from a particular industry and then selling these wastes to another industry that uses those materials in their processes. Another example of IWM occurs in Mountain View, California where the beautiful Shoreline Amphitheater was constructed on top of a closed urban landfill. Federal and State agencies are also working to promote IWM practices.
As an example visit: EPA's Office of Solid Waste Web Site
Also take a look at: Idaho DEQ's web site
Briefly describe one illustrative example for each of the four waste management philosophies discussed above.
copyright: National Geographic (Vol. 186, No. 1)
Unfortunately, while big steps are being taken by industry, much of our country's waste problem results from the tremendous amount of trash thrown away by the average American family. All sorts of wastes (hazardous and non-hazardous) are disposed of daily. Urban landfills have become a significant source of toxic pollution, yet individual citizens are exempted from virtually all of the current waste management legislation!
In addition to creating pollution problems, valuable resources are being wasted. A photograph from the National Geographic illustrates the difference between the amount of waste now recycled by the average family of four each year (1,100 pounds - at right) and the amount simply thrown away (5,300 pounds - at left). On average only 17% of the yearly trash generated is recycled. It is possible to do a whole lot better!
The four basics of IWM are:
These are the four primary things everyone can do to help minimize the amount of waste created each year. These techniques allow "at the source" waste management vs. "end-of-pipe" management - something which generally saves money, reduces regulatory requirements and paperwork, and saves raw materials and energy. Reusing and recycling diverts materials from the waste stream and converts them into resources.
A QUICK FACT: ONE THIRD of all waste in the United States is packaging!
Where does your trash go ? ? ?
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Each year Americans throw away about:
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It only takes an average of two minutes a day to recycle glass, tin cans, aluminum cans, newspaper, mixed waste paper and cardboardEvery ton of glass recycled saves the equivalent of nine gallons of fuel oil.Throwing away an aluminum beverage container wastes as much energy as filling the can half full with gasoline and pouring it out.Each ton of paper recycled saves 17 trees.Simply recovering ONE print run of a Sunday edition of the New York Times would leave 75,000 trees standing.Americans go through 2.5 million plastic bottles every hour, only a small percentage of which are ever recycled! |
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1. Read some facts about plastics recycling at the Environmental Defense Fund website.
2. Visit the Bureau of International Recycling web site and use the links to recycling information to learn more about recycling all kinds of different materials. Find out and list what materials are recyclable in your home town.
3. Go to the Northeast Recycling Council recycling data web site to find out which northeastern state has the highest recycling rate, and what that rate is. (HINT: find the most recent statistics) How does this compare to the national average?
IV. WASTE HISTORY & ENVIRONMENTAL LEGISLATION
WASTE is nothing new. It is old as humanity! Trash from primitive camps and kitchen middens lend valuable information about ancient peoples.
A THOUGHT: What will our trash piles say about us to future generations?
As humans settled into ever growing urban areas, waste became a problem. The first waste law in the U.S. was passed in Georgetown in 1976. This law prohibited people from dumping garbage in the street, and from storing it on their property. The first federal law that mentioned waste was the Rivers & Harbors Act of 1899. This law became known as the "Refuse Act" as it prohibited the disposal of any solid objects (that could cause obstructions) in U.S. waterways. The Army Corps of Engineers has jurisdiction over this law, and it was the forerunner to the NPDES permit system. (The National Pollutant Discharge Elimination System permit that must be obtained prior to discharging pollutants into U.S. waterways.)
In 1965 the Solid Waste Disposal Act was passed - the first legislation specifically regarding waste. This Act was targeted to having state and local agencies as the primary force for waste management, and established the Federal Government as a resource for grants, loans and technical assistance. In 1970 the National Environmental Policy Act was created. This law created an executive level council, the Council on Environmental Quality, to advise the Presidential Office on environmental matters. The law also required that all Federal Agencies must give adequate consideration to environmental impacts in their decision making processes.
In the 1960's and 1970's growing environmental awareness brought to light a whole new problem with waste - severe pollution arising from the disposal of HAZARDOUS WASTES - a product of the Age of Industrialization. People everywhere began to find serious problems in their own backyards.
A number of events occurred which caused public opinion to demand protection from our toxic end products. Two landmark episodes were the publication of Rachel Carson's book "Silent Spring", and Love Canal. Ms. Carson's book discussed the bioaccumulation of DDT (a pesticide). DDT was discovered in the reproductive tissues of numerous species of birds. This chemical causes thinning of eggshells such that when the female attempts to brood her eggs she ends up crushing them. Ms. Carson's work described for the first time how all things are connected, and clearly demonstrated that the Out of Site, Out of Mind philosophy was no longer valid.
The Love Canal incident was the catalyst for the passing of the two most important pieces of waste legislation. The first is the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) or SUPERFUND. Love Canal is located near Niagara Falls, New York. During the 1940s and 1950s indiscriminate dumping of hazardous wastes by companies such as Hooker Chemical Co. occurred. Eventually the site was filled in and sold to the Niagara Falls School District. Although instructed on the nature of the site, and told not to engage in excavation or underground construction, the school district built an elementary school in the area, and a neighborhood of houses grew around it - complete with basements. In the 1970s strange odors could be detected indoors and people began experiencing symptoms of chemically induced illnesses. Investigation by reporter Michael Brown (he won the Pulitzer Prize for this) uncovered the truth and the U.S. government purchased the entire Love Canal site.
Although the danger was never as great as the public perceived it to be, Love Canal was the impetus for the passage of CERCLA in 1980. This legislation was designed to provide funds and technical ability for the clean up of hazardous waste sites contaminated by past generation, transport, and disposal activities. CERCLA aims at finding the Potentially Responsible Parties (PRPs) and making them pay for clean up, however funds exist in case no PRPs can be found. Site selection is done by a simple site assessment, after which a priority number is assigned. If the number is high enough the site is placed on the National Priority List (NPL) and becomes a Superfund site. Once CERCLA got underway, it quickly became apparent that a tremendous amount of Superfund sites existed. There were 100 sites on the NPL by 1988.
CERCLA has a number of limitations. Most of its funds have been soaked up by legal battles attempting to assign liability and responsibility. Also, CERCLA's testing methods may not be stringent enough. Unfortunately this law deals with such huge problems that it is not possible to be rigorous. A number of the CERCLA treatment technologies are in themselves environmentally disruptive. Methods such as excavation and removal of contaminated soil, structures etc. are widely used in order to minimize time and money expenditures. Of course, they then have to face the problem of what to do with the CERCLA material!
CERCLA also makes emergency provisions for responding to current releases of hazardous substances. In 1994, SUPERFUND was extended by the Superfund Amendments and Reauthorization Act (SARA). An important part of SARA is Title III - known as the Emergency Planning and Community Right-to-know Act (EPCRA). Superfund was extended again in 1994 by the Superfund Reform Act.
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Visit the EPA's Superfund Web Site and find the Superfund sites in your state. List the three sites closest to your home, and briefly describe what the main contaminants of concern are |
The second of the two major pieces of waste legislation also stemmed from the Love Canal incident. The RESOURCE CONSERVATION AND RECOVERY ACT (RCRA) passed in 1976 in response to the problem of determining liability and responsibility at Love Canal. The Act was intended to provide a regulatory framework for waste management that would prevent this type of uncertainty in the future. It consists of comprehensive legislation dealing with all aspects of current, ongoing waste production and disposal - particularly of hazardous material. It also assigns "CRADLE-TO-GRAVE" responsibility to generators of hazardous wastes.
RCRA consists of lots of subtitles some of which are:
This was the first time the Federal Government was empowered to regulate hazardous wastes. RCRA was extended by the Hazardous and Solid Waste Amendments (HSWA) in 1984, extended again in 1989, and expanded by the Federal Facilities Compliance Act in 1992.
Other important pieces of waste related legislation are:Review the PDF Document: Waste Regulation Tree
a flowchart that summarizes the structure of the waste regulation "tree". (NOTE: this document is in PDF format. CLICK HERE if you need information on using PDF)V. GENERATION, FATE, & TRANSPORT OF WASTES
Wastes are generated in virtually every process known to modern man. Wastes can be toxic or non-toxic. Although non-toxic solid wastes are a growing problem, hazardous wastes are of much greater concern due to their potential to damage human health and the environment. Most generators of hazardous waste are subject to regulation under such laws as RCRA, CAA and CWA.
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Visit the Idaho Department of Environmental Quality and go to the section concerning industrial hazardous waste (or search your own state or country's Department of Environmental Quality for this information). Then answer the questions below: 1. What are the three categories of waste generators? 2. How many tons of TSD wastes were disposed of in 1996? |
Wastes come in all phases - solids, liquids and gases. The chemical and physical characteristics of the waste, as well as those of the receiving environment will determine what actually happens when the waste enters the environment. Factors such as the combustibility of the waste, its potential to be broken down by microorganisms (biodegradation), or how readily it will volatilize (turn into a gas) are all crucial to determining what the waste will do, where it will go, and if it will cause harm. Pollutant behavior is controlled by both transport and transformation interactions.
In terms of human health and the environment the two major routes of concern are Air and Groundwater:
| TIME | CONDITIONS | PLUME PATTERN |
|
NIGHT |
Ground level air is cooled as heat is lost from earth's surface. This forms an inversion. Pollutants spread out under the inversion and are trapped (they can't go any higher). |
FANNING
|
|
EARLY MORNING |
Ground is heated by the sun and warm air rises in an eddying motion. Eddies bring pollutants to ground level. | FUMIGATION
|
|
MORNING |
Eddies eventually enter the inversion and begin to break it up. | CONING
|
|
EARLY AFTERNOON |
Continued heating may create very large, looping eddies. | LOOPING
|
|
LATE AFTERNOON |
Eddy formation slows and a new inversion builds from the surface upwards. Emissions are carried upwards. This is the ideal time/conditions to emit air pollution as it won't come to ground level. | LOFTING
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(NOTE: this is not on your test!)
AIR POLLUTION occurs as particulate matter, smoke, dust, liquid mists, gases and vapors. These can be broken into some general emissions categories as illustrated by some examples:Many more possibilities exist, but that is the general breakdown.
Once a pollutant enters the atmosphere its transport will be largely controlled by wind speed and direction, and other atmospheric phenomenon such as temperature inversions (which can trap pollutants). The emissions leaving a stack or area or described as a PLUME. A plume can be defined as an area where contaminants are in higher concentrations than background levels.
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Use the "OVERVIEW OF AVAILABLE DATA" link at: EPA's Envirofacts Database to request a TOXIC RELEASE INVENTORY datasheet for your home state (use the "Tri State Reports" Link that you will find). Then answer the following questions:A. What is the reporting date for these figures? B. What was the number one chemical released to the air? In what quantity? C. What was the number one facility for air pollution releases? What was the total amount of pollutants they released? |
Adapted From: LaGrega et al. "Hazardous Waste Management"1994. McGraw-Hill, Inc.
GROUNDWATER POLLUTION is an extremely important problem. As you recall from Module 8, the majority of our drinking water supplies come from underground aquifers. Recall that many of these are SOLE SOURCE aquifers - meaning that they are the ONLY source of fresh drinking water for a given region.
FOR A REVIEW OF GROUNDWATER FLOW VISIT MODULE 7 - PART 2
Due to their importance all kinds of legislation has been enacted in the effort to keep our drinking water supplies from being harmed. The most significant of these has been the Safe Drinking Water Act. Under SDWA the EPA sets standards for all kinds of contaminants that may enter groundwater.
At EPA's list of contaminants, their standards, and their potential impacts.Major categories of groundwater pollution are:
Major sources of groundwater pollution are:
NOTE: A major source of pollution comes from URBAN RUNOFF. Oil, antifreeze, paint, sediment, lead and all kinds of other substances get washed into our sewers with every storm event. This type of pollution is called "Non-point Source" because it is impossible to pinpoint where it comes from. This also makes it impossible to regulate, yet some estimates indicate that up to 80% of water pollution may come from this source! For some great information read "Our Polluted Runoff" in the February, 1996 issue of the National Geographic.
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GO TO THE Center for Environmental Information. Follow the link for County Level Data. Select your state and then your county and then request a drinking water profile. Learn about your aquifer, then answer this question: What year had the greatest number of health violations by the Community Water System providers? |
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A plume |
A plume front |
Just like air emissions, contaminants spreading through the subsurface are called plumes. Plumes will normally lengthen and widen as they move away from the contaminant source.
The length:width ratio is called the ASPECT RATIO. The leading edge of the plume is called the FRONT.
A plume front can generally be defined from a graph which shows contaminant concentrations at different distances from the source. The front is considered to occur at the midpoint between pollution levels of 84% and 16% of the initial source concentration. A front can be used to determine how fast the contamination might be spreading.
Keep in mind that the subsurface environment is highly complex. A multitude of chemical and physical properties, both abiotic and biotic, determine microscale conditions. Upon release into this environment pollutants will interact dynamically with environmental factors in a variety of relationships collectively termed "fate and transport". Migration, partitioning into air, gas or separate liquids, biological destruction and other outcomes are all possibilities. Pollutants generally follow water flow paths through the unsaturated soil matrix (vadose zone) until reaching the water table where some constituents will dissolve into groundwater while the remainder may spread laterally and "float" on the surface of the aquifer, or sink towards the bottom of the aquifer. Eventually, seasonal water table fluctuations can result in a contaminant "smear zone" from the high to low water mark elevations. During transport volatile components may escape into the gas phase. Specific phase distributions depend upon the individual characteristics of the constituent species (such as molecular weight, structure, electronegativity), and those of the receiving environment.
It is critical to the success of a subsurface pollution remedial campaign to fully delineate each parameter affecting fate and transport. Generalizations can be made, but each spill presents a context-specific treatment problem defined by local conditions.
Adapted From: LaGrega et al. "Hazardous Waste Management"1994. McGraw-Hill, Inc.
Review this PDF File: Fate and Transport
For the full range of subsurface pollutant fate & transport pathways (this is not on your test) (NOTE: this document is in PDF format. CLICK HERE if you need information on using PDF)Clearly, the absolute shape of the plume, its direction of spread, and its speed of movement are controlled by interactions among all sorts of diverse influences. Lets look at some examples:
Hydraulic conductivity and hydraulic head data help determine which way the plume will travel and give at least some indication of how fast it will go.
Porosity is also useful for evaluating migration rate. Porosity (amount of empty space) will help indicate how convoluted a path must be followed by molecules in the subsurface. Velocity of subsurface migration depends upon tortuosity of the flow paths as well as contaminant/environment interactions. Interconnected pore channels are frequently so convoluted, or "tortuous", that actual flow speed is generally significantly lower than calculated linear velocity...the more tortuous (winding) the flow path, the slower the pollutants will travel.
Simple aquifer characteristics such as the presence of impenetrable confining layers will also help determine plume shape. Contaminants will usually spread over and around such confining structures - something which may cause them to flow into unexpected areas. This may also occur if there are faults or fractures present that can provide preferential conduits for contaminant migration.
Surface processes that influence groundwater will also have an impact on contaminant fate and transport. Local climate, recharge rate and other processes are significant. (Go back to Module 7 - Part 1 if you need to review some of these concepts.)
There are also numerous mobility, partition and solubility coefficients which can be used to describe how plumes will spread. These are properties of the contaminants themselves. A general equation for describing how a contaminant might distribute itself in the subsurface is:
KD = CA/CB
Where CA and CB are the concentrations of the pollutants in two different phases such as water or solid.As an example consider a pollutant that is highly water soluble. This pollutant will have a large distribution coefficient in favor of the aqueous phase. This coefficient is actually called the Octanol-Water Distribution Coefficient or KOW and describes whether a contaminant is more soluble in water (hydrophilic, low KOW) or in the lipid compound octanol (hydrophobic, high KOW) . A pollutant with a low KOW will generally dissolve in the groundwater and be carried along with it. A plume of this pollutant will also follow the same direction and migrate at the same rate as the groundwater. By contrast pollutants with a high KOW may be absorbed into the organic soil matrix, and will travel much slower. Obviously, to truly understand where a plume will go and how fast it will get there you need to know as much as you can about the chemical and the aquifer it is in.
For a brief discussion of a broad range of factors influencing subsurface pollutant fate & transport pathways!VI. WASTE DISPOSAL METHODS
A variety of waste disposal methods exist. Use the following links to get an overview of:
The selection of a waste disposal method must take account of the chemical and physical properties of the wastes. For example, easily combustible wastes can generally be treated by incineration. Remember though that each method has its pros and cons, and none are 100% efficient. Sometimes the selection of a treatment method involves choosing the least potentially harmful method. We will discuss the following practices:
This is by far the most common disposal method. Drains, sewers, windows, pits and so on are all used to get rid of unwanted substances. Both hazardous and non-hazardous wastes find their way into the environment by this route.
TASK 7 Learn about household hazardous wastes from the EPA and then make a list of the hazardous chemicals in your own home. Select three of those chemicals and state a safe alternative to them (HINT: use the table you will find on the website) |
COMPOSTING
Composting is the decomposition of organic matter by biological organisms. On a household scale composting can significantly reduce the amount of garbage you produce. Composting can also be done on a municipal scale. For example, in 1983 the VAM recycling and waste treatment facility in Wijster, Netherlands produced 125,000 tons of quality compost from discarded municipal organic waste!
HINT: for more information on composting, type "composting" in the URL line of your web browser or do a regular search using your favorite search engine. There is lots of information out there! The Environmental Defense Organization is also a good place to learn more about wastes and what you can do.INCINERATION
Plasma Furnace
Incineration, or "thermal treatment", is the high temperature reduction of wastes via combustion. Incineration can attain a 75-95% reduction in waste mass, and can destroy hazardous pollutants with efficiencies as high as 99.99%! A wide variety of thermal treatments exist. One system that is gaining popularity is the plasma furnace.
These are used to treat hazardous wastes. They operate at incredibly high temperatures (8,000-10,000 degrees Celsius) using gaseous Argon. At these temperatures you atomize everything! Gaseous Argon is injected into the incinerator and then spun by a radio frequency coil until it reaches operating temperatures. A spray of hazardous waste is then injected via a nebulizer tube, and the combustion reaction is allowed to occur. Some drawbacks are that they can only handle small amounts of waste at any one time, and they are time consuming (in terms of operation and maintenance) and expensive. Plasma technology is extremely effective if used correctly.
All kinds of wastes are incinerated. A lot of attention has been given to the disposal of chemical and biological weapons via incineration. As you can imagine, this is a highly controversial issue!
Take a look at some information and good links about the chemical weapons incinerator facility in Toole Utah:
DEEP WELL INJECTION
The underground injection of liquid wastes has been occurring in the United States for many decades. In general, this technique is used to dispose of wastes deep below the earth's surface in well-confined geologic formations. Current legal standards require that deep well injection facilities prove that wastes will not migrate from the injection zone into an actual or potential United States underground source of water (USDW) until the waste has been rendered harmless by natural subsurface processes. Furthermore, this period must be at least 10,000 years. Contingency plans for remediation if such migration does occur must be constructed.
Deep well injection directly introduces liquids into a deep aquifer in the subsurface environment via pressurized wells.
Here is a disposal well schematic:
CLICK ON THE THUMBNAIL TO SEE THE FULL-SIZED DIAGRAM
copyright: Hassan, Syed E. "Geology and Hazardous Waste Management". 1996. Prentice Hall
Disposal wells use high pressures to overcome existing lithologic and hydrostatic forces in deep aquifers, thereby forcing the aquifer to accept waste loads. Typical injection rates range from 100-400 gallons per minute, and average injection pressure is typically 1,000psi. Disposal wells can be anywhere from a few hundred feet deep to over 12,000 feet deep!
Federal regulations recognize 5 types of disposal wells, each with their own particular guidelines:
As of 1993 there were 438 Class I Wells in operation of which 39% were injecting hazardous wastes.
HERE IS A PARTIAL DISTRIBUTION:
|
STATE |
NUMBER OF WELLS |
STATE |
NUMBER OF WELLS |
|
Arkansas |
4 |
Florida |
1 |
|
Illinois |
4 |
Indiana |
4 |
|
Kansas |
5 |
Kentucky |
1 |
|
Louisiana |
29 |
Michigan |
8 |
|
Mississippi |
7 |
Ohio |
2 |
|
Oklahoma |
4 |
Texas |
89 |
|
Wyoming |
14 |
TOTAL |
172 |
From: LaGrega et al. "Hazardous Waste Management"1994. McGraw-Hill, Inc.
Multiple factors must be considered when selecting a disposal well site. Careful determination of how the aquifer will respond to intended injection rates, pressures and type of waste is crucial. The location of confining structures above and below the receiving body must be assessed. Sites must be bounded vertically and laterally by confining strata in order to minimize the possibility of waste migration into USDWs. Site geology must be carefully reviewed to determine if any possibility of hydrologic connection exists between the receiving aquifer and surrounding USDWs. The location of faults, fracture zones, previous patterns of seismicity and other criteria are used to determine this possibility. Also, the location of any old conduits between aquifer layers must be accounted for. Abandoned or improperly closed wells can provide avenues for waste migration. Physical and chemical characterization of the waste is also important in order to determine if the waste and the receiving aquifer will be chemically compatible. Frequently, pretreatment of the waste is required in order to avoid system clogging, corrosion of well casings or other problems.
Aquifers with low pressure head, high transmissivity, and high permeability are preferred. the most common aquifer sites selected are in deep sedimentary rock, usually composed of limestone, dolomite or sandstone. These types of aquifers are frequently located at the edges of continental plates, and contain extremely brackish water.
NOTE: A major problem with deep well injection is that it can cause earthquakes!
READ ABOUT DEEP WELL INJECTION AND INDUCED SEISMICITY
OCEAN DUMPING
READ THIS SECTION IN YOUR TEXT - PP.342-343
SURFACE DISPOSAL
USEFUL DEFINITIONS
Covers are intended to prevent infiltration into the waste disposal site.
With this in mind, why do you think it is beneficial to include living vegetation as part of the cover system?
Covers serve a number of other purposes as well:TYPES OF SURFACE DISPOSAL
Storage surface impoundments are temporary structures. At some point contaminants and soil must be removed and treated elsewhere. Many industrial facilities have temporary surface impoundments such as holding ponds or lagoons.
Disposal surface impoundments are designed so that they can eventually be closed in the same manner that landfills are closed. These structures are designed with the idea of permanent storage in mind. The following EPA requirements apply to both types of surface impoundments:
4. Open Dumps
Open dumps are the oldest, most common method of waste disposal used in the United States. These sites have absolutely no controls on contaminant migration and transport. They are major sources of pollution. The passage of RCRA prohibited this type of disposal facility. RCRA required that all such dumps be closed, and that state-of-the-art sanitary landfills be constructed insteadSANITARY LANDFILLS are areas designed and constructed to contain discarded solid wastes so as to minimize releases of contaminants to the environment. Landfills are intended to be permanent waste disposal sites. They must include covers, liners and leachate collection systems as described above. Sanitary landfills are regulated under Subtitle D of RCRA. All municipal waste disposal facilities are now sanitary landfills.
Although a significant improvement on open dumps, sanitary landfills have their drawbacks. First, they are not designed to handle hazardous wastes such as solvents or pesticides. In fact RCRA contains a "LAND BAN" on the disposal of hazardous wastes in municipal sanitary landfills. Unfortunately, these wastes get into the landfill anyway as a component of household wastes which are not currently regulated. Another problem is that leachate formation does occur and frequently leachate manages to escape from the landfill site. This can cause some serious pollution problems if the landfill is near a drinking water aquifer. Methane gas is also produced by the anaerobic decomposition of organic wastes placed in the landfill. This gas will readily migrate through the subsurface and can make its way into basements and other underground structures. This is a problem due to the ignitability and toxicity characteristics of the gas. In addition to a leachate collection system, sanitary landfills must contain a system for the collection of methane gas.
A DIFFERENT PERSPECTIVE: the methane gas produced in a landfill is a resource out of place. It could be collected and burned to provide the energy required to operate the landfill!
Due to the production of leachate and methane gas, landfill sites must be selected carefully in order to minimize migration of these contaminants should a release occur. It must always be assumed that leachate and methane will be produced and that some of this could escape.
All of the following factors must be considered during the site selection process:
Topographic Relief
Climate (particularly precipitation amounts)
Geology (type of rocks/soils and their properties)
Hydrogeology (especially the location of the underlying water table)
Geologic mapping is critical. There must be at least 10 meters between the base of the landfill and the top of the water table at its shallowest point - this includes anomalous shallow aquifers such as "perched aquifers" on top of impermeable subsurface structures. Why? Because during an event of high infiltration the main water table may become hydrologically connected with the perched aquifer.
Some important factors to consider:
Natural filtration of the subsurface - depending on the nature of the soils and rock, contaminants may be removed from leachate before they reach the water table. Filtration can occur by a number of mechanisms such as ion exchange or sorption.
Dispersion possibilities - migration will occur as a result of both physical and chemical gradients. It is important to determine such things as the presence of subsurface fractures etc. (see above: discussion on Deep Well Injection)
Precipitation possibilities - especially for heavy metals. Do conditions exist in the subsurface that would cause heavy metals to precipitate out of leachate, or will they remain suspended?
GENERAL GUIDELINES FOR SELECTING A LANDFILL SITE
Any location that makes a GOOD AQUIFER (ie. limestone, fractured bedrock etc.) will be a bad place to put a landfill! Why do you think this is true?
SWAMPS are generally poor locations (unless they are drained in which case they are excellent landfill sites due to the high sorptive capacity of peat for heavy metals).
CLAY PITS are a satisfactory location IF THEY ARE DRY! (leachate can readily migrate through wet clay).
FLAT, UPLAND AREAS are okay (such as mesas or benches).
FLOOD PLAINS - absolutely no way!
Any PERMEABLE MATERIAL in conjunction with a HIGH WATER TABLE is a poor location (ex. loess soils in a humid region).
ROUGH TOPOGRAPHY (such as hills or canyons) are acceptable if you stay high up in the valley head.
HERE ARE TWO REPRESENTATIVE SITES:
|
Semi-arid Site |
Humid Site |
A thought question: You are in charge of selecting a new site for an urban landfill. After review, three sites are suggested: the first is in an area of low precipitation up on a very steep hillside; the second is in an area of moderate precipitation overlying a highly impermeable aquifer; the third site is in an area of low precipitation but overlies a sole source drinking water aquifer. Where would you put the landfill? Why?
THE GOAL
OPTIMIZE SITE LOCATION WITH RESPECT TO SURFACE AND GROUNDWATER SYSTEMS!REMEMBER
ALWAYS DO YOUR GEOLOGIC/HYDROGEOLOGIC ASSESSMENT BEFORE YOU COMMIT TO A SITE!MONITORING of conditions at the landfill site is crucial, and should begin prior to commencement of landfill operations in order to establish background, "natural" conditions. This provides a baseline for comparative purposes for the landfill. This data should be collected over several years in order to characterize normal conditions for the full range of natural events. Once landfill operation begins, constant monitoring for the presence of contamination in the aqueous and gaseous phases must be done. Soil and groundwater should be sampled and tested frequently.
SOME DIFFERENT ROUTES BY WHICH TOXINS CAN ENTER THE ENVIRONMENT FROM A LANDFILL
VOLATILIZATION - puts pollutant gases such as CH4, NH3 and H2S into the atmosphere.
HEAVY METALS - are generally retained by soils in the area (especially Pb, Cr and Fe). These metals can then be bioaccumulated into crops and work their way up the food chain.
SOLUBLE MATERIAL - can enter the groundwater. Chloride, nitrate and sulfate ions are typical contaminants. Soluble pollutants may also complex with heavy metals thus keeping them in solution and creating a leachate with high concentrations of toxic metals.
SURFACE RUNOFF - overland flow through the landfill site can transport contaminants into surface water.
CROPS & PLANTS - in the area may bioaccumulate toxins. Again, these will work their way up the food chain.
PLANT RESIDUES/DETRITUS - that contain bioaccumulated toxins.
SECURE LANDFILLS are specifically designed to accept hazardous wastes. The structure of a secure landfill is similar to that of a sanitary landfill. The difference is that many more layers are used in the cover and liner systems. Also, several more backup leachate/gas collection systems must be installed. This type of disposal facility is regulated under Subtitle C of RCRA. which stipulates ZERO TOLERANCE for materials leaving the system. ALL leachate or any other substances produced must be contained, recovered, and accounted for.
Figure 12.11 in your text has a good diagram of a secure landfill.
All of earth's systems are inextricably intertwined. We can no longer take any of our amenities or actions for granted. Everything that we do will eventually impact us. We are the only ones who can decide whether these impacts will be beneficial or harmful. Let's end with a great quote from Chief Seattle (recorded in 1852):
| anaerobic digester CAA cap/cover CERCLA composting cradle-to-grave CWA deep well injection EPCRA generator hazardous waste heavy metals incineration Industrial Ecology Integrated Waste Management landfill leachate liner Love Canal | point source pollutionnon-point source pollution NPDES NPL ocean dumping on-site disposal recycle sanitary landfill SARA secure landfill soluble Superfund urban runoff volatile waste waste disposal waste management zero tolerance |
TASK 1: Briefly describe one illustrative example for each of the four waste management philosophies discussed in the module.
TASK 2: A.Visit the following Environmental Defense Fund web site to read some facts about plastics recycling. Bureau of International Recycling web site and use the link to recycling information. Scroll to the bottom of the frame that comes up and follow the links to learn more about recycling all kinds of different materials. Find out and list what materials are recyclable in your home town. C. Go to the Northeast Recycling Council recycling data web site to find out which northeastern state has the highest recycling rate, and what that rate is. (HINT: find the most recent statistics) How does this compare to the national average
TASK 3: Visit the EPA's Superfund Web Site and find the Superfund sites in your state. List the three sites closest to your home, and briefly describe what the main contaminants of concern are.
TASK 4: Visit the Idaho Department of Environmental Quality and go to the section concerning industrial hazardous waste (or search your own state or country's Department of Environmental Quality for this information). What are the three categories of waste generators? How many tons of TSD wastes were disposed of last year?
TASK 5: Use the "OVERVIEW OF AVAILABLE DATA" link at:
EPA's Envirofacts Database to request a TOXIC RELEASE INVENTORY datasheet for your home state (use the "Tri State Reports" Link that you will find). Then answer the following questions: A. What is the reporting date for these figures? B. What was the number one chemical released to the air? In what quantity? C. What was the number one facility for air pollution releases? What was the total amount of pollutants they released?TASK 6: GO TO THE Center for Environmental Information. Follow the link for County Level Data. Select your state and then your county and then request a drinking water profile. Learn about your aquifer, then answer this question: What year had the greatest number of health violations by the Community Water System providers?
TASK 7: Learn about household hazardous wastes and then make a list of the hazardous chemicals in your own home. Select three of those chemicals and state a safe alternative to them. http://www.epa.gov/epaoswer/osw/index.htm http://www2.state.id.us/deq/ http://www.environmentaldefense.org/home.cfm http://www.bir.org/ http://www.nerc.org/recycling/index.html http://www.epa.gov/superfund/sites/index.htm http://www.epa.gov/OGWDW/year1/sdwahtm.html http://www.epa.gov/safewater/mcl.html http://www.epa.gov/eq/ http://www.epa.gov/epaoswer/osw/tsd.htm http://www.epa.gov/epaoswer/osw/treatech.htm http://www.epa.gov/epaoswer/non-hw/muncpl/hhw.htm http://www.cwwg.org/Notsafe.html http://www.deq.state.ut.us/EQSHW/CDS/CDS_Main.htm http://ohioline.osu.edu/aex-fact/0707.html http://www.dec.state.ny.us/website/dshm/redrecy/la2.htmBack to ISU Geosciences Web Courses Home
