Waste pond
Encyclopedia
A waste pond or chemical pond is a small impounded water body used for the disposal of water pollutants, and sometimes utilized as a method of recycling
or decomposing toxic substances. Such waste ponds may be used for regular disposal of pollutant materials or may be used as upset receivers for special pollution events. Often, chemical ponds themselves are addressed for cleanup action after their useful life is over or when a risk of groundwater
contamination arises. Peak usage of waste ponds in the United States occurred in the period 1955 to 1985, after which the environmental risks of pond technology were sufficiently understood, such that alternative technologies for waste disposal gradually began to displace many of the waste ponds. Waste ponds often have pond liners, such as concrete
or robust synthetic polymer
ic materials, to prevent infiltration
of chemicals to soil or groundwater.
during the active phase of plant operation. Its main use was for drainage of chemicals. Hazardous and exotic chemicals would go down drains in the plant to the pond and later be pumped back to the factory via two large pumps. There it would be distilled to remove acetone
and other hazardous chemicals from the mix. This process was overall harmful to the environment and polluted the groundwater
.
operated for more than 50 years, performing research and production at its facility in the Melton Valley area of the Oak Ridge Reservation, in Oak Ridge, Tennessee
, before it was decommissioned in the mid 1960s. One of the results of this activity was a waste pond, which was contaminated with radioactive waste including strontium-90
, caesium-137
; tritium
, and transuranics
.
During the 1970s, the pond was backfilled with clay
and shale
, and finally capped with asphalt
.
In the mid 1990s, as a temporary solution to concerns that soil and sediments could migrate into nearby streams and, ultimately, reservoirs used for recreation and drinking water
supplies, Department of Energy
officials installed a cryogenic
stabilization system at the waste pond, freezing the soil and groundwater to a depth of approximately 30 feet (9.1 m) around the pond, thereby forming a barrier to groundwater leaching.
In February 2004, the cryogenic system was dismantled, replaced with a temporary thermal foam blanket to keep the soil cold, and the pond was excavated. The soil in the areas surrounding the frozen pond contained lower levels of contamination
than the pond itself, but enough contamination that it had to be removed. Approximately 10000 cubic yards (7,645.5 m³) of soil were removed from the surrounding areas. Another 5400 cubic yards (4,128.6 m³) of soil were excavated from the pond itself.
Recycling
Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...
or decomposing toxic substances. Such waste ponds may be used for regular disposal of pollutant materials or may be used as upset receivers for special pollution events. Often, chemical ponds themselves are addressed for cleanup action after their useful life is over or when a risk of groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
contamination arises. Peak usage of waste ponds in the United States occurred in the period 1955 to 1985, after which the environmental risks of pond technology were sufficiently understood, such that alternative technologies for waste disposal gradually began to displace many of the waste ponds. Waste ponds often have pond liners, such as concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
or robust synthetic polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
ic materials, to prevent infiltration
Infiltration (hydrology)
Infiltration is the process by which water on the ground surface enters the soil. Infiltration rate in soil science is a measure of the rate at which soil is able to absorb rainfall or irrigation. It is measured in inches per hour or millimeters per hour. The rate decreases as the soil becomes...
of chemicals to soil or groundwater.
Piscataway chemical pond
One example of a chemical pond is situated in the woods of Piscataway, New Jersey. It was used by Union CarbideUnion Carbide
Union Carbide Corporation is a wholly owned subsidiary of The Dow Chemical Company. It currently employs more than 2,400 people. Union Carbide primarily produces chemicals and polymers that undergo one or more further conversions by customers before reaching consumers. Some are high-volume...
during the active phase of plant operation. Its main use was for drainage of chemicals. Hazardous and exotic chemicals would go down drains in the plant to the pond and later be pumped back to the factory via two large pumps. There it would be distilled to remove acetone
Acetone
Acetone is the organic compound with the formula 2CO, a colorless, mobile, flammable liquid, the simplest example of the ketones.Acetone is miscible with water and serves as an important solvent in its own right, typically as the solvent of choice for cleaning purposes in the laboratory...
and other hazardous chemicals from the mix. This process was overall harmful to the environment and polluted the groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
.
Oak Ridge waste pond
The United States Oak Ridge National LaboratoryOak Ridge National Laboratory
Oak Ridge National Laboratory is a multiprogram science and technology national laboratory managed for the United States Department of Energy by UT-Battelle. ORNL is the DOE's largest science and energy laboratory. ORNL is located in Oak Ridge, Tennessee, near Knoxville...
operated for more than 50 years, performing research and production at its facility in the Melton Valley area of the Oak Ridge Reservation, in Oak Ridge, Tennessee
Oak Ridge, Tennessee
Oak Ridge is a city in Anderson and Roane counties in the eastern part of the U.S. state of Tennessee, about west of Knoxville. Oak Ridge's population was 27,387 at the 2000 census...
, before it was decommissioned in the mid 1960s. One of the results of this activity was a waste pond, which was contaminated with radioactive waste including strontium-90
Strontium-90
Strontium-90 is a radioactive isotope of strontium, with a half-life of 28.8 years.-Radioactivity:Natural strontium is nonradioactive and nontoxic, but 90Sr is a radioactivity hazard...
, caesium-137
Caesium-137
Caesium-137 is a radioactive isotope of caesium which is formed as a fission product by nuclear fission.It has a half-life of about 30.17 years, and decays by beta emission to a metastable nuclear isomer of barium-137: barium-137m . Caesium-137 is a radioactive isotope of caesium which is formed...
; tritium
Tritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
, and transuranics
Transuranium element
In chemistry, transuranium elements are the chemical elements with atomic numbers greater than 92...
.
During the 1970s, the pond was backfilled with clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
, and finally capped with asphalt
Asphalt
Asphalt or , also known as bitumen, is a sticky, black and highly viscous liquid or semi-solid that is present in most crude petroleums and in some natural deposits, it is a substance classed as a pitch...
.
In the mid 1990s, as a temporary solution to concerns that soil and sediments could migrate into nearby streams and, ultimately, reservoirs used for recreation and drinking water
Drinking water
Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...
supplies, Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
officials installed a cryogenic
Cryogenics
In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit,...
stabilization system at the waste pond, freezing the soil and groundwater to a depth of approximately 30 feet (9.1 m) around the pond, thereby forming a barrier to groundwater leaching.
In February 2004, the cryogenic system was dismantled, replaced with a temporary thermal foam blanket to keep the soil cold, and the pond was excavated. The soil in the areas surrounding the frozen pond contained lower levels of contamination
Soil contamination
Soil contamination or soil pollution is caused by the presence of xenobiotic chemicals or other alteration in the natural soil environment....
than the pond itself, but enough contamination that it had to be removed. Approximately 10000 cubic yards (7,645.5 m³) of soil were removed from the surrounding areas. Another 5400 cubic yards (4,128.6 m³) of soil were excavated from the pond itself.