Pondcrete is a mixture of

cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mix ...

and

sludge Sludge is a semi-solid slurry that can be produced from a range of industrial processes, from water treatment, wastewater treatment or on-site sanitation systems. For example, it can be produced as a settled suspension obtained from conventiona ...

. Its role is to immobilize

hazardous waste Hazardous waste is waste that has substantial or potential threats to public health or the environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits: ignitability, reactivity, co ...

and, in some cases, low-level and mixed-level radioactive waste, in the form of solid material. The material was used by the

United States Department of Energy The United States Department of Energy (DOE) is an executive department of the U.S. federal government that oversees U.S. national energy policy and manages the research and development of nuclear power and nuclear weapons in the United Stat ...

and its contractor,

Rockwell International Rockwell International was a major American manufacturing conglomerate involved in aircraft, the space industry, defense and commercial electronics, components in the automotive industry, printing presses, avionics and industrial products. R ...

, in an attempt to handle the radioactive waste from contaminated ponds in the

Rocky Flats Plant The Rocky Flats Plant was a U.S. manufacturing complex that produced nuclear weapons parts in the western United States, near Denver, Colorado. The facility's primary mission was the fabrication of plutonium pits, which were shipped to ot ...

for burial in Nevada desert.

Portland cement Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th c ...

is mixed with

to solidify into “pondcrete” blocks and placed into large, plastic lined boxes. The sludge is taken from solar evaporation ponds which are used to remove moisture from waste materials, therefore reducing their weight. To do this, liquid waste is poured into artificial, shallow ponds. The waste is heated by solar radiation and any moisture is evaporated, leaving behind the waste. These ponds contained low level radioactive process waste as well as sanitary sewage sludge and wastes, which categorize them and the Pondcrete as a

mixed waste Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor Value (economics), economic v ...

Radioactive waste

Because the blocks were classified as mixed-level radioactive waste, including plutonium,

was unable to store the blocks in the Nevada Test site. The Nevada Test Site did not have a permit to store mixed-level radioactive waste, so the blocks were left in temporary storage at

Rocky Flats The Rocky Flats Plant was a U.S. manufacturing complex that produced nuclear weapons parts in the western United States, near Denver, Colorado. The facility's primary mission was the fabrication of plutonium pits, which were shipped to ot ...

. Due to problems in production, many of the blocks did not harden correctly and eventually began to seep from the boxes causing large scale environmental contamination of the area. The blocks containing plutonium-239, radioactive waste with a half-life of 24,100 years, had failed in a year. Despite warnings by engineer Jim Stone that the blocks would most likely fail earlier than expected, the blocks were still produced. Later it would be Jim Stone who would file a lawsuit against the company, claiming that they had concealed environmental, safety and health problems from the

Investigation

The contaminations led to an investigation of the Plant by the

Federal Bureau of Investigation The Federal Bureau of Investigation (FBI) is the domestic intelligence and security service of the United States and its principal federal law enforcement agency. Operating under the jurisdiction of the United States Department of Justice, ...

and the

Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale f ...

which eventually resulted in its shutdown.{{cite web, title=Colorado Federal District Court Report of the Federal District Special Grand Jury 89-2, url=http://www.constitution.org/jury/gj/rocky_flats/rocky-flats-grand-jury-report.htm, work=January 24, 1992, publisher=Constitution.org, accessdate=12 February 2018, url-status=bot: unknown, archiveurl=https://web.archive.org/web/20160107032001/http://www.constitution.org/jury/gj/rocky_flats/rocky-flats-grand-jury-report.htm, archivedate=7 January 2016 In 1993, Federal Judge Sherman Finesilver, approved the release of the Colorado Federal District Court Special Grand Jury Report on the investigation. The report found that the Department of Energy and the Environmental Protection Agency oversight were not performed adequately to protect the environment, and that Rockwell did not comply with environmental laws at the Rocky Flats Plant. The

(DOE) and Rockwell violated the

Resource Conservation and Recovery Act The Resource Conservation and Recovery Act (RCRA), enacted in 1976, is the principal federal law in the United States governing the disposal of solid waste and hazardous waste.United States. Resource Conservation and Recovery Act. , , ''et seq ...

(RCRA) by illegally storing, treating and disposing of residues in more than 17,000 blocks of pondcrete and

saltcrete Saltcrete is a mixture of cement with salts and brine, usually originating from liquid waste treatment plants. Its role is to immobilize hazardous waste and in some cases lower-level radioactive waste in the form of solid material. It is a form o ...

in plastic lined cardboard containers outdoors on the 904 Pad at the plant. Each pondcrete block containing mixed-wastes (radioactive, cadmium, methylene chloride and acetone) weighed between 1,500 and 1,800 pounds. These blocks did not sufficiently harden like concrete, maintaining a consistency of wet clay. Many of the boxes ruptured, possibly due to extreme temperature fluctuations in that region of Colorado, spilling these wastes onto the asphalt pad at Site 904. Rain and wind carried these wastes into drainage areas and into the air and soil.

References

Concrete Radioactive waste Waste treatment technology

Radioactive waste

Investigation

See also

References