Saltcrete 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 ...

with

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantitie ...

s and

brine Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for br ...

, usually originating from liquid waste treatment plants. 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 lower-level

radioactive waste Radioactive waste is a type of hazardous waste that contains radioactive material. Radioactive waste is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, rare-earth mining, and nuclear weapons r ...

in the form of solid material. It is a form of

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 ...

. Saltcrete is being replaced by saltstone, which is less permeable and leachable. Saltstone is a mixture of the

salt cake Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 milli ...

(mostly

sodium nitrate Sodium nitrate is the chemical compound with the formula . This alkali metal nitrate salt is also known as Chile saltpeter (large deposits of which were historically mined in Chile) to distinguish it from ordinary saltpeter, potassium nitrate. T ...

and other salts) with

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

and

fly ash Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK) plurale tantum: coal combustion residuals (CCRs)is a coal combustion product that is composed of the particulates (fine particles of burned fuel) that are driven out of coal-fired ...

. An example of a saltcrete site in the United States is The

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 ...

Environmental Technology Site (RFETS) near

Denver, Colorado Denver () is a consolidated city and county, the capital, and most populous city of the U.S. state of Colorado. Its population was 715,522 at the 2020 census, a 19.22% increase since 2010. It is the 19th-most populous city in the Unit ...

. Between 1952 and 1992,

nuclear weapons A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions (thermonuclear bomb), producing a nuclear explosion. Both bomb ...

components consisting of

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

and otherwise

hazardous A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would allow them, even just theoretically, to cause damage to health, life, property, or any other interest of value. The probabi ...

materials were manufactured there. By 1989, a government investigation had concluded that many of these materials were being improperly stored and handled, leading to the site being added to the

National Priorities List The National Priorities List (NPL) is the priority list of hazardous waste sites in the United States eligible for long-term remedial investigation and remedial action (cleanup) financed under the federal Superfund program. Environmental Protec ...

for cleanup by 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 ...

Saltcrete-related background of RFETS

In June 1997 Kaiser-Hill Company, also known as

CH2M Hill CH2M, earlier CH2M Hill, was an engineering company that provided consulting, design, construction, and operations services for corporations and governments. The company was organized in Corvallis, Oregon, and headquartered at 9191 South Jamaic ...

, the DOE Integrating Management Contractor for RFETS, contracted with Envirocare of Utah, Inc., also known as

EnergySolutions EnergySolutions (stylized as Energy''Solutions''), headquartered in Salt Lake City, Utah, is one of the largest processors of low level waste (LLW) in America, making it also one of the world's largest nuclear waste processors. It was formed in 20 ...

, to transport, treat and dispose of more than 13,000 cubic meters of radioactively and hazardously contaminated mixed waste, including the Saltcrete waste stream. Shipment of Saltcrete began in July 1997. The first phase of 1,705 cubic meters of the Saltcrete waste stream was successfully transported, treated and disposed in less than eight weeks. The second phase of 1,710 cubic meters was completed in the first quarter of FY98 in the same amount of time.

Introduction

Saltcrete is the result and technique of

wastewater Wastewater is water generated after the use of freshwater, raw water, drinking water or saline water in a variety of deliberate applications or processes. Another definition of wastewater is "Used water from any combination of domestic, industr ...

processing and was the second-largest mixed waste stream at RFETS requiring treatment and disposition. The majority of wastewater from RFETS production processes is contained in large tanks and then is treated by precipitation, filtration, evaporation, and drying to result in a matrix referred to as "

salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively cha ...

". Original waste stream production was rich in nitrates and sulfates, therefore the reference to the dried material as salts; however, current waste stream production has an essentially decreased concentration of inorganic compounds, even though the waste is still considered to as salts. Saltcrete is formed when liquid evaporator concentrates are combined with the salts and

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 ...

. The mixture is poured into cardboard and plywood containers to solidify into a

monolith A monolith is a geological feature consisting of a single massive rock (geology), stone or rock, such as some mountains. For instance, Savandurga, Savandurga mountain is a monolith mountain in India. Erosion usually exposes the geological for ...

. The process waste water remains hazardous waste Saltcrete is a mixed radioactive waste.{{clarify, reason=garbled language, date=November 2015

Radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

contamination principally includes

americium Americium is a synthetic radioactive chemical element with the symbol Am and atomic number 95. It is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was na ...

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibi ...

, and

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

. The waste carries

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, Hazardous Waste Codes F001, F002, F005, F006, F007, and F009. RCRA contaminants include specific volatile and semi-volatile organic compounds and metals.

Treatment and formula development by the joint-venture

The mutual goal between Envirocare and Kaiser-Hill was to meet the Rocky Flats Cleanup Agreement. The agreement policy was 1,575 cubic meters of non-compliant Saltcrete waste had to be removed from RFETS by September 30, 1997. After agreement award yet prior to shipment to Envirocare, a successful formula had to be developed in time to meet the specified objectives. Benchscale treatability studies were in progress by experimenting five ‘worst-case’ samples of the Saltcrete waste that were collected by Kaiser-Hill. According to the variability of RCRA Hazardous Waste constituents in the waste population, several treatability samples were required. This sample selection was required to make sure that the formula developed would be sufficiently aggressive to stabilize the hazardous elements known to be existed. Formula development services were subcontracted by Envirocare to InSciTe (a subsidiary of Mountain States Analytical Laboratory, Inc.). Formula development was involving the application of several combinations of chemical reagents in an effort to immobilize hazardous constituents. In accordance with existing permit requirements, Envirocare submitted a copy of the Treatment Formula to the State of Utah, Division of Solid and Hazardous Waste. The State retains this report for its reference. Kaiser-Hill was successful in expediting sample selection, collection and delivery to Envirocare for the analysis. Envirocare utilized rush analytical services and an accelerated schedule for result in the formula being developed in under one month. Notification for shipment was provided to Kaiser-Hill immediately upon successful formula development. Finally in 1997, Envirocare has won a $7 million contract to handle low-level mixed waste at the former Rocky Flats nuclear weapons plant.

Site condition criteria

The site-related criteria are used for development of the design for the temporary Reprocessing Facility are also provided in the Process and Project Design Criteria. Numerous of the rules, regulations, guidelines, policies, etc. for a sub-contractor operated, temporary facility have a different principle than those which could be an impact or requirement for a longer-term facility. Furthermore, standards for a processing facility which could be adjusted for a higher variation of feed materials and possibly have the ability to emit different byproduct waste forms such as liquid to solid, are also seemed to be integrated. These new regulations would have to be determined and the well-fitted modifications made to the equipment design criteria, general design criteria, specifications and site-related considerations. These differences would then have to be acknowledged into the construction design. It is similarly that the site-related criteria required for the longer-term plant will not only require a more detailed engineering effort for process design, but also would require greater attention to definition of the site-related factors such as soil bearing pressure, requirements for foundations, vibrational considerations, building criteria, etc.

Disposal of Saltcrete

Treated byproduct will be placed mixed waste cell for permanent disposition. The mixed waste cell is engineered with a triple high-density polyethylene (

HDPE High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density ratio, ...

) liner system. Collected layers between each line provide leak liquid management and leakage detection for the cell, while a foundation of engineered clay stabilizes the liner system. The waste is buried in a 7 ft clay

radon Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colourless, odourless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through ...

barrier, a rock filter zone, and a coarse rock erosion barrier.

External links and references

*1. A. Drom, K. Loveland (n.d.) "SALTCRETE: A PARTNERSHIP IN TREATMENT AND DISPOSAL" http://www.wmsym.org/archives/1998/html/sess49/49-05/49-05.htm *2. E. Welsome (2000)
This Place Is a Dump! Rocky Flats was designed to produce plutonium triggers for nuclear bombs. But what it really produced was waste -- lots of hazardous waste.
*3. Environmental Protection Agency or EPA (n.d.) "Hazardous Waste Code" http://www.lm.doe.gov/cercla/documents/rockyflats_docs/OU04/OU04-A-000420.pdfhttp://www.epa.gov/waste/inforesources/data/br91/na_apb-p.pdf *4. Halliburton Nus Environmental (1992) Corporation "Pondcrete and Saltcrete White Paper, Site Conditions Criteria" http://www.lm.doe.gov/cercla/documents/rockyflats_docs/OU04/OU04-A-000420.pdf *5. UNITED STATES COURT OF APPEALS TENTH CIRCUIT (2001) https://law.resource.org/pub/us/case/reporter/F3/265/265.F3d.1157.99-1353.99-1352.99-1351.html *6. G. K. Marsh, Assoc. LLC. "Trials of the Rocky Flats Nuclear Weapons Plant SuperFund MegaSite Operators: Rockwell International & The Dow Chemical Company."(2006) http://www.forensic-pro.com/tstmny.htm *7. Deseret News "Envirocare wins Rocky Flats waste pact" http://www.deseretnews.com/article/567465/Envirocare-wins-Rocky-Flats-waste-pact.html?pg=all Waste treatment technology Concrete Radioactive waste