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# Drinking Water Treatment Wastes Certain rock types naturally contain radioactive el ements referred to as NORM (Naturally Occurring Radioactiv e Materials). When a source of drinking water comes i n contact with NORM-bearing rocks, radionuclides may accumula te in the water to levels of concern. The predominant rad ionuclides found in water include: radium (and its decay products) thorium (and its decay products) uranium (and its decay products) As water is treated to remove impurities, radionucl ides may collect and eventually build up in filters, tanks, and pipes at treatment plants. The small amounts of NORM present in the source water may concentrate in sediment or sludges . Because the NORM is concentrated due to human activity, it is classified as TENORM (Technologically Enhanced Radioactive Material). Most of this waste is disposed in landfills and lagoons, or is applied to agricultural fields. Most drinking water treatment sludges are thought t o contain radium (Ra-226) levels comparable to typical concentrations in soils. Howe ver, some water supply systems, primarily those relying on groundwater sources, may generate sludge with much higher Ra-226 levels. Furthermore, some water treatment systems are more effective than others in removing naturally-occurring radionuclides from the water.
The table below lists the current radionuclide stan dards for drinking water.
Radionuclide Maximum Contaminant

Level (MCL) Allowed by EPA combined radium 226/228 5 pCi/L uranium 30 μg/L beta emitters 4 mrems gross alpha standard 15 pCi/L 

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- water.htmlRadionuclide Maximum Contaminant Level (MCL) Allowed by EPA radon 300 pCi/L (proposed standard) On this page: Radiation Levels Waste Generation Lime Softening Ion

- Exchange and Activated Charcoal Disposal and Reuse Lagoons Landfills Sewer Systems Deepwell Injection Landspreading and Soil Conditioning What is being done about these wastes?



### Radiation Levels Of the 160,000 public water systems serving the U.S ., approximately 700 of these systems treat water with elevated TENORM levels. The Nation al Inorganics and Radionuclide Survey (NIRS), performed by the EPA, found large numbers o f water treatment plants in the midwestern and southeastern states processing water with radium concentrations in excess of EPA's Maximum Contaminant Levels (MCLs). The con centration and distribution of radionuclides in drinking water varies from one are a to another depending on location variables: geological location groundwater pH redox potential radionuclide solubility and half

- life water withdrawal rates amount of sludge produced per unit volume of water processed. Radium levels are typically found in higher concent rations in groundwater than in surface water. Concentrations in groundwater typically rang e from 0.5-25 pCi/L compared to 0.01-1 pCi/L for surface water. Radium concentrations as h igh as 200 pCi/L have been reported, although this is rare; levels are seldom seen above 50pci/L. Ra-226 average concentration in community drinking water supplies is estimated to range from 0.3 to 0.8 pCi/L . The results of the National Inorganics and Radionuclide Survey (NIRS), performed by the U.S. EPA's Office of Drink ing Water, indicate a higher weighted average of 0.905 pCi/L. Five states—Georgia, Illinoi s, Minnesota,Missouri, and Wisconsin— have been noted to have still higher average concen trations, ranging from 1.27 to 5.29 pCi/L . Uranium activity as high as 652 pCi/L has been obse rved in both surface and groundwater samples. The average uranium concentrations in surf ace and groundwater are believed to be about 1 and 3 pCi/L, respectively. The population-w eighted average uranium concentration in community drinking water supplies is estimated to r ange from 0.3 to 2.0 pCi/L . 

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- water.htmlThe presence of radon in groundwater is known to va ry significantly, with the concentration

being over six orders of magnitude different from t hat of Ra-226. The geometric mean of groundwater radon concentrations is nearly 1,000 pC i/L. For radon, the population-weighted average is believed to range from 194 to 780 pCi/L.



### Waste Generation Approximately 260,000 metric tons (MT) of TENORM wa stes are generated each year by U.S. water treatment facilities. This is equivalent to 6 00 MT of TENORM per utility. Eighty-three percent of the contaminated waste is filter sludge and the remaining 17 percent is ion exchange resins and charcoal. The table below lists typical radiation levels in d rinking water treatment residuals:

Wastes Radiation Level [pCi/g] low average high Treatment Sludge [pCi/l] 1.3 11 11,686 Treatment Plant Filters 40,000
The Radiation in TENORM Summary Table provides a ra nge of reported concentrations, and average concentration measurements of NORM associat ed with various waste types and materials. Not all treatment facilities produce TENORM wastes. The degree of contamination varies according to the natural abundance of radionuclides in the water and on the treatment methods employed. Only 28 percent of water treatmen t processes remove radionuclides from water. Those of most concern are lime softening and ion exchange and activated charcoal.

Lime softening Lime softening is used on large water supply system s to soften water by the addition of calcium hydroxide. Calcium hydroxide raises the pH of water causing calcium and magnesium to settle out and form a solid sludge. 80 to 90 per cent of the radium in the water becomes trapped in the sludge, which is removed by sediment ation and filtration. This process typically produces about 4 cubic yards (3.1 m3) of dewatered sludge per million gallons of processed water.

Ion-Exchange and Activated Charcoal Ion-exchange resins are used on smaller water suppl y systems to soften water by replacing Ca2+ and Mg2+ ions with Na+ ions. In the process, a bout 95 percent of the radium is also removed . However, the resins are usually back wash ed for reuse rather than being disposed. The backwash water, which contains radium, is typic ally discharged to storm sewers, underground injection wells or septic tanks, or is back washed to another ion-exchange 

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- water.htmlcolumn for the selective removal of radium. Radionu clide content eventually builds up in the

resin after prolonged usage.


### Disposal and Reuse A variety of methods are employed for disposing of drinking-water treatment sludge, including lagoons, landfills, sewer systems, deep w ell injection, and land spreading/soil conditioning.

Lagoons Approximately 42 percent of sludge is disposed of i n lagoons. Any radium present in the sludge will settle in bottom sediments which may ha ve to be periodically dredged and properly disposed of.

Landfills Approximately 30 percent of generated sludge is dis posed of in landfills. Contaminated materials are typically covered and compacted on a daily basis. Features such as clay layers are emplaced above and below the buried waste to pr event radon emissions and radionuclides from leaching into the groundwater.

Sewer Systems Approximately five percent of sludge is discharged into sewer systems. Sludge and other wastes released into sanitary sewers are ultimately treated at sewage treatment facilities. Some of the discharged sludge may wind up in storm sewers where it is typically routed to natural bodies of water where sludge may accumulate in aquatic sediments.

Deep-Well Injection Deep-well injection involves the pumping of sludge into a stable geologic formation. Deepwell injection is not commonly used and is specific ally prohibited in the states of Wisconsin and Illinois. Because of its potential adverse impa ct on groundwater aquifers, EPA uses its authority under the Safe Drinking Water Act to cont rol and also discourage this practice.

Land Spreading/Soil Conditioning About 20 percent of sludge is disposed of by land a pplication to improve soil conditions or to fertilize the soil. The sludge is plowed directly i nto the soil to limit water runoff and for sanitary reasons. Recently proposed rules may prohi bit this practice on agriculture land. 

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### What is Being Done About These wastes?

EPA EPA has developed guidance on managing drinking wat er treatment waste and is conducting a study to learn more about the levels of radioacti vity in these wastes. A Regulators' Guide to the Management of Radioactiv e Residuals from Drinking Water Technologies (PDF) (81 pp, 561K [ about pdf format ] ) [EPA 816-R-04-005] This report includes guidance on managing water tre atment wastes and other topics: technologies for treating and removing radionuclide s from drinking water general principles of radioactivity recommendations for occupational safety of workers at the Community Wat er Systems (CWS) including guidance for radiation prot ection and protection from radon regulatory requirements governing the radioactive wastes gener ated by the CWSs. Study of the Levels of Radioactivity in Drinking Wa ter Wastes In a limited radiation study at several Community W ater Systems around the country, EPA is evaluating radiation levels and concentrations of r adionuclides in facilities which treat water for radionuclides. The study will measure radiation levels the facilities: tanks, filters, and other equipment piping and possibly pipe scales source water finished drinking water sludges and sediments

Programs  Topics  References http://www.epa.gov/rpdweb00/tenorm/drinking-water.h tml Last updated on Friday, July 08, 2011 

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