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United StatesEnvironmental ProtectionAgency

Remediation of Radium fromContaminated Soil

EPA/600/R-01/099December 2001

Remediation of Radium fromContaminated Soil

M. MisraR. K. Mehta

P. LanUniversity of Nevada, Reno

Reno, Nevada 89557

Cooperative Agreement No. CR-826147

Project OfficerMary Gonsoulin

National Risk Management Research LaboratoryOffice of Research and Development

U.S. Environmental Protection AgencyAda, Oklahoma 74820

National Risk Management Research LaboratoryOffice of Research and Development

U.S. Environmental Protection AgencyCincinnati, Ohio 45268

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Notice

The U.S. Environmental Protection Agency through its Office of Research andDevelopment partially funded and collaborated in the research described hereunder Cooperative Agreement No. CR-826147 to the University of Nevada, Reno.It has been subjected to the Agency's peer and administrative review and has beenapproved for publication as an EPA document. Mention of trade names orcommercial products does not constitute endorsement or recommendation for use.

All research projects making conclusions or recommendations based onenvironmental data and funded by the U.S. Environmental Protection Agency arerequired to participate in the Agency Quality Assurance Program. This project wasconducted under an approved Quality Assurance Project Plan. The proceduresspecified in this plan were used without exception. Information on the plan anddocumentation of the quality assurance activities and results are available from thePrincipal Investigator.

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Foreword

The U.S. Environmental Protection Agency is charged by Congress withprotecting the Nations land, air, and water resources. Under a mandate of nationalenvironmental laws, the Agency strives to formulate and implement actions leadingto a compatible balance between human activities and the ability of natural systemsto support and nurture life. To meet this mandate, EPAs research program isproviding data and technical support for solving environmental problems today andbuilding a science knowledge base necessary to manage our ecological resourceswisely, understand how pollutants affect our health, and prevent or reduce environ-mental risks in the future.

The National Risk Management Research Laboratory (NRMRL) is the Agencyscenter for investigation of technological and management approaches for prevent-ing and reducing risks from pollution that threatens human health and the environ-ment. The focus of the Laboratorys research program is on methods and theircost-effectiveness for prevention and control of pollution to air, land, water, andsubsurface resources; protection of water quality in public water systems; remediationof contaminated sites, sediments and ground water; prevention and control ofindoor air pollution; and restoration of ecosystems. NRMRL collaborates with bothpublic and private sector partners to foster technologies that reduce the cost ofcompliance and to anticipate emerging problems. NRMRLs research providessolutions to environmental problems by: developing and promoting technologiesthat protect and improve the environment; advancing scientific and engineeringinformation to support regulatory and policy decisions; and providing the technicalsupport and information transfer to ensure implementation of environmental regula-tions and strategies at the national, state, and community levels.

This report presents a discussion of the application of a physico-chemicalseparation process for the removal of radium from a sample of contaminated soilfrom the Ottawa site near Chicago. The size/activity distribution analyzed amongthe particles coarser than 5 micron showed that the activity was uniformly distrib-uted. Almost 50% of the Ra-226 activity was associated with particles of size5 micron and less. These size fractions are: coarse (+300 micron), medium(300 x 10 micron), and fine (-10 micron). On the basis of the test work conducted inthis project, a flowsheet was developed which can be used for on-site demonstra-tion, Figure 38. The report concludes with an outlook of possible future effortsneeded in this research area. It is published and made available by EPA's Office ofResearch and Development to assist the user community.

Stephen G. Schmelling, Acting DirectorSubsurface Protection and Remediation DivisionNational Risk Management Research Laboratory

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The objective of this study was to demonstrate the application of a physico-chemical separation process for the removal of radium from a sample of contami-nated soil at the Ottawa, Illinois, site near Chicago. The size/activity distributionanalyzed among the particles coarser than 5 micron showed that the activity wasuniformly distributed. Almost 50% of the Ra-226 activity was associated withparticles of size 5 micron and less. These size fractions are: coarse (+300 micron),medium (300 x 10 micron), and fine (-10 micron).

A series of mild chloride washing and flotation experiments showed that the+300 micron and 300 x 10 micron size fraction can be remediated below a criterionlevel of 6 pCi/gm. This criterion was based upon the 5 pCi/g plus backgroundstandard of 40 CFR 192. The criterion is often a relevant and appropriate require-ment for Superfund. Also, chemical washing utilizing the chloride based lixiviantswas found to be potentially useful for the remediation of -10 micron soil fraction.The radium from coarse fraction up to 50 mesh (300 micron) could be easilyremoved by screening and chloride washing. However, there was a difficulty inachieving a low radium value in the medium sized fractions using flotation. In orderto accomplish this goal, several different reagents (specific to radium), effect oftemperature and the effect of chloride washing were evaluated.

Experimental results demonstrated that a combination of reagent using(R-801+8-HQ) was uniquely specific for radium. Using the combined flotationreagent, a volume reduction of 80% with a radium level of 6 pCi/gm was obtained.The tests showed that with chloride washing of coarse materials (+300 micron) andflotation of 300 micron x 10 micron, the overall volume reduction of 80% can beaccomplished. The typical results are summarized below:

Abstract

The gross count analysis conducted at the University of Nevada, Reno wasfound to be consistent with the Ra-226 gamma scan data analyzed by ThermoNUtech on the selected samples.

On the basis of the test work conducted in this project, a flowsheet wasdeveloped which can be used for on-site demonstration. This report was submittedin fulfillment of Cooperative Agreement No. CR-826147 by the University ofNevada, Reno under the sponsorship of the United States Environmental ProtectionAgency. This report covers a period from 10/01/97 to 09/30/2000.

RADIUM DECONTAMINATION RESULTS SUMMARY FOR OTTAWA SOIL Contaminated Soil Fraction

Weight % Average Ra-226 Activity (pCi/g)

% of Original Soil as "Clean Soil"After Application of UNR Technologies

+300 micron 43 26.2 40-41 -300 +10 micron 33 92.3 26-30 -10 micron 24 180 19-22

Total Volume Reduction = 85-93%

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Contents

1. Introduction ................................................................................................................................ 1

1.1 Background and Objective ................................................................................................ 11.2 Rationale ........................................................................................................................... 21.3 Scope ................................................................................................................................ 3

2. UNR Soil Washing Laboratory .................................................................................................. 5

2.1 Design ............................................................................................................................... 52.2 Operations ........................................................................................................................ 72.3 Acquisition of Soil and Laboratory Readiness ................................................................... 92.4 Performance Criterion ....................................................................................................... 9

3. Soil Sample Characterization .................................................................................................. 11

3.1 Characterization of the Ra-Contaminated Ottawa Site Soil Sample ................................ 11

4. Description of Mechanical Flotation Technology .................................................................... 17

5. Surrogate Testing .................................................................................................................... 19

5.1 Surrogate Development .................................................................................................. 195.2 Surrogate Characterization ............................................................................................. 19

5.2.1 Surface Charge Measurements ............................................................................. 195.3 Hallimond Tube Flotation Experiments ............................................................................ 19

5.3.1 Effect of Collector Concentration ........................................................................... 195.3.2 Effect of pH ............................................................................................................ 195.3.3 Mixture of Soil and Barite ...................................