ML20206H617
| ML20206H617 | |
| Person / Time | |
|---|---|
| Issue date: | 02/05/1986 |
| From: | Gillen D, Gupta D, Nataraja M NRC |
| To: | |
| Shared Package | |
| ML20206H509 | List: |
| References | |
| NUDOCS 8606260227 | |
| Download: ML20206H617 (22) | |
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TESTING AND INSPECTION OF REMEDIAL ACTIONS AT INACTIVE URANIUM MILL TAILING SITES by Dinesh C. Gupta, Mysore S. Nataraja and Daniel M. Gillen Nuclear Regulatcry Commission, Washington, D.C.
Paper to be submitted for the Eighth Annual Symposium On Geotechnical and Geohydrological Aspects of Waste Management to be held at Colorado State University Fort Collins, Colorado February 5, 6, 7, 1986 I
8606260227 860619 PDR MISC PDR 8606260147 1-
Tcsting and Inspsetion of Rsssdial Actions at Insceiva Uranium Mill Tailing Sites Dinesh C. Gupta U.S. Nuclear Regulatory Commission, Washington, DC Mysore S. Nataraja U.S. Nuclear Regulatory Commission, Washington, DC Daniel M. Gillen U.S. Nuclear Regulatory Commission, Washington, DC i
1 ABSTRACT I DOE is responsible for planning and conducting remedial actions for stabilization of inactive uranium mill tailings in accordance with EPA standards. The options presently being considered and implemented by the DOE for stabilization of the inactive tailings consist of (1) stabilization of tailings in place. (ii) stabilization on site, and (iii) relocation and stabilization of tailings at another location. The-detailed design and construction procedure for each remedial action depends upon the site-specifi'c plan selected by the DOE.
Title I of the Uranium Mill Tailings Radiation Control Act of 1978, as amended (UMTRCA) requires Nuclear Regulatory Commission (NRC) concurrence in DOE's selection and performance of remedial actions at inactive uranium mill tailings sites. Among the specific technical aspects of the remedial action performance is field control, including testing and inspection.
The objective of NRC's review and concurrence with DOE's remedial action plans is the verification of compliance with the requirements of the EPA standards issued pursuant to the UMTRCA. To meet this objective, the DOE's remedial action plan and construction must assure adequacy of (i) geotechnical stability, (ii) erosion protection, (iii) raden attenuation, and (iv) protection against existing and future groundwater contamination. Acceptance testing and adequate inspection during construction are essential to assure compliance with specification requirements and to provids confidence that the intended design criteria are la.plemented during construction.
The paper identifies remedial action inspection plan features related to geotechnical engineering that may be necessary to control, verify, and document the DOE's remedial action activities.
Basically, the extent of inspection and testing should be sufficient to provide adequate quality control, to satisfy requirements of-plans and specifications, and to furnish the necessary permanent record. Also, it is essential that the personnel performing the
- inspection.and testing have the required training and experience to perform a professional job.
2 INTRODUCTION Title I of the Uranium Mill Tailings Radiation Control Act of 1978, as amended (UMTRCA) requires Nuclear Regulatory Commission (NRC) concurrence in DOE's selection and performance of remedial actions at inactive uranium mill tailings sites. The NRC provides reviews and concurrences during the remedial process. Among the specific technical aspects of the remedial action performance is field control, including testing and inspection.
DOE is responsible for planning and conducting remedial actions for stabilization of inactive uranium mill tailings in accordance with EPA standards. The options presently being considered and implemented by the DOE for stabilization of the inactive tailings consist of (i) stabilization of tailings in place, (ii) stabilization on site, and (iii) relocation and stabilization of tailings at another location. The detailed design and construction procedure for each remedial action depends upon the site-specific plan selected by the DOE.
The objectis, of NRC's review and concurrence with DOE's remedial action plans is the verification of compliance with the requirements of the EPA standards issued pursuant to the UMTRCA. To meet this obj ective , the DOE's remedial action plan and construction must assure adequacy of (i) geotechnical stability. (ii) erosion protection, (iii) radon attenuation, and (iv) protection against existing and future groundwater contamination. Acceptance testing and adequate inspection during construction are essential to assure compliance with specification requirements and to provide confidence that the intended design criteria are implemented during construction.
This paper describes the engineering practices, testing, inspection, record keeping, nonconformance corrective action and "stop work order" controls considered satisfactory for the implementation of remedial action programs. These criteria reflect the approaches and state-of-the-art methods that are considered to be adequate to protect public health and safety.
3 TESTING AND INSPECTION APPROACH The establishment of the adequacy of construction is usually accomplished by visual examination, measurements, and testing. The extent of inspection and testing ehould be sufficient to provide adequate quality control, to satisfy requirements of plans and specifications, and to furnish the necessary permanent record.
Also, it is essential that the personnel performing the inspection and testing have the required training and experience to perform a professional job.
It is impracticable to test completely all the work performed. A generally acceptable procedure would be to select samples of the work or materials for testing which are representative of some unit of work or material. Conditions which produce test results below the requirements should be remedied. For each failing test, ;
representative sampling and testing should be accomplished before the material is accepted. If there is an appreciable number of borderline test results, immediate steps should be taken to ascertain the cause and to correct it. j I
4 TESTING AND INSPECTION PLAN 4.1 Foundation and Subgrade Prior to placing the first layer of asterial on the foundation, a final inspection of the subgrade should be made to assure that it has no sign of deterioration due to frost action, erosion due to rainwater, rutting, areas of subsidence, or drying out of the surface. The inspection should verify that the foundation surface-has been moistened, but there is no standing water on the surface.
Proof rolling should be required if density testing of the subgrade has not been performed. In addition, the inspection should also verify that the foundation surface of cohesive soils has been scarified or penetrated by taaping rollers to insure proper bonding of material. Any unacceptable surface material should be either i removed or excavated and recompacted to design specifications.
4.2 Capillary Break (non-cohesive)
, Capillary break materials should be inspected and tested to verify that the gradation requirements of the materials have been met.
Testing of in-place capillary break materials should be accomplished to assure that the in-place density of tha materials is in conformance with the specified percentage of maximum relative density.
I 4.3 Geotextile Separators In some Remedial Action Plans, a geotextile separator may be specified for placement between two different construction
, materials. This separator should be inspected te verify that the specified fabric is being used and that the fabric has no tears and has sufficient overlap of material between adjoining pieces when emplaced.
4.4 Seepage Barrier / Liner (Cohesive)
Inspection and testing of seepage barrier / liner materials should include verification that gradation, classification, plasticity index, and the moisture-density relationship conform with the specifications.
4
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4.5 Toilingo/ Conte:inetsd Material Inspection and testing of tailings / contaminated material should be accomplished to assure that the quantity and maximum size of foreign material placed in the encapsulation cell is in conformance with the applicable specifications. Compaction of tailings around the relatively large sized foreign material should meet the specified requirements. Inspection should also+ verify that organic materials are uniformly distributed throughout the emplaced tailings.
Compaction testing should be accomplished to assure that the in-place density and moisture content of the emplaced tailings are in compliance with applicable specifications.
4.6 Radon Barrier / Soil Covers Materials for the radon barrier / soil cover should be inspected and tested to ensure verification of gradation, plasticity index, classification, and moisture-density relationship to conform with the specifications. Testing of in-place det.sity should also be accomplished to ensure compliance with appropriate compaction specifications.
4.7 Filter Bed Inspection of filter bed materials emplacement should be accomplished to assure that they are being properly placed. Testing of emplaced materials should be accomplished to assure that the gradation is in conformance with applicable specifications.
Inspection should assure that the gradation of filter materials are not altered by segregation at the time of emplacement or by physical breakdown of grains by compaction equipment.
L 4.8 Riprap The placement of the riprap materials should receive inspection to assure that proper placement techniques are employed to prevent degradation of the material due to improper handling, to assure that the distribution is uniform and that voids are kept as small as possible, and to assure proper gradation. The inspection should also verify that the size and classification of riprap rock, the lift thickness, and elevations comply with applicable specifications and drawings. Inspection of riprap quality may be provided at the material source if required to assure compliance to the !
specification requirements. The testing should include durability tests such as specific gravity, soundness, abrasion, and absorption.
Inspection of riprap at placement should include visual inspection i of size and shape of riprap materials to ensure that riprap is nonsegregated (free of pockets of small stones or of clusters of large stones), that the gradation tolerance is met and that the riprap is not emplaced in layers.
4.9 Tcp Soil If top soil is used over the riprap, the inspection should assure that the loose thickness of the top soil conforms with the specifications. The inspection and testing should also verify that the lower layers of top soil are adequately compacted. The inspection should further verify that the upper layers of the top soil are seeded as per specifications.-
5 TESTING AND INSPECTION PROCEDURE 5.1 Materials certification Materials which are supplied for installation or which require certification should be verified by the RAC's proj ect quality department as having met the specified requirements. Appropriate tests should be run whenever there is a visible change in ,
engineering characteristics of the material. The inspector should sign or initial the transmittal indicating acceptance or describing the reason (s) for non-acceptance.
5.2 Instrument Certification Instrumentation which is received should be inspected by the person responsible for using and maintaining the instrument. The instrument should be inspected for damage, for correct operation, and for proper calibration records. Equipment which does not meet the applicable requirements should not be used.
The calibration records should be included in the RAC's instruments calibration system. The system should identify the required frequency of calibration checks and methods of calibration for various instruments.
5.3 Compaction Evaluation Procedure Inspections and testing should assure that specified materials are emplaced and compacted as designated on drawings. The loose thickness of the lifts of material and elevations should be verified frequently to ensure compliance to the specification requirements for the particular type of material emplaced. Inspection should also verify that the compaction equipment (or equivalent), as per specifications, is being used for compacting the material and the number of roller passes meets the specification requirements.
In-place field dznsity tacto end cufficiant icborctory moicture-density tests should be performed to further evaluate compaction.
However, the testing procedure should not jeopardize the integrity of the emplaced materials. The field density and moisture testing should be in accordance with ASTM D-698, ASTM D-1557, AS'Di D-4253 and D-4254, ASTM D-1556 or ASTM D-2922, as applicable. The moisture content may also be determined by AASHTO T217 procedure, using the speedy moisture meter. However, when the speedy moisture tests are l
used, a correlation with oven drying method should be developed for each tanth test. If it is necessary to calibrate the moisture meter af ter every tenth test, then more frequent correlations shculd be obtained.
The field test frequency should be a minimum of one test per 1,000 cubic yards of contaminated material placed and one test per 500 cubic yards of other compacted materials including seepage barrier and/or radon barrier earth cover. There should be a minimum of two tests taken for each day that an appreciable amount of fill is placed (in excess of 150 cubic yards). There should be a minimum of one test per lift and at least one test for every full shift of compaction operations.
Prior to the start of field compaction operations, appropriate laboratory compaction curves should be obtained for the range of emplaced materials. During construction, one point Proctor tests at a frequency of one test for every five field density tests on cohesive materials should be performed. Similar checks should be provided for verifying relative densities of non-cohesive materials.
Supplementary laboratory compaction curves (based on complete Proctor tests) should be obtained, approximately one for every 10 or 15 field tests, depending on the variability of materials.
The field determination of moisture and density should be compared with the appropriate compaction curve to evaluate conformance with requirements. The Remedial Action Inspection Plan should include a criterion for evaluating the inspected field density and moisture data based on a continuous review of data.
5.4 Gradation and Classification Testing The placement of materials should receive continuous inspection and frequent verification testing to assure that specification requirements with respect to gradation and classification are maintained. The inspection should assure that the maximum particle size in the emplaced material meets the specified requirements. For all materials other than contaminated materials, at least one gradation test should be run for each day of significant material placement (in excess of 150 cubic yards). Random samples obtained from material being placed should be used for these tests.
Inspection may also be provided at the material source to assure compliance with the specification requirements. Documentation of the test results should be on appropriate laboratory test report sheets and results of visual inspection should be documented in the daily inspection report.
S 5.5 Atterberg Limits Tests Inspections should assure that the proper material is placed as designated on the drawings. Verification testing should include determination of plasticity index, which determines the range of i water content over which a cohesive soil behaves plastica 11y. The tests should be run at least . once for each day of significant cohesive cover or liner material placement (in excess of 150 cubic yards). The samples should be randomly selected. The test results should be documented in the laboratory test reports.
5.6 Rock Durability Tests For each gradation of riprap, rock durability tests such as specific gravity, absorption, sodium or magnesium sulfate soundness, and abrasion testing should be performed prior to delivery of any material to the site. The testing program may vary from site to j site and is dependent on the type of rock selected and the expected environmental stresses that it will be subject to. During construction activities, additional test series should be performed for each type of riprap when approximately one-third and two-thirds of the total volume of each type of riprap have been delivered. For any type of riprap where the volume is greater than 30,000 cubic
, yards, a test series should be performed for each additional 10,000 cubic yards of riprap delivered. A final sample should be obtained for each riprap type following completion of delivery of the material.
5.7 Distribution of Organics i Continuous visual observation during placement of organics in the encapsulation cell should be accomplished to assure that the organic material is uniform and evenly distributed. Also, the inspection should assure that the maximum size of the emplaced organic material does not exceed the specified requirements. Results of visual inspection should be documented on the daily inspection report.
6 NON-CONFORMANCES, CORRECTIVE ACTION AND STOP WORK ORDERS i
- The Remedial Action Inspection Plan should establish procedures to define, identify, and document non-conformances or deviations from plans, specifications, or procedures. A mechanism to develop, control, approve and implement the necessary corrective action should also be established. Follow-up procedures to assure that-proposed corrective actions have been implemented should be documented.
i The plan should also address provisions for a "Stop Work Order".
j The situations when a "Stop Work Order" may become necessary should be described. Procedures and level of authority for issuing
! a "Stop Work Order" should be established and a mechanisa for resolving the corresponding nonconformance(s) should be discussed.
7 RECORDS Daily inspection reports should be written that address the adequacy, progress, and details of construction activities. The reports should include the results of visual inspection, mea surements , and tests performed in the laboratory and in the fsaid. The inspection and test status should be identified by chairs, as-builts, or by periodic status reports. The inspector siic%d summarize volume of emplaced materials and the number of field and laboratory tests performed on each material on a weekly ;
basis. The status of inspection and testing should be monitored as appropriate to prevent inadvertently by-passing an inspection point.
The inspection and test reports should become part of the permanent record of the implementation of the remedial action plan.
Test records should include date, name of tester or inspector, items inspected or tested, type of inspection or test, identification of test method, results, acceptability and acceptance criteria, and name and initials of the reviewer. The records should also identify the testing equipment or instrument used in performing
- the test. When documenting deviations, nonconformances, and stop work order situations, the report should provide sufficient details so that acceptability of the necessary corrective action and final resolution can be independently reviewed.
i 8 CONCLUDING REMARKS This paper has identified remedial action inspection plan features related to geotechnical engineering that may be necessary to control, verify, and document construction a etivities during remedial action at inactive uranium mill tailings sites. Since conditions are likely to vary from site to site, the various remedial action inspection plans may differ in scope and extent. As seen from the discussion presented in the paper, most of the aspects of testing and inspection plans for these remedial actions are similar to those for the construction of other safety related earth structures. However, the following unique aspects of testing and field inspection prgrac:s are associated with the inactive uranium mill tailings sites:
(i)In most cases, the inactive uranium mill tailings are located in or are being relocated to remote areas. Also, unlike active !
tailings impoundments, the impounded waste has undergone significant l drying and includes no free liquids. Therefore, it is expected that the consequences of an embankment failure under these conditions would not be as significant, with the possible exception of an impoundment adjacent to a surface water feature. The scope of the j construction and inspection testing program should be established I recognizing the site specific variation in failure consequences. i l
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(ii) An 12 portent sepset of tha strbility of tha tellings pileo is the material's vulnerability to liquefaction and flow under seismic conditions. Inactive tailings that are to be stabilized in place, are generally partially saturated and therefore, a total liquefaction may not be possible. However, under vibratory loading, significant flow of materials is possible due to localized liquefaction of the- tailings or liquefaction of the subgrade. The earthwork operations intended to improve these aspects of the stability of the piles should generally receive considerable attention during inspection and testing of the remedial action activities.
(iii)The remedial actions at inactive mill tailings impoundments must be implemented so that the reclaimed sites meet appropriate EPA standards for the attenuation of radon release. Field control of cover materials, necessary to implement this aspect of the remedial action, is substantially different from that required for the construction control of many other earthwork projects.
(iv)The concern for the differential settlement of the remediated tailings is large because of the long time period (200-1000 years) of stability requirements with no reliance on routine maintenance during this period. Potential for development of cracks and/or preferential drainage pathways in the earth cover (radon barrier) resulting from differential settlement, and the resulting erosion are of major concern during testing and inspection of the remedial action. Likewise, the long-term stability requirements necessitate ,
greater concern for erosion protection durability than would t normally be applied to other earthwork operations.
In summary, construction of these remedial action plans must assure adequacy of geotechnical stability, erosion protection, radon attention and protection against groundwater contamination. It is essential to assure that the specifications and design criteria for the remedial actions are appropriate to meet the performance standards, and that necessary and sufficient testing and inspection during construction are performed to verify that the remedial action program is properly implemented.
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BIBLIOGRAPHY 3
Gupta Dinesh C., et.al., " Seismic Design Considerations for Uranium i
Mill Tailings Disposal Facilities," Seventh Annual Symposium on Management of Uranium Mill Tailings, Low-Level Waste, and j Hazardous Waste, Colorado State University, Fort Collins, l Colorado, February 6-8, 1985.
t Gillen Daniel M., "Geotechnical Considerations in the NRC's Review of Uranium Mill Tallings Remedial Action Plans," Seventh Annual Symposium on Management of. Uranium Mill Tailings, Low-Level Waste, and Hazardous Waste, Colorado State University, Fort Collins, Colorado, February 6-8, 1985.
Kane J. D., " Design, Inspection and Regulation of Uranium Mill -
Tailings Retention Facilities," Proceedings of the 13th Annual Lecture Series of Geotechnical Group, Philadelphia Section of the ASCE on Geotechnics.of Waste Management, July 1983.
! U.S. Nuclear Regulatory Commission, ,"pesign, Construction, and Inspection of Embankment Retention ' Systems for Uranium Mills,"
Regulatory Guide 3.11, Revision 2, 1977.
U.S. Nuclear Regulatory Commission, " Operation, Inspection and Surveillance of Embankment Retention Systems for Uranium Mill ,
i Tailings," Regulatory Guide 3.11.1, Revision 1, October 1980. ?
Interagency Committee on Dam Safety, Design Earthquake Task Group -
Subcommittee 1, " Proposed Federal Guidelines for Earthquake Analyses and Design of Dams," November 1984.
U.S. Nuclear Regulatory Commission, " Consolidation of Tailings,"
USNRC Report NUREG/CR-3204, October 1983.
U.S. Nuclear Regulatory Commission," Recommended Radiation Protection
~
, Practices for Low-Level Waste Disposal Sites," USNRC Report NUREG/
CR-3343, December 1983.
1 Code of Federal Regulations, 10 Part 40, Appendix A - January 1984.
i U.S. Nuclear Regulatory Commission, Staff Technical Position on ,
" Testing and Inspection Plans during Construction of DOE's Remedial Action at Inactive Uranium Mill Tailing Sites," September 1985.
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TESTING AND INSPECTION OF REMEDIAL ACTIONS AT INACTIVE URANIUM MILL TAILING SITES by Dinesh C. Gupta, Mysore S. Nataraja and Daniel M. Gillen Nuclear Regulatory Commission, Washington, D.C.
Paper to be submitted for the Eighth Annual Symposium On Geotechnical and Geohydrological Aspects of Waste Management to be held at Colorado State University Fort Collins, Colorado _ _. _ ___ __ ._
February 5, 6, 7, 1986 4
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Tssting and Inspzetien of Rsasdial Actions at Inictive Uranium Mill Tailing Sites Dinesh C. Gupta U.S. Nuclear Regulatory Commission, Washington, DC Mysore S. Nataraja U.S. Nuclear Regulatory Commission, Washington, DC
, ___ .. Daniel M. Gillen ~~~~
U.S. Nuclear Regulatory Commission, Washington, DC 4
1 ABSTRACT DOE is responsible for planning and conducting remedial actions for stabilization of inactive uranium mill tailings in accordance with EPA standards. The options presently being considered and implemented by the DOE for stabilization of the inactive tailings consist of (1) stabilization of tailings in place. (ii) stabilization on site, and (iii) relocation and stabilization of tailings at another location. The detailed design and construction procedure for each remedial action depends upon the site-specific plan selected by the DOE.
Title I of the Uranium Mill Tailings Radiation Control Act of 1978, as amended (UMTRCA) requires Nuclear Regulatory Commission (NRC) concurrence in DOE's selection and performance of remedial actions at inactive uranium mill tailings sites. Among the specific technical aspects of the remedial action performance is field
- control, including testing and inspection.
The objective of NRC's review and concurrence with DOE's remedial action plans is the verification of compliance with the requirements of the EPA standards issued pursuant to the UMTRCA. To meet this objective, the DOE's remedial action plan and construction must assure adequacy of (i) geotechnical stability, (ii) erosion protectica, (iii) radon attenuation, and (iv) protection against existing and future groundwater contamination. Acceptance testing and adequate inspection during construction are essential to assure compliance with specification requirements and to provide confidence that the intended design criteria are implemented during
~-
construction. -
The paper identifies remedial action inspection plan features related to geotechnical engineering that may be necessary to control, verify, and document the DOE's remedial action activities.
Basically, the extent of inspection and testing should be sufficient to provide adequate quality control, to satisfy requirements of plans and specifications, and to furnish the necessary permanent ~
record. Also, it is essential that the personnel performing the inspection and testing have the required training and experience to perform a professional job.
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2 INTRODUCTION Title I of the Uranium Mill Tailings Radiation Control Act of 1978, as amended (UMTRCA) requires Nuclear Regulatory Commission (NRC) concurrence in DOE's, selection and performance of remedial actions at inactive uranium mill tailings sites. The NRC provides reviews and concurrences during the remedial process. Among the specific technical aspects of the remedial action performance is field control, including testing and inspection.
DOE is responsible for planning and conducting remedial actions for stabilization of inactive uranium mill tailings in accordance ,
with EPA standards. The options presently being considered and !
implemented by the DOE for stabilization of the inactive tailings 1 consist of (i) stabilization of tailings in place, (ii) stabilization on site, and (iii) relocation and stabilization of tailings at another location. The detailed design and construction procedure for each ' remedial action depends upon the site-specific plan selected by the DOE.
The objective of NRC's review and concurrence with DOE's remedial '
action plans is the verification of compliance with the requirements of the EPA standards issued pursuant to the UMTRCA. To meet this objective, the DOE's remedial action plan and construction must assure adequacy of (i) geotechnical stability, (ii) erosion protection, (iii) radon attenuation, and (iv) protection against
< existing and future groundwater contamination. Acceptance testing and adequate inspection during construction are essential to assure compliance with specification requirements and to provide confidence that the intended design criteria are implemented during
. construction.
This paper describes the engineering practices, testing, inspection, record keeping, nonconformance corrective action and "stop work order" controls considered satisfactory for the implementation of remedial action programs. These criteria reflect the approaches and state-of-the-art methods that are considered to be adequate to protect public health and safety.
3 TESTING AND INSPECTION APPROACH The establishment of the adequacy of construction is usually accomplished by visual examination, measurements, and testing. The extent of inspection and testing should be sufficient to provide i
adequate quality control, to satisfy requirements of plans and specifications, and to furnish the necessary permanent record.
Also, it is essential that the personnel performing the inspection - --
4 and testing have the required training and experience to perform a professional job.
It is impracticable to test completely all the work performed. A generally acceptable procedure would be to select samples of the work or materials for testing which are representative of some unit of work or material. Conditions which produce test results below the requirements should be remedied. For each failing test, representative sampling and testing should be accomplished before the material is accepted. If there is an appreciable number of borderline test results, immediate steps should be taken to ascertain the cause and to correct it.
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4 TESTING AND INSPECTION PLAN 4.1 Foundation and Subgrade Prior to placing the first layer of material on the foundation, a
< final inspection of the subgrade should be made to assure that it has no sign of deterioration due to- frost action, erosion due to rainwater, rutting, areas of subsidence, or drying out of the i surface. The inspection should verify that the foundation surface has been moistened, but there is no standing water on the surface. ~ ~ ~ - ' ~ ^ - - - ~ ~ '
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Proof rolling should be required if density testing of the subgrade has not been performed. In addition, the inspection should also i verify that the foundation surface of cohesive soils has been i scarified or penetrated by tamping rollers to insure proper bonding of material. Any unacceptable surface material should be either removed or excavated and recompacted to design specifications.
?
4 j 4.2 Capillary Break (non-cohesive)
Capillary break materials should be inspected and tested to verify
- that the gradation requirements of the materials have been met.
t Testing of in-place capillary break materials should be accomplished l to assure that the in-place density of the materials is in conformance with the specified percentage of maximum relative
. density.
l 4.3 Geotextile Separators In some Remedial Action Plans, a geotextile separator may be specified for placement between two different construction materials. This separator should be inspected to verify that the s specified fabric is being used and that the fabric has no tears and has sufficient overlap of material between adjoining pieces when emplaced.
l 4.4 Seepsge Barrier / Liner (Cohesive) l Inspection and testing of seepage barrier / liner materials should include verification that gradation, classification, plasticity index, and the moisture-density relationship conform with the ,
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4.5 Tailings /Contaminntsd Material Inspection and testing of tailings / contaminated material should be accomplished to assure that the quantity and maximum size of foreign material placed in the encapsulation cell is in conformance with the applicable specifications. Compaction of tailings around the relatively large sized foreign material should meet the specified requirements. Inspection should also verify that organic materials
. are uniformly distributed throughout the emplaced tailings.
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Compaction testing should be accomplished to assure that the in-place density and moisture content of the emplaced tailings are ~
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j in compliance with applicable specifications.
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4.6 Radon Barrier / Soil Covers Materials for the radon barrier / soil cover should be inspected and i tested to ensure verification of gradation, plasticity index,
! classification, and moisture-density relationship to conform with
- the specifications. Testing of in-place density should also be j accomplished to ensure compliance with appropriate compaction specifications.
+
i 4.7 Filter Bed Inspection of filter bed materials emplacement should be accomplished to assure that they are being properly placed. Testing of emplaced materials should be accomplished to assure that the gradation is in conformance with applicable specifications.
Inspection should assure that the gradation of filter materials are not altered by segregation at the time of emplacement or by physical breakdown of grains by compaction equipment.
4.8 Riprap l' The placement of the riprap asterials should receive inspection to assure that proper placement techniques are employed to prevent ,
degradatica of the material due to improper handling, to assure that the distributien is uniform and that voids are kept as small as '
- possible, and to assure proper gradation. The inspection should alec verify that the size and classification of riprap rock, the litt thickness, and elevations comply with applicable specifications i and drawings. Inspection of riprap quality may be provided at the -*- - -
material source if required to assure compliance to the specification requirements. The testing should include durability i tests such as specific gravity, soundness, abrasion, and absorption.
Inspection of riprap at placement should include visual inspection
, of . size and shape of riprap asterials to ensure that riprap is nonsegregated (free of pockets of small stones or of clusters of large stones), that the gradation tolerance is met and that the riprap is not emplaced in layers.
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l 4.9 Top Soil If top soil is used over the riprap, the inspection should assure
[ that the loose thickness of the top soil conforms with the I specifications. The inspection and testing should also verify that l the lower layers of top soil are adequately compacted. The L inspection should further verify that the upper layers of the top i soil are seeded as per specificationsi i
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f 5 TESTING AND INSPECTION PROCEDURE
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5.1 Materials Certification t
, Materials which are supplied for installation or which require
, certification should be verified by the RAC's proj ect quality i department as having met the specified requirements. Appropriate tests should be run whenever there is a visible change in
', engineering characteristics of the material. The inspector should
} sign or initial the transmittal indicating acceptance or describing the reason (s) for non-acceptance.
t 5.2 Instrument Certification Instrumentation which is received should be inspected by the person responsible for using and maintaining the instrument. The instrument should be inspected for damage, for correct operation, and for proper calibration records. Equipment which does not meet the applicable requirements should not be used.
The calibration records should be included in the RAC's
, instruments calibration system. The system should identify the i
required frequency of calibration checks and methods of calibration for various instruments.
5.3 Compaction Evaluation Procedure
. Inspections and testing should assure that specified materials are c:r.placed and compacted as designated on drawings. The loose thickness of the lifts of material and elevationa should be verified frequently to ensure compliance to the specification requirements for the particular type of material emplaced. Inspection should also verify that the compaction equipment (or equivalent), as per ~~
specifications, is being used for compacting the material and the number of roller passes meets the specification requirements.
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In-place field dansity to::co cnd cufficient leboratory moicture-d:nsity tosto should be parforazd to furthsr cyclutte compretien.
However, the testing procedure should not jeopardize the integrity of the emplaced materials. The field density and moisture testing should be in accordance with ASTM D-698, ASTM D-1557, ASTM D-4253 and D-4254, ASTM D-1556 or ASTM D-2922, as applicable. The moisture content may also be determined by AASHTO T217 procedure, using the speedy moisture meter. However, when the speedy moisture tests are i
used, a correlation with oven drying method should be developed for each centh test. If it is necessary to calibrate the moisture meter af ter every tenth test, then more frequent correlations should be ,
obtained.
The field test frequency should be a minimum of one test per 1,000 I cubic yards of contaminated material placed and one test per 500 ,
, cubic yards of other compacted materials including seepage barrier l and/or radon barrier earth cover. There should be a minimum of two tests taken for each day that an appreciable amount of fill is I
placed (in excess of 150 cubic yards). There should be a minimum of one test per lift and at least one test for every full shif t of _
compaction operations.
i Prior to the start of field compaction operations, appropriate laboratory compaction curves should be obtained for the range of emplaced materials. During construction, one point Proctor tests at a frequency of one test for every five field density tests on cohesive materials should be performed. Similar checks should be provided for verifying relative densities of non-cohesive materials.
Supplementary laboratory compaction curves (based on complete Proctor tests) should be obtained, approximately one for every 10 or 15 field tests, depending on the variability of materials.
The field determination of moisture and density should be compared with the appropriate compaction curve to evaluate conformance with -
requirements. The Remedial Action Inspection Plan should include a criterion for evaluating the inspected field density and moisture j data based on a continuous review of data.
5.4 Grada, tion and Classification Testing i
The placement of materials should receive continuous inspection and frequent verification testing to asoure that specificatica requirements with respect ~ to gradation and classificatien are j maintained. The inspection should assure that the maximum particle l size in the emplaced material meets the specified requirements. For l all materials other than contaminated materials, at least one i gradation test should be run for each day of significant material -----z-1 placement (in excess of 150 cubic yards). Random samples obtained )
from material being placed should be used for these tests.
l Inspection may also be provided at the material source to assure l compliance with the specification requirements. Documentation of l
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the test results should be on appropriate laboratory test report i sheets and results of visual inspection should be documented in the daily inspection report.
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5.5 Atterberg Li=ito Tests Inspections should assure that the proper material is placed as designated on the drawings. Verification testing should include i determination of plasticity index, which determines the range of !
water content over which a cohesive soil behaves plastica 11y. The l tests should be run at least once for each day of significant cohesive cover or liner material placement (in excess of 150 cubic
- yards). The samples should be randomly selected. The test results r - - - --
- should be documented in the laboratory test reports. - ---
5.6 Rock Durability Tests For each gradation of riprap, rock durability tests such as specific gravity, absorption, sodium or magnesium sulfate soundness, and abrasion testing should be performed prior to delivery of any material to the site. The testing program may vary from site to site and is dependent on the type of rock selected and the expected environmental stresses that it will be subject to. During construction activities, additional test series should be performed for each type of riprap when approximately one-third and two-thirds of the total volume of each type of riprap have been delivered. For any type of riprap where the volume is greater than 30,000 cubic yards, a test series should be performed for each additional 10,000 cubic yards of riprap delivered. A final sample should be obtained .
for each riprap type following completion of delivery of the material.
5.7 Distribution of Organics Continuous visual observation during placement of organics in the encapsulation cell should be accomplished to assure that the organic material is uniform and evenly distributed. Also, the inspection should assure that the maximum size of the emplaced organic material does not exceed the specified requirements. Results of visual l inspection should be documented on the daily inspection report.
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6 NON-CONFORMANCES, CORRECTIVE ACTION AND STO? WORK ORDERS l
._ The Remedial Action Inspection Plan should establish procedurea to define, identify, and document non-conformances or deviations from I,
plans, specifications, or procedures. A mechanism to develop, :
control, approve and implement the necessary corrective action !
should also be established. Follow-up procedures to assure that proposed corrective -actions have . been implemented should be documented.
I The plan should also address provisions for a "Stop Work Order".
l The situations when a "Stop Work Order" may become necessary
- should be described. Procedures and level of authority for issuing l a "Stop Work Order" should be established and a mechanism for resolving the corresponding nonconformance(s) should be discussed.
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- - I 7 RECORDS Daily inspection reports should be written that address the adequacy, progress, and details of construction activities. The reports should include the results of visual inspection, measurements, and tests performed in the laboratory and in the ;
field. The inspection and test status should be identified by !
charts, as-builts, or by periodic status reports. The inspector should summarise volume of emplaced materials and the number of 4
field and laboratory tests performed on each material on a weekly _ _
appropriate to prevent inadvertently by-passing an inspection point. l The inspection and test reports should become part of the permanent j record of the implementation of the remedial action plan.
Test records should include date, name of tester or inspector, i items inspected or tested, type of inspection or test, identification of test method, results, acceptability and acceptance criteria, and name and initials of the reviewer. The records should also identify the testing equipment or instrument used in performing -
the test. When documenting deviations, nonconformances, and stop l t work order situations, the report should provide sufficient details so that acceptability of the necessary correctiva action and final ;
resolution can be independently reviewed. ,
8 CONCLUDING REMARKS This paper has identified remedial action inspection plan features related to geotechnical engineering that may be necessary to l control, verify, and document construction activities during .
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remedial action at inactive uranium will tailings sites. Since i conditions are likely to vary from site to site, the various remedial action inspection plans may differ in scope and extent. As seen from the discussion presented in the paper, most of the aspects '
of testing and inspection plans for these remedial actions are similar to those for the construction of other safety related earth structures. However, the following unique aspects of testing and ,
field inspection prgrams are associated with the inactive uranium .
mill tailings sites:
, (i)In most. cases, the inactive uranium mill tailings are located ;
in or are being relocated to remote areas. Also, unlike active tailfngs impoundments, the impounded waste has undergone significant
- drying and includes no free liquids. Therefore, it is expected that '
the consequences of an embankment failure under these conditions would not be as significant, with the possible exception of an ,
impoundment adjacent to a surface water feature The scope of the :
j construction and inspection testing program should be verablished recognizing the site specific variation in failure consequences.
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l (ii)An izportrat ecpact of th2 otability of thm tailings pilos is th2 matarin1'a vuln2r bility to liquafcetica and flow undsr sciccic conditions. Inactive tailings that are to be stabilized in place, are generally partially saturated and therefore, a total i liquefaction may not be possible. However, under vibratory l loading, significant flow of materials is possible due to localized liquefaction of the tailings or liquefaction of the subgrade. The earthwork operations intended to improve these aspects of the stability of the piles should generally receive considerable attention during inspection _ and testing of._the _ _ __ _ _ l remedial action activities. '
(iii)The remedial actions at inactive mill tailings impoundsents !
must be implemented so that the reclaimed sites meet appropriate EPA !
standards for the attenuation of radon release. Field control of cover materials, necessary to implement this aspect of the remedial j '
action, is substantially different from that required for the l construction control of many other earthwork projects.
(iv)The concern for the differential settlement of the remediated tailings is large because of the long time period (200-1000 years) of stability requirements with no reliance on routine maintenance during this period. Potential for development of cracks and/or preferential drainage pathways in the earth cover (radon barrier) '
resulting from differential settlement, and the resulting erosion are of major concern during testing and inspection of the remedial '
action. Likewise, the long-term stability requirements necessitate ,
greater concern for erosion protection durability than would t ,
normally be applied to other earthwork operations.
, In summary, construction of these remedial action plans must l assure adequacy of geotechnical stability, erosion protection, radon attention and protection against groundwater contamination. It is
- essential to assure that the specifications and design criteria for
- the remedial , actions are appropriate to meet the performance standerds, and that necessary and sufficient testing and inspection during construction are performed to verify that the remedial action program is properly implemented.
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BIBLIOGRAPHY Gupta Dinesh C., et.al., " Seismic Design Considerations for Uranium Mill Tailings Disposal Facilities," Seventh Annual Symposium on Management of Uranium Mill Tailings, Low-Level Waste, and Hazardous Waste, Colorado State University. Fort Collins, Colorado, February 6-8, 1985.
t Gillen Daniel M. , "Geotechnical Considerations in the NRC's Review
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of Uranium Mill Tailings Remedial Action Plans," Seventh Annual ---
Symposium on Management of Uranium Mill Tailings, Low-Level Waste, and Hazardous Waste, Colorado State University, Fort Collins, Colorado, February 6-8, 1985.
Kane J. D., " Design, Inspection and Regulation of Uranium Mill Tailings Retention Facilities," Proceedings of the 13th Annual Lecture Series of Geotechnical Group, Philadelphia Section of the ASCE on Geotechnics of Waste Management, July 1983.
U.S. Nuclear Regulatory Commission, " Design, Construction, and Inspection of Embankment Retention Systems for Uranium Mills,"
Regulatory Guide 3.11, Revision 2, 1977.
U.S. Nuclear Regulatory Commission, " Operation, Inspection and Surveillance of Embankment Retention Systems for Uranius Mill Tailings," Regulatory Guide 3.11.1, Revision 1 October 1980. ,
t Interagency Cozunittee on Dam Safety, Design Earthquake Task Group -
Subcermittee 1. " Proposed Federal Guidelines for Earthquake Analyses and Design of Dams," November 1984.
U,s. Nuclear Regulatory Commission, " Consolidation of Tailings,"
USNRC Report NUREG/CR-3204, October 1983.
U.S. Nuclear Regulatory Commission," Recommended Radiation Protection Practices for Low-Level Waste Disposal Sites," USNRC Report 'NUREG/
CR-3343, December 1983.
Code of Federal Regulations, 10 Part 40, Appendix A January 1984.
t U.S. Nuclear Regulatory Ccamission, Staff Technical Position on
" Testing and Itapection Plans during Construction of DOE's Remedial Action at inactive Uranium Mill Tailing Sites," September 1985.
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