ML20246H016

Std Format & Content for Documentation of Remedial Action Selection at Title I U Mill Tailings Sites, Staff Technical Position

ML20246H016
Person / Time
Issue date:	02/24/1989
From:	NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
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ML20246G944	List: ML20246G941 ML20246H016
References
REF-WM-39 NUDOCS 8903170432
Download: ML20246H016 (42)

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STAFF TECHNICAL POSITION STANDARD FORMAT AND CONTENT FOR DOCUMENTATION OF REMEDIAL ACTION SELECTION l

AT l TITLE I URAN!IJM MILL TAILINGS SITES l

FEBRUARY 24,1989 l

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DIVISION OF LOW-LEVEL MASTE MANAGEMENT AND DECOMMISSIONING OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS U. S. NUCLEAR REGULATORY COMMISSION ggo3170432 890315 WASTE PDC R, 9

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STAFF TECHNICAL' POSITION

-STANDARD FORMAT AND CONTENT FOR DOCUMENTATION OF REMEDIAL ACTION. SELECTION.

AT TITLE I URANIUM MILL TAILINGS SITES February 24, 1989 i ,

DIVISION OF LOW-LEVEL WASTE MANAGEMENT AND.0 COMMISSIONING OFFICE OF NUCLEAR MATERIAL SAFETY AND' SAFEGUARDS U.S. NUCLEAR REGULATORY COMMISSION l

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~ii TABLE OF CONTENTS

.Section- Pa!Le' INTRODUCTION..................................................... v'-

1 General Information........................................... 1 1.1. Site geography and demography..........................

.1-1.2. Summary of the proposed action...... .................. 1*

2 . Geologic stability.,........................................ .2:

2.1. Scope of work.......................................... 2 2.2. Regional. geology........'............................... 2-2.2.1. Regional physiography..~...................... 2

2. 2. 2. . Stratigraphic setting........................ 3 2.2.3. Structural setting............................ 3  ;

2.2.4. Seismotectonics.............................. 3 1 2.2.5. Resource development......................... 4 2.3. Site geology........................................... 4 .-

2.3.1. Bedrock geology.............................. 5 2.3.2. Surficial geology............................ 5 2.3.3. Geomorphology................................ 6 2.4. Geologic stability..................................... 7:

l' 2.4.1. Geomorphic stability......................... 7 2.4.2. Seismotectonic stability.................... 17 .;

i 2.5. Geologic suitability................................... 8 i l 3 Geotechnical stability...................................... 9 I

3.1 Site and material characterization..................... 9-3.1.1. Geotechnical investigations. . . . . . . . . . . . . . . . . . ' 9  ;

3.1.2. Testing program.................'............ 10  ;

3.1.3. Groundwater conditions...................... 10 l 3.1.4. S t r a t i g ra p hy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - ~J 3.2. Geotechnical engineering evaluation................... 10 i

3. 2.1. Slope stability............................. 11 3.2.2. Settlement.................................. 12 t

3.2.3. Lique faction po tential . . . . . . . . . . . . . . . . . . . . . . 13 3.2.4. Cover design................................ 13 3.3. Construction details.................................. 14 3.3.1. -Construction methods and features.. ......... 1<4 .

3.3.2. . Testing and inspection...................... 15 3 . 4 . S umma ry . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . .

15 l 4' Surface water hydrology and erosion protection. . . . . . . . . . . . . .16' i 4.1. Hydrologic description and conceptual design........... 16.

4. 2. F l oodi ng de te rmi nati o ns. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 4.2.1. P r e c i p i t a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L 17 f

4. 2. 2. Infiltration losses......................... 17 4.2.3. Time of concentration....................... 118 g

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. 4.' 2. 4. Rainfall. distributions...................... 18 4.2.5. Computation of the flood event.............. 18

4. 2. 5.1. Adj ace nt _ wa te rways . . . . . . . . . . . . . . . . . . . . . . 18 4.2.5.2. Onsite drainage......................... 19 4.3. Water surface profiles and channel velocities......... 19 l

4. 3.1. Adjacent waterways.......................... 19 1 4.3.2. Drainage ditches............................ 19-4.3.3. Top and sides of the embankment............. 20 l

4.4. Erosion protection design............................. 20 4.4.1.

4.4.2 Adj ac e n t wa te rway s . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Drainage ditches............................ 20' ];

4.4.3. Top 'and s ides of the embankment. . . . . . . . . . . . . 20

4. 5. Ro c k d u rab i l i ty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.6. QC (testing and inspection) for erosion protection.... 21 4.7. Upstream dam failures................................. 21 4.8. Summary..............................................., 21 5 Water resources protection................................. 22 5.1. Hydrogeologic characterization........................ 22 5.1.1. Identification of hydrogeologic units....... 22 5.1.2. Hydraulic and transport properties.......... 22 5.1. 3. Geochemical conditions...................... 23 5.1.4. Characterization methods.................... 23 5.1.5. Water-use................................... 23' 5.2. Conceptual design features for water resources protection............................................ 24 5.3. Disposal.............................................. 24

5. 3.1. Groundwater protection standard for disposa1...................................,c 24-5.3.1.1. Hazardous constituents.................. 24 5.3.1.2. Concentration limits.................... 25 1

5.3.1.3. Point of compliance..................... 25 5.3.2. Performance assessment...................... 25 5.3.3. Closure performance demonstration........... 25 5.3.4. Groundwater monitoring and corrective action p1an................................. 25 5.4. Groundwater cleanup.................................... 26-

5. 4.1. Groundwater cleanup standard................ 26' 5.4.1.1. Hazardous constituents.................. 26-5.4.1.2. Concentration limits.................... 27

5. 4. 2. Cl eanup demonstration. . . . . . . . . . . . . . . . . . . . . . . 27 5.4.3. Cleanup monitoring program.................. 27 5.5. Supplemental standards................................ 27 5 . 6 . S u mm a ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

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.6 Radon attenuation and site cleanup......................... 30'  ;

6.l. Radon attenuation...................................... 3 0 6.1.1 '. Selection of parameters..................... 30 6.1.2. Calculational methodology and design i

. results..................................... 130 1 6.2. Processing site cleanup............................... 31 6.2.1. Radiological site' characterization.......... 31 i 6. 2. 2. Standards used for cleanup. . . . . . . . . . . . . . . . . . 31 l- 6.2.3. Verification of cleanup ....................-31--

l 6 . 3 . S umm a ry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ' 3 2 APPENDIX A: References /Bibl iography. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 : l i

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INTRODUCTION Title I of the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA) provides for remediation of abandoned mill tailings sites and associated vicinity properties by the Department of_ Energy (DOE). UMTRCA requires, in part, that the remedial actions 'must be selected and performed by DOE in accordance with standards set by the U.S. Environmental Protection Agency (EPA) and with the concurrence of the Nuclear Regulatory. Commission (NRC).

Procedurally each selected remedial action is documented in a 00E Remedial Action Plan (RAP), and NRC's concurrence in that document constitutes concurrence with the selection of the planned remedial action.

In order for the NRC to concur in each selection of remedial action, certain technical findings must be made leading to conclusion that the remedial action is consistent with the governing EPA standards for stability, radon control, water resources protection, and site cleanup. This technical position, the l

" Standard Format and Content for Documentation of Remedial Action Selection at Title I Uranium Mill Tailings Sitos" (SF&C), describes the information needed for the NRC staff to reach this conclusion. Use of this guidance will help I ensure that documentation submitted by the DOE is complete and is directed I toward making the case that the remedial action meets the EPA standards.

Although the SF&C generally addresses the information needed for review, specific situations may require review of information that has not been itemized herein. On the other hand, since the SF&C is meant to cover a range <

of design conditions, some of the detailed information listed may not be I applicable to or appropriate for all sites.

The SF&C also establishes a standard format for presenting the information.

The NRC's concurrence document, the Technical Evaluation Report (TER), is divided into sections dealing with geologic stability, geotechnical stability, '

surface water hydrology and erosion protection, water resources protection, and radon attenuation and site cleanup. The SF&C consists of major sections which parallel the TER. Formatting the remedial action plan to match the TER will serve to facilitate the review / concurrence process by making it easier for reviewers to locate the information necessary for their specific review.

The DOE should prepare the remedial action plan in a manner that addresses each section and subsection discussed in the SF&C. Additional subheadings under the information areas addressed in the SF&C ran be added as DOE sees appropriate.

The information provided in the remedial action plan should be detailed enough for a reader to understand the proposed remedial action without referring to other volumes. Specific characterization data, laboratory test results, design calculations, technical analyses, or other details may be provided in appendices or supporting documents, and if so, should be explicitly

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vi-referenced in the appropriate section. If any of the information to be provided in a particular section is presented elsewhere in the remedial action ,

documentation, it .need not be repeated 'but' should also be explicitly cross-referenced. All references should be ' cited such that they direct the ,

reviewer to specific page numbers, tables, and/or - figures. In addition', each '

major section should include a summary of any items that need to be resolved- j prior to obtaining NRC concurrence, as .well as the strategy and schedule for

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.. l 1 GENERAL INFORMATION' In this section, the Department of Energy (D0E) should include information that

-is of interest to all reviewers regardless of technical discipline. Basic geographical: and demographical information establishing the setting for' the remedial action should be provided along with a brief summary of the existing-processing site conditions and the proposed remedial action.

1.1 Site Geography and Demography DOE should describe the processing site / disposal site location (s) by specifying the latitude and longitude as well as the State and county in which the site (s) is located. Nearby towns and cities should be identified, and the location of the site (s) relative to prominent features such as rivers and lakes should be 4 described. -Basic information should- also be provided that describes the j population distribution and any significant facilities or activities in the  !

vicinity of the disposal site.

1. 2 Summary of the Proposed Action DOE should describe the tailings piles, land, buildings,.etc. that comprise the existing processing site. An overview of the proposed remedial action shouid ..

be presented. The overview should include a description of 1) the type of remedial action, i.e. stabilization in place, stabilization on site, or relocation, 2) the method of material transportation, if relocation is proposed, 3) the size and configuration of the proposed disposal cell, 4) the layered features of the disposal cell, and 4) any additional key aspects of the remedial action. Drawings should be provided where appropriate.

The summary of the proposed action should also address each portion of the EPA standards and briefly discuss those aspects of the remedial action that will-ensure the standards are met.

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2 GE0 LOGIC STABILITY EPA standards listed in 40 CFR 192 (Ref. 1) do not include generic or site-specific requirements for the characterization of geological conditions at UMTRA Project sites. Rather, 40 CFR 192.02(a) requires control desi0ned to be ef fective for up to 1,000 years, to the extent achievable, and in any case for at least 200 years. NRC staff interpret this standard to mean certain geologic conditions must be met to have reasonable assurance that this long-term performance objective will be achieved. This chapter specifies the data and analyses we require to show a site has been adequately characterized and will meet remedial action standards. The level of detail of information provided should depend on the impact geologic conditions are likely to have on a site's stability.

2.1 Scope of Work DOE should describe the scope of work associated with geologic stability, including the types of geologic, geomorphic, and geophysical studies conducted to determine that the remedial action meets the EPA standard. These activities are not limited to geological field mapping and observations, but also include geotechnical testing and sampling, meteorological observation, and other activities providing basic earth sciences data. Previous work should be freely used and referenced as appropriate. The scope of work should conclude with a description of special site specific information, if any, which requires an unusual level of attention.

2.2 Regional Geology Regional geologic conditions must be briefly described in order to provide background for the detailed site characterization. Most of this information will be found in ordinary geological publications. This information most likely can be provided in tabular and graphic form, and lengthy text can be eliminated. In some places, however, regional geologic conditions may present serious concerns regarding disposal siting. These conditions require more rigorous characterization to show a site can meet EPA standards.

2.2.1 Regional Physiography DOE should identify the physiographic province and its subsection in which a site lies using Hunt's classification (Ref. 2), or a similar reference. The physiographic description should include general information including (1) the type of geomorphic surface which surrounds the site, such as flood plain, piedmont, etc., (2) the general relief and topography in the region, (3) the name, type, and extent of surface drainage systems of the region, and (4) the types and rates of major geomorphic processes.

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2.2.2 Stratigraphic Setting j q

Regional stratigraphy should be described' in sufficient detail to provide a j perspective of local geologic conditions at the proposed disposal site. Rock. ]

units at depths or distances beyond concern of the remedial action need not be- I treated in detail. Most of the regional _ stratigraphic information can probably a be portrayed on page-size geologic maps,. cross-sections, and stratigraphic- j columns. Detailed descriptions of units of specific interest to the remedial i action can be described in tabular form; including: (1) age, (2) name, (3) I thickness, (4) lithology and mineralogy, (5) induration, (6) relations to  !

adjacent units, and (7) geographic distribution. {

2.2.3 Stmetural Setting I Regional structural elements should be described in ' sufficient detail to l interpret specific structural features of._ the disposal site. Regional j

, structures can best be described with maps and cross sections showing basins j l and uplifts, folds, faults, lineaments, etc. The regional. structural. province a l

most closely associated with the site should be described in relation to the neighboring provinces, including rock types composing each element, thickness of rocks (e.g., basin fill), age of each structural element, and current structural stresses existing in the region. DOE should describe the general orientation and degroe of deformation of rocks which will become the tailings host or foundation.

2.2.4 Seismotectonics DOE should characterize the potential for tectonic activity in local and regional geologic structures that may contribute to earthquake generation and affect the suitability of the proposed disposal site and design. The charac- (

terization should include the following information: '

Seismicity The approach taken by DOE in describing potential ground motion at a site :i should begin with the historical seismicity of the region. A list should be provided of all recorded earthquakes that have occurred in the tectonic province of the site, or adjacent provinces within 200 km of the site, that could be expected to. influence local seismicity. The list should include dates, epicenter coordinates, ' depth of focus, origin time, intensity, and magnitude, and should be augmented by isoseismal maps showing locations and magnitudes of these earthquakes. This investigation should include any earthquakes that would help to~ identify the presence of-active geologic structures in the region or delineate the tectonic provinces of the region. Any earthquakes that induced geologic failures (e.g., landslides, liquefaction) should be indicated. An' acceptable source of earthquake information is the National Geophysical Data. Center.

All sources of information should be referenced.

4 Tectonics The structural geology of the region, especially in areas of low sei s n 'c i ty, should be described to identify potentially active geologic stri.; rures and aid in delineating tectonic provinces. The structural geology investigations may reveal disturbances caused by earthquakes prior to the historical period, which could help determine the activity of the geologic structures.

Tectonic provinces should be delineated, and the criteria for delineation should be civen. Evidence of tectonic activity which should be considered include e-Aift or subsidence and their rates, instrumented or historical seismicity, active fault traces, volcanism, lithospheric thinning, or elevated terrestrial' heat flow. If capable . faults are located in the vicinity of the site, a regional map showing their location and' characteristics should be presented.

Following these characterizations, a correlation. should be made between seismicity and geologic structures. In3 rationale for each correlation must be provided. If certain earthquakes sannot be correlated with geologic structures, their relationship to tectonic provinces should be discussed.

Information rec,ui rements for seismic risk analysis and determination of the design earthquake are discussed in Section 2.4.2 of this document.

2.2.5 Resource Development To assure that future resource development will not jeopardize success of the remedial action, DOE must characterize the occurrence of recoverable earth resources in the site area. Resources of concern are those which, if exploited, could result in inadvertent intrusion into the disposal site. An original exploration and resource evaluation program should not be necessary.

Rather, DOE should characterize " identified resources" as designated in U.S.

Geological Survey Circular 831 (Ref. 3). Identified resources include measured, indicated, and inferred resources whose location, grade, quality sad  ;

quantity are known or estimated from specific geological evidence. Geological '

evidence includes, but is not limited to, existing assays, geologic maps, geophysical and geochemical surveys, and core logs.

DOE should describe geologic resources occurring at or near the site.

Resources include metallic and nonmetallic minerals and ores; hydrocarbons such a's peat, lignite, coal, oil, gas, tar sands, and asphalt; geothermal resources; and industrial minerals such as sand and gravel, clay, shale, and building stone. Water resources should be characterized as described in Section 5.0 of l

this document.

l 2.3 Site Geology '

Bedrock conditions at tailings disposal sites are characterized primarily to provide basic information on ground-water geology and geotechnical stability.  !

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5 Conversely, surficidl geologic conditions are characterized to determine the geomorphic history and processes at the site, and assure that long-term stability standards will be met.

DOE should describe its findings with appropriate topographic maps, aerial photographs, cross sections and profiles, and scale drawings that exhibit geologic features pertinent to the disposal site and vicinity. Large-scale topographic maps should be prepared to display detailed features of the site, and to show how the remedial action design will relate to the underlying geologic units.

2.3.1 Bedrock Geology Bedrock at a proposed tailings disposal site must be characterized to show it provides a suitable foundation, exhibits suitable hydrostratigraphy, and contributes to long-term stability of the remedial action. DOE should describe in detail the lithologic, stratigraphic and structural properties of any rocks which will form the foundation of the tailings cell. In addition, data should be provided to show that the rocks are not subject to excessive erosional and seismic instability over the long term.

Most site specific data should be derived from original field observations made by DOE. The characterization should deal specifically with rocks which will form the tailings foundation or those which provide a source of usable ground water near the site, referring to information needs described in Sections 2.0 and 5.0 of this document. 00E should provide descriptions of bedrock features near the site including lithology (mineralogy, grain size, color, and cement),

stratigraphy, thickness, porosity, permeability, and degree of induration and weathering. The strike and dip of underlying formations should be reported along with observations of fractures, joints, faults, and other structural features. On a site-specific basis, DOE must determine to what level of detail each bedrock unit should be described, and provide a rationale far its characterization.

2.3.2 Surficial Geology Unconsolidated surficial deposits will likely be selected as a foundation and/or subgrade host for most tailings stabilization projects. In those cases, thorough characterization of surficial geology is of prime importance. Field and laboratory studies should be conducted using standard geological and geotechnical techniques for:

1) soil mapping .

2) geomorphic surface mapping

3) subsurface boring and trenching

4) soil and sediment sampling

5) sediment analysis

6) materials mechanical te: ting (see Section 3.0)

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Surficial geologic data should be reported here or included by reference to l another section of the remedial action documentation. . Mapping of soil and I geomorphic units following the North American Code of Stratigraphic Nomenclature should be provided. DOE'should provide detailed descriptions of Quaternary stratigraphy (including stratigraphic thickness and relations),

lithology (including grain-size distribution, mineralogy, color, porosity, 1 permeability, and cementation), source area and depositional environment, and i degree of weathering. Specific testing information may be found in References' )

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2.3.3 Geomorphology DOE must characterize the site geomorphic setting in order to confirm current J landscape stability and provide reasonable assurance that stability will. be '

maintained for the performance period required by the standards.

DOE should identify lower-order subdivisions of the physiographic province 'in j which the site lies. In addition, specific landforms which form the site and i its environs should be delineated and described. Typical landforms which I should be recognized are fluvial terraces or floodplains, alluvial fans, pediments, or piedmonts, and the stepped geomorphic surfaces these usually .

l include. Geomorphic surfaces should be identified and criteria for their )

recognition should be described, including: l l

1) height above modern base level

2) on-site relief '

3) surface morphology I a. surface gradients

b. small-scale geomorphic features

c. small-scale surficial relief I

4) associated deposits

5) soils (weathering profiles)

6) the local drainage basin 5

a. basin and sub-basin area

b. basin development

c. morphometry

d. basin hydrology

e. relations to regional drainage

7) channels

c. channel gradients

b. channel morphology and pattern

a. characteristics and recurrence of flow Finally, occurrence and rates of geomorphic processes which could' affect site stability should be examined. Geomorphic processes constitute two types of hazards to long-term tailings remediation: erosion and mass wasting. 'D0E should provide analyses of a' proposed disposal site which determine the genesis of the site's landforms and the procescn which are likely to take place in the future. Methods to recognize fluvial and colluvial landforms and evaluate

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7 geomorphic hazards may be found in Schumm and Chorley (Ref. 6). The methods used in DOE's analysis should be described or referenced.

2.4 Geologic Stability Local geologic conditions are likely to affect the geotechnical stability of the tailings pile, and the long-term stability of the landscape environment. A site's seismic risk should be analyzed as part of the geologic characterization, and the results should be applied to the geotechnical design.

Long-term site stability should be analyzed considering the characteristics of unconsolidated deposits and geomorphic processes at the site.

2.4.1 Geomorphic Stability l DOE must provide evidence that a proposed site has experienced long-term geomorphic stability, and that stable conditions will likely continue for the performance period of the remedial action. The evidence should be based upon l data and information discussed in Section 2.3 of this document.

To provide evidence of geomorphic stability, 00E should first establish the ages of geomorphic surfaces. These could result in relative, absolute, or semi qt.ontitative dates. Even though no specific standard exists, the NRC staff considers evidence of stability through Holocene time is reasonable and sufficient to document past long-term stability.

Next, geomorphic processes occurring over short and long time periods 'could influence tailings stabilization, and should be identified and quantified by 00E. Slope failures and extreme floods are the main catastrophic events which '

could occur over short time periods, but their potential should be analyzed in the geotechnical stability and surface-water hydrology sections of the remedial action documentation (see Sections 3.2.1 and 4.2 of this document). . Long-term geomorphic processes at the site should be analyzed by DOE, taking into account processes taking place now, changes in geomorphic processes, and impacts of humans. Site hazards should be recognized based on the geomorphic site l

characterization and by using check lists like those provided by Schumm and Chorley (Ref. 6). Specific calculations and projections should include scarp l retreat, overland soil erosion, channel growth, and channel migration. In i

addition, basin analysis should be completed to determine channel stability and the potential for entrenchment and gullying (Refs. 7, 8, and 9).

2.4.E Seismotectonic Stability DOE must provide disposal sites and des.igns that provide long-term stability during seismic events. The key to fulfilling this requirement is developing an understanding of the ground motion that can be anticipated at a site as a result of tnese seismic events.

Having catalogued the seismic activity, identified the significant geologic structures, and delineated the tectonic provinces (see hetion 2.2.4), DOE

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8 should provide an analysis of the seismicity and tectonics of the region surrounding the site to determine the source 'or sources generating ground motions that would most affect the stability of the site. Information should be provided that will enable the reviewer to determine that the following process has been appropriately applied. For each of the geologic structures that 00E has determined to be potentially active, the maximum credible -

earthquake that could be attributed to the structure should be calculated taking into account various parameters such as ruptura length, displacement, and mode of faulting. In areas where active geologic structures are not so l well-defined, DOE should use the historical' seismicity and other appropriate l evidence to define the maximum credible earthquakes for the delineated tectonic provinces.

Once maximum credible earthquakes have been determined' for each of the active I geologic structures and the tectonic provinces within 200 kilometers of the proposed site, 00E should use appropriate ground motion attenuation models. to calculate the levels of ground motion that would affect the site for each of. l these sources. For well-defined active geologic structures and for tectonic l provinces that do not contain the site, the ground motion should be determined  ;

assuming that an earthquake occurs at the closest approach of the structure or province to the site. For tectonic. provinces that contain the proposed site, the ground motion at the site should be calculated assuming the maximum

, credible earthquake for the province occurs 15 kilometers from the site.

i Ground motion at the site should be estimated using an attenuation relationship

! applicable to the site. Appropriate attenuation relationships for various parts of the United States can be found in References 10-14. Consideration l

should be made for mode of faulting or rupture directivity effects, if I

appropriate. Potential amplification of vibratory ground motion in unconsolidated deposits should also be addressed. '

l 2.5 Geologic Suitability If applicable, 00E should provide a concluding discussion of geological site conditions which present potential deficiencies in meeting requirements for long-term site stability. Potential deficiencies include substandard foundation materials, poor surface drainage, excessive seismicity or erosion, exceptional unexploited natural resources, or unpredictable volcanism or mass wasting. DOE's discussion should quantify the deficiency, and provide a scientific or design rationale showing the~ conditions will not ' violate standards. Due to the uncertainties involved, reliance on geologic conditions which require rigorous justifications should be minimized.

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3 GE0 TECHNICAL ~ STABILITY The proposed remedial action must meet the EPA standard that control of. the tailings be effective for 1000 years to the extent reasonably achievable and,,

in any case, for at least 200 years. For 00E to demonstrate this, .the documentation supporting the plans for remedial action must, in part,.contain geotechnical information and design details related to the disposal site and all materials associated with the remedial action design including foundation-and excavation materials, contaminated materials, and cover materials.

3.1 Site and Naterial Characterization Information should be presented that thoroughly defines the conditions . and engineering properties of all soil and rock materials that- could affect .the ~

performance of the proposed disposal cell, or that will be incorporated into <

the disposal cell. Information on the geotechnical characteristics of the site and materials should include (1) the scope and. results of geologic and geotechnical investigations conducted at the processing site, the disposal site, and the borrow areas, (2) the scope and results of field and laboratory l tests conducted to . determine ~ the engineering properties of .the subsurface, contaminated, and borrow materials, (3) the groundwater. conditions at the disposal site as they relate to the geotechnical design, and (4) interpretation-of the disposal site stratigraphy. If any of the information relevant to the geotechnical characteristics of the site and materials is presented elsewhere

-in the remedial action documentation, such information need not be repeated ,

l here but should be explicitly cross referenced.

3.1.1 Geotechnical Investigations The scope and results of the geotechnical investigations performed to define the. occurrence and properties of the underlying materials at the disposal site .

and the borrow areas, and the contaminated ' materials at the processing site should be presented. Reference 16 can be used as general guidance -for

, developing investigation programs and for conducting' subsurface investigations.

Information pertinent to the investigations should include the following:

(a) a plot plan (s) clearly showing the outline of the disposal site, disposal cell, processing site, and borrow. areas, and the locations of all borings, probes, pits, trenches, seismic lines, piezometers, and stratigraphic cross sections; 1

(b) detailed final logs of borings, probes, pits, trenches, and geophysical investigations; and.

(c) a summary presentation of the scope of the investigations.

completed and an assessment of why it is adequate to.

characterize the disposal site, contaminated materials, and borrow materials.

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, i 10 3.1.2 Testing Program ,

The testing program should be consistent with the needs of the proposed- l remedial action and demonstration that the design will meet the long-term j stability standards. Test methods should be appropriately referenced, or ]

described in detail where unusual conditions or deviations from standard j practice exist. Summary tables and plots should be provided which catalog the l important test results. The discussion should include or reference the criteria used to determine that the samples were properly taken and were tested "

in sufficient number to adequately define all the necessary soil and rock parameters. j Regulatory Guide 1.138 (Ref.17) can be used as general guidance for conducting a laboratory testing program to identify and classify soils and rocks and to evaluate their physical and engineering properties.  ;

I 3.1.3 Groundwater Conditions  !

1 The scope and format for the information to be submitted on the groundwater conditions at the site are generally given in Section 5.1 of this document. 3 l

However, the following specific information is required under this section:

(a) the location of the groundwater table and the anticipated elevation range of temporal fluctuations in the groundwater level based on recorded field data; I (b) the presence of perched, aquifer or artesian conditions; and (c) Discussion of potential water levels resulting from the occurrence of design basis events (e.g. the PMF).

3.1.4 Stratigraphy Based on the investigation program, the documentation should include stratigraphic profiles and cross sections of the tailings and the disposal site illustrating the detailed relationship of the proposed remedial action to the subsurface materials. The cross sections should show the location and results of borings or other exploratory methods from which the information in the cross sections is derived.

3.2 Geotechnical Engineering Evaluation The geotechnical engineering evaluation should include information and analyses pertinent to the demonstration that the proposed design will resist certain conditions potentially disruptive of long-term stability, such as slope failure, excessive settlement, liquefaction, and cover cracking. These analyses should take into consideration the design-basis events, i.e. design earthquake (see section 2.1.4), design flood (see section 4.2.5), and extreme meteorological conditions.

,.t 11 The methods of analyses should be identified in this section of. the main '

document, but further description of the methods and details of the analyses- i may be presented in an appendix or in supporting documents. If. a detailed description ~ of any method of analysis is presented in a reference document readily available to the NRC staff, then an explicit reference to that in lieu g of a detailed description will suffice. If'any of the information pertinent to the geotechnical evaluation is presented in other sections of the remedial-

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action selection documentation, it does not have to .be repeated- here, but the .l appropriate sections should be explicitly referenced. ,

3.2.1 Slope Stability The slope stability analysis should be such that it sufficiently demonstrates,- I l

for both static and dynamic conditions, the stability o_f the slopes .of the l remedial action embankment and any other slope at the site whose failure could- l adversely affect the remedial action. The presentation of the' analysis should include:

1 (a) Locations Selected-for Analysis -' Cross sections 'and profiles of the slopes should be provided in sufficient number and.

detail to represent all significant slope, foundation, ' and groundwater conditions. The. results . of subsurface explorations and -field and laboratory.. testing . should be reflected on the developed. sections and. profiles. .The sections selected for slope stability analysis should be described including the basis for selection (e.g. , at the location of maximum slope height or where weak.. foundation or l

in situ material is present).

l (b) Adopted Design Properties - A summary and description' of properties of the soil and rock comprising the slopes, and a discussion of the procedures used to estimate, from the available field and- laboratory data, conservative ~ soil l properties and profiles to be used in the analysis should be.

provided. The adopted design properties -for fill materials need to be consistent with the compaction controls'(density j and moisture) to be specified in construction.

(c) Methods of Analysis - The methods of stability analysis (e.g., circular arc or wedge) need to be identified.

Further, the selection by the designer from the. variations that are possible with a given method needs' to be described (e.g. -the imposition and direction of . side earth forces on the side. of a circular arc. slice). Seepage and loading conditions that could reasonably be' anticipated to occur during the long-term period that stability is ~ to be assured.

should be described and analyzed.

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(d) Results of Analysis - The results of the slope stability study should be summarized in graphic and tabular form and should clearly identify j the sliding surfaces correlated with resulting factors of safety and i the loading cases that were analyzed. At least one manual l calculational check should be provided for each method of analysis j that was performed using a computer code. The manual check should be  !

at an important location where the lowest margin of safety against lt failure had been indicated in the computer solution. Computer programs, other than those that are commercially available and commonly accepted, need to be described and validated.  ;

3.2.2 Settlement The settlement analysis should demonstrate that the estimated settlements, especially differential settlement, will not lead to disruptive conditions such {

as surface water flow concentration or cracking of the radon barrier cover j materials.  ;

The presentation of the analysis should include the following information: I (a) Locations Selected for Analysis - A description of the j locations selected for the analysis of settlement and the basis for the selection should be provided. This should {

include the best, average, and worst conditions regarding settlement at the site to enable an evaluation of the range of total and differential settlements at the selected locations. Cross sections and profiles should be provided l with the results of subsurface explorations (material types and layer thicknesses), fill placement, subsurface water elevations, and surface drainage features (as they may affect settlements) superimposed.  ;

(b) Engineering Properties - A description and the results of testing conducted to establish soil engineering properties (e.g., compressibility characteristics) needed in the  !

settlement analysis, including summary tables and graphs,  !

should be provided. The soil parameters selected for input  !

into the settlement analysis should be identified and the l technical basis for their selection should be given.

(c) Methods for Estimating Settlements - The methods used to calculate the amounts (immediate, primary, total and l differential) and the time rates of settlement should be  ;

described or referenced. )

l (d) Results of Settlement Analysis -

The results of the 1

! settlement study should be described and summarized in 1 tabular or graphical form. The results should identify 1 settlements estimated to occur before and after placement of ,

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4 13 the radon barrier materials and the time periods estimated for 'these settlements to occur. At least one manual check of computerized solutions should be provided. ' Computer programs, other than those that are commercially available and commonly accepted, should be described and validated.

(e) Evaluation of Settlement Estimates - The significance of' the settlement estimates should be discussed and assessed. l Analysis indicating that settlements are unacceptably high or '

that time for consolidation is ' excessively long, to where detrimental effects on the radon' barrier cover could occur, l should logically. lead to considerations for redesign or remedial measures.

1 (f) Settlement Monitoring - A description of any plan to monitor I settlements during and -following construction should be-provided including drawings showing typical details of the 1 monitoring installations and locations. The settlement monitoring plan.should describe the provisions for comparing I actual amounts and time of. settlements with predicted values. I 3.2.3 Liquefaction Potential If the embankment (disposal cell) or foundation materials at the disposal site are saturated, loose, cohesionless soils, then an analysis of the liquefaction:

potential of these materials is necessary for long-term stability considerations. The analysis should include the following:

(a) A description of the method of analysis selected and the basis for its selection. The need for a detailed liquefaction analysis should be determined on a ' case-by-case basis and should consider the level of earthquake shaking, site stratigraphy, critical so;l parameters,. and the consequences of a liquefaction-induced failure; (b) A discussion of the appropriateness of the soil parameters used in the analysis; (c) A presentation of the results of the analysis (including 1 margins of safety) and a discussion of its physical significance in the context of the method of analysis used.

3.2.4 Cover Design .

l Information should be provided in the remedial action plan and I

appendices / supporting documents that describes the cover's ability to perform for the required period of time, to resist degradation, to minimize infiltration and to minimize the effects of differential settlements. The l

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'cov'er's ability to perform as a radon barrier is1 discussed in_ Section 6.1. The' information to be. provided should -include: 1) a; detailed. description of the-cover material types (e.g. Unified ' Soil Classification System) or. soil mixture

. (e.g. ,- bentonite additive) and the - basis - for. their selection; 2). a ' schematic .

drawing displaying the variousilayers and thicknesses that comprise theJcover design; 3) a: description of the applicable field and laboratorysinvestigations and testing 'that were completed and .identifi. cation of the material properties (permeabil.ity, moisture-density relationships, gradation,- shrinkage . and

'dispersfyi6 characteristics, resistance.to freeze-thaw degradation, and chemical compatibility); 4) details including sketches' of. the cover terminationDat boundariest with ' any considerations for safely accommodating f subsurface ' waterJ L

l flows; and 5) a description (with- sketches) of any-. penetration (e .'g. ,

l monitoring _well) through the cover system including details .for sealing loff- and maintaining cover integrity.-

If low permeability membranes (geomembranes) are_ proposed as .part of a cover system design, the membranes _ need to be adequately described <and' their major properties (e.g., physical - and mechanical) provided. .The. methods for.

. installing _ the . membranes. in accordance with the manufacturers s recommendations also need to be discussed. Because of the lack of long-term performance and -

survivability records for polymeric membranes, ' their f use alone, to satisfy design and regulatory requirements for the cover system, is notirecommended.

3.3 Construction Details

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In addition to the geotechnic'al consideration and' design linformation discussed in the previous sections, the remedial action documentation should ' include information which detail's the construction features,: methods, :and verification testing. This information is necessary to demonstrate .' that ' the' selected remedial action will be carried out in the field in such 'a- manner that :the performed remedial action meets the EPA standards.

3.3.1 Construction Methods and Features

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The information to be provided in_ this section ~ should include site. plans and engineering drawings that clearly convey .the remedial action design features.

The engineering drawings should -show dimensions, . sections, and . relative.

locations of the tailings disposal ' cell and any other_ facilities within the site - boundary. A sequential- description of-the construction operations.~should also be provided.

Construction . specifications should be included .in thisl section, but 'need only.

be ' those specifications that deal with; the1 aspects? of. the ~ remedial action -

directly related 'to meeting the - EPA standards. = For example',1 specification sections such as mobilization, meast.Nment 'and payment, road signs', and chain.

link fence and gates that are~ generally includedHin the subcontract documents package ~need not be provided. However, those specifications - that deallwith

. excavation, material placement procedures, material requirements, L compaction .

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• control, etc. should be included. Reference to .the entire s et -. ~ of specifications provided as a supporting document is also acceptable.

3.3.2 Testing and Inspection This section should include descriptions of the methc,ds , procedures and-frequencies by which the construction materials and activities are to be tested and inspected to verify compliance with the design. specification requirements.

In general, this section will be comprised of the information ' that has previously been included in the site specific Remedial Action Inspection D]ang (RAIPs). The NRC technical position on testing and inspection (Reference 18). 1 should be considered in the preparation of this description.

3.4 Summary l_ This section should present a short summary of the results of the geotechnical' engineering and construction evaluations and the conclusions regarding .the ability of the proposed remedial action to meet the applicable EPA standards.

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16 4 SURFACE WATER HYDROLOGY AND EROSION PROTECTION The EPA Standards promulgated in 40 CFR Part 192, Subpart A require that the control of tailings should be effective for up to 1000 years, to the extent reasonably achievable, and in any case, for at least 200 years. The NRC staff has interpreted this to mean that the tailings should be isolated from contact with the surrounding environment.

The following sections address the surface water hydrology and erosion protection information, data and analyses necessary to demonstrate compliance with there requirements. The data and analyses should be sufficient and complete in both scope and detail to allow an independent evaluation of the adequacy of the stabilization design.

4.1 Hydrologic Descriptions and Conceptual Design DOE should provide sufficient graphical and quantitative data and information to fully characterize site drainage, surrounding watersheds, and fluvial features. Aspects of the conceptual design potentially impacted by, or directly mitigating the effects of surface erosion (for example, erosion protection for diversion channels and soil covers) should be described in sufficient detail to allow independent evaluations to be made. The types of information and data needed include:

o Topographic maps of sufficiently good quality and clarity (legibility) to allow analysis of pre- and post-construction drainage patterns, o Hydrography and stream flow records from other agencies; USGS, SCS, NOAA, COE, and State and river basin agencies, if available, and if used to justify the selection of a design flood event.

o Descriptions of existing and proposed reservoirs and dams (both upstream and downstream) which could affect the disposal site.

o Tabulations of drainage areas, types of structures, appurtenances, seismic and spillway design criteria, elevation-storage relationships, and short- and long-term storage allocations of dams and reserviors, o History of precipitation and flooding events in the disposal site area.

o Size and configuration of upstream drainage areas, including data on important tributaries.

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o. Erosion protection design features, such as diversion '

channels, rock aprons, toe reinforcements, riprap rock armoring of slopes and revegetation strategies.

o Cross sectional drawings indicating the proposed location of the tailings and the cover as related to streams, drainage channels, erosion protection, and other hydraulic features.

o Descriptions of the surrounding environment; such as the naturally occurring . soil slope (s), gully sizes and depths, vegetation density, and geomorphological features.

Information which is submitted by DOE on erosion protection should be complete, l clear, legible (maps should not be too small to read or make out features) and i should be in sufficient detail to allow an independent evaluation to be made.

This section should also consist of a brief narrative describing 'the remedial' action with specific attention devoted to the surface water erosion aspects of-the design. Specific data related to erosion protection ' analyses and design 1

features may be cross-referenced to other sections of the document. 1 1

4.2 Flooding Determinations DOE should provide data, information and anal.yses used in ' evaluating the capability of the disposal site to withstand precipitation ' events up to and including the Probable Maximum Precipitation (PMP)' and flood events up to and including the Probable Maximum Flood (PMF). Should DOE select lesser events than the PMP or PMF, DOE should also provide additional justification supporting the alternate design basis' capacity to meet the EPA longevity .!.

criteria (40 CFR Part 192,-Subpart A).  !

Specifically, DOE should provide estimates of rainfall intensity, infiltration losses, times of concentrations, rainfall distributions, peak flood flows, depths and distribution of flow, as well as flow velocities, and hydrography.

Again, this information and data should be sufficiently detailed to allow an j independent evaluation to be made.

A 4.2.1 Precipitation

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DOE should provide information and data used in the determination of the 1 maximum precipitation intensity and the magnitude .of the design precipitation il event. Calculations of total rainfall depth and methods of computation should be included. Where the design-flood event corresponds to a precipitation less.

than the PMP, a range of precipitation events should be considered and justified to satisfy the EPA Standards.

4.2.2 Infiltration Losses i

If infiltration is assumed to occur in any flood analysis, DOE should provide i estimates and bases for the soil infiltration rate, the soil type and runoff

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18' potential, the watershed area over which losses occur,- the average slope (s), '

the elevation differences, the length of the watercourse, . the type and amount -

of cover, and the antecedent moisture conditions. If DOE makes an assumption-that no infiltration will occur (cons'ervative with respect to erosion protection design), these analyse's and justifications are not needed.

4.2.3 Time of Concentration DOE should provide estimates for the time of concentration (tc) for a particular drainage basin using the most appropriate method for that basin. I f-the peak flood computations are sensitive to the tc estimate,.various estimates jl using different methods of computing tc should be presented. DOE should l present the various methods used, and include calculations and justifications j for all assumptions. a l

4.2.4 Rainfall Distributions DOE should provide information and data related to the development of peak flood estimates. These estimates should include . consideration of various -

critical rainfall distribution patterns and intensities. The amount of information needed will vary according to the size and comple.xity of the drainage basin. For very small drainage areas with simple shapes and configurations, DOE should provide calculations used in estimating rainfall intensity for the development of peak f' cod discharges; for larger and more complex basins, it may be necessary to provide detailed information related to rainfall distributions as they vary temporally and spatially over a basin.

4.2.5 Computation of the Flood Event Depending on the size and complexity of the drainage basin, differing degrees of information and documentation are needed. In general, larger offsite l streams will require more information and analysis than smaller basins which exist onsite.

4.2.5.1 Adjacent Waterways. .{

DOE should provide estimates of the peak flood rates from nearby waterways ,

using methodologies consistent with the type of the waterway, since the  !

elevation and velocity attained by flooding on a large adjacent stream may 1 establish the required protection level for a reclaimed impoundment.

DOE should provide computer printouts (if available) of the results and methods j used (such as the U. S. Army Corps of Engineers HEC-1). DOE shouldl also I present comparisons of the computed flood peaks with historical peak flood -

discharge data (such as those data found in Reference 19). - DOE should also present comparisons of the computed flood peaks with past flood peaks (elevation and velocity), which may provide additional evidence for the appropriateness of the estimated peak flood flow.

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4.2.5.2 Onsite Drainage l

DOE should provide information which addresses the effects of onsite flooding on the stabilized pile. Peak flow rates which are used to design features such l as erosion protection for diversion channels and aprons (which are configured so as to protect the stabilized pile from the erosive velocities at critical 1 points) should be provided. DOE should present the calculations, computational 6 methods, analyses, and assumptions which were used to determine peak flow rates I for these design features. DOE should also provide information and $

calculations which address the computation of peak flow rates used to design .f the erosion protection for the top and sides of the pile. .{

4.3 Water Surface Profiles and Channel Velocities.

Depending on the complexity of the waterway or channel, DOE should provide the i results of computations of water surface profiles, velocities, and shear i stresses used in designing erosion protection features. J l 4.3.1 Adjacent Waterways q

l l DOE should provide the results (e.g., computer printouts) of ~ water surface l profile calculations (such as HEC-2) for any nearby streams, rivers, or i l reservoirs. DOE should describe the maximum water level, velocity, and shear '

stress associated with the design flood event. DOE should also provide j' information and analyses regarding potential irregularities (such as bends) in 1 l

stream channels which can cause localized increases in shear forces and should  !

delineate those areas where hydraulic jumps, eddies, or vortices could occur.' j These forces should be characterized and considered in the size, thickness, and l placement of the erosion protection.

4.3.2 Drainage Ditches As previously discussed in Section 4.2.5.2, water surface profiles, peak flow velocities, and the resultant shear stresses should be characterized in order to datermine the adequacy of the erosion protection for any drainage or diversion ditches. For uniform channels of constant shape, normal depth, and normal velocity, calculations should be provided. For more complex drainage ditches, DOE should provide information such as that referred to in Section 4.3.1.

The design of the side slopes of the ditches to resist perpendicular flow velocities resulting from inflow from natural gullies (as well as longitudinal flow velocities) should be described. In addition, DOE should describe the

, potential for clogging and sedimentation of the ditches and any design features (such as steeper slopes) which are utilized to mitigate the effects of clogging and sedimentation. DOE should provide the calculations which were used ..in these analyses.

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l 20 4.3.3 Top and Sides of the Embankment q

DOE should provide the peak flow rates, velocities, and shear. stresses used in-the development of erosion protection designs for .the top and side slopes' of the pile. 00E should present the models, analyses, assumptions, and all-calculations used in the peak flow rate determinations.

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4.4 Erosion Protection Design In general, -different models and techniques are used to design. erosion )

protection depending on its location relative to the pile. l 4.4.1 Adjacent Waterways i

l DOE should present the methods, analyses, and assumptions used to design l erosion protection along adjacent stream banks to prevent erosion or encroachment into the tailings area. Information regarding input parameters to computational . methods (such as the Safety Factors Method) should be provided.

Geomorphic processes such as stream avulsion or meander cutoffs should be discussed, also, if such phenomena could have an impact on the design of the j erosion protection.

4.4.2 Drainage Ditches In addition to information discussed in Section 4.4.1'above, DOE should provide

, information related to design of drainage ditch outlets where they transition l into natural gullies or flow onto natural ground. DOE should present the ]

results of analyses and calculations which document the design of erosion l protection at these locations.

l 4.4.3 Top and Sides of the Embankment DOE should provide the results of various methods used to ' determine erosion protection requirements for the top slopes (such as the Safety Factors Method) and the side slopes (such as the Stephensen Method). DOE should present the calculations, methods, analyses, and input parameters used in the computational models.

4.5 Rock Durability DOE should provide the results of rock durability testing and gredation testing which demonstrates that the rock will survive weathering over the design period. Should the rock source be of . marginal quality or mixed with less-

~

suitable rock, approaches such as oversizing and increasing the thickness and l volume should be described or referenced. Methods, bases, and calculations

) used for such oversizing and overthickening should also be' provided and discussed.

_ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ = _ _ _ - - _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ -

21 4.6 Quality Control (testing and inspection) for Erosion Protection DOE should present the site-specific programs for testing and inspection of the-erosion protection. DOE should describe or reference the testing programs for .;

verifying rock quality, rock gradation, rock placement, and other aspects of l the erosion protection design. l l

4.7 Upstream Dam Failures

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DOE should document the existence, location and sizes of upstream dams or other surface water impoundments. DOE should provide the results of dam failure analyses documenting whether a dam failure is or is' not the controlling design basis event. If dam failures establish the controlling flood level and 3 l . velocity, information similar to that given in Section-4.2 should be provided. J 4.8 Summary In the summary, DOE should focus on the various considerations discussed previously, discussing how the control and longevity standards in -40 CFR Part 192, Subpart A are met by the proposed erosion protection design. Any outstanding issues should be' itemized, along with DOE's plan of action to resolve them.

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5 WATER RESOURCES PROTECTION 00E should provide a demonstration of compliance with the U.S. Environmental Protection Agency (EPA) standards for groundwater _ protection at inactive uranium mill tailings sites in Subparts A-C of 40 CFR Part 192. The introduction to the Water Resources Protection Section should clearly outline l DOE's strategy for compliance with these standards. For example, the j introduction should summarize the groundwater protection and cleanup standards and the principal elements in DOE's compliance demonstration. After the introduction, DOE should describe the hydrogeologic setting and features'of the proposed design contributing to compliance with the standard. This information supports the more detailed description of compliance with the ' groundwater protection and cleanup standards in 40 CFR Part 192. All information used to {

demonstrate compliance with the standards should be sufficiently complete 'to 1 allow an independent evaluation of compliance with the EPA standards to be I made. More detailed discussion on the compliance demonstration can be found in Reference 20.

5.1 Hydrogeologic Characterization To fully characterize the hydrogeology associated with each remedial action, DOE should provide descriptions of the hydrogeologic - units at both the 1 processing site and the disposal site, the methods used to characterize those units, and the water usage in the vicinity of the sites. Descriptions of the hydrogeology should make use of hydrogeologic cross-sections and maps, including the information identified 'under items 1 and 3.1 of' Table 4.1 in Reference 2.

5.1.1 Identification of Hydrogeologic Units DOE should describe the hydrogeology of both the' processing site and the disposal site. Information on all potentially affected aquifers and confining units should be provided, including their geometry, lateral extent, thickness, recharge and discharge zones, and flow characteristics '(fracture flow vs.

porous media flow). Descriptions should also identify unsaturated hydrogeologic units that may convey hazardous. constituents released from residual radioactive material. Sufficient graphical and quantitative data and information should be presented to provide a range of defensible conceptual hydrogeologic models.

5.1. 2 Hydraulic and Transport Properties DOE should describe the hydraulic and transport properties of all potentially affected hydrogeologic units at both the processing site and the disposal site.

Hydraulic and transport properties include hydraulic conductivities, storage characteristics (specific yield or storativity), effective porosities, and dispersivities. DOE should also describe hydraulic gradients, groundwater. flow directions, and groundwater velocities (average linear velocities) for each potentially affected hydrogeologic unit. These descriptions should consider

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23 the spatial and temporal distribution and isotropy of these properties as )

appropriate to support compliance demonstrations. The properties should be based on an appropriate combination of field data that are demonstrably representative of the hydrogeologic system.

5.1.3 Geochemical Conditions l

DOE should provide descriptions of the water quality of all potentially -

affected aquifers at both the processing site and the disposal site, including background concentrations of selected radionuclides and other organic and inorganic constituents. This information should include field data on pH, redox potential, alkalinity, temperature, and specific conductance. All water quality data should be accompanied with sufficient information to demonstrate the reliability of the data, including . ion balances, comparisons of total dissolved solids concentrations with the sums of measured constituent concentrations, and other indicators as appropriate. Geochemical descriptions should also provide sufficient information to characterize potential source (s) of contamination and geochemical conditions that effect attenuation of hazardous constituent transport. Source descriptions should include i evaluations of the physical and chemical characteristics that influence the  ;

long-term leaching and release of hazardous constituents, such as grain size, I hydraulic properties, solid phases, solid composition, pH, Eh, and leaching data. To support geochemical attenuation demonstrations, geochemical descriptions should include information on solid composition, buffering capacity, redox potential, sorption coefficients, and other qualitative and l quantitative information as appropriate.

5.1.4 Characterization Methods DOE should describe all characterization activities, methods, and monitoring  !

installations sufficiently to demonstrate that the site characterization l information adequately supports a representative and defensible hydrogeologic  !

conceptual model or sets of models. Monitoring well descriptions, for example, should include location, elevation, screened intervals, depths, construction and completion details, and hydrogeologic units monitored. Aquifer test <

descriptions should include testing configuration, test results, and a '

l discussion of the assumptions, analytical techniques, test procedures, l limitations and results. Descriptions of water quality sampling programs should describe or reference procedures for sampling, preserving, storing, and analyzing samples, including Quality Assurance and Quality Control protocols.

l Method descriptions should demonstrate consistency, as appropriate, with current standard methods and practices.

5.1.5 Water Use 00E should describe existing and potential future water uses in the vicinity of l the disposal and processing sites. Such descriptions should include water j quality characteristics, availability and characteristics of alternative water '

sources, and institutional controls on water use. The description should also

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.i 24 provide an inventory of all existing and planned surface and grouncl water uses I that could be affected by existing groundwater contamination, cleanup activities, or potential contamination from the disposal unit. Surveys used to prepare the inventory should consider an area large enough to characteri.te ,

water use in the vicinity of the site, which is typically enclosed within a '

one- to two-mile radius of the site. The inventory should document the owner; l location; type and amount of use; source of supply; type of intake (for surface j water users); well depth, screened interval, and hydrogeologic units (for l groundwater users); and water quality.

5.2 Conceptual Design Features for Water Resources Protection DOE should describe the principal design features of the proposed remediated tailings pile that are relied upon to demonstrate compliance with the j groundwater aspects of the EPA standards. For each design feature, DOE should identify the purpose of the feature, describe the feature using appropriate drawings, provide material and construction specifications, demonstrate 4 acceptable performance using appropriate calculations and test data, and demonstrate that the feature does not rely on active maintenance to ensure adequate long-term performance. For example, earthen cover descriptions should demonstrate that the covers have been . designed to minimize infiltration .of water into residual radioactive materials, provide plans and cross-sections depicting cover construction, identify minimum material and construction specifications to attain compliance, and demonstrate that the cover does not rely on active maintenance to assure acceptable performance.

5.3 Disposal In this section, DOE should demonstrate that the proposed disposal design complies with EPA's groundwater protection standards in 40 CFR Part 192, Subparts A and C. Such demonstrations consist of the following components: 1) the groundwater protection standard, 2) a performance assessment, 3) a closure performance demonstration, and 4) a performance monitoring and corrective action program. A more detailed discussion of that demonstration can be found in Reference 20. The following sections summarize the information that should be contained in DOE compliance demonstrations.

5.3.1 Groundwater Protection Standard for Disposal DOE should propose a groundwater protection standard for the disposal site.

The groundwater protection standard for disposal consists of three components:

1) a list of hazardous constituents, 2) a corresponding list of concentration limits for the constituents, and 3) a point of compliance.

5.3.1.1 Hazardous Constituents DOE should provide a list of hazardous constituents that are likely to be in or be derived from the residual radioactive material at the disposal site. DOE should justifiy its list based on characterization of the composition of

o 25 residual radioactive material, groundwater quality data, description of the processes and reagents used in processing uranium, and assessment of whether constituents are reasonably expected to be in or derived from the residual radioactive material.

5.3.1.2 Concentration Limits DOE should propose a concentration limit for each hazardous constituent identified above. The concentration limit will be either the background concentration of the constituent, the Maimum Constituent Level identified in Table 1 of 40 CFR Part 264.94, as modified by 40 CFR Part 192.02(a)(ii), or an alternate concentration limit (ACL). In addition to providing a proposed limit for each constituent, DOE should provide the justification for its selection of background limits or ACL's as discussed in Section 2.1.2 of Reference 20.

5.3.1.3 Point of Compliance j 00E should propose the point of compliance for the disposal site. The proposed puint of compliance (actually a vertical surface) should be identified on an l appropriate map. DOE should demonstrate that the point of compliance is as l close to the disposal area as practical, that it provides access for monitoring l

! groundwater quality without disturbing the pile, and that groundwater j

! monitoring at the proposed location will provide early warning of release of hazardous constituents. I i

5. 3. 2 Performance Assessment 1

DOE should demonstate that the performance of the disposal unit will comply I with the groundwater protection standard for disposal. Using quantitative analyses of infiltration, leaching,- and transport, the performance assessment should show that the estimated concentration of each hazardous constituent in groundwater in the uppermost aquifer at the point of compliance is less than or equal to the concentration limit for that constituent identified in Section

5. 3.1. 2 above. DOE should provide details of its performance assessment as l

l discussed in Section 2.2 of Reference 20.

5. 3. 3 Closure Performance Demonstration DOE should demonstrate compliance with the closure performance standard in 40 CFR Part 192.02(a)(4) by showing that the need for further maintenance of the i disposal site has been minimized and that the disposal unit controls, minimizes, or eliminates releases of hazardous constituents to the groundwater to the extent necessary to comply with the groundwater protection standard for disposal.

5.3.4 Groundwater Monitoring and Corrective Action Plan DOE should describe an integrated groundwater monitoring and corrective action program for the disposal site as described in Section 2.4 of Reference 20. DOE

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t 26 should discuss or reference procedures for collecting, handling, and analyzing groundwater samples in the monitoring program, as well as general characteristics of the groundwater monitoring program. The program should include collection and analysis of surface water samples to the extent that surface water has been or may be affected by hazardous constituent transport.at the disposal site. The description should demonstrate that the monitoring. i program _ is sufficient to confirm compliance of the disposal unit with the l groundwater protection and closure performance standards. The program should i also describe statistical procedures and criteria for determining aberrant j performances that would trigger analysis and implementation of corrective j actions. DOE should evaluate alternative correction actions that could be -)

implemented if the disposal monitoring program indicates that a disposal unit '

is not performing acceptably. The evaluation should demonstrate that 1 corrective actions could be implemented within 18 months to correct reasonable  !

failure scenarios of the disposal unit. I 1

l 5.4 Groundwater Cleanup l In this section, DOE should demonstrate that proposed groundwater cleanup l l actions at the processing site comply with EPA's groundwater protection j l standards in 40 CFR Part 192, Subparts B and C. Such demonstrations consist of I

the following components: 1) the groundwater cleanup standard, 2) a cleanup demonstration, and 3) a cleanup monitoring program. A more detailed discussion I of that demonstration can be found in Section 3 of Reference 20. j i \

l Aquifer cleanup can be postponed if 00E demonstrates that the disposal l activities will not preclude or preempt cleanup activities and that the i disposal action may proceed independently of cleanup.' Such deferral demonstration should consider, among other things, the interrelationship between the disposal and cleanup actions, the hazards posed by existing ,

contamination, the availability of interim institutional controls to restrict l access to contaminated water, and the rates and directions of contaminant I transport.  !

5. 4.1 Groundwater Cleanup Standard DOE should provide a detailed description of its proposed groundwater cleanup standard for the processing site. The groundwater cleanup standard consists of a list of hazardous constituents and a corresponding list of concentration limits for the constituents. Description of the standard should also identify specific wells that will be used to evaluate compliance with the standard.

5.4.1.1 Hazardous Constituents .

l DOE should identify a list of hazardous constituents that are reasonably expected to be in or derived from residual radioactive- material at the processing site. 00E should justify the list based on characterization of the composition of residual radioactive material, groundwater ' quality data, and l

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contaminated soils. Hazardous constituents should also be identified based on

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analysis'of the processes and reagents used in processing uranium ore.

5.4.1.2, Concentration Limits 00E should propose a concentration limit for each hazardous constituent

' identified above. -The concentration limit will be eitheri the' background concentration of the constituent,c the maximum. constituent level identified 'in --

Table 1 of '40 CFR Part 264.94 as modified by 40 CFR 192.02(a)(3)(ii), or. an alternate concentration limit (ACL). In addition'to providing a proposed. limit for each constituent, DOE _ should justify background limits or ACL's as 3

discussed in Sections 2.1.2 and 3.1.2 of Reference 20.  ;

l 5.4.2 Cleanup-Demonstration 1 00E should provide a detailed description of its . proposed program. to clean up ; '

groundwater at the processing site to comply with' thei concentration limits identified in'Section 5.4.1.2 above. The description ~should include details of-the proposed . steps, procedures,. and schedule .- of the cleanup . program.

~The description should also describe,the extent of groundwater . contamination, -

asses: the rate and direction of hazardous constituent 1 transport, and assess' potential leaching of contaminated soils.

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00E should provide a demonstration that its proposed cleanup program will attain compliance with the cleanup standard discussed in. Section 5.'4.1"above.

The demonstration should include an assessment of tho; effectiveness and efficiency of the cleanup activities. The demonstration should consider. future

' plume movement, including evaluation of such processes as dilution, ' sorption, complexation, and precipitation. A more detailed ' discussion of cleanup demonstrations is provided in Section 3.2 of Reference 20, 5.4.3 Cleanup Monitoring Program 00E should describe its cleanup monitoring program and demonstrate 'that 'the program is adequate to: define'the extent of groundwater contamination; assess t the effectiveness of groundwater cleanup and ' control activities; and. monitor compliance with the groundwater cleanup standard. The description Lshould include or reference procedures for collecting, handling, .and analyzing groundwater samples, as well 'as the general characteristics 'of the monitoring program such as the number, locations, and types of monitoring installations; monitoring frequencies; procedures for evaluating monitoring results; andi action levels that may - trigger' implementation of enhanced monitcring f or revisions to cleanup activities. -

5.5 Supplemental Standards

.Subpart C of the proposed EPA groundwater protection standards fin; 40 CFR p Part 192 [S2 FR 36000] provides for the establishment of supplemental standards l in 111eu of the ~ primary standards in Subparts A and B, as described - in

= _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ __

i 28 Reference 20. At sites where DOE proposes application of supplemental standards for disposal or cleanup, DOE should provide the hydrogeologic characterization information and the conceptual design information described in Sections 5.1 and 5.2 of this document, and the supplemental standards information described below. The characterization and design information requirements are expected to vary based on the type of supplemental standards application.

Supplemental standards applications should consist of the following elements:

(1) applicability demonstration, (2) supplemental standards, (3) demonstration that the remedial action complies with supplemental standards, and (4) demonstration that the remedial action comes as close to meeting the otherwise applicable standard under the circumstances. In addition, DOE should demonstrate that the remedial action is protective of human health and the environment for those cases where supplemental standards are applied because the groundwater is Class III or cleanup is technically impracticable.

DOE should demonstrate that site specific conditions satisfy one of the applicability criteria provided in proposed 40 CFR Part 192.21, including the  ;

Injury Criterion (192.21(a)), Excessive Harm Criterion (192.21(b)),

Impracticability Criterion (192.21(f)), and Class III Criterion (192.21(g)). s The scope and content of each applicability demonstration will vary based on 1 the type of site conditions that make the site eligible for supplemental g standards. For example, in a Class III applicability demonstration, DOE should 9; demonstrate that affected aquifers contain Class III groundwater as defined in  ?

proposed 40 CFR Part 192.11(e) and described in Reference 21. .

The second element of the supplemental standards application is the supplemental standards themselves. DOE should propose specific supplemental standards that can be implemented and enforced through performance analysis or site monitoring. For example, standards can be written as numerical concentration limits for hazardous constituents in groundwater at some location for a specific period of time or as a narrative performance objective that has been tailored for a particular site. Regardless of their form, DOE should clearly identify the proposed supplemental standards.

As the third element of the supplemental standards application, DOE should demonstrate that the remedial action satisfies the proposed supplemental standards. Such compliance demonstrations will vary based on the form of the supplemental standards. For example, if DOE proposes numerical concentration limits for hazardous constituents in groundwater at some location downgradient from a disposal cell, the demonstration would consist of analysis of the design and performance of the disposal cell and a comparison of projected concentrations of the constituents with the limits at the compliance location.

In other cases where DOE does not propose numerical limits, compliance demonstrations could consist of an assessment of the potential for human and environmental exposure and a determination that the probability of exposure is low enough to prevent adverse impacts from groundwater contamination.

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29 The fourth element 'of supplemental standards.' applications consists of a j demonstration-that the remedial action comes as close to meeting the otherwise s applicable - standards as is reasonable under the circumstances. DOE should clearly describe the conditions that' influence the risks posed by groundwater contamination, identify the otherwise applicable standards, assess alternative remedial action approaches to comply with the otherwise applicable standards, and demonstrate that the proposed remedial action comes as close to meeting these standards as is reasonable. DOE's identification of the otherwise applicable standards should be complete enough to evaluate the relative costs and benefits' of alternative remedial measures. For example, the otherwise applicable standards for a disposal. site would consist 'of specific concentration limits for hazardous constituents in groundwater at the point of compliance.

At- those sites where supplemental standards for cleanup apply because the groundwater is Class III or cleanup is technically ' impracticable, DOE should demonstrate that the remedial action for restoration is sufficient to assure protection of human health and the environment. . Such demonstrations should consider the types of information and assessments used. to support alternate concentration limits, as described in Reference 22. The demonstrations should also consider the need for measures, such as institutional controls to restrict l access to contaminated groundwater, that may not otherwise be acceptable to l demonstrate compliance with the primary standards in Subparts A and B. j i

5.6 Summary )

i DOE should provide a summary description of its demonstration of compliance i with the EPA groundwater protection standards contained in 40 CFR Part 192, [

Subparts A-C. DOE should also summarize any. unresolved items that need to be l resolved prior to obtaining NRC concurrence, including the strategy and I schedule'for their resolution. 1 1

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30 6 RADON ATTENUATION AND SITE CLEANUP The proposed remedial action must meet the EPA standards that deal with limiting the release of Radon-222 and with clean-up of contaminated land and buildings. For DOE to demonstrate this, the remedial action documentation must contain 1) appropriate analyses that demonstrate that the design thickness of the radon barrier will meet the EPA standard for radon release and 2) details of the plans and procedures for radiological survey and clean-up.

6.1 Radon Attenuation A thorough description of the radon barrier design (calculational methodology and results) must be provided along with the geotechnical and radiological information supporting the selection of those properties of the tailings and radon barrier materials that are necessary to the radon barrier design.

6.1.1 Selection of Parameters Information must be provided to demonstrate that the estimates of the material parameters that are used in the calculational methodology lead to a reasonably conservative estimate of the radon flux at the top of the radon barrier.

Specific parameters that must be considered in the design of the radon barrier include: long-term moisture content, radon diffusion coefficient, radium content, radon emanation coefficient, material thickness, bul k density, specific gravity, and porosity.

Whenever site-specific measured parameter values are utilized, they should be accompanied by supporting information describing the test method, its precision and accuracy, and its applicability for representing the long-term attenuating capability of the radon barrier materials. This supporting information need not be repeated in the RAP documentation if the procedures used are already referenced in the HRC Standard Review Plan and have been used in other projects to date. Summary tables and plots should be provided which catalog the important test results. Based on the results of the testing and exploration programs, a table indicating the values of the parameters actually used in the design should be presented. Discussion pertinent to this table should include an explanation of how the test data were enveloped for design and why the design envelope is conservative.

6.1.2 Calculational Methodology and Design Results The generally accepted and utilized methodology for the radon barrier design uses computer codes (RAECO, RAECOM, RADON) which apply one-dimensional, steady-state gas diffusion theory (Ref. 23). The remedial action documentation should include diagrams of the modeled sections through the disposal cell and any other information that would enable the radon barrier computations to be verified by the NRC staff. A radon barrier thickness design summary should be presented.

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31 Since the radon barrier is also an infiltration barrie~r, ' it serves dual.

functions. The' significance of its thickness and possibly built-in conservatism in the context of satisfying its dual functions should be  :

discussed.

If this discussion is provided elsewhere in the-RAP-documentation, i then a cross reference would be appropriate.

Other calculational methods which estimate the average ' surface radon release

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from the covered disposal cell or which estimate the

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annual average 1 concentration of radon in air at or above any location outside the disposal site may be used. In these cases,. similar information regarding input parameters and design results should be presented. However, it must'also be  !

shown' that the selected alternative method produces reliable estimates by I providing references for the methodology and description of the numerical or analytical models used.

6.2 Processing Site Cleanup '

This section should include descriptions of 1) the extent of' contamination at the processing site, not included in the disposal site, 2) the standards to be met in the processing site cleanup, and 3) the method (s) to be used to verify that clean-up has been accomplished. ]

l l 6.2.1 Radiological Site Characterization In this section, DOE should decribe the background radiological concentrations, and the radiological characteristics of the processing site.

/l This should include the areal extent and depth of contamination in the soil. .The level-of  !

l contamination in buildings to be released for ~ unrestricted .use should also be I described. i 6.2.2 Standards Used for Cleanup This section should include a commitment to clean up all materials that are in excess of the EPA standards (Subpart B), or a justification for the use of l supplemental standards (Subpart C). In addition, a commitment should be presented to clean up surface contamination on equipment and structures to be released for unrestricted use to a level that would allow such release.

6.2.3 Verification of Cleanup In this section, DOE should specify which procedures -will be used to verify that the cleanup has been accomplished in accordance with the commitments in Section 6.2.2. If any of this information is generically presented elsewhere, such information need not be repeated here but should be appropriately j referenced.

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'32 6.3 Summary DOE- 'should summarize 'the 'results' of. their evaluation regarding . radon attenuation and site clean-up; during' remedial ' action and their conclusions-regarding the ability of the remedial action to meet the EPA standard.

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I 33 APPENDIX'A

) 1 REFERENCES / BIBLIOGRAPHY l l

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-1. U.S. Environmental Protection Agency,-40 CFR Part 192, " Standards for )

Remedial Actions at Inactive Uranium Processing Sites; Proposed ]

Rule," 52 FR 36000, September 24, 1987. l

2. Hunt, ' C. B. , 1974, - Natural regions of the United States and Canada: ,

San Francisco, W.H. Freeman and Company, 725 p.  !

3. USGS.(and U.S. Bureau of Mines), 1980, Principles of a- .

resource / reserve classification for minerals: U.S. Geological Survey, Circular 831, 5'p.

l

4. Folk, R.L., 1980, Petrology of sedimentary rocks: Austin, TX, Hemphill Publishing Company, 185 p.

5. Lutton, R.J., Butler, D. K. , Meade, R.B., Patrick, D.M., Strong, A.B., and Taylor, H.M., 1982, Tests for evaluating sites for disposal of low-level' radioactive waste: ' U. S. Nuclear Regulatory Commission, NUREG/CR-3038_. 36 p., appendices.

6. Schumm, S.A. and Chorley, R.J.. 1983, Geomorphic controls on the management of nuclear waste: U.S. Nuclear Regulatory-Commission, NUREG/CR-3276, 137 p.

7. Patton, P.C. and Schumm, S.A., 1975, Gully erosion, northern Colorado: a threshold phenomenon: Geology, v. 3, p. 88-90.

8. Nelson, J.D., Volpe, R.L, Wardwell, R.E., Schumm, S.A., and Staub, W.P., 1983, ' Design -considerations for long-term '

stabilization of uranium mill tailings impoundments: '

U.S. Nuclear Regulatory Commission, NUREG/CR-3397, 163 p.

9 Nelson, J.D. , Abt, S. R. , Volpe, R. L. , van Zyl, D. , Hinkle, N. E. , and Staub, W. P. , 1986, Methodologies for evaluating 'long-term.

stabilization designs of uranium mill tailings impoundments:

U.S. Nuclear Regulatory Commission, NUREG/CR-4620, 145_p. -

10. Bernreuter, D. L. , Savy, J.B. ,. Mensing, R.W. , and Chung, D.H. ,_1984, Seismic hazard characterization of the eastern United States:

methodology and interim results for ten sites: U.S. Nuclear Regulatory Commission, NUREG/CR-3756, 217 p., appendices.

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11. Seed, H.B. and Idriss, I.M., 1982, Ground motion and soil j liquefaction during earthquakes: Berkely, CA, Earthquake i Engineering Research Institute, 134 p. {

1

12. Campbell, K.W., 1981, Near source attenuation of peak horizontal acceleration: Bulletin of the Seismological Society of America, l i

v. 71, p. 2039-2070. I

13. _, 1982, A preliminary methodology for the regional zonation of peak ground acceleration: Proceedings of the 3rd International Earthquake Microzonation Conference, Seattle, Washington, v. 1, p. 365-376.

14. Joyner, W.B. and Boore, D.M., 1981, Peak horizontal acceleration and velocity from strong motion records including records from the 1979 Imperial Valley, Califo.:?9 earthquake: Bulletin of the Seismological Society of America, v. 71, p. 2011-2038.

15. U.S. Nuclear Regulatory Commission, " Standard Review Plan for UMTRCA Title I Mill Tailings Remedial Action Plans", October 1985.

16. U.S. Nuclear Regulatory Commission, Regulatory Guide 1.132, " Site Investigations for Foundations of Nuclear Power Plants," Rev.1, March 1979. '

17. U.S. Nuclear Regulatory Commission, Regulatory Guide 1.138,

" Laboratory Investigations of Soils for Engineering Analysis and <

Design of Nuclear Power Plants," April 1978.

18. U. S. Nuclear Regulatory Commission, " Staff Technical Position on Test'ing and Inspection Plans During Construction of DOE's Remedial Action at Inactive Uranium Mill Tailings Sites".

l 19. U. S. Geological Survey, Water Supply Paper 1887, " Maximum Floodflow in the Conterminous United States", 1977.

20. U.S. Nuclear Regulatory Commission, Technical Position, "Information Needs to Demonstrate Compliance with EPA's Proposed Ground Water Protection Standards in 40 CFR Part 192, Subparts A-C, June, 1988.

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21. U.S. Environmental Protection Agency, " Guidelines for Ground-Water.

Classification under the EPA Ground-Water Protection Strategy,"

December 1986.

22. U.S. Nuclear Regulatory Commission, " Draft Technical Position on s Alternate Concentration Limits for - Uranium Mills," June 1988.-

23. Rogers, U.C., Nielson, K.K. , and Kalkwarf, D.R. , " Radon Attenuation Handbook.for Uranium Mill Tailings Cover Design", NUREG/CR-3533, April 1984.

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