4. ROD - Former Screening Plant and Surrounding Properties OU 2 - May 2010.pdf

RECORD OF DECISION

FOR

LIBBY ASBESTOS SUPERFUND SITE

THE FORMER SCREENING PLANT AND

SURROUNDING PROPERTIES

OPERABLE UNIT 2

LINCOLN COUNTY, MONTANA

May 2010

LIBBY ASBESTOS SUPERFUND SITE

THE FORMER SCREENING PLANT AND SURROUNDING

PROPERTIES

Part 1 Declaration

D-1

Site Name and Location The Libby Asbestos Superfund Site (Libby site) (CERCLIS #MT0009083840) is located in and around the Town of Libby, Montana. Libby is the county seat of Lincoln County and is in the northwest corner of Montana, about 35 miles east of Idaho and 65 miles south of Canada (Exhibit 1-1). Operable Unit 2 (OU2), also known as the “former screening plant and surrounding properties,” is one of eight OUs at the site and is located near the intersection of Highway 37 and Rainy Creek Road, approximately 5 miles north of town.

Statement of Basis and Purpose This decision document presents the selected remedy for OU2. The remedy selected in this ROD was chosen in accordance with the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and Reauthorization Act of 1986 and the National Oil and Hazardous Substance Pollution Contingency Plan (NCP). The decision is based on the administrative record file for OU2 of the site. This document is issued by the EPA Region 8, the lead agency, and the Montana Department of Environmental Quality (MDEQ). Both EPA and MDEQ concur on the selected remedy presented herein.

The remedial action selected in this ROD is necessary to protect public health and welfare and the environment from actual or threatened releases of hazardous substances at the site. It will reduce the public health risks by blocking contaminant pathways to the available receptors. However, the selected remedy must be reevaluated when the site-wide risk assessment is completed. An ecological risk assessment is being developed at the mine site, OU3. Once that work is complete, EPA will build upon information gathered during the risk assessment for OU3 to identify potential pathways and receptors to evaluate ecological risk at OU2.

Assessment of Site The response action selected in this ROD is necessary to protect the public health and welfare and the environment from actual or threatened releases of hazardous substances into the environment.

Description of Selected Remedy The majority of the OU has already been remediated through past removal actions.

The selected remedy will eliminate the remaining exposure pathway to the Libby Asbestos (LA) contamination present at the OU by removing the waste (in surface soils near sample location 1-03000) and by breaking the exposure pathway associated with disturbance of the source materials by in-place containment (contaminated soil within the west embankment of Highway 37). Institutional controls (ICs) and statutory reviews (five-year and other) will provide assurance that the integrity of the remedy will be protected.

EPA will also conduct a review to evaluate effectiveness of the remedy, as soon as sufficient new information concerning toxicity factors is available. If unacceptable

D-2 exposures are identified, EPA will take action as necessary to ensure that the soil-to-air pathway is broken. Actions may include additional excavation, improving covers, and/or strengthening ICs When the site-wide risk assessment is completed, the ICs will be revisited to determine whether any modification is needed.

Statutory Determinations The selected remedy meets the mandates of CERCLA §121 and the National Contingency Plan. The remedy is protective of human health and the environment. It complies with all federal and state requirements that are applicable or relevant and appropriate to the remedial action, is cost effective, and utilizes permanent solutions and alternative treatment technologies to the maximum extent practicable.

The remedy does not satisfy the statutory preference for treatment as a principal element of the remedy (this preference is triggered by the presence of a principal threat waste). Treatment of LA is not viable at OU2 for several reasons:

High relative cost. Thermo-chemical treatment of asbestos wastes is significantly more expensive than off-site disposal. Because the wastes must be shipped to an off-site treatment facility in another state, treated, and then shipped back to the site for disposal, transportation costs are also disproportionately high given the small volume of wastes that would be removed

Inaccessibility of waste material. Unless the design process finds that the structural integrity of the roadway would not be compromised by removing the soils, the highway right-of-way soils will be addressed through containment rather than removal. Treatment would not be possible because wastes would not be removed and thus could not be treated.

Lack of irreversibility data. In addition to the cost issues related to treatment, the treatment technology is relatively new, so extensive data are not available to confirm long-term irreversibility of the treatment process.

Ongoing need for monitoring and five-year reviews. Subsurface waste material will remain at depth at the site, so the treatment of the small amounts of remaining near surface LA would not negate the need for ongoing monitoring and five-year reviews. Thus no efficiencies or savings are gained regarding treatment in terms of long-term protectiveness

As noted above, a statutory review will be conducted within five years after initiation of remedial action to ensure that the remedy is, or will be, protective of human health and the environment.

Future Public Comment When the site-wide risk assessment is complete, the agencies will re-evaluate the remedy in accordance with the review requirements at CERCLA Section 121(c). This determination will be published and an opportunity for public comment will be

D-3 provided. Similar opportunities for public comment will be provided at the time of the subsequent five-year reviews.

ROD Data Certification Checklist Once a quantitative site-wide risk assessment is completed and a cleanup level is established, the ROD for this OU will be modified, as appropriate. If modified, the ROD will include this new information and will incorporate all necessary remedial actions, modifications of the ICs, and modifications to operation and maintenance plans in order to properly manage the residual contamination in a manner that will protect human health and the environment.

The following information is included in the decision summary section (Part 2) of this ROD. Additional information can by found in the administrative record file for this site.

Contaminants of concern and their respective concentrations

Risks represented by the contaminants of concern

How source materials constituting principal threats are addressed

Current and reasonably anticipated future land use assumptions used in the risk assessment

Potential land use that will be available at the Site as a result of the selected remedy

Estimated capital, annual operation and maintenance (O&M), and total present worth costs, discount rate, and the number of years over which the remedy cost estimates are projected

Key factors that led to selecting the remedy

Cleanup criteria for levels of concern and the basis for those levels are typically included in a ROD. However, a site-wide risk assessment has not yet been completed.

Although an OU-specific human health risk assessment was conducted for OU2, it did not include LA-specific toxicity values. In the absence of established quantitative, risk-based cleanup levels, EPA is removing and/or capping all visible vermiculite and any detectable LA thereby breaking complete exposure pathways and reducing future potential risk for LA exposure. Exceptions include those circumstances where vermiculite is otherwise well-contained. If LA source materials are encountered during excavation activities, removal will continue until the source material is removed (to a maximum of 3 feet). If contamination continues below 3 feet, a visible barrier marking the extent of excavation will be placed before backfilling. Once sufficient data are obtained to establish the LA-specific toxicity values, the site-wide risk assessment will be conducted.

LIBBY ASBESTOS SUPERFUND SITE

THE FORMER SCREENING PLANT AND SURROUNDING

PROPERTIES

Part 2

Decision Summary i

Table of Contents

Part 1 Declaration

Part 2 Decision Summary

Section 1 Introduction

1.1 Site Name and Location ............................................................................. 1-1

1.2 Key Features of the Libby Site and OU2 .................................................. 1-1

1.2.1 Site OUs ......................................................................................... 1-1

1.2.2 Site Contamination ...................................................................... 1-3

1.3 ROD Format ................................................................................................. 1-4

Section 2 Site History and Response Activities

2.1 Site Background and History .................................................................... 2-1

2.1.1 Former Screening Plant (Subarea 1) .......................................... 2-2

2.1.2 Flyway (Subarea 2) ...................................................................... 2-3

2.1.3 Private Property (Subarea 3) ...................................................... 2-4

2.1.4 Rainy Creek Road Frontage (Subarea 4) ................................... 2-4

2.2 Response Activities ..................................................................................... 2-5

2.2.1 Site-Wide EPA Activities ............................................................ 2-5

2.2.1.1 Activities Conducted Prior to NPL Listing .............. 2-5

2.2.1.2 Activities Conducted After NPL Listing .................. 2-6

2.2.2 OU-Specific Response Activities ................................................ 2-7

2.2.2.1 Former Screening Plant (Subarea 1) .......................... 2-7

2.2.2.2 Flyway Investigation and Removal Activities

(Subarea 2) .................................................................. 2-11

2.2.2.3 Private Property (Subarea 3) .................................... 2-12

2.2.2.4 Rainy Creek Road Frontages (Subarea 4) ............... 2-13

2.3 Summary of Data Sources and Quality Assurance/Quality Control 2-13

2.4 Summary of Sampling and Analysis Methods ..................................... 2-14

Section 3 Highlights of Community Participation

3.1 Conducted Interviews and Prepared the CIP ......................................... 3-1

3.2 Established a Local Information Center & an Information

Repository .................................................................................................... 3-2

3.3 Established an On-site CI Team ................................................................ 3-2

3.4 Provided Support to the Real Estate Community .................................. 3-2

3.5 Provided Education to Stakeholders via Classes and Workshops ....... 3-3

3.6 Provided Support to TAG and CAG ........................................................ 3-3 ii

3.7 Developed a Site Mailing List and Prepared and Distributed Multiple Fact Sheets ................................................................................... 3-3

3.8 Published Advertisements ......................................................................... 3-3

3.9 Developed and Distributed Informational Brochures, Written

Materials, and a Website ............................................................................ 3-4

3.10 Held Public Meetings and Availability Sessions and Updated

Commissioners ............................................................................................ 3-4

3.11 Implemented Targeted Informational Campaigns ................................. 3-4

3.12 Issued Proposed Plans, Held a Public Hearing, and Developed

Responsiveness Summaries and RODs ................................................... 3-4

Section 4 Scope and Role of Operable Unit

Section 5 Summary of Site Characteristics

5.1 Site Overview ............................................................................................... 5-1

5.1.1 Surface Features and Size ........................................................... 5-1

5.1.2 Climate .......................................................................................... 5-1

5.1.3 Areas of Archeological or Historical Importance .................... 5-2

5.1.4 Geology ......................................................................................... 5-2

5.1.5 Soil .................................................................................................. 5-2

5.1.6 Surface Water Hydrology ........................................................... 5-3

5.1.7 Hydrogeology............................................................................... 5-4

5.2 Conceptual Site Model ............................................................................... 5-4

5.2.1 Affected Media ............................................................................. 5-6

5.2.2 Migration Routes and Exposure Pathways .............................. 5-6

5.2.3 Population That Are or Could Be Affected .............................. 5-7

Section 6 Current and Potential Future Land Resource Uses

6.1 Land Use ....................................................................................................... 6-1

6.2 Groundwater Use ........................................................................................ 6-1

6.3 Surface Water Use ....................................................................................... 6-1

Section 7 Summary of Site Risks

7.1 Exposure Assessment ................................................................................. 7-2

7.1.1 Conceptual Site Models .............................................................. 7-2

7.1.1.1 Pre-Cleanup Conditions ............................................. 7-2

7.1.1.2 Post-Cleanup Conditions ............................................ 7-3

7.1.2 Quantification of Exposure ......................................................... 7-4

7.2 Toxicity Assessment ................................................................................... 7-5

7.2.1 Non-Cancer Effects ...................................................................... 7-6

7.2.1.1 Asbestosis ..................................................................... 7-6

7.2.1.2 Pleural Abnormalities ................................................. 7-6

7.2.1.3 Observations of Asbestos-Related Non-Cancer

Disease in People Exposed to LA .............................. 7-6 iii

7.2.2 Cancer Effects ............................................................................... 7-7

7.2.2.1 Lung Cancer ................................................................. 7-7

7.2.2.2 Mesothelioma ............................................................... 7-7

7.2.2.3 Other Cancers ............................................................... 7-7

7.2.2.4 Observations of Asbestos-Related Cancers Cases in

Workers in Libby ......................................................... 7-7

7.2.3 Toxicity Values ............................................................................. 7-8

7.3 Characterization of Risk ............................................................................. 7-8

7.3.1 Risk from Ambient Air ................................................................ 7-8

7.3.2 Risk from Soil Disturbances in Area of Remediated Soil ....... 7-8

7.3.3 Risks from Soil Disturbances in Areas of Current or

Potential Future Surface Contamination .................................. 7-8

7.4 Summary of Human Health Risk ............................................................. 7-8

7.5 Ecological Risk ............................................................................................. 7-9

7.6 Basis of Action ............................................................................................. 7-9

Section 8 Remedial Action Objectives and Remedial Goals

8.1 Remedial Action Objectives ....................................................................... 8-1

8.2 Remediation Goals ...................................................................................... 8-2

Section 9 Description of Alternatives

9.1 Description of Remedy Components ....................................................... 9-2

9.1.1 Alternative 1: No Action ............................................................. 9-2

9.1.2 Alternative 2: ICs and Engineered Controls with

Monitoring .................................................................................... 9-2

9.1.3 Alternative 3a: In-Place Containment of Contaminated Soil within the Flyway Subarea, ICs and Engineered Controls with Monitoring ........................................................................... 9-3

9.1.4 Alternative 3b: In-Place Contaminant and Removal of

Contaminated Soil within the Flyway Subarea, Offsite Disposal at the Former Libby Vermiculite Mine, ICs and Engineered Controls with Monitoring ...................................... 9-4

9.1.5 Alternative 4: Removal of Contaminated Soil within the

Flyway Subarea, Offsite Disposal at the Former Libby Vermiculite Mine, ICs and Engineered Controls with Monitoring .................................................................................... 9-5

9.1.6 Alternative 5: Removal of Contaminated Soil within the

Flyway Subarea, Offsite Thermo-Chemical Treatment and Reuse of Treated Material, ICs and Engineered Controls with Monitoring ........................................................................... 9-6

9.2 Common Elements and Distinguishing Features of Each

Alternative .................................................................................................... 9-7

9.2.1 Contaminant Removal ................................................................ 9-7

9.2.2 Covers ............................................................................................ 9-7 iv

9.2.3 Off-Site Disposal .......................................................................... 9-7

9.2.4 Off-Site Treatment Technology .................................................. 9-7

9.2.5 ICs and Engineering Controls with Monitoring ...................... 9-8

9.2.6 Five-Years Reviews ...................................................................... 9-8

Section 10 Comparative Analysis of Alternatives

10.1 Threshold Criteria ..................................................................................... 10-1

10.1.1 Overall Protection of Human Health and the

Environment ............................................................................... 10-1

10.1.2 Compliance with ARARs .......................................................... 10-2

10.2 Balancing Criteria ...................................................................................... 10-5

10.2.1 Long-Term Effectiveness and Permanence ............................ 10-5

10.2.2 Reduction of Toxicity, Mobility, or Volume through

Treatment .................................................................................... 10-5

10.2.3 Short-Term Effectiveness .......................................................... 10-5

10.2.4 Implementability ........................................................................ 10-6

10.2.5 Cost .............................................................................................. 10-7

10.3 Modifying Criteria .................................................................................... 10-7

10.3.1 State Acceptance ........................................................................ 10-8

10.3.2 Public Acceptance ...................................................................... 10-8

10.3.3 Modifications Made as a Result of Comment ........................ 10-8

Section 11 Principal Threat Wastes

Section 12 Selected Remedy

12.1 Short Description of the Selected Remedy ............................................ 12-1

12.2 Rationale for the Selected Remedy ......................................................... 12-2

12.3 Detailed Description of the Selected Remedy ....................................... 12-3

12.4 Removal and Containment ...................................................................... 12-3

12.4.1 ICs ................................................................................................ 12-4

12.4.2 Operations and Maintenance ................................................... 12-5

12.5 Estimated Cost of the Selected Remedy ................................................. 12-5

12.6 Expected Outcomes of the Selected Remedy ........................................ 12-5

12.7 Performance Standards ............................................................................ 12-6

Section 13 Statutory Determinations

13.1 Protection of Human Health and the Environment ............................. 13-1

13.2 Compliance with ARARs ......................................................................... 13-1

13.2.1 Contaminant Sources ................................................................ 13-2

13.2.2 Surface Water ............................................................................. 13-2

13.2.3 Other ARARs .............................................................................. 13-3

13.3 Cost Effectiveness ...................................................................................... 13-3 v

13.4 Utilization of Permanent Solutions and Alternative Treatment (or Resource Recovery) Technologies to the Maximum Extent Practicable .................................................................................................. 13-4

13.5 Preference for Treatment as a Principal Element ................................. 13-4

13.6 Five-Year Reviews ..................................................................................... 13-4

Section 14 Documentation of Significant Changes

Section 15 References

Part 3 Responsiveness Summary

List of Exhibits Exhibit 1-1 ............................................................................................................ Site Location Map Exhibit 1-2 ...................................................................................................... OUs at The Libby Site Exhibit 1-3 .............................................................. The Superfund Process – The Road to the ROD Exhibit 2-1 .............................................................. History of Mining Activities Relevant to OU2 Exhibit 2-2 ............................................................................................................. OU2 Site Layout Exhibit 2-3 ....................................... Response and Mining/Industrial Activities Relevant to OU2 Exhibit 2-4 ................................................................. Summary of Investigation Activities at OU2 Exhibit 2-5 ........................................................... Summary of Response Action Removals at OU2 Exhibit 5-1 .......... Summary of Current Status of Exposure Pathways after Past Response Actions Exhibit 5-2 ......... Summary of Current Status of Risks at OU2 after the Interim Remedial Actions Exhibit 7-1 ............................................................. CSM for Current and Future Land Use at OU2 Exhibit 9-1 ............................................ Remedy Components Used in OU2 Remedial Alternatives Exhibit 10-1 ........................................ Summary of Comparative Analysis of Alternatives for OU2 Exhibit 12-1 ......................................................................... Areas to be Addressed in OU2 Remedy Exhibit 12-2 .............................................................. Cost Estimate Summary for Selected Remedy Exhibit 13-1 ....................................... Evaluation of Compliance with ARARs for Selected Remedy

Appendix A Summary of Compliance with Federal and State Applicable or Relevant and

Appropriate Requirements vi

Acronyms ABS .......................................................................................................... activity based sampling ACM ................................................................................................ asbestos containing material ARAR ..................................................... applicable or relevant and appropriate requirement BMPs .................................................................................................. best management practices BNSF ............................................................................................. Burlington Northern Santa Fe CAG ............................................................................................... Community Advisory Group CDM ................................................................................. CDM Federal Programs Corporation CERCLA ....... Comprehensive Environmental Response, Compensation, and Liability Act CICs ................................................................................ community involvement coordinators CSM ............................................................................................................ conceptual site model CSS ................................................................................................ Contaminant Screening Study DQOs ......................................................................................................... data quality objectives EPA ............................................................... United States Environmental Protection Agency ERS ....................................................................................... Environmental Resource Specialist FS ........................................................................................................................... feasibility study ft2 ................................................................................................................................... square foot Grace ................................................................................................... W.R. Grace and Company ICs ................................................................................................................. institutional controls KDC ................................................................................... Kootenai Development Corporation Libby site .................................................................................... Libby Asbestos Superfund Site LA ........................................................................................................ Libby amphibole asbestos MCL ................................................................................................ maximum contaminant level MDEQ ........................................................... Montana Department of Environmental Quality MDT .............................................................................Montana Department of Transportation NCP ...................... National Oil and Hazardous Substances Pollution & Contingency Plan ND ................................................................................................................................... non-detect NPL ............................................................................................................National Priorities List O&M ................................................................................................. operation and maintenance OU .............................................................................................................................. operable unit PLM ................................................................................................... polarized light microscopy PLM-VE ....................................... polarized light microscopy visual area estimation method PPE ...............................................................................................personal protective equipment QA/QC ................................................................................. quality assurance/quality control RAO ....................................................................................................... remedial action objective RG ............................................................................................................................. remedial goal RI ................................................................................................................ remedial investigation ROD ................................................................................................................... record of decision s/cc ............................................................................................. structures per cubic centimeter TAG .................................................................................................. Technical Assistance Group TCCT ............................................................................ thermo-chemical conversion treatment TEM ...................................................................................... transmission electron microscopy °F ...................................................................................................................... degrees Fahrenheit vii

< .......................................................................................................................................... less than ≥ ................................................................................................................ equal to or greater than % ........................................................................................................................................... percent viii

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Exhibit 1-1. Site Location Map

Section 1 Introduction

1.1 Site Name and

Location The Libby Asbestos Superfund Site (Libby site) (CERCLIS # MT0009083840) is located in and around the Town of Libby, Montana. Libby is the county seat of Lincoln County and is in the northwest corner of Montana, about 35 miles east of Idaho and 65 miles south of Canada (Exhibit 1-1). The town lies in a picturesque valley carved by the Kootenai River and framed by the Cabinet Mountains to the south. The community's assets include clean water, beautiful scenery, and recreational opportunities such as fishing, hiking, hunting, boating and skiing.

Operable Unit 2 (OU2), also known as the former Screening Plant and Surrounding Properties. It is located near the intersection of Highway 37 and Rainy Creek Road, approximately 5 miles north of town.

1.2 Key Features of the Libby Site and OU2

1.2.1 Site OUs

To facilitate a multi-phase approach to remediation of the Libby site, eight separate OUs have been established. These OUs are shown on Exhibit 1-2 and include:

OU1. The former Export Plant is situated on the south side of the Kootenai River, just north of the downtown area of the City of Libby, Montana. OU1 includes the embankments of Montana Highway 37, the former Export Plant, and Riverside Park. The property is bounded by the Kootenai River on the north, Highway 37 on the east, the Burlington Northern Santa Fe (BNSF) railroad thoroughfare on the south, and State of Montana property on the west.

Section 1 Introduction

1-2

Exhibit 1-2 OUs at The Libby Site

1-3

OU2. OU2 includes areas impacted by contamination released from the former Screening Plant. These areas include the former Screening Plant (Subarea 1), the Flyway property (Subarea 2), a privately-owned property (Subarea 3), and the Rainy Creek Road Frontage and Highway 37 right-of-way adjacent to Rainy Creek Road (Subarea 4).

OU3. The mine OU includes the former vermiculite mine and the geographic area (including ponds) surrounding the former vermiculite mine that has been impacted by releases from the mine, including Rainy Creek and the Kootenai River. Rainy Creek Road is also included in OU3. The geographic area of OU3 is based primarily upon the extent of contamination associated with releases from the former vermiculite mine.

OU4. OU4 is defined as residential, commercial, industrial (not associated with former W.R. Grace Company [Grace] operations), and public properties, including schools and parks in and around the City of Libby, or those that have received material from the mine not associated with Grace operations. OU4 includes only those properties not included in other OUs.

OU5. OU5 includes all properties that were part of the former Stimson Lumber Mill and that are now owned and managed by the Kootenai Business Park Industrial Authority.

OU6. The rail yard owned and operated by BNSF is defined geographically by the BNSF property boundaries and extent of contamination associated with BNSF rail operations. Railroad transportation corridors are also included in this OU and have not been geographically defined.

OU7. The Troy OU includes all residential, commercial, and public properties in and around the Town of Troy, approximately 20 miles west of downtown Libby.

OU8. OU8 is comprised of the US and Montana State highways and secondary highways that lie within the boundaries of OU4 and OU7.

1.2.2 Site Contamination

OU2 was historically owned and used by Grace for stockpiling, staging, and distributing vermiculite and vermiculite concentrate to vermiculite processing areas and insulation distributors outside of Libby. The vermiculite deposit that was mined by Grace contains a distinct form of naturally-occurring amphibole asbestos that is comprised of a range of mineral types and morphologies. In various past reports, this form of amphibole asbestos has been termed interchangeably by the EPA as Libby amphibole asbestos or Libby asbestos (LA). The term LA refers generally to amphibole materials that originated in the Libby vermiculite deposit, have the ability to form durable, long, and thin structures that are generally respirable, can reasonably be expected to cause disease, and hence are considered the contaminant of concern at the site.

1-4

Because vermiculite mined from Libby has been found to be contaminated with LA, known to cause human health effects, the United States Environmental Protection Agency (EPA) initiated an emergency response action in November 1999 to address questions and concerns raised by citizens of Libby regarding possible ongoing exposures to asbestos fibers as a result of historical mining, processing, and exportation of asbestos-containing vermiculite.

Vermiculite and LA are present in subsurface soil. Exposure to the residual contamination has been mitigated by removal of surface soils and the extensive cap placed across the OU during removal activities, with the exception of an isolated portion of the Highway 37 right-of-way and in the area surrounding sample location 1-03000. Both of these locations are within the Flyway (Subarea 2).Contamination at depth is present in each of the subareas at the site as described below:

Former Screening Plant (Subarea 1). The majority of residual contamination is present at depths greater than or equal to 4 feet below ground surface (bgs) and in several isolated areas at depths less than 4 feet bgs within the former Screening Plant area north of Rainy Creek. In general, removal activities in this subarea were pre-established to 4 feet bgs and contamination was encountered at this depth.

The Flyway (Subarea 2). The majority of excavated areas in the Flyway met EPA’s clearance criteria of less than (<) 1 percent (%) LA at depth, at depths varying from less than 1 foot bgs to greater than 4 feet bgs. However, LA concentrations ≥1% have been detected in confirmatory soil samples collected at the eastern boundary of the Flyway within the Highway 37 right-of-way at depths up to 2 feet bgs. Within the Highway 37 right-of-way is an isolated area with concentrations of LA of greater than (>)1% at less than 1 foot bgs. LA was also observed in surface soils in one area (area surrounding sample 1-03000) not previously remediated at concentrations of <1%.

Private Property (Subarea 3). The majority of this subarea does not contain residual contamination; however, one confirmation soil sample collected along the northern portion of the property contained <1% LA at a depth of 1 foot bgs.

Rainy Creek Road Frontages (Subarea 4). Residual contamination is present along these frontages at a depth between 1 and 2 feet bgs.

The details regarding how the above conclusions were reached are provided in the remedial investigation (RI) report (EPA 2009a) and are briefly discussed in Section 2.

1.3 ROD Format

This Record of Decision (ROD) is the decision document at the end of a detailed investigation and evaluation of conditions at OU2 (Exhibit 1-3). Since the selected remedy will leave waste in place, the remedy will be evaluated at least every five years to ensure that the remedy remains protective. Any new information that may

1-5 impact portectiveness of the remedy will be considered in accordance with the review requirements at CERCLA Section 121(c).

If unacceptable exposures are identified, EPA will take action as necessary to ensure that the soil-to-air pathway is broken. Actions may include additional excavation, improving covers, and/or strengthening institutional controls (ICs). It is anticipated that current research efforts will result in data that will contribute to the development of LA-specific toxicity values. When those toxicity values are available, EPA will reevaluate this remedy to ensure continued protectiveness.

Once the remedy has been implemented and performance standards have been met, there will be an opportunity to delete this operable unit from the national priorities list. ICs and operation and maintenance (O&M) will continue. Deletion from the National Priorities List (NPL) does not preclude any additional response actions to ensure protectiveness of the remedy.

EPA’s detailed investigation and evaluation of conditions at OU2 included performance of a remedial investigation/feasibility study (RI/FS) for OU2 and the

Exhibit 1-3. The Superfund Process – The Road to the ROD

1-6 completion of numerous removal actions to address significant human health risks during completion of the RI and FS. The RI report for OU2 includes a comprehensive description of the nature and extent of contamination and a description of past investigative and removal actions at the site, as well as the risk assessment. The FS report for OU2 uses information from the RI to perform a systematic analysis to determine the need for, and scope of, any required remedial action. The steps leading up to the ROD also included numerous opportunities for public involvement, including preparation of a proposed plan (mailed to all Libby residents on September 14, 2009), a public meeting, and a 120-day public comment period.

This ROD documents EPA’s selected remedy for OU2. The next step in the Superfund process will be completion of a remedial design followed by implementation of a remedial action based on the selected remedy documented in this ROD.

This ROD is organized into the following sections:

Section 1 – Introduction. Provides a very brief introduction to the ROD.

Section 2 – Site History and Response Activities. Provides a brief history of the site, OU2, and EPA’s activities.

Section 3 – Highlights of Community Participation. Describes the range of community outreach activities conducted site wide and at OU2.

Section 4 – Scope and Role of OU2. Describes how the actions taken at OU2 fit into the overall scope of the Libby site.

Section 5 – Summary of Site Characteristics. Contains an overview of the site, conceptual site model (CSM), and a summary of the results of the RI.

Section 6 – Current and Potential Future Land and Resource Uses. Describes land use and how resources (e.g., surface water) will be addressed.

Section 7 - Summary of Site Risks. Discusses the human health risk assessment for OU2, including risk estimates.

Section 8 - Remedial Action Objectives and Remedial Goals. Discusses the goals and objectives developed by EPA to protect human health and the environment at the Libby site in general and OU2 in particular.

Section 9 - Description of Alternatives. Describes the remedial alternatives developed and evaluated in the FS, including a description of remedy components, common elements and distinguishing features, and expected outcomes.

Section 10 - Comparative Analysis of Alternatives. Presents a summary of the remedial alternatives that were retained for detailed analysis against the two threshold criteria and five balancing criteria in the FS.

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Section 11 - Principal Threat Wastes. Identifies the principal threat waste at OU2 and discusses how the selected remedy will prevent exposure to it.

Section 12 – Selected Remedy. Provides a detailed description of the selected remedy, including its components, cost, expected outcomes, performance standards, and compliance with EPA’s environmental justice mandate.

Section 13 –Statutory Determinations. Describes how the selected remedy is protective of human health and the environment, complies with or appropriately waives applicable or relevant and appropriate requirements (ARARs), is cost effective, and utilizes permanent solutions and alternative treatment technologies or resource recovery technologies to the maximum extent practicable.

Section 14 – Documentation of Significant Changes. Confirms that no significant changes were made to the Preferred Remedy that was outlined in the proposed plan prior to its becoming the selected remedy described in this ROD.

Section 15 – References. Provides a list of references cited in the ROD.

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2-1

Section 2 Site History and Response Activities

2.1 Site Background and History

Numerous hard rock mines have operated in the Libby area since the 1880s, but the dominant impact to human health and the environment in Libby has been from vermiculite mining and processing. Prospectors first located vermiculite deposits in the early 1900s on Rainy Creek northeast of Libby. Edward Alley, a local rancher, was also a prospector and explored the old gold mining tunnels and digs in the area.

Reportedly, while exploring tunnels in the area, he stuck his miner's candle into the wall to chip away some ore samples. When he retrieved his candle, he noticed that the vermiculite around the candle had expanded, or “popped,” and turned golden in color.

In 1919 (Exhibit 2-1), Alley bought the Rainy Creek claims and started the vermiculite mining operation called the “Zonolite Company.” While others thought the material was useless, he experimented with it and discovered it had good insulating qualities. Over time, vermiculite became a product used in insulation, feed additives, fertilizer/soil amendments, construction materials, absorbents, and packing materials. Many people used vermiculite products for insulation in their houses in and around the Libby site and soil additives in their gardens. In 1963, Grace bought the mine and associated processing facilities and operated them until 1990.

Operations at the mine included blast and drag-line mining and milling of the ore.

Dry milling was done through 1985, and wet milling was done from 1985 until closure in 1990. After milling, concentrated ore was transported down Rainy Creek Road by truck to a screening facility (known today as the former Screening Plant) adjacent to Highway 37, at the confluence of Rainy Creek and the Kootenai River. Here the ore was size-sorted and transported by rail or truck to processing facilities in Libby and nationwide. At the processing plants, the ore was expanded or “exfoliated” by rapid heating, then exported to market via truck or rail. Historic maps show the location of the “Zonolite Company” processing operation at the edge of the lumber mill, near

Exhibit 2-1. History of Mining Activities Relevant to OU2

Section 2 Site History and Response Activities

2-2 present day Libby City Hall. This older processing plant was taken off line and demolished sometime in the early 1950s. The other processing plant (known today as the former Export Plant – OU1), was located near downtown Libby near the Kootenai River and Highway 37. Expansion operations at the site ceased sometime prior to 1981, although existing site buildings were still used to bag and export milled ore until 1990.

After operations ceased, Grace completed reclamation of the vermiculite mine. Reclamation included demolition of existing facilities and standard land recontouring and revegetation. The former Screening Plant was sold and converted into a nursery and was used for that purpose until 2000.

Over the course of Grace’s operation in Libby, invoices indicate shipment of nearly 10 billion pounds of vermiculite from Libby to processing centers and other locations. Most of this was shipped and used within the United States. Nearly all of this material ended up in a variety of commercial products that were marketed and sold to millions of consumers. The following subsections describe the historic, current, and anticipated future use of each subarea of OU2.

2.1.1 Former Screening

Plant (Subarea 1)

The former Screening Plant is located approximately 5 miles northeast of Libby on the east side of the Kootenai River (Exhibit 2-2). The area is approximately 21 acres in size, and is bordered by Highway 37 to the northeast, the privately owned property to the southeast, Flyway property to the south, and the Kootenai River to the west. From 1975 to 1990, the Screening Plant was used by Grace to screen mined vermiculite by size and grade. The vermiculite was transported from the mine to the site by truck, sorted, and bulk stored in two sheds at the facility. The vermiculite was then loaded onto a conveyor system and transported across the Kootenai River to a conveyor unloading station. Once the vermiculite was transported across the river, it was either trucked to the local export plant (OU1) for

Exhibit 2-2. OU2 Site Layout

2-3 processing and shipping or loaded onto rail cars for transportation and distribution to expansion plants outside of Libby.

From 1993 to 1999, the former Screening Plant was used as a fully-operational retail nursery (Raintree Nursery) business where plants, flowers, and trees were grown, stored, and sold. Related plant-care items were also stored and sold at the nursery.

The owners of the property lived on the site in a one-story structure that served both as an office and a residence. The largest structure on the property was referred to as the long shed. Approximately one-third of the long shed was used to store nursery supplies, tools, and equipment for the nursery business; the remaining two-thirds were leased to outside parties for storing recreational vehicles, trailers, boats, automobiles, and other items. Five greenhouses were used for growing plants, flowers, and shrubs, and a number of smaller buildings and support structures were used in the nursery operation. Two reinforced concrete tunnels were used to grow mushrooms that were shipped to the Far East for use as medical treatments. A number of steel tanks, hoppers, silos, and other remnants of the former mining operations at the former Screening Plant were stored at the site.

Due to the LA contamination associated with vermiculite from the Libby mine, the former Screening Plant has undergone extensive investigation and removal actions since EPA began emergency response activities in Libby in 1999. The property is currently privately owned and is being used for residential purposes. It is anticipated that the property will continue to be used for residential and/or commercial purposes.

2.1.2 Flyway (Subarea 2)

Currently owned by Kootenai Development Corporation (KDC) (a subsidiary of Grace), the area commonly referred to as the Flyway is comprised of approximately 19 acres northeast of Libby, immediately south of the former Screening Plant and the privately-owned parcel (Exhibit 2-2). The Flyway is bounded by Highway 37 to the northeast, a residential subdivision (River Runs through It) to the south, the Kootenai River to the southwest, and the former Screening Plant and private property to the north. The Flyway is accessed through a gated entrance to the adjacent private property off Highway 37. For the purpose of this report, the Flyway area includes the Highway 37 right-of-way, which is adjacent to the west side of Highway 37. The right-of-way is used and maintained by the Montana Department of Transportation

(MDT).

The Flyway housed a pump that was used during vermiculite mining operations to convey water from the Kootenai River to the mine site. The pump house, located close to the Kootenai River, has since been abandoned and the pump is no longer functional. The interior insulation of this metal structure was removed and all parts of the building were washed. The empty structure was left on-site for possible future use.

2-4

In 1999, when EPA first visited the property, the Flyway was found to contain several vermiculite piles. One portion of the property had been covered with imported fill and it was suspected that vermiculite-containing material had been moved from the former Screening Plant and used as fill to level parts of the Flyway where drainages existed. Following investigation work performed by EPA as part of the Libby emergency response, a portion of the Flyway was remediated in 2001 by Grace at the direction of EPA. In 2003, remediation at the site was performed by EPA, in 2004 additional remediation was performed by Grace at the direction of EPA, and in 2005, the Highway 37 right-of-way was remediated by EPA. Details of investigation and remediation activities conducted at the Flyway are provided in Section 2, of this report. The Flyway is currently vacant, undeveloped land. At this time, there are no plans to develop this property by the owners.

2.1.3 Private Property (Subarea 3)

The private property of Subarea 3 consists of an approximate 1-acre parcel situated between the former Screening Plant and the Flyway, and bordered by Highway 37 to the northeast (Exhibit 2-2).