AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule; notice of intent.

SUMMARY:

The Environmental Protection Agency (EPA) Region 8 is issuing a Notice of Intent to Delete the surface and unsaturated subsurface soils outside of the 4.5 acre Treated Soils Area of the Idaho Pole Company Superfund Site (Site) located in Bozeman, Gallatin County, Montana, from the NPL, promulgated pursuant to section 105 of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended, is an appendix of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The EPA and the State of Montana, through the Montana Department of Environmental Quality (MDEQ), have determined that all appropriate response actions at these identified media under CERCLA, other than operation and maintenance, monitoring and five-year reviews have been completed. However, this deletion does not preclude future actions under Superfund.

This partial deletion pertains to the surface and unsaturated subsurface soils remedy component outside of the 4.5 acre Treated Soils Area of the Idaho Pole Company Superfund Site. The 4.5 acre Treated Soils Area is identified on the survey map in the docket and is the location where all treated soils were placed after on-site treatment. The groundwater and saturated subsurface soils within the historic groundwater table, and the Site's sediments are not being considered for deletion as part of this action.

DATES:

Comments must be received by August 19, 2019.

ADDRESSES:

Submit your comments, identified by Docket ID no. EPA-HQ-SFUND-1986-0005, by one of the following methods:

• https://www.regulations.gov. Follow on-line instructions for submitting comments. Once submitted, comments cannot be edited or removed from Regulations.gov. The EPA may publish any comment received to its public docket. Do not submit electronically any information you consider to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Multimedia submissions (audio, video, etc.) must be accompanied by a written comment. The written comment is considered the official comment and should include discussion of all points you wish to make. The EPA will generally not consider comments or comment contents located outside of the primary submission (i.e. on the web, cloud, or other file sharing system). For additional submission methods, the full EPA public comment policy, information about CBI or multimedia submissions, and general guidance on making effective comments, please visit https://www.epa2.gov/​dockets/​commenting-epa-dockets.
• Email: hoogerheide.roger@epa.gov.
• Mail: Roger Hoogerheide, Remedial Project Manager; U.S. EPA Montana Office; Federal Building, Suite 3200; 10 West 15th Street; Helena, MT 59626.
• Hand delivery: U.S. EPA Montana Office; Federal Building, Suite 3200; 10 West 15th Street; Helena, MT 59626. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information by calling 406-457-5046.

Instructions: Direct your comments to Docket ID no. EPA-HQ-SFUND-1986-0005. The EPA's policy is that all comments received will be included in the public docket without change and may be made available online at http://www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through http://www.regulations.gov or email. The http://www.regulations.gov website is an “anonymous access” system, which means the EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an email comment directly to the EPA without going through http://www.regulations.gov, your email address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the internet. If you submit an electronic comment, the EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If the EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, the EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses.

Docket: All documents in the docket are listed in the http://www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in the hard copy. Publicly available docket materials are available either electronically in http://www.regulations.gov or are available electronically or in hard copy at: U.S. EPA Montana Office, Federal Building, Suite 3200, 10 West 15th Street, Helena, MT 59626, (406) 457-5046, Hours: Mon.-Fri. 8 a.m. to 5 p.m.; and the Bozeman Public Library, 626 East Main Street, Bozeman, MT 59715, (406) 582-2400, Hours: (Library hours vary).

FOR FURTHER INFORMATION CONTACT:

Roger Hoogerheide, Remedial Project Manager, 8SEM-RBS, U.S. EPA, Region 8—Montana Office, 10 W 15th St., Suite 3200, Helena, Montana 59626, (406) 457-5031 or 1-866-457-2690, extension 5031, hoogerheide.roger@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction

II. NPL Deletion Criteria

III. Deletion Procedures

IV. Basis for Intended Partial Site Deletion

I. Introduction

The EPA announces its intent to delete the surface and unsaturated subsurface soils of the Idaho Pole Company Superfund Site (Site) outside of the 4.5 acre Treated Soils Area, from the National Priorities List (NPL) and request public comment on this proposed action. The NPL constitutes Appendix B of 40 CFR part 300 which is the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), which the EPA promulgated pursuant to section 105 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) of 1980, as amended. The EPA maintains the NPL as those sites that appear to present a significant risk to public health, welfare, or the environment. Sites on the NPL may be the subject of remedial actions financed by the Hazardous Substance Superfund (Fund). The EPA proposed the facility for listing on the NPL in 1984, 29 FR 40320 (Oct. 15, 1984). The listing was final in 1986, 51 FR 21054 (June 10, 1986).

This partial deletion of the surface and unsaturated subsurface soils totaling approximately 82 acres at the Idaho Pole Company Superfund Site is proposed in accordance with 40 CFR 300.425(e) and is consistent with the Notice of Policy Change: Partial Deletion of Sites Listed on the National Priorities List. 60 FR 55466 (Nov. 1, 1995). As described in 300.425(e)(3) of the NCP, a portion of a site deleted from the NPL remains eligible for Fund-financed remedial action if future conditions warrant such actions. Any remaining contaminated saturated soils, sediments and groundwater at the Idaho Pole Company Superfund site as well as the 4.5 acres within the Treated Soils Area will remain on the NPL and are not subject to this partial deletion action.

The EPA will accept comments on the proposal to partially delete this site for thirty (30) days after publication of this document in the Federal Register.

Section II of this document explains the criteria for deleting sites from the NPL. Section III discusses procedures that the EPA is using for this action. Section IV discusses the response actions that have addressed the surface and unsaturated subsurface soils of the Idaho Pole Company Superfund Site and demonstrates how it meets the deletion criteria.

II. NPL Deletion Criteria

The NCP establishes the criteria that the EPA uses to delete sites from the NPL. In accordance with 40 CFR 300.425(e), sites may be deleted from the NPL where no further response is appropriate. In making such a determination pursuant to 40 CFR 300.425(e), the EPA will consider, in consultation with the State, whether any of the following criteria have been met:

i. Responsible parties or other persons have implemented all appropriate response actions required;

ii. All appropriate Fund-financed response under CERCLA has been implemented, and no further response action by responsible parties is appropriate; or

iii. The remedial investigation has shown that the release poses no significant threat to public health or the environment and, therefore, the taking of remedial measures is not appropriate.

Pursuant to CERCLA section 121(c) and the NCP, the EPA conducts five-year reviews to ensure the continued protectiveness of remedial actions where hazardous substances, pollutants, or contaminants remain at a site above levels that allow for unlimited use and unrestricted exposure. The EPA conducts such five-year reviews even if a site is deleted from the NPL. The EPA may initiate further action to ensure continued protectiveness at a deleted site if new information becomes available that indicates it is appropriate. Whenever there is a significant release from a site deleted from the NPL, the deleted site may be restored to the NPL without application of the hazard ranking system.

III. Deletion Procedures

The following procedures apply to deletion of the surface and unsaturated subsurface soils of the Site:

(1) The EPA consulted with the State before developing this Notice of Intent for Partial Deletion.

(2) The EPA has provided the state 30 working days for review of this notice prior to publication of it today.

(3) In accordance with the criteria discussed above, the EPA has determined that no further response is appropriate.

(4) The State of Montana, through the MDEQ, has concurred with the deletion of the surface and unsaturated subsurface soils of the Idaho Pole Company Superfund Site, from the NPL.

(5) Concurrently, with the publication of this Notice of Intent for Partial Deletion in the Federal Register, a notice is being published in The Bozeman Daily Chronicle. The newspaper notice announces the 30-day public comment period concerning the Notice of Intent for Partial Deletion of the Site from the NPL.

(6) The EPA placed copies of documents supporting the proposed partial deletion in the deletion docket, made these items available for public inspection, and copying at the Site information repositories identified above.

If comments are received within the 30-day comment period on this document, the EPA will evaluate and respond accordingly to the comments before making a final decision to delete the surface and unsaturated subsurface soils outside of the 4.5 acre Treated Soils Area. If necessary, the EPA will prepare a Responsiveness Summary to address any significant public comments received. After the public comment period, if the EPA determines it is still appropriate to delete the surface and unsaturated subsurface soils of the Idaho Pole Company Superfund Site outside of the 4.5 acre Treated Soils Area, the Regional Administrator will publish a final Notice of Partial Deletion in the Federal Register. Public notices, public submissions and copies of the Responsiveness Summary, if prepared, will be made available to interested parties and included in the Site information repositories listed above.

Deletion of a portion of a site from the NPL does not itself create, alter, or revoke any individual's rights or obligations. Deletion of a portion of a site from the NPL does not in any way alter the EPA's right to take enforcement actions, as appropriate. The NPL is designed primarily for informational purposes and to assist EPA management. Section 300.425(e)(3) of the NCP states that the deletion of a site from the NPL does not preclude eligibility for future response actions, should future conditions warrant such actions.

IV. Basis for Intended Partial Site Deletion

The following information provides the EPA's rationale for deleting the surface and unsaturated subsurface soils outside of the 4.5 acre Treated Soils Area of the Idaho Pole Company Superfund Site from the NPL.

Site Background and History

The Idaho Pole Company Superfund Site, CERCLIS ID MTD00623276, is located near the northern limits of Bozeman, Gallatin County, Montana. The Site occupies approximately 87 acres in the east half of Section 6 and the west half of Section 5, Township 2S, Range 6E of Gallatin County. The Site is bounded by the Montana Rail Link (MRL) railroad tracks to the south, L Street to the west and Rocky Creek to the east and north of the Site. Interstate Highway 90 (I-90), Bohart Lane and Cedar Street traverse the Site in an east-west direction.

The four parcels south of I-90, north of the MRL railroad tracks and east of L Street are part of this partial deletion. The four parcels are owned by the Idaho Pole Company (IPC) and total approximately 40 acres. These parcels contain the groundwater recovery system building and associated extraction and injection galleries, a log cabin structure that was historically used by the site manager but is currently unoccupied, and an office building. The remaining area is an open field. The four parcels are within Bozeman's city limits and are currently zoned for commercial/industrial use. Cedar Street transects this section of the Site. A portion of two of these parcels contains the 4.5 acre Treated Soils Area. This is where treated soils that do not allow for unlimited use and unrestricted exposure have been placed and a Notice of Institutional Controls has been filed on the deed with Gallatin County Clerk and Recorder restricting excavation and construction in this area without specific approval from the State of Montana and the EPA.

The Idaho Pole Company also owns the parcel immediately north of Bohart Lane and east of L Street which is part of this partial deletion. This parcel is currently fenced to restrict access since there was an interceptor trench that was used to historically recover wood treating fluids. Product that accumulated in the trench was removed from the trench using absorbent pads, as needed. Operation of the trench ceased in October 2015 after several years where no product was recovered, and the trench was closed per the EPA approved Trench Closure Work Plan. The fence is not needed for the remedy and can be taken down to facilitate redevelopment of the property. There are no structures on this property. This approximately seven-acre parcel is identified as the Pasture Area in site documents and is within Bozeman city limits. The property is zoned for commercial/industrial use and there is a potential to place commercial structures on this property in the future.

Approximately eighteen additional acres on three parcels owned by IPC north of Bohart Lane, south of Rocky Creek and east and west of L Street are also part of this partial deletion. There are currently no structures on these properties and these parcels are occasionally used by nearby residents as pasture. These parcels are outside of Bozeman city limits in unincorporated Gallatin County and are zoned rural residential.

In addition to property owned by IPC, approximately seven acres is owned by Northwestern Energy (formerly Montana Power Company) including the East Gallatin Substation. This parcel is immediately north of Bohart Lane and east of the Pasture Area parcel. The East Gallatin Substation was constructed in the mid-1970's and serves the northeast side of Bozeman.

Another approximately fifteen acres includes the portions of I-90, Cedar Street, and Bohart Lane that transect the Site as well as the right away associated with these roads. Privately-owned land north and east of Rocky Creek and west of L Street are only included in the groundwater portion of the Site and are not part of this partial deletion. Interstate Highway 90 was constructed through the property north of the facility from 1967 to 1969. Historically, the land now occupied by 1-90 and the area northeast of 1-90 to Rocky Creek was predominantly used for residential and ranch purposes.

Between the late 1800s and early 1940s, the Northern Pacific Railroad Company operated a five-stall roundhouse south of Cedar Street and east of L Street that was used for light maintenance and to house helper engines that were used to pull and push trains up and down Bozeman Pass. Modifications to the roundhouse were periodically completed to accommodate larger helper engines that came into service. The roundhouse was considered obsolete with the development of diesel engines in the 1930s that had sufficient power to traverse Bozeman Pass without helper engines and the roundhouse was abandoned in the early 1940s.

The IPC wood treating facility began operations in 1945 using creosote to preserve wood. The creosote was mixed with a petroleum distillate and heated in vats prior to treatment. Creosote contains several larger hydrocarbon molecules (polynuclear aromatic hydrocarbons (PAHs)) which are identified as contaminants of concern at the Site.

Lodgepole pine and cedar (white wood) poles were brought to the Site by rail and truck and stored until treated. White wood was stored near the former roundhouse area as well as between the treatment facilities and the MRL railroad tracks awaiting treatment. The wood treatment process was initiated via a customer order. Prior to treatment, the bark was removed from the poles and excess bark was stored in piles on-site at the east side of the property on both the north and south sides of Cedar Street.

In the early days of Site operations, treatment consisted of immersion of the end of the poles into a butt vat of heated creosote solution. This was later extended to full length pole treatment with the installation of a full-length vat in 1952. There was also a drying area on-site where treated poles were stored temporarily prior to shipment off-site. Since most orders were custom orders, treated poles only stayed on-site for a few days before transport to the customer.

In 1952, IPC switched to pentachlorophenol (PCP) for wood treatment. Initially, any remaining creosote was cycled in with PCP rather than disposed on-site since there were few customer concerns about the color of the treated wood. Pentachlorophenol continued to be used until wood treatment operations ceased in 1997. Pentachlorophenol is a known carcinogen and is also identified as a contaminant of concern at the Site.

The PCP was brought to the Site in bulk as a solid and was diluted as a 5% solution in a carrier oil and heated in vats prior to wood treatment. Commercial grade PCP usually contains about 86% PCP purity and 14% other impurities such as chlorophenols and dioxins/furans. The other chlorophenols include compounds such as tetrachlorophenol, trichlorophenol, and dichlorophenol. Dioxins/furans produced during the manufacturing of PCP are the result of improper combustion.

In 1975, a pressurized heated retort was added for treating full length poles and placed in the Pressure Plant. The full-length vat used to treat full-length poles that was installed in 1952 was taken out of service in 1979 and demolished in 1981. Wood treating operations continued with the pressurized heated retort and the butt vat until 1997 when wood-treating operations ceased.

The full-length vat that was decommissioned in 1979 had corroded on the bottom and the vat leaked an unknown amount of wood treating fluid into the underlying soil and groundwater for an undetermined amount of time resulting in the majority of releases observed at the Site. System operations also resulted in the occasional spilling of heated wood treating fluids on nearby soils around treatment facilities. All treatment operations described above occurred around the 4.5 acre Treated Soils Area located south of I-90.

In 1978, the Montana Department of Fish, Wildlife and Parks notified the Montana Department of Health & Environment (MDHES) of a suspected release of oily wood treating fluid from the plant. MDHES found evidence of a release in ditches near the facility and near Rocky Creek. Consequently, MDHES issued a compliance order on September 29, 1978, notifying IPC of statutory violations and directing the company to stop uncontrolled releases and to clean up spilled treating fluid. Between 1978 and 1980, IPC installed an interceptor trench and drain that ran parallel to I-90 to collect non-aqueous phase liquid (NAPL) on the groundwater surface. In 1984, IPC hired a consultant to investigate soil, sediment, surface water, and groundwater contamination. The results of the investigation, which was conducted without MDHES or EPA oversight, are presented in a 1985 report. The EPA proposed the facility for listing on the NPL in 1984, 29 FR 40320 (Oct. 15, 1984). The listing was final in 1986, 51 FR 21054 (June 10, 1986).

Remedial Investigation and Feasibility Study (RI/FS)

In March 1989, MDHES requested and received the lead agency role for a fund-financed RI/FS for the Site. The RI defined the nature and extent of contamination and provided data to complete the baseline Human Health and Ecological Risk Assessments. Contaminated surface soils were identified around the treatment facilities, north and south of Cedar Street, near the former roundhouse and in the Pasture Area. Contamination of the groundwater saturated subsurface soils occurred within the bounds of the 6.7-acre wood treating NAPL contamination area identified in Figure 5-3 of the RI Report. This subsurface NAPL resulted in the smearing of oily wood treating fluid in the subsurface during the seasonally fluctuating groundwater table. At high water table conditions, the oily wood treating fluid expressed near the ground surface in the Pasture Area north of I-90, resulting in isolated pockets of wood treating fluid in the subsurface soils.

Upon completion of the RI Report, the Feasibility Study (FS) commenced. The primary objective of the FS was to provide sufficient information to support an informed risk management decision to select the most appropriate cleanup remedy for the IPC Site. The soil component of the remedy identified excavation and on-site treatment of accessible soils as the most appropriate remedy. Inaccessible soils (saturated subsurface soils, soils under I-90 and active facility operations) would be addressed as part of the groundwater remedy.

For human health protection, the remedial action objectives identified in the FS for soil are to:

• Prevent excess incidence of cancer risks from exceeding 1 in 10,000 following lifetime direct contact with, and ingestion of, soils contaminated with carcinogenic contaminants of concern (CoCs);
• Prevent ingestion of/direct contact with soils having noncarcinogens at levels which exceed the reference doses; and
• Prevent excess incidence of cancer risks from exceeding 1 in 10,000 following inhalation of carcinogenic CoCs at a lifetime of exposure.

For environmental protection, the remedial action objective for soil is to:

• Prevent migration of contaminated leachate that would result in groundwater contamination in excess of the proposed maximum contaminant levels (MCLs). (Proposed MCLs are To Be Considered as Applicable Relevant and Appropriate Requirements).

Selected Remedy

Following issuance of a Proposed Plan, the EPA released a Record of Decision (ROD) in 1992. A remedial alternative for soil and groundwater that is protective of human health and the environment was selected. The COCs identified in the ROD are PCP, PAHs, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (dioxins/furans) which are reported as a toxicity equivalent value of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD TEQ)). One Operable Unit (OU01) was established for the Site and included the soil and groundwater component. The EPA's remedy selection was based on the assumption that IPC would continue its commercial operations, limiting access to soils underlying operating structures.

The major components of the selected remedy that addressed contaminated surface and unsaturated subsurface soils include:

• Excavation and surface land biological treatment on-site of accessible contaminated soils from the Pasture Area and the area between Cedar Street and I-90 including ditch sediments or bottoms, and the former roundhouse area;
• Hot water and steam flushing of inaccessible soils underlying the active pole plant facility and I-90 in order to recover hazardous substances;
• Separation and disposal of oily wood treating fluid extracted from soils; and
• Implement land use and deed restrictions (Institutional Controls) to preserve the integrity of the remedy.

The ROD established performance standards deemed protective of human health and the environment for both soils and groundwater. Site specific soil performance standards of known or suspected carcinogenic contaminants (PCP, TCDDs, and Total class B2 PAHs) were developed based on a cancer risk of 1.0 × 10⁻⁶. Noncancer contaminant (Total class D PAHs) soil performance standards were developed based on a noncancer health hazard quotient of 0.1. Soil performance standards also assumed future commercial/industrial use for the properties south and immediately north of I-90. The soil performance standards established in the ROD are:

• PCP <48 milligrams/kilogram (mg/kg)
• Total class B2 PAHs (carcinogen or suspected carcinogen) <15 mg/kg
• Total class D PAHs (non-carcinogen) <145 mg/kg
• TCDD TEQ (dioxin toxicity equivalent) <1.0 × 10⁻³ mg/kg (1.0 µg/kg)

The NAPL contaminated area was also revised in the ROD to cover 7.4 acres and assumed 39,304 cubic yards of contaminated soil exceeded soil performance standards. The ROD also assumed that the soil component and the groundwater component of the selected remedy would operate simultaneously to eliminate the PAHs, PCP and TCDDs that may continue to migrate downward from the unsaturated soils to the saturated subsurface soils and groundwater, and to remove as much of the contamination that is already present in the saturated subsurface soils and groundwater to the extent practicable.

The EPA initiated negotiations with the potentially responsible parties (PRPs) for implementation of the remedy after issuance of the ROD. The PRPs identified were the Idaho Pole Company and Burlington Northern Santa Fe Railway Company (BNSF), as successor to the Northern Pacific Railway Company. The negotiations were unsuccessful and consequently the EPA issued a Unilateral Administrative Order for Remedial Design/Remedial Action (EPA Docket No. CERCLA VIII-93-26) with an effective date of August 26, 1993. Remedial Design commenced on February 23, 1994 with EPA approval of the Remedial Design Work Plan.

The findings of additional studies conducted during the Remedial Design included modifications to the soil remedy design which were not included in the 1992 ROD. These modifications were made through an Explanation of Significant Difference (ESD) in 1996 and are listed below.

• Based on the subsurface conditions under I-90 and the Pressure Plant, the EPA and MDEQ, formerly MDHES, determined that the hot water/steam flushing system called for in the ROD could not be implemented. These subsurface conditions included the Site geology, obstructions under the Pressure Plant foundation, and less oily wood-treating fluid than originally anticipated in the ROD. The EPA and MDEQ approved an alternative plan that increased the area within which soils were excavated by adding the accessible plant area soils and Cedar Street soils that exceeded the PCP performance standard of 48 mg/kg for soils. Soil flushing with ambient temperature water mixed with nutrients underneath the plant structures and I-90 would be designed as part of the groundwater remedy.
• Closer evaluation of the existing and additional data collected post-ROD indicated that the ROD cleanup levels were not exceeded in the East Gallatin Substation ditch. Therefore, no ditch sediments needed to be excavated.
• A Land Treatment Unit (LTU) was to be constructed in the southeast corner of the pole storage yard and the excavated soil from all targeted areas of the Site were to be screened to remove rocks and placed directly on the LTU. The total soil depth on the LTU was to be less than two feet. The LTU would operate to treat the soils to approximately one foot in depth and the soils would be removed when ROD performance standards were met.
• The treated soils may be used for fill material on excavated areas of the Site. If the soil contains other contaminants (e.g., dioxins/furans) that exceed the ROD performance standards after treatment, the treated soil will be isolated from groundwater; will be covered with a minimum of twelve inches at the surface to prevent direct contact and Institutional Controls on future land use will be required. A detailed closure plan for the LTU will be developed when soil monitoring results indicate that the cleanup levels for PCP and PAHs have been achieved. The closure plan will identify the areas to be backfilled with the treated soil and will specify separation from groundwater and the depth of cover required. The plan will also identify the specific Institutional Controls to be implemented on the Site.

In the fall of 1997, IPC announced that it would terminate wood treatment operations. This had the potential to change the scope of the remedial action which required another ESD. The significant difference between the remedy described in the 1992 ROD and in the 1998 ESD was that the existing plant structures, including concrete pads, piping, vaults, etc., preventing access to contaminated soil, were to be demolished and disposed of in accordance with State of Montana and EPA requirements. Contaminated soils underlying these areas were to be excavated and treated in the LTU like the accessible soils elsewhere at the facility had been treated to date.

Response Actions

The soil remedy identified in EPA's ROD and supplemented in the subsequent ESDs was implemented between July 1995 and October 2002. The remedy included construction of a lined LTU and a retention pond to collect any runoff from the LTU; excavation of soils in the accessible areas of the Site, as well as de-rocking and transportation of excavated soils to the LTU. The LTU was constructed per EPA approved plans and specifications. The soils were treated in the LTU until ROD performance standards for PCPs and PAHs were met at which time they were placed in the excavated areas on-site above historic high groundwater levels and clean soil placed on top. The ROD contemplated pre-treatment of the excavated soils to remove NAPL prior to placement in the LTU. However, this step was determined to not be necessary because there was insufficient NAPL in the excavated soil to remove.

Approximately 14,000 cubic yards of contaminated soil were placed in the LTU in 1995. The soils were excavated from six areas at the Site: The Pressure Plant Area, beneath Cedar Street, the Barkfill Area, the Roundhouse Area, the Cedar Street Ditch and the Pasture Area. The majority of soils in the Barkfill and Pasture Areas were contaminated by NAPL smearing of the saturated subsurface soils. Clean overburden above the saturated soils was stripped off in these locations and stockpiled for use as backfill. The exposed NAPL impacted silty clay layer located just below and above the water table was then excavated and placed in the LTU. Excavated soils were treated in the LTU by tilling, irrigation and nutrient addition with a retention pond collecting any excess water, which was subsequently treated in the groundwater recovery system. Prior to placement of contaminated soils into the LTU, the excavated soils were de-rocked, the rock cleaned and stockpiled for later use. The clean overburden acquired during the excavation of the Barkfill and Pasture Areas was used as fill in the Pasture Area, the Roundhouse, Cedar Street and Cedar Street ditch excavations so that there were no open excavated areas filled with groundwater during soil treatment in the LTU except near the facilities.

The first phase of soils excavated in 1995 were treated in two 10-inch-thick lifts. The first lift included approximately 4,900 cubic yards which met ROD performance standards for PCP and PAH by 1998. A workplan to remove the upper lift from the LTU was approved by the EPA on March 2, 1999. Removal and placement of these treated soils in the Barkfill and Pressure Plant Areas was completed by June 1999. Prior to placement of treated soils in the Barkfill and Pressure Plant Areas, the stockpiled clean rock was used as backfill for the excavation. Imported clean borrow was also placed on top of the rock and compacted prior to placement of treated soils in the excavated pits since the majority of clean overburden was used to backfill several unsecured excavation areas in 1995.

After the first lift was removed, an additional 5,000 cubic yards of impacted soil under the Pressure Plant was excavated. These soils were loaded on the LTU for treatment in 1999 after the remaining buildings and infrastructure associated with wood treatment operations were demolished and properly disposed off-site. Soils were managed in the LTU for a few more years before ROD performance standards were achieved.

An LTU Closure Work Plan was submitted to the EPA in February 2002 and was approved in July 2002. The LTU closure activities were conducted in accordance with the approved LTU Closure Work Plan. Closure activities were based on the September 2000 excavated soil analytical results being below the ROD soil treatment goals for PCP and PAHs. Dioxin/furan levels calculated as TCDD TEQ remained above the ROD performance standards in the treated soils. Sample results ranged from 1.0 to 5.0 microgram/kilogram (µg/kg) expressed as TCDD TEQ. The 1996 ESD specified that the treated soils may be used for fill material on excavated areas of the Site. If the soil contains other contaminants (e.g., dioxins/furans) that exceed the ROD performance standards after treatment, the treated soil would be isolated from groundwater and covered with a minimum of twelve inches at the surface to prevent direct contact. Institutional Controls on future land use would also be implemented.

The LTU was subsequently decommissioned and closed in accordance with the EPA-approved closure plan. The construction, operation and closure of the LTU is documented in the LTU Closure Completion Report. The LTU liner was taken out, rinsed and disposed of off-site. The clean soils that were excavated to construct the berm around the LTU and retention pond were used to close the LTU. These soils were graded flat upon removal of the LTU leachate collection system, filter fabric and liner. Fifteen thousand cubic yards of soil used in the construction of the LTU were placed across the LTU area and re-contoured for drainage control, and future reuse of the location.

The majority of the approximately 41 acres south of I-90 was used to store whitewood prior to treatment. Therefore, a location south of the former Pressure Plant that was determined to be clean during the remedial investigation was identified as a suitable location to place the remaining treated soils from the LTU (plus an additional 5,240 cubic yards of drainage sand that was placed at the bottom of the LTU to facilitate drainage).

Two pits were excavated in an area south of the former Pressure Plant for placement of the treated soils and drainage sand. Treated soils were placed in these excavated areas above historic groundwater levels. After treated soil was placed in the pits, sand and filter fabric were placed in the Pit Area and compacted. A twelve to fifteen-inch cover of clean fill material was then placed over the Pit Area. Approximately 4,440 cys of clean fill material excavated originally from the Pit Area were placed as the final soil cover. The soil cover was placed to prevent direct contact risk with the treated soil as described in the Remedial Action Objectives. Cap thickness was verified with a pre and post excavation survey of the Pit Area.

While no samples were taken to confirm the concentrations in the soils used to cover the treated soils, the area south of the former pressure plant was used for whitewood storage and samples collected during the remedial investigation at surface and depth from test pits in the area showed these areas to be clean. As there is no record in the site file showing that samples of this overburden were analyzed for dioxins/furans, five-point composite surface soil samples were collected from the soil cover from four locations on-site in June 2018 and analyzed for dioxins/furans. The TCDD TEQs calculated for the four surface soil sample results ranged from 0.012 µg/kg to 0.570 µg/kg—below the ROD performance standard of 1.0 µg/kg.

While the ROD performance standards for PCP and PAHs were achieved through biological treatment, performance standards for dioxins/furans expressed as TCDD TEQs (dioxin toxicity equivalents) were not. Even though the TCDD TEQ concentrations in the treated soils exceed the soil performance standards established in the 1992 ROD, the soils remedy is protective of human health and the environment because no exposure pathways exist since the treated soils have been placed above historic groundwater levels; have clean soil on top as a cover; and Institutional Controls (ICs) discussed later are in place that restricts land use in the 4.5 acre Treated Soils Area.

Operation and Maintenance

No further or ongoing surface and unsaturated subsurface soil operation and maintenance activities are required other than maintaining ICs and ensuring that a protective cover remains over areas where treated soils have been placed. It is the responsibility of McFarland Cascade, the parent company of IPC, their successors and assigns to ensure that the integrity of the soil component of the remedial action is maintained as long as the treated soils at the Site do not allow for unlimited use and unrestricted exposure. Five composite samples were collected at depth from the treated soils area in October 2017 to determine if the treated soils met ROD performance standards for TCDDs. Samples collected at four of the five sample locations exceeded the ROD performance standards of 1.0 µg/kg. Values ranged from 0.69 µg/kg to 2.9 µg/kg. These results support the need to continue to have Institutional Controls and a protective cover in place to ensure that soil remedy remains protective of human health and the environment.

Institutional Controls

A Notice of Institutional Control was filed with the Gallatin County Clerk and Recorder in 2010 that applies covenants, conditions and restrictions that run with the land and are binding on IPC, their successors and assigns, and any subsequent interest owner of the property. These include restrictions on new construction and excavation on the 4.5-acre area where treated soils were placed. Restrictions on use of groundwater on all IPC property were also included as a restriction. These restrictions ensure protection of the integrity of the remedial actions. This notice and corresponding attachments are included with the property deed records and fulfills the land use restrictions specified in the 1992 ROD and 1996 ESD.

A Controlled Groundwater Use Area was created in 2001 under State law that includes the IPC Site and the nearby residential properties north of I-90, east and west of L Street and south and north of Rocky Creek. The purpose of the Controlled Groundwater Use Area designation is to prevent construction of new wells, where the consumption of groundwater may pose a threat to human health, and to protect the groundwater remedy.

Five-Year Reviews

The first five-year review of the remedial action was completed in September 2000. The results of this review noted that the remedies for soil were protective of human health and the environment because all accessible soils exceeding ROD performance standards had been excavated and placed in the LTU. At the time of the first review, the LTU had also successfully treated one lift, and the treatment of all of the contaminated soils was predicted to be complete within two years.

The second five-year review was completed in August 2005. The results of this review indicated that the soil remedy continues to be protective of human health and the environment. The soil component of the remedy achieved the performance standards for PCP and PAHs as specified in the 1992 ROD, and the LTU was dismantled and closed. Dioxin/furan levels expressed as TCDD TEQs (dioxin toxicity equivalent) remained above the ROD performance standards, but these soils were placed above the historic groundwater table and covered with a minimum of twelve inches of soil per the 1996 ESD. A deed notification was also filed was filed with Gallatin County in 2004 that placed use restrictions on those areas where waste was left in place above levels that allow for unlimited use and unrestricted exposure.

The third five-year review was completed in September 2010. The results of this review indicated that the remedies for soil continue to be protective of human health and the environment in the short-term. The remedy at the soils component currently protects human health and the environment because soils have been treated to ROD standards and placed back on-site with a protective cover of clean soil placed over these treated soils. However, in order for the remedy to be protective in the long-term, an enforceable Institutional Control needed to be placed on the property. Although a deed notification had been in place since 2004, it was determined to not be protective of the remedy. A Notice of Institutional Controls was filed with Gallatin County in September 2010 that follows Montana Code Annotated 76-7-201, and addressed the deficiencies identified in the previous deed notification.

The fourth five-year review was completed in August 2015. While a site-wide protectiveness determination could not be made due to insufficient data available to evaluate the groundwater remedy, there were no issues or recommendations in the five-year review related to the soil remedy. The additional data have since been collected and reviewed and an addendum to the five-year review was issued on March 11, 2019 that determined the remedy is protective of human health and the environment.

The next five-year review is scheduled to be completed in September 2020.

Community Involvement

Prior public participation requirements have been satisfied as set forth in CERCLA Section 113(k), 42 U.S.C. 9613(k), and CERCLA Section 117, 42 U.S.C. 9617. Major community involvement activities at the Site included establishing a local presence by meeting with property owners and concerned citizens. Outreach efforts included community interviews, fact sheets, public meetings, neighborhood meetings, public comment periods and website updates. The most recent fact sheet was sent out in November 2017 and the last public meeting was held in December 2017. The City and County Commissioners were briefed in December 2017 and the Gallatin City-County Board of Health was briefed in February 2018. The partial deletion of the surface and unsaturated subsurface soils component of the IPC Site was discussed at these meetings and presented in EPA's fact sheet.

Documents in the partial deletion docket that the EPA relied on for recommending the partial deletion from the NPL are available to the public in the information repositories, and a notice of availability of the Notice of Intent for Partial Deletion has been published in the Bozeman Daily Chronicle to satisfy public participation procedures required by 40 CFR 300.425(e)(4).

Determination That the Site Meets the Criteria for Deletion

The implemented soil remedy achieves the Remedial Action Objectives specified in EPA's 1992 ROD and the subsequent ESDs for all soil pathways of exposure. No further Superfund responses are needed to protect human health and the environment at the Site.

The NCP (40 CFR 300.425(e)) states that a portion of a site may be deleted from the NPL when no further response action is appropriate. The EPA, in consultation with the State of Montana, has determined that all required response actions have been implemented for the soil component of the remedy and no further response action by responsible parties is appropriate.

List of Subjects in 40 CFR Part 300

• Environmental protection
• Air pollution control
• Chemicals
• Hazardous waste
• Hazardous substances
• Intergovernmental relations
• Penalties
• Reporting and recordkeeping requirements
• Superfund
• Water pollution control
• Water supply

Authority: 33 U.S.C. 1321(d), 42 U.S.C. 9601-9657; E.O. 13626, 77 FR 56749, 3 CFR 2013 Comp., p. 306; E.O. 12777, 56 FR 54757, 3 CFR, 1991 Comp., p. 351; E.O. 12580, 52 FR 2923, 3 CFR, 1987 Comp., p. 193.