THIRD FIVE-YEAR REVIEW REPORTSARNEY FARM SUPERFUND SITEDUTCHESS COUNTY, NEW YORK

Prepared by

U.S. Environmental Protection AgencyRegion 2

New York, New York

September 2016

y: Date:

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~------~------Walter E. Mugdan, irectorEmergency and Remedial Response Division

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Five-Year Review Report

Table off Contents

I. Introduction 1

II. Site Chronology 1

III. Background 1 Site Location 1 Site Characteristics 1 Site Geology/Hydrology 2 History of Contamination 2 Initial Response 3 Remedial Investigation/Feasibility Study 3

IV. Remedial Actions 3 3

Remedy Selection 3 Remedial Action Implementation 3

7 Operations, Maintenance and Monitoring 7

V. Progress Since the Last Five-Year Review 8

VI. Five-Year Review Process 8 Administrative Components 8 Community Notification and Involvement 8 Document Review 8 Data Review 8 Site Inspection 9 Interviews 9 Institutional Controls Verification and Effectiveness 9

VII. Technical Assessment 9 Question A 9 Question B 9 Question C 10 Technical Assessment Summary 11

VIII. Issues, Recommendations and Follow-up Actions 11

IX. Protect!veness Statement 12

X. IMext Review 12

Attachments:

Figures

Figure 1 - Site Map Figure 2 - Site Plan Figure 3 - MW-7 1,2-DCA Figure 4 - MW-7 1,2-DCA Figure 5 - MW-9 1,2-DCA

Concentrations 2007-2015 Concentrations 1997-2015 Concentrations 2007-2015

Tables Table 1 Chronology of Site Events Table 2 Annual System Operations/O&M Costs Table 3 List of Documents Reviewed

Executive Summary

This is the third five-year review for the Sarney Farm Superfund site. The site is located in the Town/City of Amenia, Dutchess County, New York. The implemented remedies at the Sarney Farm Superfund site currently protect human health and the environment in the short term by controlling exposure pathways that could result in unacceptable risks. The levels of contaminants remaining in the soils are protective of the environment and human health. Institutional controls prohibiting the installation of on-site groundwater wells prevent the ingestion of contaminated groundwater are in place. The second five-year review indicated that additional measures may need to be taken to address the remaining contamination in the groundwater in order for the remedy to be protective in the long term. Data collected since the last five-year review indicate that contaminant levels in the groundwater are continuing to decline slowly, suggesting that restoration of the aquifer may not be possible under the framework of the existing remedy. A preliminary evaluation of additional treatment technologies did not indicate that alternative existing technologies would expedite the trajectory for restoration of the ground water. In order to ensure that the remedy will be protective in the long term, prior to the completion of the fourth five-year review, EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater. If it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site.

Five-Year Review Summary Form

Issues/Recommendations

OU(s) without Issues/Recommendations Identified in the Five-Year Review:

N/A

Issues and Recommendations Identified in the Five-Year Review:

OU(s): 3 Issue Category: Remedy Performance OU(s): 3

Issue: Contaminant levels in groundwater are declining more slowly than expected.

OU(s): 3

Recommendation: (1) EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater; if it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site. (2) Implement the additional sampling that EPA has directed the PRP to perform, which includes: additional sampling of Cleaver Swamp surface water and sediment, sampling for MNA parameters and additional sampling for 1,4-dioxane

Affect Current Protectiveness

Affect Future Protectiveness

Party Responsible

Oversight Party

Milestone Date

No Yes PRP EPA 11/11/2018

Protectiveness Statement(s)

Operable Unit: Protectiveness Determination: Addendum Due Date 1 Short-term Protective (if applicable):

N/A

Protectiveness Statement: The implemented remedies at the Sarney Farm Superfund site currently protect human health and the environment in the short term by controlling exposure pathways that could result in unacceptable risks. In order to ensure that the remedy will be protective in the long term, prior to the completion of the fourth five-year review, EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater. If it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site.

Sitewide Protectiveness Statement

Protectiveness Determination: Short-term Protective

Addendum Due Date (if applicable): N/A

Protectiveness Statement: The implemented remedies at the Sarney Farm Superfund site currently protect human health and the environment in the short term by controlling exposure pathways that could result in unacceptable risks. In order to ensure that the remedy will be protective in the long term, prior to the completion of the fourth five-year review, EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater; if it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site.

Five-Year Review Report

I introduction

This five-year review for the Sarney Farm Superfund site (site), located in the Town of Amenia, Dutchess County, New York, was conducted by United States Environmental Protection Agency (EPA) Remedial Project Manager Kevin Willis. The five-year review was conducted pursuant to Section 121 (c) of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended, 42 U.S.C. §9601 et seq. and 40 CFR 300.430(f)(4)(ii), and in accordance with the Comprehensive Five-Year Review Guidance, OSWER Directive 9355.7-03B-P (June 2001). The purpose of a five-year review is to assure that implemented remedies protect public health and the environment and function as intended by the decision documents. This report will become part of the administrative record for this site.

This is the third five-year review for this site. The triggering action for this review is the date of the last five-year review, July 1, 2011. EPA is the lead agency for this site. Operation and maintenance activities are being conducted by AMEC (formerly MACTEC) Consulting, Inc. for Pitney Bowes, Inc, the potentially responsible party (PRP).

The site consists of three operable units (OUs); OU1 (drum excavation), OU2 (soils treatment), OU3 (groundwater). OU1 and OU2 were completed in 1995 and 1997 respectively and did not leave any wastes in place that need to be addressed by this review. OU3 calls for monitoring of the groundwater until defined standards are achieved; at the time of remedy selection it was projected to take approximately 30 years to achieve groundwater restoration goals. OU3 is the subject of this five-year review.

BO. Site Chronology

Table 1, attached, summarizes the site-related events from discovery to the present.

DDL Background

Site Location

The site is located at 225 Benson Hill Road, in the Towns of Amenia and Dover, Dutchess County, New York. The site is bordered to the south by Benson Hill Road and residential properties, to the west by trees and agricultural areas, to the east by steeply sloping wooded areas, and to the northwest by the 25-acre Cleaver Swamp. (See Site Map)

Site Characteristics

The site topography is characterized as mountainous or hilly terrain with poorly to moderately well-drained soils. Limited flat terrain surrounds Cleaver Swamp.

Site Geology/Hydrology

The site is underlain by unconsolidated glacial drift deposits and consolidated limestone. Glacial drifts are differentiated into till, consisting of an unstratified unsorted mixture of clasts of many sizes. The Stockbridge limestone formation is medium to coarse-grained, partly calcific, partly dolomitic, and occasionally fossiliferous.

The region is dominated by a series of northeast/southwest oriented ridges separated by relatively flat valley floors. The site is located on the western flank of a secondary ridge approximately one mile west of East Mountain. Cleaver Swamp, a New York State wetland, is immediately north and west of the site.

Drainage from the site is primarily toward Cleaver Swamp and a down gradient stream south of the swamp. A minor drainage divide, located on the hill slope north of Benson Hill Road, imparts a localized southern vector for both surface runoff and overburden groundwater flow south of this divide. Groundwater levels, which peak between January and May, generally range from one to thirteen feet below grade.

Bedrock outcroppings are found on the wooded slopes, where the soil consists of well-drained, shallow sandy loam. Soil covering the open field area varies from shallow sandy loam, with bedrock outcroppings, to gravelly loam, and is well drained. The northern pasture contains poorly drained silt loam that is seasonally wet.

A geophysical investigation completed in 2000, which included seismic refraction, very low frequency and electromagnetic induction surveys, indicated the presence of a shallow bedrock valley with a minimum width of approximately 50 feet, trending northeast to southwest.

History of Contamination

A former owner was permitted to use a five-acre section of the property as a landfill for municipal wastes, but industrial and municipal wastes were disposed at locations throughout the site. Non-permitted hazardous wastes were disposed at the site from 1965 until 1969. The disposal operations were curtailed by the Dutchess County Department of Health (DCDH) in 1969. The site was subsequently purchased by the present owner in 1971. Groundwater contamination was found by the DCDH in 1980 and by New York State in 1982. The site was proposed to be included on the National Priorities List (NPL) in 1984 and was listed on the NPL in 1986.

Initial Response

EPA's Removal Program assessed the site in 1987. Based on sampling results, EPA initiated a removal/treatment action for organic contaminants at the site. EPA installed a treatment process consisting of an in-situ soil washing system for organic contamination at Areas 1 and 2. In addition, a french-drain system collected and treated leachate from the original dump site and areas to which contaminated leachate had migrated. This system remained active until the site remediation began.

Basis for Taking Action

EPA retained the services of Ebasco, Inc. to conduct a Remedial Investigation/Feasibility Study (RI/FS) at the site in 1988, which was completed in May 1990. As part of the RI/FS, EPA conducted a risk assessment.

The risk assessment looked at agricultural and potential residential land use at the Site. Under both scenarios several pathways (direct contact, inhalation and ingestion) were evaluated for exposure to: surface and subsurface soils; sediments and surface waters in the pond, streams, and wetland areas; and groundwater used for drinking and domestic purposes from the bedrock aquifer on the Site. Exposed populations included on-site and off-site residents, farm workers and construction workers. The risk assessment concluded that the majority of the risk was associated with ingestion of groundwater containing vinyl chloride and 1,2-dichloroethane. Direct contact with soils did not pose a risk, but there was risk associated with inhalation of volatile organic compounds (VOCs) emanating from subsurface soils into home basements if homes were built on Areas 2 and 4. No health risks were posed by exposure to the sediments and surface water of the ponds and stream associated with the site.

The ecological risk assessment concluded that the high functional ecological value of the marsh as wildlife habitat, in conjunction with relatively low levels (and numbers) of known contaminants, indicated that the adverse impacts caused by physical disturbance of the ecosystem (through remediation alternatives involving excavation of the wetlands) would significantly outweigh the potential benefits of subsequent surface water/sediment treatment.

IV. Remedial Actions

Remedy Selection

A Record of Decision (ROD) was signed in September 1990. The selected remedy included:

° Excavation of contaminated soil and buried drums;

• Transportation of contaminated drums to an off-site treatment and disposal facility;

• On-site low temperature thermal treatment of contaminated soil; • Grading of the excavated areas with the treated soil; • Long-term monitoring program for surface water, groundwater, and residential

wells to verify that contaminants are not migrating from the site, installation of additional monitoring wells (if necessary), and hydrogeological testing to ensure that the remedy is protective of human health and the environment.

The natural attenuation of the groundwater contamination (e.g., biodegradation, dilution, dispersion) was expected to reduce the levels of contaminants in the groundwater to acceptable levels over time (approximately 30 years). Until that time, institutional controls would be used to prevent the use of contaminated groundwater.

Remedial Action Implementation

During the remedial design (RD), the selected remedy was divided into two OUs: Drum Excavation (OU1) and Soil Excavation and Treatment (OU2). While there was no active remedy selected for the groundwater, the activities related to the Post-ROD groundwater investigation and monitoring were referred to as OU3.

QUI - Drum Excavation

The remedial action (RA) was initiated by EPA in March 1992 by excavating the buried drums and containers at the site. This action was completed in March 1995. A total of 674 55-gallon drums, 552 5-gallon pails, and 20,353 small "lab-pack" containers were excavated and disposed of off-site. Excavation commenced in Area 4 in September 1992. The quantities of buried materials which were excavated were considerably greater than expected in this area. Area 4 excavation was completed in early March 1993. The drum excavation for Areas 1 and 2 was initiated in March 1994.

At the completion of excavation and removal operations, magnetometer and ground-penetrating radar (GPR) surveys of the areas were performed; this work confirmed that Areas 1, 2, and 4 and the adjacent areas did not contain any remaining metallic objects. Also, the GPR survey results did not indicate any additional areas where soil had been significantly disturbed.

All hazardous waste recovered from the site, including the consolidated lab packs, was disposed of at RCRA-permitted facilities. Disposal operations concluded at the site on March 17, 1995.

The Buried Container Excavation and Disposal remedial action was described in an approved Remedial Action Report dated October 2,1995.

0U2 - Soil Excavation and Treatment

The RD for the soil excavation and treatment portion of the ROD was performed by EPA's ARCS contractor, Camp, Dresser, and McKee (CDM). Through evidence collected during the drum excavation activities, Pitney Bowes was identified as a potentially responsible party (PRP). Subsequently, EPA issued a Unilateral Administrative Order to Pitney Bowes, to conduct the soil remediation. The United States Army Corps of Engineers (US ACE) provided oversight on behalf of EPA. The New York State Department of Environmental Conservation (NYSDEC) also provided oversight of the remedial activities.

Mobilization to the site began in July 1997. The lower field (near Areas 1 and 2) was cleared and compacted to support the low-temperature thermal desorption (LTTD) unit. Soil excavation commenced in August and was completed in November 1997. The initial boundaries of the excavations were located by survey based on the design drawings. A total of 7,300 cubic yards (cy) of soil were excavated during the RA including 1,230 cy from Area 1; 2,672 cy from Area 2; and 3,398 cy from Area 4. Area 3 did not require remediation as it did not have containers or soil contamination that exceeded cleanup levels.

Treated soil was backfilled into the excavation areas after post-excavation sampling results showed that cleanup levels in the excavated areas had been achieved. In order to restore the excavated areas to grade, two additional sources of backfill were required, namely, a local borrow source and off-site fill. The local borrow source was identified and tested for chemical and geotechnical parameters (such as grain size and organic content). The certified-clean off-site fill was purchased from a nearby commercial gravel provider. Approximately 1,100 cy of off-site backfill was placed in the excavations to bring the site back to original condition.

At the completion of treatment operations, the LTTD unit was dismantled and decontaminated. All major components of the LTTD were transported off-site by December 19, 1997. Site restoration began in May 1998 and was completed in July 1998.

The soil excavation and backfill portion of the remedial action was described in an approved Remedial Action Report dated September 1998.

OU3 - Post-ROD Groundwater Investigations

Significant investigations of the site groundwater have been performed since the 1990 ROD to verify that the No Further Action groundwater remedy remained appropriate. The findings of these investigations were summarized in a September 2001 Post-ROD Groundwater Evaluation (PRGE) report. The investigations are discussed in more detail below.

The groundwater investigation began as part of the RD in early 1991. Nine monitoring wells were installed and sampled. Significant levels of VOC contamination were identified migrating from Area 4. Additional wells were installed to characterize the groundwater flowing from Area 4 towards Cleaver Swamp and the water and sediments in Cleaver Swamp. The surface water sampling in Cleaver Swamp verified that significant contamination was not present in the swamp and that the outflow from the swamp was not contaminated. An evaluation of the hydrogeology in this area indicated a very localized area of a downward flow of the groundwater from the overburden into the bedrock aquifer necessitating further investigation of the extent of this contamination.

Five additional deep bedrock monitoring wells and eleven piezometers were installed at the site. Multi-level samplers were installed into the monitoring wells to allow for discrete-zone sampling and hydrogeologic analysis of the local aquifer system. Groundwater was sampled and water levels were recorded on two separate events; one site-wide, comprehensive event and a second event focused on areas of potential concern. A previously unobserved set of water-bearing fractures was discovered at one location. A geophysical analysis was performed to map these fractures so additional monitoring wells could be installed to sample the groundwater migration through the bedrock aquifer in this area. Two additional deep bedrock wells were installed in this area with multi­level samplers. In addition, two short-term pumping tests were performed.

Based on the results of this effort, it was determined that groundwater flow in the overburden generally follows the topography of the site. As a result of this pattern of flow, it is anticipated that any residual VOCs in the overburden would likely be transported towards Cleaver Swamp. The analysis of the monitoring well data suggests that the remaining site-related contamination is migrating into Cleaver Swamp where it is attenuated by natural processes (which include biodegradation, dispersion, and volatilization), and ultimately poses no significant health-related exposure to the public or the environment.

Numerous monitoring wells which were installed to characterize and delineate the groundwater flow at the' site continually showed no contamination. After sampling these wells for over 5 years, EPA determined that these wells no longer needed to be sampled. As a "housekeeping" measure, EPA asked the PRP to abandon 11 monitoring wells, 5 multi-level monitoring wells and 7 piezometers in accordance to NYSDEC protocol. This abandonment effort was completed in 2008 (see figure 2).

V. Progress Since the Last Review

The last five-year review was completed in 2011 and concluded that:

"The implemented remedies at the Sarney Farm Superfund site currently protect human health and the environment in the short term by controlling exposure pathways that could result in unacceptable risks. The levels of contaminants remaining in the soils are

protective of the environment and human health. Institutional controls prohibiting the installation of on-site groundwater wells prevent the ingestion of contaminated groundwater. Groundwater data indicate that contaminant levels are no longer declining as expected; therefore, the remedial action objective of restoring the groundwater to drinking water standards may not be met within a reasonable timeframe. In order for the remedy to be protective in the long term, additional investigation or remedial measures may need to be taken to address the remaining contamination in the groundwater or the RAOs may need to be modified.

The following issue was identified:

"It appears that a source of contamination remains beneath the site. Consequently, EPA is reevaluating the selected remedy to determine if modifications are necessary. Future sampling efforts will be modified to obtain the information necessary to make the decision.

Data collected since the last five-year review continue to indicate that contaminant levels in the groundwater are declining more slowly than anticipated in the ROD. A preliminary evaluation of additional treatment technologies did not indicate that alternative existing technologies would expedite the trajectory for restoration of the ground water. EPA has directed the PRP to modify the future sampling events beginning in 2017 to gather additional sampling information to better evaluate the effectiveness of the remedy.

VI Five-Year Review Process

Administrative Components

The five-year review team consisted of: Urszula Filipowicz, Risk Assessor, Kevin Willis, Remedial Project Manager, and Katherine Mishkin, Site Geologist.

Community Notification and Involvement

On November 19, 2015, EPA Region 2 posted a notice on its website indicating that it would be reviewing site cleanups and remedies at 32 Superfund sites and four federal facilities in New York and New Jersey, including the Sarney Farm. The announcement can be found at the following web address:

http ://www2 .epa. go v/sites/production/files/2015-11/documents/fV 16 fvr public website summary.pdf.

Document Review

The relevant documents and reports which were reviewed in the process of completing this five-year review are included in Table 3.

Data Review

The main area of contaminated groundwater is located between Area 4 and Cleaver Swamp and is approximately one acre in size (see figure 2). In the 2001 Post-ROD Groundwater Evaluation Report, the observed overburden monitoring well water elevations suggested flow was moving toward the swamp area. The general bedrock flow is to the west and southwest and strongly influenced by topographic effects and the patterns of the most transmissive fractures.

Overburden monitoring wells have not been included in a groundwater sampling event since 2007 when they were removed from the site as a housekeeping measure; as noted above concentrations of contaminants of concern in these wells were all below cleanup goals. Currently, groundwater sampling is conducted on an annual basis in the 3rd quarter of each year. The well network consists of bedrock multi-level monitoring wells: MW-7D (shallow and deep), MW-9D (shallow, intermediate, deep), and MW-10D (shallow, intermediate, deep), and five private residential water supply wells ranging from 10.5 to 325 ft bgs.

In general, the groundwater contaminant observed most frequently and at the highest concentrations has been 1,2-dichloroethane (1,2-DCA). The only other VOCs that have been detected during this five-year review period have been acetone, trichloroethene (TCE), and cis-l,2-dichloroethene (cis-l,2-DCE). Acetone and cis-l,2-DCE were both found at concentrations below their criteria (50 ug/L and 7 ug/L, respectively) and TCE (standard of 5 ug/L) was detected once over the review period in MW-9D3 at 5.3 ug/L (see figures 3-5).

The wells located immediately west of Area 4 (MW-7D, MW-9D) have shown slightly declining 1,2-DCA concentrations from 2005 through 2014. In the shallow zone at MW-7D (39 - 70 ft), 1,2-DCA concentrations have fluctuated between 44 and 130 ug/L in this five-year review period. The 1,2-DCA concentrations in the deep zone (72 - 101 ft) have fluctuated during this review period, ranging from 48 ug/L to 130 ug/L. Concentrations of 1,2-DCA in the ports of MW-9D in the shallow zone (38 - 55 ft), intermediate zone (55 — 102 ft), and deep zone (102 — 147 ft) have stable concentrations; during this review period, concentrations ranged from 96-120 ug/L in the shallow zone, 71-120 ug/L in the intermediate zone, and 71-90 ug/L in the deep zone.

Multiport monitoring well MW-10D is geographically located between MW-9D and 199 Benson Hill Road and is underlying the area of secondary contamination, south of Cleaver Swamp. Concentrations of contaminants during this review period are relatively stable with concentrations in the shallow zone (40 - 68 ft) below the MCL of 5 ug/L, concentrations ranging in the intermediate zone (68 - 110 ft) from 8.3 - 48 ug/L, and concentrations ranging in the deep zone (110-144 ft) from 27-41 ug/L.

AMEC consultants have been conducting residential well sampling at homes nearby that are side and downgradient of the site in order to ensure that local residents are not being adversely impacted by migrating groundwater contamination. These residences are

situated within one-half mile of the site along Benson Hill Road (see figure 1). The residential sampling has not indicated any site-related contaminants in excess of State or Federal guidelines in any residential well over this review period. Since there have been no historic detections in the residential wells, it is indicative that these wells are not in hydraulic connection with contaminated fractures in the bedrock.

An annual sampling plan has been enacted throughout the past five years. Ten monitoring points at three locations on-site and four residential wells are sampled at low water table periods to assure that the groundwater contamination at the site followed the expected trends. EPA has directed the PRP to expand the monitoring program for the next FYR.

In summary, the concentrations of 1,2-DCA in the bedrock are asymptotic. Since the overall decreasing trend in 1,2-DC A concentrations is slight, the timeframe for groundwater contamination at the site to reach remediation goals is uncertain.

Site Inspection

A site inspection was conducted on August 11, 2015 by Kevin Willis. During the site inspection, no problems or issues with the ongoing remedial activities were noted.

o The backfilled excavations have not subsided; ® Monitoring wells are functional and securely locked; o Wetlands and upland forested areas have sustained unstressed plant life.

Interviews

EPA interviewed Laura Sarney, daughter of the property owner, to discuss any concerns regarding the site or this five-year review report. No concerns were raised which require further action.

Institutional Controls Verification and Effectiveness

The 1990 ROD indicated that administrative controls may be needed to restrict groundwater use. There is currently a deed notice on a portion of the site indicating that this property is a Superfund site. In addition, EPA believes that the DCDH requirement for installation of new wells currently provides adequate control to ensure that this localized portion of the aquifer is not utilized for drinking water. The DCDH requires that a plan (including the specific location) for drilling a well be submitted for review and approval prior to the well installation. DCDH reviews this drilling plan against the NYSDEC list of inactive hazardous waste disposal sites to determine if there may be any groundwater quality concerns in the vicinity prior to issuing a permit for well installation.

VII. Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

The selected remedy for contaminated groundwater was no further action with natural attenuation of VOCs.

The VOC of concern at the site is 1,2-DCA. Groundwater concentrations of 1,2-DCA found in the bedrock multi-level wells have decreased since the soil remediation, however, results from this five-year review period indicate that concentrations are not decreasing as quickly as expected suggesting that a residual source is present in the bedrock, that restoration of the aquifer within the timeframes envisioned in the ROD may not be possible under the framework of the existing remedy, i.e., that the remedy is not functioning as intended.

Although VOC contamination, and more specifically 1,2-DCA, continue to be detected in onsite bedrock monitoring wells, data collected from the five nearby residential wells (also in bedrock) do not show any detections of 1,2-DCA above the method reporting limit of 1 ug/1. To ensure residents in the vicinity of the site are not exposed to onsite contamination, continual monitoring of the potable wells will continue.

Institutional controls are in place that prevent groundwater use on the site. As stated above, although residences in the area of the site use groundwater for drinking water purposes, routine sampling is conducted and to date, the site has not impacted these wells.

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives (RAO) used at the time of the remedy selection still valid?

There have been no physical changes to the site that would adversely affect the protectiveness of the remedy. Land use assumptions, exposure assumptions and pathways, and cleanup levels considered in the decision document followed the Risk Assessment Guidance for Superfund used by the Agency and remain valid. Although specific parameters may have changed since the time the human health risk assessment was completed, the process that was used remains valid.

The ecological risk assessment that was performed during the post-ROD groundwater investigation continues to be valid. It would be appropriate to resample Cleaver Swamp water arid sediments to assure there are no unexpected changes.

The potential for vapor intrusion into indoor air was not evaluated at the time of the ROD, however it was assessed during the previous five-year review and deemed not to be a concern. As part of this year's review, the maximum concentrations of 1,2-DCA of 130 ppb was compared to the current chemical-specific groundwater vapor intrusion screening levels (VISLs) for 1,2-DCA. These screening values reflects groundwater

levels associated with an indoor air concentration that represents a cancer risk ranging from 1 x 10-4 and lx 10-6 or a non-cancer hazard quotient of 1. The maximum concentration of 1,2-DCA detected in monitoring wells did not exceed the non-carcinogenic VISL and fell within an acceptable risk range for the cancer endpoint. Furthermore, there are no buildings overlying the affected plume area at this time, therefore the vapor intrusion pathway remains incomplete.

The remedial action objectives identified in the ROD are to reduce the concentrations of contaminant in the soils to levels which are protective of human health and the environment and to prevent current and future exposure to the contaminated groundwater. These objectives are still appropriate. At the time the ROD was written, it was expected that excavating the buried containers and cleaning the contaminated soils would remove the sources of contamination and that contamination in the groundwater would reduce to levels below MCLs in approximately a thirty year timeframe. The drum and soil removal reduced concentrations of contaminants in soils to levels which are protective of human health and the environment. Once the buried containers and contaminated soils were remediated, the concentrations of contamination in the groundwater dropped significantly, but subsequent declines in concentration were not as significant as expected... Although there is an overall trend of lower concentrations, EPA does not expect the contaminant levels to diminish to levels below MCLs within the originally approximated thirty year time frame (following the completion of the drum and soil remediation).

A preliminary evaluation of additional treatment technologies during the review period did not indicate that alternative existing technologies would expedite the trajectory for restoration of the ground water. EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater; if it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy ?

No.

Technical Assessment Summary

The generally stable concentrations of 1,2 - DC A during the past five years indicate that a limited source of contamination exists in the bedrock. EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater; if it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site.

VIII. Issues, Recommendations and Follow-up Actions OU(s): 1 Issue Category: Remedy Performance

Issue: Contaminant levels in groundwater are declining more slowly than expected.

Recommendation: (1) EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater; if it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site. (2) Implement the additional sampling that EPA has directed the PRP to perform, which includes: additional sampling of Cleaver Swamp surface water and sediment, sampling for MNA parameters and additional sampling for 1,4-dioxane.

Affect Current Protectiveness

Affect Future Protectiveness

Party Responsible

Oversight Party

Milestone Date

No Yes PRP EPA 11/11/2018

In addition, the following are recommendations related to O&M that do not affect current protectiveness and were identified during the five-year review:

• Future residential well sampling events should use reporting limits that meet the current New York State Drinking Water standard of 0.6 ug/L for 1,2-DCA.

IX. Protectiveness Statement

oui

The implemented remedies at the Sarney Farm Superfund site currently protect human health and the environment in the short term by controlling exposure pathways that could result in unacceptable risks. In order to ensure that the remedy will be protective in the long term, prior to the completion of the fourth five-year review, EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater; if it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site.

Sitewide

The implemented remedies at the Sarney Farm Superfund site currently protect human health and the environment in the short term by controlling exposure pathways that could result in unacceptable risks. In order to ensure that the remedy will be protective in the long term, prior to the completion of the fourth five-year review, EPA will further evaluate existing and emerging technologies to determine if any can be pragmatically used to expedite the restoration of the groundwater; if it is determined that no such technologies are available to restore groundwater within a reasonable timeframe, a determination will be made as to whether a Technical Impracticability waiver is appropriate for a portion of the site..

X. Next Review

The next five-year review report for the Sarney Farm Superfund site is required within five years from the completion date of this review.

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3 TW-10 - TAMS Deep Monitonng Weil (1991) © MW-7S - CDM Monitoring Well (1997) 3 TW-1U - TAMS nTermediate Oejxn Monitonng Well (1991) -^ pz^ _ COM Shaltow Piezometer (1997) 3 TW-1S • TAMS Shallow Monitonng Well (1991) » ft MW3 - COM Monitonng Well (1984) V UW-11D- ESE Multi-Level BedrookWeil

®EV1ID- EBASCO Deep Monitonng Well (19B9) £ MVIA7D - Exieting Bedrock Well Modification ® EW-SS - EBASCO Shallow Monitonng Woll (1989) * P7-16 - ESE Shalow Piezometer

a i3t ac ® SD-8- ESE Sediment Sampling Location (1999) • Well/Piezometer Removed (2011)

Figure 2 Site Plan

Post-Rod Groundwater Evaluation Sarney Farm Supertund Site

Amenia, New York

Prepared by 8JR | Checked by CTM | ^MACTECHs I ROMJ. §.ie«l"*U'J"H notan

Figure 3 1.2-OCA Concentrations in

Groundwater, Aug 2007 to Aug 2015 MW-7 Series

Samey Farm Superfund Site Amenia, New York

nate Created by; MSC 11/0/15 Checked by; AGH 12/08/15

Figure 4 1.2-DCA Concentrations in

Groundwater MW-7 Series

Samey Farm Superfund Site Amenia. New Yortc

1000

900

800

700

_ 600

I < 500

S - 400

300

200

100

%\ \ \ \ \ \ \ \ \, \, \0 \, \r

Figure 5 1,2-DC A Concentrations in

Groundwater Aug 2007 to Aug 2015 MW-9 Series

Samey Farm Superfund Site Amenia, New Yor*

Aug-06 Aug-07 Aug-08 Aug-09 Aug-10 Aug-12 Aug-13 Aug-14 Aug-15 Created by: MSC 11/0/15 Checked by AGH 12/08/15

Tables:

Table 1: Chronology of Site Events

Event Date

Initial discovery of problem or contamination 1980

NPL listing June 10, 1986

Removal actions September 1987

Remedial Investigation/Feasibility Study completed September 27, 1990

ROD signature September 27, 1990

Superfund State Contract September 24, 1991

Administrative Order on Consent With Sarney Trust May 13, 1992

Unilateral Administrative Order issued September 27, 1996

Remedial Action started March 30,1992

Construction started November 30, 1992

Construction completed September 29, 1998

First Five-year Review September 21, 2006

Second Five-year Review July 1.2011

Tables:

Table 1: Chronology of Site Events

Event Date

Initial discovery of problem or contamination 1980

NPL listing June 10, 1986

Removal actions September 1987

Remedial Investigation/Feasibility Study completed September 27, 1990

ROD signature September 27, 1990

Superfund State Contract September 24, 1991

Administrative Order on Consent With Sarney Trust May 13, 1992

Unilateral Administrative Order issued September 27, 1996

Remedial Action started March 30, 1992

Construction started November 30, 1992

Construction completed September 29, 1998

First Five-year Review September 21, 2006

Second Five-year Review July 1.2011

Table 2: Annual System Operations/O&M Costs

Cost per Year Groundwater Monitoring, Sampling, and Analysis $20,000 Data Management and Reporting $30,000 Total Estimated Cost $50,000

Table 3: Documents, Data, and Information Reviewed in Completing the Five-Year Review

Document Title, Author Submittal Date

Remedial Investigation/Feasibility Study, Ebasco, Inc. 1987

Record of Decision, EPA 1990

Final Remedial Design Report, USACE 1998

Post-ROD Groundwater Evaluation, QST 2001

Remedial Action Report, EPA 2001

Preliminary Close-Out Report, EPA 2002

Annual Groundwater Sampling Reports, MACTEC/AMEC 2001-2015

Five-year Groundwater Evaluation Report, MACTEC/AMEC 2006

EPA guidance for conducting five-year reviews and other guidance and regulations to determine if any new Applicable or Relevant and Appropriate Requirements relating to the protectiveness of the remedy have been developed since EPA issued the ROD.