Five-Year Review ReportHertel Landfill Superfund Site

Town of PlattekillUlster County, New York

Prepared by:

United States Environmental Protection AgencyRegion 2

New York, New York

September 2015

~ ~;( 3; )o~&-~~-------~------------------Walter E. Mugdan, Division DirectorEmergency and Remedial Response DivisionU.S. Environmental Protection Agency

Date

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Table of Contents Executive Summary ............................................................................................................ i Five-Year Review Summary Form ..................................................................................... ii I. Introduction ............................................................................................................ 1 II. Site Chronology ...................................................................................................... 1 III. Background ............................................................................................................ 1 Site Location .........................................................................................................1 Physical Characteristics ................................................................................ 1 Geology/Hydrogeology ................................................................................. 2 Land and Resource Use ................................................................................. 2 History of Contamination .............................................................................. 2 Initial Response ............................................................................................ 2 Basis for Taking Action ................................................................................ 3 IV. Remedial Actions .................................................................................................... 3 Remedy Selection ........................................................................................ 3 Remedy Implementation ............................................................................... 4 Institutional Controls and Implementation ....................................................... 5 System Operations, Maintenance and Monitoring ............................................ 6 V. Progress Since Last Five-Year Review ...................................................................... 7 VI. Five-Year Review Process ....................................................................................... 8 Administrative Components .......................................................................... 8 Community Involvement ............................................................................... 8 Document Review ........................................................................................ 8 Data Review... ............................................................................................. 8 Site Inspection .......................................................................................... 12 Interview…… .......................................................................................... 13 Institutional Controls Verification and Effectiveness ..................................... 13

Table of Contents Continued VII. Technical Assessment ............................................................................................ 13

Question A: Is the remedy functioning as intended by the decision documents? ..................................................... 13

Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives used at the time of the remedy still valid? ........................... 14

Question C: Has any other information come to light that could call into question the protectiveness of the remedy? .................. 15

Technical Assessment Summary ............................................ 15 VIII. Issues/Recommendations, and Follow-up Actions ..................................................... 16 IX. Protectiveness Statement ......................................................................................... 16 X. Next Review .......................................................................................................... 16

TABLES Table 1: Chronology of Site Events Table 2: Documents, Data, and Information Reviewed in Completing the Five-Year Review

FIGURES Figure 1: Hertel Superfund Site Location Map Figure 2: Hertel Landfill Superfund Site Monitoring Well and Sediment and Surface Water Sampling Locations Map Figure 3 Hertel Landfill Site (Landfill Portion) and Private Well Locations Map Figure 4: Groundwater Flow Model Well Exclusion Buffer

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EXECUTIVE SUMMARY EPA has completed the fourth five-year review for the Hertel Landfill Superfund site, located in the Town of Plattekill, Ulster County, New York. The triggering action for this statutory review is the signature date of the previous five-year review, April 2010. Based upon a review of the Record of Decision, Record of Decision Amendment, Remedial Action Reports, maintenance reports, monitoring reports, and an inspection of the Site, it has been concluded that the remedy is protective of human health and the environment.

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Five-Year Review Summary Form

Issues/Recommendations 

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

OU 1 ‐ No issues 

SITE IDENTIFICATION

Site Name: Hertel Landfill Site

EPA ID: NYD0980780779

Region: 2 State: NY City/County: Town of Plattekill/Ulster County

SITE STATUS

NPL Status: Final

Multiple OUs? No

Has the site achieved construction completion? Yes

REVIEW STATUS

Lead agency: EPA [If “Other Federal Agency”, enter Agency name]: Click here to enter text.

Author name (Federal or State Project Manager): Lorenzo Thantu

Author affiliation: EPA

Review period: 4/2010 to 3/2015

Date of site inspection: 9/15/2014

Type of review: Statutory

Review number: 4

Triggering action date: 4/13/2010

Due date (five years after triggering action date): 4/13/2015

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Five-Year Review Summary Form (Continued)

Issues and Recommendations Identified in the Five‐Year Review: 

OU(s): Click here to enter text. 

Issue Category: Choose an item. 

Issue: Click here to enter text. 

Recommendation: Click here to enter text. 

Affect Current Protectiveness 

Affect Future Protectiveness 

Party Responsible 

Oversight Party  Milestone Date 

Choose an item.  Choose an item.  Choose an item.  Choose an item.  Click here to enter a date. 

Protectiveness Statement(s) 

Operable Unit: OU1 

Protectiveness Determination: Protective 

 

Protectiveness Statement: The  remedy  for  the Hertel  Landfill  Superfund  site  is  protective  of  human  health  and  the environment.   

Sitewide Protectiveness Statement 

Protectiveness Determination: Protective 

 

Protectiveness Statement: The  remedy  for  the Hertel  Landfill  Superfund  site  is  protective  of  human  health  and  the environment.   

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I. Introduction The purpose of a five-year review is to evaluate the implementation and performance of a remedy in order to determine if the remedy is and will continue to be protective of human health and the environment and is functioning as intended by the decision documents. The methods, findings, and conclusions of reviews are documented in the five-year review. In addition, five-year review reports identify issues found during the review, if any, and document recommendations to address them. This is the fourth five-year review for the Hertel Landfill Superfund site (Site), located in the Town of Plattekill, Ulster County, New York. This five-year review was conducted by the Environmental Protection Agency (EPA) Remedial Project Manager (RPM) Lorenzo Thantu. The 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). This report will become part of the Site file. The triggering action for this statutory review is the signature date of the previous five-year review, April 2010. A five-year review is required at this Site because the remedial actions selected at the Site will leave hazardous substances, pollutants, or contaminants on Site above levels that allow for unlimited use and unrestricted exposure. The Site is being addressed in one operable unit (OU). This OU is the subject of this five-year review. II. Site Chronology Table 1 (attached) summarizes the Site-related events from discovery to the present.

III. Background

Site Location

The Hertel Landfill Superfund site is located in the Town of Plattekill, Ulster County, New York, just south of U.S. Route 44/NY Route 55 and approximately midway between Bedell Avenue and Tuckers Corner Road (Figure 1).

Physical Characteristics Wetlands border the Site property to the north, south, and east, and a small unnamed stream crosses the southern and eastern portion of the Site and flows adjacent to the landfill. The unnamed stream flows into Pancake Hollow Creek and then Black Creek and then the Hudson River. An approximate 15-acre portion of the 80-acre Site property was a waste disposal area that was established in 1963 as a private landfill accepting municipal and industrial waste.

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A locked gate has been installed across the unpaved main access road near Route 44/55 and a six-foot high chain-link perimeter fence has been erected around the northern, western, southern, and southeastern boundaries of the landfill area. The gate and fence act to prevent unauthorized personnel from entering the Site. Geology/Hydrogeology There are two aquifers beneath the Site. The bedrock material is the Austin Glen formation and described as a greywacke and shale; variegated light blue to blue-grey fine- to medium-grained sandstone (greywacke) with occasional seams of shale having been observed. The rock has well-defined bedding planes and the upper few feet are slightly weathered. The overburden is a glacial till deposit consisting of a mixture of material (clay, silt, sand, gravel, and boulders) which widely range in size, shape, and permeability. Overlying the till deposit is a layer of light brown fine sand and silt. Land and Resource Use The Site and the area surrounding the Site are zoned residential. Approximately 1,350 people live within three miles of the landfill. There are about 500 people living within a mile of the Site. Residents within the area obtain their drinking water from individual drinking water wells. No permanent structures are located on the Site. History of Contamination The Hertel Landfill was established in 1963 as a private landfill accepting municipal and industrial waste. Approximately 15 acres of the Site property were used for disposal. In 1976, the Ulster County Department of Health (UCDOH) revoked the landfill permit for a variety of violations, among which were allegations of illegal industrial dumping. This UCDOH action and a Town of Plattekill ordinance prohibiting the dumping of out-of-town garbage resulted in the permanent closing of the Hertel Landfill in March 1977. Initial Response Sampling and analysis of Site groundwater in 1980 and 1982 revealed measurable amounts of several metals. Three leachate samples were collected in March and May 1981 by the New York State Department of Environmental Conservation (NYSDEC). Analyses of these samples detected phenols, organic compounds, and a number of metals. Based on these results, NYSDEC placed the Hertel Landfill site on the New York State Registry of Inactive Hazardous Waste Disposal Sites. In 1983, the Site was recommended for inclusion on the National Priorities List (NPL) by NYSDEC and in October 1984, the EPA proposed the Hertel Landfill site for inclusion on the NPL. In June 1986, the Site was placed on the NPL.

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Basis for Taking Action During the initial Remedial Investigation/Feasibility Study (RI/FS), a risk assessment was performed. Under possible future land-use conditions, adults exposed to contamination from residing on Site presented an unacceptable cancer risk. In addition, current/recreational use of the Site presented an unacceptable cancer risk. An environmental assessment was also conducted. It was determined that a general trend of elevated concentrations of organic and inorganic contaminants exists in one or more environmental media at the Site and present potential ecological effects. In 2003, an updated baseline human health risk assessment was performed to evaluate potential risks from exposure to the contaminated groundwater at the landfill and downgradient. In addition, the Baseline Ecological Risk Assessment (August 2004) evaluated the extent to which current conditions posed a risk to ecological receptors at the Site, including any risk associated with residual sediment contamination and provided information necessary for evaluating and addressing groundwater impacts at the Site. Ecological receptors of concern include sediment-dwelling (benthic) intervertebrates, zooplankton, amphibians, and aquatic-feeding insectivorous birds based on exposure potential and sensitivity. Based upon the results of this reassessment and the risk assessment, Site-related human and ecological exposures were found to be at acceptable levels. IV. Remedial Actions Remedy Selection

A Record of Decision (ROD) for the Site was signed in 1991. The remedy selected in the 1991 ROD included:

Construction of a multi-layer cap consistent with New York State Part 360 solid waste landfill closure requirements;

Additional soil sampling along the western portion of the disposal area; Regrading and compaction of landfill mound to provide a stable foundation for the

placement of the cap prior to its construction; Construction of a gas venting system; Performance of air monitoring prior to, during, and following construction at the Site, to

ensure that air emissions resulting from the cap construction meet applicable or relevant and appropriate requirement (ARARs);

Quarterly groundwater monitoring program using existing groundwater monitoring wells, and six additional wells to be installed beyond the capped area. The monitoring program will include sampling of selected residential wells with subsequent follow-up actions as necessary;

Construction of fencing around the perimeter of the capped area;

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Ordinances be established or restrictions imposed on the deed to ensure that future use of the Site property will maintain the integrity of the cap;

Installation of a groundwater extraction and treatment system to control leachate migration; Delineation and evaluation of the wetlands and the drainage channels flowing through

these wetlands adjacent to the landfill; Full evaluation of the wetlands prior to remediation activities to determine any measures

which may be necessary to mitigate potential negative impacts to the wetlands; Performance of a treatability study to demonstrate the effectiveness of the innovative

technology for groundwater treatment; Disposition of treatment residuals in accordance with Resource Conservation and

Recovery Act requirements, including its Land Disposal Restrictions; and Implementation of Alternative 4 as a contingency remedy should the treatability study

indicate the innovative groundwater treatment technology is not effective.

Given the improvements in Site groundwater quality over the ensuing several years, EPA re-evaluated the active groundwater extraction and treatment remedy specified in the 1991 ROD. Based on this evaluation, in 2005, EPA approved a ROD Amendment for the Site. The ROD clarified the remedial action objectives (RAOs) for the Site. They are:

(1) protect human health by ensuring that future residents are not exposed to contaminated groundwater; and

(2) reduce the further contamination of the wetlands in the area, and the migration of contaminants in groundwater.

The major components of the modification to the selected remedy include:

Elimination of the groundwater extraction and treatment system portion of the 1991 selected remedy;

Implementation of a long-term monitoring program where groundwater, surface water, sediment samples, and residential well water will be collected and analyzed on an annual basis to ensure that the remedy remains protective of human health and the environment (Figures 2 and 3); and

Maintenance of Site access restrictions, and implementation of institutional controls to prohibit any use of the Site that would impair the effectiveness of the landfill cap and leachate collection system and to prohibit any digging of wells or extraction of groundwater in or immediately adjacent to the landfill cap.

Remedy Implementation In September 1992, EPA issued a Unilateral Administrative Order (UAO) to six Potentially Responsible Parties (PRPs), directing them to perform the remedial design/remedial action (RD/RA). Ford Motor Company (Ford) was the only PRP at the time to comply with the UAO. In 1994, Ford completed a pre-design investigation for the Site which defined the extent of the landfill

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mass, modeled Site groundwater dynamics and characterized soil, groundwater, surface water, and sediment contamination. The groundwater modeling predicted that a groundwater pump and treat system, if implemented, would have a negative impact on the wetlands immediately adjacent to the landfill, without achieving the goal of remediating groundwater contamination in the saturated zone. In addition, Ford installed gas probes to monitor potential landfill gases generated by the decomposition of landfill material and, in 1995, installed a locked chain link fence to prevent unauthorized access to the landfill. The remedial pre-design investigation, which formed the basis of the design of the landfill cap, was approved by EPA in September 1996. Thereafter, initial work for the construction of the cap began with the removal of vegetation growing over the landfill area, as well as the implementation of erosion control measures. In February 1997, EPA issued a second UAO to eight additional PRPs, directing these parties to cooperate and participate in the Site cleanup with Ford and with Golden Books Publishing Co., Inc. (formerly Western Publishing Co., Inc.), which had come into compliance with the first UAO. In September 1998, EPA entered into a Consent Decree settlement ("RD/RA Consent Decree") with 11 PRPs, all of which had been recipients of one of the two previously issued UAOs, for continued performance of the RD/RA and recovery of EPA's and NYSDEC's Site costs. At the same time, EPA entered into a second Consent Decree settlement with eight other PRPs to recover Site costs. EPA entered into two additional cost recovery Consent Decree settlements with a total of five other PRPs, including F.I.C.A., a partnership that was the successor to Dutchess Sanitation Services, Inc. The multi-layer cap was constructed over the landfill portion of the Site in 1998. The cap is a multi-layered design that complies with title 6 NYCRR Part 360 and covers approximately 13 acres of the landfill. In addition to the cap, a fence has been installed at the Site. The gas venting system and leachate collection system were constructed and are operational. The gas venting system and leachate collection system are maintained and monitored by the Site contractor. Institutional Controls Implementation The 2005 ROD Amendment specified that institutional controls would be put in place to prohibit any use of the Site that would impair the effectiveness of the landfill cap and leachate collection system, and to prohibit any digging of wells or extraction of groundwater in or immediately adjacent to the landfill cap. Institutional controls would also be put in place to insure continued access to the Site by EPA and the State of New York. Appropriate institutional controls have been put in place at the Site. The Town of Plattekill Code, Chapter 110-53 (Aquifer Protection Zone) was enacted into law solely for the Hertel Landfill site. It establishes a designated Environmental Impact Assessment Area (EIAA) II (Figure 4). Properties within EIAA II are subject to multiple water supply development requirements, which include Site-specific drilling, testing, and water quality studies. These studies are required to be completed by a qualified hydrogeologist or engineer representing the applicant. The application may also be referred to an independent hydrogeologist or engineer selected by the Town at the

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applicant's expense. EPA has worked with the PRPs to develop and implement deed restrictions on several properties. On November 26, 2013, the PRPs submitted a letter to EPA documenting that all institutional controls as required by the 2005 ROD Amendment have been met. The November 26, 2013, letter states that the institutional controls in the form of deed restrictions have been implemented/recorded for all parcels except parcel 4-14.000. The owner of this parcel is deceased and the representative for the estate of the parcel owner did not agree to a deed restriction. However, upon further review, it has been determined that the deed restriction for parcel 4-14.000 is no longer required. Based on groundwater flow model conducted by the PRPs, additional pumping from a hypothetical potable drinking water well on the affected 1.1+/- acre portion of 5+/- acre parcel 4-14.000 had been addressed and fully accounted for in the well-exclusion zone buffer (Figure 4). Specifically, the 1.1+/- acre portion of parcel 4-14.000 was included in the well-exclusion zone as a result of the combined effect of possible future groundwater diversions from potable water wells already located within parcels 4-11.011 and 4-13.001. (Parcels 4-14.000, 4-11.011 and 4-13.001 are synonymous with parcels #14, #11.001 and #13.001, respectively in Figure 4. In addition, all three parcels are included within the EIAA II.) Therefore, since deed restrictions on Parcels 4-11.011 and 4-13.001 have already been acquired and recorded, there would be no potential concern for future groundwater diversions from additional potable water wells and, therefore, additional restriction for parcel 4-14.000 would no longer be required. As discussed above, the Town Code, Chapter 110-53, and the groundwater flow model conducted have addressed the 2005 ROD Amendment’s institutional controls requirement. It needs to be also noted that of the 5+/- acre parcel 4-14.000, over which the original plan was to acquire a 1.1+/- acre permanent subsurface easement, the groundwater flow model’s well exclusion buffer shows that the portion of the property over which a deed restriction originally would be placed consists mostly of wetlands and also the 100-foot wetland development buffer which would be required by NYSDEC for any development/construction activities conducted in or near wetlands areas. It is highly unlikely that the State of New York, County of Ulster, or Town of Plattekill would allow the development of a potable water well within the wetlands or their corresponding development buffer; therefore, in practical terms, the area affected by the deed restriction amounts to less than 840 square feet (less than 0.02 acres).

System Operations, Maintenance and Monitoring The landfill cap and leachate collection system are being monitored and maintained by the PRPs as set forth in the Remedial Design/Remedial Action Consent Decree and the EPA-approved Operation and Maintenance Manual. In accordance with the EPA-approved monitoring plan for the Site, post-closure monitoring is currently occurring on a biannual basis, and post-closure maintenance is being implemented and reported on a quarterly basis to EPA. The current groundwater monitoring program includes sampling of approximately 21 groundwater monitoring wells located at the Site and analyzed for organic and inorganic compounds, as well as 11 residential/potable wells located downgradient of the Site. Monitoring wells are sampled semi-annually for organic and inorganic compounds and residential wells are sampled annually. The

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current surface water and sediment monitoring program consists of the annual collection of seven sediment and surface water samples. The gas venting systems appear to function as designed. Monitoring reports indicate that measurements taken at vents do not exceed air quality standards. The cover system and slopes appear to be well maintained. Potential Site impacts from climate change have been assessed, and the performance of the remedy is currently not at risk due to the expected effects of climate change in the region and near the Site. V. Progress since Last Five-Year Review The previous five-year review, completed in April 2010, concluded: The remedy for the Hertel Landfill Superfund site protects human health and the environment in the short-term. Currently, there are no exposure pathways that could result in unacceptable risks and none are expected as long as the engineered, access and institutional controls selected in the decision documents continue to be properly monitored and maintained. The 2010 five-year review made several recommendations:

Increase the number of wells in the upgradient well network in order to more robustly characterize the background conditions, primarily iron and manganese concentrations.

Perform an assessment of iron and manganese conditions in the background and downgradient wells to more fully assess whether contaminants in downgradient monitoring and residential wells are Site related or representative of naturally occurring conditions.

Evaluate the performance of the gas venting system and the leachate collection system to determine if optimization is necessary.

Evaluation of 2010-2014 groundwater-quality data collected from monitoring wells that circumscribe the cap area, sentinel wells located to the northwest of the landfill near the wetland, and residential wells, show elevated levels of iron, manganese, sodium; arsenic, antimony and thallium are sporadically present at levels slightly in excess of NYSDEC standards in on-site monitoring wells. Iron, manganese, and sodium exceed secondary standards but do not exceed human health risk-based criteria. Iron and manganese are considered to be naturally occurring in the overburden and shallow bedrock in the Hertel Landfill area. Elevated levels of iron and manganese found to be persistent and localized by the toe of the landfill may be associated with geochemical changes associated with leachate generation. Arsenic, antimony, and thallium exceedances are localized and sporadic. Results of groundwater analysis from residential wells along Route 44/55 indicate that the iron, manganese, sodium, and to a lesser extent, copper have been detected above their respective secondary maximum contaminant levels (MCLs). Consistent with the on-site wells, the maximum detected concentration of iron and manganese did not exceed their respective human health risk-based criteria (the RSL). Copper was detected in one private well sample above NYSDEC standards but was not detected in the on-site monitoring wells above the criteria, suggesting that the exceedances of copper in the private wells are not Site-related and may be related to secondary sources (e.g., copper plumbing or brass water fixtures). Furthermore,

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several geological and groundwater reports published by the U.S. Geological Survey (USGS), U.S. Department of the Interior, and New York Rural Water Association suggest that iron and manganese are both naturally occurring constituents in background levels within the regional geologic formation. These reports, coupled by observation of the iron and manganese concentration trends at the Site, indicate that the Site geology is a natural contributor to elevated levels of iron and manganese historically observed at the Site and regionally. In addition, the performance of the gas venting system and the leachate collection system has been evaluated and details are provided in Section VI of this document. In summary, it was concluded that both systems have been performing and operating as designed and, therefore, optimization is not necessary. VI. Five-Year Review Process Administrative Components The five-year review team consisted of Lorenzo Thantu (Remedial Project Manager), Edward Modica (Hydrogeologist), Mindy Pensak (Ecological Risk Assessor) and Julie McPherson (Human Health Risk Assessor). Community Involvement EPA Community Involvement Coordinator (CIC), Larisa Romanowski, prepared a five-year review public notice for the Hertel Landfill site and posted it on EPA’s Hertel Landfill site web page. The public notice was distributed via email to local Town officials and other interested parties. Copies of the public notice were also sent to interested parties via the U.S. Postal Service. The announcement indicated that EPA is conducting a five-year review of the remedy for the Site to ensure that the implemented remedy remains protective of public health and the environment and is functioning as designed. It also indicated that once the five-year report is completed, the results will be made available in the local Site repository. The notice included the telephone number, email and postal address of the RPM and CIC for questions related to the five-year review process or the Hertel Landfill site. Document Review The documents, data, and information which were reviewed in completing the five-year review are summarized in Table 2 (attached). Data Review The data review covers water- and sediment-quality data derived from sampling events from March 2010 through May of 2014. Since the completion of the landfill cap at the Site, the groundwater, sediment and surface water, residential wells, and landfill gas vents have been monitored and sampled pursuant to the RD/RA Consent Decree operation and maintenance plan.

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Groundwater Monitoring Wells The groundwater monitoring program includes sampling of 21 groundwater monitoring wells located on or adjacent to the site; all wells are sampled on a semi-annual basis for organic and inorganic compounds. In general, the chemical analyses show that iron and manganese are found in most wells at elevated levels above their respective New York Department of Conservation Water Quality Regulations (NYSDEC WQR), which are 300 parts per billion (ppb) for iron, 300 ppb for manganese, and 500 ppb for iron and manganese combined; these are secondary MCLs established for aesthetic purposes and are not health based criteria. To a lesser extent, groundwater monitoring wells also show sporadic exceedances of thallium, antimony, and arsenic. The discussion of inorganic results for wells based on downgradient versus upgradient location are provided in more detail below. Groundwater quality data for the last five years show no exceedances for organic compounds, with the exception of estimated concentrations of benzene reported for well MW-W1SA at 1 ppb. Specifically, at this well MW-W1SA, the concentration was qualified as estimated by the laboratory at 1 ppb. In all other instances, the concentrations of benzene were less than the instrument detection limit of 1 ppb. As the New York State Department of Environmental Conservation Groundwater Quality Standards (NYSDEC GWQS) is set at 1 ppb, exceedance was conservatively assumed. Results from monitoring wells installed along the southwest end of the landfill show detections of iron and manganese, with sporadic detection of thallium and sulfide. In well MW-16DS, concentrations of iron ranged from 1,660 ppb to 32,900 ppb whereas concentrations in manganese ranged from 24 ppb to 305 ppb. There were no detections above the NYSDEC WQRs or MCLs reported for well MW-W3S. The wells are located on the up-gradient side of the landfill and the observed chemistry is likely a reflection of ambient chemical conditions in the aquifer. Results from monitoring wells installed along the eastern edge of the landfill show elevated levels of iron, manganese, sodium, and arsenic; sporadic detection of antimony and thallium in excess of the NYSDEC WQRs or MCLs were also reported. Results from wells down-gradient of the landfill show slight increasing trends for iron, manganese, sodium, and arsenic whereas wells up-gradient of the landfill showed decreasing trends over time. The highest concentrations of iron and manganese for this five-year review period were observed in well MW-W1SA, located down-gradient near the north end of the landfill, where average concentrations were 18,933 ppb and 15,878 ppb respectively. Lower concentrations for these metals were reported in well MW-10D located further south along the landfill, where the average concentrations for iron and manganese were 170 ppb and 147 ppb, respectively. The highest sodium concentrations were reported for well MW-W1D, at an average of 64,678 ppb for the period (compared to NYSDEC WQR standard of 20,000 ppb). Sodium is also observed in wells MW-W1SA and MW-11D, but at less than half the average concentrations found in MW-W1D. Arsenic was observed in wells MW-W1SA, MW-W2SA, and MW-11D, where concentrations ranged from 26 to 57.4 ppb (compared to NYSDEC WQR standard of 25 ppb).

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Analysis of samples from monitoring wells installed along the north edge of the landfill show elevated levels of iron, relatively high levels of manganese, and sporadic detections of sodium, magnesium, thallium, and sulfide. In well MW-14S, the average iron concentration for the period was 2,249 ppb, whereas the average manganese concentration was 13,352 ppb. Similarly, in well MW-14I, the average iron concentration was 1,460 ppb and the average manganese concentration was 14,089 ppb. The relatively high levels of manganese observed in wells located in the area toe-of-slope of the landfill may reflect the enhanced leaching of manganese from soil/rock matrix in the saturated zone within the landfill area. Analysis of samples from sentinel monitoring wells located down-gradient and northeast of the landfill also show elevated levels of iron, manganese, and sodium at levels above groundwater quality standards. In addition, there were sporadic but minor detections of antimony, thallium, and sulfide. These results show no discernable trends over time and are consistent with results from previous monitoring events. For the wells MW-P1, MW-17I, and MW-2D, located adjacent to the access road, the average sodium concentration for the period was 34,509 ppb. Average concentrations of iron and manganese were 11,832 ppb and 4,080 ppb, respectively, for well MW-P1. For wells located northeast of the cap near the wetland (wells designated as MW-K{1,2,3}[S,D]), concentrations of iron and manganese were detected at levels in excess of standards, although at relatively lower levels than wells nearer to the landfill (an average of 6,654 ppb for iron and 723 ppb for manganese). The groundwater quality data collected from the existing background and downgradient monitoring wells, discussed above, indicate that the elevated iron and manganese concentrations in the downgradient monitoring and residential wells are representative of naturally occurring conditions, Potable Wells in Residential Area As part of the Site monitoring program, 11 residential wells along Route 44/55 are sampled, normally on an annual basis, for organics and inorganics. For this 2010-2014 review period, iron, manganese, copper, and sodium were detected above their respective MCLs in several potable wells. For the period September 2010 to October 2013, metal exceedances for three or more consecutive sampling events were reported for wells PW-1, PW-2, and PW-11; in residential well PW-1, concentrations of iron ranged from 303 ppb to 3,780 ppb between 2011 and 2013; in PW-2, concentrations of iron ranged from 444 ppb to 1,280 ppb between 2010 and 2012 whereas concentrations of manganese were reported at 338 ppb and 399 ppb for 2011 and 2012; in PW-11, concentrations of copper ranged from 376 ppb to 913 ppb between 2010 and 2012, whereas concentrations of sodium ranged from 376 ppb to 913 ppb between 2010 and 2013. There were no exceedances reported for wells PW-3 and PW-4 for the period. The maximum detected concentrations of inorganics in the private wells are compared to their respective residential groundwater Regional Screening Levels (RSLs) and MCLs (National Primary Drinking Water Standards) and NYSDEC WQRs. Although the maximum detected

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concentrations of iron and manganese did exceed their respective NYSDEC standards, they did not exceed their respective human health risk-based criteria (RSL). NYSDEC standards are considered secondary MCLs and are based on aesthetic considerations (i.e. smell and taste). Although copper was detected in one private well sample above NYSDEC standards, it was not detected in the on-site monitoring wells above the respective criteria. This suggests that the exceedances of copper in the private wells are not Site-related and may be related to secondary sources (e.g., copper plumbing or brass water fixtures). The private wells will continue to be monitored. Surface Water and Sediment The monitoring program includes annual collection of sediment and surface-water samples from six locations on the eastern edge of the landfill, from the upstream area of the unnamed creek to the toe-slope of the landfill, and from one location near the wetland area northeast of the landfill. Sediment quality data for the years 2010-2014 indicate metal concentrations patterns similar to previous years. Concentrations of manganese in sediment exceeded the NYSDEC Lowest Effects Level (LEL) standard of 460 parts per million (ppm) at all sampling stations (SSW-4, -4A, -lA, -3, -6, -5, and -2) for the past five years. The distribution of manganese concentrations from upstream to downstream is erratic; that is, there is no progressive decrease or systematic pattern of changing concentration with distance downstream. For example, for the 2014 sampling event, the concentrations of manganese in sediments are 1,460 ppm, 1,380 ppm, 3,150 ppm, 2,240 ppm, 537 ppm, and 1,120 ppm from upstream to downstream locations. Other metal contaminants reported in the sediments that exceed LEL standards include arsenic, copper, nickel, lead, silver, zinc, and cadmium. These appear to be erratically distributed among the sampling stations. Exceedances of the pesticide 4,4’-DDT were also reported at location SSW-3 in 2010 and 2011. The current concentrations of manganese and iron are well below sediment concentrations analyzed in the Baseline Ecological Risk Assessment (BERA) completed in 2003. This BERA was performed prior to the ROD Amendment of 2005, and it stated that the concentrations identified during the sampling events performed in 2002 and 2003 did not pose a threat/impact to the wetlands. Surface-water quality data for the years 2010-2014 also showed metal concentrations patterns to be similar to previous years. For arsenic, there were no decreasing or increasing trends noted at any of the sampled locations. A substantial spike was observed at all sample locations with the exception of location SW-2 for arsenic above the NYSDEC ambient water quality criteria (AWQC) standard of 150 ppb during the 2011 sampling event. The average concentration of this spike, likely attributed to groundwater fluctuating levels intercepting localized supplies of metal oxides, was 3,164 ppb; however, the average concentration for other years for all samples during the previous five year period was 6.42 ppb. Although chromium concentrations appear to be gradually increasing at locations SW-1A and SW-3, concentrations do not exceed the NSYDEC AWQC standard. No increasing trends in concentrations of manganese were observed at any sample location. Concentrations of manganese exceeded the NYSDEC AWQC standard of 300 ppb once in 2013 for SW-4 at 485 ppb, but more frequently at locations SW-3, SW-6, SW-5, and

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SW-2. Manganese concentrations ranged from 104 ppb to 2,320 ppb for all locations. Elevated concentrations of iron were also reported at these sampling locations following the manganese pattern of detection but at concentrations two to five times greater. No NSYDEC AWQC standard is available for iron. As with sediments, there was no progressive decrease or increase of concentration with distance downstream. As mentioned above, several geological and groundwater reports published by the USGS, U.S. Department of the Interior, and New York Rural Water Association suggest that iron and manganese are both naturally occurring constituents in background levels within the regional geologic formation. These reports, coupled by observation of the iron and manganese concentration trends at the Site, indicate that the Site geology is a natural contributor to elevated levels of iron and manganese historically observed at the Site and regionally. Air (Gas Vent) Quality All gas vents are field sampled on an annual basis using a four-gas detector. Samples are analyzed for T14 (VOA), carbon dioxide, and methane. No combustible gas levels have been reported in off-site gas probes screened in non-landfill material. No standard exceedances for these compounds have been recorded for the period. Site Inspection A Site inspection was performed on September 15, 2014. The following parties were in attendance: Wayne Mizerak, NYSDEC (Via Conference Call) Tom Morris, IBM Cristian Nieto, Hatch Mott Mcdonald Mindy Pensak, EPA Risk Assessor Vatsal Shah, Hatch Mott Mcdonald Lorenzo Thantu, EPA RPM Mohamed Zakkar, Ford The gas venting system and leachate collection system are maintained and monitored by the Site contractor. During the Site visit, the Site contractor stated that the leachate collection system and gas venting system have had no recovery in the past couple of years. No combustible gas levels have been recorded in the off-site gas probes screened in the non-landfill material, indicating that there is no migration of gas away from the main landfill. This is likely the result of the age of the material in the landfill, which, for the most part, has already generated its peak gas quantity. In addition, the Site is relatively shallow, in terms of typical solid waste landfills, and consequently would not be expected to generate extensive quantities of gas. No standard exceedances for these compounds (i.e., T14 VOA, carbon dioxide, and methane) have been recorded over the evaluation period.

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As for the leachate collection system, the moisture content of the waste has continued to decrease, as a result of cap construction, which was evidenced by the decrease of the leachate volume being generated and discharged into the sump. Immediately after capping, the Site contractor periodically pumped and removed collected leachate from the sump. However, as the cap became effective, the amount of leachate produced was reduced to the point where it has not been necessary to empty the sump. It has been observed that the leachate drain has not collected leachate during the past five years. The fact that the leachate collection system has not collected leachate in the past five years indicates that the landfill cap is performing as designed, and is not allowing rainwater to enter the landfill waste to produce additional leachate. Interview No interviews were conducted as part of this five-year review. Institutional Controls Verification and Effectiveness As noted above, the institutional controls have been fully implemented since the previous April 2010 five-year review. VII. Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents? According to the 1991 ROD, the remedy calls for a multi-layered cap, a drainage system, a gas venting system, leachate collection system, groundwater monitoring program, and access restrictions. The cap complies with title 6 NYCRR Part 360 and covers approximately 13.5 acres. The cover system and slopes appear to be well maintained. No breaches or depressions were noted during Site inspection. Runoff control features appear to be in good repair. The gas venting systems appear to function as designed. Monitoring reports indicate that measurements taken at vents and off-site probes do not exceed air quality standards. A French drain system was also put into place as part of the cap design, the purpose of which is to dissipate excess moisture beneath the cap and relieve hydraulic pressure in the toe of slope area. The drainage system (i.e., leachate collection system) is located on the eastern side-slope of the landfill above the groundwater elevation and consists of a perforated pipe installed in a trench filled with crushed stone. The leachate collection system has not collected any leachate in the past 5 years, which indicates that the drain and cap are functioning as designed. A perimeter fence surrounds the capped area and prevents unauthorized personnel from entering the Site.

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Performance of the remedy is evaluated with groundwater-quality data collected in monitoring wells that circumscribe the cap area, sentinel wells located to the northwest of the landfill near the wetland, and residential wells. Monitoring wells are sampled semi-annually for organic and inorganic compounds. Groundwater quality data for the previous five years show no exceedances of the NYSDEC GWQS for organic compounds. The analyses do show elevated levels of iron, manganese, sodium, and, to a lesser extent, arsenic, antimony and thallium in on-site monitoring wells. Iron, manganese, and sodium exceed secondary standards; these secondary MCLs are established for aesthetic purposes and are not health based criteria. Iron and manganese are found in most wells at elevated levels in excess of secondary standards in and adjacent to the landfill; however, these constituents are considered to be naturally occurring in the overburden and shallow bedrock in the Hertel Landfill area. Elevated levels are also persistent and localized by the toe of the landfill which may be associated with geochemical changes associated with leachate generation. Arsenic, antimony, and thallium exceedances are localized and sporadic. Results of groundwater analysis from residential wells along Route 44/55 indicate that the iron, manganese, sodium and, to a lesser extent, copper have been detected above their respective secondary MCLs. Consistent with the on-site wells, the maximum detected concentration of iron and manganese did not exceed their respective human health risk-based criteria (RSL). Copper was detected in one private well sample above NYSDEC standards but was not detected in the on-site monitoring wells above the criteria, suggesting that the exceedances of copper in the private wells are not Site-related and may be related to secondary sources (e.g., copper plumbing or brass water fixtures). Institutional controls have now been implemented, as stated above, to prohibit any land use that would impair the effectiveness of the cap, and prohibit installation of wells immediately adjacent to cap. Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives used at the time of the remedy still valid? Some chemical specific toxicity values have changed since the Site was originally assessed. In order to account for changes in toxicity values since the baseline human health risk assessment was performed, the maximum detected concentrations of the contaminants of concern (COCs) identified during the 2010 through 2014 sampling period were compared to NYSDEC GWQS, which are the chemical-specific ARARs established in the ROD. The results indicate that the concentrations of iron and manganese are still elevated and exceed their respective NYSDEC GWQS. The NYSDEC GWQS for iron and manganese are secondary standards which are not based on human health but rather are based on cosmetic or aesthetic effects. Although these numbers are exceeded, when compared to groundwater human health RSL, they do not exceed these values. The exposure assumptions, toxicity data, and screening levels used to complete the August 2003 Baseline Ecological Risk Assessment (BERA) are still valid. . Sediment and surface water quality data are compared to NSYDEC LEL and AWQC standards. Sediment and surface water concentrations for iron and manganese (both upgradient and downgradient) continue to be evaluated and exceed screening levels, but are consistent or lower than pre-remediation

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concentrations and concentrations analyzed in the 2003 BERA. Although ecological risk assessment methodologies have changed since 2003, the results of the 2003 BERA are still valid. Since concentrations in sediment and surface water do not exceed values used in 2003, it is determined that there are no adverse ecological impacts in the wetlands downgradient of the Site. Soil vapor intrusion was evaluated in previous five-year reviews. Over the past five years, there are no organic contaminants that exceed vapor intrusion screening criteria. Therefore it has been concluded that this exposure pathway is not a concern at this Site. The Site and the area surrounding the Site continue to be zoned residential. The remedial action objectives from the 2005 ROD Amendment remain valid. The institutional controls that have been implemented effectively prohibit any land use that would impair the effectiveness of the cap, and prohibit installation of wells adjacent to cap or in areas that could draw in Site-related contamination. Question C: Has any other information come to light that could call into question the protectiveness of the remedy? There is no new information that calls into question the protectiveness of the remedy. Technical Assessment Summary The results of the five-year review have demonstrated that:

There have been no changes in the physical conditions of the Site that would affect the protectiveness of the remedy. The cap is well maintained and there have been no changes to the integrity of the cap.

Data show that, in residential wells, iron and manganese have been detected above secondary NYSDEC water quality standards in several on-site background and potable wells; however, the levels do not present a health threat. All wells, including private wells, will continue to be monitored.

Groundwater data show exceedances of iron and manganese. Studies indicate that these metals are present, or naturally occurring, at elevated concentrations throughout the geologic formation.

Sediment and surface water quality data indicate metal concentrations patterns similar to previous years. The continuing elevated levels of sediment contamination may be due to changes in seepage and runoff conditions along the eastern edge of the landfill. Consequently, sediment/surface water quality along the creek and near the seeps should continue to be monitored.

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Implementation of Institutional Controls has been completed. VIII. Issues/Recommendations, and Follow-up Actions No issues, recommendations, or follow-up actions are warranted. IX. Protectiveness Statement The remedy for the Hertel Landfill Superfund site protects human health and the environment. X. Next Review The next five-year review report for the Hertel Landfill Superfund site is required five years from the completion date of this review.

List of Tables Table 1 Chronology of Site Events Table 2 Documents, Data, and Information Reviewed in Completing the Five-Year Review

Table 1: Chronology of Events

Date

Event

June 1986

Site placed on NPL

September 1989-1991

Remedial Investigation/Feasibility Study (RI/FS) was conducted

September 1991

ROD issued

September 1996

Remedial Design Report approved

November 1996

Preliminary clearing and grubbing of the landfill area

June 1997

Beginning of construction activities

December 1998

Construction of landfill cap completed

December 1998

Site Inspection of landfill cap

May 1999

Remedial Action Report Approved

September 2001

First Five-Year Review completed

October 2002

Groundwater Technical Report completed

July 2004

Post-Decision Proposed Plan issued

July 2004

Upgradient Residential Sampling performed

September 2004

Final Site Inspection conducted

February 2005

Preliminary Close-Out Report documenting completion of Site construction activities approved

January 2005 ROD Amendment

June 2005 Second Five-Year Review completed

April 2010 Third Five-Year Review completed

2005 – to present Long-term monitoring program

Table 2: Documents, Data, and Information Reviewed in Completing the Five-Year

Review Document Title, Author Submittal Date

Final Baseline Ecological Risk Assessment, Arcadis G & M August 2004

Former Hertel Landfill Site, Groundwater Technical Report, Hatch Mott Macdonald

October 2002

Former Hertel Landfill Site Remedial Action Report, Killam Associates

April 1999

Record of Decision, EPA September 1991

First Five-Year Review, EPA September 2001

ROD Amendment, EPA January 2005

Second Five-Year Review, EPA June 2005

Third Five-Year Review, EPA April 2010

Environmental Protection Easements Letter, Hatch Mott MacDonald November 26, 2013

Quarterly Inspection Reports, Hatch Mott Macdonald 2010-2014

Groundwater, Residential, Surface water and Sediment Sampling Data Reports, Hatch Mott Macdonald

2010-2014

2014 Hertel Landfill - Evaluation of Site Monitoring Data Report, Hatch Mott MacDonald

October, 10, 2014

List of Figures Figure 1 Hertel Superfund Site Location Map Figure 2 Hertel Landfill Superfund Site Monitoring Well and Sediment and Surface Water

Sampling Locations Map

Figure 3 Hertel Landfill Site (Landfill Portion) and Private Well Locations Map Figure 4 Groundwater Flow Model Well Exclusion Buffer

Figure 3

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