by:

FOURTH FIVE-YEAR REVIEW REPORT HOOKERS-AREA SITE

NIAGARA FALLS NIAGARA COUNTY, NEW YORK

Prepared by

U.S. Environmental Protection Agency Region 2

New York, New York

September 2014

·Date:

-~k __ Walter E. Mugdan, Director Emergency and Remedial Response Division

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Contents

Executive Summary ......•.....................•...•.•........................................•....•...•..•.•....•...•.•.•...•....•.•.•.•. ii

Five-Year Review Summary Form •..•..............................•......•........•.•..•.•.•..•...•..•.•.•.•.•...•..•...•..• iii

Introduction .................................................................................................................................... 1

Site Chronolo~ ...••.....•..................•....•.....•..............•..........•..••..........•.•..•.•..•.•....•.•.•.•..•.•...•...•.•..•.. 1

Background •••••••••••••.••••.•.•.••••...•....•.....................•..............••.•...•...•.•..•.•••...•••..••..••..•.•.••...•••...•••••••• 1

System Operations/Operations & Maintenance ................•.............•........................................ 11

Progress Since Last Five-Year Review •••••••••••••...•.••.•...••...•...•.....••.•...••...•.•.••...••...•..•••.•.••••.•.••••. 11

Five-Year Review Process •....•.•.......•..............••...•..•.....•..•••.••••••.•.•••••••••••••••••.••••••••••••••...•••••••••••. 12

Administrative Components ••••.•.•••••.•.•.•........•...•..........•...•...•....•.•.•..•.•.•..•••....•......••.......•.•....•.•.•.••• 12

Community Involvement .•.•.••••.•.•••••.•••.••..•.••.•••.•••.•......••••.••••••••••••••••••.••••••.•.•••••••••••.•.••.•.•.•.•..•.•••.• 12

Document Review •••••••.••••.•.•••••••••••••••••••.•••••••••••••.•••.••••.•••••••••••••••••••••.•.•••••••••••••••••••••••••••.••••.•••••.• 12

Data Review •••..........••.•..•.••••..••••••••••••••••••••••••••••••.••.••••••••••••••••••••••••••••••••••••••••.••••••.•••••••••••••••••••• 12

Summary ••••••••••••.••••••••••.••••••.•••••••••••••.••••••••••••••••.•••••.••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••.•.••••• 16

Site Inspection ••••••••••.••••.•.••••.•••••••••.•••.•••.••••.•••••.•...........•.•..•...•................•....•.•..........•..•...•.••..•••••• 17

Interviews •••.•••..••.••...•.••••.••.•.••.•••••••••••••••.••••••••••••••••••••••••.•••••••••••.••••••.••••••.••••••.•••••••••••••••••••••••••••• 17

Institutional Controls Verification ••••••••••••••••••••••.•••.••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 17

Technical Assessment •••....•..•..•...•......•.•.•........................•....•.•........•......•..•..........•.•...•........•.•...... 18

Technical Assessment Summary ..•.....•.•.•.•.•......•.••...••.•.•.•••..••••••••••••••••.•••••••.••••••••••••.••••••••••••.•••..•• 20

Issues, Recommendations and Follow-Up Actions .....•.••..•••.•.•.••...••••.....••....•••.••...•...•.•..•...•.••.. 20

Protectiveness Statement •.............•••.•.•....•.....•••..•...••..•.•••.••••••.•.•.•••••••••••.•.••••.••••••.••••.•.•.•.••.•••••.. 20

Next Review ••••.•.••••.•.••••.•.••••.••••••••.•.•••••....••...•.•.•.•....••.•••.••.••••••••.••••••••.••••.••••••••••.•.•••••...••••...••••.•• 21

Tables ....•..•............•..........•...................•..............................•....•.............••.....••...•..•.•.................•... 22

Attachments ••••••••••••••••••••..•.••..•.•••••••••••.••••••••••••••.••••••.•••••••••••••••••••••••••••••••••••••••••••••••.••••••••••••••••• 24

Figure 1: Site Map with June 2014 Shallow Groundwater Contours ....................................... 24

Executive Summary

This is the fourth five-year review for the Hooker S-Area Superfund site located in Niagara Falls, Niagara County, New York. The purpose of this five-year review is to review information to determine if the remedy is and will continue to be protective of human health and the environment. The triggering action for this statutory five-year review is the previous five-year review for the site, dated September 27, 2009.

This site has ongoing operation, maintenance and monitoring activities as part of the selected remedy. As was anticipated by the decision documents, these activities are subject to routine modification and adjustment. This report did not identify any issues, recommendations or follow-up actions that need to be addressed to ensure the protection of human health and/or the environment. The remedy for the Hooker Chemical S-Area Superfund Site is considered to be protective of human health and the environment.

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Five-Year Review Summary Form

SITE IDENTIFICATION

Site Name: Hooker S-Area

EPAID: NYD980654206

NPL Status: Final

Multiple OUs? No

Has the site achieved construction completion? Yes

REVIEW STATliS

Lead agency: EPA

Author name (Federal or State Project Manager): Kevin Willis

Author affiliation: EPA

Review period: 9/28/2009-9/29/2014

Date ofsite inspection: 817/2014

Type of review: Statutory

Review number: 4

Triggering action date: 9/27/2009

Due date (five years after triggering action date): 9/26/2014

Is~iJes"an~:R~p,rifue~datio~s Identified in" the Five:iY e~r Jleview:; :'"" . ";' ... ' .';;:,. .. :.::c::; F'\f 1·:·;i~~~1~~~:/:1 ,

OU(s): 1 Issue Category: Monitoring

Issue: Determination that NAPL is no longer migrating into Canadian territory should be fmalized to complete this portion of the Remedial Action.

Recommendation: Complete determination ofNAPL migration utilizing the submitted NAPL Tracer Study Report.

Affect Current Affect Future Party Oversight Milestone Date Protectiveness Protectiveness Responsible Party

No No PRP EPA 9/29/2014

lll

I

Operable Unit: 1

Protectiveness Statement:

Protccti' cncss Stat<.·mcnt(s)

Protectiveness Determination: Protective

The remedy is protective of human health and the environment.

Sitt.'" ide Pt·otccti\ cness Statement

Addendum Due Date (if applicable): N/A

Protectiveness Determination: Addendum Due Date (if applicable): Protective N/A

Protectiveness Statement: The site remedy is protective of human health and the environment.

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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, fmdings and conclusions of reviews are documented in the five-year review. In addition, five­year 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 HookerS-Area Superfund site (site), located in Niagara Falls, Niagara County, New York. This review was conducted by United States Environmental Protection Agency (EPA) Remedial Project Manager (RPM), Kevin Willis. The five-year review was conducted pursuant to Section 121 (c) of the Comprehensive Environmental Response, Compensation, and Liability Act, 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 ofthe site file.

The triggering action for this statutory review is the date of the previous five-year review for the site, which is September 27, 2009. A five-year review is required at this site due to the fact that hazardous substances, pollutants or contaminants remain at the site above levels that allow for unlimited use and unrestricted exposure. The site consists of one operable unit, which is addressed in this five-year review.

Site Chronology

See Table 1 for the site chronology.

Background

The site is an eight-acre industrial landfill owned by the Occidental Chemical Corporation (OCC). It is located at the southeast comer of OCC's Buffalo Avenue chemical plant in Niagara Falls, New York, along the Niagara River. Adjacent to the landfill is the City of Niagara Falls (City) drinking water treatment plant (DWTP). The Province of Ontario, Canada, is located across the Niagara River, a distance of approximately two miles. The site is located in a heavily industrialized area of Niagara Falls. There is a residential community of approximately 700 people within 1/4 mile northeast of the site. The DWTP serves an estimated 70,000 people.

Geology/Hydrogeology

The landfill lies atop approximately 30 feet of soil, clay, till and manmade fill on an area reclaimed from the Niagara River. Beneath these materials is fractured bedrock.

History of Contamination and Initial Response

ace disposed of approximately 63,000 tons of chemical processing wastes into the landfill from

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194 7 to 1961. The landfill also was used by OCC for disposal of other wastes and debris, a practice that ended in 1975. Two lagoons for nonhazardous waste from plant operations were located on top of the landfill and were operated under New York State permits until1989, when OCC discontinued operating these lagoons.

During an inspection of the DWTP in 1969, chemicals were found in the bedrock water intake structures of the Niagara Falls DWTP. In 1978, sampling of the structures and bedrock water intake tunnel revealed chemical contamination.

On December 20, 1979, the United States Department of Justice, on behalf of the EPA, filed a civil action (Civil Action No. 79-988) against the Hooker Chemicals & Plastics Corporation, now OCC, alleging an "imminent and substantial endangerment" at the site. Other parties to join the lawsuit were the State ofNew York (as a plaintiff) and the City (as a defendant). The civil action was filed pursuant to Section 1431 of the Safe Drinking Water Act, Section 7003 of the Resource Conservation and Recovery Act (RCRA), Section 504 of the Clean Water Act and the common law of nuisance. The site was included on the National Priorities List (NPL) on September 1, 1983.

The civil action led to two negotiated settlement agreements for the remediation of the site and the adjacent DWTP. The first settlement agreement, entitled "Stipulation and Judgment Approving Settlement Agreemenf' (Settlement Agreement), was signed on January 10, 1984 and approved and entered by the Court on April15, 1985. The Settlement Agreement specified a containment remedy for the landfill and remediation of the adjacent DWTP. Prior to approval, the Court conducted a hearing during which the Province of Ontario, Canada and the Ministry of the Environment of the Province of Ontario, Canada, as intervening parties, challenged the remedy set forth in the Settlement Agreement. The Court rejected that challenge and, by finding the selected remedy to be protective of public health and the environment, entered the Settlement Agreement. United States v. Hooker Chemicals & Plastics Corp., 607 F. Supp. 1052 (W.D.N.Y. 1985). The Court's decision was affirmed by the United States Court of Appeals for the Second Circuit on appeal. United States v. Hooker Chemical & Plastics Corp., 776 F.2d 410 (2nd Cir. 1985).

Basis for Taking Action

During initial enforcement activities, since the full extent of chemical migration from the landfill was not known, the Settlement Agreement included a process for conducting additional remedial investigations and determining what, if any, additional response actions were necessary. The process to evaluate various remedial alternatives was called a Requisite Remedial Technology (RRT) Study (i.e., the equivalent of a CERCLA feasibility study). Based on the results of the additional investigations and the RRT Study, which were performed by OCC in the late 1980s, the parties negotiated a second agreement, entitled "Stipulation on Requisite Remedial Technology Program" (RRT Stipulation) to remediate those areas of contamination at the site which would not be addressed by the 1985 Settlement Agreement. The RRT Stipulation outlined a remedy which was conceptually consistent with the original remedy, but one that expanded and improved upon that remedy. The RRT Stipulation was lodged with the Court on September 21, 1990 and approved and entered by the Court on April 12, 1991. The RR T Stipulation was incorporated into, supplemented and modified the 1985 Settlement Agreement.

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Remedial Actions

A comprehensive remedy for the site is being implemented in accordance with the 1985 Settlement Agreement, as amended by the 1991 RRT Stipulation. It is being overseen jointly by EPA and the New York State Department of Environmental Conservation (NYSDEC) and the New York State Department of Health (NYSDOH) in accordance with a 1984 Memorandum of Understanding. The remedial action consists of multiple remedial systems and programs that are designed to contain aqueous phase liquid (APL) and nonaqueous phase liquid (NAPL) chemicals at the site, thereby preventing the further migration of those chemicals eastward toward the City's property and southward into and under the Niagara River. They are also designed to collect NAPL chemicals to the maximum extent practicable.

The remedial systems and programs consist of the following: (A) the S-Area Overburden Remedial Systems; (B) the S-Area Bedrock RRT System; (C) the Remedial Waste Management Program; and (D) the DWTP Remedial Program. The remedy objectives, components, and implementation activities are discussed separately for each system below.

A. S-Area Overburden Remedial Systems

The objectives established for the Overburden Remedial Systems are to: (1) contain APL and NAPL; (2) maximize the collection ofNAPL; and (3) minimize the migration of chemicals toward the City's DWTP. The Overburden Remedial Systems consist of a slurry cut-off wall (Barrier Wall), a Drain Collection System (DCS), a network of site Containment Purge (pumping) Wells and Capping.

Barrier Wall

The Barrier Wall is designed to encompass the entire landfill and those areas adjacent to the landfill where S-Area NAPL chemicals migrated through overburden soils to the Niagara River and the former DWTP.

The Barrier Wall is designed to remain indefinitely as an effective barrier to chemical migration. To that end, a materials compatibility testing program was performed as part of the design between 1989 and 1993 to ensure that the Barrier Wall would not be degraded by contact with site chemicals. EPA and NYSDEC approved the testing program in April 1993 and the Barrier Wall design in June 1993.

Construction of the northern, southern and western portions of the Barrier Wall was completed in 1995. Because the planned alignment of the eastern portion of the wall crossed the City's former DWTP, which was the City's primary source of drinking water at that time, the eastern wall could not be constructed until after the new DWTP was built and on-line and the former DWTP decommissioned. The replacement DWTP was fully operational by the end of February 1997 and the eastern wall was completed in June 1998 (see also Eastern Barrier Wall Construction under DWTP Remedial Program, below). The barrier wall does not require maintenance and its effectiveness is monitored as part of the quarterly monitoring program.

Drain Collection Svstem (DCS)

The DCS is comprised of a network of drains located in overburden soils within the Barrier Wall

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and sloped to a central collection well (Wet Well A) for recovery of groundwater and NAPL. Each drain consists of a perforated pipe located at the bottom of a stone-filled trench. The DCS is designed to maximize the collection of groundwater and NAPL within the Barrier Wall. It is to be operated along with the site Containment Purge Wells to achieve an inward hydraulic gradient across the Barrier Wall. It is operated to create and maximize an upward hydraulic gradient from the underlying bedrock into the overburden soil within the area encompassed by the Barrier Wall. This upward gradient is designed to prevent the further migration of APL and NAPL chemicals downward into the underlying bedrock. To maximize the upward gradient, the water level within the DCS is to be maintained at the lowest elevation of the system (i.e., the pipe invert elevation at Wet Well A). The DCS design was approved by EPA in June 1994. Construction work commenced in October 1994 and the DCS was completed in June 1995.

During testing and operational start-up in 1996, the DCS failed to operate or function as designed. The DCS was designed with the expectation of pumping groundwater from Wet Well A at a rate of approximately 30 gallons per minute (gpm) to dewater the system. However, only a pumping rate of between 13 and 18 gpm could be achieved at Wet Well A and the water levels throughout most of the system did not show any response to pumping. OCC continued to operate the system at such pumping rates until October 1997, when it conducted an investigation to determine the nature of the problem. This investigation, which was completed on January 8, 1998, revealed that the pipes were either obstructed or crushed at multiple locations in every segment of the drain system. EPA and NYSDEC met with OCC and its contractors on April15, 1998 to discuss the problem and possible corrective actions.

Throughout most of 1998, OCC attempted to enhance the performance of the damaged DCS with additional pumping. Those efforts were unsuccessful and EPA and NYSDEC subsequently directed OCC to replace the system in 1999. OCC's contractors began construction on July 12, 1999 using both horizontal directional drilling and open-cut trenching methodologies. The work was completed in March 2000. The DCS continues to operate and is maintained by OCC contractors. Monitoring of this system is done as part of the quarterly sampling program.

Site Containment Purge Wells

The design of the site Containment Purge Wells network was included as part of the plans contained in Appendix I of the RRT Stipulation. The installation of the site Containment Purge Wells commenced in late 1993. Well installation was completed in 1994 and the force mains for piping the collected APL and NAPL (i.e., leachate) to the on-site Leachate Storage and Handling Facility were completed in 1995. The wells were pump tested in early 1996 and full-scale pumping operations commenced in August 1996. Several of the pumping wells were designated as NAPL recovery wells, based on the pump-testing results. The site Containment Purge Wells and their effectiveness is monitored under the quarterly sampling program.

Capping

The purpose of capping the landfill is to provide a physical barrier for the protection of human health and the environment. It is also to minimize the infiltration of precipitation and, hence, the volume of leachate generated in overburden soils within the Barrier Wall. Reducing the volume of leachate within the landfill will enable the DCS and site Containment Purge Wells to pump smaller volumes of liquids in creating and maintaining the required inward and upward hydraulic gradients within the Barrier Wall.

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The site capping program consists of a Perimeter Cap and Landfill Cap. Due to the amount of investigative and subsurface remedial work to be conducted over the site, the Perimeter Cap was constructed in two phases.

The first phase of the Perimeter Cap was designed to cover the areas adjacent to the landfill which are within the Barrier Wall, excluding the Robert Moses Parkway, the median of the parkway and the area south of the parkway, along the Niagara River. EPA and NYSDEC approved the design of this phase of the Perimeter Cap construction on December 22, 1995. The Perimeter Cap is comprised of an asphalt cap (for parking) on the north and west perimeters of the landfill and a composite liner on the south perimeter. The composite liner consists of a 30-millimeter (mil) thick geomembrane liner, overlain by three feet of compacted clay, 18 inches of loam, 6 inches of topsoil and a vegetative cover. A permanent security fence surrounds the Perimeter Cap. This phase of the cap construction began on October 2, 1995 and was completed on September 19, 1996.

The second phase of the Perimeter Cap consists of a composite cover for the area inside of the eastern Barrier Wall and a clay cap for the remaining portion of the property. EPA and NYSDEC approved the cap design on November 6, 1997. Cap construction commenced in April 1998, the construction was completed in October 2001, and the final inspection was conducted in April2002. This phase of the Perimeter Cap is discussed in further detail in the section which describes the remedial work performed on the DWTP remedial program.

The Landfill Cap was designed as a composite cover system that includes 24 inches of compacted clay, overlain by a 60-mil flexible membrane liner, a geocomposite drainage fabric, 18 inches of barrier protection soil, six inches of topsoil and a vegetative cover. Construction of the cap began in July 2000. Construction of the Landfill Cap was largely completed in October 2001 and the final inspection was conducted in May 2002. The cap is maintained by OCC contractors. Maintenance includes mowing and repair of the fence.

B. S-Area Bedrock RRT System

The objectives for the Bedrock RRT System are: to contain APL and NAPL hydraulically within the existing area of bedrock NAPL contamination (i.e., bedrock NAPL plume), to prevent further NAPL migration in the bedrock under the Niagara River, and to collect NAPL within this plume to the maximum extent practicable.

The Bedrock RRT System is designed to remediate three distinct water-bearing zones within the bedrock aquifer: (1) a Shallow Bedrock Zone consisting of the more-highly fractured upper 30 feet of bedrock, (2) an Intermediate Bedrock Zone between the depths of approximately 30 and 1 00 feet below the top of bedrock, and (3) a Deep Bedrock Zone between the depths of approximately 100 and 150 feet below the top of bedrock. To achieve its objectives, the Bedrock RRT System is comprised of groundwater pumping wells, NAPL recovery wells, and monitoring wells for each of the three zones. A network of force mains is used for piping leachate from the wells to the on-site Leachate Storage and Handling Facility.

The Final Bedrock RRT System Design report was submitted to EPA and NYSDEC on February 9, 2001. This report was approved on June 19, 2001 and the construction for this portion of the work was completed June 2002. This system has undergone minor modifications to optimize the

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system operation and maintenance regularly.

C. Remedial Waste Management Program

The Remedial Waste Management Program was developed to address all solid and semi-solid waste materials, APL and NAPL generated during the construction and operation of the site remedial programs. This program includes: ( 1) the disposal of solid and semi -solid remedial wastes atop the landfill, (2) the construction of the Leachate Storage and Handling Facility, (3) the construction of a water treatment facility to treat APL chemicals (hereinafter the "APL Treatment Facility"), and (4) the characterization ofS-Area NAPL and obtaining the authorization to incinerateS-Area NAPL at the Liquids Hazardous Waste Incinerator (Liquids Incinerator), located at OCC's Buffalo Avenue Chemical Plant.

Remedial Waste Disposal

All solid and semi-solid waste materials generated during performance of the remedial work have been placed atop the landfill in accordance with approved waste staging plans. Semi-solid wastes were first stabilized prior to placement. Waste was placed in individual lifts within constructed waste cells, which were stacked on top of each other to accommodate waste placement and to match final grading plans for the landfill. The bottom of the waste cells were lined with compacted clay prior to waste placement and all wastes were covered with clay.

Leachate Storage and Handling Facility

The on-site Leachate Storage and Handling Facility is designed to store all the leachate collected by the site remedial systems prior to treatment. Construction work was substantially complete in October 1992. EPA and NYSDEC inspected the facility on May 6, 1993 and June 25, 1993.

Following the performance of pumping tests on the Prototype Bedrock System for the Shallow Bedrock Zone in 1992, it was determined that an additional tank would be needed for storing APL. The additional tank was constructed at the Leachate Storage and Handling Facility from August 1993 to January 1994. The facility currently receives and stores all leachate being collected by the remedial systems in operation at the site.

AP L Treatment Facility

The APL Treatment Facility utilizes granular activated carbon for treating APL generated by the site remedial systems. The maximum treatment capacity is approximately 300 gallons per minute (gpm) or roughly half a million gallons per day (gpd). The treated water is discharged to the Niagara River via a permitted outfall.

The APL Treatment Facility design was approved by EPA and NYSDEC in September 1992 and construction began in October 1992. Construction was substantially complete in June 1994 and testing and start-up operations were conducted at the facility in late 1994/early 1995. The facility was fully operational by March 1995. All waters collected by the operating remedial systems and decanted from the Leachate Storage and Handling Facility are currently sent to the APL Treatment Facility for treatment prior to discharge to the Niagara River.

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NAP L Characterization and Authorization to Incinerate

OCC collected representative NAPL samples from the site in 1992 for characterization and to obtain authorization to incinerate. EPA and NYSDEC permitting authorities approved the burning ofS-Area NAPL at OCC's Liquids Incinerator in 1993. The results of trial burns conducted by OCC in 1994 and 1995 indicated that the NAPL was a difficult waste to burn due to a high ash and chlorine content and a low British thermal unit (BTU) value. OCC elected not to burn S-Area NAPL at the Liquids Incinerator, but continued to store it on site while assessing the availability of permitted commercial incinerators. In 1999, OCC entered into an agreement with a commercial facility located in Deerpark, Texas, to incinerate the S-Area NAPL. This facility was used until permit changes were approved which allowed OCC to use the adjacent OCC Main Plant NAPL Incineration Unit for destruction of the site's NAPL beginning in April 2001. To date, approximately 200,000 gallons ofNAPL have been treated. Approximately 1,100 gallons ofNAPL per month are sent for incineration.

D. Drinking Water Treatment Plant (DWTP) Remedial Program

This program consists of the construction of a new D WTP for the City at a new location and the closure and remediation of the former DWTP and property. The closure and remedial programs selected for the former DWTP include plant demolition, construction of the eastern portion of the site Barrier Wall, construction of an APL Containment and Collection System to prevent APL from flowing into the Niagara River and eastward toward the City's property, a program to remove NAPL within the bedrock raw water intake structure, the securement of the overburden and bedrock raw water intake structures, and capping. Two investigations were also conducted at the former DWTP property; the City's investigation of the eastern portion of the former DWTP property (Eastern Portion) and OCC's NAPL investigation.

New Drinking Water Treatment Plant

For the siting of the new DWTP, the City selected a 25.8-acre parcel ofland owned by the New York Power Authority (NYPA) and located adjacent to the former DWTP along Buffalo Avenue (hereinafter the "Buffalo A venue site"). At that time, the Buffalo Avenue site was listed on the NYSDEC's Registry oflnactive Hazardous Waste Sites and classified as a Class 2A site. This classification signifies that sufficient data do not exist to allow NYSDEC to evaluate whether or not the site poses a threat to human health and the environment. The City completed a site investigation that showed the Buffalo A venue site to be relatively clean, with the exception of a one-acre parcel along the western boundary of the property. Based on the results of that investigation, the City petitioned NYSDEC to delist the site. NYSDEC notified the City on January 21, 1992 that it supported the petition for delisting all but the one-acre parcel of land. The City completed acquisition of the Buffalo Avenue site from NYPA on June 5, 1992.

In accordance with the RRT Stipulation, EPA, concurrent with NYSDOH, had approval authority of the DWTP design plans and specifications as they related to any systems and structures intended to prevent future contamination of the City's drinking water supply. As part of the· design review process, EPA requested that the entire raw water intake system be designed with a second level of protection against contamination. To provide such protection, the City designed the intake system with a Prestressed Concrete Cylinder Pipe (PCCP) consisting of a steel, cylindrical pipe within prestressed concrete. The PCCP was placed inside the bedrock tunnel from the intake shaft to the low-lift pump station. Additionally, as an added layer of

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protection, the annular space between the pipe and the intake tunnel wall was also grouted with a light-weight concrete.

The design for the new DWTP was approved by NYSDOH on November 19, 1993 and EPA on December 9, 1993. The DWTP is designed with a maximum daily capacity of35 million gpd, with a peak hydraulic capacity of 52 million gpd. Average daily demand in the early 1990s was approximately 25 million gpd. Construction of the new plant by the City's contractors commenced on August 22, 1994. NYSDOH issued an "Approval of Completed Works" on February 21, 1997.

During the spring 2004 construction of drying beds used for processing the sludge regularly generated by the treatment of drinking water, volatile organic contamination (VOC) contamination was discovered in the soils being excavated. This contaminated soil was addressed by the DWTP facility and is not considered part of the S-Area site. Likewise, the continued operation, maintenance and monitoring of the DWTP is not part of the CERCLA action and has not been addressed in this review.

Demolition ofFormer Drinking Water Treatment Plant

The City's contractor commenced demolition of the former DWTP on April3, 1997. The above­ground structures were demolished in place, with the underground reservoirs and sedimentation basins used as receptacles for debris. Asbestos waste materials were removed from the two filtration plants prior to demolition and transported to the S-Area landfill for disposal in accordance with federal and state requirements for handling and disposal of asbestos waste. The filter media was also removed from a filtration plant prior to demolition and disposed at the S­Area landfill in accordance with the RRT Stipulation. Demolition work was completed in December 1997.

Eastern Barrier Wall Construction

EPA and NYSDEC approved the design for the eastern Barrier Wall on November 6, 1997. Construction activities commenced on February 2, 1998 with the severance and plugging of all underground utilities along the planned alignment of the wall. The plugging of severed utilities which lie outside of the eastern Barrier Wall with grout eliminated any potential pathway for NAPL migration. Slurry wall construction commenced on May 18, 1998 and continued into June 1998. The eastern Barrier Wall was tied into the northern and southern portions of the Barrier Wall. With the completion of the eastern portion of the wall, all four sides of the Barrier Wall were completed. The barrier wall does not require maintenance and its effectiveness is monitored under the S-Area Bedrock RRT System.

AP L Containment and Collection Program

The APL Containment and Collection Program is designed to contain and collect APL chemicals which are present in the groundwater beneath the former DWTP property, thereby preventing those chemicals from migrating into the Niagara River and eastward toward the City's property. The APL is contained and collected by an overburden drain collection system located along the southern edge of the property. The collection system consists of a perforated pipe located at the bottom of a stone-filled trench and sloped to a collection well located at one end of the drain. The collected groundwater is piped first to the S-Area Leachate Storage and Handling Facility

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and, subsequently, to the S-Area APL Treatment Facility for treatment. The RRT Stipulation specified that the drain collection system was to be installed across the western portion of the property.

EPA and NYSDEC approved the design for the drain collection system on November 6, 1997. The construction work was substantially complete in December 1998 and start-up operations commenced in January 1999.

NAPL Removal (rom Bedrock Raw Water Intake Tunnel

The purpose of the NAPL Removal Program is to inspect the bedrock raw water intake tunnel of the former DWTP for the presence ofNAPL, and remove any collectable quantities ofNAPL from the tunnel prior to grouting. In April1996, OCC's contractor performed a video inspection of the first 1,060 feet of the bedrock tunnel. The inspection revealed the presence of collectable quantities ofNAPL approximately 860 feet into the tunnel from the Shore Shaft. NAPL removal activities were conducted in March 2000 prior to the Tunnel Grouting action. No further operation, maintenance or monitoring is required.

Securement o(Raw Water Intake Structures

A program was designed to secure the former DWTP's overburden and bedrock raw water intake structures. The overburden intake, a 48-inch diameter emergency intake, was closed by severing the pipe at the south property line. The overburden intake structure was removed from the Niagara River coincident with the bedrock intake structures in August 2000.

The securement of the bedrock intake tunnel network, including the two shaft intakes and shore shaft was performed by grouting the entire system with cement/bentonite grout. The bedrock tunnel is located over 75 feet below ground surface. It is approximately six feet wide, seven feet high, and over 5,000 feet in total length. The bedrock intake structures, which sit atop the intake shafts, were removed from the Niagara River and backfilled with grout.

Mobilization of the Tunnel Grouting field activities occurred in July 2000. The grouting proceeded as designed with exception of a portion of the tunnel underlying Buckhorn Island. It was confirmed by borings that the tunnel was grouted floor to ceiling for the majority of the extent ofthe tunnel with the exception of a length of tunnel at a distance of approximately 3,800 feet from the shore shaft. The void extends from 120 to 500 feet from this point under Buckhorn Island. The final segment beyond this point was also shown to be properly grouted.

EPA and NYSDEC agreed in an April 17, 2002 meeting that the portion of the tunnel that had not been grouted was not a threat to the migration ofNAPL from the site and that it was unnecessary to grout this void. A monitoring well was installed to sample the water in the ungrouted portion of the tunnel and is being monitored as part of the bi-annual Shallow Bedrock Sampling Program. Monitoring results in the well indicated that water in this ungrouted portion of the tunnel was contaminated with VOCs. It was agreed that sodium permanganate would be injected into the tunnel void to address the contamination. The injections of the sodium permanganate began in March 2004 and the subsequent monitoring data have demonstrated that this action has been effective. Four injections ofpermanganate were done, the last being August 2006, when EPA and OCC agreed that no further injections were necessary. The well continues to be monitored as part of the Quarterly Sampling Plan.

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Capping

The cap consists of a composite cover for the area inside of the eastern Barrier Wall and a clay cap for the remaining portion of the property. The composite cover is comprised of a 40-mil geomembrane liner, overlain by twelve inches of compacted clay, twelve inches of loam, six inches of topsoil and a vegetative cover. The geomembrane liner overlaps the top of the eastern Barrier Wall and abuts 53rd Street, the road separating the former DWTP property from the S­Area landfill. The clay cap for the remaining portion of the property is the same as the composite layer, but without the underlying geomembrane. Drainage swales and catch basins line the eastern and western perimeter of the cap. The swales and catch basins along the western perimeter are designed to drain into an existing 24-inch storm sewer.

EPA and NYSDEC approved the cap design on November 6, 1997. Cap construction commenced in April 1998, the construction was completed in December 1998, and the final inspection was conducted in April 2002. Maintenance of this area is part of the overall cap maintenance program. ·

Eastern Portion Study

In accordance with the RRT Stipulation, the Eastern Portion of the former DWTP property was addressed by the City under the State ofNew York's Inactive Hazardous Waste Disposal Site Program. In 1995 and 1996, the City performed the Eastern Portion Study to determine the nature and extent of contamination and whether such contamination poses a threat to human health and the environment The results revealed the presence of S-Area chemicals in the groundwater beneath the Eastern Portion. The DWTP drain collection system was extended across the Eastern Portion to contain and collect the S-Area chemicals present in the groundwater.

At the same time of the Eastern Portion Study, the City also performed an investigation of the one-acre parcel located at the new DWTP. The one-acre parcel was determined to be contaminated but not related to the S-Area. This parcel has been listed as a separate State of New York Inactive Hazardous Waste Disposal Site and is not considered to be part of the S-Area site and is not covered by this review.

DWTP NAPL Investigations

During the installation of the S-Area Prototype Bedrock System monitoring wells in 1997, NAPL was encountered in an area of the bedrock at the former DWTP which was not previously identified. An investigation was performed by OCC to redefme the extent ofNAPL. Bedrock wells were installed on both the western and eastern portions of the property. The results showed the presence ofNAPL in the Shallow Bedrock Zone extending as a linear, "fmger-like" feature eastward approximately 300 feet from the previously defined NAPL plume boundary. OCC has installed two pumping wells along the NAPL finger and discharge lines to the S-Area Leachate Storage and Handling Facility. These wells are currently in operation to control the APL and NAPL plumes hydraulically at this portion of the property and collect NAPL. A hydraulic monitoring program is underway to evaluate the long-term effectiveness of this system in containing the APL plume at the former DWTP property.

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System Operations/Operations & Maintenance

There are five sampling programs at S-Area - one in the overburden and four in the bedrock. The overburden sampling program (V -Area Chemical Monitoring Program) is performed voluntarily on an annual basis at 22 monitoring wells within the former city DWTP. Samples are analyzed for site-specific VOCs, semi-volatile organic compounds (SVOCs), pesticides, and organic acids, and total organic carbon (TOC) and total organic halides (TOX).

The bedrock sampling programs include the environmental monitoring program (EMP), shallow bedrock chemical program (SBCP), intermediate/deep chemical program (IDCP), and NAPL tracer program (NTP). The EMP is performed quarterly at eight monitoring wells. Samples are analyzed for site-specific VOCs, SVOCs, and pesticides, and dioxin/furans. The SBCP is performed annually at six inner-ring monitoring wells and semi-annually at 22 middle and outer­ring monitoring wells. Samples are analyzed for site-specific VOCs, SVOCs and TOX. The IDCP is performed annually at eight intermediate monitoring wells, four deep monitoring wells, and one monitoring well installed in the former DWTP intake tunnel. Samples are analyzed for site-specific VOCs, SVOCs and TOX. The NTP is performed annually at 13 wells. Both APL samples and NAPL samples (if present) are collected.

The site Containment Purge Wells well network is monitored as part of the quarterly sampling program. Wells have been added to this network over time if they showed appreciable NAPL production.

Maintenance of the systems is an ongoing effort. Extraction wells are refurbished or replaced when flow into the well decreases substantially. Trends of contaminant inflow within the containment area are continually evaluated to determine what modifications to the extraction and collection systems can be made.

Progress Since Last Five-Year Review

The last five-year review, completed in September 2009 found the remedy to be protective. The 2009 five-year review had the following recommendations:

The site requires monitoring, operation, and maintenance activities to ensure the effectiveness of the remedy; OCC and its contractors have successfully performed these activities to date, such that the remedy is operating as intended and is protective of human health and the environment. The following suggestions should be considered in order to improve the effectiveness of the systems:

- The site monitoring plan should be periodically reviewed and adjusted. Adjustments could include installation and sampling of additional monitoring wells in order to support existing information suggesting that off-site migration of APLfrom S-Area through bedrock zones beneath the Niagara River is not occurring. These wells should be screened in both the intermediate and deep bedrock zones. Existing or newly-installed wells should be considered for use in increased monitoring of potential off-site contamination in conjunction with the NAP L Tracer Study.

-A capture zone analysis should be performed to provide additional support for the determination that the groundwater capture system is working effectively.

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During the past five years EPA, NYSDEC and OCC have discussed efforts needed to verify that NAPL migration to the Niagara River is not occurring. Currently, OCC believes that data and lines of evidence exist that support the notion that the NAPL under the Niagara River has reached its point of furthest migration and may even be receding back towards the S-Area site. OCC is developing a new "multiple point of evidence" report for NYSDEC and EPA's review in the winter of2014.

Based on a review of the site monitoring plan, the presentation of site monitoring data may be adjusted in the future due to provide data in a more efficient format.

During this five-year reporting period, the semi-annual sampling of the site monitoring wells has been performed and regular maintenance of the remedial systems has been performed in accordance with the approved Hooker S-Area Operations and Maintenance Plan.

Five-Year Review Process

Administrative Components

The five-year review team included Kevin Willis (RPM), Charles Nace (EPA - Human Health and Ecological Risk Assessor), Edward Modica (EPA - Hydrogeologist), Michael Basile (EPA -Community Involvement Coordinator (CIC)).

Community Involvement

The EPA CIC for the Hooker S-Area site, Michael Basile, published a notice on the City of Niagara Falls webpage on May 23,2014, notifying the community of the initiation of the five­year review process. The notice indicated that EPA would be conducting a five-year review of the remedy for the site to ensure that the implemented remedy remains protective of public health and is functioning as designed. It was also indicated that once the five-year review is completed, the results will be made available in the local site repositories.

Document Review

The documents, data and information which were reviewed in completing this five-year review are summarized in Table 2.

Data Review

Groundwater Chemical Monitoring

Groundwater data are collected from a network of monitor wells located in and adjacent to the S­Area Landfill and within the V-Area that lies outside and east of the Landfill barrier wall. As per the RTT, different long-term monitoring programs have been established to evaluate the chemical concentrations in the APL in groundwater, the presence ofNAPL in groundwater, and the effectiveness of purge/recovery wells in containing APL/NAPL migration relative to historic S-Area NAPL plume footprints. The monitoring programs focus on different aquifer zones beneath S-area; hence, monitoring wells are screened in the overburden aquifer and at various depths within the bedrock aquifer (designated as shallow, intermediate and deep) to address

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monitoring needs at all levels of the aquifer. The discussion of groundwater data in this section focuses on the data collected during this past five year period (2009-2014).

Overburden

A chemical sampling monitoring program was established for V -Area and the former DWTP area in the overburden aquifer to evaluate water-quality conditions and to monitor chemicals that move toward the DWTP and toward the Niagara River. The wells are generally aligned along the eastern and western boundaries of the former DWTP property as well as along the site barrier wall. The ambient overburden groundwater flow direction across V -Area is from north to south toward the Niagara River; S-Area chemicals migrate with groundwater southward. (The V-Area drainage collection system was installed across this groundwater flow path to intercept overburden groundwater APL and prevent potential migration of S-Area chemicals to the Niagara River.)

For the last five years (2009-2014), 13 wells have been sampled on an annual basis. Generally, concentrations of total VOCs (TVOCs) in each of the wells fluctuated around an average value with no apparent trends observed. An exception to this trend was noted for concentrations in well OW597R, located near the southeastern side of former DWTP, where TVOCs increased from 1.4 parts per billion (ppb) in 2011 to 171 ppb in 2012 and increased slightly in 2013 to 186 ppb. The reason for the increase is not clear, but will be further evaluated with data from the next scheduled sampling event. A map with well locations (Figure 1) can be found in the appendix of this report.

Shallow Bedrock

A chemical monitoring program was established to evaluate water-quality conditions in the shallow zone bedrock. The objective is to monitor VOC/semi-VOC concentrations, on a semi­annual basis, in the APL inside and outside of the S-area shallow bedrock NAPL plume. The ambient groundwater direction in the shallow bedrock is from the southeast and moves northwest. The monitoring wells are located around the fringe of the historic NAPL plume footprint (in the shallow bedrock) and are aligned in roughly three concentric 'arcs' along its western-northern-eastern boundaries.

Samples collected from six outer arc wells (in clockwise order: OW414D, OW223, OW805, OW411D, OW220 and OW677) show the lowest concentrations ofTVOCs compared to monitoring wells closer to or within the NAPL plume. For the last five years, the average TVOC concentration for all samples collected in all outer wells was approximately 463 ppb, less than a third of the average TVOC concentration collected in wells closer to and within the NAPL plume. In general, the TVOC concentrations fluctuate around an average value, but show no apparent trends.

Monitoring wells that comprise the middle arc are located closer to the edge of the shallow bedrock NAPL plume than the outermost wells. TVOC concentrations in these wells are higher than the outermost wells; the average concentration of samples in all middle arc wells over the last five years was 1,672 ppb. The TVOC concentrations fluctuated around an average value and were consistent with historic concentrations; no long-term trends were shown. The lowest TVOC concentrations were observed in well OW672 west of S-Area, with an average of 18.5 ppb and a minimum of 6 ppb reported for the five-year period; the highest concentrations were observed in

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OW674 also located west of S-Area, with an average of7,358 ppb and a maximum of21,148 ppb reported for the period. The average of the past five years of data showed that Well OW243 decreased to 3 ppb compared to the average concentration of 528 ppb of the previous five-year review period, while well OW670 decreased to 46 ppb compared to the average concentration of 10,691 ppb: The wells are not close together and the cause of the abrupt decrease is not known. TVOC concentrations in wells OW240R and OW648 are, on average, lower than most other wells in this group (129 ppb and 28 ppb, respectively) except for well OW670. These wells are located close to the Niagara River on either side of the NAPL plume.

Monitoring wells that comprise the inner arc are located closest to the boundary of S-Area Landfill. TVOC concentrations in these wells have been, on average, the highest of the 'concentric arc' wells; the average concentration for all inner wells sampled over the last five years was 3,178 ppb. For the most part, the TVOC concentrations fluctuate around an average value with no long-term trends shown. However, the highest concentrations were reported for well OW806, located near the Niagara River, at an average of 16,581 ppb for the five-year period and at a maximum of32,740 ppb reported in 2010. Over the last three sampling events, the concentrations in this well have trended downward relative to the concentrations reported for 2010, down to 3,827 ppb in 2013.

TVOCs are composed of various isomers oftrichlorobenzene (TCB), dichlorobenzene (DCB), dichloroethene (DCE), as well as benzene, chlorobenzene (CB), tetrachloroethene, trichloroethene (TCE), and vinyl chloride (VC). Also present are the polymorphs of tetrachlorobenzene, hexahlorobenzene, hexachlorobutadiene, hexachloro-cyclopentadiene, and octachlorocyclopentene (PCBs ). In general, the chemical constituents CB, TCB, DCB, DCE, VC, and PCB make up the dominant fraction of TVOCs found in monitoring wells. For example, based on results for the May 2013 sampling event, TVOCs in well OW230 consisted of 21%TCB, 10% DBC, 14%CB, 35% cis-1,2-DCE, 6% VC, 3% TCE, 2% 1,2,3,4-DCB, and 9% other TVOCs. In some wells, the chemical constituents cis-1,2-DCE and VC make up the dominant fraction ofTVOCs, suggesting that some reductive dechlorination may be taking place in parts of the aquifer.

Intermediate/Deep Bedrock A chemical monitoring program was also established for the intermediate and deep zone bedrock. The objective of the program is to monitor the chemical concentrations in APL outside the S-area intermediate and deep bedrock NAPL plumes. Eight wells are used to monitor conditions in the intermediate zone whereas four wells monitor the deep bedrock zone. In general, the TVOC concentrations in intermediate-zone wells fluctuate around an average value, consistent with historical concentrations and show no trends. TVOC concentrations ranged from no detection (in several wells) to as high as 990 ppb (in OW634 reported for October 2012). Five of the intermediate-zone monitoring wells are located around the fringe of the historic intermediate bedrock NAPL plume footprint along its western-northern-eastern boundaries (in clockwise order: OW693, OW634, OW694, OW685R, and OW800). No detection or only trace levels ofTVOCs were observed in wells OW693 and OW800, wells located on either side of S-Area and adjacent to the Niagara River. The average TVOC concentration for well OW694, located just north of the NAPL plume but south of the treatment facility, was 118 ppb, whereas for well OW685R, located to the northeast of the plume, the average concentration was 122 ppb. Well OW634, located on the west edge of the NAPL plume, reported concentrations that averaged 620 ppb, the highest of the group of wells that 'encircle' the intermediate bedrock NAPL plume. No detections were observed in wells OW412C, OW807

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and OW679located hundreds of feet north and east of the plume.

The wells OW630, OW642, OW643 and OW687 encircle the deep bedrock NAPL plume and are used to monitor organic concentrations in the deep-zone bedrock. The TVOC concentrations fluctuate around average values compared to concentrations first reported in 2002 with no long­term trends. The highest concentrations were reported for OW630, located approximately 300 feet southeast of the NAPL plume, at an average of 12,330.8 ppb for the past five years. The lowest concentrations were reported for well OW642, located south of the NAPL plume, at an average of 12.5 ppb. Groundwater samples are also collected from well OW808, installed into the ungrouted portion of the bedrock intake tunnel, located on Buckhorn Island. Data show average TVOC concentrations of 8.14 ppb, consistent with concentrations seen in the historical site sampling record ofnondirectly affected areas (background levels).

Groundwater Piezometric Monitoring

Water level data are collected on a quarterly basis from a network of monitor wells located in and adjacent to the S-Area Landfill to confirm hydraulic control of groundwater APL and NAPL. As per the RTT, monitoring and purge wells are used to evaluate the hydraulic conditions in the overburden and in different depths in the bedrock to confirm containment of contaminated groundwater. Over the last five years, measurements taken in overburden well pairs or river stage-well pairs located across the Barrier Wall showed flow gradients are consistently inward; some reverse gradients were observed (i.e., head difference of -9.47 measured in June of2013 measured between the river and OW551) due to anomalously high water for the season. Upward gradients are also determined by comparing groundwater elevations in overburden and shallow bedrock. Isopach contour maps derived from water-level differences are constructed on a quarterly basis; the most recent data show a net upward hydraulic gradients in most of the southern portion of S-Area (the northern portion of S-Area has a thick underlying clay layer that precludes downward groundwater flow) indicating that containment is largely achieved within the Barrier Wall.

Hydraulic gradient monitoring is also performed in the shallow, intermediate and deep bedrock zones relative to the respective bedrock NAPL plume boundaries. The objective is to maintain inward gradients across the NAPL plume boundaries and eliminate the potential for groundwater to migrate from the NAPL as APL. For the last five years, hydraulic head differences in well pairs located around the boundaries of the shallow and intermediate/deep NAPL plumes showed inward gradients for the most part. Some outward gradients were noted in certain intermediate/deep bedrock well pairs (i.e., an average head difference of -1.79 for well pair OW-638/0W-634 recorded in 2013) that are attributed to anomalously high water levels. However, APL contaminated groundwater was largely contained within the respective target-area aquifer zones.

In addition to hydraulic monitoring, a series of purge wells is installed to control NAPL/ APL migration in various zones in the bedrock. Hydraulic control is exerted across the purge well field by generating a sufficient drawdown through individually set target pumping rates. Seven APL bedrock purge wells are located along the southern edge of the shallow bedrock NAPL plume boundary and intercept groundwater from the southeast passing under the S-Area landfill through the shallow bedrock. A series of seven recovery wells is also installed along the southern edge of the shallow bedrock NAPL plume boundary. The wells remove available NAPL coming from the north from the landfill via dipping fractures. Five additional recovery wells are located

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along the eastern boundary of the shallow bedrock NAPL plume; these wells remove available NAPL coming from the west and prevent migration toward the new DWTP. Based on quarterly monitoring reports and annual evaluation reports for the 2009-2013 period, all wells are fully operational, operate within the target flow ranges, and maintain critical drawdown depths to affect capture of contaminated groundwater.

NAPL Tracer Program

As required by the RRT Stipulation, a NAPL Tracer Program (NTP) was established at the Hooker S-Area site and was implemented in two stages. The first stage began in October 1992 and was completed in 1999. The objective of the Stage I NTP was to collect data on volume and velocity of potential southward NAPL plume migration in shallow bedrock zone across a line of NAPL recovery wells installed just north of the Niagara River prior to installation and operations of the Purge Bedrock System (brought on-line starting in Nov 1995). The hydrophobic tracer 1,4-dibromobenzene was mixed with S-Area NAPL and injected into monitoring wells OW244 and O\Y245, located next to the Robert Moses Pkwy about 250 feet north of the river's edge. APL and NAPL samples were taken and evaluated from a line of shallow bedrock monitoring wells located along the Niagara River on a semi-annual basis for two years after injection and annually thereafter. Results from sample analysis showed that tracer was not detected in any APL or NAPL samples except for 7 ppb of 1 ,4-dibromobenzene reported in an APL sample from well OW238R in round 6 (May 1996). However, no additional tracer detection was confirmed in subsequent sampling rounds, therefore requiring a modification to the NTP.

Stage II of the NTP began in the second quarter of 2001 but was restarted in Aug 2003 with injection of a new tracer 1-bromohexane in wells OW244 and OW245. The objective of Stage II testing was to collect data to evaluate the effectiveness of the Bedrock RRT system in containing southward NAPL plume migration across a line ofNAPL recovery wells installed just north of the Niagara River. APL and NAPL samples were taken and evaluated from bedrock purge/recovery wells and bedrock monitoring wells located along the Niagara River semi­annually for two years after injection and annually thereafter. Results showed that tracer was not detected at or above the method detection limit in any APL or NAPL samples.

Based on the result that tracer was not detected in any APL/NAPL samples collected over the seven-year monitoring period, the report (NAPL Tracer Evaluation Summary Report S-Area Remedial Program, for GSHI by Connestoga-Rovers & Associates (CRA), August 2010) concluded that the bedrock RRT system is effective in containing southward NAPL plume migration across the line ofNAPL recovery wells immediately north of the Niagara River and, that no significant movement of the NAPL plume toward the pumping and nonpumping wells immediately north of the Niagara River has occurred. Further analysis of the data is currently underway to determine whether the objectives in the Stipulation Agreement regarding NAPL flow have been met.

Summary

The Landfill drainage systems are operating as designed based on the monitoring of site operations. The S-Area Overburden Remediation System currently contains the APL and NAPL. Collection ofNAPL has been maximized as demonstrated by the conversion of certain monitoring wells into NAPL recovery wells and the subsequent increase in NAPL collection

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quantity. Migration of contaminants to the City DWTP has been eliminated and the overburden remedial system has been shown to be working effectively by the continued monitoring and observance of the inward gradients within the barrier wall.

Based on the summarized monitoring data, the system has largely attained the remedial objectives set forth in the RRT Stipulation. The Shallow, Intermediate and Deep Bedrock systems have all achieved inward hydraulic gradients across most of the existing NAPL plume boundary within each of those zones. Routine adjustments are expected to be made to ensure the optimum performance of the system during the course of its operation. The Overburden Remedial System has collected approximately 255,000 gallons ofNAPL from the site since its startup in 1996.

The systems are operating as designed but minor alterations continue to be necessary to attain fully the inward and upward gradients of the site contamination called for in agreements. One of the requirements of the RRT that requires further evaluation is whether the extraction of the NAPL mass is stopping the migration of the NAPL plume under the Niagara River. The NTP, originally conducted beginning in October 1992, was modified and the test was subsequently conducted again in August 2003 since the first attempt did not provide useful information. Even though a substantial quantity of the NAPL mass is continually being removed from the site, it is difficult to observe directional changes of this NAPL body from the apex of this mass. The NAPL migration plan to verify that the NAPL body is no longer migrating under the Niagara River is currently being re-evaluated to determine if this observation is technically practicable. Observation of the chemistry in the water existing in the remaining Intake Tunnel void will continue.

Site Inspection

A site inspection was conducted on September 30, 2014. The following parties were in attendance:

Mark Bellis, On-Scene Coordinator, EPA Gary LaLiberty, CRA Jane Polovich, CRA

The purpose of the inspection was to assess the protectiveness of the remedy. No issues were observed at the time of the site inspection.

Interviews

During the five-year review process, no interviews were conducted. However, Michael Basile EPA CIC and Stanley Radon, NYSDEC Project Manager, who interact with the local public on a regular basis, report that they are not aware of members of the community having perceived problems with the implemented remedy.

Institutional Controls Verification

There are no institutional controls required by decision documents for this site. The site is fenced and guarded to assure no unauthorized access to the property.

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Technical Assessment

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

The remedy at the Hooker S-Area site appears to be functioning as intended by the decision documents. As described in the RRT of 1991, the remedy consists of the Overburden Remedial Systems, the Bedrock RRT System, and the Remedial Waste Management Program. The remedial objectives are to contain APL and NAPL within existing NAPL plume boundaries, to maximize the collection ofNAPL within the site barrier wall, to collect NAPL outside the Barrier Wall to the extent practicable, and to minimize potential migration of chemicals toward the DWTP and into the Niagara River.

The Overburden Remedial Systems manages contaminated groundwater in three distinct areas: the Site Containment System, which addresses the area beneath and adjacent to the S-Area site; the Overburden RRT System, which addresses areas outside the Site Containment System (south of S-Area); and the City DWTP Remedial Program, which addresses the property east of S-Area, the V -Area. The Site Containment System consists of a barrier wall that surrounds the S-Area Landfill, a drain collection system within the wall, a series site contaminant purge and recovery wells, and perimeter caps made of asphalt & composite material. The system functions to collect and contain APL/NAPL, and to minimize the migration of chemicals toward the city DWTP by maintaining inward gradients with respect to the barrier walls. Hydraulic data from the last five years of monitoring reports indicate that inward gradients are consistently maintained in the overburden relative to the barrier walls and in the V -area on the west side of S-area landfill. Monitoring wells between shallow bedrock and overburden indicate upward gradients. The collection system appears to be in good repair and target flow rates have been consistently achieved. Water-quality data show that, although there are site-related chemicals in monitoring wells in the V -area just outside the periphery of the site, these are similar to or less than the concentrations shown at startup and indicate that migration of APL away from the site does not appear to be occurring.

The Bedrock RRT System is comprised of a network of groundwater pumping wells, NAPL recovery wells, and monitoring wells for the shallow, intermediate, and deep bedrock zones. The purpose of the Bedrock RRT System is to contain and collect APL/NAPL hydraulically within existing area of bedrock NAPL plume, and to prevent NAPL migration in bedrock under Niagara River. The system is designed to remediate three distinct water bearing zones and achieve inward hydraulic gradients across existing plume boundary in each zone. Based on hydraulic data for the last five years, inward gradients have been consistently maintained in the shallow, intermediate, and deep bedrock zones relative to the area of the NAPL plumes. Based on the presence of NAPL observed in wells screened in the three bedrock zones, it appears that NAPL has not moved beyond the NAPL-plume boundaries that were established for the S-Area and that NAPL is contained within the S-Area. The water-quality results from intermediate bedrock wells OW693 and OW800, located along the Niagara River, show nondetectable concentrations or relatively low levels ofTVOCs; additionally, results from shallow bedrock wells OW240R and OW648, also located near the bank of the Niagara River, show lower levels ofTVOCs than other wells in the shallow bedrock group (average TVOCs of 129 ppb and 28 ppb, respectively).

A Remedial Waste Management Program is in place to process and dispose of contaminated groundwater extracted from the recovery wells. Groundwater influent is conveyed to a treatment facility equipped with carbon adsorption system to treat APL. Treated water is discharged to the

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Niagara River as per permit requirements. Leachate is conveyed to storage/handling facility and separated into APL and NAPL before treatment. NAPL is characterized and sent to an off-site RCRA facility for incineration. All systems are routinely maintained according to the Operation and Maintenance Plans and are functioning as designed.

The NAPL migration plan to verify that the NAPL body is no longer migrating under the Niagara River is currently being re-evaluated to determine if this observation is technically practicable.

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

Human Health- (a and b) The documents that were reviewed did not identify exposure assumptions or toxicity data that were used to evaluate the potential risks and hazards associated with the site. However, the previous five-year review (2009) indicated that the exposure parameters and toxicity data used at the time of the remedy selection were still valid and would not affect the protectiveness of the remedy. (c) The cleanup goals that were chosen for the groundwater were identified in the 1990 ROD. Although some of the chemicals do not have federal or state drinking water standards, the cleanup goals identified in the 1990 ROD remain valid because they fall within the acceptable risk range based (denoted by a range) or are below a hazard index of 1 (denoted by a single value) on EPA screening values, with the exception of mirex and 2,3,7,8-TCDD. The cleanup goals that were chosen remain valid. (d) The remedial action objectives (RAOs) that were identified in the 1990 ROD are still valid.

EPA has determined that there is no complete pathway for vapor intrusion at the site because there are no enclosed buildings located over the contaminant plume. Future five-year reviews should continue to evaluate if buildings are built over the plume.

EPA's dioxin reassessment has been developed and undergone review for many years, with the participation of scientific experts in EPA and other federal agencies, as well as scientific experts in the private sector and academia. The Agency followed current guidelines and incorporated the latest data and physiological/biochemical research into the reassessment. On February 17, 2012, EPA released the final human health noncancer dioxin reassessment, publishing an oral noncancer toxicity value, or reference dose (RID), of 7x10"10 mglkg-day for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in EPA's Integrated Risk Information System (IRIS). The dioxin cancer reassessment will follow thereafter. The dioxin RID was approved for immediate use at Superfund sites to ensure protection of human health. The revised RID for dioxin does not affect the remedy at Hooker S- Area since all contaminated soils are covered with an impermeable cap. Therefore, the remedy does not need to be reconsidered to determine if additional response is necessary.

Ecological - The documents that were reviewed did not identify exposure pathways or toxicity values that were used to evaluate ecological impacts from site-related contaminants. It is not clear if an ecological Risk assessment was conducted for the site. However, based on the implementation of the remedy, any potential pathways for ecological receptors have been eliminated through capping and groundwater control. Therefore based upon review of the past and current data, combined with the site visit, there are no completed exposure pathways for ecological receptors. The Niagara River is very swift near the site and taking samples would not be representative of site-related contamination.

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

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No human health or ecological risks have been identified, and no weather-related events have affected the protectiveness of the remedy. No other information has come to light that could call into question the protectiveness of the remedy.

Technical Assessment Summary

This site has ongoing operation, maintenance and monitoring activities as part of the selected remedy. As was anticipated by the decision documents, these activities are subject to routine modification and adjustment. This report did not identify any issues, recommendations or follow-up actions that need to be addressed to ensure the protection of public health and/or the environment. · ·

Issues, Recommendations and Follow-Up Actions

This site requires continual maintenance activities to ensure the effectiveness of the remedy. EPA has observed the PRP to be effective on observing, analyzing, and maintaining the remedial systems at the site on a regular and ongoing basis. EPA is presenting the following recommendations to the PRP for follow-up actions:

OU(s): 1 Issue Category: Monitoring

Issue: Determination that NAPL is no longer migrating into Canadian territory should be finalized.

Recommendation: Complete determination ofNAPL migration utilizing the submitted NAPL Tracer Study Report.

Affect Current Affect Future Party Oversight Milestone Date Protectiveness Protectiveness Responsible Party

No No PRP EPA/State 6/15/2016

Protectiveness Statement

Operable Unit: 1

Protectiveness Statement:

Protectin·ness Statement(s)

Protectiveness Determination: Protective

Addendum Due Date (if applicable): N/A

The remedy 1s protective of human health and the environment.

Sitewidc Protectiveness Statement I

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Protective N/A

Protectiveness Statement: The remedy is protective of human health and the environment.

Next Review

The next five-year review report for the Hooker S-Area Superfund site is required five years from the completion date of this review.

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Tables

Table 1 : Chronology of Site Events

Event Date

Leachate Storage and Handling Facility (LSHF) Construction Start June 1991

Aqueous Phase Liquid (APL) Treatment Plant Construction Start October 1992

LSHF Construction Completion iune 1993

APL Treatment Plant Construction Completion June 1994

Site Containment Purge Well Installation September 1994

Drain Collection System (DCS) Construction Start October 1994

Bedrock Requisite Remedial Technology (RRT) System Construction March 1995 Start

APL Treatment Plant Final Inspection April 1995

DCS Construction Completion June 1995

Bedrock RR T System Begins Operation July 1996

DCS Failure Determination January 1998

Drinking Water Treatment Plant (DWTP) Barrier Wall Completion June 1998

DWTP Capping Completion July 1998

Additional Bedrock RRT Forcemain Installation October 1998

DWTP Drain Collection System Completion January 1999

Bedrock RRT System Final Approval June 1999

First Five Year Review Report September 1999

RA Construction Final Inspection October 1999

DCS Final Construction Completion March2000

Landfill Cap Construction Start July 2000

Landfill Cap Final Inspection November 2001

Final Inspection of Site Construction Activities April2002

Second Five Year Review Report September 2004

Modification/Enhancement of Drain Collection System August 2006

Third Five Year Review Report September 2009

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

Author Date Title/Description

United States April1985 Stipulation and Judgment Approving Department of Justice SettlennentAgreennent

United States April 1991 Stipulation on Requisite Rennedial Technology Department of Justice Progrann

USEPA Septennber 1999 Five-Year Review of HookerS-Area Site

USEPA Septennber 2002 S-Area Site Landfill Cap Rennedial Action Report

USEPA Septennber 2003 S-Area Site Sub-Surface Rennediation Rennedial Action Report

USEPA Septennber 2003 S-Area Site Drinking Water Treatnnent Plant Rennedial Action Report

USEPA Septennber 2004 Second Five-Year Review Report

USEPA Septennber 2009 Third Five-Year Review Report

Conestoga-Rovers & First Quarter 2001 Quarterly Progress Reports Associates through present

Conestoga-Rovers & 2001 through 2014 Annual Evaluation Reports Associates

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Attachments

Fi ure 1: Site Map with june 2014 Shallow Groundwater Contours

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